CONTENTS

PART I

Jomnston, T. H., and Epmonpns, S. J.: Australian Acanthocephala, No. 8 ....

Awncei, F, M.: Notes on the Lepidoptera of the Northern Territory of Australia, with

Description of New Species

CoucuMan, L. E.: Notes on a Collection of Hesperiidae made by F. M. Angel in th

Northern Territory mes was bal ne ae ieee ra we an t

Jounston, T. H., and Mawson, P. M.: Additional Nematodes from Australian Fish ....

Kine, D.: Geology of the Pidinga Area .... ts san eae Ay ae ae rte

Wymonp, A. P., and Witson, R. B.: An Occurrence of Crocidolite near Robertstown,

South Australia... Ae ay, an ait ae Jnsh art ate his

Jounston, T. H., and Ancer, L. Maperine: The Life History of Plagiorchis Jaenschi,

a New Trematode from the Australian Water Rat

Tuomas, I. M.: Craspedacusta Sowerbyi in South Australia, with some Notes on its

Tabits

Jounston, T. H., and Ancet, L. Maprrine: The Morphology and Life Cycle of the

Trematode, Apatemon intermedius, from the Black Swan

Specutr, R. L.: A Reconnaissance Survey of the Soils and Vegetation of the Hundreds

of Tatiara, Wirreea and Stirling of County Buckingham, South Australia

Hossretp, Paut $.: Calcareous Tufa Deposits in Northern New Guinea ....

Spry, ALAN H.: The Archean Complex at Houghton, South Australia

Rrues, G. D.: Some New and Little-known Shore-bugs (Heteroptera-Saldidae) from the

Australian Region ....

Hiscock, I. D.: A Note on the Life History of the Australian Freshwater Mussel,

Hyridella australis Lam. ....

Rartican, J. H., and Wererner, C. F.: Granites of the Palmer Area and Associated

Granitized Sediments

Towarp, P. F.: The Basie Igneous Rocks of the Blinman Dome

Jessup, R. W.: The Soils, Geology and Vegetation of North-western South Australia ....

108

AUSTRALIAN ACANTHOCEPHALA NO. 8

BY T. HARVEY JOHNSTON AND S. J. EDMONDS

Summary

This paper deals with three species: (1) Mediorhynchus corcoracis n. sp. from Corcorax

melanorhamphus from Queensland, New South Wales and South Australia; it was also recognised

from Corvus bennetti from South Australia. The parasite is near M. tenuis Meyer but differs in size

and in having 12 spiral rows each containing 11-13 hooks. (2) Arhythmorhynchus frassoni (Molin)

is recorded from a sea curlew. Numenius cyanopus from Central Queensland coast. (3)

Longicollum pagrosomi Yamaguti was found in a bream, Mylio australis (Sparidae) from the lower

Brisbane River. It was known previously from Japanese fish.

AUSTRALIAN ACANTHOCEPHALA

No. 8

By T. Harvey Jounston and §. J. Epmoynps*

[Read 13 July 1950}

SUMMARY

This. paper deals with three species: (1) Mediorhynchus corcoracis n. sp.

from Corcorax melanorhamphus from Queensland, New South Wales and South

Australia; it was also recognised from Corvus bennetti from South Australia.

The parasite is near M, tenuis Meyer but differs in size and in having 12 spiral

rows each containing 11-13 hooks, (2) Arhythmorhynchus frassom (Molin)

is recorded from a sea curlew. Numenius cyanopus from Central Queensland coast,

(3) Longicollum pagrosomi Yamaguti was found in a bream, Mylto australis

(Sparidae) from the lower Brisbane River. It was known previously from

Japanese fish,

PARASITE - Hosr

Mediorhynchus corcoracis n. sp. Corcorax melanorhampus Vieillot

Corvus bennetti North

Arhythmorhynchus frassoni (Molin Numenius cynopus Vieillot

1858

ik pagrosom: Yamaguti Mylio australis Gunther

193

All the measurements given in this paper were made on_ specimens

cleared in methyl salicylate. Type material has been deposited im the South Aus-

tralian Museum.

Mediorhynchus corcoracis n. sp.

(Fig. 2-9)

Numerous specimens of this parasite, varying in size from the larval to the

adult form, have been found on a number of different occasions in the intestine of

Corcorax melunorhampus (type host). Most of the bird hosts were from New

South Wales; one was from the Upper Burnett River, Queensland (collected by

the late Dr. T. L. Bancroft) ; and we have found it in four Corcorax collected at

Elwomple, South Australia, by Mr. F. Jaensch. Some parasites obtained by

Professor J. B. Cleland from a crow, Corvus bennetti, near Oodnadatta, South

Australia, were identified by us as belotiging to the same species. About 80

specimens were available for examination.

ApuLt Form

The worms are long and slender and the body of many specimens is flexed

towards the anterior and posterior extremities. The largest males are 25 - 33 mm.

long, and the females 42-63 mm, The maximum width (a) anteriorly in the

males is 0°45 mm. and in the females 0°50 mm.; (b) in the mid-body region of

males, 0°-7- 1:4 mm. and of females 0-8 - 1-3 mm.; and (c) posteriorly 0'7 mm.

in both sexes. The armed portion of the proboscis in the male is 0°62 - 0°68 mm.

* University of Adelaide.

Trans. Roy Soc. S, Aust., 74, (1), March 1951

long, and in the female 0°64-0°75 mm, long. There is an unarmed neck 0-10 -

0-14 mm. long, The proboscis and neck of most specimens resemble in shape a

truncated cone. The armed portion of the proboscis consists of two parts; an

anterior portion which bears 12 spiral rows of 11-13 large hooks per row and a

posterior portion which bears 12 spiral rows of about 10-12 smaller and more

spiniform hooks, placed rather irregularly towards the neck, The width of the

anterior region of the proboscis is 0°19- 0°24 mm.; at the junction of the two

sets of hooks it is 0-28-0°38 mm.; and at the neck region it is 0°37 -0°-44 mm.

The size and shape of some of the hooks is shown in fig. 7,

Fig. 1, Arhythmorhynchus frassont, largest hook on ventral side of proboscis.

Fig. 2-5, Mediarhynchus corcoracis: 2, male; 3, female (to same scale as fig. 2);

4, larva emerging from cyst; 5, ripe eggs.

The proboscis sheath is 0°75- 1-04 mm. long and arises in the proboscis at

the junction of the two sets of hooks. The sheath is divided into two portions

by the proboscis retractor. There are two long and slender lemnisci, the maximum

dimensions of which are 4°0 mm. in length and 0°12 in width. They contain

numerous large nuclei, In none of the male specimens examined do they extend

as far back as the testes, as is the case with Mediorhynchus. tenuis Meyer 1931.

The body wall is thick and the lacunar system consists of a long horizontal canal

from which arise numerous circular vessels.

Two testes, 1:6-2°6 mm. long and 0‘4-0:7 mm. wide, are placed in tandem

in the posterior half of the worm, They are of about equal size. There are eight

elliptical to spherical cement glands placed very closely together. One specimen

seems to possess nine glands, The male genital opening is terminal,

The female genital structure in the largest female is about 1-9 mm, long.

Elliptical eggs mounted in balsam are 50-58, long and 28- 36m wide (fig. 5).

LARVAL FORM

A number of larvae just emerging from the cyst stage were also included in

the material from Corcoraxy melanorhamphus-—which is an insectivorous bird. In

most cases the neck and a partly everted proboscis had been freed from the cyst

case. The maximum length of these larvae was 2°20-2:71 mm, The cyst case

is elliptical, We estimate that its length would be 1‘6-1-9 mm., and its width

0:53 - 0°66 mm.

SysteMATIC POSITION

This species is very close to Mediorhynchus tenuis Meyer (1931, 68). For

some time we thought that we might be examining specimens of that species

larger than those described by Meyer, Our parasites, however, differ significantly

from: M_ tenuis im the number of prohoscis hooks, M. tenwis is armed with

12 spiral rows of 9 hooks per row, while our specimens have |2 spiral rows of

11-13 hooks per row. No fully everted proboscis of our specimens bears rows

of only 9 hooks. The anterior portion of the proboscis of M. coreoracis is a more

heavily armed structure than that shown in fig. 8 of Meyer's description of

M. tenuis, The male specimens of our species are much larger than those of

Meyer's species and in no specimen do the lemnisci extend as far as the testes.

ARHYTHMORHYNCHUs FRASSONI (Molin 1858)

(Fig. 1)

Three male specimens of this species were found in 1910 in the intestine of

a sea curlew, Numenius cyanopus, from Gladstone, Queensland. The parasites

are long and slender, the longest measuring 27 mm. The body just posterior

to the region which contains the lemnisci is swo'len most noticeably

and is 0-4-0'7 mm. wide, The swelling contains two testes placed almost

in tandem, The remainder of the body is cylindrical, except the posterior

portion which is broader and slightly flattened. The proboscis of none of the

specimens was completely everted. One, however, was about seven-eighths

everted and we consider that its armed portion when fully everted would be about

0-9 mm. long. It is swollen slightly near its middle where it is 0°30 mm. wide.

The proboscis bears numerous hooks, seventeen being visible in each row, and

we estitnate that when the proboscis is fully extended each row would show about

20 hocks. The differentiation in the sizé and shape af the hooks is most marked.

Those at the anterior end of the proboscis are smal'er and possess recurved root-

ing processes. A few hooks on the ventral side of the swollen region of the

proboscis are large and prominent and possess strong rooting processes, The

posterior hooks are longer and more slender and their axis makes an angle of

almost 90° with the axis of the proboscis. The anterior region of the body bears

spines. These extend much further along the ventral surface of the worm than

along the dorsal. The cement glands are very long and are pressed closely

together. Our specimens agree closely with the accounts given by Liihe (1911)

and Meyer (1933, 93). Saefftigen’s pouch is 1-4-1'7 mm. long.

This species has previously been reported from Numenius arquatus, N. tenu-

irostris and other birds in Europe.

Lowaercontum PaGRosomr Vamaguti 1935.

(Fig. 10)

Three male specimens of this parasite were identified in some material

obtained from the intestine of a breain, Mylio australis (Sparidae), caught in the

Brisbane River, Queensland, in 1918. The length of the cylindrical body varies

from 4°9-5-1 mm. All possess a very long neck, at the anterior extremity of

which is an armed proboscis. The combined length of the neck and proboscis is

4-7-5:6 mm. The anterior portion of the proboscis is swollen into a spherical

stricture which was fitmly embedded in the intestinal wall of the host, One

proboscis had already been freed from the tissue of the host and was hadly

damaged, One had completely collapsed and the hooks of the other were dis-

arranged when the remaining two specimens were dissected out by one of us,

The proboscis of the best preserved specimen is 0:85 mm. long and cousists of a

bulb about 0-40 mm. in diameter and a cylindrical portion about 0-45 mm. long

and 0-2 mm. wide. In size and shape the proboscis of our specimen resembles

very closely that of Spirorhynchus alemniscus Harada 1935, as shown in fig, 9

of Harada’s description. We have not been able to determine with certainty the

number and arrangement of proboscis hooks, There appear to be about 12 longi-

tudinal rows of about 11-13 hooks per row. The double-walled proboscis sheath

is long and arises just posterior to the last proboscis hook,

, ee,

40 ITS

ree

Fig. 6-9, Mediorhynchus corcoracis: 6, proboscis; 7, proboscis hooks; 8, posterior

region of adult male; 9, posterior region of young female.

Fig. 10, Longicollum pagrosomi, male.

The maximum diameter of the body is at the anterior region of the parasite

and is 0°53-1-1 mm. An elliptical mass is present near the posterior extremity

of the proboscis sheath. Two lemnisci, arising at the junction of the body and

the neck, are present in one specimen and are 0'8 mm. long. The body wall is

thick and the lacunar system reticular. Two oval testes, 0-49 - 0°63. mm. long and

0:23 -0-28 mm. wide, are placed obliquely in tandem. There are six cement

glands which appear to consist of 3 pairs, The most posterior pair are elliptical,

the others are much longer. Each gland communicates with the bursa by means

of its own slender duct, very much like the ducts in Tenuiproboscis misgurni

Yamaguti 1935.

Our specimens agree in most details with those of Spuorhynchus alemmiscus

Harada 1935. Yamaguti (1939), however, considered this species as synonymous

with Longicollum pagrosomi described by him in the same year (1935, 257),

from the upper part of the large intestine of Pagrosomus unicolor, the larval

stage occurring in many other Japanese fish, The proboscis of our specimens

with a small terminal bulb resembles that of Harada’s material very closely.

Yamaguti’s species possesses a short cylindrical proboscis. Well developed lemnisci

were observed in one of our specimens, Harada's material was obtained from

Scatophagus argus and Lutianus russelli from Formosa; Yamaguti (1935)

reported immature and mature forms from various marine fishes including

Sparus longispinis,

Harada created a family, Spirorhynchidae, to receive his genus (1935, 20).

Yamaguti placed his genus Longicollum along with Pomphorhynchus and Tenut-

proboscis in the Pomphorhynchidae (1939, 328), and stated that Harada’s

Spiracanthorhynchus (sic) was a synonym, Strand (Folia Zool. Hydrobiol.,

Riga, 1942, 388) pointed ont that Spirorhynchus Harada was preoccupied by

Da Cunha in 1915, and accordingly renamed it Spirerhynchodes. Hence we place

in the synonymy of Longicollum Yamaguti 1935 the following:—Spirorhynchus

Harada nee Da Cunha, Spiracanthorhynchus Yamaguti (error for Spirorhynchus)

and Spirorhynchodes Strand 1942; and Spirorhynchidae Harada as a synonym of

Pomphorhynchidae Yamaguti (1939, 328).

REFERENCES

Harana, I. 1935 Zur Acanthocephalenfauna von Japan. Mem, Fac. Sci. Agric.,

Taihoku Imp, Univ,, 14, (2), 1-23

Litaz, M. 1911 Acanthocephalen. In Brauer, Susswasserfauna Deutchlands,

Heft 16, 60 pp.

Mever, A. 1931 Neue Acanthocephalen aus dem Berliner Museum. Zool.

Jahrb. Syst., 62, 53-108

Mever, A. 1933 Acanthocephala, in Brtonn’s Klassen und Ordnungen des

Tierreichs, Bd. 4, Abt. 2, Buch 2, 582 pp.

Yamacutr, §. 1935 Studies in the Helminth Fauna of Japan. Part 8.

Acanthocephala I. Jap. Jour. Zool., 6, (2), 277-278.

Yamacutr, S. 1939 Studies in the Helminth Fauna of Japan, Part 29.

Acanthocephala II. Jap. Jour. Zool., 8, (3), 317-351

NOTES ON THE LEPIDOPTERA OF THE NORTHERN TERRITORY OF

AUSTRALIA, WITH DESCRIPTION OF A NEW SPECIES

BY F. M. ANGEL

Summary

This paper contains a list of sixty-three species of Rhopalocera collected in the Northern Territory

April-May 1948 by the author. There are several species not previously recorded from the Territory,

including two new to science. These new species have been described, and also a new Castniidae

(Sub-order Heterocera), under the following names:- Ogyris hewitsoni parsonsi — A variable race

from central Australia, bred from larvae. Suniana larrakia — One specimen from Darwin.

Description and notes by L. E. Couchman, F.R.E.S. Synemon wulwulam — A new clubbed-antennae

moth from Pine Creek. Types are figured on a photographic plate.

NOTES ON THE LEPIDOPTERA OF THE NORTHERN TERRITORY OF

AUSTRALIA, WITH DESCRIPTION OF NEW SPECIES

By F. M. Ancen

[Read 13 July 1950]

SUMMARY

This paper contains a list of sixty-three species of Rhopalocera collected in the

Northern Territory April-May 1948 by the author. There are several species not

previously recorded from the Territory, including two new to science. These new

species have been described, and also a new Castniidae (Sub-order Heterocera),

under the follawing names :—

Ogyris hewitsoni parsonsi—A yariable race from Central Australia, bred

from larvae.

Suniana larrakia—One specimen from Darwin, Description and notes by

L, E. Couchman, F.R.E.S.

Synemon wultvnlam—A new clubbed-antennae moth from Pine Creek.

Types are figured on a photographic plate.

DISCUSSION

During the months of April and May, 1948, Mr. F. E. Parsons and the

writer spent five weeks on a collecting trip between Adelaide, South Australia,

and Darwin, Northern Territory, during which a systematic survey was made

of the Rhopalocera of the Northern Territory, along and within a short distance

of the Stuart Highway.

Although in the aggregate a lot of entomological material has been collected

in the Darwin area, very little appears te have been published abont it; so the

object of this paper is to record the species collected in the various localities

visited during the above mentioned trip, in the hope that it may add a little to

our knowledge of the distribution of the Australian butterflies in the less fre-

quented parts of the North.

The time of the year, April 15- May 10 1948, was after the wet season, and

during the whole trip no rain was experienced. However, the roads to Daly River

and Alligator River were reported to be impassable, which made a contemplated

visit to those parts impracticable. Consequently the collecting about Darwin was

confined to short daily trips,

As might be expected very little insect life was in evidence in the dry country

between Alice Springs and Elliott, and it was not until the better watered parts

of the Northern Territory were reached that the tropical species began to appear-

In all, sixty-three species of Rhopalocera were recorded during the trip,

including two new species, as well as a number of Heterocera,

In the preparation of this paper, the author acknowledges the very great help

he has received from the following gentlemen:—Mr. N. B, Tindale, of the South

Australian Museum, for his kindness in preparing the photographic plate and

assistance in the identification of species; Mr. J.. E. Couchman, F.R.E.S., of

Hobart, who so willingly undertook the description of the new species of Suntanc

and the examination of the specimens of the difficult Subfamily Hesperiinae,

involving much bibliographical research. His interesting notes and description

are included as an addendum to this paper, Special thanks are also due and

hereby acknowledged to Mr. F. E. Parsons, who collaborated in collecting

material and generously provided the motor car for the trip.

Trans, Rey Soc, S, Aust,, 74, (1), March 1951

Order LEPIDOPTERA

Suborder RHOPALOCERA

DANAIDAE,

Danaus chrysippus petilia (Stoll) 1790.

This widely distributed species was abundant at Darwin, and was observed

at Elliott, Katherine, Adelaide River and Roper River.

Danaus affinis affinis (Fabricius) 1775,

Common at Darwin and Manton Riyer, also occurs at Katherine, Adelaide

and Roper Rivers, and Pine Creek.

Danaus hamata hamata Macleay 1826.

Mostly seen in a small rain-forest patch near Darwin, but not abundant.

Several observed at Adelaide River and Katherine. Specimens taken in

April were mostly worn, but some captured in May appeared to be freshly

emerged,

Euploea core corinna (Macleay) 1826.

This is the common Euploce of the North, and was toted at Katherine,

Adelaide River, Pine Creek, Manton River, Berry Springs and Darwin.

The dense shade in forest areas seems to be particularly attractive to this

butterfly. Larvae from a stall creeper at Elizabeth River, pupated and

emerged within a fortnight.

Euploea pelor Doubleday 1847.

Rather scarce and only found in the densely shaded rain-forest at Knight

Beach, about four miles from Darwin.

Euploea darchia darchia (Macleay) 1826.

Not common. Mostly observed above the cliffs near the beach at Darwin.

Has a leisurely floating flight and is easily catight.

SATYEIDAE,

Melanitis leda bankia (Fabricius) 1775.

First observed at Adelaide River flying at dusk and settling on a cask

at the rear of the hotel. Very common at Darwin, where several larvae

and many pupae were found in coarse grass. Both the ocellated and plain

forms of this vatiable species were obtained, some of the latter being

almost black on the underside. This species was seen at Manton Weir,

and at the lily ponds near Pine Creek.

Mycalesis perseus perseus (Fabricius) 1775.

Specimens taken at Elizabeth River and at several localities near Darwin.

Keeps to the grass and undergrowth in damp places, usually near running

water.

Myculesis sirius sirius (Fabricius) 1775.

Its habits resemble those of M. p. perseus; both species are sometimes

found flying in association. Specimens taken are from Darwin, Berry

Springs and Adelaide River,

Ypthima arctous (Fabricius) 1775.

Common at Darwin, Berry Springs, Manton River and Pine Creek. It

frequents the grass and has a weak flight,

Hypocysta adiante antirius Butler 1868.

This dainty little Satyrid is widely distributed and common. Specimens

taken are from Adelaide River, Pine Creek, Manton River, Berry Springs

and Darwin, Although its flight is weak and it seldom flies far, its habit

of flying through the long coarse grass demands patience to secure good

specimens,

NYMPHALIDAE.

Hypolimnas bolina nerina (Fabricius) 1775.

Unexpectedly, this well-known butterfly was rather scarce. Most speci-

mens seen during April were much worn, but some fresh examples were

secured during the month of May, suggesting the time of our visit was

between broods. Captures were made at Darwin, Adelaide River and

Katherine. Two pupae were obtained at Katherine on 12 May.

Hypolimnas misippus (Linnaeus) 1764,

More plentiful than the previous species. At Adelaide River both sexes

were moderately plentiful in a cucumber patch in a soldier’s garden, The

owner stated that the butterflies were attacking the cucumbers, but on

being questioned, admitted that he had not seen any caterpillars on the vines.

A careful search failed to find larvae or pupae. On entering the outdoor

bedroom at the hotel at Adelaide River, two pupae were found suspended

head downwards, under the window, from which a pair of H. misippus

emerged. The pupa of this species resembles that of H. bolinw in shape and

has similar sharp dorsal spines, but is smaller and of a uniform brown

colour, This species was not uncommon at Darwin. On the wing the

female is hard to distinguish from Danaus c. petilia, in spite of a different

flight.

Cethosia penthestlea paksha Fruhstorfer 1905.

This is another species that closely resembles Danaus c. petilia when flying.

Two specimens were taken near the cliffs at Darwin, and on only one

other occasion was it positively identified when it flew into a dense forest,

near Knight Beach.

Precis vilida calybe (Godart) 1819,

The commonest butterfly seen in the dry interior. Along the railway line

from Quorn to Alice Springs it was identified at frequent intervals. On

the Stuart Highway from Alice Springs it was seen as far as Elliott, where

examples were collected. On the return journey it was scarce, so that

May would seem to be the end of its season in the interior.

Precis ortthya albicincta (Butler) 1875.

First observed near Dunmarra, occasionally at Katherine, and commonly

at Pine Creek, Adelaide River and Darwin, It was fond of sunning itself

on the hitumen roads, but when approached was very alert and actively

took flight. The habitat of this and the previous species did not appear

to overlap,

Precis hedonia selima (Fabricius) 1775,

Not common, Observed near Darwin, Berry Springs, Manton River,

Elizabeth River, Pine Creek and Lily Ponds, ustially near running water.

Faas a restless flight and keeps to the undergrowth close to streams.

Acraea andromacha (Fabricius) 1775.

Very common and, with its slow flight, easily captured. Recorded from

Laramah, Katherine, Pine Creek, Adelaide River, Manton River, Berry

Springs and Darwin.

LyYCAENIDAE,

Nacaduba ancyra estrella Waterhouse and Lyell 1914. Specimens taken at

Adelaide River and Darwin. Very few were seen,

Nacaduba dubiosa dubiosa (Semper) 1878.

This species was also seldom observed. Examples recorded are from

Adelaide River and Darwin.

Nacaduba biocellata biocellata (Felder) 1865,

Outside the Gap at Alice Springs this double spotted blue was flying in

small numbers and settling on the leaves of a species of Acacia, It was

not seen further north.

Everes argiades (Pallas) 1771.

Very few seen, Specimens were collected at Adelaide River and Darwin.

Euchrysops cnejus cnidus Waterhouse and Lyell 1914,

Generally observed in all localities visited from Katherine to Darwin-

Specimens were collected at Katherine, Adelaide River and Darwin.

Jamides phaseli (Mathew) 1889. ;

Only seen at Darwin where it was very scarce, and only two specimens

were collected,

Catochrysops platissa (Herrich-Schaeffer) 1869,

First observed at Laramah settling on the wet ground at a mtiddy pool

at the railway station, Specimens taken were from Katherine and Darwin.

Anihene emolus affinis (Waterhouse and Turner) 1904.

Rather common at certain spots near Darwin, A fair size colony of larvae

and pupae was found on a small sapling near Knight Beach. They were

attended by greet ants. This species was also recorded from Katherine.

Zizeeria labradus labradus (Godart) 1819.

This notoriously commion Blue was in evidence at all localities inspected.

Examples were obtained at Alice Springs, Wauchope, Elliott, Adelaide

River, and Darwin; those from the drier parts, such as Wauchope, being

below the average size,

Zigeeria alsulus alsulus (Herrich-Schaeffer) 1869.

Occurs in most localities north from Katherine. Specimens were collected

at Katherine, Dunmarra, Daly Waters, and Darwin.

Ziseeria trochilus putli (Kollar) 1844, $

This dainty little Blue frequents the long grass at Darwin but was not

often seen, and only two examples were obtained.

Neolucia serpentata (Herrich-Schaeffer) 1869.

Observed flying in a garden at Alice Springs where specimens were

obtained. It is a darker race than the species from South Australia, Was

not seen north of Alice Springs.

Theclinesthes miskini (Lucas) 1889.

Specimens collected at Katherine and Darwin have been identified as a

small race of this species,

Ogyris hewitsoni parsonsi subsp. nov,

Plate I; fig. 7, 8, 9, 10

Male—Above with forewing bright spectrum blue, changing to blue-violet

when obliquely viewed; apex and termen narrowly edged with black; cilia smoky

grey, almost black at the terminations of the veins, Ilindwing bright spectrum

une ; costa narrowly black; termen very narrowly black; cilia light grey with black

at the veins.

Beneath with forewing brownish-grey; area of cell black with five dull

white transverse bars which usually are tinged with blue; ‘a discal dark brown

band broken into five irregularly offset sub-rectangular segments, the second being

shifted towards apex, and the third towards the base. Hindwing dark grey,

lighter towards apex and termen; an irregiilar wavy pattern of darker grey scales,

each pattern margined with black lines.

Female—Above with forewing bright spectrum blue changing to blue-violet

when obliquely viewed; white suffusions in cell and in discal area; costa, apex

and termen narrowly black; a narrow black bar at end of cell; veins beyond cell

faintly black; margin of costa near apex, apex, and termen with small grey patches;

cilia grey with black fringe. Hindwing bright spectrum blue; custa and apex

black, edged with grey; termen and tornus narrowly black; cilia grey with black

fringes.

Beneath with small cell bar at base of forewing orange-brown; a second

cell bar narrowly black’>a third larger and burnt orange in colour; each bar edged

with metallic blue; end of cell with a silver spot, tinged faintly with bluc, and

surrounded by a broad black area; inner discal area white; discal band black,

area beyond discal band to apex with termen light grey, shading darker. Hind-

wing grey, lighter near costa and apex; in centre of wing a sub-rectangular or

zig-zag dark patch; other markings grey, edged with black.

Holotype male, labelled Aileron, Northern Territory of Australia, 5 Septen-

ber 1948, and allotype female, labelled Aileron, Northern Territory, 2 September

1948, collected by F. M. Angel. Both specimens in the collection of the writer;

length of forewings respectively 19 mm. and 21 mm,

In addition to the type pair, thirty males and twenty-seven females were bred

from jarvae taken near Aileron, Northern Territory, on desert oaks (Casuarina)

on which mistletoe was attached. Five males were captured on the wing on

15 May 1948. The bred specimens emerged at various dates between 5 August

and 14 September 1948. All these specimens have been examined.

The type pair selected from the above series are examples of the dominant

form, The series as a whole shows considerable variations in markings, par-

ticularly on their undersides. In several examples of both sexes the discal band

is reduced to two small spots, in areas 2 and 3, and there are other specimens with.

intermediate stgges between this .and the dominant form. The general colou;

scheme on the underside also varies; in two females the conspicuous coloured bar

in the cell is dark brown, while one of these ig entirely without the discal band;

possibly the last named is an aberration,

Another form of variation is in the shade .of blue of the upper surface of

both sexes. Two different colour types are present; however, the difference

between the spectrum blue form and a slightly paler one are so slight that no

colour names can be found to differentiate them. Length of forewings, males

16-20 mm., females 18-22 mm.

Ogyris hewitsoni parsonsi may be distinguished from typical O. h, hewitsont

by the different shade of blue, and by possessing very narrow black margins to the

upper side of the wings, The white suffusion present in the female is chatacteris-

tic, and the narrow bar at the end'‘of the cell (vestigial in some exampies) makes

this sex also readily recognisable from typical O. h, hewitsont,

All the specimens taken on the trip have been coimpared with the long series

of species representing O. amaryllis and O, hewitsoni in the South Australian

Museum at Adelaide, as well as those in the collections of F, E. Parsons and the

ety In the South Australian Museum there are two specimens labelled as

follaws >—

1 male, Konamata, west of Mount Kintore, North-West of South Aus-

tralia, July 1933, collected by N. B. Tindale,

L “e Central Mount Stuart, Central Australia, collected by F, Wood

ones,

These are identical with the above specimens and ate hereby designated as

paratypes. They indicate that the range of this race extends over a considerable

area of Central Australia.

The food plant is a greyish spectes of mistletoe growing on Desert Oak

(Casuarina Decaisneana), In ihe daytime, the larvae shelter tinder loose bark

or other suitable covet and are attended by a small species of black ant. In some

instances where there was no other suitable shelter, larvae were found in ant

tunnels in loose earth. In captivity the larvae were without the ants and their

natural food plant, but fed on apple, and a fair proportion were successfully

reared.

It may be of interest to record that a specimen of Ogyris hewitsont, probably

this race, was observed from the train about twenty miles south of Alice Springs

on 18 April, one on the Stuart Highway about fifty miles north of Alice Springs

on 20 April, and on 15 May a small number was seen on the Wing near Atleron.

The interval of approximately three months or more between these dates,

and the emergence of the bred specimens, suggests that this tace has at least two

broods during the year.

This sub-species is named in honour of Frank E, Parsons, who shared with

the writer in the discovery and rearing of this new race,

The paratypes figured on pl. I are examples of the variant markings

of the underwings, more particularly in the discal area of both sexes. As men-

tioned in the description, the dominant form has a continuous though irregular

discal band, but this feature is not constant in some specimens and varies in

intermediate stages from a well-defined band ta two small spots. The upper

sides of the specimens figtired agree very well with the holotype and allotype,

but allowance should be made for the fact the photographic process does not shaw

the white suffusion on the female, which is a distinctive feature of that sex of

’ the subspecies,

Amblypodia centaurus asopus (Waterhouse & Lyell) 1914.

Observed in several localities along the coastal cliffs at Darwin, and also

at Patap. It has a strong flight and usually settles high up in trees, but

sometimes in low shrubs; in ail cases green ants (Oecophylla smaragdina }

were present near the resting place.

Amblypodia amytis amydon Waterhouse 1942,

Its habits resemble those of the former species, and specimens wert

obtained in the sare localities, In spite of its. brilliant colouring on the

upper surface of the wings, it is not very conspicuous in flight or at rest.

It appeared to be rather more niimerous than 4, c. asopus. A pupa

obtained at Elizabeth River, which failed to emerge, was no doubt an

Amblypodia, although no butterfly of either species was seen there,

Hypolycaena phorbas ingura Tindale 1923,

This butterfly is also associated with the green tree-ant, and is often seen

on the same shrubs that 4mblypodia frequents. The species was rather

plentiful in the Darwin area but only occasionally seen inland.

PIERIDAE

Elodina perdita walkeri Butler 1898.

Taken at Darwin flying along the top of the cliffs, also at Berry Springs

and Adelaide River. Nowhere was it plentiful or flying in numbers,

Cepora perimale scyllara (Macleay) 1826.

Noticed at Laramah settling on a drying muddy pool on the road. At

Adelaide River, Pine Creek, Manton River, Berry Springs atid Darwiti it

was fairly plentiful. Specimens captured showed that they were all of

the light phase on the tnderside, either white or pale yellow.

Anaphaets java teutonia (Fabricius) 1775,

Odd specimens were observed from the train when nearing Alice Springs.

Near the Gap this species was flying in hundreds about a large Cassia

bush which was stripped almost bare, and on which there were many pupae,

and a few larvae struggling for existence. Within fifty yards there were

several healthy Cassia shrubs which the butterfly apparently had ignored.

This species was also. found flying in small numbers at Elliott,

Appias paulina ega (Boisduval) 1836.

This species was mostly confined to a small rain-forest near Knight Beach,

about four miles from Darwin, where a small number were present,

Nearer Darwin it was occasionally seen.

Eurema hecabe phoebus (Butler) 1886.

Specimens were taken at Daly Waters, Katherine, Pine Creek, Adelaide

River, Manton River, Elizabeth River, Berry Springs and Darwin. It is

the commonest of the grass yellows in the North, and varies considerably

in size.

Eurema drona. australis (Wallace) 1867,

Recorded from Pine Creek.

Eurema lazta herla (Macleay) 1826,

Several specimens collected at Pine Creek.

Eurema smilaxy (Donovan) 1805,

Often seen along the Stuart Highway. Specimens were taken at Dun-

marra, Pine Creek, Adelaide River and Darwin.

Eurema sana (Butler) 1877,

This species apparently was rare, One specimen was taken at Pine Creek,

and another at Adelaide River.

Catopsilia pomona pomona (Fabricius) 1775).

First observed at Elliott, and later at Laramah, At Darwin it was very

common along the cliffs, and larvae were found in great numbers; in one

instance the foodplant had been completely defoliated. Specimens, both

captured and bred, varied considerably in size. Length of forewing varied

from 22 min. to 40 mm.

Catopsilia scylla etesia (Hewitson) 1867.

Although often observed flying with the former species it appeated to be

rather scarce. Specimens were taken at the Darwin cliffs, but more often

near a rain-forest at Knight Beach.

PAaPiILioNIDAE,

Papilio fuscus canopus Westwood 1842, -

Only a few examples of this swallow-tail were seen, and these in a dense

rain-forest near Knight Beach. Specimens captured were all more or less

ragged and worn, which seemed to indicate that it was the end of the

season for this species,

Papilio demoleus sthenelus Macleay 1826.

One specimen was seen at Wauchope flying over an Oleander shrub, At

Katherine a small number was seen flying near its foodplant on which one

pupa and several half-grown larvae were found. The latter were left for

observation on the return journey, but unfortunately a bush fire had

destroyed the food plants before the subsequent visit. The butterfly is

a strong flyer and very wary. Specimens were collected at Katherine, and

one example at Pine Creek. The last mentioned locality is the farthest

north the species was noted,

Papilio eurypylus nyctirmus Waterhouse and Lyell 1914. - ;

One freshly emerged example was seen hovering over a flowering tree at

the edge of the cliffs at Darwin.

Cressida cressida cassandra (Waterhouse and Lyell) 1914.

This species was found rather plentifully at Adelaide River, Berry Springs

and other localities near Darwin.

HESPERIIDAE

Neohesperilla croceus (Miskin) 1889.

Two examples taken at Adelaide River on 24th April were the only

specimens seen.

Taractrocera dolon diomedes Waterhouse 1933.

Superficially the species of the Subfamily Hesperiinae are so much alike

when seen in the field, that it is almost impossible to distinguish them with

certainty, Particularly is this so with the genera Taractrocera and Ocy-

badistes, and as the number of individuals of thesc two were never plentiful,

the species represented in the specimens captured were more than expected.

The abovementioned species was represented by a single example taken

at Adelaide River.

Taractrocera ina ina Waterhouse 1932,

Several specimens were taken at Datwin on various dates.

Ocybadistes flavovittata vesta Waterhouse 1932,

This species was found in several localities at Darwin, and also at Berry

Springs, but at no time were many observed flying together.

Ocybadistes walkerit olivia Waterhouse 1932.

Mostly taken at Berry Springs, where in a small patch near the river they

were in fair numbers. Specimens were also collected occasionally at

Darwin.

Ocybadistes hypomeloma vaga Waterhouse 1932.

This larger species was rarely seen. Two specimens were obtained at

Adelaide River on 24th April, and one at Darwin on 30th April.

Suniana larrakia n.sp, (vide description by Mr. L, E. Couchman in

addendum),

A specimen taken at Darwin on 28th April 1948 was the only one observed.

Telicota colon argeus (Ploetz) 1883,

Its bright colouring makes this species conspictious in the field, and it was

fairly common at Darwin and Berry Springs, Specimens were also taken

at Adelaide River and Katherine.

Telicota augias argilus Waterhouse 1937.

Resembles the previous species in colour and habits, but was not so plenti-

ful. Examples were collected at Berry Springs and Darwin.

Cephrenes trichopepla (Lower) 1908.

Frequently seen in the Darwin area, where its strong flight and showy

appearance when it settles attracts attention. It was also noted at Adelaide

River.

Borbo impar lavinia (Waterhouse) 1932.

This was scarce. One specimen was taken at Adelaide River on 24 April,

and also at Darwin on 28 April and 4 May 1948.

Borbo cinnara (Wallace) 1866.

Specimens were obtained at Adelaide River, Darwin and Berry Springs,

where it was more plentiful than the preceding species.

Pelopidas agna dingo Evans 1949,

Recorded from Darwin and Berry Springs during ihe first week of May,

but was only seen occasionally.

Order LEPIDOPTERA

Suborder HETEROCERA

Family CASTNIIDAE

Plate I; fg. 1, 2, 3, 4

Synemon wulwulam n. sp.

Male—Expanse of wings 39 mm, :

Above, with forewing light brown, darker at termen; costa pale cream; a

transverse cream area extending from outer part of cell towards tornus to area 2,

where it joins with a narrow curved discal band from near the apex; within this

lighter area at end of cell an irregular spot dark brown; veins in discal area cream;

termen rounded; cilia brown, Hindwing dark’ brown, almost black, with outer

ends of areas 2 and 3 somewhat paler; three or more sub-terminal spots in areas

4, 5, and 6 dull ochreous yellow; termen and cilia with predominantly dark brown

scales, Beneath with basal part of forewing from middle of cell to tornus dark

brown; outer part of cell to tornus and apex golden yellow; an elongated spot at

end of cell dark brown; apex of wing narrowly black; ends of veins from below

apex to tornus dark brown obscured with yellow scales; cilia opalescent white

with a narrow brown line, Hindwing dark brown almost black; a series of

paired spots in areas 2, 3, 5, and 6, and one spot in area 4 golden yellow; cilia

with brown and white scales.

Female—Expanse of wings 41 mm.

Above, forewing resembles in markings that of the male, but the colour in

the basal half of wing is a somewhat darker brown which accentuates the pattern,

and the elongated spot at end of cell is more prominent; cilia with predominantly

greyish-white scales. Hindwing very dark brown; areas 2, 3, and 4 have each a

single rather brighter ochreous yellow spot near termen, area 5 has two conjoined

bright yellow spots, and area 6 a short yellow band formed from two spots; cilia

brown with some white scales. Underneath of both wings similar to male,

In both sexes the head, tharax and abdomen are dull brown above and

greyish-white beneath. The clubbed antennae are brown above, but underneath

the terminal portion of the antennae is greyish-white.

Holotype male, labelled Pine Creek, Northern Territory of Australia,

23 April 1948; and allotype female, labelled Pine Creek, Northern Territory,

11 May 1948, collected by F. M. Angel. Both specimens in the collection of the

writer ; paratypes are lodged in the South Australian Museum,

The type pair have been setected from a series of twenty-five specimens

captured at Pine Creek; it was taken also at Adelaide River, and near Dunmarra.

At the last mentioned locality, where the species was first observed, it was flying

amongst short undergrowth in a damp spot. A few specimens taken there are

larger than the types. At Pine Creek it frequented a dry comparatively bare patch

on which the only vegetation was a short stunted species of sedge, which was

probably its food plant. The moth was flying in fair numbers on both visits on

23 April and 11 May 1948.

. ‘The most striking characteristie of the species is the large golden-yellow

pateh on the underside oi the forewings; the alternate flashing and disappearance

of this makes the insect very conspicuous when it is in fight.

Trans, Roy. Soc. S, Aust., 1950 Vol. 74, Plate I

Synenon wulwulam n.sp. Holotype male, upperside. Pine Creek, N.T., 23 April 1948.

Underside of same specimen.

Allotype female, upperside. Pine Creek, N.T., 11 May 1948.

Underside of same female specimen.

Suniana larrakia 1. sp. Holotype female, upperside. Darwin, N.T., 28 April 1948.

Underside of same specimen.

Ogyris hewitsont parsonsi n. sp. Paratype male. Aileron, N.T., 5 September 1948,

Underside of same male specimen.

Paratype female, upperside. Aileron, N.T., 14 September 1948.

Underside of same female specimen.

All figures are approximately natural size.

NOTES ON A COLLECTION OF HESPERITDAE MADE BY F. M. ANGEL

IN THE NORTHERN TERRITORY

BY L. E. COUCHMAN

Summary

Among a number of specimens of the family Hesperiidae recently collected by F. M. Angel in the

Northern Territory there are several of considerable interest, notably a new Suniana represented by

a single female. In listing these I have adopted the order of genera as given by Evans (1949, Catal.

Hesperiidae, Europe, Asia and Australia), an outstanding work that will undoubtedly remain the

basis for future work for many years to come.

NOTES ON A COLLECTION OF HESPERIIDAE MADE BY

F, M. ANGEL IN THE NORTHERN TERRITORY

L, E, Coucuman, F_R.E.S,

Among a number of specimens of the family Ilesperiidae recetitly collected

by F. M. Angel in the Northern Territory there are several of considerable

interest, notably a new Sunidna represented by a single female. In listing these

I have adopted the order of genera as piven by Evans (1949, Catal, Hesperiidae,

Europe, Asia and Australia), an outstanding work that will undoubtedly remain

the basis for future work for many years to come,

Subfamily TRAPEZITINAE

Neohesperilla croceus (Miskin) 1889. Darwin, N.T.

Although Evans (1949, Intro. p. XII) claims to have retained the original

spelling of genera and species, in using “crocea,” as elsewhere with “Passa

tasmanica,’ he has followed Waterhouse and Lyell (1914) in amending

Miskin’s names.

Subfamily HESPERIINAE

Taractrocera dolon diomedes Waterhouse 1933, Adelaide River,, N.T., 24-448.

1 male,

The specimen is yery worn, but I have no doubt it is referable to this species.

Taractrocera t. ina Waterhouse 1932, Darwin, N.T., 24-4-48, 30-448. Male

and female. ;

Ocybadistes flavovittata vesta Waterhouse 1932. Darwin, N.T., 27-4-48, 8-5-48.

Males.

Ocybadistes walkeri olivia Waterhouse 1933, Darwin, N.T., 445-48, 5-5-48,

Males.

Tncluded here is one unustially small specimen with restricted markings which

tnay prove distinct, but in the absence of more material I place it as a small

specimen of this subspecies of O. walkeri.

Ocybadistes hypomeloma vaga Waterhouse 1932. Adelaide River, N.T., 24-448;

Darwin, N.T., 30-4-48. Males.

These specimens have but a faint indication of the distinctive white dorsum

on the underside of the hindwings which is characteristic of the type form from

Sydney, New South Wales, and do not exactly conform to Waterhouse's descrip-

tion of ssp. vaga, but since Waterhouse himself records O.h. vaga from Brock’s

Creek, N.T. (1933, Proc. Linn. Soc. N.S.W., 58 (5/6): 461), I place these

specimens here. This is the first record of the species from Darwin.

Suniana larrakia nov. sp.

Plate I; fig. 5, 6

(the native name of the original tribe inhabiting the Darwin district),

Holotype female. Ground colour of forewings and hindwings above mummy

brown (Ridgway, Colour Standards and Colour Nomenclature: 15); markings

aboye cadmium yellow (Ridgway 3).

Forewing, cell and costa to vein 9 cadmium yellow, the narrow costal portion

of this patch clearly divided by veins 10, 11 and 12, Three small subapical spots,

a narrow streak along dorsum and a few scattered scales at base, cadmium yellow,

A straight discal band of five spots, from vein 1 at 5 mm. from base towards

apex at vein 6, each 1 mm. square, clearly separated by the vems, cadmium yellow.

Hindwing, a few scattered basal scales, a minute spot in area 7, a straight discal

band of four rectangular spots, 1-$ mm. by 1 mm., from vein } at halt towards

apex at vein 6, clearly divided by the veins, and a few scattered scales along

dorsum, cadmium yellow. Cilia of fore and hindwings brown narrowly tipped

cadmium yellow, except at termen of hindwing where the whole width of the

cilia is cadmium yellow.

Beneath, forewing mummy brown; cell spot, costal area from base to beyond

cell, discal bands and subapical spots as above, with an apical suffusion, cadmium

yellow. Cilia brown, tipped cadmium yellow. Hindwing suffused cadmium

yellow except for a small spot of ground colour at tornus; the discal band of

cadmium yellow spots outlined by the dark veins and by dark crescentic lines,

Cilia cadniium yellow. Forewing length 10°5 mm,

Allotype male. Colouration and markings of male as in female, differing

only in the slightly deeper tone of the cadmium yellow markings of fore end_

hindwings above, while the distinct separation of these markings by the veins #4

not so clearly defined as in the holotype female, Forewing length 10-5 mm. ~

Holotype Female labelled Darwin, N.T., 28-4-48, F. M. Angel, in the collec-

tion of F. M, Angel, Allotype male labelled N.W. Australia. K.L. 12038 in the

G. A, Waterhouse collection at the Australian Museum, Sydney, Three paratypes,

believed to be females, but determination not certain owing to the damaged state

of the terminal segments, labelled Groote Eyland, N. Territory, N, B. Tindale

and dated Dec, 1921, February 1922 and March 1922, respectively; in the collec-

tion of the South Austtalian Musetim, Adelaide,

This is a neat little species, easily distinguished from the other members of

the genus (S. lascizta Rosenstock and S, sunias Felder) found in Australia. From

S. lascivia it can be distinguished by the uniform width of the discal band of

forewing above, and the pale yellow suffusion of the hindwing beneath; from

S. sunias in both sexes by the uniformly narrow markitgs of the forewing above,

the costal, apical and discal markings being clearly separate, and themselves broken

by the darker veins, while the male of S. larrakta is without the broad sex brand

of S. sunias Felder as defined by Waterhouse and Lyell (Butt. of Australia: 204).

Telicota colon argeus (Ploetz) 1883. Darwin, N.T., 30-4-48; 8-5-48. Males

Adelaide River, N.T., 24-4-48, Male.

Corbet (1942, Proc. R. Ent, Soc. Lond, (B) 11:92) has shown that the

type males of T. augias Linn. proves to be conspecific with T. kreffti

Macleay; the oldest name for any form of the collective species hitherto

known as T, augins auctt, (nec Linn.) is T. colow Fabricius 1775.

Telicota augias argilus Waterhouse 1937. Darwin, N.T., 27-4-48, 7-5-48. Males

and 1 female.

Cepkrenes trichopepla (Lower) 1908, Darwin, N.T., 30-4148, 9-5-48, Females.

Borbo impar lavinia (Waterhouse) 1932. Darwin, N.T., 45-48. 1 male,

Borbo cinnara (Wallace) 1866. Darwin, N,T., 7-5-48, 1 male,

Evans (1949) separates the species of the B. cinnara group from Pelopidas

Walker 1870.

Pelapidas agna dingo Evans 1949. Darwin, N.T., 1-5-48. 1 male.

Rothschild (1915, Novit. Zool., 22, (3):400) showed that Parnara mathias

of Waterhouse and Lyell (1914, Butt, of Australia: 212, 35, £. 711, 712, 713)

was not true P, mathias Fab., but a larger, quite distinct species. Specimens from

Queensland in the British Museum were noted as agreeing with examples from

Dampier and Vulcan Islands, so Rothschild named this species Parnara lyelli.

Waterhouse and Lyell’s figures of P, mathias were given as synonymous, although

Ruthschild’s type male came irom Dampier Island.

Evans (1937), Entomologist 70:65, 66, 81, later showed that true

P. mathias does not occur in Australia, the specimens hitherto known as P. mathias

are referable to two species, P. lyellt Roths. and the south-eastern race of P. agna

Moore. Evans placed the Australian form of P. agna under s. sp. parvimacula

Roths., which was based on a male from Dampier Island. Fvans (1949) now

sinks the name P. parvimacula Roths. as a synonym of Pelopidas mathias repetita

Butler, from New Guinea and the islands and names the form of P. agna which

flies throughout New Guinea, the satellite islands and North Australia, s. sp.

dingo.

I can but follow Evans, who has had access to the types in the British

Museum. The name “dingo,’ based on a male from New Guinea, is a most un-

fortunate choice, since if the Australian form is found to be distinct at some

time in the future, the inappropriately named s.sp. dimgo will be restricted to

New Guinea, though perhaps from an Australian view the name will be well lost,

considering its common Australian connotation,

Regarding the published figures, some confusion is evident as to the species

to which Waterhouse and Lyell’s figures 711, 712, 713 should be referred. Roth-

schild (1915) placed all three figures under P. lyelli Roths, Evans (1937),

discussing P. lyelli, says of these figures, “the male . . . represents a dark form

of this species.” Waterhouse (1937, Proc, Linn. Soc. N.S.W., 62 (3/4); 119),

following Rothschild, refers fig. 711-713 to P. lyelli, but Evans (1949) now places

fig. 711, 712 under the agna s.sp., making no mention of fig. 713, which pre-

sumably remains unquestioned P. [yelli Roths. The matter can only be settled

by reference to the actual specimens from which the figures were taken.

The figures in Waterhouse (1932, What Butterfly is That? 34, f, 10, 10 A)

(misquoted by Evans as 11 fema'e, which is B. impar lazjnia) are unquestioned ;

pl. 34, f. 10 male is the greenish P. agna form, 34, £. 10 A female is P. /yelli Roths.

This specimen is the first recorded from Darwin, hitherto the species has

only been noted from North Queensland,

I am indebted to my friend F, M. Angel for the opporttinity to examine this

interesting little collection of Hesperiidae from the Northern Territory, and the

Directors of the Australian and South Australian Museums for the loan of

material,

ADDITIONAL NEMATODES FROM AUSTRALIAN FISH

BY T. H. JOHNSTON AND P. M. MAWSON

Summary

Parasites from 12 marine host species (including seven elasmobranchs) and 13 freshwater species

(most of them from the Lower Murray River, South Australia, are referred to. Accounts are given of

Terranova galeocerdonis (Thwaite) from Orectolobus maculatus and Stegostoma tigrinum from

Queensland, and Sphyrna lewini from South Australia; larval Contracaecum spp., probably larvae

of C. spiculigerum and C. bancrofti, are reported from 13 species of freshwater fish; C.

(Thynnascaris) legendrei from Promicrops lanceolatus (Queensland) and Caranx georgianus (South

Australia); Acanthocheilus bicuspis from Halaelurus vincenti (South Australia); larval Stomachus

sp. (marinus) from additional hosts, Istiompax australis, Trachurus declivis, Sphyrna lewini and

Notogaleus australis; Goezia fluviatilis in its larval or adult stage in many species of freshwater fish

(Lower Murray River), the larvae often becoming encysted and destroyed in the omentum.

Proleptus urolophi n. sp. from Urolophus testaceus differs from other species in its dentition and in

the more anterior position of the vulva. Capillaria orectolobi n. sp. is described from Orectolobus

devisi. Eustrongylides gadopsis (probably the larva of E. phalacrocoracis from Australian

cormorants) is reported from a large number of freshwater fish from New South Wales, South

Australia and Western Australia.

ADDITIONAL NEMATODES FROM AUSTRALIAN FISH

By T. H. Jounsron and P. M. Mawson*

[Read 10 August 1950]

SUMMARY

Parasites from 12 marine host species (including seven elasmobranchs) and

13 freshwater species (most of them from the Lower Murray River, South Aus-

tralia, are referred to. Accounts are given of Terranova galeocerdonis (Thwaite)

from Orectolobus maculatus and Stegostoma tigrinum from Queensland, and

Sphyrna lewint from South Australia; larval Contracaecum spp., probably larvae

of C. spteuligerum and C. bancroftt, are reported from 13 species of freshwater

fish; C. (Thynnascaris) legendrei from Promicrops lanceolatus (Queensland)

and Carana georgianus (South Australia) ; canthocheilus bicuspis from Halae-

lurus vincenti (South Australia) ; larval Stomachus sp. (marinus) from additional

hosts, [stiompax australis, Trachurus declivis, Sphyrna lewini. and Notogaleus

australis; Goesia fluziatilis in its larval or adult stage in many species of fresh-

water fish (Lower Murray River), the larvae often becoming encysted and

destroyed in the omentum. Proleptus urolopht n, sp. from Urolophus testacens

differs. from other species in its dentition and in the more anterior position of the

vulva. Capillaria orectolobi n.sp. is described from Orectolobus devisi,

Eustrongylides gadopsis (probably the larva of E. phalacrocoracis trom Austra-

lian cormorants) is reported from a Jarge number of freshwater fish from New

South Wales, South Australia and Western Australia,

The specimens examined were collected chicfly by the senior author, but we

are indebted to Professor J, B, Cleland for some from Encounter Bay; Mr. H,

M. Cooper for material from Caranx and Trachurus from St. Vincent Gulf;

Mr. G. G, Jaensch for assistance at Tailem Bend; Dr. A, G. Nicholls and Mr. B.

Shipway, C.S.LR.O, Fisheries Division, for Western Australian material; and

Mr. J. 8. Lake of Sydney for material from trout in New South Wales,

HOST-PARASITE LIST

Marine FisH

QrectoLopus MacunaTus Bonnaterre. Terranova galeocerdonis ‘Thwaite,

Caloundra, South Queensland,

OrecroLogus pevis1 Ogilby. Capillaria orectalobi n. sp., Port Willunga, S, Aust.

This shark is not mentioned hy Whitley (1940, 81), but he republished

Waite’s (1923, 33) figures of it under Q, ornatus halet, the Gulf Wobbegong.

STEGOSTOMA TIGRINUM Pennant. Terranova galeocerdonis Thwaite,’ Moreton

Bay, South Queensland.

HALAELURUS VINCENTI Zietz (Jincrus vincenti m Whitley, 1940). Acantho-

cheilus bicuspis Wedl, St. Vincent Gulf, S. Aust.

SPHYRNA LEWiINI Griffith, Stomachus sp. larva; Terranova galeocerdonis

Thwaite, Encounter Bay, S. Aust,

NorocGALeus AusTRALIS Macleay, Stomachys sp. larva, Moreton Bay, South

Queensland.

Urovorius Testaceus Mull. and Henle, Proleptus urolophi n.sp., Sydney dis-

trict, New South Wales.

ProMicrops LaNceGLatus Bloch, Contracaecum (Thynnascaris) legendre; Dell-

fus, Caloundra, Sottth Queensland.

University of Adelaide.

Trans, Roy Sec. §. Aust, 74, (1), March 1951

ScraENA ANTARCTICA Castln, Contracaecum (Thynnascaris) legendrei Dollfus,

Caloundra, South Queensland, and Kiama, New South Wales,

IstromPax AUSTRALIS Whitley. Stomachus sp, larva, Mentone, Port Phillip,

Victoria.

Caranx Ghorcranus C, and V. Contracaecum (Thynnascaris) legendret Doll-

fus, larva, Outer Harbour, St. Vincent Gulf, South Australia.

Trachurus peciivis Jenyns, Stomachus sp. larva, Rapid Bay, South Australia.

FRESHWATER FisH

McCuLtocHELta macguariensis C. and V, Goesia fluviatilis J, and M., adult

and latva, Murray River, South Australia.

PLECTROPLITES AMBIGUUS Richdsn. Goésia fluviatilis J. and M. adult and larva,

Murray River, South Australia.

PERCALATES coLoNoRUM Gunther. Contracaecunt sp, larva, Murtay River, South

Australia.

THERAPON BIDYANA Mitchell, Goesia fluviatilis J. and M., larva, Murray River,

South Australia.

TANDANUS TANDANUS Mitchell. Goezia fluviatilis J. and M., larva, Murray River,

South Australia,

PSEUDAPHRITIS URVILLII C. and V. Goesia fluviatilis J. and M. larva; Contra-

caecum sp,, larva; Murray River, South Australia. Eustrongyhdes gadopsts

j. and M., larva, Coorong, South Australia, The congolli does not now

shape the Murray from the sea because of the barrage near the entrance to

the river.

RETROPINNA SEMONI Weber. Goegia fluviatilis J, and M., larva; Contracagcum

a 2 ;

sp., larva; Murray River, South Australia.

NANNOPERCA AUSTRALIS Gunther. Goezia fluviatilis J. and M., larva; Contra-

caecum sp., larva; Murray River, South Australia.

Nawnoperca (Eperta) virrata Castln. Ewustrongylides gadopsis, larva, South-

western Australia.

Puinypnopon cRANnpicers Krefft. Goesia fluviatilis J, and M. larva, Murray

River, South Australia,

Carassiops KLUNZINGERI Ogilby. Goesia fluviatilis J, and M., larva; Eustrongy-

lides gadopsis J. and M., larva; Contracaecum sp., larva; Murray River,

South Australia,

SaLMo TRUTTA Linn, Eustrongylides gadopsis J. & M., larva, from various locali-

ties in New South Wales,

SALMO GAIRDNERT, LEustrongylides gadapsis J. & M,, larva, Blackwood River,

Sieeown; Western Australia; and from various rivers in New South

ales,

The names applied to the species of trout acclimatized in Australia and New

Zealand are confusing, The brown trout has been called Salmo trutta, S. eriox

and S, fario,; the rainbow trout, S, irideus, S. gairdnerii and S. gairdnerit gilbert

(McCulloch, Fishes of New South Wales, 1922, 18-19 ; 1934, 18-19; Mem.

Austr. Museum, 5 (1), 1929, 45, Waite, Rec. South Austr, Museum, 2 (1),

1921, 6; The Fishes of South Australia, 1923, 234. Stead, Fishes of Australia,

1906, 33-36. Hobbs, Trout Fisheries of New Zealand, N.Z. Marine Dept,. Bull. 9,

1948, 5-6. Also Snyder, The Trouts of California, 1940). Mr. J. S. Lake,

Biologist to the Fisheries Branch, New South Wales, in a letter dated 3 August

1950, stated that, until 1946, the river brown and tainbow trout were known

as S. fario and S. irideus respectively; and the sea run types of these two as

S. trutta and S. gairdnerii respectively ; but that they are now regarded as belong-

ing to S. trutta and S. gairdnerii, whether sea run or not; and these are the only

two species which haye become acclimatized in Australia, We have accordingly

adopted the specific names accepted by Mr. Lake.

TERRANOVA GALEOCERDONIS (Thwaite)

Fig. 1-4

This species, originally described from Galeocerdo tigrinum from Ceylon,

has now been recognised from two carpet shatks from Southern Queensland,

Stegostoma tigrinum from Moreton Bay, and Orectolobus maculatus from

Caloundra, as well as from the hammer-head shark, Splhyrna lewini, from En-

counter Bay, South Australia,

Fig. 1-7

Fig. 1-4, Terranowa galeocerdonis—i, anterior end; 2, head; 3, lateral, and

4, ventral, views of male tail, Fig. 5-6, Proleptus wrolophi—s, section through

anterior end showing inside of pseudolabium; 6, ventral view of tail of young

male. 7, Capillaria orectolobi, male tail. Fig. 2, 3, 4 and 6 to same scale

(beside fig. 6).

In our material the males are up to 32 mm. in length; the females to 44 mm.

The oesophagus is 1:12-14 of the body length, its ventriculus a quarter of the

total oesophageal length, and the intestinal caecum about twice the length of the

ventriculus. The ratios of these parts are not given by Thwaite, but assuming that

the lower figure in each range of measurements given by him refers to the shortest

wortns, and the higher to the longest worms, the agreement between our specimens

and T. galeocerdonis is close. The eggs in the Australian specitnens are 32-36 in

diameter, not 41 as recorded by Thwaite. The form of the postanal structure in

the male appears to be that of a cuticularised plaque, the lateral edges of which are

prolonged into an irregular series of spines, Of the caudal papillae, there are in our

specimens two median preanal situated one behind the other in the projecting lip

of the anus, and we were able to detect only two pairs, instead of three, close to

the tip of the tail, In spite of these differences we consider that our specimens

fall within the species T. galeocerdonis,

It may be noted that in some latval Terranova sp. studied recently by us

from an unknown fish host forwarded by the Australian Museum, the proportions

of the parts of the alimentary canal resemble those of this species, and it is pos-

sible that they represent its larval stage.

ConTRACAECUM spp. (larvae)

Glassy transparent larvae of species of Contracaecum s, str., have been found

not uncommonly in elongate cysts in the omentum or mesentety of various fresh-

water fish from the Murray River, between Swan Reach and Tailem Bend, These

larvae vary considerably in length due to age, They no doubt belong to C. spicn-

ligerum and/or C. bancrofti which are common in cormorants and pelicans respec~

tively in the swamps and along the river in the region mentioned. The tail of

these larvae is devoid of spines and the oesophagus does not possess a well-defined

bulb, thus indicating that it belongs to the sttbgenus C. (Contracaecum), The

cysts when older tend to become thicker walled and brownish, but they do not

usually invest closely the enclosed worms which can move readily within them,

We (1947, 551) have already recorded the occurrence of these larvae in Plectro~

plites ambiguus, MecCullochella macquariensis, Therapon bidyana, Philypnodon

grandiceps, Tandanus tandanus, Galaxias olidus, Nannoperca aystralis, Nematalosa

erebi, and Mugilogobixs galwayi trom the Murray River in the vicinity of Tailem

Bend, We now record finding them in Retropinna semoni, Carassiops klunzingert,

Pseudaphritis urvillii and Percalates colonorum from the lower Murray,

ContracaEcuM (THYNNASCARIS) LEGENDREX Dollfus

‘This apparently widespread parasite of marine fish is now recorded as

occurring in its adult stage in a Queensland groper, Promicrops lanceolatus, from

Caloundra, South Queensland, and in Sciaena. antarctica from Caloundra and also

from Kiama, New South Wales. Immature worms wete Sound in Coranr

georgianus from St, Vincent Gulf, South Australia. We (1945, 133) had pre-

viously recorded the presence of the larva from the latter species of fish from

Tasmania.

ACANTHOCHE!LUS BicusPis (Wedl 1855)

This species is recorded from the cat-shark Haloelurus wincenti, from

St. Vincent Gulf, South Australia. It has previously been recorded by us (1945,

107) as A, guadridentatus (Molin) from Mustelus antarcticus from various

parts of the Australian coast, We follow Punt (1941) in referring the worms

to the specific name, bicuspis Wedl.

STOMACHUS sp, (MARINUS) larvae

The following species of marine fish are added to the long list of hosts from

which Stomachus sp, larvae are recorded:—the marlin,[stiompax australis, from

Mentone, Victoria; 7rachurus declivis, Rapid Bay, South Australia; the hammer-

head shark, Sphyrna lewini, from Encounter Bay, South Australia; and the

school-shark, Notogaleus australis, from Moreton Bay, Queensland.

Dollfus (1948) has drawn attention to the fact that the ventriculus may be

either straight or sigmoid in the adult stages of Stomachus, for which genus he

still retains the name Anisakis. His host list refers only to adult stages recorded

from Cetaceans and Pinnipedes.

GOEZIA FLUVIATILIS Johnston and Mawson

In our original account (1940, 342) we recorded finding the adult stage of

this short plump spiny worm in the digestive tract of Plectroplites ambiguus,

McCullochella macquariensis and Percalates colonerwm from Tailem Bend; and

immature stages in Nannoperca australis and Tandanus tandanus frony Tailem

Bend, as well as in Mogurnda adspersa trom the upper Burnett River, Queens-

land. Later (1947, 552) we reported it from Plectroplites ambiguus from the

Thompson River, Central Queensland; and larval stages from Percalates

colonorum, McCultochella macqueriensis and Tandanus tandanus from Tailem

Bend, South Austratia,

Larvae have since been found encysted in the omentum and mesentery of

the following additional species of fish in the lower Murray region (South Aus-

tralia) :—Ketropinna semoni; Carassiops klungingeri; Philypnodon grandiceps ;

Pseudaphritis urwllit; Therapon bidyana; and Plectraplites ambiguus, It is of

interest to note that both larval and adult stages may occur in the same species of

percoid fish, e.g., MeCullochella, Percalutes and Plectroplites,

The youngest stages seen were found apparently free in the body muscles—

perhaps indicating a wandering stage before settling down in their usual habitat in

cysts im the omentum, These very small larvae were found in Carassiops and

Xetropinna. Another of similar size was found amongst muscle fibres of the

teased body of Philypnodon grandiceps, but fragments of thin connective tissue

were adhering to it, hence it is possible that these tiny worms from the three hosts

mentioned may have come from the mesentery or omentum and were in process

of becoming encysted. The specimens from Carassiops and Refropinna were bent

dorsally into an open U, while one from Philypnodon formed two spirals, The

worms from these three hosts measured *87-'97 mm. long, with a fnaximim

brendth of -077-"09 mm, The body was widest in the anterior two-thirds, very

gradually narrowing towards the anal region, when the tapering became more

pronounced, The very short tail was bluntly rounded. The distance between

the anus and the tip of the tail was -055 mm. The lips were well developed, as

was the spination on the anterior two-thirds of the body, but the series of spines

‘became very low in the succeeding region, and then practically disappeared, but

spines could be seen quite definitely on the ventral surface of the tail, ‘The

oesophagus measured 0'158 mm, long (= 1:5°5 of body length), its diverticulum

(which is relatively extremely long and about three times the. oesophageal length)

0'44 mm., and the short intestinal crecnm ‘03 mm.

The larvae previously described by us were an encysted larva 1°35 mm. long

and another 2°8 mm. in length from the omentum of Nannaoperca australis

(Tailem Bend) and Mogurnda adspersa (Burnett River, Queensland) respec-

tively.

A degenerating larva from Twndanus was coiled within a round, rather flat

eyst with its head lying across the rest of the body, the cyst being ‘31 mm. in

diameter, and closely investing the worm. In another from the same host the

cyst was morte dense, *36 mm, in diameter, and the worm more degenerated. —

In the Murray cod, McCullochella, we have met with many degenerating

cysts on various occasions and tisually the enclosed worm is no longer recognisable,

The Goesia worm or ils remnant was seen to be more or less straight, curved,

partly coiled or irregular; and the inner part of the cyst was very dense when

degeneration was more ot less complete. Two small round cysts measured

-33 mm, and “44 mm, in diameter, the outer zone consisting ot rather clear

fibrous tissue, the denser region enclosing the worm being "19 by 16 and °24

by -26 mm. respectively. Much smaller cysts were also present but the identifica-

tion of the causative worm was not possible, In one case the cyst measured

‘66 by 17 mm. and the contained worm -46 by -11 mm.; in another cyst ‘77 hy

‘27 mm., the degenerating worm measured ‘44 by “28 mm. In other cases the

cyst was much longer and was irregular but the parasite could not be recognised

and may have belonged to a quite different species,

Similar degenerating Gocsia cysts were seen in Plectroplites, Therapon

bidyana and Pseudaphritis wyvillit, The last-named fish, the congoli, is anadrom-

ous and is not now found in the Murray River since the barrage at its entrance

has been completed, the fish now heitig found in the neighbouring Coorong.

Proleptus urolophi n. sp.

Fig, 5-6

From a stingray, Urolophus testaceus, irom Port Jackson, New South Wales.

Numerous specimens ate present. Males up to 9°6 mm, in length; females to

17°5 mm, Cuticular collar more or less pronounced according to age and state

of contraction of the worm. Pseudolabia each with two external papillae and five

interna) teeth of which the median is truncated and the two outer pairs conical.

The anterior part of the oesophagus is narrower than the posterior; and is

-33--4 mm. long in the male, -4-"5 mm. long in the female, and is surrounded just

posterior to the mid-length by the nerve ring, The excretory pore is a trans-

verse cuticularised slit at about the junction of the two parts of the oesophagus.

ae osterior oesophagus is 1-1-1-3 mm, long in the male, 1-4-1:7 mm. in the

emale,

Female—Tail an elongate cone, usually dorsally directed. Vulva shortly

bets oesophageal region, 2-6-3-4 mm. from head, Eggs 20 by 40p, with thick

shells:

Male—Alae more in the form of bulbous expansions of the cuticle than mem-

branous wings, and riot meeting anteriorly or posteriorly, Ventral surface of the

precloacal region with longitudinal circular ridges. Three pairs of pedunculate

preanal papillae, three median papillae on the anterior lip of the cloaca, four pairs

of pedunculate postanal papillae, and almost at the tip of the tail a pair with

inarkedly expanded peduncles. Fig. 6 is of a young male; in older specimens

the posterior end is coiled into two or three tight spirals. The shorter spicule is

‘18- 2 mm. long, its tip sometimes protected by a membranous “sheath”; the longer

spicule is acicular, about ‘95 to 1-2 mim. long.

The species appears on general characters of the head and male tail to fall

into the genus Prolepius. However, the position of the vulva is more forward

and the dentition is different from that present in any other species of the genus

of which we have scen a description, We have been unable to obtain an account

of P. anabantis Pearse 1933,

A useful review of the various species attributed to the genus was given by

Baylis in 1933. In his description of P, australis he states that the host was a

“tiger shark” (probably Galeocerdo tigrinus) from North Queensland.

Capillaria orectolobi n. sp.

Fig. 7 -

One whole mate and a part of another male worm belonging to the genus

Capillaria were taken from a carpet shark, Orectolobus devisi, from Port Willunga,

South Australia, The length of the whole male is 15:3. The cells of the oeso-

phagus are indistinguishable. The oesophageal region, 7:3 mm. long, occupies

about half the body length. The alate spicule is 10:1 mm, in length, and its sheath

is spinose, The bursa is very small, with one papilla at each side. Bacillary

hands appear to be absent from the cuticle.

EusTRONGYLIDES GaADoPsIs J, and M.

Additional hosts for the larval stage:—a carp gudgeon, Carassiops klunzin-

geri, from Tai‘em Bend; congolli, Pseudaphritis urvillii, Coorong, South Australia

(J. Kimber) ; western pigmy perch, Nannoperca (Edelia) vittaia, South-western

Australia (B. Shipway); brown trout,Salmo truita, New South Wales rivers;

rainbow trout, S. gairdneri, Blackwood River, Bridgetown, Western Australia

(Dr. A. G. Nicholls); also from the New England area, Macdonald River,

Major’s Creek (Central Western New South Wales), Sodwalls Creek, Little or

Retreat River, Monaro district (especially the headwaters of the Lachlan River),

all of these localities being in New South Wales (J. S. Lake). Other Aas-

tralian fish hosts for the larva have already been recorded by us (1940, 350; 1944,

64; 1047, 548).

The presence of the adult stage, described by us as E. phalecrocoracis, in

cormorants in New South Wales and Western Australia may be inferred.

LITERATURE

Bayuis, H.A. 1933 On the nematode genus, Proleptus. Ann, Mag. Nat. Hist.

(10), 12, 325-335 .

Dotirus, R. P. 1948 Nématode 4 oesophage sigmoide de l’estomac d'une Orca

orea, etc. Ann. Parasit., 23, 305-322

Jounston, T. H: and Mawson, P. M. 1940 Some nematodes from Austra-

lian freshwater fish. Trans. Roy. Soc. S. Aust., 64, 340-352

JosuNnston, T. H., and Mawson, P. M. 1944 Remarks on some patasitic

nematodes from Australia and New Zealand. Trans. Roy. Soc. S, Aust.,

68, 60-66

Jounston, T. H., and Mawson, P.M. 1945 Parasitic nematodes. B.A.N-Z,

Antarct. Res. Exp, Rep., B, 5, (2) 73-160

Jounsron, T. H., and Mawson, P. M. 1947 Some avian and fish nematodes,

paedy from Tailem Bend, South Australia. Rec, 5. Aust, Mus., 8, {4},

47-553

Pearse, A. S, 1933 Parasites of Siamese fishes and crustaceans. Jour, Siam.

Soc., 9, 179-191

Punt, A, 1941 Recherches sur quelques nématodes parasites. Mem. Mus Roy.

Hist. Nat. Belgique, No, 98, 110 pp.

Tawarte, J. W. 1927 On a collection of nematodes from Ceylon. Ann. Trop.

Med, Parasito]., 21, 225-244

Warts, E.R: 1923 The fishes of South Australia. Govt. Printer, Adelaide

Weittey, G. P. 1940 The fishes of Australia. Pt, 1, The sharks, etc., Roy-

Zool, Soc. N.S.W.

GEOLOGY OF THE PIDINGA AREA

BY D. KING

Summary

A complete succession of marginal sediments of the Nullarbor Plains Basin which occur in and

adjacent to the Pidinga Lakes were carefully mapped and sampled, and Part I deals with the

geological findings. The lower beds are of lacustrine origin and include lignitic and alunitic clays.

These are overlain by Middle Miocene marine limestone. Siliceous and ferruginous laterites,

forming a capping in some areas, are believed to have developed in Pliocene times.

GEOLOGY OF THE PIDINGA AREA (!)

By D. Kine*

[Read 10 August 1950]

SUMMARY

A complete succession of marginal sediments of the Nullarbor Plains Basin

which occur in and adjacent to the Pidinga Lakes were carefully mapped and

sampled,.and Part I deals with the geological findings, The lower beds are of

lacustrine origin and include lignitic and alunitic clays, These are overlain by

Middle Miocene marine limestone. Siliceous and ferruginous laterites, forming

a capping in some areas, ate believed to have developed in Pliocene times.

Precambrian gneisses also outcrop over a large area in the vicinity of Pidinga.

Part II is a detailed petrological study of the gneisses.

The geological plan of the Pidinga area was constructed by compass and

chain traverses, and is accurate to within the limits permitted by this method.

The plan shows only actual rock outcrops or geological data obtained from

nak WULLARBOR ' PLAIN *

me Lake Taltacoatra '

AUSTRALIAN

Flog»

PIDINGA AREA

LOCALITY PLAN

MILES 25 4100 MILES

a rt cl td

PREVIOUS REFERENCES

The geology of this region has received very little attention in the past

due to the lack of transport facilities and water supplies, and the great dis-

tances between rock exposures.

@) Portion of a thesis submitted for the Degree of Master of Science at the Uni-

versity of Adelaide.

*Agsistant Geologist, Department of Mines.

Trans, Roy Soc. 5S, Aust., 74, (1), March 195]

Brief references to the physiography and prevailing rock types of the

area appear in the published accounts of eatly South Australian explorations,

among which the reports of Tate (1878), Jones (1880), Giles (1889) and

Brown (1885 and 1898) are the most notable. Specialised investigations of

shallow lignite and a recently discovered alunite occurrence at Pidinga are

referred to in the publications of the South Australian Department of Mines.

PHYSIOGRAPHY

Pidinga is situated 39 miles south of Ooldea, a siding on the trans-con-

tinental railway, in the far western portion of South Australia. At Pidinga

there is a series of dry saline lagoons situated in a broad depression forming

the eastern boundary of the vast Nullarbor Plain. Broadly speaking, the

eastern margin of the plain comprises a series of such shallow depressions

with chains of lakes, The lakes generally contain outcrops of Precambrian

and/or Tertiary rocks which are elsewhere in this region obscured by a thin

mantle of soil or drift sand,

The Main Pidinga Lake is elongated in a N.E.-S.W. direction, measuring

14 miles in length and with an average width of one quarter of a mile, parallel

ta a ridge of bare hills on the western flank. These rise about 100 feet above

the level of the lake and 30-50 feet above the adjacent Nullarbor Plain. A

typical panorama across portion of the lake is shown in pl. II, fig. 3. The

ridge is much dissected on the eastern side, with numerous creeks draming

easterly into the lake, the edge of which is often sharply defined by low cliffs.

The western flank of the ridge smooths owt gradually and merges into the

Nullarbor Plain. The ridge comprises gneissic Precanibrian rocks.

The greater part of the eastern margin of the lake is defined by sandhills

or flour gypsum dunes, beyond which is broadly undulating country with a

travertinous soil and thick herbage of myall, mulga, sandalwood and quon-

dong. There is very little surface drainage into the lake on its eastern margin.

The Main Pidinga Lake, and other small lakes in the vicinity, which are

linked to one another by partly drifted and vegetated depressions, have an

ill-defined drainage in a southerly direction, The lake narrows out in the

south-western portion to a mere watercourse about 50 yards wide, covered

with a silty soil and thickly timbered with mallee, ti-tree and myal!. This

watercourse ends abruptly in an extensive timbered flat surrounded by lime-

stone cliffs about 12 feet high (plate II, fig. 4), beyond which ts the Nullarbor

Plain proper,

It is considered likely that the ancient watercottse recognised at Pidinga

was very active during the high rainfall conditions of the Pleistocene period

responsible for the excavation by solution of the extensive caverns of the Nul-

larbor Plain limestones (King, 1949). Moreover, as the Main Pidinga Lake

ends suddenly in a large depression resembling a sink-hole, surrounded on

three sides by the Nullarbor Plain, present day floodwaters following excep-

tional rain, in all probability, still continue to pass underground into the

porous chalky limestone below the plain at this point. In other words, this

southern extremity of the Pidinga Lake is still an intake source for the

ground water of the Nullarbor Plains Basin.

PART I—THE TERTIARY SEDIMENTS

During early Tertiary time, shallow freshwater sediments, including

lignites, were deposited in surface depressions in the Precambrian shield. The area

to the west of Pidinga, now defined by the Nullarbor Plain, was a notable

depression in which the lacustrine conditions were followed by an invasion of the

sea, resulting in the deposition of a thick bed of polyzoal limestone, Marine cor

ditions prevailed until the Middle Miocene, when a shallow sea covered the

Fidinga area. The Tertiary sediments at Pidinga, both fresh-water and

tnarine, show considerable variations laterally as would be expected under

shallow water conditions. The general stratigraphic succession of the heds,

which are normally horizontal, is shown in Diagram No. 3.

The Oligocene ‘®) Ligiitic Series — Lacustrine

The earliest reference to the occurrence of lignite at Pidinga was made

by the former Government Geologist, H.Y.1.. Brown, in the year 1885.

Brown reported that a trial bore had been sunk into the lake by a Mr, Ifould,

with the following results; 0-30 lignite: 30-39 grey clay and ironstone: 39-40

lignite, The approximate location of the bore is shown on the geological

map (Plan No. 2).

Further recent exploratory work on the lake has revealed that an area

of approximately one square tile is underlain at shallow depth by a

bed of low-grade lignite, ligneous sand and clay. Actual brown coal was found

within three feet of the surface, A borehole (No, P15) sunk by the Depart-

tnent of Mines in 1948 to test the thickness of the coal and obtain reliable

samples for analytical purposes penetrated 45 feet of carbonaceous material

above grey clay. The bore was not continued to bedrock. Analyses of vari-

ous horizons disclosed that even the most promising of the lignite was

very high in ash, Irregular masses of pyrites intergrown with lignite were

observed in the lignitic sand between 364 and 414 feet. Another constituent

ot the lignite is fossil resin. Sampies from this borehole were sent to the

C.S.LR.O. Pollen Research Laboratory at the Melbourne University and the

following observations were made by Miss K. M. Pike, B.Sc. (1949}.

“The clay shows a rich assemblage of pollen and spores, representing the

families: —Proteaceac, Myrtaceae, Epacridaceas, Fagaceoe, together with

other Gymnosperms, and fern spores. A comparison made with preparations

from Moorlands brown coal reyealed that many of the pollen and spore types

were present in both coals, except that Myriaceae appear to be absent from

the Moorlands coal, There is thus a suggestion that the Pidinga deposit

might be of the same general age as Moorlanis.”

The early Tertiary age of the beds thus indicated by pollen and spore

determinations is supported by stratigraphic considerations. The following

section was obtained by sinking a trial auger hole (Section No. 1 on the geo-

logical plan) at the foot of the cliffs in an embayment on the western edge

of the lake.

feet

QO -— 3. fossiliferous silicified limestone,

3 — 4 off-white gypseous and gritty clay — larpe selenite

Chit crystals.

4 — 9 vyari-coloured ferruginous clay, some ironstone

nodules.

9 -10 red ochreous sand.

10 —J1 red ochreous sand.

11 —113 yellow and white mottled clay.

wae 113-13 yellow ochreous sand.

tay 13 -17 vari-coloured iron-stained sandy clay.

17 —194 yellow ochreous sandy clay.

19$—20 lignitic clay and sand.

@) The Early Tertiary ligoites which occur helow the marine Miocene beds

throughout a large area of southern Australia are generally referred to as of Oligocene

age, Miss. Crespin (1945) considers they are Lower Miocene.

The limestone at the top of this succession contains fossils typical of the

South Australian Middle Miocene.

At another locality (Section No, 2) the lignitic bed underlies cliffs capped

with. porcellanite.

feet

Clit | O — 3 porcellanitic grit and surface quartzite.

3 -— S$ pale coloured sandy clay — mainly white.

Auger { 5 = 8+ pale vari-coloured sandy clay — mostly yellow,

hole 84- 9f carbonaceous clay with fragments of decomposed

wood,

The lignite can be correlated in age and mode of occurrence with that of

Lake Tallacootra, and with another deposit discovered by the writer at Seven

Mile Swamps, about 60 miles south-cast of Pidinga, in the north-western por-

tion of County Kintore. In each of these cases, lignitic clay occurs under

similar circumstances, namely, below the beds of lake depressions of Middle

Miocene limestone. Probably the lignitic clays reported during the coarse of

boring for water at Malbooma (Ward, 1939), situated about 120 miles north of

east from Pidinga, and in a bore sunk by the Commonwealth Railways east of

Ooldea, are also of comparable age.

Lower’ Miocene Shallow Water Sediments — chiefly Lacustrine

These include the unconsolidated beds of soft clay, sand and grit, in part

ferruginous, which occur at and below the surface over large areas in the

Pidinga lakes, and are in many places exposed in the lower levels of the cliffs

fringing the lakes. The sediments are typically a shallow-water suite. The

lower beds are completely unfossiliferous but minute marine orpanisms have

been found to occur in the uppermost horizons. They are tentatively as-

sumed to be of Lower Miocene age as they overly Oligocene lignite and are

capped with Middle Miocene marine limestone. Their deposition, therefore,

was probably contemporaneous, with the polyzoal limestone formation of the

Nullarbor Basin which occurs between the same beds, The porcellanites

which in some places form a capping to the clays, etc., are regarded

as part of the same formation but they ate treated in more detail under a

separate heading, as processes of a later geological period were apparently

responsible for their alteration to a hard dense silicified state. In several

localities the beds shaw pronounced dips which are possibly due to minor

faulting or warping.

A unique but ideal locality for the study of the stratigraphic succession

in these sediments is a small outlier capped by fossiliferous limestone in the

centre of the Main Pidinga Lake (see pl. II, fig. 1). It forms a prominent

landimark and the reason for the preservation of this “island” of unconsoli-

dated sediments, elsewhere eroded to form the Pidinga Lake, is probably the lime-

stone capping having been particularly resistant to erosion, It serves a very useful

purpose in showing a complete succession of strata from the Oligocene lignitic

beds underlying the Pidinga Lake surface to the Middle Miocene fossiliferous

limestone. A trial hole was sunk at the base of the knoll, and on the assumption

that there is no faulting, it was found that about 20 feet of the Lower Miocene

sediments overlie the lignitic beds. The succession (Section No. 3) is as follows:

feet

if QO = 4 fossiliferous limestone — gritty

Clit 4 — 6 yellow and green angular sand and grit

| 6 — 8 white and friable gypseous clay

8 -—14 white and grey clay with patches of iron oxide stains

14-15 fine pale yellow ochreous sand

15 +17 fine pale yellow ochreous sand — patches of white

sandy clay

17 —1934 fine red ochreous clayey sand

193-20 red gritty ferruginous clay

20 -22 grey clay, slightly gritty — some mica flakes

22 ~23 fine white and pale yellow sand

23 —234 bright yellow ochreous fine sand — some mica

234-244 grey and purple sandy clay

244-25 brown catbonaceous sandy clay — some iron-

stained patches

25 —25} red and purple ferruginous sand and grit

254-29 grey and brown carbonaceous clay and sand.

The bed of angular sand and grit directly below the limestone in this

section was observed in several other exposures on the western edge of the

Main Pidinga Lake, where it contained numerous platy crystals of selenite.

Generally speaking, these sediments become increasingly sandy towards

their base and, as in the section quoted, beds of very fine quartz sand stained

with ochre separate clay beds from the underlying lignitic beds. In other

areas, the ochteous sands are absent and the Lower Miocene sediments con-

sist almost exclusively of white and vari-coloured clays. The contact with

the lignitic series is sometimes sharp, but in borehole P15, on the Main

Pidinga Lake, and in other bores on Lake C, the change is gradational with

white clay interbedded with lignite. The contact of the Oligocene and Lower

Miocene sediments cannot be accurately placed in the bore on account of the

overlapping of conditions of deposition of the respective sedimentary forma-

tions. The uppermost appearance of the carbonaceous material is taken as

the top of the Oligocene and this is really the only distinguishing charac-

teristic from the overlying beds.

Another feature of the Early Miocene lacustrine sediments is that they

are lenticular, as if they were laid down on an uneven surface, perhaps

shrunken remnants of the original extensive lake in which the lignite accumt-

lated, Whilst the series is generally unfossiliferous the uppermost bed has

indications of a marine radiolarian (genus Cenosphaera) determined by Miss

I. Crespin. Although Miss Crespin suggests from a laboratory study (Rock

No. 146) that the radiolarian may be a Cretaceous form, the field evidence

cannot in any way support this conclusion as these particular beds are de-

finitely underlain by Oligocene lignite and overlain by Middle Miocene lime-

stone, both fossiliferous. The presence of a marine fossil in the uppermost

bed probably represents the beginning of the marine incursion which re-

sulted in the deposition of the Middle Miocene limestone.

It may be noted here that a feature of these sediments is their alunitic

character. In some localities they contain such a high proportion of avail-

able potash as to be classed as a commercial alunite. This property is te-

garded as having been acquired and not of syngenetic origin. In their origi-

nal state, the clays probably represent a normal accumulation of kaolinitic

decomposition products from the weathering of the feldspathic gneiss rocks.

Apart from the disseminated ochreous stains which characterise this

formation as a whole, there are commonly developed, within the upper hori-

zons of the clay, nodules or discontinuous flat beds of a fetruginous siliceous

nature, That these are of secondary origin and caused by similar alteration pra-

cesses, namely lateritization, as those responsible for the induration of the porcel-

lanites and surface quartzites discussed later, is indicated by the study of a

thin-section. Rock No. 138 is a very fine-grained red-brown, siliceous rock.

The section consists of a fine even-grained meshwork of quartz in which

individuals are clear hexagon-shaped erystals of secondary origin, and with

vari-coloured iron oxide as the cement.

Middle Miocene Fossiliferous Marine Limestone,

Isolated outcrops of coarse crystalline limestone occur at numerous points

along the western margin of the Pidinga Lake. Typical successions capped with

limestone haye already been quoted (Sections Nos, 1 and 3), and the latter is

reproduced in pl. II, fg. 1, The bed is only a few feet in thickness and in general

forms a capping over the Lower Miocene sands and clays previously described, or

decomposed bedrock gneisses. The limestone is highly silicified and commonly

stained with yellow and brown tinges of iron oxide, An abundance of rounded

quartzose pebbles and grit within the matrix of the limestone, and the unusually

large size of many of the included fossils, are indicative of littoral conditions, as

would be expected m the neighbourhood of the protruding older racks.

In the more westerly of the lakes, and at the south-western extremity of the

Main Pidinga Lake, the limestone is of greater thickness and the underlying beds

are not exposed. West of the eroded area, the limestone occurs again beneath a

mantle of soi] and travertine rubble, as. part of the upper “hard ecrtist” of the

Nullarbor Plain. On the north-eastern edge of the lake, and beyond, the under-

lying rocks are obscured by a coverage of sand and loam and there are no lime-

stone outcrops, but when due consideration is given to the relative levels, ir is

suspected that the shallow sea did extend much further east than Pidinga.

The limestone is notably rich in fossil] casts of large shells. Notable fossils

are Marginopora vertebralis and WNetowola subfossilis, Thin-sections of

the limestone were studied by Miss I. Crespin (Report No. 4949/93). The

assemblage of micro-fossils was found to be almost identical with that in samples

of the surface rocks from the Nullarbor Plain (King, 1949). Micro-palaconto-

logical descriptions of individual samples are as follow -—

Rock No. 19. A hard silicified foraminiferal limestone.

Plantae—Lithothamninm ramosissimunt,

Foraminifera—Marginopora vertebralis; Quingueloculina sp, Trtlocu-

lina tricarinata, Valvulina cf, fusca; Small miliolidae indeterminate.

Rock No, 115, A hard silicithed foraminiferal limestone.

Foraminifera—Austrotrillinag howchints Bolivinella cf, folia; Cibicides

refulgens; Elphidium cl, adelaidensis; Margitapora vertebralis;

Planorbuling mediterranensis; FRotalia cf. calcar; Triloculina tri-

carinata; small miljolidae; small rotalines,

Rock No. 135, A coarse shelly sandstone with broken tests of foraminifera,

including Marginopora vertebralis,

Tn a summary, Miss Crespin writes :—

“Rock No. 135 is a shelly sandstone containing Marginopora vertebralis.

The rock is regarded as Lower Pliocene in age and as an ¢quivalent of the

fossiliferous beds at Hallett’s Cove, south of Adelaide, and of the *“Adelai-

dean' deposits which underlie the Adelaide Plains.

Rocks Nes, 19 and 175 represent the Middle Miocene limestone which

is typical of many outcrops west of Adelaide, especially on the Nullarbor

Plains. Austrofrillina howchint is common in Rock No. 115 where it is

associated with Marginopora vertebralis, Although Austrotrillina howechint

is not present in the two small sections of No. 19 sent for examination, the

lithology and mode of preservation of the foraminifera suggest if further

sections were available this form would be found.”

In view of the relatively small thickness and homogeneity of the formation,

and the presence of the Middle Miocene index fossil Austrotrillina fowehini, it

may best be regarded as entirely of Middle Miocene age,

Derivation of the Porcellanites or Siliceaus Laterites,

The crust of dense porcellanite which forms a capping to a number of the

outcrops of soft clay and sand, etc., was probably formed under similar climatic

conditions to that which produced the siliceous laterites covering the surface of

large areas of the Australian Tertiary peneplain, These have been regarded as

fossil soils due to leaching and chemical redistribution of mineral matter in solu-

tion during a period, or periods, of hutmd and high rainfall conditions, and are

generally referred to as the “Duri-crust,”

The sedimetits which have been silicified at Pidinga are no exception to this

condition of formation and originally comprised clay, sand or grits from the upper

horizons of the Lower Miocene shallow-water sediments. In other places in the

vicinity of the lakes the same beds, but not indurated, are overlain by

Middle Miocene marine limestone. A section exposed in a cliff on the western

edge af Lake C (Section No. 4 on the geological plan) is typica) of these in which

porcellanite is present.

feet

QO — 4 white porcellanised claystone, heavily iron-Stained.

4 — 9 white sandy alunitic clay — soft,

9-11 yellaw ochreous sandstone.

11 plus white gritty alunitic clay.

A thin-section of a specimen from this outcrop (146) confirms that the

porcellanite was derived by silicification of gritty clay similar to that which it

overlies, as the texture of the rock is pseudomorphous after clay, The specimen

is a dense white porcellanite with a splintery fracture, Small grains of quartz

are visible to the naked eye. Under the microscope, the rock consists of a pale

brown siliceous. matte which has no reaction to polarised light. Occasional grains

of detrital quartz present have rounded outlines and show undulose extinction.

Included grains of un-twinned plagioclase, typical of the Precambrian rocks,

are also présent in small quantities,

Although the sediments which have been silicified are Early Miocene in age,

it is considered that the lateritisation occurred in Upper Miocene or Pliocene times,

and the following observations were noted in support of this conclusion:

1, A silicified crust is developed at Pidinga only in the areas where the lime-

stone has been completely denuded by erosion. (An exception does occur

at Ifould’s Lake, four miles north-west of Pidinga, where grey clay and

partially porcellanised gril underlies a yery thin bed of fossiliferous

limestone).

2. No [ragments of porcellanite were observed within the pebbly fossiliferous

limestone, either by the naked eye or in thin-sections. The pebbies consist

only of detritus from the Precambrian rocks,

3. The fossiliferous limestone is itself highly silicified,

4. The “Duri-Crust’ was formed prior to the excavation of the Pidinga lake

systems (Pleistocene), as large boulders uf the formation occasionally litter

their surface.

It is likely, therefore, that the processes responsible took place during the

Pliacene petiod, This is in agreement with findings in other parts of Australia,

for example, Whitehouse (1940) and Crocker (1946) reached a similar conclusion

iollowing studies in Queensland and South Australia respectively,

DIAGRAM

SHOWING

THE GENERAL STRATIGRAPHIC SUCCESSION AT PIDINGA

DESCRIPTION OF STRATA ‘ ANO

ENVIRONMENT

RECENT

Terrestrial

HODLE MIOCENE

Sholew Moring

Porcellanised claystore and grit, surface guarizite efc, Raotiolaria +

Pate yellow and green gypseous quarts sand ond grit Cenozphaera

White friable gypseous clays some selenite crystala (Crespin)

Pale qrey sondy clay patches of ironstone and lerruginous sendstere.

LOWER MIOCENE

Mainly shallow

Winte and vars cofgured otunitic clay facusirine

Lower bedls are

unfasst'Terous

Reo, brown and yellow fine ochreous sond or ochreous sandstone

crust

Yellow, ced and grey mollied clay - sandy

Vari-colovred iran.stained mottled clay

—— F

—— as

————

———s

‘ ——!

aes

— aE

——— se

——

— ae

a |

————

— |

SS_

arene

——

———

——s

Pollen & Spores

of families: OLIGOCENE

Lignilic Series Proteaceae

Myrieceve

Epacridacece

fagacece

(Pike

lacustrine

Corbonacesus clay and sand with fragmenta ef decomposed

wood and pyriles,

i is tC

Grey clay

White and iron-atained grilly aluaitic cloy with fhe ferture DECOMPOSED

of decomposed grers 7 PRE-CAMBRIAN

PRE-CAMBRIAN

Gneissic granite, epi-diorite and amphibolite ete. Metamorphic

Fig. 3

PART II — PETROGRAPHY OF THE PRECAMBRIAN ROCKS

A detailed petrological study of the Precambrian gneisses which are exposed

in the vicinity of the Pidinga Lakes is presented in this section, and reference is

also made to similar occurrences at Ifould’s Lake and Lake Tallacootra. Previous

work has amounted to brief general descriptions of the gneisses by the former

Government Geologist, H. Y, L. Brown (1898) and explorer F, R. George (1905}-

GENERAL CHARACTERS AND CONSTITUTION

The belt of gneisses which outcrops at Pidinga is the largest exposure of the

Precambrian formation in South Australia west of the Gawler Ranges and south

of the Trans-continental Railway, and with the stnaller occurrences at Ifould’s

Lake and Lake Tallacootra, are the most westerly in South Australia south of

the railway line,

The Precambrian rocks protrude at intervals for a distance of approximately

eight miles along a ridge on the western fringe of the Pidinga Lakes, and at

some places on the lakes (pl, III, fig. 1), They consist of an assortment of gneisses

in which the components are transgressional from one to the other or intermingled

im a complex fashion, features which are common to many of the other occurrences

of Precambrian rock in western South Australia. They are considered tentatively

as Archean in age and may be correlated with the similar formations of south-

eastern Eyre Peninsula and lower Yorke Peninsula which are overlain uncon-

formabty by Proterozoic sediments,

The gneisses which occur at Pidinga may be classihed into three major

Zroups -—

1. Older Series of Gueisses—The older gneisses are mainly dioritic in com-

position but also there are highly metamorphosed calcareous and siliceous sedi-

ments, amphibolites and plagioclase hornblende schists, occurring as irregular

intercalations within the dioritic gneisses, A characteristic of this group of

rocks is the presence of abundant dyke-like intrtsions and segregations of pegma-

titic and aplitic appearance and composition.

2. Basic Rocks—Included here are metamorphosed basaltic dyke rocks and

an occurrerice of peridotite, all of which intersect the older series of gneisses,

3. Granitic Augen-Gneisses and Associated Migmatites—This group com-

prises uniform, granitic rocks and related migmatites of younger origin.

The yariety of gneisses recognised have in the majority of cases such complex

inter-relations that it is not possible to map them as separate identities. The

difficulties of interpretation are increased by the discontinuity of outcrops which

has resulted from preferential erosion, The ridge of Precambrian rock probably

owes its prominence to the resistance to weathering of the granitic members

which recur as bold outcrops at intervals throughout the area. The other types

are exposed only where creeks have dissected deeply into the sedimentary coverage,

or as erosion platforms at the surface of the lakes.

The general foliation of the gneisses is reasonably uniform at each of the

outcrops. The strike ranges from 10° E, of N., to 50° E, of N., and the dip is

almost always vertical. Local exceptions are mentioned in the text.

As the outcrops are geographically intermediate between the pold-bearing

Precambrian rocks of Tarcoola (South Australia) and Kalgoorlie (Western

Australia), the area has been thoroughly prospected, but no metalliferous minérals

in any appreciable quantity have ever been reported. A suite of samples. from

Pidinga were assayed for gold by the Mines Department (1933). None were

found to be auriferous. Graphite oceurs disseminated throughout the gneisses

on the western edge af Tfould’s Lake, but in such small quantity as to be of only

academic interest.

A number of specimens representative of the formation as a whole were

submitted to the Geophysical Section of the Mines Department for determination

of radioactivity, The results were “not significant.”

THE GLDER SERIES OF GNEISSES

INTERCALATED SEDIMENTARY GNEISSES

There is evidence that portion of the gneissic terrain originally comprised

rocks of sedimentary character, which were later almost completely digested by

igneous intrusions, or otherwise highly altered by metamorphic and additive

processes.

At Pidinga, there are incorporated in the gneisses on rare occasions some

small remnants of fine-gramed highly siliceous rocks resembling quartzite, and

cale-silicate types, These occurtences are characterised by pseudo-bedding struc-

tures in which the dips ate much flatter than the vertical foliation of the igneous

gneisses.

_ The occurrence of graphite as a disseminated mineral throughout the gneisses

exposed on the western fringe of Ifould’s Lake, four miles north-west of Pidinga,

and the abundance of cordterite in other specimens, are other features which,

although not real criteria, are characteristic of gneisses of sedimentary origin.

Typical of the calc-silicates is a pale greenish-grey fine-grained scapolitised

clinozoisite diopside grassularite rock (52), Free calcite also occurs in abundance,

and the minor constituents are zoisite, epidote, sphene, plagioclase, quattz and

magnetite, The minerals are irregularly distributed and the micro-structure is

granoblastic. The assemblage is characteristic of a regionally metamorphosed

magnesian limestone.

A coarse variety of cale-silicate, 4 garnet epidote calcite rock (33), occurs

as what is apparentiy a xenolith in dioritic gneisses, It is a handsome rock con-

sisting of shapely crystals of reddish garnet and green epidote associated with

pink calcite and some quartz, and varying in grain size from medium to very

coarse. The rock comprises the dump around a small pit situated about one-

quarter mile east of Pidinga Rockhole. The epidote was previously designated

green tourmaline by explorer F. R. George (1905), who discovered and prospected

this interesting occurrence. There are no outcrops in the immediate vicinity of

the pit, but close at hand in all directions the country rock consists of dioritic

gneiss, An unusual and quite porous calcareous capping is the only surface

indication of the occurrence. The pit has fallen in and the specimens lying at

grass consist only of this rock.

Cordierite-bearing rocks are known only from 2 small exposure at the eastern

end of Ifould’s Lake (102), which consists of fine to medium-grained feldspar

yarnet cordierite gneiss, Grey bands rich in feldspar and quartz alternate with

dark bands camposed of biotite, garnet and yellow cordierite, The mineral com-

position is typical of gneisses derived from argillaceous sediments with their high

alumina content.

In thin-section, there is a pronounced foliation of the mineral constituents

and the texture is for the most part granoblastic, with a modification in some places

where shear has effected granulation at the margins of the grains, -The chief

minerals present are microcline microperthite, cordierite, plagioclase, quartz,

biotite and garnet. Clinozoisite and rutile are conspicuous accessory components.

Also present in small quantities are muscovite, titaniferous iron ore, zifcon and

epidote. Another specimen from the same locality (99) is very similar apart from

a higher proportion of potash feldspar relative to plagioclase.

AMPHIBOLITES AND PLaciocLasz Horns cENDE ScHisTs

Amphibolites and plagioclase hornblende schists occur as abundant dis-

continuous masses and schlieren within the complex of older gneisses. A typical

area is shown in pl. III, fig. 3. They resemble in every detail the larger amphi-

bolitic masses observed as inclusions in the gneisses elsewhere in western South

Australia, as for example those of Rocky Point and Cape Thevenard (near

Penong and Ceduna, respectively). In each of these places the amphibolite

appears to represent remnants of former basic igneous (doleritic?) bodies,

emplaced as sills or dykes, or perhaps surface flows, prior to the regional meta-

morphism and related processes which were responsibie for their partial oblitera-

tion and alteration. It seems likely that they are all related to one and the same

period of basic intrusion, or eruption.

Rocks of this group are fine-grained and usually schistose. The mineral

asseinblage of each is very similar, the dominant constituents being plagioclase,

hornblende and quartz. Biotite is usually more abundant than accessory and has

apparent'y formed to some extent at the expense of hornblende, asa retrograde

effect. Epidote, iron ore and sphene are accessory minerals, Minor quantities

of relict brown hornblende occur as small grains in two of the sections prepared.

The approximate modes are shown in Table [. The varieties designated as plagio-

clase hornblende schists differ only in a higher content of plagioclase,

TasLe I

Approximate Modes of Amphibolites and Plagioclase Hornblende Schists

ROCK No. 106 124 {21 109.

Plagioclase Plagioclase Plagioclase

Napie Hornblende Hornblende Amphibolite Hornblende

Schist Schist Schist

Plagioclase - - - - 50 50 10 50

and

Composition - - - ~ Ab70 Ab70 Ab70)

Quartz - - - - - - 20 20 10 20

Hornblende - - - + 15 15 70 25

Biotite ~ - - - - - 10 10 10 acc.

Epidote - - - - - ace, acc. acc.

Tron Ore - - - - - ace, acc. acc.

Sphene - - - - - - acc, acc, acc. acc.

One of these rocks (121) is a fine-grained amphibolite of dark grey colour.

In section, well-developed individuals of hornblende form an interlocking mesh-

work of radially orientated prisms, and small plagioclase and quartz grains occupy

interstices, Shearing stress has slightly modified the texture, as small flakes of

biotite which appear to have heen developed from hornblende as a result of stress

_ have a strict parallel arrangement in contrast to the hornblende. Sphene is

accessory.

Dtoritic GNEISSES

Dioritic gneisses. are important components of the gneissic complex at

Pidinga. They occur extensively and, apart from the presence of enclosed

schlieric remnants of finer grained amphibolites and plagioclase hornblende

schists, they are reasonably uniform in both constitution and general field

appearance,

The mineralogical characteristics of the group are the abundance of plagio-

clase and quartz, with biotite and/or hornblende as the mafic constituents. Modes

are shown in Tables II and IJ£. The quartz and plagioclase normally form 3

granoblastic mosaic with indistinct boundaries to individual grains, but occasionally

the plagioclase is lath-shaped. The parallel arrangement of such elongated

feldspar crystals and the mafic minerals are responsible for a gneissic structure,

In some varieties, foliation of plagioclase and hornblende is very marked. Super-

imposed effects of dynamic metamorphism have caused partial granulation of the

mineral assemblage in a number of these rocks.

TasLe II

Approximate Modes of Hornblendic Dioritic Gneisses

-- Oo

ROCK Noe. 148 2 93 118

Banded Lineated Banded Banded

Name Dioritic Dioritic Dioritic Dioritic

Gneiss Gneiss Gneiss Gneiss

Plagioclase - - - - 55 50- 65 40

and

Composition - - - = Ab65 Ab60 Ab75

Quartz - - - - - - 15 5 acc. acc,

Hornblende - - - = 15 25 30 45

Biotite - - - - - = 15 10 acc. ace,

Epidote - - - - - acc. acc,

Iron Ore - - = - - acc. acc. ace. 5

Sphene - - - - - - acc. acc,

Tasie III

Approximate Modes of Biotitic Dioritic Gneisses

ROCK No, 1 112 108 92 22

Dioritic Dioritic riety wie red

Dioritic Dioritic Dioritic

ane ear ari Gneiss Gneiss Gneiss

Plagioclase - - - - 40 65 50 65 70

and

Composition - - - ~- <Ab7Q Ab75 Ab65 Ab70

Potash feldspar - - - acc.

Quartz - + = + - - 35 10 35 20 20

Hornblende - = - -

Biotite - - - += - - 20 20 10 10

acc, acc. 10 5 acc.

Tron Oré - - - - - acc. acc. acc, acc, ace,

Sphene - - - = = - ace. acc.

The plagioclase is consistently of a composition near Ab,,. Twinning is often

vague or absent. Other properties are a patchy distribution of saussuritic altera-

tion and, more rarely, a zonary extinction.

Biotite, or chlorite pseudomorphous after biotite, is the ustial ferro-magnesian

constituent of the fine-medium grained types, whereas hornblende is chiefly

developed in the coarser varieties, The latter occur in proximity to granitic

masses discussed later (see page 39) and are apparently a more highly meta-

morphosed facies of the biotite-bearing gneisses. The replacement of biotite by

hornblende can be observed in thin section, and the nature of the change is illus-

trated by the modes. Hornblende takes the place of biotite plus quartz, and the

plagioclase becomes a slightly more basic variety, Epidote occurs in minor

amounts as an associate of biotite and can be seen to be forming at the expense of

the degradation of that mineral to chlorite and iron ore. Sphene is a common

accessory of the hornblendic rocks and was probably a released mineral during

the conversion of biotite to hornblende, Ilmenite, pyrites, apatite and zircon are

other accessory minerals,

Thus it is considered that the variety of rock types within the group of

dioritic gneisses is determined largely by the stage of metamorphism to which

they have been subjected, In brief, the dominant types are:

granulated plagioclase quarts biotite gnetss;

plagioclase quarts biotite augen-gneiss;

lingated plagioclase hornblende biotite gneiss;

banded plagioclase hornblende biotite gnetss.

The dioritie gneisses occur in close association with amphibolites and plagio-

clase hornblende schists of remarkably similar mineral composition {see Tables I,

I] and III), and these types grade imperceptably fromm one to the other and are,

no doubt, genetically related. They all appear to have been derived by various

stages of metamorphism of igneous rocks, mainly doleritic, or by metamorphism

of a series of dolerites and diorites related to the one magma. The gradation of

amphibolite to dioritic gneiss observed at Pidinga is also a pronounced tmeta-

morphic feature of the same seriés of Precambrian rocks which form an extensive

coastal shelf at Rocky Point,

Good exposures of the diorilic gtieisses occur in the bed of a small lagoon

neat Pidinga Rockhole, A specimen from this locality (2) is @ lineated plagio-

clase korublende biotite gneiss of medium grain and dark colour. The elongated

minerals have a common orientation, giving rise to a pronounced lineation.

The thin-section reveals a rigid parallel arrangement of the mineral assem~-

blage, The plagioclase (Ab,, An,jq)is the dominant constituent and forms a

matrix of elongated laths in which are embedded hornblende and biotite, Quartz

is a minor constituent. The hornhlende is present as sub-idioblastic crystals with

humerous inclusions of iron ore, Colummar crystals and granular aggregates of

clinozoisite are preserit in small quantity in association with the biotite,

A dioritic gneiss also comprises portion of a small outcrop at the castern

end of Ifould’s Lake (100) and is similar in many of the microscopic features

to those of Pidinga. In addition to the normal components of the dioritic

gneisses, however, skeletal crystals of garnet, and xenoblastic clinozoisite derived

by the alteration of plagioclase, are also important constituents, and rutile is a

common accessory mineral, .

FiAser PLactoctase Quartz Dyke Rocks

Several acres of uniform white flaser tock consisting of mediym-grained

plagioclase and quartz are exposed on the southern portion of the small lake at

Pidinga designated Lake C, The contact with the surrounding rocks is hidden

hy lake deposits.

Microscopically, this rock (145) is a medium to coarse-gratned lencocratic

plagioclase quartz augen-gneiss, The section is composed essentially of plagio-

clase augen with attrited margins set in a finely gramulated and orientated matrix

of plagioclase and qtiartz, The plagioclase is of composition Ab;) Ang,. Also

present is one porphyroblast of clear microcline and occasional small irregular

grains of micrographic microperthite. Sericite and muscovite have developed

along cracks in the feldspar as a result of shear, Quartz is foliated into lenticular

masses with mosaic structure.

Another specimen fram the same occurrence (7) has been considerably

modified in composition by later introduction of potash feldspar.

Identical rocks occur in many places at Lake Tallacootra as narrow dykes

Which have been patticulatly resistant to erosion to form discontinuous wall-like

uutcrops, but their relation to the other gneisses is again obscured by a super-

ficial coverage.

ApLitic VEINS AND SEGREGATIONS

A feature of the older series of gneis¢es is the abundance of dykes of quartz

aud feldspar-quartz pegmatites, and irregular segregations of aplitic or pegmatitic

material. They vary considerably in composition and appearance throughout the

area generally, and no attempt has been made to distinguish them as related to

one or another parent type. Thin-sections have been prepared of two of the

finer-grained varieties.

A section of a medium-grained pink gneissic aplite (15) shows that the slight

tendency towards foliation is effected by the parallel arrangement of the small

amount of biotite present and occasional lenticular quartz aggregates in an other-

wise non-directional mosaic of equi-granular plagioclase, potash feldspar and

quartz. Effects of dynamic metamorphism are illustrated locally by areas of

crushed grains wedged between more resistant crystals, giving rise to a mortar

structure. The potash feldspar is perthitic on the borders of most grains.

Accessory are iton ore, seticite and muscovite. An idioblastic monoclinic yellow-

brown mineral included in the plagioclase has the properties of orthite.

Another varicty is a flaser granite aplite (4). It is a very fine-grained dense

felsic rock which has suffered extreme shear.

The whole of the rock has been reduced to a fine-grained aggregate of mainly

microcline and quartz, with subordinate plagioclase (Ab,,An,,) and biotite,

showing mortar structure. A few miicrocline grains that have withstood the

shattering effects beyond being reduced to lenticular rerinants are of slightly

larger dimensions. The individuals of the assemblage show elongation in the

direction of movement. Quartz, in particular, occupies long discontinuous bands

and lenses. Iron ore is accessory,

Baste Rocks

In a few localities where the country rock is otherwise composed of 4

diversity of dioritic gneisses and amphibolites, there are some cross-cutting narrow

dykes of dense basic to ultrabasic rock, with sharp contacts, which can be traced

as such for as far as the exposures permit. These are of younger origin than the

complex of gneisses, Specimens of two of these dykes were sectioned. Both

showed metamorphic effects, including the development of prehnite and antho-

phyllite respectively. The latter rock is apparently a metamorphosed pyroxenite,

Included in this section is the occurrence of peridotite rock which also

appears to bear an intrusive relation to the dioritic gneisses, etc. This ultrabasic

rock forms a bold isolated outcrop, elongated and covering an area of about hale

an acre. There are several highly basic dykes similar to those described in the

preceding paragraph in this vicinity and it seems likely that they are related

genetically to this plutonic rock. The metallic appearance of the pyroxene

constituent of the peridotite hag evidently attracted the attention of prospectors

as the outcrop is enclosed by lease pegs.

Prehnitised dolerite dyke—a dense greyish-black rock of extremely fine

grain (129).

In thin section, a palimsest ophitic texture is still in evidence and shearing

effects are absent. Conspicuous tabular phenocrysts of prehnite, pseudomorphous

after plagioclase feldspar, occur at random in a microcrystalline groundmass

composed uf a matte of abundant plagioclase, chlorite, prehnite, iron ore and

quartz. Staining due to limonite obsctires portion of the slide,

Piagtoclase anthophyllite quarts dyke rock—This (105) is a fine-grained

dense greenish-grey dyke rock of high specific pravity in which fone of the con-

stituent minerals can be determined in the hand specimen.

Microscopically, the texture is controlled by abundant crystals of the colour-

less amphibole anthophyllite comprising a mesh-work of interlocking prismatic

erystals and columnar aggregates and set in a fine-grained matrix of plagioclase

and quartz, The plagioclase includes some anthophyllite and is a basic oligoclase

with poorly defined twins. The minor amount of quartz is present as very small

blebs. The anthophyllite is studded with numerous minute inclusions, Rutile

is accessory.

Diallage olivine peridotite rock — A. specimen (56) in which pyroxene with

a metalloidal lustre on the weathered surfaces can be scen to be the chief con-

stituent. Brown biotite is visible in the hand specimen but absent in the slide.

There are no obvious effects of metamorphism.

A thin-section study reveals that the rock consists of the pyroxene diallage,

olivine and brown hornblende, and the texture is holocrystalline hypidiomorphic

granular, modified by the occasional development of diallage phenocrysts,

Diallage is the dominant component of the assemblage. Brown hornblende occurs

as an overgrowth on the diallage and has evidently formed at its expense. Plazio-

clase is present in subordinate amounts (about 5%), Twinning is not sharp but

the wide twin laminae are typical of basic plagioclase, Olivine is represented by

colourless anhedra with polygonal outlines, It is altered to serpentine on the

margins and along fractures.

Tue Granitic AUGEN-GNEISSES AND AssocIaTED MicMATITES

The red granitic augen-gneisses are among the more common of the types

constituting the Precambrian outcrops at Pidinga. They occur at intervals as

elongated or lenticular masses which vary from just a few yards to more than

half a mile in longer dimensions. The appearance is uniform in each of the many

outcrops, in contrast with the heterogencous nature of the types already described

as components of the surrounding mixed gneisses. The outcrops are often of a

bold nature, as they have resisted weathering to a greater extent than the other

members of the Precambrian basement (pl. III, fig. 2}. A typical example is the

several acres of rock exposed at Pidinga Rockhole.

The granitic gneisses are younger than the mixed gneisses which they replace,

but their relation to the basic dyke rocks is not evident, Their elongation corre-

sponds with the general gneissosity of the complex as a whole, and they are thus

considered to have been emplaced during a period of regional metamorphism of

which there is evidence throughout the area, and certain features are presented

which suggest that metasomatic processes were responsible fot their formation.

A major consideration in the study of genetics of the granitic gneisses is the

occurrence of partially feldspathised dioritie gneisses and amphibolites in

proximity to their margins, and rocks of this category are also described in this

section, The widespread pegmatisation of the older mixed gneisses (see p. 38)

may have taken place at the same time and in a similar way but such 4 relation-

ship cannot be confirmed due to the discontinuous nature of the exposures,

PeTnocRAPHIC CHARACTERS oF THE GRANITIC AUGEN-GNEISSES

A petrographic study of the granitic augen-gneisses confirms that the mineral

assemblage and siructure of the rocks from separate outcrops are reasotiably

constant.

The essential constituents in order of abundance are potash feldspar, quartz,

plagioclase and biotite. The plagioclase is of composition intermediate between

oligoclase and andesine, Epidote, iron ore, sphene, tourmaline, apatite and zireon

are accessory minerals. Garnet is another minor constituent but is not represented

in the thin-sections prepared from these rocks, The modes of typical specimens

are shown fn Table IV.

Taste IV

Approximate Modes of Granitic Augen-Gneisses

ROCK No. 104 10 31 32

Name Atigen- Augen- Augen- Augem-

gneiss gneiss gneiss gneiss

Plagioclase - - - - 10 25 ace. 3

and

Composition - - ~ ~ Ab7Q AbzO

Potash feldspar - - - 45 40 60 60

Quartz - - - - + - 35 25 30 30

Biotite - - - - - = 5 5 5 §

Epidote - - - - - ace. 3 acc, ace,

Iron Ore - - += - = ace. acc,

Sphene - - - - = - acc.

The augen structure is controlled by lenticular porphyroblasts of feldspar,

dominantly orthoclase and to a lesser extent microcline or plagioclase, arranged

parallel in a finely granulated matrix. There is evidence that the stress effects

promoted the conversion of orthoclase to microcline, and in other cases, perthite.

The effects of the superimposed dynamic metamorphism have almost completely

destroyed the former texture, but occasionally areas preserved from crushing

show granoblastic relations with indistinct crystal boundaries,

A section of one rock (104) shows unusual relations of the plagioclase atid

potash feldspar. In one instance, where a large porphyrcblast of microcline

adjoins a crystal of plagioclase, the margin of the latter has been cleared of

inclusions and is in optical continuity with the potash feldspar, although the R.I.

is still greater than that of the microcline. The remaining portion of the plagio-

clase grain contains a micrographic intergrowth of potash feldspar. Another

relic grain of corroded and sausstiritised plagioclase is rimmed completely with

clear microcline. Elsewhere, rounded blebs of clear potash feldspar are common

throughout the dusty plagioclase.

The potash feldspar is quite fresh and clear in comparison to the highly

dusted and partially saussuritised plagioclase, and the large porphyroblasts are

often surrounded by irregular blebs of perthite and anti-perthite. They carry

occasional large inclusions of biotite, epidote and quartz arranged parallel to the

gneissosity, A majority show vague cross-hatching,

Tourmaline is present in the section of rock (32) where it occurs as small

idiobiasts pleochroic from pale yellow to dark green-black. ‘The crystals have

a random orientation in an otherwise rigidly gneissic environment suggesting a

late stage introduction of that mineral.

FELDSPATHISATION PHENOMENA

Field observations combined with petrological studies reveal features which

suggest that the granitic gneisses may owe their origin to metasomatic replacement

(chiefly feldspathisation) of pre-existing dioritic gneisses and amphibolites, ete.,

rather than normal igneous intrusion. Phenomena which are considered to demon-

strate metasomatism are outlined below :—

1, The contacts of the granitic gneiss with the dioritic gneiss and othet

rock types of the metamorphic complex are often of a vague transitional nature,

In the exposures east of the Pidinga Shed Tanks and near Pidinga Rockhole, the

margins of the granitic gneiss are intermingled in a lit par lit fashion (pl. III,

fig. 4) with the adjacent dioritic gneisses to form rocks of a truly migmatitic

charactet, In other instances, where the change from one type to the other appears

abrupt to the unaided eye, a thin-section study shows that potash feldspar has

nevertheless been introduced interstitially for considerable distances beyond the

boundaries of the granitic gneiss, The gradation from dioritic gneiss through

migmatites to granitic gneiss is illustrated in Table V. Rocks No, 24, 23 and 22

were collected as a series (see geological plan) at regular distances (10, 20 and 30

yards respectively) from the contact of the granitic gneiss near the Pidinga Shed

Tanks, Thin-sections of rocks of migmatitic character, the modes of which are

included in Table V, are described in the following section.

TABLE V

Partial Modes of Rocks Gradational from Dioritic Gneiss to Granitic Gneiss

Plagioclase Potash

Rock No. Name and feldspar Quartz Biotite

Composition

22 Dioritic 70 _— 20. 10

Gneiss - - - - += - <Ab70

1 Dioritic 40 acc, 35 20

Augen-gneiss - - = <Ab7Q

23 Partially Felds-

pathised 65 10 10 10

Dioritic Gneiss - - - Ab70

24 Partially Felds-

pathised 45 20 25 5

Dioritic Gneiss - - - Ab70

29 Highly Felds-

pathised 20 40 30 5

Dioritic Gneiss - - = Ab70

Granitic 10 45 35 5

104 Augen-gneiss - - - Ab70

2. The plagigclase which is constantly present as a constituent of the

granitic gneisses is identical in general microscopic appearance, form (lath-shaped

where preserved from granulation) and composition (Ab,, An,,) to that which

characterises the older dioritic gneisses and amphibolites. It is usually repre-

sented by corroded relicts or aggregates.

3. The potash feldspar is quite fresh and free from impurities in com-

parison to the plagioclase, which is dusted with minute inclusions and products

of incipient saussuritisation,

4. Possible stages in the replacement of the plagioclase by potash feldspar

ne Peraee in one specimen of the granitic gneiss (104) and have already been

escribed.

DescrivTION OF MIGMATITES

The rocks described hereunder are partially feldspathised rocks (chiefly

dioritic gneisses) collected from neat the contacts with the granitic gneisses.

Partial modes of several of the thin-sections described are shown in Table V.-

Partially feldspathised dioritic gneiss (24) —Medium-grained dark bands

rich in clear plagioclase, biotite and quartz grade into pink coarser-grained granitic

hands.

The gneissic structure is imparted by parallel orientated biotite flakes, in an

otherwise xenomorphic inequigranular matrix of rounded feldspar and quartz

gtains. This hag heen modified by shear, resulting in the comminution of crystal

boundaries against one another, and cracks through individual ‘crystals.

Both plagioclase and potash feldspar are essential constituents, but the latter

is restricted to narrow bands with quartz which pass gradationally inta the main

mass of the rock, where plagioclase is the dominant feldspar, The plagioclase

is usually untwinned. It is of composition Ab,, An,,. The potash feldspar is

mainly microcline but thete are also patches of a xenomorphic perthite mosaic.

The microcline is quite clear in contrast to the plagiotlase which carries segrega-

tions of impurities, Quartz is abundant throughout the slide, Chloritised biotite

and sub-idioblastic epidote are essential constituents of the plagioclase-rich areas.

Muscovite, iron ore, zircon and apatite are accessory.

In another specimen (23) the introduced potash feldspar is restricted to

small isolated lenticular zones.

The bulk of the rock consists of medium-grained colourless plagioclase,

biotite and quartz. There are lighter-coloured discontinuous bands ofl clots rich

in pink potash feldspar, with a sharp demarcation at the margins in the hand-

specimen.

The textttte is controlled by the predominant mineral, plagioclase Ab,, Anz,,

which forms a granoblastic aggregate of rounded grains with a tendency towards

directional orientation parallel to the gneissosity. Biotite flakes have a rigid

parallel alignment and quartz is segregated into lenticular mosaics,

The mineral assemblage varies in some local elongated clots, where micro-

cline is the predominant feldspar and carries aggregates of sphene. The texture

and structure are nevertheless constant throughout, having been impressed by

dynamic stresses which resulted itt the shattering and granulation of the mineral

colstituents, These effects have been in part healed by local recrystallisation.

The plagioclase is studded with abundant small inclusions. Twinning is

indistinct or absent. Lines of inclusions parallel the twin planes or former twin

planes. The microcline is quite clear with poorly defined gridiron structure,

Biotite occurs as small xencblasts in an advanced stage of alteration to green

chlorite, Epidote is present in quantity as xenoblastic aggregates or ptismatic

subidioblasts of moderate dimensions, often associated with and including

ehloritised biotite. Large yellow-brown sphene grains are only slightly pleochroic.

Occasional rounded grains of calcite are interstitial amongst the plagioclase

or included in it. Other accessory minerals are apatite, iron ore, muscovite and

zircon,

ACKNOWLEDGMENTS

The writer is highly indebted to Mr. S. B. Dickinson, Government Geo-

logist of South Australia, for providing an opportunity to carry out the field

work and making available facilities of the Mines Department, as well as

most helpful criticisms and suggested research during preparation of the

manuscript. He also wishes to thank Professor Mawson and other friends and

colleagues who contributed advice, and for technical assistance by Miss I. Crespin

(Commonwealth Palaeontologist) and Mr. B, C. Cotton, Conchologist at the

Adelaide Museum.

‘QUOISSUTIT SNOA{ISSOT ae punossyoeg ‘ONRTT BAuIpig Urey AY} JO uONsod ssordE MaLA

ayy Wl SHY MOT AY], “OyRT Bsurprg wleyY ayy jo ¢ Sty

APUWAIIXA W]saM-ypNOS ayy, Je Uowseadap pasoquiry "7

p Sty

Vol, 74, Plate IT

“2I]U9D BY} UE dosQyNO SsYIOL UBUQUILIIAT

QYRT EOOIRYET UlRpY ayy Ssosoe vuIEIOUR

@ ‘Sy

‘QUOISIWIL SNOJAT [ISSO]

Sf YOY “SKY EFupg wey sy) uo ,purysy,,

1 “314

Trans. Roy. Soc. S. Aust., 1950

Vol. 74, Plate III

Trans, Roy. Soc. S. Aust., 1950

‘aOYNIOW ESUIlplg Jvau ssisus Iy1Wo0—p pure ‘esulpig ‘SsuD jo

SSIUS-UIdNY DUEIS JO asnjonays Jy aed WY as1e07 Ajrxajdmos & ul ayyoqiydure yo sxeasyg

Fla e “BIy

: iy S ss :

_ . ‘

‘QOUsIOYW BSuiprgq ‘DJOYYIOY Vsuipig svau woosr[ eB yo aspa ayy

deau Surddossyno ssiaus duels URLIquUEeIg uo Siiddossjno sassia@usd DIOP URLiquinsasg

zZ Sly T Bly

— LEGEND —

RECENT

AMODLE MIOCENE

foss(iiferous silvcitied gritty hmestone efc__ . ~~~

LOWER MIOCENE

Porcellanised claystone and grt, surface guartzite____

Fercugineus sandstone and ochreous crusts, _

Vacenselidated grit, sand and vari coloured clay and atarisve.

CLIGOCENE

Ligaitic series- only prover) aréas where less than St helen

Sucface of lake shown on plan

PRE-CAMBRIAN

Red granitic augen-gaerss_____.

Comptes of mised gneisses ~ mainly or

REFERENCE TO SIGNS

Geolegical boundaries

VP OCR Bet aA oe Fos ae ee eee cee So Eat SoS Ss 3 ee —

Grerssesity

Chffs e

locetion of specimens mentioned m feat. ~~ — ~~~ ~~~ -~-~—---- a

Geological sections described in tert _______ ____ ---~-~--—--~-----= Section 41

West Lowe

—A

Track te, Coldea _ _ Section WEF

of sections

~~" 3

neces ‘ _

: (gee AH

ae me

Track

¥ Pidinga Shed Tanks

Trial well

“Section WISE:

PIDINGA AREA

GEOLOGICAL PLAN & SECTIONS

“— SCALE —

Maia Pidinga Lake

Main Piainga Lake

LIST OF REFERENCES

Tate, R. 1878 The Natural History of the Country around the Head of the

Great Australian Bight. Report of the Philosophical Society of South

Australia, 1879-79

Jones, J. W. 1880 Examination of the Country North-East of Eucla, Parlia-

mentary Paper No. 191

Brown, H. Y. L. 1885 Report on the Geological Character of the Country

passed over from Port Augusta to Eucla. Parliamentary Paper No, 45

Gites, Ernest 1889 “Australia Twice Traversed,” 2

Brown, H. Y. L. 1898 Government Geologist’s, Report on Explorations in

Western Part of South Australia, Parliamentary Paper No. 46

Grorce, F. R, 1905 Report of Mr. F. R. George on his Prospecting Expedition

North of the Nullarbor Plains. Parliamentary Paper

1908 General Notes, Pidinga Lignite. Recotd of Mines of South Australia

Ginn, Marttanp A., 1919 A Summary of the Geology of Western. Australia.

Memoir No. 1, Geological Survey of W. Aust.

Warp, L. K. 1926 Pidinga Lignite. Mining Review No. 44, Department of

Mines of South Australia

Warp, L. K. 1932 Pidinga Lignite, Mining Review No. 57, Department of

Mines of South Australia

Warp, L. K. 1939 The Occurrence of Lignitic Matter Neat Malbooma.

Mining Review No. 71, Department of Mines of South Australia

WuureHouse, F. W. 1949 Studies in the Late Geological History of Queens-

land, University of Queensland Papers, Depattment of Geology, 2,

(new series), No. 1 .

Crespin, Miss I. 1945 Note on the Age and Palacogeography of Brown Coal

Deposits of Gippsland, Victoria, Proceedings of the Royal Society of

Victoria, 57, (new series), 1-2

Crocker, R. L. 1946 Post-Miocene Climatic and Geologic History and its Sig-

nificance in Relation to the Genesis of the Major Soil Types of South

Australia. Bulletin No. 193, C.S.LR., Aust.

Dicxinson, S. B. 1947 Shallow Lignite Occurrence at Pidinga, Mining Re-

view No. 87, Department of Mines of South Australia

1948 General Notes Discovery of Alunite near Ooldea. Mining Review

No. 88, Department of Mines of South Australia

Pree, Miss K, M. 1948 Pollen Investigations on the Ligneous Beds, Lake

Pidinga Bore. Mining Review No. 90, Department of Mines of South

Australia

Armstronc, A. T, 1948 Pidinga Alunite Deposit. Mining Review No, 89,

Department of Mines of South Australia

Kine, D. 1949 A Geological Report on the Nullarbor Cavernous Limestone.

Trans. Roy. Soc, S. Aust., 73

Cresrin, Miss I. 1949 Micropalaeontological Examination of Rock Samples

from Pidinga, South Australia. Report No. 1949/93, Palaeontology

Section, Commonwealth Governm7nt Bureau of Mineral Resources —

unpublished H

AN OCCURRENCE OF CROCIDOLITE NEAR ROBERTSTOWN, SOUTH

AUSTRALIA

BY A. P. WYMOND AND R. B. WILSON

Summary

This paper discusses the petrology and mineralogy of some crocidolite deposits near Robertstown,

South Australia. The crocidolite is associated with dolerites which have been intruded into the

Beaumont Dolomites of the Adelaide System. Analysis shows the mineral to be richer in magnesis

than normal riebeckite.

“

AN OCCURRENCE OF CROCIDOLITE NEAR ROBERTSTOWN,

SOUTH AUSTRALIA

By A. P. Wymonp and R. B. Wriison*

[Read 12 October 1950]

SUMMARY

This paper discusses the petrology and mineralogy of some crocidolite

deposits near Robertstown, South Australia. The crocidolite is associated with

dolerites which have been intruded into the Beaumont Dolomites of the Adelaide

System. Analysis shows the mineral to be richer in magnesia than normal

riebeckite,

I. INTRODUCTION

The occurrence of crocidolite asbestos in the Robertstown area has been

known for many years, and the mining of this mineral has taken place in

several localities. Reports of the mines opened up in sections 2, 2A, and

3A of the Hundred of Bright are given in Mining Reviews of the South

Austrahan Department of Mines, and a list of these is included in the Bib-

liography.

The deposits which have been investigated in this instance, occur in

Sections. 30, Hd. of Bright, 295, Hd. of Apoinga, and 26, Hd. of Bright

(Nos, 1, 2 and 3 Asbestos localities respectively) all of which le between

4 and 8 miles north of Robertstown.

The present investigations were assisted by a Commonwealth Research

Grant, the petrology being carried out by one of us (R. B, W.) and the

mintralogy and drafting of the paper by the other (A.P.W.).

Il. GEOLOGICAL SETTING OF CROCIDOLITE DEPOSITS

The crocidolite occurs in association with meta-dolerites which have

intruded Beaumont Dolomites. The Adelaide System beds in this area have

been simply folded, forming a series of broad anticlines and synclines with

north-south axes. .

The strtictural control influencing the intrusion ‘of the dolerite is an

extensive strike fault, a southerly extension of the Kooringa Fault of the

Burra area (1), Severe crushing and brecciation is evident adjacent to this

fault zone, ;

Ill. CROCIDOLITE HOST ROCKS

(a) Meta-dolerites

What may have originally been doleritic intrusions have been altered,

probably by late magmatic action, to albite-biotite types, here termed “meta-

dolerites.” Rocks of this group differ widely in appearance, but in surface

outcrop are all soft and friable. The persistent occurrence of albite and

green biotite is their most common feature,

They have the characteristic dolerite texture produced by inter-locking

feldspar laths (8788, 8788A, 8789). The feldspar is always albite (Ab96),

and varies greatly in size in two (8/788, 8788A), being present as pheno-

crysts up to Siam. long. The albite laths are crowded with fine inclusions

of green mica, sericitic mica and tron oxides, Green biotite often occurs

as decussate aggregates up to 4mm. in diameter. The amount of this bio-

tite is very variable in the different rocks, being so abundant in some (8792)

that the texture may be more aptly described as hornfelsic, though a relict

doleritic texture may be seen.

* Geology Department, University of Adelaide.

Trans. Roy Soc, S, Aust., 74, (1), March 1951

In the groundmass, green biotite and small feldspar iaths are abundant,

while ilmenite, rutile, occasional apatite and secondary calcite are accessory.

There are some vesicular types (8793) with vesicles up to 4mm. in dia-

meter filled with calcite and pink microcline (the calcite forming the core),

and all set in a fine-grained holocrystallinec groundmass. A few albite

phenocrysts are also present.

Crocidolite is not common, being found only in one (8792) as small

fibrous masses, intimately associated with the feldspar.

(b) Tourmalinized rocks

Tourmalinized meta-dolerites are associated with the normal type in

several places, the amounts of tourmaline being very variable (8794-8795).

A poorly defined relict doleritic texture persists in these, The tourmaline

occurs as large skeletal crystals with inclusions of albite, which often have

similar optical orientation, suggesting replacement of feldspar by tourma-

line. Albite (Ab94) is present as irregular laths with some interlocking tex-

ture. What appears to be talc is abundant as small colourless plates, and

biotite, crocidolite, ilmenite and rutile are also present.

Vesicular meta-dolerites have also heen tourmalinized. Some of the

vesicles are filled with microcline (8795— c.f. 8793 above) while in others

(8790) the vesicles, up to 5mm. in diameter, are occupied by calcite and

chalcedony, ad are set in a fine-grained matrix consisting essentially of

tourmaline showing decussate structure; rutile, biotite, albite and apatite

being accessory,

All these rocks appear to be meta-dolerites which have undergone vary-

ing degrees of tourmalinization.

At another locality (No. 3) crocidolite is found in a zone of crushed

dolomite marble. The host rocks are crocidolite-talc-albite marbles (8797

and 8798) which are light coloured coarse-grained rocks, and contain abun-

dant blue prisms of crocidolite and white albite (Ab92) crystals, set in 2

matrix of dolomite. The fibrous aggregates of cracidolite are in some places

intergrown with talc. Rutile and apatite are accessory.

IV. OCCURRENCE OF CROCIDOLITE

Small occurrences of crocidolite are widely scattered throughout a large

area, but only three were examined in detail.

At the No. 1 locality, crocidolite was found as small veins, or jatger

imagses, cutting meta-dolerite, also associated with a vesicular tourmaline

rock (8790). Costeens have been dug in several places, but due to generally

poor exposures, the field relations of the various rock types could pot be

determined.

At No. 2 locality (2), a small quarry has been opened up to work the

asbestos, which here occurs as a large number of veins up to 4 inches wide,

cutting meta-dolerite. Patches rich in tourmaline are prominent,

The occurrence at No. 3 locality was slightly different, Here, dolomite

carrying crocidolite was found in a zone about 30 yards wide within an area

of intensely crushed marble.

The mineral occuts. in two different forms; as relatively large masses (up

to 2 or 3 feet across) of short interlocking fibres, and in relatively thin

veins (up to 4 inches) containing both cross and slip fibre. The more mas-

sive vatiety, which predominates at No. 1 locality does not readily break

into fibres, but on crushing, its fibrous nature becomes evident. Much of

this material contains rhomb-shaped crystals of ferroan dolomite. The

crocidolite is a dark blue colour with a silky lustre. Thin sections show

three prominent directions of fibres, intersecting at approximately 60°, pro-

ducing a triangular intergrowth pattern. In the small triangular spaces

thus produced, basal sections of the typical amphibole shape often occur,

The fibrous variety came from No. 2 locality and is of commercial im-

portance, Some physical properties of similar material from the Hundred

of Bright have been published by the Mines Department of South Australia

(3 and 4):

V. OPTICAL PROPERTIES

The optical properties of the massiye and fibrous varieties are set out

below. Slight differences between the two varieties may be noted with

respect to Extinction Angle and Refractive Index.

Colour: Light Blue, strongly pleochroic; X = light sky blue, Y =

yellow to greenish yellow, Z = violet.

Birefringence: Weak to moderate, Max. approximately -014, masked by

high absorption,

Orientation: Length fast.

Interference Figure: Biaxial negative, 2V, approximately 40°.

Extinction Angle: (a) massive form X’A 110 variable to 15°.

Basal Sections symmetrical,

(b) Fibrous; X A C=0°-5°

Refractive Index: (a) massive: a = 1:6652 + -0005

y = 1°6775 + -0005

(b) fibrous; a = 1°6682 + -0005

y = 1:6820 + -0005

In each case the value for a must be considered the most accurate.

Owing to the fibrous nature of the mineral, no value for 8 could be

determined. (Observations were made using the thermal variation

method under sodium light).

Although there are some slight differences, the two varieties may be con-

sidered as essentially the same material.

The mineral may be concltided to be a mixture of the glaucophane and

riebeckite molecules, although it is not possible from the optical data ayail-

able to determine the proportions in which the two molecules are present.

VI. CHEMICAL COMPOSITION

A sample of pure long fibre asbestos from No, 2 locality was analysed

with the results shown in table I (1). For comparison, analyses of Western

Australian and of another South Australian occurrence are shown.

Tape I

I II III

Sid, sort whe . 94°87 53°48 51-94

BUD. ere tee 5°32 0°24

Ti0, As —_ a. 0°68 — 0-01

Fe,0, — .... leds . 16°41 15-16 18°93

Fed wr Feel a. 5°38 3°44 15-25

Mg0 . tne w. 11°34 10:90 3°94

Cad oa wa 0°45 0°72 0°40

Na,0 es ete _. G77 6°30 6°00

K,0 ads om ws O°25 0-70 0°26

H,0+ _.... woes --. 1°62 2°32 2°67

HO- ... as .. O51 0°72 0:72

MnO psp mn -. Tr present 0-01

C0, ran 7 nil 0-22 nil

100-06 99-28 100°37

I. Long fibre crocidolite, 4 miles N. of Robertstown (No. 2 locality):

Analyst, A. P, Wymond.

II, Crocidolite, 9 miles north-east of Robertstown: Analyst, W. S. Chap-

man (5).

III. “Crocidolite Proper” from 8 miles south-east of Willi Wolli Springs,

Hammersley Range, W.A. Analyst, J, N. Grace (7).

In Table IT. the Structural Formula of the crocidolite (Table I. (1) ) has

been calculated.

Tasre IT

Metal Atoms Metal Groups

Sid, woe ee | 487 7.86 8-00

Al,0O, .... - 1:78 0-30 oe

TiO, wee = 068 0:07

FeO, .. -- 16°41 1:76 1-99

FeO tat a. 9°38 0-65

MgQ ... ... 11°34 2°43 3-48

Ca0 shee a woes 0-07

Na0. au aw «= G77 1:89 1-99

K,0 song a 0°25 0-03

H,O+ 2.200 2. 1°62 1°56 1°56

H,0- ... 1. O51

MnO fate mas Tr.

CO, = ~~ nil

100:06

This gives the formula: — (O, OH), Na, (MgFe™), Fet, (SiA1), O,,.

The analysis and calculated formula show that the composition differs

from Riebeckite by having a higher percentage of MgO, and a moderate

amount of Al,0,. The presence of a small amount of TiO, is in keeping with

the abundance of rutile and ilmenite in the associated rocks.

Riebeckite and Glaucophane are miscible in all proportions (6), and the

formula of the Robertstown mineral indicates major replacement of Fe"? of

the Riebeckite molecule by Mg, and slight replacement of Fel"! by Al. The

optical properties agree more closely with those of Riebeckite than of Glauco-

phane. Hence the mineral may be termed a Magnesian Riebeckite.

VII. GENESIS OF THE CROCIDOLITE

The crocidolite described herein is associated with late magmatic soda

inetasomatized intrusions which show doleritic texture. Varying degrees of

tourmalinization ate also recorded. A feature of the final metasomatic

phases is the crocidolite, which has formed from iron-and-soda-rich solutions,

and has filled joint planes and fissures in the meta-dolerite, and in some

places has invaded the surrounding dolomite. The presence of a high per-

centage of magnesia in the crocidolite may be due to assimilation from the

dolomite by the late magmatic solutions,

The genesis of the crocidolite is thus probably related to late magmatic

activity associated with “doleritic” intrusions.

REFERENCES

Dickinson, S. B. “The Structural Control of Ore Deposition in some South

Australian Copper Fields,” Bull. 20, Geol, Surv., S.A., 66

Agmstronc, A. T, Mining Review, 86 (1947), 111

GarTRELL, H. W. Mining Review, 50 (1929), 40

Dickinson, S. B. Mining Review, 76 (1942), 84

Jack, R. L. Mining Review, 33 (1920), 53

Wares A. N. “Elements of Optical Mineralogy,” Pt. II, 1947, (Wiley),

GEOLOGICAL SURVEY, WESTERN AUSTRALIA, Bull, 100, 1942, 26.

Additional references to the Robertstown Crocidolite may be found in Min-

ing Reviews 16, 23, 36, 78, published by the S. Aust. Department of Mines.

“SI Awbhwh

THE LIFE HISTORY OF PLAGIORCHIS JAENSCHI, A NEW

TREMATODE FROM THE AUSTRALIAN WATER RAT

BY T. HARVEY JOHNSTON AND L. MADELINE ANGEL

Summary

. An account of the anatomy of Plagiorchis jaenschi from the Australian water rat,

Hydromys chrysogaster Geoff., var. fulvolateralis Gould, is given.

. Two apparently distinct forms are shown to be the same, the differences being

attributable to the state of preservation of the material.

. Infection of Lymnaea lessoni was accomplished experimentally. This is believed (but

not proved) to follow ingestion of the eggs.

The various stages in the life cycle, excluding the miracidium, are described.

The cercaria encysts in mosquito larvae, and also in crustaceans, Daphnia, Chiltonia and

Cherax, of which the last-named, the yabbie, is believed to be the normal secondary

intemediate host. Similar cysts have been found in yabbies from Tailem Bend. The

cercaria also encysts, though rarely in the liver of the host snail.

Natural occurrences of the cercaria are recorded from Wood’s Flat and Bow Hill; but it

has not been found at Tailem Bend.

THE LIFE HISTORY OF PLAGIORCHIS JAENSCHI,

A NEW TREMATODE FROM THE AUSTRALIAN WATER RAT

By T, Harvey JoHNston and L. MapEnrNe ANGEL *

[Read 12 October 1950]

SUMMARY

1. An account of the anatomy of Plagiorchis jaensché from the Australian water

rat, Hydromys chrysogaster Geoff., var, fulvoloferalis Gould, is given.

2. Two apparently distinct forms are shown to be the same, the differences

being attributable to the state of preservation of the material.

3. Infection of Lymnaea lessoni was accomplished experimentally. This is

helieved (but not proved) to follow ingestion of the eggs.

4. The various stages in the life cycle, excluding the miracidium, are described.

5. The cercaria encysts in mosquito larvae, and also in crustaceans, Daphnia,

Chiltonia and Cherax, of which the last-named, the yabbie, is believed to

be the normal secondary intermediate host, Similar cysts have been found

in yabbies from Tailerm Bend, The cercaria also encysts, though rarely, in

the liver of the host snail,

6, Natural occurrences of the cerearia are recorded from Wood's Flat and Bow

Hill; but it has not been found at Tailem Bend,

The type as well as other representatives of the adult and larval stages have

been deposited in the South Australian Museum, Acknowledgment is made of

the generous assistance rendered hy Messrs. G, G. and B, Jaensch of Tailem

Bend and J. Brook of Bow Hill, The investigation was carried out in connection

with the Commonwealth Research Grant to the University of Adelaide.

Plagiorchis jaenschi has been found in the lowet part of the small intestine

of six out of seven water rats, Hydromys chrysogaster Geoffr., var. fulvolateralis

Gould, trapped by Messrs, G. G. and Bryce Jaensch along the banks of the River

Murray at Tailem Bend—May 1938, April 1945, March 1947, May 1948, Decem-

her 1949 (in one of two taken) and April 1950; also in all three Hydromys

obtained for us by Mr. J. Brook from Bow Hill, near Mannum, also on the

Murray, in April 1950, A water rat from Berri, May 1948, and one from the

River Torrens, Adelaide, in July 1923, did not contain this trematode, The

maximum number obtained on any one occasion was eighty, the worms being in

various stages of growth. Fragments of the Murray prawn, Palagmon australis,

and the yabbie, Cherax destructor, were usually present in the digestive tract,

Because of unavoidable delay in examining the dead rats, the worms had in some

cases become rather macerated before being collected, but these relaxed parasites

permitted a more ready examination of the reproductive system. In two cases the

parasites, when found, were much smaller and very strongly contracted, so that

the reproductive organs were crowded into a small space. These latter worms

were well preserved, Because of the marked dissimilarity in size and appearance

it is proposed to refer to the two forms separately, the relaxed worms being

desctibed first, The type specimen belonging to this latter group is deposited along

with paratypes in the South Australian Museum.

Egg-hearing specimens with pigniented vitellaria ranged from ‘85 to

143 am, in length and +23 to ‘37 mm. in maximtim breadth, most of them being

between -93 and 1-0 mm. Jong and about -3 mm wide, Worms which reached

= University of Adelaide,

Trane Roy Soc, S. Aust,, 74, (1), March 1951

the egg-bearing stage but which stil contained very few eggs (1-20), measured

from +70 to °77 mm. in length and +2 to -24 mm. in breadth, Nearly all relaxed

specimens under ‘74 mm. in length had not yet become ovigerous, although a

worm “71 mm. by :22, and another *73 by *22, both possessed yolk follicles

almost as numerous as they were in the smallest egg-bearing parasites. A worm

“72 min. long possessed a single egg and its vitellaria were scanty, linear in

arrangement and devoid of pigment. The worms were broadly rounded

anteriorly, widest at the level of the oesophagus, and tapering very gradually to

the level of the posterior testis, when they narrowed rather rapidly to terminate

in a rounded tip.

The ventrally-directed oral sucker in ovigerous worms is approximately

spherical, *16-°17 mm, in diameter, and the acetabtiium +125--15 mm. in

iameter, though sometimes both suckers may be slightly wider than long or longer

than wide. The oral sucker is thus somewhat larger than the ventral. The front

end of the latter in mature worms is at about one-third of the body length. In

immature relaxed worms the lengths of the anterior and posterior suckers aré in

the ratio af about 4:3, but in ovigerous specimens it is about 6-7:5, In worms

*36 to *54 mm. long the oral sucker is about "1 mm. in diameter and the acetabu-

lum ‘075 mm. These dimensions become increased (1175 by °125-~°15 mm.) as

the worms become ovigerous, but do not increase further though the parasites

may become much longer, It is more particularly the postacetabular region which

increases in length as growth proceeds. In a worm -36 mm. long the length of

that tegion is 35% of the total body length; in those -43--47 mm. long, 39%;

in a worm ‘54 mm, long, 439%; in a worm *73 mm. long and almost ovigerous,

47%: in a worm *74 mm, long and just ovigerous, 59%; in a worm 1-43 mm,

58%, The sex pore is at about +35 mm. from the head end, and close behind the

poirt-of bifurcation of the intestine. Spination, though evident in contracted

worms, had disappeared from all relaxed specimens. Young worms may show

the typical Y-shaped excretory bladder in preserved material.

The prepharynx is very short and lies above the hind edge of the oral sucker.

The pharynx is spherical (-08 mm. diameter) or slightly elongate. The narrow

oesophagus is very short, measuring about one-quarter or one-fifth of the length

of the pharynx. The crura diverge almost at tight angles to the longitudinal

axis of the body and then curve posteriorly to Jie more or less parallel with the

edge of the body, their course being slightly sinuous. They terminate beside the

posterior part of the stem of the excretory bladder.

The testes are each about *17 mm, in diameter, though the posterior one tnay

be rather narrower, The cirrus sac is relatively large and takes its origin at

about the ovarian level, but on the opposite side. It then curves around and ahove

the right side of the acetabulum, then inwardly and downwards, and approaches

the metraterm as the two organs pass forwards to the genital pore, The sac

asses directly ventrally ta enter the latter. The length, measured along the curve,

is about “45 mm. and its breadth about -07 mm. The posterior half or two-thirds

of the organ serves as a seminal vesicle. Occasionally the sac lies in 2 more median,

sinuous position, crossing above the acetabulum. The cirrus, when at rest, is

closely folded im the anterior part of the sac, The fully extruded unarmed cirrus

is about ~46--+53 mm. in length, and its width 15-17 » except in the vicinity of

its base where the breadth is about 42 p. -

The rounded ovary, ‘O8 by -1 mm., is situated on one side a short distance

behind the acetabulum, portion of the citrus Sac lying between the two organs,

The oviduct passes inwards and posteriorly to meet the common yolk duct in

the vicinity of the shell gland, the latter lying between the ovary and anterior testis,

The uterus soon bends posteriorly and travels in a sinuous course between the

testes, reaching almost to the level of the ends of the crura before returning

as the ascending limb which lies beside the descending limb, About the level of

the shell gland, the ascending duct is thrown into a few loops as it makes its

way to the left side of the worm, It passes below the nner end of the cirrus sac

and then forwards in a ventral position beside (or sometimes above) the aceta-

bulum, The metraterm is thin-walled. The yolk glands are extensive, covering

the crural region and almost reaching the lateral edges of the worm. They extend

from the level of the oesophagus to the free ends of the crura, terminating just

behind, or just in front of, the posterior loops of the uterus. The follicles are

irtegularly rounded (12-15 diameter) or elongate. The two fields remain

separate though some scattered follicles may occur in the oesophageal region

between the lateral felds, The Jatter may approach very closely at their posterior

ends. If we recognise the subgenus Multiglandularis, which is based on the dis-

tribution of the vitellaria, then our species would be P, (M-.) juenschi, The

main yolle duets lic dorsally and transversely just in front of the anterior testis

There is a definite yolk reservoir. Eggs are 30-37» long by 17 - 22 » wide, most

of then: being 32-34» by 17-20 p.

Strongly contracted worms taken in June 1941 were, as stated above, well

preserved when compared with those just described. The spines were short but

abundant on the anterior region, becoming very low and scarcely recognisable

under high power behind the level of the acctabulum. Similar spination was seen

on metacercariae. Egg-bearing worms measured *21-°56 mm, long by “145 to

-25 mm. broad, the smaller individuals tending to be relatively wider than the

longer, Those which were not ovigerous ranged from ‘14 to *31 mm. in length

and ‘O88 to °22 mm. in width. All strongly contracted worms were plump, with

broadly routed extremities and with a more or less marked ventral concavity

involving the acetabulum and the region in front of it, sometimes extending to

the oral sucket, Two cysts found in one host animal containing contracted worms

measured ‘f1 by ‘O87 mm. and -15 by ‘112 mm,, the Jatter having the stylet

still in situ. A metacercaria freed from a cyst was "137 by -12 mm. These sizes

fall approximately within the range uf dimensions of cysts obtained from experi-

tenitally infected crayfish (1204 by 98 « to 173 by 158 p; average 150 by 124 yx).

In the larger strongly contracted worms the suckers tend to be father

broader than long, the oral sucker up to ‘075 mm, long and -12 mm. broad, and the

acetabulum -07 by ‘095 mm., the latter tending to become nearly as wide as, but

shorter than, the oral sucker, In smaller mature worms the dimensions of the

suckers are less than those just given, The pharynx may overlap both suckers

in very small worms, but in those which are somewhat larger the organ lies above

the posterior end of the oral sucker, -

The various organs in these strongly contracted worms occupy the same

relative position as in relaxed specimens, but the testes (and to a less extent, the

ovary) are markedly compressed to become transversely elongate. Eggs in. such

syle a within the range found in the more clongate material (40-320 by

- & e

Our species is closely related to P. muris {Tanabe 1922) trom rats and mice

in Japan, ‘Tanabe’s Japanese paper was translated by Dolifus (1925), who repro-

duced the figures also, Yamaguti (1933, 106) added further details, Hirasawa

and Asada (1929, 507) dealt with its life cycle. Olsen 1937, pl, v. 73) repub-

lished Dollfus’ figure of the adult worm. McMullen (19378, 113) reported

experimental infection of rats, mice, pigeons and man with P. muris, The vitelline

follicles are indicated in Dollfus’ figure as extending a litt'e further forward than

in MeMullen’s (1937) figure, ‘Tanabe stated that the intermediate hosts in

Japan were Lymuoea perzia and Chironomid larvae. McMullen (19376, 239)

riefly described the species from North American materjal, as also did Cort

and Ameel (1944, 37-48). Ishii (1935, 629) in an extensive survey of the rats

(varieties of Rattus norvegicus) occurring in the drains and rivers of Tokyo,

found four species of trematodes; three of them were echinostomes and the fourth

was Clonorchis sinensis, but Plagiorchts muris was not mentioned,

- If Olsen’s key (1937) to the species of Plagiorchis be used, our parasite

would be accommodated beside P. muris, The latter was placed by Schulz and

Skworzow (1931, 773) in their subgenus, Multiglandularis, and Olsen has fol-

lowed them.

Fig. 1, adult; 2, strongly contracted adult; 3, very young, contracted worm;

4, anterior end, side view; 5, metacercaria, wmfxed, somewhat compressed

(expressed from a cyst ftom Lymnaea lessoni).

REFERENCE TO LETTERING

al, alimentary caecum; ¢, cirrus; cs, cirrus sac; cb, excretory bladder; ep, excre-

tory pore; gp, genital pote; o, ovary; ov, probably ovary and shell gland complex;

r, refractile granules; sg, shell gland; tl, +2, testes: u, uterus; y, yolk field;

yd, vitelline duct.

P. (M.) jaenschi, in its yelaxed condition, differs from P. (M.) muris in the

following features: much shorter and narrower dimensions; much smaller oral

and ventral stickers, testes and ovary; genital pore close to the intestinal bifurca-

tion; ovaty nearer the acetabulum postetior testes more remote from the end of

the worm; and yolk follicles less abundant at the posterior end where the two

fields are almest separated.

EXPERIMENTAL INFECTIONS

Lymnaea jessoni” has been infected with eggs of Plagtorchis jaenschi in

three separate experiments. The eggs were dissected out from the adult worms

and placed in contact with various molluscs, after varying periods. A summary

of all experiments performed follows :—

Experiment A, 26/3/47. Eggs (dissected out from a number of adults from

Tailem Bend) put in a petri dish containing snails, including 8 Lymmnacae. Snails

isolated over 24-hotir period once a week from eighth week onwards; after

15 weeks one of two surviving Lymnaeae emitting large numbers of cercariae,

The second snail died in 21 weeks; and although no cercariae had been recovered

during the weekly testings, the liver was found to contain many sporocysts and

some cercariae which were probably immature, (The six other Lymnaeae died

after two to nine weeks; none showed sporocysts on dissection. )

Experiment B, 20/12/49. Eggs (Tailem Bend) dissected out and placed on

lettuce in dish containing 6 Lymnaeae and other snails, The 6 Lymnaea died

within 10 days. Sectioning revealed no evidence of development, or even of

ingestion of the eggs.

Experiment C. 14/4/50, Eggs teased from 8 adults (Tailem Bend); kept

in water for four days, then fed on letttice to various snails. Of these, the four

Lymnaeae died in 4, 16, 17 and 21 days; they were dissected carefully, but no

signs of infection were toted.

Experiment D. 17/4/50. Eggs from eight adults (Tailem Bend) teased out;

kept in water for nine days (26/4/50) before feeding on lettuce to snails, Snails

isolated over 24-hour period once per week from 24/5/50. Lymnaea (1)

emitted cercariae on 14/6/50, (Infection period thus between six and seven

weeks.) The three remaining snails were then kept isolated in tubes (being fed

on lettuce). Lytinaea (2) gave cercariae.on 15/6/50; and Lymnaea (3) on

21/6/50. Lymnaea (4) died on 7/7/50 (i¢., 72 days after infection) ; on dissec-

tion it was found to be harbouring cercariae and a few sporocysts,

Experiment E, 27/4/50. About 18 adults (Bow Hill) were teased up (in

the dish in which they had heen lying for several days, and which therefore pro-

bably contained some naturally laid, i¢., mature, eggs as well). On 4/5/30 the

eggs were pipetted on to lettuce in a dish with 6 Lymsnaeae and other snails. The

snails were isolated once pet week from 24/5 to 21/6/50, and thereafter examined

daily. Three of the Lymnaeac became infected; two gave off cercariae after

67 and 74 days respectively, the infection being very light in both cases. The

third snail died after 104 days; it had never given off cercariae, but on dissection

was found to contain a number of immature sporocysts.

It is believed that infection of the snails occurs by ingestion of the eggs, as

is the case with many Plagiorchids, In Experiment D, Lymnaea (1) emitted

cercariae six to seven weeks after it had been placed in contact with eggs, This

is regarded as a comparatively short period for development at this time of the

year (Aprilto June}. If a free-swimming miracidium were produced, this period

would necessarily be shortened,

SS Ee ——E—————ee

: ®) The Lymmaeae were known to be uninfected, having been hatched and reared

in the laboratory.

According to McMullen (1937b) Tanabe reported that the fully developed

miracidium of Pligiorchis muris was produced in 96 hours. Dollfus, 1925,

reported that the egg when laid contained an egg-cell and 5-6 yolk-cells, and that

development of the miracidium was completed in four days at 37°. He did not

state whether the miracidium hatched at this time, however, McMullen (1937 b)

kept eggs of the American species, from man, at the prevailing August and Sep-

tember temperatures m1 Michigan. and noted that they did not produce miracidia

under 24 days, Our experiments did not show what period after the egg is laid,

if any, is required before the miracidium becomes viable,

Other molluscs used in the experiments wete Amerianna spp., Planerbis

tsingt, and Notopala hanleyi. None of these became infected.

C, Plagiorchis jaenschi had not been identified as a natural infection of

Lymnaea lessoni until April 1949, when it was found in 5 of 45 Lymnaea, from

Wood's Flat. It was found at Bow Hill in February and April 1950, in 1 of

1,072 and | of 460 of the snails, respectively. It has never been recorded from

Tailem Bend, where it would not be expected to be a common form, in view of

the few Hydromys which now frequent the swamps in that region; though cysts,

believed to belong to Plagiorchis jaenschi, have been found twice in yabbies from

Tailem Bend. It should be noted that once or twice we have noted “stylet

cercariae” from Lymnaea, without further identification; on the other hand, when-

ever these cercariae were examined more closely, they proved to be a form with

stylet 24 » long. This latter form is the only common xiphidiocercaria found by

ts in, Lymnaea lessoni,

Tue Speorocyst

Sporocysts were present in the livers of the snai!s in large numbers in the

origina! infection, but less in the later experimental hosts, They are compara-

tively small, each containing from 2-4 cercariae. Average of 7 (not fixed)

G45 by 202 p; range 450 to 825 u by 150 to 240».

The cells of the sporocyst wall, and the contained cercarise, stained well with

a weak solution of basic fuchsin im normal saline, No germ balls were seen; and

no details of the excretory system were determined. Tiny green refractile

droplets were present throughout the sporocyst wall.

THe CERCARIA

In general, cercariae emerge from the snail in the early hours of the morning,

mostly before 9 am. (On one occasion, when no cercariae had been given off

earlier in the day, quite a large number emerged between 1 and 2 p.m.)

Fer the rest of the merning, the cercariae remain suspended in the water,

swinwuing only occasionally, After this they become concentrated at the hottom

of the test tube, some of them fastened by the stickers to the tube; sometimes they

appear to favour the side nearest the light, but at other times there is no obvious

phototactic response. At the end of the day they lie on the bottom of the tube;

same of them even attempt to encyst. (It 1s doubtful whether such encystation

preserves their lives, as there was no. movetnent in those “‘metacercariae” which

were removed from the rather ragged, gelatinous coating, Cyst formation was

observed several times on the slides—adverse conditions, such as drying out, or

perhaps the pressure to which the cercaria was exposed under a coverslip, appear-

ing to stimulate it.) The length of free life may, howéver, be longer than in

many cercariae, for, from the first snail to be infected, a number of cercariae

over 48 hours old successfully encysted in DaphAnin sp,

Measurements of formalinised specimens were subject to some variation,

due to the varying states of expansion in which they were fixed, A series of

20 which had been killed at 5 p,m, by adding boiling 10% formalin to an equal

yolume of a very weak solution of neutral red, in which they had been placed for

ten minutes, ranged from 133 to 187» im body length, and from 94 to 148 in

breadth; the average size being 155 hy 120», Ten cercayiae similarly treated,

but killed at 11 am,, ranged from 150 to 188, in length and 98 to 128, in

breadth: the average size beitig 173 by 13m. (That is, early in the day the

cercariae appear to be fixed in a more extended condition.) The tail measure-

ments are only approximately accurate, due to the fact that the tails were seldom

fixed in a perfectly straight condition, They ranged in length from 102 to 162 p,

and in breadth from 26 to 36s. an average of 24 specimens (frot cercariae fixed

in both morning and afternoon) being 132» by 29. The measurements of four

obviously extended specimens were:—body 255 to 285, long and 82 to 90m

wide (average 270 by 86,); tail 158 to 180» long and 26 to 32 wide (average

172 by 29 n).

The oral sucker was larger than the ventral, approximate measurements for

the former being 412 long by 53 wide (average of 20 specimens); and for

the latrer 32 » long by 38» wide (average of 10 specimens).

The stylet (fiz, 3) is 34 long; 9°5y: across the widest point, and 6-5

across the base. The thickened rim is about 3p deep, It does not extend right

round the stylet, being incomplete on one face. Tt starts 10 from the tip and

from 13 » the rernainder of the “collar” narrows in gradually to a point 15 from

the base, from which the width remains uniform.

About 20 of the length of the tail is enclosed within the body in a caudal

pocket which is lined with spines. The pocket may he well retracted into the

bady, or may be opened out so that the hinder part of its side walls comes to le

on the posterior end of the body. In this region of the pocket the spines, pro-

bably about ten on each side, are much longer than elsewhere, and may be seen

even in the retracted condition. In the everted position of the pocket they appear

as short bristles. After prolonged exposure to a neutral red solution so dilute

that it was almost colourless, the walls of the pocket were consistently stained an

orange colour, though no other parts of the body were affected by the stain in

this dilution, ,

The general body surface is covered with extremely minute spines which

are more prominent anteriorly, and cease to be really obvious at about the

acetabular region. Greenish refractile granules, which are mostly fairly large,

are more or less evenly distributed throughout the body, except in the region

anterior to the pharynx, which is free of them (fig: 7).

There is a mass of gland cells extending from about mid-way between the

two suckers. to just beyond the posterior border of the acetabulum (fig. 7).

Intravitam staining was not of much assistance in determining the number of

these cells, which ts thought to he at least 10 pairs, and possibly a number more.

With neutral red, the three or four large posterior cells show very fine granula-

tion, while the anterior mass takes up the stain quite deeply, The muclet appear

quite clear, and very faintly pink, after basic fuchsin and normal saline. The

ducts of the gland cells are often bent upon themselves, or dilated here and there

in their course. Some of these, also, show a fine granulation. They run forward

together, becoming narrower as they do so, to open near the mouth. Methylene

blue stained the cercaria a uniform, very fait, blue, but showed no differentiation

at all.

The prepharynx is short and very inconspicuous; the pharynx quite well

defined and muscular, but the oesophagus and alimentary crura so inconspicuous

that in living specimens there is rarely any indication of their presence. In

stained, fixed, specimens they can be distinguished as very narrow structures,

one cell in thickness, so that even the existence of a lumen ts problematical, The

caeca appear to diverge abruptly from the oesophagus.

The excretory system is seen best with the aid of basic fuchsin in normal

saline. Cercariae will live all day in good condition for examination in very

dilute solutions, Horse serum in addition is also helpful, The posterior part of

the Y-shaped excretory bladder opens into the vestibule, from which the excretory

pore opens on to the surface of the body, The main excretory tubes open into the

cornua of the bladder at the tips, but we had considerable trouble in determining

Fig. 6, 7, cercaria: 6, fixed specimen stained with borax carmine in lacto-phenol;

7, details from living specimens, Fig. 8, stylet; 9, two cysts in common envelope;

10, ‘one of the variations in the shape of the bladder.

Fig, 6, 7, to same scale; 8, sketch; 10, sketch,

this because of the presence of cystogenous cells and refractile granules in the

area, the twisting of the main and accessory excretory tubes, often over the end

of the cornua, and the variability in shape and definition of the arms of the

bladder. We. mention this to illustrate that in some cercariae, without prolonged

study too much reliance cannot be placed on the supposed point of entry of the

main excretory tubes.

The canals divide into anterior and posterior collecting tubules at the level

of the anterior borders of the excretory bladder. There are three groups of

three flame cells connected with each of the anterior and posterior collecting

tubules, The excretory formula is thus 2 ( (3-+3+43)+(3+4+3-+53)).

Although the figure (ig. 7) shows that in some of the groups the whole six

elements ( three tubules and three flame cells) were not seen in the cerearia, the

determination of the excretory formula was made with additional information

supplied by a study of a metacercaria seven days old, in which no less than 27 of

the 36 flame cells were seen, the positions of these filling in the gaps left in the

excretory picture of the cercaria.

The genital primordium cotisists of a collection of quite undifferentiated cells,

but from the relative positions and atratigement of these cells the anlagen of the

adult organs can be diagnosed (fig. 6),

Tue Cyst

_ The cercariae have been found, experimentally, to encyst in Daphnia sp.;

the amphipod, Chiltonia subtennis; the yabbie, Cherax destructor, and in mosquito

larvae; but not in the molluscs, Amerianna spp., Planorbis isingi, Lymnaea lessont,

Plotiopsis tatei and Hyridelia australis, or in tadpoles of Limunodynastes sp. or the

fish, Gambusia affnis, In the liver of one of the Lymnaeae naturally infected

with the cercaria (from Bow Hill) , three cysts which fell within the size range

for Plagiorchis jaenschi, and contained stylets of the same size, were found;

these were obviously cysts of Plagiorchis jaenschi, The metacercaria expressed

fram one of them is figured in fig. 5. McMullen (1937 a, b,) reported that cercariae

of P. muris and P. proximus encysted within the sporocyst. We have not

observed this with P, jaenschi,

Among the four arthropods, encystation takes place most readily in the

yabbie, and this is probably the natural secondary intermediate host, forming,

as it does, a large part of the food of Hydromys. On at least two occasions (in

April 1939 and February 1940) we have found cysts in the gills of yabbies from

Tailem Bend, These resemble those of P. jaenscht in general appearance and size,

and in the site which they occupy.

The cysts were found occasionally in the joint region of the legs, but were

predominantly in the main stem of the gills, Sometimes two, three or four were

enclosed in series in the same piece of integument, though each had its own cyst

wall (fig, 9). The cysts vary in shape from spherical to elliptical. In a series

of 15 from the original infection the size range was from 120 by 98,4 to 173 by

158 »; cysts of the naturally occurring form from Bow Hill ranged from 120 by

98 » to 210 by 128 n, and even to 200 by 180 in one cyst from a mosquito larva

THE METACERCARIA

A metacercaria seven days old was excysted successfully; as mentioned in

the description of the cercaria, the excretory formula was thought to be no

further advanced, The stylet was still in position in the oral sucker, as it appeared

to be in two other cysts of the same age. Metacercatiae which were liberated

from cysts three months old were relatively small and showed no very great

adyance in development in those features which could be studied in stained

specimens. The genital primordium did not show up even as clearly as in the

cercaria, but appeared as a U-shaped string of ceils situated in the region dorsal

to the acetabulum; this is probably the primordium of the cirrus sac and metra-

term. In an average of three stained specitnens the oral sucker measured 53 pw

long hy 68 wide, and the acetabulum was 27» long by 39p wide. We were

unable to excyst these metacercariae in sufficiently good condition for studying

the excretory system,

In the metacercariae obtained from the host Lymnaea (of which, of course,

the age is not known) the alimentary system had developed considerably and

closely resembled that of the adult. Although the metacercariae were motile, we

were unable to determine any excretory detail, i

LITERATURE

_ Cort, W. W. 1944 The germ cell cycle in the digenetic trematodes, Quarterly

Review Biology, 19, (4), 275-284

Corr, W. W., and Amezt, D, J. 1944 Further studies on the development of

the sporocyst stages of Plagiorchiid trematodes. Jour. Parasit., 30,

-56 \

Cort, W. W., and Oxtvier, L, 1941 The early developmental stages of

Plagiorchis muris (Trematoda). Jour. Parasit. 27, Suppl, Abstr.,

11-12

Cort, W. W., and Oxrtvier, L, 1943 The development of the larval stages of

. Plagiorchis muris Tanabe, 1922, in the first intermediate host. Jour.

Parasit., 29, 81-99

Dottrus, R. P. 1925 Distomiens parasites de Muridae du genre Mus. Ann.

Parasit., 3, 85-102, 185-205

Hirasawa, K., and Asana, J, 1929 Studies on the life history of Lepoderma

muris, etc, Tokyo Iji Shinshi, 1929, 507-516, (In Japanese; not

available) _

Isuit, N. 1935 Studies on rat trematodes. Jap. Jour. Exp. Medicine, 13, 629-630

McMutten, D. B. 1937a An experimental infection of Plagiorchis muris in

man. Jour. Parasit., 23, 113-115

McMutten, D. B. 1937b The life histories of three trematodes parasitic in birds

and mammals, belonging to the genus Plagiorchis. Jour. Parasit., 23,

235-243

McMutten, D. B. 1938 Observations on precocious metacercarial develop-

ment in the trematode superfamily, Plagiorchioidea. Jour. Parasit.,

24, 273-280

Massrno, B. G. 1929 Die Trematoden der Gattung Plagiorchis Lithe 1889

der Vogel Russlands, Zentr. Bakt., IJ, 78, 125-142

Ousen, O. W., 1937 A systematic study of the trematode subfamily Plagior-

chiinae Pratt 1902 Tr, Amer. Mier. Soc., 56, 311-339

Scuutz, R. E., and Skworzow, A. A, 1931 Plagiorchis arvicolae n.sp., aus der

Wasserratte. Z, f, Parasitenk., 3, 765-774

Tanase, H. 1922 Contributions, etc. On Lepoderma muris n.sp. (In Japan-

ese), Okayama Igakk, Zasshi, No. 285, 47-52

Yamacuttr, S. 1933 Studies on the helminth fauna of Japan. Part I. Trema-

todes of birds, reptiles and mammals. Jap. Jour, Zool., 5, 1-134

CRASPEDACUSTA SOWERBYI IN SOUTH AUSTRALIA, WITH SOME

NOTES ON ITS HABITS

BY I. M. THOMAS

Summary

1. The occurrence of Craspedacusta sowerbyi Lankester in South Australia is noted and some

comments made on its distribution throughout the world.

2. The organisms have been observed to feed on a variety of small Crustacea and also on small

mosquito larvae. An increase in rate of pulsation is indicated in the presence of Daphnids

but the relation of this to feeding is not proven.

3. Medusae show no response to incident light.

4. Medusae show a marked contraction of the velum at low temperatures and are incapable of

swimming movements at temperatures below about 13°C.

CKASPEDACUSTA SOWERBYI IN SOUTH AUSTRALIA, WITH SOME

NOTES ON ITS HABITS

By I, M. Tuomas *

[Read October 12 1950]

SUMMARY

1, The occurrence of Craspedacusia sowerbyi Lankester in South Australia is

noted and some comments made on its distribution throughout the world.

2, The organisms have been observed to feed on a Variety of small Crustacea

and also on small mosquito larvae. An increase in rate of pulsation is

indicated in the presence of Daphnids but the relation of this to feeding

is not proven.

3. Medusae show no tesponse to incident light.

4. Medusae show a marked contraction of the velum at low temperatures

ant are incapable of swimming movements at temperatures below about

The genus of freshwater medusae, Craspedacusta, is now known to be widely

distributed throughout the world. It was first described from specimens taken in

the Victoria regia tanks in Regent's Park, London, in 1880 by Lankester (1880).

It has since been recorded from other parts of England, Europe, North America,

Bere Asia and now an occurrence has been recorded from Australia (Thomas,

Several species have been described but the validity of some of them is now

in doubt. C. (Limnocodium) sowerbyi was established by Lankester from material

in Regent’s Park, while C. ryderi which has been found in some cighteen of the

States of North America is now, according to Boulenger and Flower (1928),

believed to be identical with it. C, kawaii was described from material in the

Yangtse River in China by Oka (1907), but it is likely that this (Tang, Yang

and Fang (1936) ) is only a variety of C, sowerbyi. C. germanica was described

by Persch (1933), mainly from the hydroid stage, but this again seems to be

synonymous with C. sowerbyi (Boulenger and Flower 1928). C. tseana

described from material found in a well in the province of Ise in Japan by Oka

(1922) does differ in sufficient detail, e.g., smaller total number of tentacles,

absence of ring canal, position of the lithocysts at the bases of the tentacles and

the isolated arrangement of the nematocysts, to justify its separation,

It seems that the other three species, viz., C. sowerbyi, C, kawaii, and

C. germanica may be resolved into the single species C, sowerbyi. If this is the

case, its occurrence on four of the world’s five continents is remarkable.

Furthermore, the localities in which it has been found in various parts of the

world calls for comment. Of some twenty-nine occurrences in the United

States between 1932 and 1938 (Schmitt (1938) ), nineteen were in artificial

waters such as garden ponds, tanks, aquaria, gravel and clay pits and reser-

yoirs. More recently, Dexter, Surrarrer and Davis (1949) have recorded the

medusa from the States of Ohio and Pennsylvania. Some eighteen records

are mentioned of which only six are from natural expanses of water, one

being a slow flowing stream. In Great Britain and on the Continent, all its

occurretices haye been in artificial bodies of water (e.g., Tattersall (1933) and

* Department of Zoology, University of Adelaide.

‘Trans, Roy Soc. S. Auist., 74, (1), March 1951

van Someren (1933), though Totton (1929) believes that it is “highly prob-

able that Craspedacusta occurs in a wild state in British river systems." There

is no direct evidence of this as yet however. In Eastern Asia, apart from C.

kawaii, which is widespread in the Yangtse and its tributaries, all its appear-

ances have been in similar locations. The single Australian record is from

an extavated reservoir, (Thomas 1950).

The predominances of occurrences in artificial waters may have two pos-

sible explanations It may be that such localities are more frequently and

more closely observed so that the short-lived medusae would be more likely

to be noted when they appear, or it may be that artificial ponds and the like

are more frequently stocked with vegetation from other sources this intro-

ducing the hydroid form in mud containing frustules, In at least one case,

importation can be attributed to this cause. Amemiya (1930) noted the sud-

den appearance of medusae in his laboratory aquarium in Tokyo not long

aiter he had introduced into his tanks some water plants imported from San

Trancisco. In most cases, however, the medusa appears suddenly in fairly

large numbers in waters where there is no record of the recent introduction

of new plants or animals. The hydroid stage ts capable of reproducing

asexually hy transverse fission, frustule formation, and bud formation

(Persch, 1933) and can presumably remain viable in these forms for long

periods, medusae being produced only when conditions are favourable, Once

the latter have appearcd, most records show that their production ts repeated

annually at about the same season for some years.

There is little direct evidence of the ability of the hydroid or its frustules

to resist desiccation, Their formation has been described in detail by Persch

(1933) but he does not mention any form of encapsulation. Payne (1924),

however, states that the hydroid bears a covering which is “more than a slimy

mucous secretion” and figures it as having a layered structure. Mud and

détritus particles adhere to this. Frustules may be able to develop a similar

protection, Dissemination of the organism must then be in mud carried on

the roots of transplanted vegetation or possibly on the feet of water birds.

The natural céntres of occurtence of Cresprdacusta seem to be North

America and the Yangtse, and from these sources it has been conveyed hy

natural or artificial means to other parts of the world. It is impossible to say

at present with any degree of certainty from which of these regions the farms

found at Thorndon Park Reservoir near Adelaide emanated, There is no evi-

dence of either plants or animals having been deliberately introduced since

the opening of the reservoir ninety years ago though some English perch

have become established there, probably having come from entering streams

or from other reservoirs which now feed into Thorndon Park. The reservoir

bas now no significant natural inflow but it is maintained as a storage tank

being filled by gravity from other reservoirs higher in the hills behind it, In-

vestigations have failed to disclose the presence of medusae in these even

though there is a weekly routine examination by officers of the Engineering

and Water Supply Department.

The first specimens were seen on March 7th, 1950, and several visits in

succeeding months showed their presence in vatying numbers up until June,

sittce when none have been seen. The numbers of specimens taken on dif-

ferent dates in this period are indicated in Fig. 1. The points marked can-

not be regarded as being more than a rough indication of the number of

organisms present as weather conditions influence considerably the ease with

which they can be seen in the water. An overcast sky and a moderate breeze

rnffing the surface make their observation more difficult. All visits were

made in the early afternoon. Specimens were caught with a hand net from

a boat, Approximately an hour was spent on the lake on each occasion.

There appears to be a marked peak in abundance at about the end of April

and the beginning of May, the surface water at this time being between 16°

and 17°C. All medusae taken were female. Their gonads ripened at about

this peak period of abundance. Medusae caught varied in size between lcm.

and 1:9cm., the larger specimens being taken at the period of peak abundance.

Medtsae were always found most abundantly in about the centre of the

lake, where the depth is thirty feet or more, On no occasions were they seen

towards the sides in less than ten or twelve feet of water. Even when fairly

strong breezes caused appreciable surface currents, still no specimens were

we to

Oo wi

°%,

Surface Temp,

Moreh April May June July

Fig. 1

Heavy vertical lines indicate the abundance of Craspedactssia

at different dates. Points show surface water temperatures

on those dates.

seen near the leeward bank. Generally they occurred in loose patches of

about half a dozen individuals in several square yards, this being separated

by ten or fifteen yards from another similar patch. Their numbers were thus

considerably less than have been reported from scyeral locations in North

America where, for example, Cheatum (1934) records that in a small arti-

~ ficial pond near Dallas, Texas, a single scoop with a pint jar yielded as many

as sixteen specimens. Sufficient were brought back from Thorndon Park

to the laboratory from time to time to allow of some detailed observations «mn

their habits and to carry out some experitnents.

FEEDING

Specimens in the laboratory have been observed to feed on Daphnids,

Cyprids, small Amphipods and first and second instar mosquito larvae..

Daphnids were the commonest food and indeed the only type of food observed

in the gastrovascular cavity of those in the reservoir. If some of these were

placed in a finger bowl with a medusa, many of them were killed, presumably

by coming into contact with the nematocysts of the tentacles. Death was by

no means instantaneous because many escaped after being entangled with a

tentacle. Further, food organisms could be seen to be still motile after enter-

ing the gastrovascular cavity. The mouth is four-cornered and that part of

the gut enclosed in the manubrium is transversely ridged in such a way that

when the manubrium lengthens and shortens with each pulsation of the bell,

the food is forced further in. Once in the more spacious gastrovascular

cavity, the particle can float around more freely in the fluid it contains and

it may even penetrate not only into the base of a radial canal but also into

the lumen of a gonadial sac.

The tentacles were not observed to play an active part in the passing of

food to the manubrium but by unilateral contractions of the velum and a

imuftaneous flexing of the manubrium im that direction, the mouth could be

brought close to the tentacles. No passage of food in this way was ever ob-

served however.

To test the activity of the animals in the presence and absence of suitable

fwod, the following experiment was performed. Four medusae of about

equal size were placed in finger bowls each with 200ml. of water. Their tem-

peratures were maintained at 18°C, Rates of pulsation were noted at inter-

vals over a period of half an hour. Then to each of the first two bowls were

added 10m], of water at the same temperature and to each of the second two,

the same quantity containmg ten living Daphnids. Rates of pulsation were

again noted in the succeeding half hour, The results are summarized in

Table I. There is a mean difference of 9-1 pulsations per minute with added

Daphnids and @-8 in the controls, This indicates that the presence of Daphnids

does stimulate the medusae to greater activity, but further experiments would be

necessary to prove the matter conclusiyely,

Table |

Averaged Rates of Pulsation, each taken from ten readings, af Medusae

in the Absence and Presence of Living Daphnids.

Medusa No. 1 2 3 4

Control Period ... ode .. 85-0 86°8 82-4 84-8

Water only added = _.,. . 84-4 85°8 — —

Daphnids added .s 2 = _ 93°3 92-1

Differences =s + — 6 1:0 10-9 73

It bas been observed frequently that when a medusa strikes against a

solid object such as floating vegetation, or the bottom or sides of a jar, the

rate of pulsation increases. Swimming Daphnids may offer a similar stimu-

lus to more rapid pulsation, though whether this possible increase is of any

Significance in feeding has not been determined by the experiment described

nor by replicates of it as on no occasion were Daphnids taken into the mouth

though many were killed by contact with the tentacles. The increase in rate

of pulsation when a medusa comes in contact with a solid object as, tor

exainiple, submerged yegetation, was observed and commented upon by

Milne (1938), who says that this increase it activity frequently served ta

push the object to one side so that the organism could force its way past.

The present writer has frequently observed the same phenometion. Once the

obstruction was passed, pulsation rate fell to a more normal level.

REACTION OF LIGHT

Milne (1938) reports, as a result of observations on Craspedacusta taken

ai Crystal Lake, near Lynchburg, Virginia, that they have no apparent re-

action to incident light, Shadle and Minthorn (1939) on the other hand say

that when they found the medusae in a large pond in a gravel pit near Attica,

N.Y., they were more freqiient in the shadow of a pier. Cheatum (1934) re-

ports finding the medusae most abundantly under lily-pads and in the “ooze”

at the bottom of a shaflow pond near Dallas. He states, “Wading amongst

the lify-pads stirred up the “ooze” on the bottom and in areas where medusae

had not hitherto been visible, such riling of the water caused them to appear

in thousands.” Tang, Yang and Fang (1936), contrary to these findings,

report on a positive response to sunlight and electric light but found no re-

sponse to moonlight.

To check these findings, some medusae were placed in a long glass tube

about one and a half inches in diameter, filled with water and arranged hori-

zontally so that light could impinge on the organisms from either or both ends.

The experiment was of course carried out in an otherwise dark room. The

medusae, though quite active during the experiment, showed no reaction at

all to the direction of the light. Similarly when the tube was arranged ver-

tically, there was no apparent response. The use of red, yellow, green and

blue filters showed them to be equally unresponsive to any particular range

uf the spectrum. The experiment was repeated with medusae which had been

kept in complete darkness for five hours. After this treatment they were

slightly less active but still evinced no response.

ele)

Pulsations per Minute

5 Te) is 20 25

Temperature °C. -

Fig. 2

Influence of temperature on the rate of pulsation in Craspedacusta.

REACTION TO TEMPERATURE CHANGES

To test the responses of a medusa to lowered environmental tempera-

tures a specimen was placed in a finger bowl of water and then placed in a

larger basin containing water to which chipped ice could be added. The

temperature was reduced slowly after the organism had become acclimatised

for several hours at 22°5°C. The results are shown in Fig. IJ. It has already

been noted that the medusae increase their rate of pulsation when they strike

against a solid object. Points in the figure indicate, for the higher tempera-

tures, rates of pulsations in free floating specimens. As the temperature fell,

ccniraction of the velum became more strongly marked until at below about

145°C. the animal ceased to swim and sank to the bottom, where it continned

slower and more feeble movements as the temperature fell still lower. Be-

low 5°C. the animal was almost spherical, only a small round aperture re-

maining in the velum. The manubrium was completely retracted within the

sub-umbrellar cavity. Slight pulsations were maintained at a very slaw rate

down to 2°5°C. .

The temperature was allowed to rise gradually after about fifteen minutes

at this level and as it did so, pulsations became more frequent and stronger.

At 10°C. the velum was reasonably relaxed but it was not until between 14°

and 14:5°C. had been reached that normal swimming movements were recom-

menced. It is interesting to note that the medusae disappeared from the sur-

iace waters of Thotndon Park Reservoir when the surface water temperature

fell below 13°C. (see Fig. 1), If any remained in the reservoir at that date

they were presumably at or neat the bottom. The difference in temperatures

of cessation of normal swimming in the reservoir and under experimental

conditions, car be attributed to acclimatisation of the former to lower tem-

peratures.

The upper limit of temperature tolerance has not been determined here

but Milne (loc. cit.), gives it as between 25° and 30°C. for his specimens.

Specimens investigated by Tang, Yang and Fang (1936), in Amoy, showed

a temperature preference of 28°C., which was approximately the normal am-

-ient temperature.

They say that, in a long tube, the medusae moved from cooler and

warmer regions and congregated at this temperature. When cooled in

beakers from 28°C. movement became abnormal! at 31° to 35°C, and ceased at

36°. At 28°C. the rate of pulsation was about 120 per minute. The higher

temperatures tolerated by these specimens can be accounted for by their

acclimatisation to a high environmental temperature.

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PaoMae as 1950 “Craspedacusta sowerbyi in Australia.” Nature, 166,

Torron, A. K. 1929 “Freshwater Medusae in England.” Nature, 123, 912

vAN SoMERN, V. D. 1933 “A Scottish occtirrence of Craspedacusta sowerbyi

Lankester.” Nature, 132, 315

ADDENDUM

Since this paper went to press, a reprint of an article by P, L. Kramp

(“Freshwater Medusae in China”, Proc. Zool. Soc. Lond., 120, 165-184, 1949)

has been received. In this, the distribution of C. sowerbyi in China is discussed

and details given of a further species, C. sinensis, first described by Gaw and

Kung (Sci. Rep. Nat, Wuhan Univ., pp. 1-11, 1939). This co-exists with

C, sowerbyi in pools near Kaitung, Szechtien, though it is much less. abundant.

Kramp supports the contention of Sowerby (1941) that the Upper and Middle

Yangtse River Valley is the original home of the genus, whence it has been trans-

potted probably by human agency to other parts of the world, possibly in mud

on the roots of the water hyacinth (Aichhornta) or similar water plants.

Eichhornia has been introduced into Australia, and bade fair to become a

serious pest in the River Murray and other places until vigorous measures were

taken to control it. It has not, however, been reported from any of the Adelaide

reservoirs though it is still fairly common as a garden plant on the Adelaide

Plains. The Adelaide Hills region, which includes the drainage area of the

reservoirs, does not offer a suitable habitat for the growth of Etchhornia, so it

does not seem likely that this plant is the medium through which the coelenterate

was introduced into Australia.

Up to the presetit time (June 1951) no further specimens of the medusae

have been reported from the Adelaide reservoirs,

THE MORPHOLOGY AND LIFE CYCLE OF THE TREMATODE,

APATEMON INTERMEDIUS, FROM THE BLACK SWAN

BY T. HARVEY JOHNSTON AND L. MADELINE ANGEL

Summary

. The anatomy of the trematode, Apatemon intermedius (S. J. Johnston) from the duodenum

of the black swan, is described.

Hatching time of the eggs is about 33 days in early summer.

Cercaria lessoni, from the pulmonate molluscs Lymnaea lessoni, Simlimnea subaquatilis,

and Planorbis isingi, is its larva. Cercariae may be produced within 35 days of invasion of

the miracidium.

The second intermediate hosts are freshwater leeches, Glossiphonia spp., in whose bllod

vascular system the encysted tetracotyle occurs.

23-day-old metacercariae are compared with those of Cercaria burti Miller 1923 (Stunkard,

Willey and Rabinowitz 1941). In A. intermedius they are encysted at this stage.

Juvenile stages found in the black swan are described.

Two strains of A. intermedius, infecting respectively Planorbis isingi and Lymnaea lessoni,

are postulated.

In view of the wide separation between the reported types of snail host for A gracilis, viz.,

Bithynia (Szidat) and pulmonates (Stunkard et al.) in Europe and North America

respectively, we regard it as likely that two distinct species are involved.

THE MORPHOLOGY AND LIFE CYCLE OF THE TREMATODE,

APATEMON INTERMEDIUS, FROM THE BLACK SWAN

By T. Harvey Jomnston and L. MapEtine AnczL*

‘[Read 9 November 1950]

SUMMARY

1. The anatomy of the trematode, Apatemon intermedius (S. J, Johnston) from

the duodenum of the black swan, is described.

2. Hatching time of the eggs is about 33 days in early summer.

3. Cercaria lessoni, from the pulmonate molluscs Lymnaea lessoni, Simlimnea

subaquatilis, and Planorbis isingi, is its larva. Cercariae may be produced

within 35 days of invasion by the miracidium.

4. The second intermediate hosts are freshwater leeches, Glossiphonia spp.,

in whose blood vascular system the encysted tetracotyle occurs,

5, 23-day-old metacercariae are compared with those of Cercaria burti Miller

1923 (Stunkard, Willey and Rabinowitz 1941). In A. intermedius they are

encysted at this stage.

6. Juvenile stages found in the black swan are described,

7. Two strains of A. intermedius, infecting respectively Planorbis isingi and

Lymnaea lesson, are postulated.

8. In view of the wide separation between the reported types of snail host for

A gracilis, vie., Bithynia (Szidat) and pulmonates (Stunkard et al.) in

Europe and North America respectively, we regard it as likely that two

distinct species are involved.

Tue ADULT

The Strigeid trematode, Apatemon intermedius, was described as Hemi-

stomum intermedium by S. J. Johnston (1904, 109-110), whose material came

from the duodenum of the black swan, Chenopis atrata, Lath., from the Duck-

maloi River, New South Wales, Although the author placed the species under

Hemistomum, he stated that the fusion of the lateral expansions of the body wall

in the posterior region of the fore-body, together with the form of the “clinging

apparatus,” approached the condition occurring in Holostomum. (i.¢., Strigea and

allied genera). Dubois transferred it to Apatemon (1937a, 392; 1937b, 232),

gave a summary (1938, 105) of the short original account, and reproduced one

of Johnston's figures,

Attempts to trace S. J. Johnston’s material in the Technological Museum,

Sydney, where he was at the time Economic Zoologist, and in the Zoology De-

partment of the University of Sydney, where he later became Professor, failed

to Jocate it. Though the Australian Museum received types of most of his later

species of trematodes, his H. intermedium was not included.

* University of Adelaide.

Trans. Roy Soc. §. Aust., 74, (1), March 1951

We have found A, intermedius in five of eleven black swans taken from the

Murray River swamps at Tailem Bend, South Australia, during the summer

months between October 1939 and April 1947; and in one collected at Bow Hilll,

north of Mannum, in May 1950. The worms were obtamed from the duodenum

and, on one occasion, from the proventriculus, Usually only a few were present in

infected birds, but on one occasion, iri October 1947, abundant very young stages,

with adults, were obtained from the duodenum.

Fig, 1-7

Apatemon iniermedius, adult; 1, lateral views the vitellaria. covering the testes

latetally have been omitted, 2, posterior region, ventral, bursa everted. 3, fore-body,

ventral. 4, 5, LHS. hind-hody; fig. ‘9 represents a section more yentral than that

shown in fig. 4. 6, L.V.S., fore-body. 7, oblique L.V-5., showing base of fore-body.

Fig, 2 and 3 to samie scale; 4 and 5; 6 and 7.

Since most adult specimens have the fore-body more ar less bent back on

the dorsal region of the hind-body, the neck occupies an oblique position and

the dorsal and ventral surfaces of the hind-body are of unequal length. In

such cases, whether adult or juvenile, the length of the fore-body has been

taken as the distance between its anterior end and the middle of the neck, just

behind the prominent group of glands lying behind the holdfast apparatus.

The length of the hind-body is the distance between the above-mentioned

point in the neck and the posterior end of the worm (with its bursa re-

tracted). The total length of the trematode is the sum of the two measure-

nients, <All specimens were meastired in glycerine or in cedar wood oil, and

without coverglass or presstire, unless otherwise stated,

The fore-body was usually strongly bent back towards the dorsal part

of the hind-body. Egg-bearing worms were from 3-5 to 5 mm. in length, the

fore-body being 1 to 1-5 mm. long, -9 to 1-25 mm. in maximum diameter,

approximately circular in transverse section, and with its sides not quite

parallel, There is a definite neck constriction, The hind-body is subcylindri-

cal, narrowing somewhat towards each end, and its ventral surface tends to

form a low arch, The posterior extremity is directed slightly dorsally and is

broadly rounded when the genital papilla is withdrawn within the bursa.

The maximum widths of the fore- and hind-body are usually about the

seme, but there is some variation in this respect. The hind-body varied from

2°5 to 3 mm. in length and *75 to 1-5 mm. (usually 1 -— 1-25 mm.) in maxi-

mum breadth. ‘The ratio of the length of the fore- and hind-body was about

1:2°2~2°5, The smallest egg-bearing worm, the dimensions of which have

not been included in the foregoing measurements, was only 2°75 mm. in

length, with a fore-body 1-0 mm. Jong and ‘9 mm, wide, and with a narrow

hind-body 1-73 mn, long and -8 mm. in maximum breadth: the ratio of fore-

to hind-body is thus 1;1'75, S. J. Johnston reported the following lengths:—

entire worm 3:6, fore-hody 0°67, and hind-body 2:93 mm., the ratio thus be-

ing about 1;4°4; but if we apply our method of measurement to his figure 7

(which is X 37), the total length of the specimen figured would be about

2-7 mm., that of its fore-body *76 mm., and that of its hind-body 1-94 mm.,

giving a ratio of 1:2'5 as in our adult material.

The genital papilla, when fully protruded, is a large cone with a rounded

tp, this cone measuring -3 to -5 mm. in length, thus being about one-tenth

the total iength of the worm.

The oral sucker, -15 ~ -22 mm. in diameter, is subterminal: the ventral

sucker is larger, "3 — ‘33 mm. in diameter, and sometimes is stalked, ‘The

latter, when not stalked, reaches almost to the dorsal surface, The rélative

positions of the two suckers is indicated in the figures. The sucker ratio

varies from 1:2 to 2:3, Lying laterally in the region between the two

suckers, and on a level with the oesophagus and part of the pharynx, are the

lateral suckers. When studied in serial sections each is seen to be an ex-

tensive wide depression lined by muscle fibres which pass to other parts of

the fore-body. Unlike true suckers, they do not possess a definite basement

membrane so that their inner boundary is not sharply delimited. They are

obviously the persistent lateral depressions of the tetracotyle. S, J. Johns-

ton referred to (and figured) two groups of very large unicellular glands,

each group opening into a crescentic depression of the ventral body surface.

We have not been able to recognise such gland cells in our material,

The cup within the fore-body is yery extensive, its anterior border reach-

ing usually almost to the posterior end of the anterior sucker. S. J, Johnston

seems to have missed its anterior margin, judging from his remarks and his

figure 8; but his figure 7 indicates the condition more nearly, though we have

not often seen such a markedly petiolate acetabulum as he indicated in fig. 7.

Projecting from the base of the cavity behind the ventral sucker, are two

large complexly folded “clinging plugs” or tribocytic organs. The more pos-

terior may be the longer, and may project slightly through the mouth of the

cup. Both organs may have their margins infolded or even rolled back on

their more basal portions. The anterior of these organs is grooved longi-

any

Fig. 8-15

Apatemon intermedius, T.S. hind-body of adult: 8, at level of ovary, showing caeca

surrounded by vitellaria; ascending uterus ahout to join descending limb. 9, at level

of ovary and coils of oviduct. 10, at level of anterior testis; Laurer’s. canal; oviduct

Passing upwards laterally from testis to occupy dorsal position, 11, at level of

posterior part of anterior testis; ascenditig uterine coils moving itto more ventral

position between testicular lobes. 12, at level of posterior testis, showing its marked

lobulation; two vitelline ducts, reservoir and common vitelline duct. 13, at level of

posterior part of second testis; vesiciila seminalis lying dorsally between testicular

lobes. 14, through hind-body in region of hermaphrodite duct and retracted bursa,

‘15, through posterior region of head, showing bases of holdfast organs.

tudinally and transversely when withdrawn, and its stalk appears to have

a glandular base and core. The musculature of these organs is strongly de-

veloped, the bundles of fibres being large, numerous and deeply staining.

Behind these organs is a very striking group of large unicellular glands.

spherical or pyriform, but the actual openings into the base of the cup were

not recognized. The cytoplasm of the glands contained numerous sinall

vacuoles which may perhaps represent the position of secretory granules in

the living cells, S.J. Johnston did not mention these organs which, in un-

stained worms, appear as a small group of large highly refracting bodies be-

tween the base of the tribocytic apparatiis and the neck of the worm. Dubois

(1938, fig. 45-46), as well as Stunkard, Willey and Rabinowitz (1941, pl. 1,

fig. 6) indicated the presence of similar structures in Apatemon gracilis, The

hind portion of the fore-body is well supplied with longitudinal muscle fibres,

which extend from the walls of the cup and from the base of the tribocytic

apparatus into the bedy wall of the hind-bady,

The oral sucker faces almost ventrally. It is succeeded by a pharynx

"08 — 13 mm. long by -05 - -07 mm. wide, which is directed postero-dorsally.

There is no prepharynx. The oesophagus bends ventrally in the region in

iront of the acetabulum, where it divides into the two crura which pass back,

one on either side of the acetabulum, the two tubes approximating as they pass

throvigh the neck. In the hind-body they lie in the ventral region, belaw the

testes and on either side of the descending uterus. In the most anterior part

of the hind-body, just behind the neck, and even in part of the ovarian region,

they are actually surrounded by the inner vitelline jollicles, but elsewhere they

lie just dorsaily from the netghbouring yolk glands. The crurca terminate

near the posterior end of the worm and lie beside the retracted genital papilla.

The testes are large and are arranged in tandem. They are very deeply

lobed, and in longitudinal and transverse sections may each appear to con-

sist of four or five separate organs, The testes lie dorsally to the vitelline re-

gion, the caeca and the descending uterus, but ventrally to part of the ascend-

ing uterus and the shell glands, The anterior testis is about ‘7 mm, long and

‘6 mm, in dorsoventral diameter; the posterior testis, 5 by ‘6 mm. The tes-

ticular region occupies about 1:2 mm. in length in a worm 4:3 mm. long with

a hind-body 3 mm. in length. This zone is about one quarter of the total

length of the worm. The anterior margin of the anterior testis is distant

from the neck about one-sixth the length of the hind-body, while the pos-

terior end of the hind testis is distant from the end of the worm (with re-

tracted bursa) nearly one half the length of the hind-body. The anterior vasa

efferens arises ventrally and travels back above the descending uterus to join

the posterior vas efferens. immediately behind the second testis. Here it

forms the voluminous, twisted vesicula seminalis which occupies a dorsal

zune behind the testes and above the uterus. Eventually it becomes the vas

deferens which ts joined by the uterus from below, and the wide strongly

folded hermaphrodite duct so formed enters the tissnes of the genital cane.

The latter when retracted lies within the bursa capulatrix whose wide aper-

ture is slightly dorsally directed. As in other species of 4patemon there is no

well-marked bursal sphincter, The cone when fully protruded may measure

“3 to -5 mm. in length,

The spherical ovary is about *2 mm. in diameter and is situated on one

side at about the mid-dorsoventral level, close behind the neck constriction.

Its posterior border may touch the anterior testis, Between the latter organ

and the ovary, and occupying a region on the auti-ovarian side, is the wide

oviduct. The latter arises from the ovary just above the utertts, and then

makes its way dorsally to become arranged in a number of coils in the pos-

rat

terior ovarian fegion, and especially in the region immediately in front of

the anterior testis, some of the coils lying above portions of the latter, It

then comes to oceupy a more ventrolateral position, below the anterior testis

and on one side of the descending uterus, From here it makes its way dors-

ally just laterally from the end of the anterior testis, and in the narrow inter-

testicular tegion,it enters the shell gland and unites with the common yolk

duct, From this point arises the narrow Laurer’'s canal which passes dor-

sally in a curved course to reach the surface aboye the posterior part of the

anterior testis. The ascending uterus becomes thrown into a number of loops

between the lobes of the anterior testis, and makes its way ventrally and for-

wards so as to lie just above the descending uterus and partly amonst the

loops of the oviduct. Inwardly and ventrally from the ovary, the two parts

of the uterus lie side by side, the descending limb being the more ventral,

and in the region between the ovaty and the antetior extremity of the hind-

body, the ascending uterus bends down to continue back as the descending

uterus. The latter occupies 2 median position below the testes and seminal

vesicle and between the intestinal crura, but above the netghbouring vitelline

glands. It eventually enters the hermaphrodite duct midvertrally, while the

vas deferens enters it dorsally and laterally. The hermaphrodite duct, when

the bursa is withdrawn, is strongly contracted, its walls heing thrown into a

great number of closely arranged folds surrounded by loose tissue and muscle

fibres, the whole organ terminating at the genital cone.

The yolk glands are very extensive and occupy a ventral and vetitro-

lateral zone extending from the neck to the posterior end of the hind-body. At

either end of the latter the follicles tend to extend rather more lowards the dorsal

surface than they do elsewhere. As already mentioned, the vitellaria surround

the crura in the pre-ovarian region. The two short main yolk ducts pass inwards

and upwards in the intertesticular zone, the uterus lying between them. The two

ducts soon join to form a small, more or less triangular, yolk teceptacle from

which there issues directly dorsally the tubular common yolk duct. The latter

joins the widened aviduct near the dorsal surface. The shell glands lie between

the posterior lobes of the anterior testis. Jaurer’s canal has already been

mentioned,

An examination of 5. J. Johnston’s figure (pl. 5, fig. 7) indicates that the

fore-bady has been cut nearly sagitally, and the hind-body mainly longitudinally

and horizoritally. As the figure shows the two crura cut Jongitudinally, we would

expect to see @ mass of yolk glands on both sides of the posterior end of the hind-

body, becatise of the relation of the crura to the vitclline region.

Eggs are °072 to ‘09 by °062- -065 mm., showing very little variation in form

and size, most of them being -O87 by °062--065 mm, They were not mentioned

by S. J. Johnston.

A, intermedius seems to be nearest to 4, gracilis ({Rud.) Szidat, as figured

by Dubois (1938, fig. 45-46}, but is differentiated from it by having a larger size;

a more forward position of the testicular region, the ovary, and the anterior end

of the uterus; a much longer hermaphrodite duct; a relatively longer genital cone;

and by the different sizes of the eggs. A. gracilis occurs in Europe as an adult

in ducks; as a cercaria in Bithynia tentaculata, and as a tetracotyle in freshwater

leeches, Herpobdeila and Haemopis (Szidat 1931, 160-172; 1929, 728-730; Neveu-

Lemaire 1936, 248).

Szidat (1931) reported that the larva of 4. gracilis closely resembled, but

was specifically distinct from, Cercaria burti Millet, and gave tabulated measure~

ments of the two larvae (p. 165). The North American hosts of C. burtt were

Planorbis trivolwvis (Miller 1926, 41-44), Lymnaea stagnalis (Miller 1927, 77), and

Lymnaea humilis (Cort and Brooks 1928, 209-210), Willey and Rabinowitz

(1938) stated that C. burti had its metacercarial stage in leeches (Herpobdella

sp.) and tentatively assigned the adult (obtained from ducks after experimental |

feeding of cysts) to Apatemon sphaerocephalus. Olivier (1940) listed C, burti

as the larva of A. globiceps, giving as reference Willey and Rabinowitz’s paper

of 1938; but in 1941, with Cort and Brackett (Cort, Olivier and Brackett 1941,

440) he listed C. burti as the larva of A. sphaerocephalus, A, globiceps was a

renaming by Dubois (1937, 392; 1938, 100) of A, sphaerocephalus (Brandes)

Szidat, nec Westrumb, the latter’s species being a Strigea. Stunkard, Willey and

Rabinowitz (1941) regarded C, burti as the larva of A. gracilis, with C. pseudo-

burti Rankin 1939 as a synonym.

Fig. 16-23

Apatemon intermedius, young stages showing development of holdfasts and cup.

shows developing genitalia. 23 shows developing vitellaria.

Fig. 16-22 Drawn to same scale.

It seems to us so surprising that a furcocercaria should make use of two

such widely separated types of mollusc as operculate (Bithynia) and pulmonate

(Lymnaga and Planorbis) gastropods, that we are of the opinion that Szidat, on

the one hand, and Stunkard, Willey and Rabinowitz on ihe other, were working

with different species of the genus. The latter authors gave their reasons in a

discussion in which they mentioned differences in the adults as recorded by them-

selves and by Debois, as well as differences in the life histories, such as the host

snails chosen by the American and European forms, and the differences in time

taken for the development of the tetracotyle, although they suggested a possible

explanation of the latter,

LakvaL STAGES In GASTROPODS

In 1947, Johnston and Beckwith gave an account of Cercaria lessoni, an

Apatemon cercaria from Planorbis isingi, Lymnaea lessoni and Simlimnea sub-

aguatitis, atid mentioned that Apatemnon intermedius had been described from

the black swan, a common inhabitant of the Murray swamps. It has now been

shown experimentally that Cercaria fessoni is the larval form of Apatemon

intermedius,

On 10 May 1947 Miss Beckwith, our former colleague, placed a number of

Lymmoes lessont and Planorbis tsingt in contact with eggs of Echinoparyphium

ellist (Johnston and Ange! 1949) and of Apatemon intermedius. Of eleven

laboratory-hred Lymnaeae none became infected with Apatemon intermedius, but

seven were infected with Cercaria Echinoparyphii-ellisi, The twelve Planorbis

used were not laboratory raised, but had not been observed giving off cercariae

since they had been brought to the laboratory from the Tailem Bend swamps,

and were thus. classed as “apparently uninfected,” On dissection later four were

negative, two were found to harbour other infections, while six contained aporo-

cysts which were thought to be probably those of Cercaria lessoni, and which in

one case contained immature cercariae of this species when dissected 110 days

after exposure to the eggs, The present authors repeated this experiment in the

summer months two and a half years later. On 29 October 1947 eggs from the

duodenal contents of a black swan (which contained adult Echinoparyphinm

ellisi and Apatemon intermedius) were put in a small aquarium (A) with labora-

tory raised Lymnaea fessoni and Planarbis isingi, A number of the eggs were

kept in a small dish and were examined daily. On 1 December 1947 the

Apaiemon eggs began to hatch, and the snails from (A) were removed to an

uninfected tank (B); at various times from 2] days afterwards three Lymnaeae

died, and proved on dissection to be uninfected; a fourth gave cercariae of F. allist

79 days atter the snails were exposed to the eggs. Of four Planorbis, two were

uninfected and two produced Cercaria lessoni when first tested 36 days after the

miracidia had hatched, On the day when miracidia first appeared, eight Lymnaeae

were put in the infected tank A; and on the following day six Lymmaeae weré

added. Four of the fourteen were disintegrated when found, but the remaining

ten which died from 19 to 86 days afterwards, were not infected, However, six

Planorbis were added to tank A on the second day, and 35 days afterwards, when

they were first tsolated, two of them gave off Cerearia lessom; a week later a

third produced cercariac. Of the remainder, two were uninfected and one was

disintegrated when found 41 days after the exposure.

On the same date as that on which eggs were collected from the duodenal

contents of the swan, a number of adult 4patemon intermedivs were put in water

in a stall dish, arid the eggs which they emitted were placed in a tank with six

Lymnacae and six Planorbis. None of the former hecame infected, and unfor-

tihately unly one of the Planorbis survived, to give a negative result on dissection,

Without this last experiment one might have supposed that the failure of

the Lymnacae to become infected experimentally with Apatemon was due perhaps

to an immunity conferred by a previous infection with Echinoparyphium ellisi,

the eges of which hatched before those of Apateman intermedius, However, in

the previously mentioned experiments, a number of Lymmaeae which escaped

infection with Echinoparyphium ellisi, also escaped a later infection with

Apatemon intermedius, and in the last-mentioned experiment, when there was no

contamination of the tank with eggs of Echinoparyphium ellisi, six Lymnaeae

resisted infection with Apateman, It must be concluded, therefore, that Cercaria

lessoni, as described from Pianorbis isingi, Lymnaea lessoni and Simlannea sub-

aquatilis exists in at least two strains, and that the strain which infects Planorbis

does not readily infect Lymnaea, Strlimnea subaquatilis was not used in the

experiments, as this snail is not often found, and we have not yet reared it under

laboratory conditions.

Cort, McMullen and Brackett (1937), and Cort, Olivier and McMullen

(1941) dealt at some length with the problem of multiple infestations of snails

by cercariae. In 1937 Cort and his fellow-workers, in a historical survey of

multiple infestations, showed that records of double infections of echinostome

cercariae with other forms were comparatively uncommon. From their own

observations with Stagnicola emarginate anguleta, they thought it probable that

some immunity or antagonism existed between cercuriae of Echinostomum revolu-

two and some other species of cercariae (not of echinostornes), since they never

appeared in double infections. In 1941 Cort et al., working with cercarial infec-

tions of Phryso parkert, suggested that some such condition prevented double

infections of the cercaria of Echinoparvphium recurvatum with the schistosome,

C. physellae Talbot 1936, and the strigeid, C. physae Cort and Brooks 1928, since

each of the combinations, according ta chance, should have occurred much more

often than it actually did,

From December 1937 to September 1950 we have identified only six double

infections in 7,087 Lymnaea lessoni examined. Three of these involved echino-

stomes, one of which was coupled with Cercaria lessont; a fourth coupled the

latter form with C, Plagiorchis-jaenschi Johnston and Angel 1950. |

From May 1946 (the last date for which percentage infections of C. lessoni

were recorded by Johnston and Beckwith) to September 1950, C, lessen? has been

identified in 57 of 1,991 Planorbis isingi, this total comprising 38 of 1,380 from

Tailem Bend, none of 417 from Wood's Flat, and 19 of 194 from Bow Hill.

No Lymneea lessont have been found in the Tailem Bend swamps in this period,

but four of 133 from Wood's Flat and one of 1,779 from Bow Hill, making a

total of five of 1,912, have been found infected with Cercaria lessont. Combining

these figures with those given previously shows that Cercura lessoni has been

observed in 106 of 5,845 Planorbis ising: (1°8%,) and in 117 of 5,648 Lymnaea

lessoni (294,) from December 1937 to September 1950.

MikaAcibiom

Twenty-two days after they were Isid (October-November 1947) some eggs

showed eye spots; ten days later motile miracidia were present; by the next day

all had hatched. The period required for hatching in late spring was thus about

33 days. The miracidia were examined in serum diluted one-half, which had the

effect of inymobilizing them for examination, but which slowly killed them. The

head end (fiz. 26) was more distorted by the serum than was the rest of the body,

as the actively swimming miracidium appeared quite sharply pointed, The eye

spots are kidney-shaped and very dark. On one side, latera-posteriorly ta the eye

ot, was a pair of Alate cells, with a collecting tube which extended nearly to

the posterior end, where another flame cell was situated.

METACERCARTA

Stunkard, Willey and Rabinowitz (1941) reported of Cercaria burti that

the larvae grew and developed in the leech and did not encyst until 30 to 42 days,

and that none had encysted at 23 days. This is not the case with Apatemon inter-

medius, 23-day-old metacercariae of which are enclosed in a thick cyst wall and

can only be excysted mechanically with great difficulty, An average of ten such

cysts measured 265 by 206, the inner cavity being 205 by 176. Johnston and

Beckwith (1947) reported cysts of two sizes from leeches which had been

exposed to cercariae 7 and 13 wecks betore they were killed, In the smaller

cysts (presumably seven weeks old) the cavity measured 205 by 180», while the

meastirement including the cyst wall, was 295 by 246m. From these measure-

ments it would seem that from 23 days to seven weeks of inetacercarial develop-

ment ificrease in size is in the thickness of the cyst wall, However, the size of

the cyst may not necessarily be dependent only on age, as is indicated by a single

cyst which was obtained from a leech 23 days after infection, the measurements

(338 by 300 p, with the cavity 270 by 218 «) being substantially larger than those

given for the previous series,

{t is perhaps of interest to note that Stunkard et al, were unable to infect

with C. burti three Placobdella parasitica and two P. rugosa (belonging to the

Rhynehobdellida), whereas Herpobdella (Athynchobdellida) was readily infected;

we were not successful in attempts to infect three Limnobdella australis

(Arhynchobellida) with C. Apatemon imtermedius, which encysted readily in

Glossiphonia (Rhynchobdellida}. It would seem that Apatemon cercariae are

not only selective in their choice of leech host, but that, the type of leech differs

for different species of the genus.

Comparison of fig. 28 with Stunkard’s fig. 3 shows that the reserve excretory

systems of the two forms as seen at 23 days metacercarial development is sub-

stantially the same; we did not observe the terminal vesicles or any calcareous

concretions associated with them, but the system was packed with small excretory

granules. In our form the median anterior canal as well as the posterior one,

joined the transverse canal which lies just posterior to the ventral sucker. John-

ston and Beckwith (1947) gave figures showing the commencement of the

development of the secondary excretory system in the cercaria,

A series of six 23-day-old metacercariae, stained and mounted, measured

from 158 by 113p to 225 by 165», the measurements being taken across the

greatest width, The metacercariae had attained much the same stage of develop-

ment as that shown by Stunkard et al. in their fig. 2.

In the ofiginal account of Cercaria Jessoni, the figures of older metacercariae

freed from their cysts indicate length about -33 mm,, maximum breadth -26, fore-

body +25 by -26, hind-body 08 by +13 (at junction with fore-body) for the worm

shown in fig, 7 (a ventral view), and -42 by ‘29 for that indicated in fig. 9 (a

jateral view),

Juvenite Sraces FounD In tHE BLACK Swan

As mentioned earlier, we found numerous juvenile tetracotyliform stages

along with adults in the duodenum of a black swan taken at Tailem Bend in

October 1947. These young worms were of different sizes and in various stages

of development, On three occasions we have found in the stomach of black

swans from the same locality Giossiphonia leeches, and one of them was heavily

infected with the thick-walled cysts of Apatemon, distributed in its blood system

from the posterior sucker almost to the anterior end. We have found natural

infections in two species of Glossiphonia, one of them larger. thicker, more

leathery and papillose, the other smaller, more slender and semi-transparent, both

kinds from Tailem Bend swamps.

The youngest stage found in the swan was a tetracotyle, -11 by -10 mm.,

with the anterior two-thirds more or less spherical and the posterior third broadly

rounded; while the cup and holdfast organs were present, Another (fig. 16),

with the hind-body merely represented, measured +15 by +10 mm., its oral sucker

was 025 by ‘03 mm. and the acetabulum -03 mm. in diameter, and the cup and

holdfast organs were well developed. Another was nearly spherical, -145 by

“145 mm,, with the hind-body scarcely recognisable, but it possessed a well

developed cup and small holdfast organs. Measurements of other very juvenile

worms were *16 mm. long by ‘10, with a very small post-body, with oral sucker

"03 by ‘02 mm., and acetabulum “05 mm. diameter; -20 by +10 mm., with well

defined post-body (fig. 17) and with suckers -025 and ‘04 mm, diameter respec-

tively ; -24 by -13 mm., suckers -03 and ‘05 mm. diameter; -36 by *17 mm., suckers

“055 and -08 mm.; ‘43 by ‘33 mm.; °47 by -25 mm., suckers -06 and ‘08 mm.

In fonger worms the hind-body becomes relatively more pronounced, but is much

narrower than the fore-body—total length °55 mm., forebody -40 by -30, hind-

body *15 by ‘2, sex organs recognisable, oral sucker ‘08 by ‘07, acetabulum

Fig. 24-28 .

Apatemon intermedius: 24, 25, T.S. anterior part of fore-body, showing lateral

suckers; 24 lies in front of acetabulum; 25 shows Stalked acetabulum in section

26, miracidium; 27, metacercaria (tetracotyle) from 23 day-old cyst in Glossiphonia;

stained preparation showing holdfasts, 28, metacercaria (tetracotyle) from 23 day-old

cyst in Glossiphonia; drawn from living larva; shows excretory system. Fig. 24-25 to

to same scale; 26, 28 sketches; 27, to adjacent scale.

“12 mm. diameter; -62, fore-body -47 by *34, hind-body -15 by °25, genital

organs recognisable, but closely crowded; -71, fore-body -46 by ‘38, hind-body

*25 by +26 mm., with genital organs as in the preceding; 1-0, fore-body, °55 by

“5, hind-body -46 by °27, sex organs as in the preceding two worms, In a

specimen, 1-52 mm. long, the fore-body was ‘72 by °52, and the fusiform hind-

body ‘80 by ‘37, oral sucker "12, acetabulum -16 mm; vitelline follicles were

present as minute scattered groups, and the gonads were no longer crowded, all

the organs of the adult stage being readily recognisable (fig. 23). We have

already noted that the smallest ovigerous worm was 2°75 mm. long. The youngest

specimen of A. gracilis obtained by Szidat (1929, 145) from a duck, twenty

hours after he had fed it with infected leeches, was (according to his figure 4)

-36 mm. long and about *26 mm, in maximum width, and the gonads were already

distinguishable.

Recatise of the presumed loss of S. J. Johnston’s type material, we have

designated one of our specimens as the substitute type and have deposited it,

along with others, in the South Australian Museum, Adelaide.

We desire to acknowledge generous assistance, in our field work from

Messrs. G, G. and Bryce Jaensch of Tailem Bend, and Mr. J. Brook of Bow Hill,

lower Murray River; and from Mrs. J. Hardy (née A. C, Beckwith), a former

colleague, We are also indebted to the Commoriwealth Research Grant to the

University of Adelaide for the opportunity to carry out the investigation.

LITERATURE

Cort, W. W., and Brooxs, S. T, 1928 Studies on the Holostome cercariae from

Douglas Lake, Michigan. Tr. Amer. Mier. Soc., 47, 179-221

Cort, W. W., McMutien, D. B., and Brackett, §. 1937 Ecological studies

on the cercariae in Stagnicola emarginata angulata (Sowerby) in the

Douglas Lake region, Michigan, Jour. Parasit., 23, 504-532

Cort, W. W., Otrvier, L., and Brackett, S. 1941, The relation of Physid

and Planorbid snails to the life cycle of the Strigeid trematode, Coty-

lurus flabelliformis (Faust 1917). Jour. Parasit. 27, 437-448

Cour, W. W., Otivier, L., and McMuuten, D. B. 1941 Larval trematode

infection in juveniles and adults of Physa parkeri Currier. Jour.

Parasit., 27, 123-141

Dusors, G. 1937a Sur quelques Strigeides. Rev. Suisse Zool., 44, 391-396

Dusors, G. 1937b Etude de quelques Strigeides d’Australie, etc. Ann. Parasit.,

15, 231-247, 333-353

Dusors, G. 1938 Monographie des Strigeida (Trematoda). Mem. Soc. Neu-

chat. Sci. Nat., 6, 535 pp.

Joxunston, S. J, 1904 Contributions to a knowledge of Australian entozoa,*

No. ili. On some species of Holostomidae from Australian birds. Prac.

Linn. Soc. N.S.W., 1904, 108-116

Jounston, T. H., and Ancer, L. M. 1949. The life cycle of the trematode

Echinoparyphium ellisi, from the black swan, Rec. S. Aust, Mus.,

9, 247-254

Jonnston, T. H., and Ancer, L. M. 1950, The hfe history of Plagiorchis

jaenschi, a new trematode from the Australian water rat. Trans. Ray.

Soc, S. Aust., 74, 49-58

Jounston, T. H., and BeckwitH, A. C. 1947 Larval trematodes from Aws-

tralian freshwater molluscs. Part XI Rec. S. Aust. Mus., 8 (4);

563-583

Mirter, H, M. 1923 Notes on some furcocercous larval trematodes. Jour,

Parasit,, 10, 35-46

Mitier, H. M. 1926 Comparative studies on furcocercous cercariae, Ilinois

Biol. Monogr., 10, (3), 112 pp.

Mituer, H. M, 1927 Furcocercous larval trematodes from San Juan Island,

Washington, Parasitol,, 19, 61-83

Neveu-Lemairz, M. 1936 Traité d’ helminthologie médicale et vétérinaire

Ourvier, L, 1940 Life history studies on two Strigeid trematodes of the

Douglas Lake region, Michigan. Jour, Parasit., 26, 447-477

RanxIn, J. S., Jnr. 1939 Cercaria pseudoburti n. sp. A Strigeid cercaria from

Western Massachusetts. Jour. Parasit., 25, 87-91 '

StunxKarp, H. W., Witiey, C. H., and Rapinowirz, Y. 1941 Cercaria burti

Miller 1923, a larval stage of Apatemon gracilis (Rudolphi 1819)

Szidat 1928. Tr. Amer. Micr. Soc., 60, 485-497

Sziwat, L. 1929 Beitrage zur Entwicklungsgeschichte der Holostomiden, III.,

etc. Zool. Anz., 86, 133-149

Szipat, L. 1931 Beitrage zur Entwicklungsgeschichte der Holostomiden, IV,

etc. Z. £, Parasitenk., 3, 160-172

Witiey, C. H., and Rasinowitz, Y. 1938 The development of Cercaria burti

Miller 1923 in leeches and ducks. Jour. Parasit., 24, Suppl. 30-31

REFERENCES TO LETTERING

ac, acetabulum; ah, anterior holdfast organ; am, anterior margin of cup in fore-body;

ay, anterior vas efferens; b, bursa; cc, cavity of cup in fore-body; cv, common vitelline

duct; e, egg; fb, fore-body; ge, genital cone; h, holdfast organ; hb, hind-body; hd,

hermaphrodite duct; i, intestine; Ic, Laurer’s canal; 1s, lateral scker; m, muscle;

od, oviduct; oe, oesophagus; os, oral sucker; ov, ovary: p, pharynx; ph, posterior

holdfast organ; phg, post-holdfast glands; sg, shell glands; tl, t2, anterior and posterior

testes; ‘u, titerus; ua, ascending limb of uterus; ud, descending limb of uterus; vd, vas

deferens; vi, vitelline follicles; vr, vitelline reservoir; vs, vesicula seminalis; vtd,

vitelline duct.

A RECONNAISSANCE SURVEY OF THE SOILS AND VEGETATION OF

THE HUNDREDS OF TATIARA, WIRREGA, AND STIRLING OF THE

COUNTY BUCKINGHAM

BY R. L. SPECHT

Summary

This paper deals with the woodland communities of the Bordertown and Keith districts in the Upper

South-East of South Australia. These fertile communities lie within the vegetation communities of

the “Deserts” and show a sharp line of demarcation from them.

A RECONNAISSANCE SURVEY OF THE SOILS AND VEGETATION

OF THE HUNDREDS OF TATIARA, WIRREGA AND STIRLING OF

COUNTY BUCKINGHAM.

By R. L. Specut *

[Read 9 November 1950]

CONTENTS

I. SumMary tsi. ont tare data aa 45

2, Intropuction ,... _ sess sis boas

3, Locarity

4. CLIMATE .... oo | ”

6, PEpeLocy este wie sb

A, Grey soils eg heavy texture wise

B. Red-brown earths ..

§. Complex of grey mee red soils ‘af heavy fepfuare

L Solonized woodland soils

E. Rendzinas base sie ani

F. Red mallee soils .... i have Set

G. Meadow podsols v.00 sus snte tae

H. Stirling sandy clay loam ry, his

i. Laffer sand—woodland phase .... oon foi

jy. THE VEGETATION ».. wis aus aise

A. Autecology of the dominant: species

(1) Casuarina Inehmanni ia Sie ire

(2) £, calcicultrix ais oe asis one

(3) EF. leucosxylon Ae tO ee

(4) E. largiflorens hey ea _ ses

(5) BE. camaldulensis nc eas

(6) Melaleuca pubescens aver ar oe

(7) E. fasciculosa tad aac aaah

(8) Savannah woodland “foriistion wney “sad

B. Classification of the plant comrunities

(1) Casuarina luehmanni association 00 4

(2) E. calcicultrix association .... us

(3) E. leucoxylon association .... tig west

(4) . camaldulensis association are

(5) £. largiflorens association .... west. sit

(6) Melaleuca pubescens association... sa

(7) “Desert’* edaphic complex ....

(a) E. barteri association

“1 err) rd

Pvery seer

verre aoe

{b) £. fasciculosa — Xanthorrhoea semiplana association

(d) E, behriana = E. anceps association

(e) Xanthorrhoea semiplana - Banksia ornata association

(£) E. incrassata — heath asssociation

(g) E. diversifalia association

(8) &. leucorylon—E, fasciculosa ecotone ....

8 ACKNOWLEDGMENTS 4. Ve toe

9. REFERENCES vase rss ses e oe

10. AprennIx—A comparative floristic list of the major vegetation ehinmushities

bere sere

* Agronomy Department, Waite Agricultural Research Institute, and

Botany Department, Adelaide University.

wat Roy Soc, S. Aust., 74, (2), March 1951

101

102

104

SUMMARY

This paper deals with the woodland communities of the Bordertown and

Keith districts in the Upper South-East of South Australia, These fertile com-

miinities lie within the vegetation communities of the “Deserts” and show a sharp

line of demarcation from them.

The climate, soils and vegetation have been studied, and attempts made to

correlate the dominant trees and associations with the factors of the environment.

The climate is typical of the Mediterranean region and shows a range in

rainfall from 18 to over 20 inches per annum,

Grey soils of heavy texture, a complex of red and grey soils of heavy texture,

red-brown earths, solonized woodland soils, meadow podsols, rendzinas, ted

mallee soils and soils with affinities with the Laffer sand have been observed and

mapped.

Peng distribution of the Casuarina luehmanni, Encalyptus calcicultrix,

E. leucoxylon, E. comaldulensis, E. largiflorens and Melaleuca pubescens savannah

woodland associations within the area has been mapped and investigated in rela-

tion to these factors of the environment,

A brief resume of the vegetation of the adjacent “Deserts” is added for

contrast, rs

INTRODUCTION

This reconnaissance survey of the soils and vegetation of portion of the

Uppet South-East of South Austra‘ia is intended as a basis for a pasture str-

vey being carried out by the Waite Agricultural Research Institute, and

financed by the Australian Wool Board.

This survey is primarily concerned with the woodland communities of the

Keith (Hundred of Stirling) and Bordertown (Hundreds of Wirrega and

Tatiara) districts in the Upper South East of South Australia. These fertile

communities lie within the mallee-broombush, heath and mallee-heath com-

munities of the “Deserts” and show a sharp line of demarcation from them.

The possible relationships between the woodland communities and those of

the “Deserts” have been investigated.

The survey has been made by examining the distribution of the soils

and vegetation along all the passable surveyed roads of the area. Extrapola-

tion of the boundaries was found unnecessary im most cases, for the roads

were relatively close together. However, as most of the surveyed roads of

the “Deserts” were impassable, the vegetation there has been correlated and

mapped from aerial photographs.

LOCALITY

The Bordertown district, defined by the Hundreds of Tatiara and Wir-

rega of County Buckingham, South Australia, is the westerly extension of

the rich Victorian Wimmera district, and therefore, especially on its eastern

extremity, shows matked similarities to the latter. It lies between the so-

called Big and Little “Deserts” of the north and south respectively and the

Ninety-Mile “Desert” in the west. These “Deserts” are complicated forma-

tians of sand dunes formed during the Arid Period of Recent Times (8) and

are clothed in a scrubby vegetation of stringybark, pink gum, mallee-

heath, heath and mallee-broombush,

The Hundred of Tatiara is drained by two main streams, the Tatiara

Creek in the north, and the Nalang Creek in the south. From a south-

easterly direction, shallow watercourses enter both these streams which flow

in a general westerly direction, The country between the “Deserts” has thus

developed a gently undulating topography. As the fall in the level of the

land towards the west is so gradual, the streams become less definite and

finally end in a series: of shallow swamps on the eastern side of the Hundred

of Wirrega.

ope

Naracoor mda" ~

23 >

zl >

25°

26°

{) :

Rainfall Map al \ 31°

of the Sear 3r°

South East of South Australia \ wheetie® 435

Vote

Isohyets 20° Rain gauge @ 28

27"

——

Area Surveyed

° io 620035 ao Somfs.

ees

Fig. 1

The drainage of the Hundred of Wirrega is poor, most of the excess

water finding its way into numerous swampy hollows. Towards the west,

however, the water percolates rapidly through the underlying rocks.

Several ridges of consolidated dune limestone overlain with travertine

Emestone occur in the Hundred of Wirrega. Three of these, the Cannonball

Ridge and the Changwa Ridges, run ina N.N.W., direction, while the others,

the Kongal Ridges, which occur further to the west, run almost at right

angles tc the latter.

The woodland area, which occurs around Keith in the Hundred of Stir-

ling, can be regarded as an extensive expression of a blue gum-pink eum flat.

These flats oceur scattered throughout the “Deserts” wherever low-lying,

wetter pockets of soil have been developed. An area of shallow calecimorphic

soils allied to those found to the west of the Hundred of Wirrega occurs at

the lower-lying centre of this woodland area.

Figure 1 shows the position of the surveyed hundreds in relation ta the

South East as a whole.

CLIMATE

The climate is typical of the Mediterranean Region with marked winter

rains and summer droughts. ‘This is indicated in Table I which shows the

mean monthly rainfall, temperature and relative humidity of Serviceton over

a period of 34 years, its average annual rainiall being 19°01 inches. The

rainfall map (Figure 1) for the South East of South Australia indicates a

gradual increase in rainfall from the north-eastern to the south-western

corner of the Bordertown district. This small variation in rainfall, acting with

the variable soils of the district, is critical for the distribution of the

Eucalyptus species prevalent over the area,

The Hundred of Stirling lies in a slightly drier area with Keith town-

ship recording an average rainfall of 17-87 inches over a petiod of 36 years.

Although no temperature or humidity records are available within these

districts they have been recorded at Serviceton, a Victorian town just over

the border, for several years.

Taste I

Yr. J. FO M A M FD Jf. A S&S O& N. DD, Mean Annual

Mean rel. humidity - 15 64 #65 69 JR 83 ES 89 84 79 FM 71 FW 76%

Mean monthly temp. 24 §=669,4 68.6 65.6 64.4 54.3 49.1 48.3 49.8 53.4 57.9 65.0 66.8 58.8° F.

Mean monthly rain - 34 52 7i 77 128 225 245 236 236 226 176 lI? LIZ 19,01 ans.

From these records influential rainfall (P/E greater than 1/3), is found

to occur on the average for 74 months of the year, i.e., from just before April

until the beginning of November, Trumble (19) has extrapolated these and

other records and has shown that Bordertown and Keith have mean influen-

tial rainfaJl seasons of 7-5 months and 6°9 months respectively.

Trumble has also shown that drought years with less than five months

continucus rainfall occur with a frequency of 14% and 22% for Bordertown

end Keith respectively.

GEOLOGY

Although very few rocks are exposed, the area seems to be underlain

with Miocene limestone. Orecasional outcrops of granite occur through the

“Desert.“ A similar owtcrop occurs in Section 297 of the Hundred of Wir-

rega where it has apparently served as a basis for a small, consolidated dune

range, Several ridges of consolidated calcareous sandstone, representing

former dunes, occur in the Hundred of Wirrega. As mentioned above, these

ridges are in two sets at right angles to each other. Travertine limestone

appears to overlie the Miocene limestone where it approaches tlre surface on

the rises.

These ridges apparently represent portion of the original coastline be-

fore the fluctuations in the sea level in the Pleistocene Period. The irregular

directions of these dunes, when considered in relation to the dunes occurring

tu the north and south, may indicate the position of a complex of dunes

around the mouth of a river (private communication from P. S. Hossfeld).

PEDOLOGY

The soils of the Bordertown district are dependent to a Jarge extent upon

the topography with its associated drainage relationships. They are all de-

yeloped from similar parent material, viz. limestone. However, on account

of their variability with every change in topography, great difficulty was ob-

tained in obtaining a picture of the soil groups. The soils of the woodland

communities can be summarised as follows :—

Limestone at limestone near

depth ; surface

Solonized woodland

soil

Good drainage red-brown earths <=—=————= red mallee soils

Medium drainage Complex of grey | . }

; and red soils of ———— ies

-heavy texture Sons

(crabholey) |

Poor drainage grey soils of

heavy texture ——— rendzinas

(crabholey) if

meadow

podsol

The soils of the “Deserts” owe their origin to the encroachment of sand

from the series of dunes left behind as the sea retrealed during the Pleisto-

cene Period. With the onset of the Arid Period (Crocker 8) during Recent

Times the vegetation was largely destroyed, thus allowing sand drift to occur

under the impetiis of the prevailing winds, A series of seif dunes with inter-

vening sand flats encroached over the former soils. It would appear that

numerous vegetated swamps receiving the drainage from the east existed in

the Hundred of Wirrega during the Arid Period and this served as a barrier

to sand drift betwéen the Big and Little “Deserts,” The complex of shallow

rendzina and red mallee soils of the area offers support to this theory, The

relationships of these low-lying shallow soils to the surrounding country in-

dicates a sitnilar set-up to that which occurs in County Cardwell at the pre-

sent day. Here low-lying swampy soils receive the drainage of the Lower

South East. A similar swampy area, indicated by identical soils, probably

occurred at Keith,

With the release of the pressure of the Arid Period, vegetation recolo-

nised the “Deserts.” Through the solonizing effects of cyclic salt, the re-

maining finer fractions of the sands and the original soils were leached to

form the soils as we know them today,

The soils of the “Deserts” support distinctive vegetation. The Little “Desert”

to the south of the Bordertown district is composed of deep podsolised sands

supporting a stunted Eucalyptus baxteri dry sclerophyll vegetation, Small areas :

of this soil occur throughout the woodland soils of the Bordertown district, and

north into the Big “Desert.” The Ninety-Mile and Big “Deserts” exhibit a

complex of soils supporting heath, mallee-heath and mallee-broombush vegetation,

Of these, only the mallee-broombush soil (see profile fig. 7) occurs in the Hun-

dreds of Tatiara and Wirrega. This extends to the south of the Bordertown

district between Swede’s Flat and the woodland soils of the Hundred of Wirrega.

These soils are discussed by Coaldrake in an ecological survey of the Buckingham

suite of the Ninety-Mile Plain (6).

QL AAS LS

yet Aree ele f.

7, Cp '

eMareccorte

To the west of Keith the soils agree with those described by Taylor in a

“Soil Survey of the Hundreds of Laffer and Willalooka” (17). In the Hundred

of Stirling the normal and shallow phases of the Willalooka sand occur near the

Hundred of Willalooka. Towards the Hundred of Laffer, the Laffer sands sup-

porting heath and woodland vegetation predominate. The surface sand of the

woodland phase (Eucalyptus fasciculosa — Xanthorrhoea semiplana) becomes pro-

gressively heavier until it grades into the complex of shallow rendzina and red

_ mallee soils near Keith township. These latter soils support a blue gum (Exucalyp-

tus leucoxylon) savannah woodland which gradually grades into the Eucalyptus

fasciculosa—Xanthorrhoea semiplana association. ‘The transition vegetation is

allied to that which occurs at Tintinara and in the numerous “biue-gum flats”

which occur in the Bangham Scrub of the Little “Desert.” All these soils have

been solonized to varying degrees tinder the influence of cyclic salt,

Figure 2 shows the relationship of the soils of the woodland communi-

ties to those of the “Deserts,”

An account of the soils associated with the woodland communities. of the

area is given below.

A. GREY SOILS OF HEAVY TEXTURE

In the Hundred of Tatiara, a grey soil of heavy texture is developed from

the limestone wherever the area is poorly drained. Such sites are found on

the relatively level surface between the watercourses and in the watetcourses

themselves (see Fig. 3 (1) ). These soils are related to the Russian group

Sierozerms (14 and 15).

Uniform calcareous clay of pH over 8 continues from 4 to over 6 feet,

The soils are “self-mulching,” on drying breaking spontaneously into frag-

ments.

On account of their property of great expansion on wetting and contrac-

tion and cracking on drying the soils exhibit marked crabholey (gilgai or

melon hole) structures some of which are more than 12. feet in diameter.

Leeper (12) suggests that “when the soil dries and cracks in summer, pieces

of the surface fall down the cracks, adding to the bulk of material below.

When this becomes wet again, it swells, and so exerts additional pressure

upwards and sideways. The pressure is relieved at the point of weakness ta

form a puff. The pattern of the points or lines of weakness determines the

final pattern of the puff-crabhoie system.”

The features of the soil are characteristic of the poor drainage condi-

tions. But, although these soils are very wet during the winter, they rapidly

dry out and crack as soon as the warm weather appears. The growing sea-

son finishes rather abruptly on the puffs and usually slightly before the other

suils of the district, The crabholes, however, remain moist for a considerably

longer period. These microclimates are conducive to a modification of the

ground flora between puff and crabhole. The characteristic dominant of the

vegetation of this soil is Casuarina luehmannt (the bull oak) with Eucalyptus

largiflorens (box) confined to watercourses which show the same soil formation.

Profiles from two typical localities are given below :-—

Section 270, Hundred of Tatiara

Purr CRABHOLE

0-5’ Dark prey nutty clay 0-6” Light-grey fine clay

5—” Yellow-brown clay plus lime 6-26" Light-grey fine clay plus lime

48” Continuing 26-38” Yellow-brown and light-grey

mottled clay plus lime

38’— -Yellow-brown clay plus lime

48” Continuing

Section 260, Hundred of Tatiara

Purr CRABHOLE

0-10” me ea ee clay with some 0-14” Grey clay with slight lime

14-36” Grey-yellow-brown clay with

10-24” Yellea-prey brown clay with lime

lime 36’— Yellow-brown clay with lime

24° = Yellow-brown clay with lime increasing with depth

45” Continuing 45” Continuing

It will be noted that subsequent to the swelling of the calcareous clay

cn wetting and the formation of the puffs, there has been erosion of the sur-

face layer of the puffs into crabholes which possess a sturface horizon much

finer in texture than the puffs.

Analyses show that the surface soil of the puffs has a pH of over 8:0

while that of the crabholes is around 7-0. With depth the pH may increase

to over 9°0, Sodium chloride which is in low concentration in the surface

soil (0'018-0-045%) increases rapidly with depth (see Table 2). The con-

centration is by no means critical. Total soluble salts show a corresponding

increase with depth. P,O, is relatively high—O-022% in the surface soil,

The puff-crabhole tends to be “ironed out” by repeated cultivation thus

creating a more uniform environment for crop or pasture.

These grey soils extend into the Victorian Wimmera and occur around

Frances in the Lower South East (see Figure 2).

Millikan (13) has demonstrated an improvement in the yield of wheat on

the application of 7 Ib. zinc sulphate per acre with the superphosphate on

similar soil in Victoria.

The topographical relationships between the sray soil of heavy texture and the rsd brown earth To

1m ira

()

Y Cau. tushmanni = PE, caleicultriz Te. largifforens

Grey soll of heavy Uscture

(e)

a het he a

Complex of red and grey soils of Ragy teature

(9) :

Te it alee ee ag eh

afey soil

. He,

Fig 3 c: erathele

Fig. 3

B. RED-BROWN EARTHS

At the other extreme of drainage conditions such as oceur on the slopes

and rises in the vicinity of watercourses (see Fig. 3 (1) ), the parent lime-

stone has developed a red-brown earth with a profile typical of that given

below :—

Between Section 5 and 6, Hundred of Tatiara

0-6” Grey-red-brown sandy loam with ironstone buckshot

6-24” Red-brown nutty clay

24”— = Yellow-white clay with much limestone

28” «Continuing

The pH increases from 6-94 to 9:22 with depth. The good drainage con-

ditions have allowed the clay and lime to be leached out of the upper horizons

of the profile whereas the poor drainage conditions where the grey soils of

heavy texture occur do not allow much leaching.

The presence of ironstone buckshot is characteristic of these soils and

probably imparts the pinkish colour to the sandy loam or sandy clay loam

of the A horizon. The ironstone is a remnant of the dissection of the mas-

sive laterite of a previous lateritic podsol which presumably covered a large

portion of the country during the pluvial Plio-Pleistocene. How it came to

be mainly confined to these and intermediate soils and rarely found in abun-

dance in the grey soils of heavy texture is puzzling. Considering the small

size of the ironstone, dissection of the country to form its drainage system

may have caused the pebbles to drift laterally from the surface of the

peneplain into these soils.

The presence of an A horizon of sandy loam or sandy clay loam texture

allows much of the moisture to percolate dewn into the clayey B horizon

which has a greater water retaining capacity, As much of the water 1s re-

tained in the B horizon the surface soil serves as an “insulator” to evapora~

tion on the approach of the dry season. Thus the red-brown earths have a

slightly longer growing season than the grey soils of heavy texture which

dry out rapidly with the onset of summer. This is borne out in the dominant

trees of the area, the bull oak being replaced by the peppermint gum

(Eucalyptus calcicultrix) and the blue gum (E. leucoxylon).

C. COMPLEX OF GREY AND RED SOILS OF HEAVY TEXTURE

Intermediate between the red-brown earths and the grey soils of heavy

texture, which are typical of good and poor drainage respectively, are areas

in which drainage is intermediate. Patches of red-brown and grey soils of

several square yards area alternate giving a mosaic of colour and of tex-

ture. This complex exhibits crabholey formations as in the grey soils

of heavy texture and this, in some cases, may be the cause of the complex,

Often the puffs are “ironed out” by repeated cultivation thus obscuring the

crabholey formations.

In Section 363, Hundred of Tatiara, the following two profiles were taken

about 15 yards apart.

GREY SOIL RED SOIL

0-6” Grey-brown clay and slight 0-8” Red-brown sandy clay loam

lime and ironstone

6-12” Grey-btown to white clay and 8-24” Red clay

much lime 24-30” Yellow-red-brown clay with

12-22” Yellow-white clay and much lime

lime 30"— Light-yellow-brown clay with

22-36" Yellow -white clay with much lime

pockets of grey clay

36— White clay and much lime

40" Continuing

In Section PT 355, Hundred of Tatiara, ted soils exhibiting crabholey

tures predominate.

Purr

0-27” Yellow-red-brown clay with

lime

27"— Limestone

40” Continuing

struc-

CRABHOLE

Grey-red-brown sandy clay

with some ironstone

6-12” Dark yellow-brown clay with

lime

12-16" Yellow-brown clay with lime

16-40” Light yellow-brown clay

with much lime increasing

with depth

40’—. Yellow-red-brown clay with

some lime

48” Continuing

0-6"

It is obvious from the profiles that the soil has been eroded into the crab-

holes from off the erupted puffs.

Some interesting changes over a short distance are to be observed in the

soils near Section 285 of the Hundred of Tatiara, The area alongside

the roadway shows marked crabholey structure and carries a relatively dense

stand of bull oak. It has apparently been left untouched since the road was

surveyed,

In a patch of red soil these profiles can be observed.

Purr . CRABHOLE

0-12” Red-brown nutty clay (slight 0-10” Red-yellow-brown silty clay

cracks ) loam

12’— = ‘Yellow-brown clay with lime 10’- Dark yellow-brown clay

18” Continuing Yellow-brown clay with

slight lime

28” = Continuing

while only 18 yards away an area of grey soil shows

Purr ; CRABHOLE

0-12" Grey crumby clay + lime O’— Grey clay

(large cracks up to 2”. 20% Continuing

wide)

12’— Yellow-grey clay -+ much

lime

18” Continuing

On careful examination the red soil groups are found to occupy a slightly

elevated and better drained position than the grey soil groups. It appears

that the micro-topography has produced conditions for soil formation simi-

lar to those occurring on the well-drained slopes and rises and poorly-drained

level surfaces and creek-beds (see Fig. 3 (3) ). A similar set-up can be seen

in the Riverina district (Stephens—private communication) and on the

eastern extremities of the Darling Downs.

As would be expected, the growing period, texture and pH are in general

intermediate between the heayy grey soils and the red-brown earths.

Eucalyptus caleicultrix (peppermint gum) tends to dominate this area which is

transitional between the bull oak and blue gum communities,

D. SOLONIZED ‘WOODLAND SOILS

Towards the westerly half of the Hundred of Wirrega and fringing the

“Desert” soils, the red-brown earths grade into solonized woodland soils.

Superficially, little change im the vegetation is apparent, the blue gum-

savannah woodland of the red-brown earths extending imperceptibly on to

the solonized woodland soils, As these soils near those of the “Desert,”

Xanthorrhoea semiplana appears, but otherwise there is no indicator species in the

vegetation.

Ironstone gravel is. usually absent from this soil, the pink tinge of the A

horizon of the red-brown earths being replaced by a grey-brown surface soil.

The subsoil is yellow-brown to grey in contrast to the red-brown of the red-

brown earths, and shows obvious solonization, the top of the clay showing

irregular flat domes, with shallow crevices containing the A horizon between

them.

The pH of the A and B horizons is about 7-0 whereas the B horizons of

the red-brown earths are alkaline (8°5 to 9-2).

A typical profile is shown on Section 240 Hundred of Wirrega.

” Grey-brown sandy loam + organic matter

2-8” Pale-brown sandy loam

8-16” Yellow-brown clay (solonized)

16’— Limestone

E. RENpDzINAS

In the Hundred of Wirrega the grey soils of heavy texture which occur

in the areas of poor drainage of the Hundred of Tatiara are replaced by a shal-

low rendzina (the “black stony soil” of the district). This alkaline soil

(pH over 8-0) is developed over limestone on extremely flat low-lying

areas and grades into red mallee soils, red-brown earths and solonized wood-

land soils on the higher ground.

Similar soils are present near Keith in the Hundred of Stirling on the

lowest-lying area of the district (see Fig. 4).

Diagrammatic section of the woodland communities and soitg of the Hd. of Stirling

rl nds hte de nth ih a | hee SR ie i

@ E. tesciculosa > E. leucoxylon Q malatavea pubescens * Kantherrhoes

Ww E

77 Latter sand (woodland phase) = Stirling sandy clay loam

= Tendzina 7p red malice soit

Fig. 4

A typical profile is seen in

Section 523, Hundred of Wirrega

0-3” Grey clay loam + lime particles

3” ~— Limestone

As the texture is lighter than that of the heavy gtey soils the rendzina

rarely cracks in summer. Crabholey formations are never present. Being

shallow, these soils dry out rapidly on the onset of warm weather, some two

to three weeks before the surrounding soils.

Melaleuca pubescens (dry land tea tree) with occasional Eucalyptus leu-

coxylon (blue gum) is prevalent over this soil.

F, RED MALLEE SOILS

The rendzinas grade into red mallee soils and intermediate soils on every

slight rise.

On Section 23 Hundred of Wirrega, this profile is present :—

0-8” Grey-red clay loam + lime

8” Limestone

On Section 186, Hundred of Stirling, this profile is found —

0-4” Red-brown silty clay loam

4” Limestone

Roth these soils show an alkaline pH of over 8-0. They have close affinities

to terra rossa soils, but seem to be allied to the red mallee soils which are

seen neat Coonalpyn (Crocker 8).

Most of the ridges in the Hundred of Wirrega (described in the section

on topography) show similar soils wherever the deep sands have been

stripped from them. Cannonball Ridge shows red mallee soils while

Changwa Ridge shows mainly deep podsolized sands, Sand from these

ridges has altered the texture of the rendzinas which occur in the yicinity

and has tended to accumulate on the eastern sides.

G. MeEapow PopsoLs

In some of the swamps and watercourses where Eucalyptus camaldulensis

(red gum) occurs the soil approaches that typical of a meadow podsol.

Section 127, Hundred of Wirrega

0-13” Light-grey sandy clay loam

13-40” Grey clay with yellow mottling

40’— — Light yellow-grey clay and much lime

44” Continuing

The mottled B horizon is not invariably present, The sii) are very wet for

a large portion of the year.

Similar soil occurs at Swede’s Flat-

H. STIRLING SANDY CLAY LOAM

The rendzina-red mallee soil complex-of the Keith district grades into

this slightly solonized soil (see Fig, 4).

A typical profile is seen on the east side of Section 138, Hundred of Stir-

ling.

0-4” Grey-brown sandy clay loam

4-8” Grey yellow-brown sandy clay

8” Limestone

The soil type has been called the Stirling sandy clay loam. It grades

into the woodland phase of the Laffer sand.

The pH of the horizons is between 7'5 and 8-0.

This soil has a longer growing season than the calcimorphic soils adja-

ecnt to it. It supports a Eucalyptus leycoxylon. savannah woodland.

I. LAFrer sAND (WOODLAND PHASE)

The Stirling sandy clay loam grades into the woodland phase of the

Laffer sand which exhibits the following profile :—

0-2” Grey sand and organic matter

2-5” White sand

5-10” Yellow-grey sandy clay

10’— Limestone

This soil has been described by Taylor in the “Soil Sidevey of the Hundreds

of Laffer and Willalooka” (17).

The vegetation is dominated by Eucalyptus fasciculosa (pink gum) and

Xanthorrhoea semiplana (yacca), A wide transition belt with mixed blue gums

and pink gums over a grassy understorey of Danthonia, Lepidosperma congestum

and a few Xanthorrhoea semiplana occurs between the woodland phase and the

Stirling sandy clay loam (see fig. 4). The Xanthorrhoeas increase in density as

the woodland phase is approached.

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Il a1avy,

THE VEGETATION

In discussing the vegetation of the district, an endeavour has been made to

correlate the distribution of the dominant trees and formations with the govern-

ing factors of their environment, and to indicate from these the naturally occurring

associations of the district.

GREY SOIL OP HEAVY TEXTURE

Puf? Crabhole

DO t] w c

Be. 6"

ar] Crlime

™ Crlime

26"

YB & Le

mottled Crline

YB C+line

gn , 40%

RED BROWN FARTS SOLONIZED WOODLAND SOIL

GEB 8.1 » tronstone 2G aut i-a-l.

5" gravel. c ed

ge_| os

Do-g | alo

BB autty ¢ limestone

™ Ctonoh lime

Fig. 5

A. AUTECOLOGY OF THE DOMINANT SPECIES.

1. Casuarina lnehmanni (bull-oak).

This species flourishes on the grey soils of heavy texture and extends on to

soils marginal to these areas. These marginal soils are usually heavy-textured

grey and red soils, although the bull-oak is occasionally found on red-brown

earths. However, the presence of lime and, hence, an alkaline pH throughout the

soils, is a characteristic of most of the soils where bull-oak predominates, The

soils tend to dry out and crack very rapidly on the onset of the dry summer period.

This is most marked on the puffs on which the bull-oaks usually occur. It appears

from observation that the bull-oak can persist with a slightly shorter growing

petiod than most of the other dominants of the district. It usually occurs in

areas with the rainfall less than 19” per annum, This limit is actually controiled

by the soil itself, For instance, at Frances to the south of the Little “Desert,”

Tiver (18) has found bull oaks confined to similar soils with an annual rainfall

of 20 and over, A few small stands of bull oak occur on low-lying, heavy grey

soils in the Hundred of Wirrega. Here the rainfall is about 20” per annuni.

Although buil oak occurs on the heavy grey soils of the watercourses it

usually takes a position on the fringe of the watercourse where the water does not

lic as long as in the course itself.

2, Eucalyptus calcicultrix (peppermint gum).

The identification of the peppermint gum of the district has been very diffi-

cult, A great variation in habit, bark, leaf, bud and fruit characters from area

to afea and within the same atea has caused confusion. Some specimens seem

to belong to the species E. odorata, some to E. odorata vat. angustifolia, some to

E. calcicultrix, while many show intermediate characters. Boomsma (4) has

shown the complexity of these species and has explained it from an evalutionaty

standpcint. For the purpose of this paper the peppermint gums will be referred

to as E. calcicultrix, but they are really a complex with E. caleicultrix dominant.

The peppermint gums occur in areas marginal to the bull oaks which have

a slightly longer growing season, It is especially noted on the red-brown earths

around Custon and to the north of Duke's Highway near the Victorian border.

As the rainfall increases towards the west, the peppermint gums on the red-brown

earths are replaced by the blue gums (Eucalypins leucoxylon), occasional clumps

of E. calcicnltrix occurring on the top of rises where the drainage causes the red-

brown earths to dry out earlier than on the tevel country.

The peppermint gum is not confined to the red-brown earths but extends

onto the complex of grey and red soils of heavy texture, It appears then that

the presence of lime (and an alkaline pH of 7-8) in the upper horizons of the

soi] does not limit its distribution. It is largely influenced by the water relation-

ships within the soil, Such a tolerance has been demonstrated by Specht and

Perry (16) for the peppermint gum of the Adelaide Hills.

3, Eucalypins leucorylan (blue gum).

At about the 19” isohyet and above, blne gum assumes dominance over the

whole of the woodland communities of the Bordertown district, replacing the

peppermint gum which exists on areas with a shorter growing season, The blue

gum extends into ihe peppermint gum stands of lower rainfall areas {at least as

low as 18” per annum) as fringing communities on the slopes alongside the red

gum (E, comaidulensis) or box (E. laryiflorens) of the watercourses. In its turn

peppermint gun occurs on the drier ridges. within the areas dominated by blue

gums.

Within its distribution range blue gum occurs on red-brown earths, solonized

woodland soils, some heavy grey and red soils, and extends onto the rendzina—

red mallee soil complex in the Hundred of Wirrega. It tends to be replaced by

Melaleuca pubescens on the latter soil complex wherever the soil is very shallow.

The blue gtms extend over small sand ridges of the district but usually

there are swamps close at hand.

Throughout the Little “Desert” blue gums occur on flats which often become

waterlogged and swampy during winter. Even in summer the subsoil of the fats

tends to hold the moisture and hence makes an ideal habitat for the development

of blue gums.

Tt, therefore, appeats that EH. leucox lon is. distributed over many different

soils provided the water relations of these soils are suitable for its growth. ‘This

fact has been pointed out by Specht and Perry (16) in discussing the distribu-

tion of £Z,, leucoxrylon in the Adelaide Hills, There the minimum rainfall was

found to be 25 inches, but much of this rainfall is lost in run-off in the dissected

country, The lower limit of 19 inches per annum found in the Bordertown dis-

trict is therefore comparable.

The large stand of blue gums at Keith in the Hundred of Stirling is rather

puzzling. It is equivalent to a large blue gum flat of the “Deserts” except for the

rendzina-red mallee soil complex which occupies the low-lying portion of the

district. The rainfall at Keith township averages 17°87 inches per annum over

a period of 36 years, while Messrs, Moseley, a couple of miles south-west of

Keith, have recorded 18°30 inches over a period of 13 years. It appears then

RENDZUIA RED MALIZE SOIL

s CG.l.

linestons . Bet»

limestone

TAFFER BARD SITRLING SANDY CLAY rosy

DGB) s.

2 in Be1i-8.0,le

G-W a, 4”.

&*.

tT ¥e Com.cel. 53.4 Bits

limestone

13"

limestone

Fig. 6

that the area has an average rainfall somewhere in the vicinity of 18 inches per

annum. Considering the nature of the soils—shallow rendzina, red mallee soil,

the Stirling sandy clay loam and the woodland phase of the Laffer sand—one

would expect £. calcicultrix rather than E. leucoxylon to be dominant. Blue

gums have been recorded in areas with rainfall as low as 15 inches per annum

(3 and 11) but always on soils of high water-retaining capacity.

In discussing the formation of the “Deserts” it was suggested that this

area of rendzina and red mallee soils represented a swamp during the Arid Period.

It is suggested that blue gum was probably one of the dominant trees of this

swamp and as the pressure of the Arid Period was released this species spread

to occupy its present area. As climate-soil relations today are limiting for these

trees, most have developed an atypical twisted appearance resembling that of

the pink gum (E. fasciculosa) with which it occurs. The leaves, buds and fruits

show no noticeable difference from the typical forms of the Tatiara district.

4. Eucalyptus largiflorens syn. E, bicolor (river box),

E. largiflorens is often confused with the peppermint gums of the atea. How-

ever, it has the typical box bark and fruits in terminal panicles whereas the

peppermint gum tends to have a rough shaggy bark and fruits in axillary umbels.

9§

The tree is confined to the heavy-textured grey soils of the tributaries and

watercourses of the Tatiara Creek (see fig. 3 (1) }. Most of these watercourses

consist of swampy areas along which the water gradually escapes to the west.

Consequently they have a long growing period. Although some areas are flooded

all the year round, especially after a very wet season, most of the streams dry

out during the summer, , The soil is alkaline throughout and shows distinct.

crabholes.

Tiver has noted this box occtirting occasionally on the heavy grey soils of

the Frances district, It extends through the Wimmera district in similar habitats

(Patten—private communication) and is found im equivalent habitats along the

River Murray and its tributaries (1 and 20).

5. Eucalyptus camaldulensis syn. E. rostrata (red gum)-

This tree is confined to the watercourses and swamps and replaces E. largi-

florens where the texture of the surface soils is lighter. The soils usually have

meadow podso! affinities but the red gums extend on to the swampy rendzina

soils near the end of the Tatiara and Nalang Creeks.

A large area of red gum occurs on Swede’s Flat in the south-west corner

of the Hundred of Wirrega. This area becomes very wet in winter and is charac-

terised by a series of Lepidosperma swamps along its centre,

6, Melaleuca pubescens (dry land tea tree).

This tree occurs mixed with blue gums on the shallow soils of the rendzina

—ted mallee soil complex of the Hundreds of Wirrega and Stirling The

rendzinas are rarely wet and boggy in winter, Even after a heavy rain, there

are few pools lying about, Most of the excess water soaks rapidly through the

limestone which is not far from the surface. Where the soil is very stony the

tea tree becomes dominant.

It appears then that the tea tree becomes dominant on alkaline soils which

have a very short growing period. This agrees with its distribution elsewhere

in South Australia (7).

7. Eucalyptus fasciculosa (pink gum).

This gum is prevalent over the woodland phase of the Laffer sand. The soi!

is Jow in nutrients and has a low water-retaining capacity. As the texture of the

surface soil becomes heavier, blue gums occur as co-dominants and entirely replace

the pink gum on the Stirling sandy clay loam.

8. Savannah woodland formation,

This formation occurs over the whole of the richer soils of the Tatiara and

Keith districts. Danthonia spp. with Stipa spp. and Agropyron scabrum often

co-dominant, are prevalent over the whole grassland area. Although there is

little variation in the nature of the composition of the native grasses in the under-

storey, the herbs and introduced lepumes vaty greatly with the different soils.

Towards the “Deserts” Nanthorrhoea semiplana becomes prevalent in the under-

storey and finally gives way to the mallee and sclerophyll communities on the

poorer soils of the “Deserts” (see pl. iv, fig. 1).

B. CLASSIFICATION OF THE PLANT COMMUNITIES.

A glance at the soil and vegetation of the district and the foregoing dis-

cussion on the autecology of the dotninant species of the flora will serve to

indicate that several distinct vegetational associations and ecotones are: present

in the area. Au association is regarded as any naturally occurring assemblage of

plants present over a wide arca with similar environment, An ecotone is regarded

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as a transitional area between two or more associations whose species have over-

lapping environmental ranges. There is no evidence to assume that any of these

ecotones are tension belts, for as far as can be seen the vegetation is relatively

stable.

It will be seen that the following associations are present :—

Casyaring luehmanni association.

Eucalyptus calcicultriz association.

Eucalyptus leucoxylon association.

Eucalyptus camaldulensis association.

Eucalyptus largiflorens association.

Melaleuca pubescens association.

“Desert” edaphic complex.

(a) E. baxtert association.

(b) E. fasciculosa—Xanthorrhoea semiplana association.

tion.

(d) E. behriana—E. anceps association.

(e) Xanthorrhoea semiplana- Banksia ornata association.

(£) E. incrassata—heath association.

(g) E. diversifelia association.

(h) E. leucoxylon—E. fasciculosa ecotone.

SES ie OU Et

LAFFER SAND WILLALOOKA SAND

(heath) oballow phase (mallee heath)

we 8+0.Ms G 2" a

¥ * 8

e S. 7 medina ¢ to

au" GY Tt heavy C.

13 @.c.

limestone

linestone

WILLALOOKA SAND BUCKINGHAM SAND

Bormal phase (mallee broombush) (mallse dbrooabush)

6 2 6. GB srO.m,

Le "sa

YE with

GY-T medium C to - RY ey ¢

besvy C. mottiinga

limestone

36"

limestone

Fig. 7

1, Casuarina luehmanni association (see pl. iv, fig. 2).

This savannah woodland association flourishes on the grey soils of heavy

texture. The soils are characteristically water-logged in winter and dry out

rapidly at the onset of summer. Due to the pronounced crabholey nature of the

soil, microclimates are produced on the puffs and the crabholes, The crabholes

retain the moisture which runs off the puffs and are consequently very wet in

winter and have a longer growing period than the latter which dry out and crack

on the approach of the dry season. These soils occur where the rainfall is less

than 19 inches per annum, but a few areas occur, supporting bull oak, in rainfall

greater than this,

Although Danthonia and Stipa are the dominants of the native savannah

understorey, agriculture, with top-dressings of superphosphate, and grazing has

rapidly altered the former balance of species. Wimmera tye grass (Lolium

rigidum), silver grass (Vulpia myuros) and other introduced herbs have replaced

the original dominants. Statistical analysis by the Levy Point Quadrat method

(9) has shown the following percentages for the relatively untouched vegetation

under the bull oaks on Section 318 of the Hundred of Tatiara.

Puff Crabhole

Vegetation hits per 100 points - - 73 40

Bare ground, per 100 points - - 34:0 62°0

Danthonia spp. - - - - = 274% 37-4%

Danthonia sp. (prominent in crabholes) 4-1 30°0

Stipa eremaphila r = = = BOL _

*Vulpia myuros - - - = = 96 —

*Plantago bellardii ~ = = “Ss BS _—

Angianthus strictus - - - - D6 — Percentage ¢

Myriocephalus rhizocephalus - - — 100 overlapping

*Cryptostemma calendulacewm - - — wie cover

*Hypochoeris radicata - - - - 27 —

Crassula sieberiana - - + > oF —

*Medicago minima = = - - 41 —

Miscellaneous - += - - = 42 15-1

(* denotes introduced plants)

¢ Percentage overlapping cover indicates the percentage of each species hit per 100 points.

It will be noticed that the crabholes and puffs differ greatly in floristics due

to their extreme microhabitats.

A list of associated species in this association is given in the appendix. It

will be seen that the association is richer in species than most of the other woad-

land associations, This may be a result of the varied habitats which exist on

this soil.

2. Eucalyptus calciculirix association (see pl. iv, fig. 3).

As the length of the growing season increases, the Casuarina luehmannt asso-

ciation gives way to the Bucalypius calcicultrix association. This association has

a savannah woodland formation. The understorey varies slightly with the soils.

On the marginal grey soils of heavy texture and on some grey and red heavy-

textured soils the crabholey formations induce the same micro-Hloras as are

evident in the Casuarina luehmanni association, On the red-brown earths, how-

ever, the topography is relatively level and the understorey more uniform in com-

position, Danthonia is the dominant genus of the ground flora in the natural

vegetation. Howevet, many introduced species have altered the composition of

the flora,

Statistical analysis by the Levy Point Quadrat method has revealed the fol-

lowing percentages of species occurring in a roadside between Sections 108 and

110 of the Hundred of Wirrega. The soil is transitional between a red-brown

earth and some of the heavy grey and red soils,

Vegetation hits per 100 points- - - 61

Bare ground, per 100 points - - - 49'5

Danthonia sp,- - - - - = 724%

*Pog bulbosa - - -~ - - - 139

Stipa sp.- - - > = = - 16 Percentage

*Romulea rosea - = = ee 57 overlapping

Erodium botrys == - ~ - - = 16 cover

*Trifolium subterraneum - - - 416

Miscellaneous -_ 9 - 32

(* denotes introduced species}

A list of species occurring in this association is given in the appendix. It will

be noted that the association shows species which occur either in the Caswartna

leukmanni association or the E, leucoxylon association, The soils of the E. calci-

culfvix association are transitional between these two associations.

3. Eucalyptus leucoxylon association (see pl, iv, fig. 4).

This association replaces the FE. calcicultrix association at about the 19-inch

isohyet and wherever the water relations within the soil are favourable. The

association is a savannah woodland formation with an understorey similar to that

of the previous association where it occurs on red-brown earths and solonized

woodland soils. A list of species recorded in this association is included in the

appendix. The following percentages of species were obtained from a roadside

between Sections 276 and 277 of the Hundred of Wirrega, This soil is a red-

brown earth.

Vegetation hits per 100 points - = - - 76

Bare ground, per 100 points —- - - 3670

Danthonia sp.- - - - - = 491%

Stipa sp, ion = - - 15:9

"Poa bulbosa - > - - - - 46

*Pulpia myuros el FF + sc + OH Percentage

*Trifolium angustifolium - = - - - 10:6 overlapping

*Romulea rosea - - = = = 26 cover

Leptorrhynchus squamatus - - - 2°6

Oxalis corniculata - - - - = 2:0

Miscellaneous - « - - - 473 /

(* denotes introduced species)

The E, leucoxylon association occtitring on rendzinas and red mallee soils

at Keith is essentially similar ta that of the Bordertown district. Snvall variations

due to the alkaline soils are apparent in the understorey (see appendix).

4. Eucalyptus camaldulensis association (see pl. v, fig. 1).

This association follows watercourses and fringes swamps wherever the

surface soil is lighter than a clay. Often trees are seen growing throughout a

swamp but if the water is persistent for long periods the red gums are confined

to the fringe of the average low water mark.

A list of associated species is given in the appendix.

5, Eucalyptus largiflorens (see pl. v, fig. 2).

From the evidence available in this district it is difficult to define the E. largi-

florens as a definite association, for Casuarina luehmanni tisually occurs associated

100

with it on the heavy grey soils of the watercourses, However, it is quite often

noted that the bull oak tends to form a fringing community along the edge of the

watercourses while the box is left alone in the shallow stream-bed where it may

be swamped for most of the year. A well-defined association with this specits

as dominant has been recorded along the Murray and its tributaries by Wood 20)

and Beadle (1). The understorey of this association on the Murray watersheds

varies considerably depending on its locality, and shows few species identical with

those recorded for the Bordertown district. Most of the species of the

Casuarina Inehmenni association are found in this association,

6. Melaleuca pubescens association (see pl. vy, fig. 3). ash

This association is' well defined in the Lower South-East, especially on the

terra rossas of the Woakwine Range (7). It is approached in the Bordertown

and Keith districts in only a few localities on ridges of red mallee soils and on

very stony, well-drained rendzinas. In most cases the tea tree ig associated with

blue gum, forming an ecotone between the Melaleuca pubescens association and

the E, leucoxylon association.

A list of associated species is recorded in the appendix, Darthonia and S tipa

are the dominants of the savannah understorey, but have been displaced by the

Introduction of Carthamus lanatus and C, glatcus (the star thistle) in many

areas, These species all thrive on the well-drained alkaline soils.

7. “Desert” edaphic complex,

A complex of associations and ecotones exists. on the solonized and pod-

solised soils of the “Deserts,” Coaldrake (6) gives a detailed account of these

associations in an ecological survey of the Buckingham suite of the Ninety-Mile

Plait, Jessup (11) has dealt with some of the associations which dccur on the

western extremity of the “Desert,” and Crocker (7) with some of the southern

extremity. Taylor in his “Soil Survey of the Hundreds of Laffer and Willa-

looka” (17) has indicated some of the major vegetation communities which exist

in these Hundreds. This vegetation extends into the Hundred of Stirling and

to a limited degree into the western edge of the Hundred of Wirrega. It is

composed of the following associations —

(1) Xanthorrhoca semiplana— Banksia ornata association ( heath) occurs on

the normal and shallow phases of the Laffer sand. This association has

numerous species which often assume co-dominance within the asso-

ciation (see pl. vi, fig, 2),

—

Eucalyptus fasciculoso —Xanthorrhoca semiplana association (pink gurn,

yacca) occurs on the woodland phase of the Laffer sand. The

associated species are essentially sclerophyllous (see appendix). Occa-

sional blue gums occur throughout the pink gums,

(3) Eucalyptus incrassata—E, leptophylla— Melaleuca uncinata association

{mallee-broombush) is found on the normal phase of the Willalooka

sand (see pl. vi, fig. 3).

—

Eucalyptus diversifolia association occurs wherever the limestone is

close to the surface in the shallow phase of the Willalooka sand, The

associated vegetation is scrubby, with heath plants and-some Melaleuca

uncinata (see pl, vi, fig. 4).

(5) Lucalyptus incressate—heath association occurs on the shallow phase of

the Willalooka sand.

101

The Bangham Scrub of the Little “Desert shows predominantly deep pod-

solised sands supporting a Lucalyplus baxteri association with E. leucoxylon

occurring on small, damp hollows, The E. baxteri tends to be stunted in ¢com-

parison with the trees which occur in the higher rainfall of the Lower South-

East (see pl, vi, fig. 1). It continues north into the Big “Desert” wherever

deep sandy ridges occur. The association is a selerophyllous woodland with an

understorey essentially similar to that described by Crocker (7).

A mallee-broombush (E. incrassata—E. leptophylla—Melaleuca uncinata)

association is prevalent between Swede’s Flat and the woodland communities of

ihe Bordertown district, The soil consists of a shallow sand (4-6 inches deep)

over a deep red-mottled clay which shows marked solonization. This

soil markedly differs from that of the same association in the Hundreds of Willa-

louka, Laffer and Stirling—the normal phase of the Willalooka sand, The asso-

ciation occurs on similar soils to the north of the Bordertown district. Coal-

drake (6) has termed this soil type the Buckingham sand,

Eucalyptus behriona occurs mixed with E. anceps and an occasional mallee

form of £. calcicultrix on grey soils of heavy texture marginal to the Big “Desert”

communities near the Victorian border. A stand of &, behriana on its own is to

be seen on Section 439 of the Hundred of Tatiara. These mallee communities

have been grouped for convenience under a &, behriana-E, anceps association.

8. Excalyptus leucorylon—-E. fascieulosa ecotone (see pl..v, fig. 4).

A transitional community of mixed E. leucoxylon and EB. fasciculosa occurs

between the E. leucoxylon association and the &. fasciculosa—Xanthorrhoes

semiplana association of the Hundred of Stirling (see fig. 4). The former

occurs on tendzinas, red mallee soils and the Stirling sandy clay loam, and

the latter on the woodland phase of the Laffer sand. The soils grade the one

into the other with a corresponding transition of one plant association into

another. The understorey of the ecotone is dominated by Denthoma and Stipa

on the blue gum side, then Lepidosperma congestum, and finally Xanthorrhoe,

Lepidosperma congestum and other heath species on the pink gum — yacca side.

The “blue gum flats” of the Bangham Scrub in the Little “Desert” can be

classed in this ecotone, These damp hollows occur within the Z. baxteri associa-

tion of the deep podsolised sands and are dominated by EF, lewcoxylon. Occasional

trees of £, fasciculosa often occur around the fringe of the “fat” and are some-

times co-dominant. The understorey is tsually an admixture of grasses

(Danthonia and Stipa) with a few sclerophyllous bushes from the surrounding

E, baxteri association, —

The FE. leucoxrylon—E. fascicuiosa association which Crocker records neat

Bool Lagoon and south of Lucindale in the Lower South-East (7) would be

better placed as an ecotonal community between the E, leucorylon and the

E. fasciculosa —Xanthorrhoeg associations. (In the Lower South-East the yacca

is usually X. australis, while X. semiplana tends to predominate in the Upper

South-East).

The herb stratum of this ecotone showed the following percentage composi-

tion on the roadside near Section 9SW of the Hundred of Stirling.

102

Vegetation hits per 100 points: - - 47

Bare ground, per 100 points - - - 53:0

Stipa sp. ~ & + + = = BN

Neurachne alopecuroides - - - - 11°0

*Vulpia myuros - = = = = B88

Danthonia sp. - - - - - - 33

Lepidosperma congestum - - - 3:3

Lepidosperma carphoides - = = 22 Percentage

Sedge (unidentified) Ss = 7 5S overlapping

*Trifolium arvense - - = - 19+7 cover

*Trifolium procumbens - - - 55

*Trifolinm glomeratum - - - 2-2

Caesia vittata - - - = = - 12-1

*Hypochoeris radicata -~ - - - 44

Miscellaneous o> 4 th Ue 866

(* denotes an introduced species)

A list of associated species is given in the appendix.

ACKNOWLEDGMENTS

The author wishes to express his sincere appreciation of the help and advice

of many members of the Agronomy Depattment of the Waite Agricultural

Research Institute, C.5.I.R.O. Soils Division and Dr. J. G. Wood of the Depart-

ment of Botany, University of Adelaide.

Special thanks are due to Mr, K. Phillips who is responsible for most of the

photography.

REFERENCES

(1) Beapve, N. C. W. 1948 The Vegetation and Pastures of Western N.S.W.

Govt. Printer, Sydney

(2) Buacx, J. M. 1921 Flora of South Australia. Govt. Printer, Adelaide

(3) Boomsma, C. D. 1946 The Vegetation of the Southern Flinders

Ranges, Trans. Roy. Soc. S, Aust., 70, (2)

(4) Boomsma, C. D. 1949 Nomenclature of Eucalypts, with Special Refer-

ence to Taxonomic Problems in South Australia. Trans. Roy. Soc.

5. Aust., 72, (2)

(5) Bursince, N. T. 1947 Key to the South Australian Species of Eucalypts.

Trans. Roy. Soc. S. Aust., 71, (2)

(6) Coatpraxe, J. E. 1950 A Study of the Climate, Soils, Geology and Plant

Ecology of Portion of the Ninety-Mile Plains, South Aust. Aust.

C.S.LR.O, Bull. (in press)

(7) Crocker, R. L. 1941 The Soils and Vegetation of the Lower South-

East of South Austtalia. Trans, Roy. Soc. S. Aust., 68, (1)

(8) Crocker, R, L. 1946 Post-Miocene Climatic and Geologic History and

its Significance in the Genesis of the Major Soil Types of South Aust.

Aust. C.S.LR. Bull, 193

(9) Crocker, R. L., and Tiver, N. S. 1948 Survey Methods in Grassland

. Ecology. Journal British Grassland Soc., 3, No, 1

(10)

103

Crocker, R. L., and Woop, J. G. 1947 Some Historical Influences on

the Development of the South Australian Vegetation Communities and

their bearing on Concepts and Classification in Ecology. Trans. Roy.

Soc. S. Aust., 71, (1)

(11) Jessup, R. W. 1946 Ecology of an Area adjacent to Lakes Alexandrina

(12)

(13)

(14)

(15)

(16)

(17)

(18)

(19)

(20)

and Albert. Trans. Roy. Soc. S. Aust., 70, (2)

Leeper, G. W. 1948 Introduction to Soil Science. Melbourne Univer-

sity Press

Miunyikan, C. R, 1938 A pretiminary Note on the Relationship of Zinc

to Disease in Cereals. J. Agric. Vict., 36

Prescott, J. A. 1931 The Soils of Australia in relation to Vegetation

and Climate, C.S.L.R. (Aust.) Bull, 52

Prescott, J. A. 1944 A Soil Map of Australia. C.S.1.R. (Aust.),

Bull. 177

Specut, R. L., and Perry, R. A. 1948 The Plant Ecology of Part of

the Mount Lofty Ranges. Roy. Soc. S. Aust., 72, (1)

Taytor, J. K. 1933 A Soil Survey of the Hundreds of Laffer and

Willalooka, S, Aust. C.S.LR. (Aust.) Bull. 76

Tiver, N.S. 1946 Thesis for M.Sc. Adelaide University

Trumsie, H. C. 1948 Rainfall, Evaporation and Drought Frequency in

South Australia. Journ. Agric. (S.A.), Sept. 1948

Woop, J. G. 1937 The Vegetation of S. Aust. Govt, Printer, Adelaide

104

APPENDIX

Comparative floristic lists are given for seven major vegetational groups

occurring within the area,

(1) Casuarina luehmanni association,

(2) Eucalyptus calcicultrix association.

(3) E. leucoxylon association occurring on red-brown earths and solonized

woodland soils.

(4) E, leucoxylon association and E, leucoxylon—Melaleuca pubescens

ecotone occurring on rendzinas and red mallee soils.

(5) E. fasciculosa— Xanthorrhoea semiplana association

(6) E. leucoxylon—E. fasciculesa ecotone.

(7) E. camaldulensis association.

No indication is given as to the percentage frequency of each plant, the

x only indicating the presence of that species within that group. The nomencla-

ture of the species is that given by Black (2). An asterisk before the name of a

species indicates that the species have been introduced into South Australia.

. a @ @® ® © (6

Marsilea drummondii at ite a . = = = ba =

Potamogeton tricarinatus _.... 70 mt = = - 3 1m

Themeda australis... =< nae uct Se — x x = x —

Neurachne alopecuroides __.... ne whe = = = x x

Panicum prolutum _,... baal weet ape ON x = i cs = x

*Phalaris minor ved me ee eee = =

*P, tuberosa __.... Sate sds nt ony za =

Stipa eremophila we a) _ wi ot x

Deyeuxia quadriseta .... st ests mt ee

*Molineria minuta cine vase pent ne

*Avena fatua os -.. ay Yeas Ate wx

Danthonia caespitosa .... x

*Briza minor _.... wes ‘ase wit gt oe

Eragrostis brownii .... bn sibs oo =

*Poa annua site en fase a a

*P, bulbosa wits $08 fe sat ee ll

*Vulpia myuros x

*Scleropoa rigida mes ae ‘aes nn |

i a |

Cn |

aw mM I !

i I

ame I |

| !

4 #4 I

Pe et, |

“a |

*Bromus rigidus

*B. rubens ne ry “See 7

*B. mollis 0, aes no Fs. mS

“Brachypodium distachyon _.... uly ne = Oo

*Cynodon dactylon — .... ine wast ane

Chloris truncata

*Lolium rigidum

Agropyron scabrum ....

*Hordeum murinum

*H. maritimum ....

Scirpus antarcticus

Eleocharis acuta

Lepidosperma congestum

L. viscidum =... _ -_ ane

L. carphoides ..,, wet

Gahnia lanigera

mw mA we TEL mw

ee ee ee ee |

i | I

| |

$ | {

| |

KK AR wm |

a RK I

mow

4 |

{

tal

Chorizandra enodis __....

Carex inversa ....

Juncus bufonius

J. prismatocarpus

J. pauciflorus

Dianella revoluta

Burchardia umbellata

Anguillaria dioica

Caesia vittata ad

Chamaescilla corymbosa

Bulbine bulbosa

Dichopogon fimbriatus

Xanthorrhoea semiplana

X. australis =... wats

*Romulea rosea ....

*Homeria collina

Casuarina stricta

C. luehmanni __«.... sade

C. muelleriana ....

Hakea rugosa ... ate

Banksia ornata

Loranthus exocarpi

L.. linophyllus ...,

*Rumex brownii

*R. acetosella.... oe

*Polygonum aviculare

Chenopodium pseudomicrophyllum

Ptilotus exaltatus

P. macrocephalus

P. spathulatus .... ei

Claytonig australasica

*Cerastium semidecandrum

Spergularia rubra

*Vaccaria segetalis ....

Clematis microphylla

Ranunculus lappaceus

*Papaver sp. dyes ann

*Fumaria parviflora

*Sisymbrium orientale ....

Lepidium hyssopifolium

Drosera glanduligera

D. whittakeri .... eees

D, auriculata

Crassula sieberiana

C. pedicellosa .... seat

Bursaria spinosa

Billardiera scandens ....

Acaena ovina .... vir

Acacia acinacea

A. dodonaeifolia

A. pycnantha~—.... vite

A. rupicola

A. farinosa

eee

thee

Am 8

Eutaxia microphylla ..., one

Phyllota pleurandroides wed

*Trifolium proczmbens ihe

*JT, tomentosum bite a

*T, glomeratum sate we

*T. subterraneum = das

*T, scabrum fies seo ise

*T. striatum on tee évar

*T. arvense ar wr er

*T. angustifolium sor ae

*Medicago sativa sees fas

*Medicago tribuloides

*M,. denticulata dete

*M, minima af hex ae

Swainsona procumbens var. parviflora

Kennedya prostrata ....

Geranium pilosum —.... webs

*Erodium cygnorum. ... wt

*E, botrys text eve nate

*E, moschatum .... side are

*E,- cicutarium .... ze suas

Pelargonium rodneyanum

Oxalis corniculata ...,

*O. cernua tytis “ib me

Euphorbia drummondii —-

Pimelea humilis .... ne chi

Lythrum hyssopifolia ast

Leptospermum myrsinoides

Melaleuca pubescens .... woot

M. uncinata —.... ae Slee

Eucalyptus camaldulensis _....

E. leucoxylon .... as dat

E, fasciculosa ... ver ole

E. calcicultrix .., .... be

*Oenothera odorata —....

Halorrhagis heterophylla

Hydrocotyle laxiflora .... :

Bupleurum semicompositum

Eryngium rostratum te

Astroloma humifusum Atty

*Anagallis arvensis .... sis

*A, femina fs sis diss

*Erythraea centaurium a0

Convolvulus erubescens tt

*Helictropium europaeum _....

*Lithospermum apulum ..., wipe

*Echium plantagineum akis

Teucrium racemosum Sts

Mentha saturejoides .... ass

*Marrubium vulgare. .... vhs

Solanum nigrum a: bons

*Linaria elatine "dee

*Bartschia latifolia ais one

wo OM

xx ew

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Vol, 74, Plate 1V

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Soc. 5. Aust., 1

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Trans,

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Vol. 74, Plate V

Aust., 1950

Roy. Soc. S. /

Trans.

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*Plantago lanceolata 44

*P, bellardii unig wat es

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Asperula scoparia

*Sherardia arvensis .... shi

Wahienbergia gracilis

Lobelia pratioides _.... dans

Pratia concolor 7 ante!

Goodenia robusta the aaa

107

G. heteromera .... ie sie -

G. pinnatifida .... seid fe a

‘Brachycome graminea Lins fess

B. goniocarpa .... at wiiee avée

Calotis cymbacantha ...,, jose asi

Vittadinia triloba

Centipeda minima

Cymbonotus lawsonianus

*Cryptostemma calendulaccum

Gnaphalium japonicum "

Helipterum corymbiflorum ....

H. australe ie tne

H, pygmaeum .... tee eh iz

Helichrysum semipapposum var.

folium Res bs wa4 cet

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Leptorhynchus squamatu

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Myriocephalus rhizocephalus

Angianthus strictus .... sore

Calocephalus citreus

Craspedia globosa 7

Craspedia uniflora .... opt

*Cirsium lanceolatum. ....

*Carduus tenuiflorus. .... dain be

*Silybum marianum _.... ih Are

*Ornopordon acaule ....

*Centaurea calcitrapa ....

*Carthamus lanatus*

*C. glaucus af dese ois ome]

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*Hypochoeris radicata at

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woM |

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4 4 I

CALCAREOUS TUFA DEPOSITS IN NORTHERN NEW GUINEA

BY PAUL S. HOSSFELD

Summary

The widespread occurrence and formation today of calcareous tufa deposits in many of the

torrential streams of the coastal ranges of northern New Guinea are described, also the features

produced by these deposits. It is suggested that the severe dissection by those streams which at

present are building up their channels was accomplished during a time when the climate exhibited a

marked differentiation into wet and dry seasons. The advent of more evenly distributed precipitation

resulted in the formation of numerous springs which, because of their very small catchment areas,

are made permanent only by the almost daily rainfall.

168

CALCAREOUS TUFA DEPOSITS IN NORTHERN NEW GUINEA

By Pauv 5. Hossrerp®

[Read 9 November 1950]

SUMMARY

The widespread occurrence and formation today of calcareous tufa deposits

in many of the torrential streams of the coastal ranges of northern New Guinea

are described, also the features produced by these deposits. lt is suggested that

the severe dissection by those streams which at present are building up their

channels was accomplished during a time when the climate exhibited a marked

differentiation into wet and dry seasons. The advetit of more evenly distributed

precipitation resulted in the formation of numerous springs which, because of their

very small catchment areas, are made permanent only by the almost daily rainfall.

The climatic change may coincide with the termination, or recession ftom its

maximum, of the Wiitm Glaciation.

The existence of tufa deposits in streams is a well-known feature of many

limestone regions. The occurrence and formation today of such deposits in

Northern New Guinea with its very high rainfall and steeply-graded juvenile

drainage, appears to indicate recent climate changes.

In New Guinea the occurrence of tufa is widespread. It was observed

by the author in the three deeply-dissected regions which form the moun-

tainous hinterland of Madang, Aitape (Raggatt, 1928) and Vanimo respec-

tively, All these areas are relatively close to the coast and the last two par-

ticularly are subject to a very high rainfall even in the so-called dry season,

more correctly referred to as the “less wet” season.

Cainozoic limestones are plentiful in many areas. In others, richly fos-

siliferous mudstones and marls are the sources of the calcium carbonate. A

small percentage of streams have their sources in igneous rocks or in sedi-

ments low in calcium carbonate. These do not exhibit tufa formation except

in a minor degree where small springs or seepages occur. With very few ex-

ceptions, those streams, the sources of which are springs issuing from lime-

bearing rocks such as litnestones and caleareous sandstones and mudstones,

are depositing tufa in their upper reaches.

These deposits are of several types. The commonest and most spectacu-

Jar formation is the building up of masses of tufa at the lips and on the rock

faces of waterfalls. It is well-known that in northern New Guinea the gener-

ally most practicable, and geologically the most profitable traverses are

along the stream beds, The ascent of the numerous waterfalls encountered

is impossible in many instances. In others the deposits of tufa provide a

means of ascent which, however, may still be laborious and dangerous. The

occurrence of tifa deposits on such features is surprising at first, but is so

cammon that it is soon taken for gtanted.

This deposition of tufa on the lip and face of a waterfall has a two-fold

effect. Not only does it prevent the normal recession of this erosion feature,

but the gradual growth downstream of the deposit causes an advance of the

School of Geology, University of Adelaide,

Trans. Roy Soc, §, Aust., 74, (1), March 1951

109

waterfall and a gradual diminution downstream of its height until the end

result is reached in the form of a regularly sloping ramp of tufa. It 1s con-

sidered probable that the angle of slope of the ramp is dependent on velocity

and volume of water, amount of available calcium carbonate and the incidence

of floods,

- eerrm REY ie

w | wéivw GUCNEA

[~-

x! Side

o «

~ | See >

=! a] ee

» | is

‘ .

| PAPUA m7

™~

Fig. 1

Ramps of such origin were found in a number of instances, Most of them

are covered by considerable volumes of water which, foaming over the rough

surface, form a beautiful spectacle but cannot be traversed. Two instances

were surveyed where the water enters near the top and issues at the foot of

the deposit, thus forming a dry ramp (fig. 2). Only those who have had to

force their way through trackless jungle for months or to spend week after

week traversing and surveying running streams will appreciate the pleasure

experienced in suddenly encountering a feature such as these dry ramps. They

resemble a roadway, which though steep, gives a good grip because of its

rough surface. For a short time it is possible to walk on a clean surface with-

cut stumbling over roots or hidden boulders or through morasses.

The two dry ramps were surveyed and both have a grade of approxi-

mately 1 in 3, or 18 degrees, but this may not be a constant figure for all such

features. The longer tamp, occurring in a small tributary of the Barum

River in the Madang district, has a length of 320 feet and follows the curve

of the narrow gorge in which it occurs (fig. 2).

All stages were observed, from the thin surface coating of the lip and

face of a waterfall to pendant growths of various shapes partly coalescing,

and continuous masses from the top to the bottom of the stream channel, but

showing a decrease in height downstream. Although the orderly growth

downstream of these deposits is interrupted at times by the breaking off of _

large overhanging masses, the over-all result is the gradual building up down-

stream of these formations.

110

The final result of this constructive process is the elimination of water-

falls, and because of the resistance to stream flow by the rough surface of

the tufa, a considerable reduction in velocity.

Another feature, noticeable particularly in, and confined probably to

areas of extensive limestones is the formation of bars across the stream

(Danes, 1910) (Cotton, 1941). Even where the grade is relatively steep, this

produces a series of terraced pools at successively lower levels, éach one dis-

charging as a minute waterfall into the pool below.

Fig. 2

The bars though naturally somewhat irregular, are curved, and convex

downstream. Where well developed, they interlock to such an extent that

they form an intricate and irregular pattern. These tufa bars are formed

apparently where the stream cascaded over an obstruction such as a rocky bar

or boulder or any other obstacle to its fow. In addition to checking the flow

and reducing the erosive power of the stream to a negligible quantity, these

pools are basins of deposition. The supply of detritus from the steep banks

and also that brought down by floods, tends gradually to raise the floor and

would eventually eliminate the pools. This tendency is assisted by the

deposition of tufa between the detrital material thus rendering much of it im-

movable. However, as the deposition of material in the pool proceeds, so in

many instances does the building up of the tufa bars.

In those reaches where pools are filled due to too gteat a supply of detri-

tal material, the resulting irregular surface will ensute the formation of other

bars and pools. The result of such processes is the gradual filling of the

existing gorges. One of the best instances observed is that of the middle

segment of the Daunda River. This river which discharges into the sea near

Vanimo, detives its water from springs issuing from the coral limestones

capping the dissected Omili Plateau (Fig. 3). This stream has a very steep

gradient, parts of its gorge being inaccessible, but nevertheless, it has ceased

eroding its channel and is engaged in filling its gorge by means of the ter-

raced pools and the downstream growth of its waterfalls. The frequent

floods. which, owing to the small catchment area, ate of short duration, appear

to haye little or ne ability to remove the material built up during its periods

; iil

of normal flow. Such denia] not only in the case of the Datunda River, but

also in the very numerous instances observed in northern New Guinea, of

the normal processes of erosion of juvenile streams, implies a relatively recent

change of conditions. The widespread and yatied occurrences of these con-

structive processes are such that changes in grade due to local diastrophism

cannot be considered, Further, instances were observed of streams adjacent

te each other and with a similar history and development, but in which those

which had no calcareous rocks neat their source were actively deepening

their channels while those which were fed by calcareous springs had ceased

eroding and were building up their beds. The other change of environment

which must be considered is that of climate and the possibility of the present

cycle having been preceded immediately by one in which the incidence of rainfall

was different from today.

@HILI

PLATEAU

PLATEAL

(LIMESTONE

Fig. 3

The present climate is such that deposition of tufa proceeds at a faster

rate than can be removed by erosion. Such erosion does not take place now

during periods of normal flow, but is restricted to times of flooding. It might

be contended therefore that an increase in the occurrence, duration and

severity of floods would produce greater erosion and if such increase were

sufficiently great, remove tufa deposits faster than they could be formed dur-

ing the periods of normal flow, which obviously would be reduced greatly

both in number and duration, However, the very high rainfall experienced

in some of the areas examined, a rainfall so high that in some localities ab-

sence of rain for three days in the dry season was considered a drought, sug-

gests that a much higher rainfall in recent times is improbable. It is a pos-

112

sibility, however, that such may have been the case, and the development of

the deep gorges and intense dissection could be ascribed to such a wetter

period, when the duration of norrial flow and hence of tufa formation would

be decreased and the times of severity of erosive processes increased con-

siderably.

The other possibility, that the climate was drier, or that the rainfall was

restricted to a definite season only, appears to be supported by more evi-

dence.

It is obvious that the deposition of the tufa is dependent on springs

charged with calcium carbonate, At present these springs appear to be per-

manent in the great majority of cases observed, There are some small springs

which flow intermittently but these do not produce significant deposits. Any

decrease in the amount or duration of flow of the springs would decrease the

production of tufa.

The greater proportion of the springs which supply the headwaters of

the various streams have very small catchment areas and are short-lived,

depending for their permanence on the frequent and almost daily rains, Many

of them cease to flaw after two or three days without rain. A prolonged dry

season would result in the cessation of Aow tn all except the larger streams

which are supplied by deep-seated springs. There would then be no long-

continued supply of calcareous spring water to build up the tufa deposits.

Such small deposits as could be formed would tend ta be removed during the

periodical fooding of the streams, As stated above, there are very numerous

examples of severe dissection and deep precipitous gorges where grades are

still very high but active deepening has ceased. These features suggest there-

fore that such erosion took place when the climate was different from that of

today in so far as it was divided much more sharply into wet and dry sea-

sons and probably a smaller total annual precipitation, a climate similar to

that of northern Australia today. Small isolated remnants of sclerophyll

vegetation on exceptionally porous rocks such ag limestones and gravel ridges,

and surrounded by a luxuriant rain forest, support the belief that a prolonged

dry season was a feature of the former climate, The discovery and survey

by the author of the Pusele Creek supplies strong supporting evidence.

The Pusele Creek which flows into the Daunda River (fig. 3), has a

total length of approximately 2,100 feet. Although short, this creek dis-

charges a considerable volume of water, It has no direct catchment area

and carries away only such of the rain as falls on it or the spaces between

its distributaries. The creek is formed by several strong springs issuing

wt the foot of the limestone cliff which is the edge in this area of the Omili

Plateau (Fig. 4), This plateau consists of coral limestone and is approxi-

mately at 2000 feet above sea-level.

These springs flow down a slope of approximately 9 degrees, which

steepens rapidly to 18 degrees within the first 1500 feet and then becomes

very much steeper until it reaches the top of the Daunda Gorge (Fig, 5),

The springs unite, form distributaries and reunite to form a bewildering

anastomosing pattern compatable to a river delta. This network exists,

however, om the steep slopes referred ta above, and what is more, this steep

slope is itself a spur from which the surface drops relatively steeply on both

sides (Fig. 6), The network of the Pusele Creek occupies therefore the

steeply sloping crest of a spur, The Pusele Creek and its various distribu-

taries have not excavated any channels or valley but represent a truly perched

stream which flows at a level higher than the adjacent surface, This is pus-

113

sible only because deposits of tufa form the walls or miniature levees which

hold the various streams in position but do not prevent partial spilling over

from time to time and therefore changes in the pattern. That the tufa de-

posits are not capable permanently of retaining this perched stream in its

unstable position is shown by the existence of three channels which have

found their way to a lower stream to the south-west. It is clear that once

PLATEAU P= 99

Fig. 4

such a new stream course is established it will remain, and eventually the

whole of the Pusele Creek will be diverted to the lower levels adjacent to the

spur. It is obvious that if a period of greater rainfall had preceded the pre-

sent cycle then such capture would have taken place more speedily and the

Pusele Creek, had it existed then, would have had a short life only, If,

however, a climatic cycle with prolonged dry seasons preceded that of today,

LIMESTOWE CLIFF

GORGE OF

RIVER DAUH DA

RONG. PROFILE OF PUSELE CREEK

44D

Fig. 5

then springs would be non-existent or flow for very short periods only and

no creek would exist where the Pusele flows today, A change to the present

climate, a gradual growth in volume and duration of the present springs

would produce gradually the tufa-bordered channels with their intricate net-

work of intersecting channels.

114

It might be suggested that recent fault block movements were respon-

sible for the elevation of the limestone and the development of the springs.

The limestone is part of a large, formerly very extensive, high level area of

coral limestone. There is no doubt that the region owes its dissection and

the severity of its topography to such elevation. This occurred, however, at

a time far enough distant to permit of the dissection of the region, Events

such as cessation of erosion because of tufa deposition are of later date and

cbviously caused by climatic changes.

PUSELE CREEK

am a TUFA

TRAMSVERSE PROFILE OF PUSELE CAEEK

geo io

AO 2200 FECT

Fig. 6

The observed features suggest therefore that, until relatively recent

times, the climate of northern New Guinea had been one of marked division

into wet and dry seasons and that because such a sharp differentiation no

longer exists, deposition of calcareous tufa by permanent and semi-perma-

nent springs is not only checking erosion but is also filling up the gorges

excavated during the former cycle.

REFERENCES

Danes, J. V. 1910 “Physiography of some Limestone Areas in Queensland.”

Proc. Roy. Soc. Old., 23

Raccatt, H. G. 1928 “A Geological Reconnaissance of Part of the Aitape

District, Mandated Territory of New Guinea.” Proc. Roy. Soc. Qld., 40

ANGLO-Pers1an Or, Company 1931 “The Oil Exploration Work in Papua and

New Guinea by the Anglo-Persian Oil Co., on behalf of the Common-

wealth Govt. of Aust., 1920-29,'2 and 3

Corron, C. A, 1941 “Landscape.” Cambridge University Press

THE ARCHEAN COMPLEX AT HOUGHTON, SOUTH AUSTRALIA

BY ALAN H. SPRY

Summary

This paper deals with the petrology of a group of Archaean rocks near Houghton, South Australia.

The complex consists of a range of highly metamorphosed sediments ranging in character from

schists and gneisses to rocks resembling altered acid and intermediate igneous types. The most

abundant rock is a coarse augen gneiss which frequently contains sillimanite or garnet. This has

resulted from high-grade regional metamorphism and potash metasomatism on an argillite followed

by marked retrograde metamorphism.

115

THE ARCHEAN COMPLEX AT HOUGHTON, SOUTH AUSTRALIA

By Avan H, Spry *

[Read 9 November 1950]

SUMMARY

This paper deals with the petrology of a group of Archean rocks near Houghton,

South Australia, The complex consists of a range of highly metamorphosed

sediments tangitg in character from schists and gneisses to rocks resembling

altered acid and intermediate igneous types. The most abundant rock is a coarse

augen gneiss which frequently contains sillimanite or garnet. This has resulted

from high-grade regional metamorphism and potash metasomatism on an argillite

followed by marked retrograde metamorphism.

The rocks of igneous appearance which have been called the “Houghton

Diorites” are granulites derived from lime-magnesia rich sediments by high-grade

regional metamorphism combined with potash and soda mctasomatism. Some

sandstones have heen feldspathized, giving rise to white feldspar rich rocks for

which the term leticocrat or leucocratic granulite has been used to replace Benson's

term “gneissic aplite’, There are notable amounts of phyllonitic schists which

have been formed from both gneisses and granulites by retrograde metamorphism.

The migmatitic complex was closely folded during the Archean, and averlain

unconformably by sediments in Late Proterozoic times.

The Archean rocks occupy the core of a slightly overturned anticline of

Lower Palaeozoic age. The schistosity in both the Archean and Proterozoic

rocks is generally parallel to the axial plane of this fold. The ares was pene-

plained, and then block faulted in the Tertiary.

LOCATION

The area ig situated to the north and east of the town of Houghton, which

is twelve miles east of Adelaide, in the Mount Lofty Ranges. The Archean

inlier is roughly lenticular in shape, being 16 miles long in a northerly direction

and five miles east-west at its widest part. It extends trom Castambul to Chain

of Ponds on the River Torrens, northwards through the Humbug Scrub to a point

west of the Barossa Reservoir.

PREVIOUS INVESTIGATIONS

The accessibility and economic prospects of these crystalline rocks have led

to their investigation by a number of writers. The occtirrence of gneisses, believed

to be possibly Silurian, in the Humbug Serub was mentioned by Brown and

Woodward (1885). A further brief mention of the same rocks was made hy

Howchin (1906), who related them to the Archean. Benson (1909) carried out

a detailed study of the rocks near Houghton, and described those banded

crystalline rocks which have a chemical composition resembling an igneous rock

as the “Houghton diorite’. He believed them to be of igneous origin, formed

by intrusion of the “Houghton Magma”, He refers to them as being Algonkian

in age.

England (1935) demonstrated the chemical similarity of rocks from various

parts of the State, believed to be of Archean age. It is unfortunate that this work

was of a petrographic nature on more or less unrelated specimens and not sup-

ported by detailed field work, Hossfeld (1935) discussed briefly the Humbug

Scrub gneisses, atid stated that “the sedimentary nature of most of these rocks

* Department of Geology, University of Adelaide.

rans. Roy Soc. &. Aust, 74, (1), March 1951

116

ARCHEAN

a AUGEN GNEISSES AND SCHISTS

CZ) semsts

PROTEROZOIC

BASAL SANDSTONES

SQ sate

SANDSTONE

DIP OF SEDIMENTS

SCHISTOSITY

BANOING OF GAANULITES

FAULTS SHOWN THUS

TO ADELAIDE

. GUMERACHA

TO ADELA ie

‘\—

a7}

a Ar

CASTAMBUL ot

Fig. 1

A regional map showing the extent of the Archean inlier.

117

is evident, The only important exceptions to this are certain areas of gneisses

in the Humbug Scrub”. He mentioned a contact between the gneisses and injected

schists and believed “that the augen gneisses may represettt an altered igneous

intrusion changed partly while still in the plastic condition.” Alderman (1938)

made an important contribution to the study of the gneiss and removed any

doubt of their sedimentary nature by showing that the two rock types mentioned

above by Hossfeld are chemically and microscopically similar. However, he

postulated a mechanism for the formation of the atigen gneiss by the injection

of a sodium silicate fluid along the schistosity of the phyllites. Sprigg (1945)

and (1946) dealt extensively with the geomorphology and structure of this area

as part of the Mount Lofty Ranges, but some details of structure are mow being

revised. In a preliminary survey for the South Para Dam site, Miles (1950)

contributed a detailed map of the portion of the unconformity together with

some structural data.

SCOPE OF PRESENT INVESTIGATION

The position in 1949 was that, although all geologists familiar with the

“diorite” doubted its igneous origin, the published work required considerable

revision in view of the rapid advances in geological knowledge in recent years.

With this end in view, work was commenced early in 1949 and completed late

in 1950,

Extensive field work was undertaken and the Archean inlier was mapped

in detail as a whole. This has revealed a complex consisting of schists and

gneisses already accepted as being of a sedimentary derivation, with some rocks

which have been considered magmatic in origin and called diorites, but which

are also highly altered sediments. There is widespread evidence of high-grade

regional metamorphism, although many of its effects have been modified by later

retrograde metamorphism. Further complexities are introduced due to meta-

somatism and by metamorphic convergence of the Archean gneisses and the

sheared basal members of the Adelaide System,

This investigation has been particularly concerned with the genesis of the

“Houghton diorite” which is shown to be a metamorphosed sediment, In this

paper the term grariulite is recommended, and used in place of “diorite” because

of the unsuitability of the latter term to express the true nature of the rock.

STRATIGRAPHY

The area contains rocks of the Archean, Late Proterozoic and Tertiary

age with no evidence of deposition for long periods between them.

There was considerable erosion of the Archean rocks before the sediments

of the Adelaide System were deposited with marked unconformity upon them,

Although this contact is frequently obscured by shearing or soil cover, there are

exposiires at the following places (in addition to those recorded by Miles (1950):

(a) In a creek-bed south of the road from One Tree Hill to the Humbug

Scrub Sanctuary. The actual erosion surface is seen to be overturned

and dips east at about 80°, being stratigraphically overlain by 150 feet

of basal arkoses.

{b) At the Devil’s Nose on the South Para River the unconformity is normal

and dips steeply west.

Williamstown road and the track to the New Deloraine Mine, gneisses

are overlain by ilmenitic sandstones with a Mount Bessemer type

haematite-schist notable, dipping at about 60° to the east,

118

Due to Palaeozoic and Tertiary faulting and soil cover at the north and

south of the inlier it is not possible to find a direct connection between the

ilmenitic sandstones and arkoses to the east and west of the inlier, and Hoss-

feld (1935) assumed that these beds were of different ages. However, in view of

the strong lithological similarities of the sediments on either side of the Archean,

there is no evidence that the basal beds to the east of the inlier are not the same

age as those to the west. Strike faults have disturbed the stratigraphic succes-

sion above the Archean and correlation is possible only in the lowest members.

There is no evidence of sedimentary deposition over the folded Adelaide ~

System until mid-Tertiary, when horizontal lateritic gravels of a terrestrial nature

wete deposited unconformably upon both Archean and Proterozoic rocks. After

later block-uplifts these ferruginous conglomerates remain as small but persistent

patches, usually capping hills.

te pri

f crust. *

i a ae ek en

ZONE Ss «2-8 H

wise st 1 4

shan 7m BCHISTS

wey ' i ! AND ft

~ yt GHEISSES)

ert eser

an"

eeo-t=-

SCALE oO SF 1000 YARDS

Fig. 2

A diagrammatic sketch map illustrating the manner

folding of the granulites.

STRUCTURE

The: production of structures at various periods over the whole range of

geologic time from Archean to Tertiary, gives the area such an involved history

that the problem as revealed in the field is clearer when dealt with on a chrono-

logical basis.

119

AgcHean OroGRNy

The oldest orogenic structures are those ptygmatic folds of the highly meta-

morphosed Archean sediments. Field ohservations of the granulites show folding

which is complex but which may be mapped. Poor exposures and the super-

imposed schistosity, however, tend to obscure the tight isoclinal folds in the

gneisses. These latter folds are only revealed to any extent in the fresh vertical

rock-faces along the Torrens Gorge. The scale of folding differs considerably

in the gneisses and granulites. There are numerous small isoelinal folds with

steeply dipping limbs in the gneisses, but quite large folds in the order of hundreds

of yards across with relatively gently dipping limbs in the granulites,

The banding in the granulites may be treated as bedding and can be mapped

similarly to a normal sediment. Fig. 2 shows a generalized picture of the struc-

ture of the granulites north of Houghton and Inglewood. I[t is not possible to

show more than structural trend-lines as exposures in the field are poor, and

discontinuous overturning of the beds in places has produced a complex fold

system.

There are a series of faults in the metamorphic rocks which are attributed

to the Archean but which differ in age within that period, The order of forma-

tion is suggested by the magnitude and kind of mineralization of the fault zones.

‘The earliest and smallest faults are tightly closed and cut tiny ptygmatic drag

folds, while the next to form are larger and are marked by ilmenite veins up to

six inches across, The last faults to form are largest and the minerals introduced

were quartz and tourmaline. It appears that after the peal of metamorphism had

passed, conditions favoured fracture rather than flow and the rocks were faulted

rather than folded as previously, with the size of the faults increasing as cooling

becarne advanced.

Paragozorc Oroceny

The most pronounced regional structure of the Archean rocks is the schis-

tosity, which is highly developed in the gneisses but only sparsely in the granu-

lites. This schistosity is produced by parallelism of sericite flakes which were

formed by the retrograde metamorphism of the feldspars of the gneisses. It

shows a marked regularity over a wide area and almost invariably strikes at about

170° and dips steeply east. At various places, particularly west of Mount Gawler,

cross folding has caused the strike to swing sharply round, but these variations

are only subsidiary to the general trend. This schistosity is often almost parallel

to the axes of Archean folds but its direction is controlled by a major anticline

in the gteisses formed im post Adelaide-System time. After the deposition of

the Late Proterozoic sediments, there was a great period of orogeny when the

Adelaide System was extensively folded and faulted. This upheaval has been

considered to have occurred during the Cambrian but is here classed only as

Lower Palaeozoic. During this period there was not only considerable folding

of the normal kinds in the Proterozoic sediments but also the gneisses were

thrown up inlo a great anticline, overturned in part slightly to the west. This

is demonstrated hy the normal, moderately dipping unconformity on the east of

the inlicr, with a steeply dipping, frequently overturned contact to the west. A

diagrammatic sketch section is: shown in fig. 3. The regional schistosity of the

gneisses is parallel to the axial plane of this fold and also to the schistosity in

the Adelaide System and is evidently controlled by this period of folding. If

the schistosity of the gneisses had been formed previously to this period then it

would have shared in the folding and would show the form of a schistosity anti-

cline instead of being in a regular regional direction,

120

In certain places on the western side, the basal arkoses have moved con-

siderably over the Archean basement, with the result that the junction has been

obscured due to a pseudoconformity between the older gneisses and the sheared

Proterozoic sediments, Metamorphic convergence between the rocks of different

age has caused the exact margin to become indefinite. This phenomenon is well

shown on the hill south of the Torrens River at Castambul, and at a point

approximately two miles north-east of Houghton near the Lower Hermitage Road.

The direction of the schistosity of the gneisses is attributed to Lower Palaeo-

zoic orogenesis but the mineralogical changes of the retrograde metamorphism: may

have taken place before the deposition of the Adelaide System. This is indicated

by the fact that marked retrograde effects cease sharply where an unsheared

unconformity can be found aid the basal arkoses do not share the breakdown.

WINS

Fro

t 4

SSS

Fig. 3

A purely diagrammatic section indicating the general

Structure in the Archean due to Palaeozoic folding.

Apart from the complex shears of this time, there are the simpler faults and

crush zones which are mineralized with quartz. About one mile north-west of

Gumeracha there is a crush zone approximately half a mile across in which

Archean granulites and schists, together with Proterozoic phyllites, sandstone and

dolomite, become slightly contorted. A little mineralization has occurred as shown

by the presence of quartz, calcite, pyrites and gold. The formation of the major

anticline which caused considerable slip along the western margin of the Archean

inlier, also resulted in a series of parallel strike faults in the Proterozoic sedi-

merits close to the inlier, The major fault in the south-east of the area is con-

sidered by Sprigg (personal communication) to be a Palaeozoic fault re-opened

in Tertiary times.

Just within the southern margin of the Archean are outliers of Adelaide

System sandstone, quartzite and Lower Torrens dolomite, but these are so poorly

exposed that it is not possible to determine conclusively whether they are simply

residual patches left by erosion or are the remains of a thrust sheet from the

south-east.

Tertiary OROGENY

The last stage in the orogenic history is revealed by the fractures of the

Tertiary which appear as numerous fresh unmineralized faults, sometimes of

extremely large dimensions.

These faults show moderately well-dissected scarps. Certain faults show

mineralization (typical of Palaeozoic movement), together with a scarp {typical

of the Tertiary block uplifts). It is considered that such faults originated in

the Palaeozoic and were re-opetied in the Tertiary.

121

‘The striking similarity in the field of the direction of all structural features

points to a regularity in the direction of the orogenic forces in the geosynclinal

basin from Archean to Tertiary times.

SEDIMENTS OF THE ADELAIDE SYSTEM

The Late Proterozoic sediments of the Adelaide System overlie the Archean

with marked unconformity. At the base are grits and arkoses notable because

of cross-bedding shown by ilmenite. In this area, these sediments only show

slight metamorphism in certain localities where they become sheared.

A typical example of the lowest part of the series is shown at locality

{a} on page 117. The series is as follows ;—

150 feet. Basal Grits. These include a coarse, black arkosic quartzite at the

bottom, then a white arkose and white cross-bedded ilmenitic sand-

stones and grits, slightly overturned,

400 feet. Phyllite. A dark micaceous phyllite with some arenaceous and cal-

careoiis bands dipping vertically. A Palaeozoic strike fault occurs

here,

180 feet. Dolomite A dark blue fine-grained rock, possibly equivalent to the

Upper Torrens dolomite. The dip becomes shallower to 50° E.

100 fect +. Sandstone and Phyllite. White sandstone and grey phyllite are cut

off by a large strike fault.

The basal sandstones are typified by the presence of feldspar and ilmenite

and when sheared these minerals form sericite and chlorite, making the rocks

schistose. This process gives rise to low-grade schists at the unconformity and

these sheared basal Adelaide System rocks become very difficult to distinguish

from the Arehean schists.

Rock (8933) is typical of these schists, It is a light-coloured highly

schistose rock consisting of sericite with bands and patches of gteen mica, the

bands being at about 30° to the schistosity. It has a slightly speckled appearance

due to the presence of ilmenite.

Microscopically it differs from the retrograded Archean gneisses in that the

sheared nature is evident and plagioclase relics are lacking, Quartz is abundant

and cracks in it are often filled with sericite in parallel flukes. Leucoxene is

common, while chlorite is present as wisps and patches.

This metamorphic convergence causes the Archean and Proterozoic rocks to

become similar in appearance and thus causes difficulty in field mapping in certain

parts of the area. The southern part of the western margin is particularly obscure

for this reason.

ARCHEAN ROCKS

The Archeatt rocks are classified under two major divisions, the augen

gneisses and the granulites, Both types have associated schists which have

formed by retrograde metamorphism, There is a further minor group referred

to as the transition gneisses which forms an intermediate step between the gneisses

and granulites. The remainder of the rocks are discussed as pegmatites or un-

classified types,

{a) Gneisses , (d) Pegmatites and pegmatoid rocks

{b) Granulites and leucocrats (e) Unclassified types

122

GNEISSES

The “Hembug Serb gneisses” are the predominating type in the area, and

together with their associated schists constitute about 85% of the Archean, They

are rocks with light-coloured qwartzo-feldspathic bands or augen set in a dark

schistose ground mass of seticite and yuartz, and are classified in the held as

banded gneisses and augen gneisses respectively.

The banded and augen varieties merge into each other and Alderman (1938)

has shown them to be chemically similar. In the field the gtieisses appear to have

bands and angen of pegmatitic material which have been forced along the

schistosity of the sericite schists. On this hasis the gneisses were considered by

Alderman to be injected types. Further investigation now shows that

the schistosity of the gneisses was formed later than the process of introduction,

and that the schists now present are the final result of a complex process and are

not the source rocks of the gneisses.

Mineralogically the gneisses consist of microcline with variable amounts of

quartz, much fine sericite (with chlorite and biotite) and only minor amounts of

plagioclase. In addition, sillimanite and garnet occur where the original grade

of metamorphism was sufficiently high and where retrograde effects have not

obscured them. The gneisses outcropping in the southern parts of the area

usually carry one or both of these index minerals or at least show pseudomorphs

of them. These high-grade minerals do not occur north of the latitude of Kers-

brook and the isograd is apparently there.

Typical examples of gneisses taken from widely-spaced areas indicate the

nature and variations within this group.

Rock 8938, from Castambul, is a typical example of the gneisses of the Lower

Torrens Gorge which have reached the biotite grade only. It is a light

grey gneiss, irregular and coarse in grain, with large feldspar phenoblasts up to

3 cms, diam., and smaller quartz crystals enclosed in a fine-grained micaceous

mass of sericite and chlorite. The feldspar is chiefly fresh microcline with a

little much-altered plagioclase (Ab,, ).

The alteration of the feldspars, which is invariably well advanced, has taken

place firstly along cracks and cleavages, and finally large areas are made over

to an aggregate of decomposition products. The process has given rise to small

colourless granules of epidete or to a multitude of tiny colourless sericitic mica

flakes, frequently orientated parallel to the twin planes of the albite. The size

of these crystals does not permit the optical properties of the mica to be deter-

mined but it is presumed to be a potash variety. It may possibly be the soda-

mica paragonite, but as slbite appears to be stable under such metamorphic condi-

tions and forms merely small clear untwitned grains under even the most severe

stress, such does not seem likely. The potash necessary for the production of

sericite within the plagioclase appears to have been held in an unstable solid solu-

tion and has been liberated under stress conditions. In some cases the plagio-

tlase shows alteration around the edges, suggesting an attack by potash liberated

when nearby crystals of microcline were sericitized.

In the more highly retrograded racks the plagioclase ts replaced progressively

by increasing amounts of sericite until there is only a faint skeleton showing

multiple twinning in a highly orientated mesh of fine sericite laths.

The potash feldspar which is present in abundance is invariably microcline

and careful search showed no trace of orthoclase, Cross hatching is frequently

visible, but even those crystals not showing this feature were found to be

triclinic by orienration procedure on the Universal Stage, The feldspar is often

perthitic (see Pl. VIL, Fig, 1) and contains large amounts of albite as coarse

irregular spindles, It appears to be due to an exsolution process from a high-

123

temperature feldspar. Extinction angles from the 010 cleavage do not exceed 12°,

It is noticeable in the hand specimen that the micrécline is white while the plagio-

clase is flesh-coloured,

Quartz ig abundant in all the auger gneisses and occurs as irregular, often

elongated or lenticular crystals showing marked undulose extinction. It is fre-

quently biaxial with a low optic axial angle. The undulose extinction of the quartz

is very well developed and gives an crroneous impression of the amount of shear-

ing which has taken place. One particular quartz crystal showed a difference

of 60° in the extinction positions of its parts by rotation on the stage of the

normal petrographic microscope, but on orientation on the Universal Stage it

was found that all the optic axes in that crystal were parallel, indicating that the

crystal lattice had not been appreciably strained, It has been shown by

Sander (1930) that a quartz crystal in a sheared rock may have differences in

the directions of its optic axes of up to 10°, and it is therefore presumed here

that the metamorphism which has produced such striking features as the strong

undulose extinction in quartz, the biaxiality in quartz and apatite, and a notable

schistosity, has not been as high in shearing stress as ig suggested by early obser-

vations. It is an additional fact that Reynolds (1936) has described similar features

in other rocks, as replacement effects. All available evidence points to large-scale

breakdown of the gneisses by retyoarade metamorphism to a low-grade regional

facies rather than a process of dynamic metamorphism producing sheared rocks.

In some cases the tndulose extinction of the quartz appears to be due to the

recrystallization and welding of several previously unre'ated fragments tending

to produce a larger crystal (super-individual) of uniform nature, and evidence

often suggests a growth in the quartz rather than a fragmentation. There are

examples of true sheated and mylonitized rocks where dynamic stresses have

been high.

Biotite is present in this gneiss as very ragged laths and often as intimate

growths with sericite and chlorite. Ilmenite crystals have been fractured, and

in places iron appears to have been released to form a dark mica as a zone about

the iron ore in a general matrix of sericite-

The schistose portion contains much scricite with biotite, chlorite, ilmenite,

while the accessories are apatite, calcite, zircon and rutile.

In the upper reaches of the Torrens Gorge there are sillimanite and garnet

gneisses, A typical specimen is (8928), a dark-grey rock, massive to gneissic

in texture, with some silky white fibres of sillimanite, small green patches of

chlorite which are pseadomorphic after garnet, and a scattering of pyrites. The

rock possesses the common gneissic texture with large stressed and broken por-

phyrublasts of quartz and microcline in a well-directed schistose matrix. Silli-

manite is present as fresh tabular crystals or in all stages of sericitization.

Optically it is biaxially positive with a low optic axial angle (as low as 5°). The

retrograde process of scricitization of high-grade sillimanite causes the geographical

limits of the sillimanite zone to be very indefinite in the field. In some gneisses,

well inside the sillimanite area, there are pseudomorphs which retain sufficient of

the original form io allow it to be recopmised, but frequently there is 2 complete

obliteration of all high-grade minerals. The production of sericite from sillimanite

is presumed to be concurrent with the sericitization of the feldspars, and is due

to the excess potash liberated by the latter process under low-grade conditions.

A red-brown garnet, apparently near almandine in composition, is less

ahundant. Diapthoresis affects it to a lesser extent than the sillimanite, but it

frequently shows partial or complete chloritization to a green petininite, The

chlorite pseudomorphs are frequently visible in the hand specimen. It is notice-

able that sillimanite and garnet occur together in the Torrens Gorge, hut that

124

garnet alone occurs in the vicinity of Kersbrook. This suggests a series of

sillimanite-, garnet-, and biotite zones towards the north, although the limits

cannot be accurately delineated in the field.

The biotite has an appearance typical of high-grade Archean rocks in South

Australia and occurs in irregular laths, often bent and strongly pleochroic from

a light to a very dark brown. It is frequently riddled with small inclusions of

iron ore or rutile, while in certain specimens it is found interleaved with sericite,

chlorite, quartz or sillimanite,

Pyrites and zircon are accessory minerals, The zircon invariably shows a

perfectly rounded or oval form which is considered to have been due to its

original detrital origin, unaltered by later recrystallization. This form of zircon

occurs in gneisses, schists and granulite alike.

Slight variations in the constituents of the gneisses are found, some being

richer in sillimanite or garnet than others, and some lacking one or both of these

index minerals,

Apatite is a common accessory in the gneisses, and a wide variation in

properties is recorded. It may be colourless or pale brown, with a pleochroism

« >, and has an optic axial angle varying ftom 0° to 40°,

Associafed with these gneisses are bands, lenses and large irregular areas

of light- to dark-green schists, and these are considered to be the ultimate pro-

ducts of the retrograde processes. The schists possess the fine-grained sericitic

divected texture of the gneisses, but lack the latge feldspar porphyroblasts. They

are very schistose and are considered to be the more highly retrograded members

of the augen-gneiss group and are regarded as being phyllonitic, not phyllitic in

nature. For a cortect interpretation of the gencsis of the rocks, it is necessary

to recognise that there are no simple low-grade rocks within the Archean inlier.

Rock (8931) from the Torrens Gorge is typical of this group. It is a pale

green schist of phyllitic appearance with both a banding and a strong cleavage.

It is very schistose, consisting of a fine-grained ageregate of flakes of sericite

with chlorite and quartz, The latter shows granulation and recrystallization in

lenticular groups, elongated in the direction of the schistosity. Colourless sericite

and chlorite may flow around small porphyroblasts of quartz or may grow in

sheafs athwart the fissile direction, A string of rutile grains also cuts across the

schistosity, apatite is accessory,

The schists show their true nature by their association in the field. Irregular

bands up to hundreds of yards in width can be seen in direct contact with high-

grade metamorphic rocks, ¢.g., sillimanite gneisses, Schists in other parts of the

area which appear to be phyllites are identical with these phyllonites,

From a detailed examination, the genesis of the gneisses appears both

indefinite and complex, for nowhere in the area does there occur a rock which

may be regarded as an unaltered parent type,

As far as can be ascertained the original rocks were pelitic. They underwent

regional metamorphism which reached its maximum in the south where sillimanite-

grade rocks occur, while rocks of the garnet and biotite grades occur to the north,

At conditions of high temperature and pressure an introduction of alkalies (chiefly

potash with less soda) took place. This resulted in the formation of soda-

microcline which later unmixed to form a typical coarse high-temperature

perthits. This introduction is considered to have been a “soaking” prosess with

gentle addition and migration of material along previously existing S-planes.

The lack of cross-cutting feldspathic bands and the general uniformity point to a

gradual addition rather than a lit-par-lit “sqitirting™ or injection. It seems most

likely that the microcline was not introduced as such but was formed along pre-

ferred directions where fluxing and recrystallization took place. Orogenesis

125

caused tight isoclinal folding while the rocks were still in the plastic “migmatic”

state. At a later stage, conditions of low-grade regional metamorphism with low

temperature and strong sheating caused a period of retrograde metamorphism

which affected the high-grade rocks considerably, It was at this time that the

widespread regional schistosity now visible was produced by the alteration of

microcline to sericite, Sillimanite became unstable and combined with the

liberated potash to form sericite, while garnet was a little less unstable and usually

became only partly chloritized. ‘The biotite became a less ferruginous variety

and deposited tiny granules of iron ore, The process was by no means uniform

and affected certain areas to a greater degree than others. In some rocks no

traces of original high-grade minerals remain, while in others only slight retro-

grade effects are noticeable. The effects of retrograde metamorphism have been

arrested in all stages and the outlines of the process may be described briefly

as a sequence,

(a) Early results are the cracking and bending of feldspar and biotite crystals

accompanied by a littie sericitization around the edges of microcline and

sillimatiite. Quartz shows undulose extinction.

(b) At @ later stage, the general grain-size is smaller and the very large

porphyroblasts have heen broken up, The processes of sericitization,

saussuritization and chloritization ate wel] advanced. Cracks, cavities and

cleavages are filled with alteration products, Quartz and apatite are

hiaxial,

blasts being quartz, elongated due to flow and recrystallization and with

an optic axial angle of 5°, The high-grade minerals, microcline, plagioclase,

sillimanite and garnct may still persist as vague relics. The rock consists

for the most part of finely-schistose sericite, chlorite and biotite, with clear

granules of quartz and regenerated albite.

(d) The final stage is that of the completely retrograde schists where no high-

grade minerals occur and only tiny porphyroblasts of ragged quartz occur.

GRANULITES

In the south-western and south-eastern portions of the area around the towns

of Houghton and Kersbrook respectively, there occuts a group of distinctive

strongly-banded ctystalline rocks rich in feldspar. Examples of these have been

called the “Houghton Diorite” by Benson (1909) and they were thought to have

heen formed by the metamorphism of igneous rocks crystallized from the

“Houghton Magma”. There has been some doubt in the past as to the origin of »

these rocks, and although they constitute only 15% of the Archean rocks out-

cropping, particular attention has been paid to them,

Qn tiormally weathered faces of the faggy slabs the appearance is often that of a

normal sedimentary rock of quartzitic composition, and only on inspection of a

freshly-broken face does the crystalline nature become apparent. The banding,

which is a strongly-developed and typical feature is remarkable for its uniformity

and parallelism, Bands vary in width from 4-3” and may be followed for 20 feet

without significant variation, this being the longest tinbroken rock face found

(see Pl. VII, Fig, 2). This foliation is due partly to the segregation of coloured

minerals (diopside, actinolite, ilmenite and epidote) im the darker bands, with

quartz and feldspar in the lighter portions, and partly to the fact that retrograde

metamorphism is more advanced in the latter. The banding is considered to be

mimetic after original sedimentary banding and sometimes shows structures

resembling cross bedding.

126

The granulites resemble igneous rocks in their chemical composition, and

different varieties have been described as being of dioritic, syenitic or granitic

nature, The extreme variability of composition ffom acid to intermediate is a

typical feature and the varieties are intimately associated in the field. The most

common rock is a plagioclase-rich quartz-poor granulite with the composition of

a diorite, and this constitutes the major part of both the Houghton and Kersbrook

bodies, Smaller masses of quartz-rich granulites occur in the Torrens Gorge,

The smaller isolated bodies differ from the main masses and outcrop (1) on the

map (Fig. 4) is chiefly a coarse quartz-feldspar-biotite-gneiss which is cut by

AS iis

--y 4

GUMERACHE

ARCHEAN

WYLLER DOK , GRANULITES , LEUCOGRATS.

AESEAVOIN

AUGEN GHEISSES. SCHISTS,

PHYWLONITIC SCHIST,

YATALITE.

PROTEROZOIC

ADELASDE SYSTEM OUTLIRAS,

FAULTS SHOWN THUS /

# oir or stomests # StHISTOSITY A BANDING OF ERAWULITES

a sr

Fig. 4

Map showing some detail of the relations between granulites and gneisses.

occasional barytes veins. Outcrop (2) is rich in quartz and biotite, while micaceous

haematite is abundant in places, There ate additional small pranulite masses

which ate not shown on the map, the largest being seyeral miles notth of

Kersbreat,

127

A granulite from Kersbrook (8935) is typical of those rocks of dioritic

composition and shows palimpsest cross bedding. It has alternate light-coloured

moderately coarsely-crystalline bands, alternating with light-greyish fine-grained

bands, The latter show the cross bedding outlined in actinolite and ilmenite grains

(see Pl. VII, Fig. 3). The bands differ in that the fine part shows cross bedding

and contains quartz, while the coarse parts lack quartz and have less epidote,

diopside and actinolite. The most abundant mineral is plagioclase, andesine

(Abgs),; while actinolite is well developed as closely-packed fibrous bands.

Accessories are epidote, ilmenite and actinolite.

Another specimen, (8942), from Kersbrook has the composition of an

adamellite, It is a light-brown medium-grained rock with elongated bluish

opalescent quartz together with feldspar, biotite and a little epidote. The

variability within these rocks is demonstrated by the fact that in two different

microscope slides cut from the same specimen, one did not contain diopside and

sphene, while the other had 4% of these two minerals. The composition of the

plagioclase and the abundance of biotite also varied considerably. The rock has

a granoblastic texture and consists of quartz, fresh microcline, cloudy plagio-

clase (andesine Ab,,), biotite and diopside with accessory apatite, sphene,

ilmenite, leucoxene and zircon, The composition of this rock is compared with

specimens previously analysed,

TARLE I

“ADAMELLITE” “DIORITE” *“DIORITE”

Anal, Spry Anal, Alderman Anal, Benson

Mawson (1926) Benson (1909)

58-19 56°85

SiO: - - = - - 69-25

ALO, - - - - - 13-40 15-28 14-76

FeOs - - + - = 2-69 1+58 4:48

FeO - - - - - 1-47 1:23 1-21

MgO - - - = - 1-53 3°85 3-89

CaO - - - - - 2-47 8°72. 7°91

NaO- - - - - - 3-03 4°76 5734

-KsO - - - - - 4-66 3-02 1-91

HiO+ - - - - - 0-49 0-16 0-12

HsO— - <a - - 0-16 0°29 0-08

POs - - - - - 0+13 0°48 0-51

MnO - - += = - 0-01 0-05 0-12

TiO, - = - - - 0-91 2°65 3-11

COs - = = - - — _ _

Ba - - - - - Trace — —

Ss - - - - - - Trace _ —_

Total - - = 100-16 100-26 100-32

NORMS

Quartz - - - - - 26-88 2-16 2:54

Orthoclase - - - - 27-80 17-79 11°12

Albite - = - - - = 25°68 40°35 45-06

Anorthite ~ - . - 8-90 11-40 10-84

Dicpside - = - - 2-16 18-38 1469

Enstatite - - - - 2°80 1-00 —

Hypersthene - - - _ _ 2+80

Ilmenite - - - - 1:67 2:74 2-89

Haematite = - - - - 128 1-60 4-48

Apatite - - - - - 0-34 1-34 1°34

Titanite - - - - — 2:94 3:92

Magnetite - - - - 2-09 — —

128

Another rock from the Torrens Gorge is an acid biotite granulite with the

composition of an adamellite, No. 8923, It has the appearance of a light-coloured

gneissic granite with bluish opalescent quartz and black biotite, it consists chiefly

of a coarsely-perthitic microcline with slightly less quartz drawn out in elongated

forms, Biotite is irregularly crystallized and does not show a directed texture

in the thin section, <A little highly-altered oligoclase is present. Accessories are

rutile with much leucoxene and zircon. Although the amount of plagioclase at

first visible is low, close inspection shows that a considerable amount is bound

up with the microcline in the coarse perthite. The rock would thus be classified

as afi adamellite rather than a granite.

A typical specimen from Houghton is (8937), It is a light grey rack with

a fine even grain and has regular bands 1-2cems. wide traversing it, It consists

of moderately large interlocking irregularly-shaped crystals of cloudy plagioclase

with subordinate microcline, diopside and epidote. The plagioclase often shows

effects which are probably due to straining. These are:

(1) bent and warped twin lamellae,

(2) irregular secondary twinning,

(3) utidulose extinction,

(4) peripheral cracking and granulation,

The feldspar is highly altered and the composition could not be determined

by complete orientation procedure on the Universal Stage, and extinction angles

were measured from O10 in the symmetrical zone, This method, however, gave

several anomalies. It was found that even in the zone normal to 010, albite twins

did not extinguish symmettically, This may be due to the warping of the twin

plane which has already been mentioned, or may be due to differences in composi-

tion of adjacent plagioclase twing. Emmons (1935) has noticed that “a very dis-

turbing occurrence of such variations is in adjacent twins which may differ optically

in composition by more than 10%," In these rocks there is an indication of differ-

ences of 5% and this is also suggested by the fact that the degree of alteration

of adjacent twin latnellae often differs also.

This specimen shows the coarse antiperthite which is a common feature of

the granulites. Crystals of microcline are enclosed by a larger crystal of plagio-

clase with the individual inclusions in optical continuity with each other and in

some cases with the host also (see Pl. VIII, Fig. 3), In one instance where both

the host and inclusion are twinned, the similar optical continuity is readily seen.

The 010 direction of the albite twin-plane coincides while the twin-planes of the

pericline twinning in the plagioclase and the microcline twinning in the potash

feldspar are at 54°, indicating coincidence of the 001 direction in both crystals.

This antiperthite is: considered to haye been formed by the replacement of micro-

cline by plagioclase and implies an addition of soda after potash to the granulites.

The pyroxene which is present in most granulites and which is abundant

in this rock is a pale green diopside. Occurrence of the fresh unaltered mineral

is uncommon, and usually the pyroxene is rimmed or entirely replaced by a

pale green fibrous uralitic actinolite. The diopside indicates the high grade reached

by the rocks and also suggests that the original sediments were rich in lime and

magnesia,

Epidote occurs both as the pleochroic yellow variety in large crystals, and as

tiny colourless granules formed by saussuritization of the plagioclase.

Apatite is an accessory and js brown and pleochroic with an optic axial angle

of 40°. Epidote is frequently associated intimately with it. Black opaque grains

oi ilmenite have pale green actinolite growing around them.

129

Rock (8936) from Houghton is closely similar to the generalized description

above antl is notable because of abundant tiny colourless to pink or blue euhedral

prisms of tourmaline included in the plagioclase. Many of the granulites show

this fealure.

There is a variety of granulite which outcrops south of the Houghton

cemetery and which has been described as an “ophitic diorite’, In the hand

specimen of a moderate fine-grained rock a poikiloblastic texture is visible where

the plagioclase includes granules of diopside. The gramulite is a greenish rock

with a very fine banding due chiefly to diopside grains, It consists chiefly of

oligoclase-andesine (Ab,,,) with diopside and microcline and lesser amounts of

sphene, epidote and apatite and a little quartz, The extreme variability in com-

position is shown by modes of three slides cut Irom the same hand specimen.

An analysis by Alderman is given in Table I. This specimen was previously

called a monzonite by Mawson (1926),

Slide 1218 - - - ~ Nol No.2 No.3

Diopside - - - - - 15 30 20

Plagioclase + - = - fet 35 40

Microcline ~ = = - 10 18 23

Sphene ~ = ee 8 9 7

Quartz and accessories - - 7 8 10

The poikiloblastic texture is shown by large crystals of plagioclase with rounded

inclusions chiefly of diopside but also of microcline and quartz, The microcline

has the previously mentioned antiperthitic relation with the plagioclase, while the

quartz occurs as groups of very tiny granules, The poikiloblastic texture is similar

to the coarse antiperthite and is probably due to a similar replacement process.

It is considered that there was a fine-grained aggregate of microcline and diopside

originally and that soda-rich introductions produced a plagioclase by replacement

of the microcline while the diopside remained unaltered. The plagioclase

developed into large crystals and enveloped diopside over considerable areas,

Retrograde metamorphism has not affected the granulites to the same extent

as the gneisses, but mineralogical breakdowns have produced schistose granulites

and phyllonites as lenses and bands within the granulites. The complete break-

down of the crystalline rocks to finely schistose bands of phyllitic appearance

is possibly due to shearing along preferred directions,

Rock (8929) is a schistose granulite from Houghton. It is a dark grey

medium-grained crystalline rock with a distinct banding and a fissility imparted

parallel to this direction by micas. The change from the granoblastic texture

typical of the granulites to the schistose texture of the phyllonites is shown by

the slide which has been cut 30 as to reveal adjacent bands. There are alternate

zones of granulose microcline perthite and quartz with fine-grained schistosc

sericite-chlorite bands. The quartz has undulose extinction while the microcline

shows fracture and peripheral sericitization, In the schistose parts skeletal

crystals of plagioclase showing twinning remain as vague residuals after practi-

cally complete replacement by sericite. There is a considerable amount of white

tnica in cracks and enclosures within the quartz and feldspar as though potash

had entered along cracks and partially replaced the minerals. Biotite is moderately

well crystallized and there is accessory apatite, leucoxene, zircon and ilmenite.

The schists often resemble those derived from the augen gneisses and

rock (8932) is a dark green schist found cutting the granulite in the Torrens

Gorge. lt shows a well-directed highly schistose texture with small porphyro-

blasts of quartz, untwinned albite, rutile, ilmenite and apatite get in a matrix of

green diotite and chlorite with accessory leucoxene and micaceous haematite. The

130

longer growths of green biotite and pale green chlorite are frequently set at an

angle to the schistosity,

Rock (8930) is a pale greem highly fissile rock found cutting the granulites

at Inglewood. It is a fine-grained schistose rock with a foliation due to strings

of quartz porphyroblasts paralle) ta the schistosity which is produced by the

cammon orientation of small lathy of sericite and chlorite. Quartz is plentiful

as clear, colourless crystals with broken and irregular shapes, Caicite is also

present as idioblastic crystals, pale brown and pleochroic, each crystal being

intimately associated with or surrounded by a dark, semi-opaque skeleton of rutile

and haematite. Tourmaline is an abundant accessory as pleochroic brawn prisms

and hexagon sections, with the latter frequently showing a colour zoning with

a pale centre, Pyrites is also a common accessory.

LEUCOCRATIC GRANULITES

The leucocrats are white granulites consisting of quartz and feldspar and

lacking the melanocratic minerals diopside, actinolite, hornblende, epidote and

liotite which are typical of the normal granulites. They are less common than

the grey and green varieties and occur in smaller masses. Outerops may cover a

few square feet or over an acre in area, The chief occurrences are just south of

the Houghton School and at outcrop (3) on the map, while lesser masses occur

south-east of Kersbrook and south of the forrens Gorge. They vary considerably

in grain size and texture, some being almost pegmatitic in appeatance and others

looking like recrystallized arkoses, The granulitic banding iy less prominent and

the most notable directed texture is due to extremely elongated grains of quartz.

These are the rocks which Benson has refetred to as “gnetssic aplites”, and they

are considered to be feldspathized sandstones,

Rock (8924) from the locality (3) mentioned above is very rich in glassy

quartz with only a little feldspar. It is well banded and appears to be a re-

crystallized quartzite with only minor feldspathization.

Rock (8940) from the quarry south of the Houghton school is a pure white

rock similar in appearance to a quartzite. It consists of quartz, andesine and

microcline with accessory muscovite and sphene. The quartz is extremely

elongated and is up to 15 mm, Jong and 1 mm, in diameter, thus giving a pro-

fotinced lineation to the rack. The plagioclase and microcline show the coatse

antiperthitic relationship.

Rock (8939) was taken nearer the Houghton school and differs in that the

quartz is not elongated, but is concentrated in bands of granules in a white

ieldspar-rich rock, The texture is granoblastic and the quartz is mainly in bands

between the main mass of albite (Ab,,) and microcline, which again are sometimes

antiperthitic. There is accessory rutile, muscovite and tiny euhedral tourmaline

crystais. A little crushing and sericitization has taken place.

Rock (8927) is from Kersbrook and is a white fine-grained feldspar tock

with the appearance of a quartzite <A little micaceous haematite is crusted in

joints, The rock consists almost entirely of irregularly shaped interlocking

oligoclase-andesine (Ab,,) crystals, with minor amounts of antiperthitic micro-

cline, biotite, chlorite, sericite, ilmenite and tiny ecuhedral tourmalines, Quartz

is entirely lacking.

The leucocrats appear to have originated under similar conditions to the

normal granulites and differ primariiy because of their original sedimentary con-

‘dition. They contain relatively less lime, iron and magnesia and are considered

to be due to the feldspathization of a pure arenaceous rock.

Like all the high-grade rocks, the leucocrats have been retrograded to some

extent, and phyllonitic schists have been derived from them. North of the

131

Houghton. school the leucocrat becomes increasingly altered until there is an area

of phyllonite which extends for over a mile to the north. Rock (8926) is an

example of this schist. It is a pale grey compact fine-grained rock with scales

of mica adhering to joint faves. Although consisting almost entirely of sericite

it ig not particularly schistose in the hand specimen, and in the field it retains

much of the appearance of the parent granulite, In addition to the finely tmica-

ceous sericite, chlorite and quartz are also present with accessury ilmenite, rutile,

tourmaline and zircon. The rack is due to the complete breakdown of a feidspar-

quartz leucocrat, Benson (1909) noticed this rock and called it an “altered

diorite”’.

While the augen gneisses are generally accepted ag having a sedimentary

origin, the granulites are more open to question and evidence is presented to

indicate that they also are derived from sedimetits rather than being due to meta-

tnorphism of an igneons rock.

(1) The complete heterogeneity and variability of composition, bath mineralogi-

cal arid chemical, points to an addition of material to an originally variable

sediment by metasomatism, If the rocks were igneous then this variability

must be due either to original differences in a complex intrusion or to

extreme metamorphic differentiation, and is not stibstantiated by further

evidence..

(2) The strongly-developed banding is considered to be due to mimetic

crystallization after sedimentary bedding. If the rocks were intrusive

then again a complex process of igneous or metamorphic differentiation

must be postulated. This banding may be mapped in the field and is

folded into strictures identical with those of sediments.

(3) The frequent occurrence of textures which closely resemble sedimentary

cross-bedding outlined in grains of diopside, actinolite or ilmenite are

difficult to explain on an igneous basis.

(4) There are no intrusive contacts between the granulites and the gneisses

and their lack of cross cutting or discordant margins does not support a

process of intrusion.

(5) The granulites merge into the atigen gneisses across the strike through a

zore of transition gtieisses which ate intermediate in properties between

the two types,

(6) There is present a quartz-rich leucocrat which closely resembles a re-

crystallized arkose in its chemical, mineralogical, textural and field pro-

perties. This rocks is an example of an arrested stage in the feldspathization

process which finally produces rocks consisting entirely of plagioclase,

The granulites are considered to have been formed by a process of granitiza-

tion which preferentially altered certain selected horizons in a system of sedi-

ments. “The rocks were probably sandstories and s¢mi-pelites, possibly greywackes

which reached a high grade of regional metamorphism and suffered alkaline

additions (potash first and soda later), together with minor amounts of boron

and phosphorus, There was probably a partial, irregular desilication process, As

the original sediments are not present and retrograde metamorphism has altered

the rocks. since, the mechanism of this early process is in doubt. However, it is

cansidered to have been a gentle replacement, molecule by molecule at approxi-

mately constant volume, so that original structures were not distorted. The

rocks were high-grade gneisses rich in plagioclase and diopside and were folded

while still in the migmiatitic state, Later retrograde changes due to sericitization,

saussuritization and uralitization did not usually affect them as much as the

gneisses. Secondary actinolite, epidote and albite with sericite, chlorite and biotite

are the main retrograde products,

132

The nomenclature of these hybrid rocks is difficult. The original tertn

“Houghton diorite” is misleading, in that it infers both a constancy of composi-

ton and an igneaits origin. The term granulite is used here to imply a meta-

inorphosed sediment, of high grade, rich in feldspar, with quartz {when present)

typically elongated.

In general the granulites are rich in oligoclase and are poor in quartz, The

application of the anorthite content of the plagioclase as an indication of the meta-

morphic grade or facies was not attempted, as the lack of equilibrium between the

minerals in the rocks is everywhere evident, It is a striking fact that the granu-

lites, which are chiefly composed of feldspar and which consequently appear free

from any directed texture (apart from the foliation) show a high degree of pre-

ferred orientation in the optical directions of the feldspars even with a brief

petrofabric analysis.

TRANSITION GNEISSES

A group of banded schists and gneisses is exposed in the Torrens Gorge in

the zone between the pranulites and angen gneisses. The amount present ts small,

there being a width of about 100 yards to the west and perhaps half-a-mile to the

east of the granulites, but the rocks could not be found further to the north. The

rocks combine some of the characteristics of both the granulites and augen

gneisses and show the gradual change from one type to the other. The transition

gneisses may be rich in quartz and have feldspar augen, being similar to the augen

gneisses, but may contain hornblende and epidote which are typical of the

graniulites.

No. 8934 from the Torrens Gorge is a typical specimen, It is a dark green

gneiss with small augen of feldspar set in a fine schistose matrix of hornblende.

Microscopically the rock consists of bands rich in hornblende or plagioclase and

these are the only constituents of any importance. The plagioclase is

andesine (Abg,) and is extremely altered. The amphibole is a fresh bright

green-brown hornblende and while occasional crystals occur in the granulites,

none was found in the true augen gneisses. A colourless tremolite is invariably

associated with this hornblende and grows around the green crystals in perfect

optical continuity, The two minerals have the same extinction angle from. com-

mon cleavages and have similar optical properties. The junction between the

coloured and colourless. amphibole is sharp, Accessories in this rock are epidote,

calcite, sericite, ilmenite and zircon,

There are frequent bands of fine-grained schists cutting the gneisses. There

are compact, dack green rocks with poorly developed augen and directed texture,

No, 8925 is a fine-grained aggregate of ragged crystals of hornblende with tremo-

lite together with extremely altered plagioclase, biotite, epidote, apatite, ilmenite,

calcite and quartz.

A specimen, No, 8941, occurs as narrow bands cutting the granulite in the

bed of the Little Para River north-east of Houghton. It is a soft green schist

composed chiefly of amphibole and is cut by white bands of calcite. It is strongly

schistose with the cleavage set at a high angle to the compositional banding shown

by calcite. The minerals are fresh and well crystallized and the rock consists

chiefly of amphiboles, micas, calcite and quartz with accessory upatite, epidote,

leucoxene, ilmenite and micaceous haematite. There are ragged green biotite

crystals and pale-green penninite present. Ilmenite is seen to be breaking down

ta leucoxene and micaceous haematite,

Evidence suggests that the original sedimentary composition was between

that of the gneisses and the granulites and that they shared additions of soda

with the latter, The effects of retrograde metamorphism are difficult to deter-

mine in this group as primary and secondary minerals are usually indistinguishable.

Vol. 74, Plate VII

‘ABIOL) SUIIIOT, 9} Ul SSIaUT URBAYDIY ayy WI suOTsOIuOD “SUO] Sayaut InoOf st waluisads ayy “Burppaq ssoso

- ‘'Slq jusiedde Buimoys YOosqsiay Woy aypNuesd Sop, VW

¢ sty

*SSOIDE Jody UB} ylodR sl ddR}Y YOOA YT

UOTYANOF, Jeau Surpueq daytpunuesry

ta ais | “‘THQUIRISE?) je ssiaus Urayoty 3atf{y ul SMONAOJUOT)

T ‘Sy

74, Plate VITI

Vol.

Aust., 1950

Soc.

Trans. Roy.

‘S[ODILL Passos

“XCE VONRITPIUDE PY

SUF Kop es yaa ey

‘redspjay jo uonezniowas

“BLOITU passoury

‘S[OD1U passoty)

AOE MONEE py

SHY Wadyuer yuauaseEdet ssir05y

‘x og uonRsy LUBR JA

‘apy yaad - ayiqye - aulpaorot asaR07

133

PEGMATITES AND PEGMATOID Racks

Apart from the simple quartz-microcline pegmatites which are extremely

common in the area, there are also a variety of rocks which have some of the

characteristics of the pegmatites and may be related to them, There are complex

plagioclase rocks which approach the leucocrats in appearance, but most difficult to

explain is the rock which Benson (1909) termed “yatalite”, He described it as “a

coarse-grained pegmatite, composed of uralitic actinolite (after diopside), albite

containing microcline, titaniferous magnetite, sphene and quartz.” It occurs in

narrow bands and veins near Houghton but is most notable in a very large out-

crop which is shown on the map south-east of Kersbrook. Here it occurs as a

lenticular mass several hundred yards long, surrounded by the normal plagioclase

granulite, and consists of extremely coarsely-crystalline actinolite and ilmenite.

The amphibole occurs in dark-green masses several feet across. If this was

intruded as a large pegmatitic body, it would suggest that the diopside and

ilmenite in the granulites had been introduced into the sediments, and so the

yatalite is considered to be a segregation of excess basic minerals displaced by

the process of granitization,

UNCLASSIFIED TYPES:

There are a few minor outcrops of rocks of little importance but of passing

interest in the area, These include the haematite schists of Inglewood and

Castambul, the haematite quartzite north of Houghton, and the quartz tourma-

line schist of the Humbug Scrub.

DISCUSSION OF THE MAPS

This paper is concerned with Precambrian rocks, and the Tertiary gravels and

Recent alluvial deposits are not shown on the maps. It is not possible to show

certain lithological boundaries accurately due to cover by later deposits. The

contact between Archean schists and Proterozoic sheared arkose is in many

places difficult to recognise because of the similar appearance of the two rocks.

The boundary between the granulites and augen gneisses may be quite sharp in

one locality while there may be a zone of transition gneisses and schistose granu-

lites which make the limits of each type indefinite in another place, The

boundaries between these two rocks in the Torrens Gorge may only be placed

approximately for this reason,

ACKNOWLEDGMENTS

This paper was prepared during the tenure of a Commonwealth Research

Scholarship, The author wishes. to thank Professor Sir Douglas Mawson and

other members of the Staff of the Department of Geology for their assistance

in the completion of this work.

BIBLIOGRAPHY

Aupeeman, A. R, 1938 “Augen Gneisses in the Humbug Scrub Area, South

Australia.” Trans. Roy. Soc. S. Aust., 62

Benson, W. N. 1909 “Petrographical Notes on certain Precambrian Rocks of

the Mount Lofty Ranges, with special reference to the Geology of the

Houghton District.” Trans, Roy, Soc. S, Aust., 33

Brown, H, Y. L., and Woopwoop, H. P, 1885 “Geological Map of Barossa and

Para Wirra.” Parliamentary Paper, No, 178, S. Aust.

134

Emmons, R. C. 1935 “The Universal Stage.” Geol. Soc, Amer, Mem. 8,

pp. 151-152

‘Encianp, H. N. 1935 “‘Petrographic Notes on Intrusions of the Houghton

Magma in the Mount Lofty Ranges.” Trans. Roy. Soc. S. Aust., 59

Hossretp, P. S, 1935 “The Geology of Part of the North Mount Lofty

Ranges,” Trans. Roy. Soc. S. Aust. 59

Howcuin, W. 1906 “Geology of the Mount Lofty Ranges. Pt. II.” Trans.

; Roy. Soc. S. Aust., 30

Mawson, D 1926 “A brief Résumé of present knowledge relating to the

Igneous Rocks of South Australia. Rept. Aust. Ass. Adv. Sci., 18

Mites, K.R. 1950 “Geology of the South Para Dam Project.” Dept. of Mines

Bull. No. 24

Reynotps, D. L. 1936 “Demonstration in Petrogenesis, Kiloran Bay, Colonsay.”

Min. Mag., 24, No. 155

SaNnvER 1930 “Geftigekunde der Gesteine,” pp. 173-180

Spricc, R. C. 1945 “Some Aspects of the Geomorphology of Portion of the

Mount Lofty Ranges.”. Trans. Roy. Soc. S. Aust., 69, (2)

Spricc, R. C. 1946 “Reconnaissance Geological Survey of Portion of the

Western Escarpment of the Mount Lofty Ranges.” - Trans. Roy. Soc,

S. Aust., 70, (2)

VOL. 74 PART 2 DECEMBER 1951

TRANSACTIONS OF

THE ROYAL SOCIETY

OF SOUTH AUSTRALIA

INCORPORATED

ADELAIDE

PUBLISHED AND SOLD AT THE SOCIETY’S ROOMS

KINTORE AVENUE, ADELAIDE

Registered at the General Post Office, Adelaide,

for transmission by post as a periodical

SOME NEW AND LITTLE-KNOWN SHORE-BUGS (HETEROPTERA-

SALDIDAE) FROM THE AUSTRALIAN REGION

BY G. D. RIMES

Summary

This paper describes four new species of Saldidae — Pentacora leucographa, Saldula coorongensis,

S. brevicornis and S$. psammobia — which inhabit the shores of salt-water lakes and estuaries, or the

banks of sandy creeks, in South Australia. Descriptions are given of the eggs and five immature

instars of each new species.

135

SOME NEW AND LITTLE-KNOWN SHORE-BUGS (HETEROPTERA-

SALDIDAE) FROM THE AUSTRALIAN REGION

By G. D, Rrmes*

[Read 9 Nov. 1950}

SUMMARY

This paper describes four new species of Saldidae—Peniacora leucographa,

Saldula coorongensis, S. brevicornis and §. bsammobia—which inhabit the shores

of salt-water lakes and estuaries, or the banks of sandy creeks, in South Australia.

Descriptions are given of the eggs and five immature instars of each new species.

In the laboratory all species were successfully reared in air-tight containers,

the bottom of which were covered with damp blotting paper. They fed readily

on dead Drosophila adults. Eggs were laid under the surface of the blotting

paper and the young were removed as they hatched. This was necessary to

prevent them preying on unhatched eggs. All instars of all species are pre-

daceous. The processes of mating and copulation are described. In the field the

eggs of P. leucographa and S. psommobtia are laid into the stems of samphire

plants and this probably applies to S. coorengensis also but has not been observed.

The characteristics of all known Australian genera are described, together

with a key for their identification.

INTRODUCTION

Only four species of Saldidae have been previously recorded from the Aus-

tralian region: Acanthia reuteriella Kirkaldy 1899 and Acanthia cygni Kirkaldy

1899, both fresh-water forms from Western Australia; Acanthia salina Bergroth

1893, from salt-water pools, Admiralty Gulf, N. W. Australia; and Salda

nichalsoni Hale 1920, from Wentworth Falls, New South Wales. This present

work has added three new species of Salduia, and one new species of Pentacora.

Observations of their ecology and biology have been made, including the descrip-

tion of a complete life cycle.

The author wishes to acknowledge his indebtedness to Mr. D. C. Swan,

Entomologist, Waite Agricultural Research Institute, and Messrs. H. Womersley

and G. F. Gross of the South Australian Museum, for advicé and guidance

during the preparation of this work. Ail new material described herein is lodged

in the South Australian Museum,

Key To Tare AUSTRALIAN GENERA

1, Membrane with five areoles - - - - - FPentacora Reuter

Membrane with four ateotes - - 2

2, Membrane with base of inner areole extending m more than two-fifths of its length

base of secand areole = - ald= Fabricius

Membrane with base of inner areole extending tess than two- fifths of its length

beyond base of second areole = - - Saldula Van Duzee

Pen tacora Reuter 1912

Pentacora Reuter, 1912, Of Finska Vet. Soc, Forh., xiv, Afd. A., No. 12, pp. 7-10,

Orthotype P. signoreti Guer.

Body oblong. Eyes converging slightly towards the front. Ocelli slightly

distant or nearly touching. Rostrum reaching middle coxae. Second segment of

* University of Adelaide.

Trang. Roy. Soc. S. Aust., 74, (2), Dec. 1951

136

antenna equal in length to width of head or distinctly longer. Pronotum narrow-

ing moderately towards front, base wide, sides explanate, lateral margins rounded

strongly towards tip or forming distinct angles. Callus not attaining lateral

margins; a transverse impression behind middle of callus, Scutellum wider than

long, bearing a transverse impression, Hemielytra distinctly punctate, often

densely so and for the greater part bearing bristles, On corium the interior vein

bifureates towards. tip, the branches reaching suture of the membrane. Mem-

brane with five complete oblong areoles, the first or inner produced shlghtly

beyond the base of second, its tip not attaining tip of second. Last sternite in

female reduced, not covering genitalia. Hind tarsal segments unequal, the third

somewhat shorter than second. Genotype:—Acanthia signoreti Guer.

Acanthia salina Bergroth 1893, should rightly be placed in this genus, on

Bergroth's description of the membrane (“membrana cellulis quinque completis

instructa’”), The two Australian species may be separated as follows:

Ist and 4th antennal segments equal in length ~ FP, salina Berg., 1893

Ist and 4th antennal segments unequal in length, ie, 4th antennal segment two-thirds

longer than Ist - - - - - - - FB. leucographa sp. nov.

PENTACORA SaltNa Berg., 1893

Acanthia salina Bergroth, 1893, Ent. Mon. Mag., 29, 279.

Salda salina Hale, 1924. Proc. Linn. Soc. N.S.W., 49, (4), 466.

Oval, dark-coloured, covered above with very dark hair, head, pronotum and

scutellum shining, Hemielytra opaque, Spot on sides of pronotum narrowly

continuing forward and behind to following margin. Posterior Jateral edges of

seutellum forming a V-shaped sign apically with the hind band of clavus, There

is a median spot and a spot near the internal angles of the corium. Edges of

acetabulum and posterior edges of metasternum and apical margins of yentral

sepmients, legs and often frons slightly golden. Femora, except tip, and tip of

tarsi black, Head (with eyes) distinctly wider than apex of pronotum, pronotum

long medially, Frons with oblique black impressed line on each side, Antennae

similar in colour, and in adult, first segment diametrically opposed seen unequally

from above and provided with spurs unequally protruding; second two and one

half times longer than first; third half as long again as first; fourth one-third

part shorter than third. Pronotum and scutellum like soft leather, edges raised.

Hemielytra not projecting beyond tip of abdomen. Corium and clavus clearly

punctulate. Membrane with five complete cells which are dark and smoky with

dark veins, Hind tibia and tarsus dark and spinous,

Pentacora leucographa sp. nov.

Holotype Male—Eyes prominent. Head, including eyes, distinctly wider

than anterior of pronotum, slightly brownish, with inner edges of the eyes devoid

of facets. Deep cleft between ocelli and eyes, gradually diverging from level of

ocelli and meeting eyes half-way along their inner margins. Between eyes and

this cleft is a raised light-coloured patch. At the posterior tip of this raised patch

isa jong bristle. Frons bearing a pair of bristles at its anterior edge and another

pair half-way between these and the ocelli. Occlli slightly raised, almost con-

Higuous, dark orange. A pair of large bristles one-third of the distance from the

ocelli to the neck and separated by a distance equal to the width of the ocelli.

Rostrum dark-brownish, shining and extending beyond middle of hind coxae.

Antenna with first and second segments whitish, with short black bristles. Third

and fourth segments dark brown with short pubescence and a few long bristles.

Total length of antenna 2°51 mm_ Ratio of segments I; IT; III; IV:

15:35:25; 25, Ratio antenna to body length ts 71: 100,

137

Pronotum shining black with silver pubescence, lateral edges straight with

large white patches extending nearly their entire length. Strongly convex callus

extending two-thirds of length of pronotum. Fovea placed well in front of

middle of callus; also two very slight depressions on each side about one-third of

the distance from central fovea to lateral edge of callus. Scutellum shining black

with short golden pubescence and very marked contours (fig. 1), the posterior

half with transverse striations. Scutellum and pronotum with a few long bristles,

Fig. 1

Saldula psammobia—A. to E, variation in membrane venation; F, Male antenna;

G, Female antenna; H, Egg; I, Surface of egg; J, Stem of samphire (Sulicornia sp.)

with eggs inserted; K -N, Parameres. K, Pentacora leucographa; 1, Saldula cooron-

gensts; M, Saldula psammobia; N, Saldula brevicornts.

Clavus dull black with sparse, short, black pubescence and a few black

bristles. A long white patch extending centrally in clavus for the posterior third

of its Iength. Corium dull black with very spare short black pubescence and a

few black bristles, A large white patch mid-way on outer edge of corium; also

one at anterior and extending back along the inner edge narrowly for a greater

or lesser extent. Coritm with one median longitudinal vein bifurcating at its

distal end, and a cross vein extending from point of bifurcation to embolium.

138

Emboltum for the greater part shining black; posterior third dull black with

sparse black pubescence, .A whitish transparent patch opposite anterior white

patch of corium. Also an opaque white patch at posterior end, extending the

whole width of embolium. Membrane usually opaque and shining, but may be

dull, brownish, Veins black and distinct with a few short black hairs. Outer

edge of membrane dull black, with short black pubescence extending as far as

tip of filth areole,

Ventral surface shining black with short silvery pubescence. Prosternal

area: propleura mostly white, portion of xyphus surrounding coxae white. Meso-

sternal area; sternal area surrounding coxae of mid-leg white, postetior edge

of epimeron white. Metasternal area: posterior edge of metasternum white,

stb-coxal flange white, Abdominal sternites shining black with short silvery

pubescence, posterior edges whitish. Proximal end of coxae whitish, distal end

brown. ‘Tibiae whitish, inter surface with dark band running its whole length.

Distal tip of tibiae dark brown, Second and third tarsal segments in hind leg

differing im length, third being one-sixth shorter than second; first and third

blackish, second white, Combined length of the hind femur, tibia and tarstis

equal to body length, with proportions respectively of 31:50;19, Male length

3°50 mm.; width 1-4mm. Female slightly larger than male: length 3-90 mm.;

width 1-7 mm, Last abdominal segment truncate (typical of genus, see fig. 1).

Antennal proportions different from male. Of a total length of 2°86 mm. the

proportions of the segments are I; 11: TI1: IV: 14:42:22: 22.

Type tocality—Port Adelaide River Basin, South Australia,

The fourth and fifth vein in some variants of P. lewcegraphu may closely

approximate or actually coalesce for a greater or lesser part of their length. One

variant (see fig, 2e) has the veins fused completely for their proximal half, so that

the fourth areole is much shorter than the third and fifth which are contiguous

for a greater or lesser distance basally. This is of interest as it is the typical

wing venation of a separate genus, Chiloxanthus Reuter,

The genus Pentacora has pteviously only been recorded from North America.

The discovery of this Australian species shows that the genus may be much mort

widely distributed than has hitherto been suspected.

SaLpa Fab., 1803

Salda Fabricius 1803, Syst. Rhyne. 113. © Orthotype S, fitteralis (Linn)

{= S. sosterae (Fab.).

To the references cited by Yan Duzee 1917 may be added Saunders 1892,

Distent 1904,

Body broadly oval or oblong oval in macropterous forms. Head deflexed,

narrowing’ slightly towards front, Odcelli together, Rostrum reaching middle of

hind coxae or a little beyond. Antennae slender, with short pubescence and a

few long bristles. Second segment from two and a half to three times as long

as first, Pronotum narrowing strongly towards front, apical margin slightly

narrower than head; sides straight or rounded, Callus large, extending to three-

fourths of width of pronotum. Base of pronotum widely emarginate. Scutellum

wider than long, base plainly visible and always a transverse impression from the

base. Hemielytra variably punctulate, always without silky black patches.

Corium with veins joining, sometimes very slender or absent, interior vein bifurcat-

ing at its distal end, the bifurcations reaching the membrane. Embolium totally

black. Membrane showing four complete areoles, base of the first or inner

areole extending two-fifths or one-half beyond base of second, the apex also in

the macrapterous forms placed above the apex in this way. Apex of secorid

areole not extending further than apex of third. Membrane often abbreviated,

Wings for the greater part abbreviated or absent, Hind tarsal sepments unequal

in length, Last ventral segment in the female roundly produced. Genotype—

Acanthia litteraks Linnaeus.

SALDA NicHoLsONI Hale, 1924

Salda wicholsont Hale, 1924. Proc. Linn, Soc. N.S.W., 49, 465, pl. xlviii,

fig. 4a-d.

S. nicholsoni is the only authentic species of this genus yet recorded from

Australia, being a fresh-water form collected from the base of a waterfall at

Wentworth Falls, New South Wales.

Both Aconthia reuteriella Kirk. and Acanthia cygni Kirk. have been referred

to as species of Salda by Hale (1924). As their descriptions give no clue to

their generic identity, these species must be re-examined before designation to

a genus, Both are fresh-water forms from Western Australia, Kirkaldy in his

description of 4. reuteriella says, “Posterior tibiae nearly three times as long

as tarsi, first tarsal segment one-fifth longer than the second, which is twice as

long as the large falciform claws,” Apparently Kirkaldy has mistaken the

numbers of tarsal segments, three being present in all Saldidae, the first being

very short compated with the second and third which are nearly equal.

SaLpuLa Van Duzee, 1914

Saldula Ms Duzee, 1914.a, San Diego Nat. Hist. Soc., 2, 32; 1914b, Can. Ent,

46, 387.

Acantha Reuter 1895, Acta Soc. Sci. Finn., 21, (2), 5-9. Reuter 1912, Ofv.

Finska Vet. Soc. Forh., liv. 14, (7), 71-72; idem (12), 8, 14.

Body oblong-oval, brachypterous fotms obovate. Head subvertical, Ocelli

almost contiguous. Rostrum attaining middle of intermediate or hind coxae.

Antennae slender. Base of pronotum emarginate, sides straight or rounded.

Callus not reaching lateral margins, but extending behind middle of pronotum.

Scutellum wider than long, and bearing transverse impression. Hemielytra often

with silky black spots. Corium with interior vein bifurcating towards tip, the

branches reaching margin of membrane, Membrane showing areoles, spread

out or abbreviated to a greater or lesser extent; if abbreviated, it nevertheless

teaches tip of abdomen. Base of first or inner areole extending above base of

second but not further than one-third its length. Apex of first areole reaching or

nearly reaching apex of second. Third tarsal segment of hind leg shorter or

longer than second. Last ventral segmen of female roundly produced. Geno-

type—Acanthia saltatoria Linn,

This is by far the largest genus in the family, and specimens of two other

species besides those listed below have come to my notice, one from Launceston,

Tasmania; and one from Viyonne Bay, Kangaroo Island, South Australia,

Key to New SPEcIEs

1. Combined length of femur, tibia, and tarsus, shorter than body length

S. coorongensis sp, tov,

Combined lengih of femur, tibia, and tarsus equal to body length - . - 2

2. Second antennal segment one-third longer than the third - §. brevicornis sp. nov.

Secand antennal segment only slightly longer than the third - S. paammobia sp. nov.

Saldula caorongensis sp. nov. (fig. I, L)

Holotype Male—Head, pronotum and scutellum shining black, covered with

short golden pubescence. Embolium for the greater part shining black with

140

golden pubescence. Corium and clavus dull black, not shining, having grey

patches; also bearing golden and black pubescence. Membranes without

pubescence.

Eyes prominent, slightly brownish, with the inner edges deyaid of faccts.

At junction of eyes with notocephalon a slightly raised, circular, light brownish

area bearing a long brsitle, approximately ten times length of body pubescence.

This area is the same size as the ocelli but not quite as spherical. Ocelli, almost

contiguous, orange brownish, their approximating edges joining a raised portion

of head. Frons bearing two pairs of long bristles, one pair near anterior margin,.

second pair half-way between these and ocelli. Two deep cletts diverging from

ocelli and passing forward to anterior edges of eyes, Region of head behind

ocelli without pubescence and deeply pitted. Rostrum light brownish, reaching

mid-coxae of hind legs, Third and fourth segments of antenna thickly pubescent,

with a few bristles; total length 1-58 mm., the ratio of segments is: 1; II;IU:

IV: :18: 31:25:26, Antennae reach to “46 of distance from front of head to.

tip of hemielytra. Pronotum shining black, bearing short golden pubescence.

Callus extending slightly behind middle of pronotum; with a distinct fovea

slightly in front of centre and a very slight depression one each side about one-

third of distance from fovea to lateral edges of callus. Lateral edges of pro-

notim rotinded. Scutellum shining black with short golden pubescence with

very marked contours. Posterior half bearing transverse striations, Clavus, dull

black, sparsely pubescent, with a whitish grey spot at posterior inner end, just

behind apex of scutellum. A cross vein joins junction of this bifurcation with

margin of embolium. Inner areole of corium dull greyish, with both black and

golden pubescence, Anterior outer areole bearing a whitish patch at one half of

its Jength from anterior end, and one at its posterior end, but chiefly black with

greyish patches, and with both black and golden pubescence. Posterior outer

areole dull black with golden pubescence, Posterior central areole greyish, There

may or may not be a whitish patch opposite to that of corium; also a whitish

patch at hinder margin of embolium with membrane extending whole width of

embolium, or divided into an inner crescentic patch and an irregular outer patch.

Membranes opaque, with irregular blackish and whitish patches; veins black,

bearing a few short black hairs; outer margin of membrane black with short black

pubescence and a whitish patch at its mid-point, Ventral surface of body black

and shining, with short golden pubescence, posterior edge of each sternite yellow-

ish. Femur with a series of brown spots along its whole length. Wind tibia

slightly curved and bearing heavy bristles. Second and third tarsal segments

equal im length, Combined length of bind femur, tibia and tarsus “85 of body

length. Proportions of femur: tibia: tarsus 32:47:21.

Length 3°47 mm.; width 1°6 mm.

Allotype Female—Length 3°80 mm.; width 1°80 mm. Ovipositor prominent.

Last ventral segment roundly produced. No sexual dimorphism in antennal

merasiirements,

Type locatity—McGrath’s Flat, Coorong, South Australia.

Saldula psammobia sp. nov.

Holotype Male—As tor S. corrongensis except for dimensions and body

pubescence; the latter slightly longer and more sparse than in S. coorongensis.

In 4 total length of 1°74 mm. proportions of antennal segments are 1: 1J; III;

TV }:15:30:27-5:27°5, Antennae reaching ‘59 of distance from front of head

to tip of hemielytra. Combined length of hind femur, tibia and tarsus equal in.

length to body, Length of male—2°97 mm,; width 14 mm.

141

Allotype Female — Slightly larger than male. [Length 3°38 mm; width

1:7? mm, Ovipositor prominent. Last segment ventrally produced. Marked

sexual dimorphism of antennae, Antenna length 1:90 mm. the ratio of I; IL; III:

{V-:16- 32:26:26. This sexual dimorphism is very striking, the second seg-

ment of the antennae in the male being only slightly longer than the third, while

in the female it is one-fifth longer.

Type locality—Port Adelaide River Basin,

This species shows considerable variation in wing venation and also in length

af body pubescence. A continuous series of variants can be taken showing grada-

tion from the typical four-celled membrane to a much reduced three-celled stage.

The reduction occurs by the coalescing of the first and second vems. The veins

themselves may vary from a definite black type to a hazy indefinite form scarccly

distinguishable from the membrane itself, A cross vein may rarely be found

extending across the third areole dividing it into two complete cells. As can he

seen from the accompanying figure, the variant with the reduced inner areole has

a much smaller membrane, the yenation of both membranes clearly showing when

the insect is at rest, no overlapping occurring as in the normal individual, This

is the brachypterous form which is figured in the text. Variation also occurs in

the length of the body pubescence in general appeardnce from the normal

individual,

Saldula brevicornis n. sp.

Holotype Male—Head, pronotum and scutellum as for S. coorongensis, but

the surface of the scutellum and pronotum are slightly irregular, having numerous

closely placed small depressions, Antennae with third and fourth segments much

darker than second and with thick pubescence and few short bristles; first and

second segments without this pubescence but with numerous bristles, Antenna

length 1:47 mm.; ratio of segments [: IT: 111: 1V:1 16: 32: 25+5:26°5, Antennae

reach to *46 of distance from front of head to tip of hemielytra. Clavus very

dark brown, very slightly shining, and with short golden pubescence, whitish spot

at posterior inner end just behind apex of scutellim. Corium with venation as

in S. coorengensis. Similar in colour to clavus,-with golden and black pubescence,

Outer edge of corium with a white spot half-way from anterior edge to cross

vein, also a smaller white spot just anterior to this cross vein. Posterior outer

tip of corium with a light patch. Embolium similar in colour to corium, bearing

golden and black pubescence, A whitish transpatent patch opposite the anterior

patch of corium extending the width of embolium and becoming, at the outer

edge, one quarter the length of the embolium. Also a whitish patch at hinder

margin of embolium, with membtane extending whole width of embolium, or

more usually divided into a crescentic inner patch and an irregular outer patch.

Membrane with four areoles, transparent. Veins black and definite, bearing a

few short black hairs, Outer margin of membrane dark brownish with short

black pubescence and a whitish patch at its mid-point. Ventral surface of

abdomen black or dark brownish with short golden pubescence. Legs whitish

and transparent except for last tarsal segment and distal end of tibia and junction

of tibia and femur which are dark brown. Combined length of femur, tibia and

tarsus equal in length to the body, of relative proportions 31:49:20. Second and

third tarsa) segments equal in length.

Length 3:22 mm., width 1-45 mm,

Allotype Female — Slightly larger. Length 345 mm.,, width 1°62 mm.

Type lwcality—Wilson, South Australia, -

142

ECOLOGY

PENTACGRA LEUCOGRAPHA

This species has been collected throughout the Port Adelaide River area and

inhabits tidal areas bearing samphire, and salty marshes. The area north of

Adelaide has been inspected as far as Port Wakefield and, although no specimens

were collected, this was probably due to inexperience or seasonal fluctuations.

These insects move in short, rapid jumps of as much as eighteen inches and are

difficult to detect as they usually occur along with shore flies, which they resemble

in size.

SALDULA PSAMMOBIA

This species is restricted to the same localities and habitats as P, leucographa,

Although it is sympatric with the latter there is a marked difference in their

seasonal yariation, P. Jeucographa disappearing entitely during the winter months

from March onwards, the eggs apparently being the overwintering stage, while

S. psammobia occurs until August, although gradually falling off in numbers after

March. It is highly probable that further collecting will show this species to be

present along the shore of St. Vincent Gulf, north of Adelaide, as there are

numerous suitable localities and no apparent ecological barriers,

SALDULA BREVICORNIS

This species has been collected from Mount Serle, Flinders Ranges, to

Wilson, South Australia. It inhabits the borders of pools and streams, Specimens

have also been collected at various points along the River Murray, at Adelaide,

and throughout the southern Mount Lofty Ranges. As there is a suitable net-

work of rivers extending throughout the northern parts of South Australia and

also into the eastern States, the distribution of this species should ultimately be

shown to be fairly extensive,

SALDULA COORONGENSIS

This species has heen collected in the Coorong, South Australia, from

Kingston (South-East) to Lake Alexandrina. It occurs along the water margins

where samphire is growing but is in greatest numbers at the junction of the

samphire areas with the grass-bearing soil margins, and apparently breeds

throughout the whole year, all instars being readily collected in mid-winter.

The fact that the ranges of distribution of S. psammobia and S, coorongensis

were allopatric by a distance of only 50 miles, necessitated experiments to deter-

mine if they would interbreed, No interbreeding was found to occur.

BIONOMICS AND DESCRIPTION OF IMMATURE STAGES

So far as is known, all members of the family are predaceous. Saldula

Psommobia appeats to feed chiefly on shore flies, All instars, feed on larvae near

the surface of the sand and continually probe the sand with their rostra in search

of food, readily feeding on younger instars and the disabled of their own kind.

Pentacora leucographa and Saldule coorongensis exist on the same diet. The

above three species together with Saldula brevicornis were successfully kept in

the Jaboratory in air-tight containers, the bottoms of which were covered with

moist blotting paper. The saldids had no hesitation in feeding on dead ferment

flies of Drosophila sp., which were introduced daily, When reared in these con-

tainers, care must be taken to remove the young instars as soon as hatching

occurs, as they feed readily on the eggs which are inserted just below the surface

of the blotting paper,

143

Mating was observed in the laboratory and in the field, and in each case a

definite courtship occurred before-hand. All four mew species described in this

paper behaved in a similar manner. The female remains motionless after the

male gpproaches. They touch antennae, the male becomes agitated and mounts

the female’s back with a sudden spring, and thence moves to her side, copulation

gccurting while the two bugs are side by side. The male’s right or left wing

becomes displaced, and the genital apparatus of both bend towards each other.

The genitalia are perfectly symmetrical, there being no particular preference for

one side, the same pair repeatedly copulating from either side. The female may

walk around during copulation, the male securely retaming his position, but

definitely not by the use of his displaced tarsi or tibiae, although it is possible

that the coxae or femora may have some action in this respect The male must

be rapid in his approach and retreat from the female, as she makes deliberate

attempts to insert her rostrum into his body,

Eggs are normally inserted into the Heshy stems of samphire by Soldula

Psanumobia, Pentacora leucographa, and also presumably by 5. coorengensis,

although no eggs of this species have as yet been obtained im the field; in the

laboratory they prefer samphire to sand. These species, as well as 3. brevicornts,

when kept in the laboratory on moist blotting paper, inserted their eggs. in the

paper around the edges of the containers. The eggs of the three new Saldula species

all have a finely ridged surface, probably due to the impressions caused by the

follicular cells of the ovarioles during maturation. Any accurate comparison of

the eggs is not practicable, all varying within the same limits, the average size

being 0°7 mm. long and 0°25 mm. wide. The eggs are whitish, the anterior being

slightly pointed, the posterior pole somewhat wrinkled. Eggs were obtained

from Saldula psammobia by two methods. The first was in containers with a

layer of sand on the bottom of samphire placed therein. The second was with

damp blotting paper. Those eggs inserted in the plant tissue had their posterior

poles, which were usually wrinkled, protruding, whereas those m the blotting

paper were devoid of such an area. Eggs were also dissected from the oviducts

of S. psamvnebia and these were without any trace of the so-called micropyle

region. This clearly suggests that doubt must be placed on Brindley’s interpreta-

tion (Brindley 1934) of this atea, which she describes in the egg of Salda

littoralis as being ill-defined and occurring on the posterior pole of the egg which

is left protruding from the surface of the mud in which it is laid. A likely

explanation is that the unequal exposure of this posterior pole results in localised

surface stresses being set up which give rise to the wrinkled area.

SALDUI,A BREVICORNIS

This species was reared through all stages in the laboratory using the tech-

niqué already described, The eggs were incubated at 24° C. and 100% humidity,

At two days the eggs became yellowish and eyespots began to show. At three

days eyespots were large and prominent. The first instars emerged at five days

and fed readily. These moulted at three days. The second instar moulted after

another three days. The third, fourth and fifth instars took four days each,

There was definitely no post-natal moult, such as occurs in the Hebridae and

other closely related families.

The first instar is of a light brownish colour with prominent yellow eyes.

The first, second and third antennal seginents are slender and approximately equal

in size, The fourth segment is somewhat Jonger and much expanded, There

is a protinent, light-coloured, Y-shaped line, extending forward from the first

abdominal segment to the head along which splitting occurs during ecdysis. The

pronotum has a transverse groove extending nearly its whole width. This is

144

composed of three definite curves, There is a red-coloured repugnatorial gland

closely underlying the dorsal surface of the abdomen, The legs are approximately

equal, the hind pair being somewhat longer. There is only one tarsal segment.

The second instar is slightly darker, The fourth antennal segment is pro-

portionately not so large as in the first instar, but nevertheless is considerably

larger than the third segment. The mesonotum has a slight transverse depression.

The edges of the thorax and abdomen are slightly explanate. The third abdominal

tergite has a rounded projection posteriorly at its mid-point. This is apparently

connected with the bland mentioned in the first instar. The hind legs are slightly

jonger than the other pairs but only possess one tarsal segment.

The third instar is brownish with a prominent light-coloured sutute, The

fourth antennal segment is larger than the others. The sides of the thorax and

abdomen are definitely explanate. The meso and metanotum have started to

expand posteriorly. The hind tarsi show the differentiation of the first tarsal

segment.

The fourth instar is dark-coloured with a prominent light-coloured suture.

The head shows the three pairs of bristles characteristic of the adult. The third

and fourth antennal segments are equal in length and are somewhat shorter than

the second. The pronotum and mesohotum show further differentiation. The

lateral edges of the pronotum are explanate, the posterior edge is flat and the

callus is well developed, and shows the depressions that form the fovae, The

mesonotum shows further differentiation. The wing-buds are well developed

and the central portion shows characteristic contours, The abdomen has explanate

sides, The third abdominal segment shows the same structure as earlier men-

tioned, The hind legs are much longer than the front, The tarsi of the fore,

mid and hind legs show the differentiation of the first tatsal segment,

The fifth instar is much larger than the fourth, being only a little shorter

than the adult. It is dark-coloured with a definite white pattern, The eyes are

more prominent than in the previous instar. The second antennal segment is

longer than the third and fourth which are equal. The two diverging groaves

which run just in front of the ocelli in the adult are present. There is a dark

polygonal patch between the eyes. The pronotum is similar to that of the fourth

instar. The mesonotum is complexly contoured and has three pairs of definite

white patches on the central portion, The wing buds are further developed. The

metanotum has extended further back, the posterior tips of the meso- and mcta-

notum coinciding, The abdomen has explanate lateral edges, the third abdominal

segment showing the structure earlier described There is a definite colour

pattern, The hind legs are much longer than the other pairs, the first tarsal

segment being the only one differentiated, although the region of the second and

third ts closely shown by the colour pattern,

SALDULA COORONGENSIS

Eggs were obtained from specimens kept in the laboratory and incubated

at 27°C. and 100% humidity. Time of hatching was five days. The instars

resemble very closely those of S. brevicornts,

SALDULA PSAMMOBIA

The instars do not differ significantly from those of S. brevicornis, except

for the fifth which lacks the elaborate pattern of this species, the body surface

being brownish-black or light brown, There is a prominent light-coloured

Y-shaped suture line present,

Tris, Rey, Soe S. Avist, VL Val 74, Plate 1X

2mm

A. Penlaririn lenragreblin ado ile. i, Awtoi, C, Veoreal surface af fennile.

tN, EK Variations i imembrane 1 Antena fh tisha. Gy Pifele instar. Thy) Sadedteder

pomenobia, brachyplerous Jorn. Lo Auda drefofsomd, sil dade, wah moter 0.

Trans, Roy. Soc. S. Aust., 1951 . Vol. 74, Plate X

rere tere

Pres sts

Saldula brevicornis. Adult wale, ewe, and the five instirs.

145

PENTACORA LEUCOGRAPHA

The instars of this species occur in the field with those of S. psammobia.

They are easily distinguished from the latter by the presence of two large white

patches on the fourth abdominal segment, these occurring in all instars.

BIBLIOGRAPHY

BercrorH 1893 Ent, Month. Mag., 29, 279

Brinptey 1934 Proc. Roy. Ent. Soc. Lond., 9, 10; Trans. Roy. Ent. Soc.

Lond., 82, 49

Distant 1904 Faun. Brit. India, Rhynch, 2, 404

Fasrrcius 1903 Syst. Rhync., 113

Hate 1924 Proc. Linn. Soc. N.S.W., 49, 465

Huncerrorp 1918 Journ. New York Ent. Soc., 26, 12

Kirkatpy 1899 Ent., 32, 194; Rev. d’entom., 18, 94

REuTER 1895 Acta. Soc. Sci. Fenn., 21, 5-9

Reuter 1912a Ofv. Finska. Vet. Soc. Forh., 54, A. 7, 71

REUTER 1912b Ofv. Fihska, Vet. Soc. Forh., 54, A. 12, 8

Saunpers 1892 Hemipt. Heteropt. Brit. Is., 173

Van DuzEE 1917 Cat. Hemiptera, America, North of Mexico. Univ. Calif.

Publ. Tech. Bull., Coll. Agr. Agr. Exp. Sta., Ent., 2 (1-x1v), 439

Van DuzEE 1914a San Diego Nat. Hist. Soc., 2, 32

Van Duzer 1914b Canad, Ent., 46, 387

A NOTE ON THE LIFE HISTORY OF THE AUSTRALIAN FRESHWATER

MUSSEL, HYRIDELLA AUSTRALIS LAM

BY I. D. HISCOCK

Summary

The life-history of the Australian freshwater mussel, Hyridella australis Lam. is recorded.

146

A NOTE ON THE LIFE HISTORY OF THE AUSTRALIAN FRESHWATER

MUSSEL, HYRIDELLA AUSTRALIS LAM.

By I. D, Hiscocx*

Communicated by T. Harvey Johnston

[Read 9 November 1950]

SUMMARY

The life-history of the Australian freshwater mussel, Hyridella australis Lam.

is recorded.

The glochidium is hookless and wi’! parasitize Gambusia (lightly); the callop,

Plectroplites ambiguus (heavily); but not the carp, Carassius auratus. The

callop is probably the principal natural host of the glochidium. ‘The larvae attach

themselves to the fins but not to the gills and remain on the fish for twenty-two

to twenty-three days at 20° to 22° C,

From the discovery in 1832 by Carts that the glochidium, for a long time

accepted as a parasite infesting the gills of freshwater mussels, was the larva of

the mussel itself, and from that of Leydig in 1866 that the glochidium, after

liberation from the parent, completed its development as a parasite on fishes, the

life-history of many freshwater mussels has been successfully investigated. The

literature published up to 1910 has been summarised by Lefevre and Curtis

(1912), who investigated 37 species of American freshwater mussels, Of the

life-history of the many Australian mussels little is known, and the atithnr has

found none recorded in the literature.

Routine collections by the Zoology Department of aquatic molluscs from the

lower River Murray and its swamps haye yielded several hundreds of specimens

of Hyridella australis Lam. These are usually placed in glass dishes and

examined for the liberation of cercaria, prior to storing in outdoor aquaria as

stock for research purposes. From time to time, female specimens have been

observed to extrude embryos from early gastrula to free glochidium stages while

under examination in the laboratory. In November 1949 an attempt was made

to study the parasitic stage in fishes. The results of this study are reported

below,

Latter (1891) found that with the mussels Anodonta and Unio, glochidium

larvae were extruded only in the presence of a fish, though he noted abortion of

pre-glochidial stages. Lefevre and Curtis (loc. cit.) have never encountered a

single instance in Anodonta but found the occurrence fairly common in Unio

complanatus and in Quadrula. They concluded that premature extrusion was

probably due to imperfect aeration of the aquarium water,

Abortion has been found to occur in about 1-2% of the collected specimens

of H. australis, The extrusion of embryos, whether abortive or normal spawning,

is similar and has been described elsewhere (Hiscock, 1950). The embryos, in

strings of mucus, adhere to the mussel itself or sink to the bottom of the aquarium.

The presence of whole or chapped-up fish caused no observable reaction in free

giochidium larvae.

*Department of Zoology, University of Adelaide.

Trans. Roy. Soc. S. Aust., 74, (2), Dec, 1951

147

THE GLOCHIDIUM

The embryos femain enclosed in their vitelline membrane until the mature

glochidium stage is reached. Fig. 1 shows 4 late glochidium enclosed in its

membrane, which has no micropyle. The cilia shown at the posterior end were

active and probably serve to circulate water within the membrane. Slow opening

and closing of the shells was observed in a number of the late glochidia. The

rupture of the membrane was accomplished by more active movement of the shells.

O-l mm

Fig. 1-5

1, A late glochidium in its vitelline membrane. 2, Free glochidiam, living, seen

from below. 3, Free glochidium, stained, from above. 4, Glochidium tn the

caudal fin of Gambusia, seven days after infection. §, Glochidium, five days after

liberation from the fin of a callop.

am, adductor muscle; c, cilia; fr, fin-ray; gs, glochidial shell; It, larval thread;

s, shell proper; vm, vitelline membrane.

The free glochidia were hookless and possessed a typical large adductor

muscle and latval thread (once regarded erroneously as a provisional byssus).

The cilia were no longer active and the shells gaped widely apart. Camera lucida

drawings of living and stained glochidia are shown in fig. 2 and 3 respectively.

THE PARASITIC STAGE

Free giochidia were placed in aquaria with three available species of fish,

Gambusia; caliop, Plectraplites ambiguus; and carp, Carassius auratus, Al

three species of fish were observed to take large numbers of latvae into the mouth

and many passed out through the gills. Within half-an-hour some laryae had

148

attached themselves to the fins of Gambusia and the callop, and within two hours

the fins of the callop were heavily parasitised with about one hundred larvae.

No larvae attached themselves to the carp. Hourly inspection of the gills of all

the fish showed that no larvae had attached themselves in this site.

Gambusia were preserved at approximately four-day intervals for more

detailed inspection of the parasitic larvae, By the end of twenty-four hours the

epithelium of the fin had completely overgrown the larvae, which were still casily

visible on the fin margins, Fig. 4 shows a glochidium in the caudal fin of

Gambusia, seve) days after infection. It may be noted that Gambusia is an

aquarium fish in South Australia; the golden carp, an introduced species, ts

abundant in the lower Murray and its swamps, while the callop is a native fish-

TRE POST-PARASITIC STAGE

Between the twenty-second and twenty-third days after infection all the

larvae had become liberated and were collected from the bottom of the aquaria.

‘The water temperature during the parasitic period under observation remained

between 20° and 22°C. About one hundred metamorphosed larvae were

recovered, mainly from the callop, and were similar in appearance to those figured

by Lefevre and Curtis (loc. cit.) for Lampsilis ligamentina. New shell growth

showed beneath the glochidial shell, the mantle was well developed, and locomo-

tion was accomplished by means of a long ciliate foot. The larvae were placed

in shallow dishes on mud taken from the River Murray and daily inspections

were made. Fig. 5 shows an outline drawing of a larva five days after liberation

from a callop, None was found living after seven days.

Records of the finding of glochidia on fish taken from the lower River

Mutray have been kept in the Department of Zoology since 1938. Most of the

larvae have been observed on the callop, bet from the gills, not the fins. Though

this is not in accordance with the findings recorded above, it is possible that these

glochidia were merely entangled in the gill mucus. The following fish have been

observed as hosts of glochidia: callop, Plectroplites ambiguus; Murray cod,

Oligorus mocquariensis; congolli, Pseudaphritis wrvillii; smelt, Relropinna

semoni; silver perch, Therapon bidyana; and catfish, Tandanus tandanus, The

fish wete collected between the months of September and February and in May,

but no collections were made in any year between May and September. As no

freshwater fish have been examined during that period, it cannot be stated with

certainty that no glochidia are present during the winter months. It is probable

that the callop is the principal host of the glochtdium.

ACKNOWLEDGMENTS

The author wishes to express his indebtedness to Professor T, Harvey

Johnston for his interest and advice and for making available his records of fish

examinations since 1938, and to the Commonwealth Research Grant of the Uni-

versity of Adelaide,

- REFERENCES

Hiscock, I, D. 1950 Aust. J. Mar, Freshw. Res., 1, (2), 259-268

Latrer, O. H. 1891 Proc. Zool. Soc., 52-59

Lerevre, G. and Courts; W. C. 1912 Bull. U.S. Bur. Fish., 30, 109-201

GRANITES OF THE PALMER AREA AND ASSOCIATED GRANITIZED

SEDIMENTS

BY J. H. RATTIGAN AND C. F. WEGENER

Summary

The rocks discussed outcrop in the vicinity of the township of Palmer, Hundred of Tungkillo, South

Australia.

149

GRANITES OF THE PALMER AREA AND ASSOCIATED

GRANITIZED SEDIMENTS

By J. H. Ratrican and C, F. WecENER*

[Read 9 November 1950]

CONTENTS

I, Summary - ~ - - + - - “ 149

Il. Intropucrion AND Previous INVESTIGATIONS - - - 149

II. PuysiocraPHy - - - - - 2 “ 151

TV. Genera GroLocy - - - - - = m 151

1, Structure - - - - - & - : 151

2. Country Rock—Sediments and Metasediments - - - 152

3, Granitic Rocks - - - - = = = 152

A. The Palmer Granite - - - i 2 2

(1) Shape of Outcrop - . e - . 2

(2) Nature and Variability - ~ - < 5

(3) Internal Structures and “Xenoliths” - = =

(4) Observations about the Contact - - - =

B. The Rathjen Gneiss - - ~ ca 3 c 157

C. Minor Granitic Outcrops - = - > - 159

4. Migmatitic recks = - - - - = - o 159

5. Pegmatites - - - - - * * 160

V. Ogicin oF THE Granitic Rocks - - - ~ - 161

VI. ConcLusions - - - - « - ul 163

VII, AckNowLEDGMENTS - - - - - = 164

VIII, Rererences - - - - - é - 164

I, SUMMARY

The rocks discussed outcrop in the vicinity of the township of Palmer,

Hundred of Tungkillo, South Australia.

Evidence is strongly in favour of the granites at Palmer having arisen

through granitization of sediments in situ, Further, it is considered that the

processes active at Palmer are connected with those which have wrought

extensive regional metamorphism and metasomatism on the rocks of the

eastern Mt, Lofty Ranges. The Palmer district is but part of this province

of regional metamorphism and granitization.

II, INTRODUCTION AND PREVIOUS INVESTIGATIONS

The area lies 40 miles north-east of Adelaide and comprises some 35

square miles of country south of the main Adelaide-Mannum road in the

vicinity of Palmer. It includes portion of the eastern escarpment of the Mt.

Lofty Ranges together with a small area of the adjacent “ Murray Plains ”

west of the Monarto-Sedan railway.

In this paper most attention is given to the two main granitic outcrops

namely, (1) the Palmer Granite and (2) The Rathjen Gneiss. The former is

the larger and occurs nearer Palmer township, while the latter lies a few hundred

yards to the west of the Palmer granite and is much less conspicuous.

* School of Geology, University of Adelaide.

Trans. Roy. Soc. S. Aust., 74, (2), Dec, 1951

150

PALMER GRANITE

AND

ASSOCIATED GRANITIZED SEDIMENTS

pauen cnamre.....fF ¢] natazen cress. fF 1)

vancose onanre....[F x) samostonesfamenmd [=]

wiken cranmes....E= 3] wevasepments N50)

Quartz. minces______

Fig. 1

General Geological Map.

151

No detailed geological work has previously been undertaken in the

area. Several writers have, however, dealt in some measure with parts pf

it, Hossfeld (1935) dealt with the areas north and west of Palmer and

briefly with the Palmer granite, Jack (1923) examined the Palmer granite

mainly with regard to its utilisation as a building stone and in his report

a chemical analysis of the granite by W. S. Chapman is recorded. A short

report by H. Y. L. Brown (1903) dealt with the Kitticoola Mine mainly

from a mining and economic aspect.

The location of rocks especially referred to in the text is indicated by

specimen numbers shown on the accompanying map of the area (fig, 1),

Ill, PHYSIOGRAPHY

The most prominent physiographic features in the vicinity of Palmer

are the eastern escarpment of the Mt, Lofty Ranges, here known as tlie

“ Palmer Hills,” and the “ Murray Plains” immediately to the east. The

hills rise abruptly out of the plaim along the line of the escarpment fault

which runs in an approximately north-south direction on the western side of

Palmer township.

The Murray Plains comprise gently undulating country stretching

eastwards from the fault line to the River Murray, The plains west of

the Monarto-Sedan railway are mantled with alluvium for the most part

through which project numerous outcrops of older granitic rocks and meta-

sediments, A thin discontintotis capping of ferruginous fluviatile grits of

Tertiary age is occasionally observed at the surface, East of the railway,

inliers of the tonalitic rocks are prominent together with other granitic rocks

and metasediments, Further eastwards, towards the River Murray, fossiliferous

Tertiary marine limestones outcrop extensively,

The Palmer Hills tise abruptly out of the plains and their present

elevation is due to block faulting in the late Cainozeic “ (?) Kosciuskan

Iepoch.” They have been transected by several cast-lowing creeks (Baker,

Harrison, etc.), which have cut steep gorges through the country rock near

the fault line. These creeks join Reedy Creek in the vicinity of the Kitti-

coola Mine, and this creek passes out of the hills onta the plains and flows

in an easterly direction towards the River Murray. The surface nature of

the hills area is very rough and stony. Granite tors of varying size are

numerous in the north-eastern sector while elsewhere the “ bedded” schists

and gneisses project prominently above the ground so that the line of strike

can be traced visually for considerable distances. In the absence of trees

and with a paucity of soil covering, the Palmer [ills are in strong contrast

with those nearer Tungkillo west of this area,

IV. GENERAL GEOLOGY

1, Structure

The couritry rock has been folded into a major unsymmetrical syneline piteh-

ing gently in a south-south-west direction, Minor folding within the major

structure is often highly complicated, especially near the supposed base of the

syncline where tight folding has been intense, The general form of the structure

in section is illustrated in fig, 1,

Much of the eastern escarpment is occupied by a major crush Zone.

This attains a considerable width in the vicinity of the Kitticoola Mine

where it meusures approximately three-quarters of a mile, Forking of the

ancient fault to the south of Kitticoola is probably the cause of the broad

crush zone, The general trend of faulting is in a roughly north-south direc-

852

tion, Although the present elevation of the scarp is attributed to faulting

in the late Cainozoic, the original faulting occurred probably during the

early Palaeozoic era to which much of the fault crushing is attributed. The

original fault must have post-dated the Palmer gramite, as the granitic

rocks involved are shattered and veined, Subsequent mineralization of

the shatter zone caused widespread metasomatic changes within the granite

and was responsible for the introduction of vein quartz, specular haematite,

pyrites, arsenopyrites and carbonate minerals. In the Kitticoola region

especially, gold and ore minerals of copper also achieve considerable import-

ance, The replacement origin of the Kitticoola ates is suggested by the existence of

doubly terminated quartz crystals. Shattering of granitic rocks and metasediments

alike has been considerable and polished shear surfaces with slickensides are com-

mon, Rejuvenation along the older fault lines occurred in the late Cainozoic, This

rejuvenation is evidenced by the bold prominence of the scarp and the steep

gorges cut through it, as contrasted with the low-lying areas to the east.

Further evidence of the wplif¢ is seen tn the differential elevation of the

Tertiary fluviatile grits and conglomerates, which occur both on the plains

and at high levels in the hills. On this basis the relative vertical movement

was apptoximately 700 feet.

2. Counrry Rock — SEDIMENTS AND METASEDIMENTS

Considerable metamorphism and metasomatism has occurred throughout

the region and apart from small areas of felspathic sandstone in the south-

eastern sectors, the original sedimentary rock types are rarely revealed.

The felspathic sandstones occur on both sides of the fault, the more

kaolinised variety occurring on the plains and the more guartzitic variety

in the faulted area. The high ilmenitic content of many of these racks is a mnost

interesting feature from both the stratigraphic and petrologic points of view,

This mineral occurs as numerous thin bands throughout the rock, but in

some cases may attain a width of up io a foot. A comparison of bedding,

as delineated in the sandstones by the ilmenitic bands, with schistosity in

the adjacent rocks, reveals that the schistosity, in close proximity to the

sandstones at least, is sensibly coincident with the original bedding. Meta-

somatised variants of the ilmenitic sandstones, in the form of rutile-bearing

anthophyllite-quartz schists. and also containing parallel bands of ilmenite, are

met with on the plains. Although exposures of both the ilmenitic sandstone and

ilmenitic anthophyllite-quartz schist are scattered, they are abundant enough to

suggest that much of the plains area under consideration here is underlain by this

rock type. A northerly extension has also been recorded by Hossfeld (1935),

Two other occurrences of anthophyllite-quartz schists were exposed in cuttings

along the main Mannum-Adelaide road. One lay immediately west of the Rathjen

Gneiss and the other on the eastern side of the synclinal nose in the north-west

of the area. Both of these displayed very minor amounts of ilmenite,

Other rock types outside the migmatitic zones comprise mainly quartz-

felspar-mica schists, granulitic quartz-felspar rocks and thin beds of dark

amphibolitic rocks.

3. Granitic Rocks

A. Patmer GRANITE

The Palmer granite comprises the major portion of the granite area,

covering a little more than two sqtare miles of country immediately west

of Palmer township. The main Mannum-Adelaide road cuts across it at its

greatest width, but the Granite does not extend far north of this road.

This granite has a distinctive spheroidal mode of weathering which has

given rise to tor-strewn hills, so much a feature of the landscape on both

153

sides of the main road (pl xi, fig. 1). The tors range up to thirty

feet or more in diameter and their mode of formation is well illustrated in

the concentric cracks cbservable on the face of a road metal quarry some one

and a half miles west of Palmer,

(1) Shape of Outcrop

The outcrop js lenticular and elongate, trending in a general north-south

direction, It is appronisfately three and a half miles long and one mile at

its maximum width, near the northern end, and tapering somewhat to the

south,

Although a certain amount of discordance appears to be present, acttial

contacts are almost completely lacking due to surface soil cover and hence

close study of these was not possible, The granite body, however, shows

general concordance with the metasediments and its margins are for the

most part roughly parallel with the near north-south strike of the metasedi-

ments. On the north side of the main road the margin for several hundred

yards does bear discordant relations with the strike of the metasediments,

(2) Nature and Variability

_ ‘Traverses’ across the granite from east to west reveal two notable features.

First, the granite is extremely variable as regards appearance, grain size and

other textural characters, relative proportions of component minerals, mode of

weathering and jointing, and itt the degree in which foliation has been developed.

Secondly, the more prominent varieties trend in conformity with the margins of

the outcrops, that is, generally parallel with the strike of the adjoining meta-

sediments,

The most prominent variety is the coarse pink microcline granite in which

the tor structure is best developed. This is one of the few varieties considered to

resemble magmatic granite. It has a tendency to be porphyritic with microcline

crystals often attaining a length of two centimetres. In thin section the texture

of a typical Palmer Granite (8168) may be said to resemble the crystalloblastic

type more than the pyrogenctic. Quartz is abundant as crystals of variable size

and irregular outlines, Microcline displays the typical “crosshatched” structure,

and peculiar skeletal intergrowths of quartz may he seen in certain crystals.

Plagioclase is not notably inferior in abttndance to the alkali felspar. It occurs

as slightly clouded colourless crystals of low positive relief. Alteration is often

most intense within a central kernel, the outer portions of the crystals being clear.

The maximum extinction angle in a plane perpendicular to 010 is 5°, which corre-

sponds with an oligoclase of composition near Ab,,An,). Myrmekitic intergrowths

of quattz in plagioclase are occasionally seen. Buiatite is not abundant but is an

intensely pleochroic vaticty; X == yellow, Y = Z= deep brown (almost opaque).

Ilmenite and sphene are notable accessories occurring in association with one

another. The sphene is leucoxenic in nature and is apparently derived from the

associated ilmenite. Apatite is also abundant in accessory amounts,

A chemical analysis of this rock (8168) was made by J. H. Rattigan and this,

together with the norm, ate tabulated herewith.

154

sid; - - - - 74°62 NORM;

AlxO: - - - - 13-91

FeO: - - - - 1°18 Quartz 38-40

FeQ - - - + +92 Orthoclase 21-3

MnO - - - - = Plagioclase Ab 26°72

MgO- - - - °55 An 51 423

CaQ - - - - 1-61 Corundum 2.04

NaO - -= ~ = 315 Hypersthene Fs “26

KO - - = + 3:56 En 14o (1°66

H20+ > se & +25 Mapnetite 1462

HiO—- - - - 14 Iimenite 61

Ti0e - - - - 32 Apatite +20

POs - - - - “08

S35 & ott 99-89

100-36

Among the numerous other varieties of granitic rocks in the Palmer Granite

are a porphyritic microgranite, a compact greasy grey quartzose type, a pink

aplitic granite and a pink granite gneiss containing a considerable amount of

hornblende. A coarsely gneissose ted granite is promitient near the Kitticoola

Mine. This is also subject to some variations in mineral composition, but this

is attributed to later pneumatolytic processes.

In a report on the quality of the granite as a building stone, R. L. Jack (1923)

also mentioned the variability in nature of this rock. He found it difficult to

reconcile the strongly sheeted nature of the aplitic variety.as observed in the

toad-metal quarries, with the adjacent tor structure in the coarser granite. He

could not envisage both types as arising from a single magma and subjected to

the same conditions in later time. In explanation Jack proposed a “dyking’’ hypo-

thesis whereby a younger granite was stipposed to have dyked an earlier one.

The present wider and more intensiye field studies suggest that this theory cannot

be supported,

Metasomatic Variant of the Palmer Granite—Along the eastern ridge of the

escarpment an abnormal phase of talcose granite extends from just west of

Palmer township southwards fo.Kitticoola and Reedy Creek. Occurrences of this

granite may be readily distinguished by its angular, jagged and blocky mode of

weathering which contrasts strongly with the tor structure of the adjacent normal

granite. The abnormal granite has been shattered and fractured as a result of

faulting, presumably during an early Palaeozoic epoch. The infilling of the

fissures by secondary quartz, haematite, pyrite and rarely chalcedonic silica and

calcite is characteristic. Polished shear surfaces and slickensides are a feature

and are often outlined in quartz or haematite. The blocky mode of weathering

is a consequence of the shattering and secondary veining.

From a study of this granite on the Kitticoola ridge and its relations with

the coarsely gneissic red granite type, which outcrops immediately to the west,

it Is apparent that the abnormal granite is a meiasomatic variant of the normal

granite. All gradations from the coarsely gneissic red granite to a pink and green

talcose granite may be observed along the banks of Reedy Creek in the vicinity

of the Kitticoola Mine. The biotite and plagioclase can be seen in all stages of

alteration, The red microcline is relatively unaffected. The textures of normal

and abnormal types are identical except where veining with secondary silica has

interfered.

155

Field study leaves little doubt as to the origin of the talcose granite, namely,

through replacement effected in the tiormal granite in the crush zone, Petro-

graphic evidence supports this, Pegmatites within the granite haye also suffered

similar alteration to talcose types.

(3) Internal Structures and “Xenoliths”

The gneissic structure of the Palmer granite is recognised mainly by the

paralle) orientation of biotite, and also hornblende in varieties on the western side

of the outcrop. In one group of granitic rocks, namely the grey microgranites,

this parallel structure would be more appropriately termed schistosity, In some

ooarser granites, however, such as the red Kitticoola granite, segregation of biotite

flakes has resulted in a pronounced foliation structure being developed, The

strike of gneissosity is in general parallel with the strike of schistasity in the

adjoining metasediments except where local distortion occurs, possibly due to

original minor folding in the transformed sediments.

Dark schistose “xenoliths”™) are numerous within the granite, varying in

size from an inch to several feet in diameter. They are-seldom found lacking in

any portion of the granite, even in the central portion, where they are mo Jess

abundant than near the contact. In nature they are fine-grained and usually

biotite-rich, which gives them a marked schistosity. Their form is usually ovoidal,

or elongated and ellipsoidal with smooth edges, and they are not the jagged,

irregular assortment so often a feature in an injected magma whose upward

movement has been assisted by stoping. The longer axis and also the schistosity

of these “xenoliths” are almost itivariably orientated parallel with the direction

of foliation in the granite. The more basic types of “xenoliths” are thought to

be basified remnants of country rock still remaining after transformation of the

remainder of the sediments, Lighter types are common although mot so con-

spicuous as the darker varieties. They are usually fine-grained in nature and

often schistose, but grade into “ghost remnants” almost identical in mineral com-

position with the granites. These “ghost structures” are less regular in shape

than the more conspicuous basic xenoliths”, They also preserve the same general

orientation and conformity with the foliation and often weather more readily

than the enclosing normal granite.

(4) Observations about the Contact

The margins of the Palmer Granite are for the most part roughly parallel

with the strike of the adjacent country rock. The area previously mentioned

on the north side of the main road is the most prominent exception and here there

are discordant relations with the strike of the surrounding rocks for several hun-

dred yards of the contact. Exposures in the immediate vicinity of the contact in

general are almost universally absent or very poor, due to a mantle of alluvium,

One smail exposure in a creek bed of an actual contact consists of a. fine-medium-

grained granite forming a fairly sharp contact against a bard grey even-grained

granuliie showing no visible schistosity. Microscopically the grenulite (8157)

has a granoblastic texture. Quartz and microcline, equally abundant, are the two

main mineral constituents, plagioclase being present in accessory amounts only.

Both muscovite and biotite are fairly abundant. Other accessories, all of which

are prominent, are epidote, sphenc, zircon, calcite, iron oxides and tourmaline,

The discordatice mentioned above allowed for the collection of a series of

rock specimens (8160A to 8160F) along the strike of a schist which led into the

() The term “xenolith”, ac here used, is not in strict accordance with its common

usage, bit for convenience it has been used to indicate the residuals of country rocte

which bave not been completely melasomatised,

156

granite. The specimens were taken at intervals over a distance of about two

hundred yards. A microscopic study of thin sections of these rocks reveals the

gradual mineralogic and textural changes in the transition from schist to granite.

The parent rock (8160A) of the series is a fine-grained grey guwarte-felspar-

biotite-schist with quartz and biotite in obvious abundance. Segregation of the

biotite is not particularly noticeable in the hand specimen. Microscopically it has

a granoblastic texture, somewhat modified by the more or less parallel alignment

of thé biotite. Grain size is of a fine and uniform nature. Qwartz is very

abundant and fairly clear. Biotite is also abundant and shows definite directional

structure. The plagioclase is an oligoclase of composition near Ab, )An.,, buat

rarely shows twinning. Only a small amount of microcline is present, and musco-

vite, apatite, zircon, tourmaline and ilmenite occur in accessory amounts,

Specimen 8160B is somewhat darker and more compact macroscopically, with

alternating lighter and darker bands. In thin section the layers of muscovite are

numerous and closely spaced. Crystals of this mineral are now larger and more

idioblastic, Biotite occurring in the muscovite layers shows slight alteration to

chlorite. Tourmaline crystals are now much larger and unusually abundant,

Specimen 8160C is somewhat lighter and slightly coarser in appearance than

8160B. Microscopically, directional structure is less marked and grain size is

more variable, Plagioclase is more abundant but still commonly untwinned. Ie

is an oligoclase of composition near Ab,,An,,. Muscovite is less abundant but

biotite is on the increase, ‘Tourmaline is much less abundant and only occasional

crystals occur.

‘Specimen 8160D is a bimica-quarte-plagioclase migmatite. Macroscopically

it is a coarser looking rock which has suffered slight local folding and is richly

biotitic, The strongly biotitic bands alternate roughly with quartzo-felspathic

bands. Several small crystals of apatite were seen embedded in biotite-rich bands.

In thin section both biotite and mtiscovite show segregation along somewhat

contorted lines. Potash felspar is still absent but quartz and oligoclase are

abundant. Apatite is a prominent accessory and zircon is still conimon both as

detrital-like grains and as inclusions in biotite, Iron oxides occur in slightly

increased amounts and commonly occur as irregular intergrowths in the musco-

vite laths, ,

Specimen 8160E is a somewhat weathered pink granitic gneiss. The direc-

tional structure that the biotite assumes shows evidence of residual minor rock

flexures, Biotite is now much less prominent. Microscopically this rock exhibits

a typical crystalloblastic texture and consists essentially of quartz and felspar

with smaller amounts of biotite and other accessories, The edges of the quartz

are considerably sutured and inclusions of microcline, biotite and small crystals

of tourmaline are common in this mineral, Microcline is abundant as slightly

turbid xenoblasts, but plagioclase is less prominent. It is still an oligoclase of

composition about Ab,,An,,. Biotite is present in small quantity only and

muscovite is almost absent. Several large xenoblasts of ilmenite are present and

shew slight alteration to lencoxene. Other accessories are zircon, apatite, tourma-

line and orthite.

The final specimen (8160F) in the series is a fine-grained pink granite,

slightly weathered, with an even distribution of biotite. In thin section it is

essenbally similar to 8160E but slightly finer-grained. Leucoxene occurs as an

alteration product of ilmenite.

Modal proportions of the mincral constituents of each specimen with added

discussion are given later.

157

Several hundred yards further east along the contact is another interesting

example of a similar nature. Here several narrow bands of felspathised sandstone

occur just inside an area of compact medium-grained “leuro-granite’. These

several hands may be traced outwards along the strike into a fairly wide series

of felspathised sandstones beyond the contact.

B. THe RaTHJEN GNEISS

The Rathjen Gneiss lies on the western side of the Palmer Granite outcrop.

it has its greatest development north of the main road, but to the south it con-

tinues for several miles as a narrow belt some 200 feet in thickness, striking in

a near north-south direction, It is finally faulted out by the Cainozoic fault.

Only that portion on the south side of the road and for about 200 yards on the

north side is considered here.

Although the dip and line of strike of the strata remain relatively undis-

turbed south of the road, considerable variations due to folding occur on the

notth side. Visible contacts are more numerous and better exposed than is the

case with the Palmer Granite, and this allowed for a closer study of these, The

outstanding feature is the concordant nature that this granite bears with the

adjacent country rock even where close folding exists. Nor is this folding con-

fined to the country rock, for these structures are reflected well within the granite.

This is clearly illustrated in the map (Fig. 2) of portion of a contact at the

northern end, drawn on a scale of 25 feet to an inch, The southern half of this

sector, due to better exposures, gave the more definite evidence, and although the

northern part is less definite, general field relations indicate the structure as shown,

The. Gneiss is somewhat vatiable in nature (pl, xi, fig. 3, 4) but is typically

strongly foliated and coarse-grained, The foliation, which is due to the segrega-

tion of laminae of biotite, is everywhere parallel with the strike of the adjoining

rocks. The tor structure is here much modified by the influence of pronounced

foliation and the outcropping rocks have rounded tops with flattened walls dipping

at an angle to the ground surface in conformity with the surrounding metasedi-

ments (pl. xi, fig. 2). “Xenolithic” remnants, although not numerous, preserve

their regional orientation. An example of one variety measured four feet in

length by a maximum width of two inches,

A typical specimen of the Rathjen Gneiss (8308) was examined microscopi-

cally. It displays a coarse-grained crystalloblastic texture with marked

gneissosity. Quartz and felspar are by far the most abundant constituents with

biotite in lesser quantity, Sphene and ilmenite are unusually abundant as

accessorics and the former is oflen distinguishable in the hand specimen, Quartz

shows much variability in size, and suturing of the edges is common. It also

occasionally occurs as myrmekitic intergrowths and quite commonly as rounded

iteliusions, in felspar. The felspar is fairly fresh and some sutured edges are also

evident here. Plagioclase and microcline are almost equally prominent. Twinned

sections of plagioclase normal to 010, give a maximum extinction of &° and with

an R.IL. > halsam, indicate it as an oligoclase of composition Ab,,An.,. The

microcline is readily distinguished by its excellent “crosshatched” structure.

‘Biotite is strongly pleochroic from nearly black to light brown and is segregated

along definite parallel directions. ITlmenite occurs as large black idioblasts com-

monly showing slight alteration to leucoxene. Brown, slightly pleochroic idioblasts

of sphene are mainly concentrated in the biotite-rich bands and are unusually

abundant. Partial alteration to leucoxene is common, Apatite is also concen-

trated in the biotite bands, but not as abundantly as sphenme. Zircon is present in

stall accessory amounts only, mainly as inclusions in biotite.

ENLARGED PLAN

RATHIEN GNEISS CONTACT

158

LEGEND

Rathjen Gneiss

Schist & Grelss

Pegmatifes

Quarts Reefs

Amphibolite

Schistosity

fottation

Pitch of Folds

Contact. observed

Contact_ inferred

Fig. 2

159

Results of a chemical analysis of the Rathjen Gueiss (8308) by C. F.

Wegener, together with its norm are given below.

SiO; - - - - 73-05 Norm:—

ALO, - - - = 12-81

FeOQz- - - ~ 1-54 Quartz 3588

FeQ - - - + 230 Orthoclase 18-90

MgO - - - —- — +64 Plagioclase — Ab 28°82

Gi. 5 2 = Engh An 8-06 36-88

NaQO - - - = 43-42 Corundum “71

KO - - + - 3-15 Zircon “18

HO+- - - - +49 Hypersthene Fs 1:45

HO—- - - + <6 En 1-60 3-05

TiO, - - - - +48 Magnetite 2-32

P30. - - - - -10 Ilmenite 1-52

/MnO;- - - - Tr Apatite 34

ZO - - = = +9 Pyrites *12

ys Se eS

—— 99-90

100°32

C. Mrnor Granitic Outcrors

Outcrops of granitic rock oecur sporadically among the country rock, both

of the hills and the plains. They are invariably of medium and even grain but

vary in colour from pink to white. Many are apparently granodioritic in nature

with a notable biotite content, while others are aplitic and non-biotitic. Lineation

in many of these masses is absent.

One of these granitic masses is a narrow curving band outcropping around

the nose of the pitching syncline in the north-west portion of the area and again

illustrates the concordance of the granitic tock with the structure of the country

rock, It is a handsome white rock, granodioritic in nature, commonly streaky in

appearance and containing clots and lenticles of biotite. On either side of the

outcrop are saccharoidal quartz-plagioclase-hiotite-schists with biotite mainly sepre-

gated into layers.

4 QOrHer MicMartitic Rocks

The granitic rocks ate migmatitic in nature but the migmatites with a less

obvious granitic texture have yet to be described, These rocks include veined

gneisses, compact “permeation” migmatites, contorted composite gneisses, biotite

enriched schists and foliated amphibole-epidote gneisses.

The term weined gneiss has been applied to those rocks with a characteristic

alternation of parallel quartzo-felspathic and schistose layers in preference to

injection gneiss or “lit-par-lit” gneiss, which more usually presuppose injection of

magmatic materials (pl. xii, fig. 1 and 2). These rocks are prominent,

adjoining the Rathjen Gneiss on its western side and to a lesser degree about the

Palmer Granite (mainly on the east and north-east side) and about the minor

granitic outcrops, The veins of quartzo-felspathic (granitic) material vary in

thickness but may range tip to more than an inch, They are commonly bordered

with thin layers. of biotite,

' The writers fail to see how actual injection could produce the remarkable

parallelism so commonly seen in the adjacent granitic and schistose layers without

distortion of the foliation, They consider that layers of schist have been locally

transformed through permeation and granitization along the direction of schis-

tosity to produce the characteristically veined structure.

160

Veined gneisses grade into the Rathjen Gneiss as the schistose layers hecome

more granitic in texture. The strongly foliated Rathjen Gneiss is considered to

represent a more intense stage of granitization than that which produced the

yeined rocks, The gneiss is considered to have arisen by the intimate replacement

of schist along the planes of schistosity with the segregation of biotite into lenticles

and layers parallel to these planes. The biotite folia which impart the foliation

are cotsidered as relicts of schistose layers equivalent to those in the yeined

gneisses.

Tn certain areas, such as along the cliffs in the lower reaches of Harrison

and Baker Creeks and on the plains in the south-eastern part of the area, con

torted composite gneisses are exposed. The contortions are clearly outlined by

ptygmatic quartzo-felspathic veins,

The granulitic rocks adjacent to the Palmer Granite never develop a veined

structure, since their close-textured recrystallized aggregate prohibits the entrance

of replacing emanations along preferred directions. Coarsely foliated amphibote-

quartz and amphibole-epidote-quartz rocks occur adjacent to the granite.

Close-textured even-grained crystalline rocks with no prominent parallel

structure are met with between the Palmer and Rathjen bodies. These may be

referred to by Read’s (1948) term “permeation’ migmatite,

The mica schists surrounding the Rathjen Gneiss on the west are sometimes

marked by considerable enrichment in biotite which is segregated within the

schists in planes parallel to the schistosity. The biotite may be as thin laminae

or as broad sheets six feet or more in thickness, Biotite enriched schists are

also observed about some of the minor granitic bodies. Outwards from the zone

of granitization in each case, the segregated layers and sheets of biotite are absent

from the schists. This biotite enrichment may result from the expulsion of

excess Fe and Mg ions from the granitized zone into the surrounding meta-

sediments,

5 PrGcMAtrTEes

Thee range from simple quartz and quattz-microcline types, including

graphic varieties, to the. more complex ones carrying rare minerals. They vary

in size from a fraction of an inch to several yards in width and the larger ones

have been traced for a distance of more than a mile, Grainsize is usually coarse

in the complex types to fine in the aplitic varieties. Grainsize may also vary

within the one vein from a coarse, highly siliceous central portion, to a fine-

grained margin of granitic character. Colour of the microcline is usually pink,

occasionally brick red and sometimes milk white. Albite is prominent im some

pegmatites. The smaller pegmatites are concordant, while the larger are more

commonly discordant,

The more complex pegmatites are confined mainly to the north-west sector

in the Harrison Creek area and the great majority run roughly parallel in an

east-west direction. Several of these pegmatites about a mile south of the main

road contain notable beryl in association with muscovite, red garnet, tourmaline

and chlor-apatite. The felspars include albite in addition to microcline.

crystals were found up to six inches im length and tourmaline up to one foot in

length, The muscovite is a pale green variety occurring in small books only,

The red garnets show well developed rhombic dodecahedral forms.

Grarts Ridges — The south-west corner of the area features several high

ridges and reefs of milky quartz. These ridges rise sharply fifty to a hundred feet

above the surrounding country and show up prominently as resistant level-topped

masses capped in part by horizontal Tertiary grits and gravels. They have been

traced for a mile or so in length and usually end abruptly.

161

_V. ORIGIN OF THE GRANITIC ROCKS

Certain features which characterise the granitic rocks in the Palmer area

are set out below,

(1) The granitic rocks are more of the nature of gneisses than magmatic

granites.

(2) The granitic rocks are extremely yatiable in nature,

(3) The outcrops show a general concordant relation with adjacent meta-

sediments.

(4) Foliation and orientation of “xenoliths” within the granitic bodies are also

concordant.

(5) Minor structures are preserved as relicts within the granites. Structures

in the metasediments near the contact are reflected well into the granitic

bodies.

(6) Desilication phenomena, including basification, characterise the frontal zone

around the granitic outcrops.

(7) The textures of the granitic rocks in section resemble the crystalloblastic

type more than the pyrogenetic,

(8) The contacts of the granitic rocks with the metasediments are often grada-

tional,

Tt is considered that these facts point to granitization in place ag the process

whereby the granitic rocks originated, The source rocks which have been selec-

tively transformed to granitic rocks ate believed to be sediments ranging from

felspathic sandstones to greywacke, the variation in the source sediments being

reflected in the type of granitic rocks now found. The purely quartzo-fe!spathic

“leucogranite” found in the Palmer body is considered to originate from an

atkosic rock, whereas the richly biotitic Rathjen Gneiss is thought to have a more

impure greywacke as its source.

Because of the highly quattzose nature of some varieties of Palmer granite

and the apparent trend of the ilmenitic sandstone, south of Kitticoola Mine, into

the granite, consideration was given to the possibility of the granite, at least in

part, being a transformation of this samdstone. As expastires were ofice again

poor around the contact, no direct evidence could be obtained, but a granitic rock

collected a short distance north of the sandstone series revealed the presence of

some ilmenite in the hand specimen. A magnetic analysis of some basified

“xenoliths” revealed a notable proportion of ilmenite. One case yielded 2% by

weight. A microscopic analysis of many granites has also shown an unusual

abundance of sphene which is invariably associated with, and apparently derived

from ilmenite, since ilmenite often comprises the nucleus of the sphene crystal.

Thus with the sphene content included, the amount of litania involved would

have been considerable. Large sphene crystals up to half an inch in length,

observed in some of the amphibolitic rocks of the migmatite zone, may represent

a culmination in TiO, through expulsion of that constituent during transforma-

tion of the sediments. Rutile, present in some rocks, as revealed under the micro-

scope, may also be derived at the expense of the titania content of ilmenite. A

quartz reef, just east of Palmer, contained rutile crystals more than two inches

tong.

It is apparent, therefore, that one should not disregard the theory that the

imenitic saridstones may be the source rocks of the Palmer Granite. Furthermore,

since some of these ilmenitic sandstones are similar in appearance to the ilmenitic

sandstones nearer Adelaide and recognised as belonging to the base of the Adelaide

System, and considering the relatively few occurrences in the remainder of the

Mount Lofty Ranges, it is suggested that they might belong to this late pre-

Cambrian tock system,

162

Mineralogical changes occurring between the parent country rock and the

granite in the series 8160A-8160F described earlier are illustrated in the variation

diagram (Fig. 3) drawn up from modal proportions of mineral constituents. in

the separate rocks shown herewith.

Constituents S8160A 8160B 8160C 8160D 8160E 8160F

Quartz - «+ 58-7 53:6 §3°3 42°7 43-0 4454

Plagioclase - 10°8 100 15:7 23:0 16:0 18°5

Microcline «- 6:3 = —_— _— 35:0 326

Biotite - - 22-7 22:6 2340 27-5 5-0 4-0

Muscovite - "3 12-1 7-0 5-0 | 2

Accessories - 1:0 2-1 1:0 2:0 1-0 1-4

PERCENTAGE

DGistoceens

BIB0A. 81608 BI60C 8i60D BIGOE BI6oF

ROCK NUMBER

Fig. 3

Variation diagram to show change in mineral composition in transformation

of schist to granite,

It can be seen from the variation diagram that desilication of the rocks at

the contact is a notable feature. The most striking change is a basification process,

and a geo-chemical culmination in the cafemic constituents, and also in boron

and phosphorus is indicated by the increase in the modal amounts of biotite,

plagioclase, tourmaline and apatite. Boron reaches its culmination in specimen

8160B and a boron “front” has apparently proceeded in advance of iron and

magnesium. The granitic end of the series shows a decided increase in potash

with a corresponding decrease in the femic constituents as compared with the

parent rock (8160A), shown by the increase and decrease respectively in modal

proportions of microcline and biotite.

The granitic rocks at Palmer, therefore, appear to have arisen by a process

of ultrametasomatism through the introduction of certain constitucnts and the

removal of others. There has apparently been a considerable influx of potash

with concomitant expulsion of cafemic constituents, titania, phosphorus, etc.,

into the frontal zone. The activity of volatile constituents during transformation

is indicated by their presence in the constitution of distinctive minerals in the

frontal zone, such as boron in tourmaline, sulphur in pyrites, fluorine in

143

fluorapatite, chlorine and phosphorus in chlorapatite. Emigration of some silica

may be indicated by the pseudo-eutectic structures of quartz in alkali felspar,

since, according to Backlund (1946), “'The emigration of silica is indicated by

the wonderful implications of quartz and potash felspar, These have the appear-

ance of eutectic structures but the propertion of quartz to felspar varies steadily.”

The source rocks of the Rathjen Gneiss were probably more basic in nature

than those responsible for the Palmer Granite and the transformation to gneiss

was accompanied by the emigration of considerable iron, magnesium and titanium

fixed in the frontal zones as biotite and iron oxides, amphibole, and sphene respec-

tively. Numerous small crystals of iron oxide several millimetres in diameter

are often concentrated in the veined gneisses adjacent to the Rathjen Gneiss.

Tn conformity with the granitization hypothesis, the variability of the granites

is considered to be due to variability in nature and composition of the source

sediments and the extent of granitization suffered by them. The leuco-granites

and aplitic varieties are no doubt due to the indifferent susceptibility to granitiza-

tion shown by the purer psammitic rocks in general. The idea that injection of

magma should have produced such a variety of rock types seems hard to accept.

The dark ellipsoidal “xenoliths” are regarded as basified remnants of the

original rocks which have escaped the general transformation to granite. They

ate notably richer in biotite, ilmenite and sphene than their enclosing granite.

With respect to the gtieissic structure ol lhe granitic rocks, it has been shown

earlier that the foliation of the Rathjen Gneiss is consulered to be a residual

primary structure, the biotite folia representing the extreme case of the basified

layers of the veined gneisses. In the Palmer Granite, the parallel structure is also

considered a consequence of primary structures, This is supported by the essential

parallelism of foliation with schistosity in both the country rock and “xenoliths”.

The contorted structures in the granite most probably represent relicts of original

structures such as minor folding in the transformed rocks. Certain conclusions

made by Sedetholm (1923) regarding gneissic granites of Finland are relevant in

this respect. He dismisses any dyramo-thermal action as directly responsible for

some gneissic structures. He states, “where they are striped, the phenomenon is

ustially caused by the more or Itss completely resorbed inclusions. of foreign rocks

whose femic constituents remain gas stripes of mica,” and further, “when they

are pntissose, this is mainly due to the fact that they have absorbed older schistose

tock, The parallel texture is probably due to the assimilation of this schistose

rock.” Variability in the degree to which gneissose structure is developed depends

on the proportion of Initial femic constituents. In many of the granitic rocks

at Palmer this was apparently low, some of the racks showing negligible quantities

of biotite.

VI. CONCLUSIONS

A study of the Palmer area strongly suggests that the granitic rocks have

resulted irom granitization of sediments. in place. The area dealt with is but

a small part of a much larger region along the caster sector of the Mount Lofty

Ranges and the adjacent Jowlands in which similar rock types are exposed. It

wold appear that various features which characterise this region, namely, the

folding, the regional metamorphism, the widespread pegmatization and sporadic

granitization, and magmatic intrusion (as at Murray Bridge, 15 miles to the

south) were all attendant upon the subsidence of Precambrian geosyneclinal sedi-

ments into a high temperature region of the crust. Stresses provoked by crustal

expansion initiated folding movements. Regional metamorphism occurred on a

grand scale, and in favourable locations gratitization was accomplished. The

origin of the transforming Auids and those responsible for the widespread pegma-

164

tization possibly lies'in the fusion at depth of easily melting portions of the sedi-

mentary mass, and the squeezing out of such by orogenic presstire to areas where

they became active. Similarly generation of magma by fusion at depth and later

intrusion to higher levels may have given rise to the fiuorite-bearing batholyth

exposed at Murray Bridge and elsewhere,

At the present time very little detailed mapping has been done amongst these

rocks of the eastern Mount Lofty Ranges and their stratigraphic position and

relationships are unknown. The possibility exists that they represent regionally

metamorphosed and granitized sediments of the Adelaide System but further

mapping must be done before any definite conclusions can be drawn. The recog~

nition of rutile-bearing quartz-anthophyllite schists as magnesian metasomatised

equivalents of ilmenitic sandstones should also be considered in such future

mapping.

Vil. ACKNOWLEDGMENTS

The authors are indebted to Professor Sir Douglas Mawson, of the

Department of Geology, for suggestions and facilities for the work. Our thanks

are also due to Mr, S, B. Dickinson, Director of Mines, for facilities made avail-

able in the final stages of the work, and to Mr, R, C, Sprigg, Senior Geologist

of the South Australian Geological Survey, for much helpful advice in the

preparation of the report for publication, This investigation was in part assisted

by a Federal Research Grant,

VIII. REFERENCES

Hacxiunp, H. G. 1946 The Granitization Problem, Geol, Mag., 83, No. 3

Brown, H. Y¥, L. 1903 Kitticoola Mine, Hundred of Tungkillo, S, Aust.

Report of Govt. Geologist of S. Aust. Geological Survey

Hossretp, P.S. 1935 The Geology of Parts of the North Mount Lofty Ranges.

Trans. Roy. Soc. S. Aust., 59

jack, R. L. 1923 The Building Stones of South Australia, Geological Survey

of S, Aust., Bull. 10

Reap, 1H. H. Meditations on Granite, Pts. 1 and 2:

1943. Proc, Geol. Assoc., 54, Pt. 1

1944 Proc. Geol. Assoc., 55, Pt. 2

Reap, H. H. 1947 Granites and Granites. Geol. Soc. of America, Memoir 28

Reynotns, D. L. 1946 The Sequence of Geochemical Changes leading to

Granitization, Quart. Jour. Geol. Soc. of London, 102, Pt. 3

Reynotps, D. L. 1947 The Granitic Controversy. Geol. Mag, 84, No. 4

SEvERHOLM, J. J. Om Granit och Gneiss, Bull. de la Commission Geologique

de Finlande, No. 23, pp. 96-110

SenexuoLM, J. J. 1923 On Migmatites. Bull de la Commission Geologique

de Finlande, No. 58, pp. 75-150

Vol. 74, (2), Plate XI

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THE BASIC IGNEOUS ROCKS OF THE BLINMAN DOME

BY PETER F, HOWARD

Summary

The Blinman dome is comprised of middle and upper Adelaide System sediments which were

faulted and crushed and subsequently intruded by basic igneous magma during post-Cambrian

times. This diastrophism is discussed and petrological descriptions of the basic and related rocks

submitted. Attention is drawn to the arrangements of the basic bodies and an early form of ring

dykeing is suggested for the unique structure.

165

THE BASIC IGNEOUS ROCKS OF THE BLINMAN DOME

By Peter F. Howarp

[Read 9 November 1950] ~

SUMMARY

The Blinman dome is comprised of middle and upper Adelaide System

sediments which were faulted and crushed and subsequently intruded by basic

igneous magma during post-Cambrian times, This diastrophism is discussed and

petrological descriptions of the basic and related rocks submitted. Attention is

drawn to the arrangements of the basic bodies and an early form of ring dykeing

is suggested for the unique structure.

CONTENTS

Page

1. Inmaopucton = - = 6S

2, Notrs To ACCOMPANYING MAPS = - = = = - = = = 168

3. SrraticraPHy - - = - = = = += = = = = 166

4. DrasTROPHISM AND ACCOMPANYING INTRUSIONS - - - - - 169

5. EFFECTS OF RESIDUAL STRESS ON INTRUSIONS - - = - - - 171i

6. FIELD RELATIONS OF BASIC ROCKS - - = - = - - - 172

7, MINERALOGY +) @ + & & & &= ~~ =~ = = Sh

8 Prerrowcy - - - - = = 5 = = += = = = 197

9. PErROGRAPRY os le See te Os feet a

10. REFERENCES f. So ede Sos tS ee ada Dy db te F188

INTRODUCTION

In the vicinity of Blinman occur a great number of small-scale igneous

intrusions into the middle Adelaide System, which consist of (1) an older

group of basic intrusions giving rise to intraformational flows, and (2) a

later period of igneous intrusions m the form of transgressive dolerite bodies.

These occurrences and the rocks considered herein occur within a radius

of four miles of the centre of the Blinman dome. Other intrusions occur

six miles to the N.N.W. at Wepowie, fourteen miles east on the road to

Wittrealpa and twelve miles to the south at Enorama, which is at the head

of the Oraparinna dome. In all cases the intrusions are in a belt of crushed

sediments.

The horizons of the lower beds of the Blinman dome have been deter-

mined in relation to a known marker horizon in the system at Mt. Emily,

and fall into the upper section of the slates and arcnaceous series overlying

the main tillite horizon. Masses of intraformational melaphyre occur within

this slaty horizon, and later irregular shaped stocks intrude the system to

points above this horizon.

Though the region was an important copper field from 1862 until 1918,

references to previous work on the central area and igneous rocks are limited

to Dickinson (1942) and Howchin (1922), with subsequent petrological

notes by Benson (1909). Mawson has made a special study of the sedimen-

tary rocks of the surrounding region; see especially Mawson (1942).

NOTES ON THE ACCOMPANYING MAPS

Advantage was taken of aerial photographs kindly made available by

the Department of Defence. A photo-geological map of the Parachilna-

Trans. Roy. Soc. S. Atist., 74, (2), Dee, 1951

166

Blinman-Wirrealpa district was drawn up from a trimetrogon set consisting

of two vertical runs coupled by an oblique set covering the central portion

including Parachilna gorge, Blinman and Wirrealpa.

An Arundel plot was used and the scale of the southern run adjusted

to the more northerly one, the scale being approximately 1°6 inches to the

mile. The geological detail was transferred from the photographs, and for

the greater part checked by field work. It shows well the trend of the

Adelaide System in the area, and the disturbances which can be traced right

across the ranges from Parachilna to Wirrealpa. The 3 inches to the mile

*MARREE

Locality Plan

inset map of the centre of the larger map was compiled from oblique photo-

graphs by gridding and close ground checking, and relates an accurate pic-

ture of the topography and geological structure of the area dealt with in

this paper.

The detail of the sediments inside the intruded area has not been shown

as this portion of the dome is highly shattered flaggy quartzite not showing

any well-defined marker horizons.

STRATIGRAPHY

The detailed sections run were limited to the east and south of Alpana

homestead. The line of section submitted was considerably staggered in

order to avoid crush zones and soil cover. The upper extent of the beds

is the bottom of the hieroglyphic limestone horizon, and the strata recorded

on the following pages follow in downward succession.

Hieroglyphic Limestone

(1) Beds of considerable but unmeasured thickness above item (2),

Dip 36°

Slates

(2) 1,400 ft. Mostly green-grey, but passing to chocolate near upper

limit (average dip 27°).

Cryptozoonic Limestone

(3) 50 ft. Dip 17°.

ate

(4) 170 ft. Dip 20°.

167

Calecareous Sandstone

(5) 20 ft.

ate

(6) 270 ft.

Dip 22°.

Dip 23°.

Cryptozoonic Arenaceous Limestone (Mt. Emily). Total thickness 30 ft.

(7) 8 ft.

(8) 12 ft.

(9) 10 ft.

Shale

(10) 700 ft.

Arenaceous Limestone with small limestone bands a few

inches thick, which show extremely rich eryptozoonic hori-

zons. Dip 5°.

Impure and arenaceous flaggy limestone.

Massive arenaceous limestone with coarse intraformational

breccia.

Grey to green shales. Dip 10°.

Arenaceous Limestone and Standstones. Total thickness 339 ft.

(11) 91 ft.

(12) 53 ft.

(13) 18 ft.

(14) 20 ft.

(15) 48 ft.

(16) 32 ft.

(17) 9 ft.

(18) 8 ft.

(19) 31 ft,

(20) 29 ft.

Slate

(21) 400 ft.

Massive limestone with cryptozoonic horizons.

Sandstone with flaggy horizons,

Limestone commencing with a cryptozoonic horizon pass-

ing up into an intraformational breccia.

Massive quartzite and grit,

Flaggy limestone passing up into massive ctyptozoonic

limestone, flaggy arenaceous limestone.

Calcareous grit.

Flaggy sandstone,

Arenaceous limestone.

Limestone with eryptozoonic and gritty bands, including

intraformational breccia,

Quartzite becoming gritty and calcareous.

Finely laminated graded chocolate slates. Becoming cal-

careous. Dip 16°.

Arenaceous Limestones and Grits. Total thickness 563 ft.

(22) 50 ft.

(23) 47 ft.

(24) 43 ft.

(25) 232 ft,

(26) 6 ft.

(27) @ ft.

(28) 111 ft.

(29) 51 ft.

(30) 14 ft.

Shale

(31) 270 ft.

Calcareous grits passing up into massive limestone with

cryptozoonic horizons.

Limestone, commencing with an arkosic grit becoming

pelleted.

Limestone with excellent cryptozoons in the purer bands.

Ends with an intraformational breccia.

Blue limestone with a wavy structure passing up into

quartzite.

Buff limestone,

Arkosic grit.

Massive limestone with good cryptozoonic horizons.

Arkosic grit passing up into calcareous slate.

Arkosic grit with interbedded sandstones passing up into

a pelleted and cryptozoonic horizon. Pieces of angular shale

occur in the intraformational breccia.

Shale, finely laminated with occasional quartzite bands.

Dip 18°.

Limestone. Total thickness 200 ft.

(32) 127 ft.

(33) 10 fet.

(34) 63 ft.

Massive blue arenaceous limestone with cryptozoons.

Flaggy sandstone.

Arenaceous limestone, both flaggy and massive, passing up

into a cryptozoonic horizon,

168

Flaggy Quartzites. Total thickness 358 ft.

(35) 158 ft. Yellow to green finely laminated flags with quartzite bands

in the upper limits.

(36) 3 ft, Grey arenaceous limestone with wavy markings.

(37) 55 ft. Massive and flaggy quartzites. Dip 20°.

(38) 30 ft. Flaggy quartzites. Upper limit is terminated with a one

foot band of blue oolitic limestone.

(39) 10 it. Calcareous shales.

(40) 12 ft, Flaggy quartzites with a four foot oolitic limestone horizon.

(41) 38 ft. Quartzite becoming buff coloured, flaggy with ripple marks.

(42) (43) 52 ft. Quartzite tipple marked at the top.

Slate. Total thickness 874 ft.

(44) 185 ft. Flaggy slate readily splitting into large flags.

(45) 218 ft. Slate—a little arenaceous.

(46) 231 ft. Slate. Dip 34°,

(47) 240 ft. Slate, slightly calcareous at base then becoming arenaceous,

occasionally showing cross-bedding.

Flaggy Slates and Limestones. Total thickness 153 ft.

(48) 10 ft. Intraformational breccia limestone,

(49) 2it. Flaggy quartzite.

(50) 2 ft. Flaggy limestone.

(51) 2 ft. Flaggy quartzite.

(52) 50 ft. Flaggy limestone.

(53). 28 ft. Sandy slate.

(54) 2 ft. Blue limestone.

(55) 25 ft. Calcareous slate.

(56) 7 ft. Limestone.

(57) 15 ft. Flaggy quartzite.

(58) 10 ft. Grey-blue limestone, 'as intraformational breccia.

Flaggy Quartzites. Total thickness 1,250 ft.

(59) 70 ft. Quartzite becoming flaggy.

(60) 550 ft. Flaggy quartzite.

(61) 420 ft. Massive quartzite.

(62) 41 ft. Flagey sandstone.

(63) 149 ft. Sandstone with dark bands. Dip 56°,

From here the thicknesses of the underlying beds are difficult to deter-

mine with any certainty, but the general sequence is slate, melaphyre, slate,

dolomite, quartzite and flaggy quartzite showing ripple marks, pseudomorphs

after halite and slaty bands,

There is a direct correspondence from 1 to 10 of the above section

with 41-34 of Mawson's Brachina Creek Section some 30 miles to the south,

and it seems likely that the quartzite ridge surrounding the dome (including

Mt. Elkington) would correspond to the greywacke horizon indicated in

Mawson’s Structural Map of the Flinders Ranges. Taking it as such, the

centre of the dome corresponds to the slate, arenaceous slates and flaggy

quartzites overlying the Sturtian tillite and accompanying grits.

The variation in the thickness of the rocks in this area as compared

to those at Brachina Creek area is considerable, as is seen in the thickness

of the stibmitted section, 4,410 ft. as compared to the corresponding 3,280 ft.

at Brachina Creek.

169

DIASTROPHISM AND ACCOMPANYING INTRUSIONS

The Blinman dome has a peculiar feature in that, ringing about tts inner

20 square miles is a pronounced ridge of flaggy quartzite within which a zone

of great shattering and faulting occurs. From a brief study of the accom-

panying map this zone is readily distinguished, as into it have been intruded

the dolerites of the district. The belt is approximately one mile wide and

runs parallel to the above mentioned ridge, leaving a folded central core

or area less disturbed and free of intrusions.

BLINMAN ~ Mr EMILY SECTION

SCALE dm faet

Coupled with this it is found that the greater part of the dome, except

the south-west block, shows a pronounced increase of dip in the last 800-900

yards approaching the perimeter ridge. Thus there is an increase of 50°,

from 20° at the Youangera Springs horizon to 60-70° degrees at the ridge

itself. In the north-east section of the dome, the effect reaches its preatest

intensity where the beds are tilted from 23° up to 85° overturned: This

represents an increase of over 70° in a distance of 700 yards or less,

This structure is similar to that of the island of Arran, Tyrrell (1928),

where the sediments consist of an arenaceous series including the lower Old

Red Sandstone, a lower group of sandstone and basic lava, tuits, red shales

and marls. These sediments are assumed to have been flat-lying Mesozoic

rocks lymg on Dalradain schists and post schist sediments without any

angular unconformity. During the Cainzoic a great boss of granite, radius

four miles, intruded the area and now forms the nucleus of North Arran.

The granite intruded the ring of Dalradian schists, and where their strike

was S.W. to N.E. with a dip predominantly to the S.E. it was steepened,

and on the other side of the intrusion where the sediments were originally

towards the granite, the uplift overturned the sediments so that they dipped

away from the intrusion. This is well seen in sections across North Arran.

NORTH ARRAN SECTION

00 YDS. —— —— —— ——

Reed onAnite’ Fo dscnist fF Sjouwreoss. ESSrusr Egy] sasact

However, the point which is to be emphasised is that the structure of the

sutrounding sediments is clearly dependent on the intrusion. In general,

the strike of the adjacent rocks curves in uniformity with the granite margin.

Their dips are outward: steep for a distance up te a half mile before they

gradually falt back to their low angle. See Section.

170

Comparing the Blinman area with Arran, there seems to be a direct

analogy. Though the centre of the Blinman dome is not occupied by a mass

of igneous rock, nevertheless it is clearly seen that to form the structure

that now exists there must have been a great force from beneath to lift the

sediments into their upturned position and cause a circumferential belt af

shattermmg perforated by dolerite intrusions, It suggests the emplacement

of a large basic igneous body which has been arrested while plugging a

central core of sediments upward. In age the intrusion would have followed

a late stage of the Cambrian to Post Cambrian folding and allied faulting.

Only the morte obvious faults were mapped and those few, together with

others not indicated, are nearly all Jocated along the axes of two strtictural

bulges which are located one either side of the dome.

The possible sequence of events suggested is as follows: The tectonic

forces which originally acted on the- Adelaide System sediments in the

Blinman region were not completely relieved by the formation of a simple

domal] structure and a coupled force developed giving rise to the two struc-

tural bulges mentioned. This couple set up crushing and faulting move-

ments at the apex of the dome, while part of the stress took relief by faulting

along the axes of the bulges.

The ultimate fracture of the apex of the dome allowed the periclinal

sediments to be buttressed and upturned against the central core, In this

way the stresses would have been finally relieved and the path prepared

for the emplacement of the igneous mass from beneath. Fig 1 represents

the likely cross-section of the structure.

a FIGURE 1. SSE

The diastrophism causing this phenomenon and the time of the intrusion

would appear to have been considerably Post-Cambrian. Support for this

fies in the fact that the shattering of the dome has been at comparatively

shallow depth, as indicated by the predominence of crushing and shattering

overt the occurrence of fold phenomena. Even the shales have tended to

shatter into large blocks in a finer matrix. It is not conceivable that this

condition could arise if 20,000 to 30,000 ft. of Adelaide System and Cambrian

sediments were superimposed on the beds in question. Therefore there must

have been a considerable period of erosion after the upheaval of these sedi-

ments in Cambrian and Post-Cambrian times before the conditions neces-

sary for the development of the structure could arise.

To suppose that the central core was of an older age, folded, faulted

and intruded before the deposition of the remainder of the Adelaide System

would infer an unconformity which should be clearly evident. Moreover,

this suggestion could not explain the unintruded central core.

171

EFFECTS OF RESIDUAL STRESS ON INTRUSIONS

The general shattering and brecciation with little folding even in the

slates and shales, and the formation of the present conditions at shallow

depth, would not have been accompanied by a uniform pressure over any

area. On the contrary differential pinching on the sediments according to

varying stresses, is the only explanation of the origin of the coarsely foliated

bi-mica schists and gneisses associated with many intrusions (see p. 187).

A following period of iow grade stress must have persisted for a great length

of time, with intermittent revivals causing brecciation of isolated dolerite

bodies, as in the case of locality 96.

Noe TI

Pioege a eae

or Se eee aN

in|

A dv equa ca \ es \ pu [at abe ott

\ bea fore me Ee ft

EMER Na ee. Fendi

2 he BLINMAl

.”

ramet

GEOLOGICAL MAP “xc

OF THE ~~

BLINMAN AREA

> >

eewt er Ie meee es

FLAGGY QUANTZITE

EACCAREOUS FLAGS W LIMEDTOND

FiaGayY GuAATJI 8 WITH DOLOMITIC A SLATY: ban

BASIC jonrols iWIKUSIVE

BASIC SAHEOUS pritinive

TRACK

nipee

However, in general the dolerites do not show many effects of severe

stress such as the bending of felspar lathes, granulation or actual brecciation,

but the slow destruction of their original textures and their highly altered

composition serve to indicate that a low grade stress insufficient to imparz

a new type texture was operative.

An interesting occurrence of acid rocks in the area is seen at locality

157 and 172, where there are coarse pegmatitic rocks. 157 is hypidiomorphic

172

granular containing a large number of accessories, and may represent a late

phase of extreme differentiation of the basic magma. This is possible as

such occurrences are few and their size comparatively small.

At locality 172 is a small reddish granitic gneiss, which was referred to

as granite by Howchin (1922). Microscopically it is very similar to the

pegmatite of locality 147, except in its gneissic structure and greater amount

of biotite: it appears to be the stressed equivalent of that at 147. These

two would presumably have been intruded well after the dolerite, one accom-

panied by a pinching and the other not, showing that the differential stresses

were still operating. Post crystallization granulation of these two rocks

points to repetition of stress at a still later period,

FIELD RELATIONS OF BASIC ROCKS

The melaphyres are intraformational and thus belong to a much earlier

period of igneous activity than the dolerite bodies which are found intruded

into the overlying younger sediments. The highest point to which the

dolerites have penetrated the System and the horizon of the flows may be

judged by their relative positions to the perimeter ridge, which is approxi-

mately stratigraphic. The dolerites intrude the ridge horizon at Mt, Elking-

ton, while at South Blinman the flows are 1,000 to 1,500 ft. lower in the

system. The dolerites of South Blinman are also clearly above the flows.

The eatth movements causing the shattering and brecciation before and

curing these intrusions were responsible for the frequent faulting and cut-

ting out of melaphyre beds, and in some cases their overturning as at 119.

eis bed ts overturned $° to the E.S.E. but remains parallel to the regional

strilce,

Though the melaphyres can be distinguished at intermittent intervals

about the dome, they are scarce in the west arid north, and are concentrated

mainly in the S.E. This indicates that the flows were not of 4 regional

scale but confined in extent about their source.

Occurrences at 119, 120, 112, 113, 82 and possibly 79 and 78 appear to

be the same flow at different points. They consist of two parallel flows at

closely separated horizons. In each case no jensing or variation of thicknéss

could be distinguished. In these and the others, averlying ash beds, are very

limited and measure only a few inches in thickness. They grade into arkoses

containing actinolitic and chloritic material, to chocolate sandstones, to

chocolate slates, and finaily into grey and purple shales.

Sandstones are found underlying the melaphyres at 112, 82 and 79, and

are current bedded. However, these do not appear to be universal, indicating

the varying conditions over a small area under which the fows were laid

down. Shallow water and arid conditions were common in the area as a

whole, as can be judged by the underlying sediments, which consist of grey

slates showing ripple works and halite pseudomorphs. These grade up into

tipple marked quartzite and sandstone bearing halite pseudomorphs and

lines of current bedding indicated by ilmenite grains.

As no pillow laya structure is evident, it seems likely that these

deposits were caused by fissure eruption on to flat-lying lake beds, dry or

nearly dry. That the mechanism of eruption was by fissure flows is sup-

ported by the small amount of ash and tuff in the area. In several areas,

such as 78, 85 and 77, amygdaloidal melaphyre is actually interbedded with

very thin bands of shale, sandstone and other sediments, so that there must

have been either submarine or shallow water conditions. In the case of 78,

the large spheroidal shapes of weathering melaphyre in situ suggests former

173

pillow structure, but in its weathered condition it is difficult to tell. The

total thickness of basalt, its amygdaloidal counter part, and interbedded

sediments, is upward of 300 ft., and is quite similar to 77.

77 is a very complex hill capped with brecciated fine grained basalt,

which appears to have been intruded by later dolerite found about it in

numerous small off-shoots, Proceeding N.W. from the summit amygdaloidal

melaphyre is interbedded with bands of sediments which eventually pass

up inta purple shales, To distinguish these rocks as spilites under the

microscope is quite difficult, because the stresses which have operated on the

area have effected destruction of the felspar with the production of very

little epidote, while the felspar or tesidual felspar is often albite. Thus the

original compostion of the felspars need not have been very basic nm com-

position.

At locality 71 is a fine-grained intraformational basalt clearly conform-

able with the tinderlying sandstone and this in thin section is wholly albite,

chlorite and magnetite. and possibly represents a spilite, In the field no

pillow structure can be detected.

This is a class of fow which is quite distinct from those seen at localities

82, 112, 72, 119 and others, where occurrences are obviously sections of one

and the same flow, having the identical amygdaloidal rock resting on a

chloritic sandstone. The base of this melaphyre formation there is a highly

scoriaceous zone where, possibly, it contacted a cold or wet surface. This

is followed by a more compact phase with lines of drawn out vesicles parallel

to the base, indicating flowage. Nearer the top the sceriations become

greater to atl extreme degree at the surface, and are then followed by a few

inches of ash, a foot or so of chloritic arkosic rock, and so of as mentioned

previously, The thickness of the four outcrops is constant at approximately

140 ft. In the case of 119 and 112, and possibly 82, there are two Hows, the

upper one separated from a lower body of melaphyre by over 400 ft. in the

case of 119, and over 300 ft, at 112, of slaty sediments which are mostly soil-

covered,

Feeding pipes or yents from which these flowed were not found. It is

possible that their rock type is so familiar to the fine-grained dolerite as

to have passed detection. Locality 77 could bear re-examination in that

light.

As the later dolerite intrusions took place inta extremely shattered areas,

their shapes naturally tend to be irregular. Thus the oceurrence of anything

but short, ill defined dykes is uncommon. The only good example of 2

dyke is at locality 165, where it is seen vertically disposed crossing several

erecks jn a N. 265° trend, This body is 40 ft. wide and has a length of

approximately 200 yards. The contacts are clearly defined by white bands

of decomposing fritted edges.

Less well defined bodies occur at localities 149, 69 and 68, and in all

cases they are comparatively short in length as at locality 68, where the dyke

is eight yards wide and thirty yards long. This outcrop stands out as a

ridge three feet high and has weathered into spheroidal boulders. Localities

149 and 49 are cases where the contacts are not good but the widths of out-

crop are maintained for the observed lengths of the bodies, 50 ft. and 120 ft.

respectively,

Howevet, the shape and specific form of most intrusions are nondescript.

They occur either as slightly elongated bodies, lenticular in shape, or more

commonly as sub-circular bodies with brecciated sediments drawn round

them hy the uplift of the intrusion. Creeks transecting such lenticular or

sub-circular bodies give, at times, the impression of a dyke, The majority:

174

of the outcrops referred to as dykes by Howchin (1922) are thought to be

slightly elongated dolerite plugs. In some instances lines of weakness are

intruded by a number of such bodies separated by intermittent zones of bréee-

ciated sediments. Examples of this are seen at localities 64, 65, 66 and 96,

In the former case 64 and 66 are concordent with unbrecciated sediments

and thus approximate to a sill structure.

A similar type of body is seen to the south at Enorama. Here many of

the bodies ate semi-concordant injections elongated parallel to the general

strike of the sediments in the surrounding atea, The largest of these lenti-

cular plugs is approximately one mile long and 700 ft. across at the widest

point. Smaller bodies are joined by subsidiary dykes and stringers, so that

what appear as a series of distinctly unconnected intrusions on the surface

are probably a single concordant intrusion at no great depth.

MINERALOGY

The Blinman dolerites ate composed of basic plagioclose, stub-calcic

augite, pigeonite, plus or minus olivine. Magnetite, ilmenite and apatite

are primary accessories, Late dueteric minerals comprise quartz, albite,

while anorthoclose may be present in some instances, but its presence is

difficult to distinguish under the ordinary microscope due to its small size.

Because of the universal alteration of the minerals by saussuritization and

uraljtization, details of minerals become more descriptive in nature than

specific optical data.

PLaGIocnase

This mineral is marked by brown dusty inclusions which are found in

nearly all the older basic rocks of South Australia, including the Musgrave

Ranges, the Barossian Complex of the Mt, Lofty Ranges, and in certain of

the intrusions of the Flinders Ranges,

These inclusions become particularly dense in some instances, and

resemble near-basal sections of biotite. Such inclusions are described in rocks col-

lected by Wilson (1948) from the Musgrave Ranges. In all these cases inclustons

are expelled immediately recrystallization commences, and thus it is a useful

guide in determining whether or not a plagioclase has suffered recrystalliza-

tion, or to what degree, as judged by the clear peripheral zone about the

dusty brown core. In cases such as the labradorite of the somewhat meta-

morphosed basic igneous rocks of Woodside (Mt. Lofty Ranges), which is

quite clear, it would be inferred that though it may still have a composition

close to its original one, it has, nevertheless, been regenerated.

Suussuritization with concommittant regeneration of plagioclase to a

more acid yariety is so common that there is little chance of determining

how basic the composition originally was. Rock (9016) illustrates the least

affected pagioclase found in the area, This has a maximum basic camposi-

tion of Ab,,An,,, which is only mid-labradorite, Zoning is obliterated at an

early stage. Rock (9016) is ane of the only examples where zoning is

retained. In it successive zones in the plagioclase lathes range from Ab,,An,,

to Ang sAny,.

The predominant composition js acid andesine to oligoclase, the latter

being untwinhed and of low relief, approximately equal to balsam.

The average size of the lathes is 1-3 mm. * 0-4.mm., and up to 7 mm. *

1 mm., in the gabbroic types,

Saussuritization has given rise to great quantities of epidote, clinozoisite

and zoisite with a little seapolite in a limited number of sections. Calcite

is in some cases quite prominent, White micacecus matter is occluded

within the plagioclases and appears to have formed during the same process

175

which gave rise to the epidotes. Although usually colourless it is some-

times seen in shades of light green. E, B. Bailey and G. W. Grabham, in

their paper “Albitization of Basic Plagioclase Felspars" suggest that this

mica results from a late deuteric introdtisction. However, it wonld be more

logical to assume that it is a soda mica such as patagonite, which has come

from the plagioclase enclosing it. In so many cases it is the chief alteration

product and forms in such a manner as io cast little doubt as to its secondary

origin. In altered lathes it is found either parallel to the basal cleavage or

to the “c” axis, that is, the length of elongation. These phenomena are best

seen in the slides of rocks 9017, 9034 and 2823.

‘The efidote usually forms in much larger grains than docs the zoisite

and, at times, it is strongly pleochoic in yellow-greens, Cleayage may or

may not be evident as in the epidote of rock (9015}, where it occurs as

remarkably large anhedral to subhedral crystals free of cleavage and frac-

tures. Biaxial (— ve) with a large optic axial angle of 80°.

Zoisite always forms in rather smal! grains which are not large enough

to yield optical figures. Odd grains are biaxial (+ ve) with a low 2V in

vicinity of 40°. It ts must readily distinguished from the epidote by tts lack

of pleochroism and its lower birefringence often showing anomalous effects.

Clinvzoisite is common, and it is possible that, as it also shows a low

birefringence and anomalous biues like zoisite it may accut more frequently

than supposed. In sufficiently large grains it is readily distinguished by’ its

biaxial + ve figure, 2V=80°. In the case or tock 9020, a phenocryst of

felspar has been completely replaced by clinozoisite.

PYROXENES

Augite—This is not common, but where it occurs has a 2V (+ ve) of

45-60°. An accurate range of Z Ac cannot be determined without the use

of the universal stage, but it is probably about 39°. The size is as with the

other pyroxenes from 1°9 mm. * 0°50 mm. to an average of 0°90 mm. *

0:40 mm.

Sub-calcic augite is the predominant pyroxene and is taken as ranging

from 2V 35/45 degrees. Z Ac 37/41 degrees. Twinning is not common,

and at times a faint pleocoism is evidenced. X = faint fawn, Y = faint pink,

Z = yellowish fawn. The crystals are subhedral to anhedral, occurring

intersertally between the interlocking plagioclase lathes, or giving ophitic

textures when crystallizing after the plagioclase. Generally the ophitic

textures are poorly developed,

Grain sizes are above average, 0-9 mm. X04 mm. The ophitic host

crystal in a slide of (9033) is 8 mm. in diameter,

Pigeonites—There is little ohvious distinction between these and the

more caleic varieties, except for their optic axial angles, which fall into a

range between 12 and 35 degrees.

Uralization in its earliest stage is seen in the slide of (9016), com-

mencing at the edges of the pyroxene as a green coating giving a marked

change in birefringence from middle second order down to first order greys

and yellows. Prismatic form showing 120° cleayage makes an early appear-

ance, but in general the alteration is from the predominantly elongated

pyroxene lathes parallel to “c” axis, and the resulting amphibole is conse-

quently also in lathes, needles and fibrous felted masses of elongated habit.

Concommitant with this is the release of brown-green biotite in odd frag-

ments, In other cases, such as in rocks 967 and 9034, there has beer a very

abundant release of magnetite into smail grains aligned in well defined

parallel lines, representing cleavage or partings. The most common amphi-

176

bole resulting from the uralitization has a moderate optic angle which ranges

down to 40° and below, and up to approximately 60°, orrespanding ta

hornblende. Actinolite also occurs, having < higher optic axial angle of

70/90 degrees. The maximum extinctions, though varying from 12/23

degrees, are almost constant at 15/16 degrees.

The colours vary according to the composition. The most common is

a light coloured mineral which is only faintly pleochoic: X =near colourless,

¥=light brown-green, Z=light green. Through gradations of deepening

colours some yarieties are found to be distinctly blue as in rocks 9020 and

2823, where X = light green to colourless, Y = blue green, Z = blue, and

2V =40°, The ZAc seems to be much the same as the more common

hornblende, t.e., approximately 15°. Alterations of this type have been met

with in Canada, New Zealand and elsewhere, and will be mentioned later

under the heading of petrology.

It is common in some places to find destructive weathering of the

dolerites as with rock 9012, and in such mstances the most common minerals

formed are chlorite and calcite. Light green hornblende may be found in

needle-like form intergrown with chlorite and calcite, Distinction between

the amphibole and chlorite is determined by the signs of elongation, the two

being opposite. This is very useful, at times they appear to be the one

atid same mineral.

OLIVINE

Pseudomorphs after olivine are found in a considerable proportion of

the rocks, but in no case is olivine itsel€ found, ‘The pseudomorphs are

mostly magnetite together with antigorite or talc. The magnetite, in many

cases, preserves the original idiomorphic outlines and indicates the irregular

cracks and fissures common to olivine, .

Minor CONSTITUENTS

Under this heading may be referred the granophyric intergrowths and

accessory minerals, The introduction of quartz-albite as interstitial inter-

growths is of late magmatic origin, aud will be referred to under the petro-

logy.

Magnetite and ilmentte are the two main minerals to be mentioned here,

The exact proportion of primary magnetite cannot be determined at all

because of the release of large amounts during uralitization. The ilmenite,

though not distinguishable from the magnetite when fresh, readily shows

once alteration to lencoxene occurs. This takes place in several ways.

Firstly as a peripheral ring, and secondly as complete alteration, giving rise

to disseminated prains and stringers of leucoxene. On recrystallization these

five rise to latger grains, and might be better called sphene. The third mode

of alteration is seen in the large ifmenite grains, and takes place along definite

parallel planes, possibly corresponding io crystallographic symmetry,

Pyrite is seen in many of the hand specimens, and sometimes figures

quite prominently.

Apatite is quite abundant in some rocks, but on the whole is not common.

It ig found in small rods and prisms in the rocks which have suffered most

deuteric introductions.

A host of secondary minerals such as zoisite, clinozoisite, epidote, seri-

cite, tale; chlorite, antigorite limonite, iddingsite, scapolite and albite occur,

but have been mentioned in connection with the minerals from which they

arose.

The mineralogy of the melaphyres bears a separate mention as they art

of a different age and differ in many of their properties.

177

PLAGIOCLASE

Here no cases of dusty brown inclusions have been ijound, and whether

they ever occurred cannot be determined. The plagioclase has been in all

cases regenerated to acid andesine and lower, and only one instance of labra-

dorite can be found. The determinations of the R.L in relation to balsam

is particularly difficult, as decomposition products crowd the edges suffi-

ciently to confuse the true nature of Becke’s bright line. The method using

the intersection of the basal cleavage against the twin planes is not possible

as regeneration has obliterated such evidence. As the extinction angles of

the twin planes in the symmetrical zones rarely exceed 16° it is possible that

the plagioclase could be albite. On the other hand, twinning is strongly

developed, and seems too regular and coarse for an albite composition.

Baveno twinning is strongly develaped in places.

Unlike the dolerites, comparatively little epidote occurs, and instead the

predominant secondary mineral is clear white flecks of mica oricntated

parallel to the twin planes. Where epidote occurs it is usually recrystallized

into larger pleochroic crystals.

Pyroxenes are completely lacking and amphibole is not abundant, quite

often being replaced by chlorite. Generally speaking the melaphyres are a

felspar-rich and ferromagnesian-poor rock.

Olivine again occurs only as pseudomorphic magnetite, chlorite, anti-

frorite and limonite, but is more clearly distinguished as residual olivine than

in the case of the dolerites.

Minor Constituents that were not contained in the dolerites include rutile,

haematite and anorthoclase. The fatter is found in rock 2829 fram South

Blinman and is a late deuteric introduction.

Associations are muscovite, cholirte and quartz. More usually the intro-

ductions are of albite and not anothoclase. Rutile only forms in small grains,

too small to show cleavage, but its red-brown colour and adamantine [ustre

in reflective light readily distinguish it.

Haematite ig common as micaceous Jinings in amygdales. Where basal

sections occur its ted nature is discernible, otherwise it appears quite similar

to the magnetite. It is also very common, filling joint fissures with regular

patterns,

PETROLOGY

During crystallization there has been mormal soda enrichment in the

plagioclases and calcium enrichment in the pyroxenes. However, as most

specimens have been considerably altered very little detailed observation im

this direction could be attempted.

The order varies in specific instances, but in general the first mineral

to crystallize was olivine, followed by the pyroxene with slight overlapping

of the plagioclase as evidenced by the tendency towards sub-ophitie texture

of felspar lathes imbedded in pyroxene. In rock (9033) there is the only

instance of true ophitic texture where the plagioclase has crystallized and

later has had the pyroxene crystallized about it.

The crystallization of sub-calcic augite appears ta precede the pigeonite,

which in all cases occurs as small residual crystals in the finer mass of the

rock,

The course of crystallization of the minor constituents is obscured by

alteration and late deuteric introductions, which include [{1) replacement

effect of albitic solutions on original plagioclases, (2) introduction of quartz

178

or quartz-albite and anorthoclase on rarer occasions, (3) introduction or

reintroduction of chlorite, biotite, and actinolite in vesicles of the melaphyres,

One important change, commencing in the late magmatic stage, is the

alteration of the pyroxene to amphibole. Though the majority of the cases

give rise to hornblende or actinolite, some show variation in the blue variety

with 2V (+ ve) of 35 to 40 degrees. This low 2V, if it is so, could be

explained by the introduction of a sodic glaucophane or riebeckite molectile

or by the absorption of the sodic element of secondary albite as in the case

of rock (2823), where the amount of plagioclase remaining after the break-

down in calcite, epidote and sericite is negligible. Such low 2V amphiboles

are not uncommon, and have been mentioned by Winchell from New Zealand,

and again by Hutton (also in New Zealand rocks). Bateman, in his article

on “Gold Deposits of Urchi Goldfields,” mentions occurrences of sodic amphi-

bole as possibly due to hydrothermal introduction of sodic molecules.

CHEMICAL ANALYSIS

Rock (9010) from locality 183 was chemically analysed with the

following result.

SiO. - <= 48-11 per cent.

ALO; += - 15°08 ,, ,,

FesOs ee =| 4°73 7 ” NORM

FeQ = - 837 4 wy Orthoclase - - 8-34 per cent.

MgO - - 5:87 , » Albite - = © 27797 yon

c30 - - G75 , 4, Anorthite - = 2146 , 4

NaO - - 3:33 , 4» Nepheline - - 28 , wy

KO - - 145 , 4 Diopside - + 2-55 , 4

H30+ - - O72 , 4 Olivine - - - O21 ,

HiO— - - O17 , 4 Calcite - - - 100 , w

CO, - - 044 , 45 Magnetite - - &73 4 ow

TiO, - - 210, 4» Ilmenite - - - 3°95 , y

S - - += 19 , 4 Pyrites - - O36 , 4

MnO - - O12 , 4 Water - - +» O89 , »

100-43 100-54

PETROGRAPHY

As pointed out, the Blinman melaphyres. and dolerite intrusions have

suffered a long period of intermittent low grade stress. This stress varied

sharply from point to point due to the nature of the shattering, and conse-

quently some dolerite bodies suffered little stress at all, as in the case of

rock (9016), while others, as rock (9034), suffered a considerable amount;

that is, greatly altered by saussuritization and uralitization. Between these

two extremes there is every gradation. Though not strictly accurate, a

normal classificaion is followed, based on the presence of pseudomorphs after

olivine and the residual textures,

Doreritic GABBROS

Few in number and show little variation: 9017, 9034, 2823.

DOLeERITES

A Olivine free

(1) Ophitic texture: 9033, 9015, 9036.

(2) Sub-ophitic to intersertal: 9016, 9020, 9021, 9028.

(3) Relic textures; B301, B59, 9029, 9012.

179

B Olivine bearing

(1) Ophitic texture: 2830, B135, 9011.

(2) Sub-ophitic to intersertal textures; 2832, M013.

MELAPHYRES

C Amygdaloidai

(1) Olivine free: 9018, 9014, 9026, 9031,

(2) Olivine bearing: 9027, 9024, 9022,

D Fine grained non-amygdaloidal : 9023, 9025, 9030, 9035, 9032.

Doieritic GABBROS

These coarse grained rocks are not common in the area and are confined

to localities 202 and 38. Of these, locality 38 is the only large mass, and

may represent the upper extention of a larger underlying mass.

Rock (9017) of locality 202 is a remarkable, coarse grained, whitish-

grey, gabbroic rock with specific gravity 2-894. In thin section the rock is

holocrystalline, hypidiomorphic tabular with a conspicuous granophyric inter-

growth between the interlocking crystals. The grain size is ayerage at

3:8 mm. X 1-0 mm., but individual lathes reach lengths of 8-O mm.

Plagioclase with a modal figure of 56% is in tabular form and is highly

altered so that multiple twinning is now indicated only by micaceous decom-

position products along the former twin planes. The alteration products

are sericite, zoisite, epidote and scapolite. The latter occurs as disseminated

flakes showing cleavage and straight extinction, and therefore difficult to

distinguish from sericite. However, sections without cleavage are more

easily determinable, giving uniaxial (—ve) figures. The epidote is pleo-

chrojc in yellow-greens and has a distinctly higher birefringence and

occuring iti larger masses than the zoisite, in which the lower order colours

are matked by anomalous blues, Where residual twinning is seen in the

felspar, it has extinctions up to 15°, with R.I. less than that of the Canada

balsam. It is best seen in peripheral zones with twin planes far apart, where

it is biaxial (t+-ve) with 2V'=70°, and thus is Albite.

The uralite, which has a modal occtirrence of 37%, has resulted from the

breakdown of the original pyroxene and some residual properties such as

twinning still remain. Uralitization has given abundant release of magnetite

along parallel planes of the pyroxene, and these may represent original extra

partings as seen in diallage or an exaggeration of the schiller structure as

seen in bronzite. The alteration does not appear complete, but 120° cleavage,

with extinctions of 16°, are to be observed. The interference figure is biaxial

(—ve) with a moderate 2V. Pleockroism is weak in shades of green when

the replacement is complete, otherwise it is near to colourless, and poikiliti-

cally includes magnetite and epidote. The light colouring would seem to

be partly due to the expulsion of the abundant iron during the uralitization,

Magnetite (apart from that contained in the ferromagnesian constituent)

has a modal figtire of 31%, of which a fair proportion would be primary.

Grains show octahedral and rhomb form, and include crystals of clear non-

pleochroic epidote and brown rutile. Chlorite and limonite are accessory.

Granophyric intergrowths occupy the junction region of large crystals

and are of late formation. The modal occurrence is 41%, of which quartz

is 2-2% and felspar 1°9%. The growth is of albite in a quartz base, the albite

showing multiple twinning with extinctions of 12°,

Rock (9034) from locality 38 varies from the previous rock in degree of

alteration, Complete saussuritization, sericitization and regeneration of the

188

plagioclase have obliterated all signs of twinning. Residual felspar is

untwinned albite-oligoclase: biaxial (+ ve), 2V =70°. The Uralitic amphi-

bole is colourless to X = light brown, Y = green, Z = blue-green. Imenite

ig in skeletal forms in the process of break down tu leucoxene. Individual

crystals of epidote are larger than those of the zoisite. Biotite and rutile

occur.

Rock (2823) was collected by Howchin and labelled “Dyke West of

gneiss, 1 mile West of Blinman”. This corresponds to locality 140 on the

accompanying map. Microscopically, this is similar to the foregoing speci-

mens, except the original twinning is indicated only hy the parallel orien-

tation of the mica with respect to the old twinning planes, The Uralite has

pleochroism such that KX—=light brown, Y=deep green, Z=blue. The

optic axial angle is (—ve) 2V.=40°. Alteration of the hornblende has

ytelded chlorite and epidote. Secondary magnetite has suffered hydration

to limonite. The granophyric intergrowth is prominent.

DOLERITES

Al—Olivine-free zolerites

Rock (9033) is a grey porphyritic variety in which the pyroxene may he

distinguished, set in a medium grained base. It is from locality 86.

In thin section this has an ophitic texture with the felspar laths set

in phenocrysts of pyroxene. The larger pyroxenes are glomerophenocrysts

of commonly orientated crystals which have altered along cleavage planes

and lines at 90° to them. Composition varies from pigeonite (+ ve)

2V =25/35 degrees to sub-calcic augite (+ ve) 35/45 degrees, The plagio-

clase is represented by a typical saussurite mass containing untwinned acid

plagioclase. The uralite occurs in fibrous and acicular aggtegates; X = light

brown, Y = green, Z = blue, Z Ac 12°, It is usually intergrown with light

green aon-pleochroic chlorite.

Accessories include odd grains of calcite, deuteric quartz, apatite, pleo-

chroic biotite (X = light brown, Y= Z= strong brown), secondary magne-

tite and primary ilmenite in skeletal grains giving rise to leucoxeme.

Rock (9015) from locality 174. Microscopically the rock is holocrystal-

line with an ophitic texture. The plagioclase is strongly coloured by brown

inclusions, which are expelled in the peripheral zones where regeneration

of the mineral has been effected. Zoning shows from Ab,,An,., labradorite

to Ab,.An,,, andesine.

The uralite is light coloured and similar to the previous reck, Deeper

colours occur in patches within the lighter variety, which has a somewhat

higher Z Ac of 18°. Again the optic angle appears to be somewhat lower

than normal hornblende,

Sub-calcic augite is mostly broken dowti into uralite. Optic axial angle

varies from (+ ve) 2V =32° to (+ ve) 2V =45°, Z Ac = 38°.

Epidote, (— ve) 2V = 80° and lower, is non-pleochroic and shows cleay-

age where elongated, Tllmenite breaking down into sub-translucent mass

due to hydration. Magnetite is present,

Rock, (9036) is a medium grained dark grey specimen in which a fair

amount of green epidote may be detected. At South Blinman it is common

to find green flakes and needles filling joints and veins, and has apparently

originated by the removal of secondary epidote from the breakdown of the

calcie felspar.

In thin section it is holocrystalline with an ophitic texture, and ts

traversed by an epidote vein. The plagioclase, which is Ab,,Any,,, andesine,

shows little sign of brown inclusions. The extreme phase yields glassy clear

13]

plagioclase, R.I. < b; albite-oligoclase. The uralite is twinned. Z A c

28° and the optic axial angle (— ve) 75°. A different variety occurs in the

yein ag slender laths resembling biotite and chlorite with a maximum extinc-

tion of 16°. Chlorite is present. Epidote is both colourless and pleochroic.

Accessories also include skeletal grains of ilmenite, and sphene has resulted

from the recrystallization of the leucoxeme.

A2—Subophitic to intersertal dolerites

No, (9016), from locality [80, is a dark grey, compact, medium-grained

rock containing clear laths of fine felspar with multiple twinning and a black

ferromagnesian,

The plagioclase is elongated laths which are clear but for the brown-

pink inclusions, Zoning is such that the more calcic core has a maximum

extinction of 36° (Ab,,Ab,.), labradorite. Biaxial (+ ve) 2V'= 80°, while

the outer portions of the same crystals indicate andesine (Ab,,An,,)- The

probable average composition of these would be Ab,,An,,.. Twinning is on

two laws, albite and pericline with combined albite and pericline.

The pyroxene is a faintly pleochroic sub-calcic augite, X = faint fawn,

Y = pink fawn, Z = yellow fawn. The lowest optic axial angle recorded

was (+ ve) 37° at the rim and a maximum on the same erystal of (+ ve) 43°,

Simple twinning on the 010 is present, and a slight tendency towards plumose

structure is noticed. This is the only pyroxene present. Associated with

the pyroxene, as a product of uralitization, is amphiboles both in the fibrous

form and in prism sections showing 120° cleavage: pleochroism X = pale

brown, Y = green, Z = blue-green: optic axial igure (— ve) 80°: Z Ac 16°.

Biotite is associated and ts also strongly pleochroic from bright golden brown

to lighter shades.

The late deuteric (?) introductions include apatite as well as quartz.

Clear felspar ringing the more calcic variety is albite which has resulted fram

regeneration of original plagioclase.

-No. (9020) is a porphyritic dolerite from locality 147, In thin section the

former phenocrysts of plagioclase have been completely altered to clinv-

zoisite with a little mica. Sub-calcic augite also occurs in the phenocrystic

state.

The plagioclase has deep red-brown dusty inclusions, and does not

appear unlike basal sections of biotite. Composition is Ab,,An,,, indicating

aundesine- labradorite. Where the laths. have been included m the pyroxene,

subsequent uralitization has been strongest at the edges, and thus the plagio-

clase has its edges tinged by strongly pleochroic amphibole. Clinozolsite is

elongated patalle! to the “b” axis and shows oné strong cleavage parallel to

the 001. Extinctions from 0/5 degrees. Optic axial angle (+ve) 2V = 65.

The pyroxene Gccurs in two varietics, both of which faint pinkish fawn

to colourless, The stib-calcic yariety shows common orientation parallel to

the 010, devoid of cleavage. 2V varies fram (+ ve) 32° ta 45°, Values up

to 55° indicate augite. The common light green tralite occurs in fibrous

small lath aggregates. In it strong blue patches occur: X = light green,

Y =olive green, Z = blue. Odd extinction angles in it are considerably less

than 16°. Deuteric quartz is present.

No. (9021), from Jocality 141, contains pink to flesh-red felspar and ierro-

Mmagnesian minerals together with abundant tron ore, In thin section the

rock has an intersertal texture with occasional structureless patches. The

plagioclase is regenerated andesine (Ab,,An,,), which shows bent laths due

to stress.

The uralite is hornblende; biaxial (— ve) 2V = 60°; maximum extinc-

tion 30°, Pleochoism: X = light brown, ¥ = greenish, Z = bluish. Chlorite

+3]

182

and magnetite are associated, Hydration of the magnetite gives rise to

brown limonite. Accessories include ilmenite, leucoxene, strongly pleochroic

biotite and sericite. Apatite is very abundant as needles and stubby prisms.

The late deuteric (?) alterations and introductions are much more pro-

nounced in this section. Quartz is present as interstitial grains but has also

affected an intergrowth with untwinned felspar on the edges of the plagio-

clase laths, thus resembling myrmekite.

No. (9028) from locality 62. Micrascopically it is holocrystafline with

an altered intersertal texture. The plagioclase has suffered regeneration to

andesine (Ab,,An,,)- Further regeneration has resulted in glass clear acid

types together with mica epidote and chlorite.

The uralite is intergrown with chlorite. Associated biotite is strongly

pleochroic; X = light brown, Y = Z = olive green. Very fine skeletal grains

of ilmenite remain, together with much secondary magnetite.

Saussurite is very abundant. Epidote is in the larger crystals, being

biaxial (— ve) 2V = 80°, strongly pleochroic, elongated parallel to cleavage.

Its birefringence ts second order with some anomalous colours, which make

it yery similar to clinozoisite, which is biaxial (+ ye) ZV = 80°.

A3—Dolerites with relic textures

No. B301 is a dark grey rock from locality 96, where the outcrop is

brecciated in a crush zone. Phyllitic contact rock is veined with green fibrous

chrysotile.

In thin section the original texture has been entirely obliterated, giving

rise to a structureless mass of secondary minerals. The plagioclase is oligo-

lase. The uralite is light coloured: X = pale brown, Y = pale green, and

Z = pale teal-blue; it is very abundant as fibrous, flaky and lath-like aggre-

gates having oblique extinctions up to 15°, and intergrown with pale green,

antigorite and chlorite. The antigorite has very low birefringence, straight

extinction and opposite sign of elongation to the chlorite, Anamalous blue

chlorite is found in several veins ctossing the section. Pleochroie epidote

is abundant and pale brown to green pleochroic biotite is also present,

Timenite as skeletal crystals has given rise to translucent leucoxene.

B59, from locality 139, has a relic cphitic texture. The plagioclase has

been completely regenerated to low R.I. glassy albite-oligoclase, though some

andesine is still present in the sericite-zoisite-epidote pseudomorphs after

original calcic plagioclase,

The uralite is typical hornblende, and associated with it is fibrous, radi-

ating, length-slow antigorite. <A little pyroxene still survives as colourless

anhedral fragments bordered by zones of uralite. It is biaxial (+ ve), 2V

moderate, Z Ac 40°; augite.

The accessories are secondary except for ilmenite, which occurs in skeletal

grains. Zoisite in fine aggregates shows anomalous blues as distinct from

the epidote with higher colours and biaxial (— ve), Z2V=80°. Secondary

magnetite has resulted from the uralitization.

No, (9029), from locality 63, has a texture which is interlocking in

nature. The original plagioclase twinning is indicated by alteration along

parallel lines, corresponding to former twin planes. The alteration products

assume large sizes and specific properties may be determined.

The uralite has an optic axial angle of (— ve) 80°. However, the bluer

sections appear to be very much lower than the angle set for normal horn-

blende (52°). Magnetite and biotite are associated. Frayed fragments of

augite have optical axial angle of (+ ve) 2V =40°, Pigeonite, 2V = 25/35

degrees, is present.

Epidote and zoisite occur together, as already recorded. No leucoxene

is evident, and therefore the skeletal sub-translucent grains are taken to be

183

hydrated magnetite. Limonite occurs as dense red-brown amorphous

material.

No. (9012) occurs at locality 137, where the dolerite is finely jointed into

flags about three inches wide. From these joints destructive weathering of

the dolerite has taken place, giving yellow-green bands either side of a

normal dark grey medium-grained rock.

In thin section this holocrystalline rock is almost structureless. The

felspar is andesine (Ab,,An,,). The uralite is complex, due to destructive

weathering followmg uralitization. The amphibole is light coloured, shows

simple twinning and occurs mostly in needle-like aggregates: X = light

green-brown, Y = Z = light green; Z Ac 16°. The optic axial angle is

(—ve) 50°. This amphibole is intergrown with calcite and chlorite, the

latter exhibiting low birefringence and often anomalous blues.

Epidote is strongly pleochroic and has been recrystallized and segregated

from the original saussurite. The iron ore is titaniferous and has been

broken up into microcrystalline masses which grade into granules of sphene.

OLIVINE-BEARING DOLERITES

Bl—Ophitic olivine-bearing dolerites

No. (2830), collected by Howchin and described by Benson. This is

labelled “west side of Blinman mine,” which probably corresponds to locality

142. ,

In thin section it is holocrystalline with an ophitic and porphyritic

tendency. Pyroxene is abundant as colourless anhedral phenocrysts with

peripheral uralite: it is sub-calcic with an optic axial angle of (+ ve) 36/44

degrees, and has a maximum extinction af 44°.

The plagioclase has been completely altered to a colourless micaceous

mineral, and no regenerated plagioclase can be identified. A little epidote

is evident.

The olivine occurs as antigorite and talc (?) pseudomorphs, with the

production of abundant secondary magnetite, which outlines the former

idiomorphic form,

Rock (B135), from locality 201, is a dark grey medium-grained rock

containing blotchy patches of ferromagnesian minerals,

The rock has residual ophitic texture with plagioclase laths in process

of alteration interlocking within larger pyroxene crystals. The pyroxene

is colourless pigeonite, with an optic axial angle as low as (+ ve) 20°. Higher

values carrying it into the sub-calcic augite zone {Z Ac 35°).

The uralite is an amphibole which shows pale green colours and weak

pleochoism, but in many places the colour and pleochroism become marked:

X = light brown, Y = green blue, Z = blue. Here the source of the blue

amphibole seems to be late deuteric introductions along a fissure, for in the

immediate vicinity of the latter the pronounced bine colour appears. Possible

pseudormorphs after olivine are comprised of felted masses of light green

chlorite and antigorite associated with magnetite, which forms irregular lines

corresponding to original fractures.

The plagioclase is altered to a dense microgranular aggregate of zoisite,

epidote and sericite—epidote is often removed and recrystallized into large

pleochroic grains. The residual plagioclase is of low R.L. < balsam, and

shows occasional twin lamellae: composition, albite-oligoclase. Ilmenite

forms skeletal crystals with pronounced lines along which leucoxene has

formed, and it could he that these represent octahedral cleavage, along which

the alteration to leucoxene has been initiated. Sphene and magnetite are

accessory.

184

No. (9011) is a dark grey medium-prained rock containing laths of fine

felspar and black ferromagnesians, Found at locality 137. The felspar,

where stil] fresh, shows dusty brown inclusions as in (9016) and is labra-

dorite (Ab, Anya). Clinozsisite occurs in laths yielding biaxial (+ ve)

figures 2V =70°, Uralite is often porphyritically inclided in the felspar,

and though usually ight green more highly patches occur: X = light yellow-

brown, ¥ = olive green, Z = blue, Maximum extinction is 23°. Optic axial

angle is (—ve) moderate. Light green laths of chlorie and apatite are often

associated with the introduced deuteric quartz.

Pseudomorphs after olivine consist of magnetite and antigorite. Pyroxene

is stbordinate, and is seen only as anhedral residual laths that have escaped

uralitization. . tae

No. (2832) is a specimen collected by Howchin and later described by

Benson, Labelled “the dyke near the gorge, on the old road five miles west

of Blinman”. Exact locality uncertain,

Microscopically the rock is porphyritic with a sub-ophitic texture. The

phenocrysts are sub-calcie augite, biaxial (+ ve) 38/44 degrees, with maxi-

mum observed extinction of 35°. Phenocrysts of olivine are completely

altered to aggregates of magnetite, antigorite and higher birefringent tale

The plagioclase is secondary andesine (Ab,,An,,).

MELAPHYRES

Cl—Amygdoloidal olivine-free melaphyre

No. (9031). This is a dark grey pdrphyritic yesicular rock from locality

77 containing phenocrysts of light brown felspar and fight green chloritic

masses set in a dark fine grained groundmass. Vesicles are filled with deep

brown siderite associated with a little limonite. Other vesicles contain

calctte and quartz. Common features are the lining of vesciles and micaceous

haematite, the occurence of green copper stains and odd grains of pyrite.

In thin section the rock is holocrystalline porphyritic and highly yesi-

cular. The phenocrysts are set in a devitrified groundmass. The plagioclase

gives extinctions up to 29° in the symmetrical zone, indicating labradorite

Ab,,An,,)- However, the majority has maximum extinction of 16°, The

* RJ. in relation to balsam is dificult to determine due to the interference of

alteration products and the obliteration of the basal cleavage. But as. goad

and well defined multiple twinning is present the composition is assumed to

be Ab,,An,,: andesine. eA t

The only ferromagnesian is light green chlorite occurring in large

isotropic basal sections. Siderite is abundant as pleochroit brawn to lighter

shade, Limonite is assuciated and is quite common as a coating over the

siderite. Calcite is intersertal with the groundmass, but is difficult to dis-

tingnish from siderite as the former grades into siderite by simple tron

replacement,

The groundmass is fine grained with an intersertal texture which does

not show any flow structure. The above minetals are represented in addition

to abundant magnetite, haematite and rutile. The late deuteric introductions

are uniaxial (+ ve) glass clear quartz, and low relief biaxial (—ve), 2V’ =

43° anorthoclase, together with minor muscoyite and chlorite, which are

probably a recrystallization of the alteration prodticts.

The amyegdales are all filled with calcite ar pleochroic siderite and associ-

ated red-brown limonite, quartz, felspar and chlorite showing regular zoning,

Successive zones commence with magietite of the groundmass to a light

green isotropic chlorite zone, followed by a haematite-chlorite zone in which

the chlorite is intersertal between the flaky haematite, which in basal sections

185

is translucent red. This is followed by am intergranular sass of potash

felspar and quartz before the final residual cavity is filled by siderite,

No. (9026), from locality 92, is a pronounced variation, A fine grained

amygdaloidal containing a series of long drawn vesicles lined with dark green

silicate and calcite,

In thin section the texture has an intersertal form with glomeropheno-

crysts of felspar alteration products. The former felspar phenocrysts have

been saussuritized, resulting in a fine mass of clear untwinned albite inter-

grown with chlorite. The mass does not show epidote, which has been

recrystallized and remoyed to the general groundmass. The latter shows

saussuritized plagioclase as frayed fragments with very little multiple twin-

ning. Unlike the phenocrysts, plagioclase here includes epidote. Ilmenite

is partially altered to leucoxene. Vesicles are elongated and vein-like, lined

with thick green mattered chlorite in non-pleochroic isotropic sections, inside

hie is quartz, calcite, and haematite with disseminated laths of preen

chlorite. ily f

No. (9014) is a light grey porphyritic rock containing stumpy pink

plagioclase phenocrysts set in a fine groundmass containing little dark

mineral content,

In thin section the felspar has prominent Brayeno and albite twinning;

RI. greater than balsam; biaxial (+-ve), 2V=85°, indicating andesine.

Regeneration of a higher order has given glassy clear varieties of oligoclase.

The groundmass oligoclase with original ferromagnesian represented by

green chlotite and biotite. Interstitial cavities and vesicles are filled with

calcite and micaceous haematite, which is readily detected by its red basal

sections. The late dueteric introduction is quartz and possibly oligoclase

associated with which is accessory apatite.

C2—Olivine-bearing amygdaloidal melaphyres

No. (9027), from locality 94, is a light green amygdaloidal specimen

containing plagioclase phenocrysts and dark green silicate in a finer mass

In thin section felspar and olivine are observed as phenocrysts, the

former is by far the most abundant mineral. In general composition the

felspar ts andesine (Ab,,An,,)-

Olivine forms euhedral phenocrysts which have suffered breakdown into

magnetite and a mass of light green low birefringent antigorite. Red amor-

phous haematite or limonite represent former iddingsite. Uralite is not com-

mon, but where it occurs it is distinguished from the chlorite by its extine-

tion angle of 15°. Introductions along a vein structure have given calcite,

qtiartz and albite-oligoclase.

No, (9024), from locality 85, is a light grey, fine grained basaltic rock

in which the amygdales are partially filled with radiating needles of dark

green epidote, actinolite and chlorite.

No. (9022), from locality 82, is a fairly typical melaphyre in appearance,

having porphyritic plagioclase set in a purplish, fine grained groundmass

spotted with green silicate. Amygdales are filled with calcite,

In thin section plagioclase laths show albite and Braveno twinning, while

some Carlsbad is evident; composition is Ab,,An,,, andesine. Magnetite

and antigorite form psendomorphs after olivine. What appears to have been

red-brown iddingsite has been hydrated to amorphous Jimonite,

The groundmass is holocrystelline intersertal in texture with micro-

crystalline patches. In this the felspar is less basic than the phenocrysts:

Ab,,fn,,, andesine. Chlorite and calcite replace nearly all original ierro-

magnesian. Minor accessories include ilmenite, Ileucoxene, magnetite and

apatite.

186

The vesicles show zonal arrangement in which the inner zone is occupied

by finely divided calcite flakes, followed by radiating vein structure of green

pleochroic chlorite, and non-pleochroic matted chlorite. Sometimes within

this zone there is a very thin calcite, felspar, quartz deuteric ring armoured

by magnetite and haematite.

D—Fine grained non-amygdaloidal melaphyres

This group represents the non-amygdaloidal melaphyres which are

usually dense, dark and fine grained, and often represent the fine grained

equivalents of the preceding groups, such as (9023) corresponding to (9024).

The same outcrop shows an even more pronounced amygdaloidal structure,

Microscopically examined, (9032) has all the indications of being a spilite.

No. (9023) has an intergranular texture with a slight parallel banding

which is much more evident in the hand-specimen, The felspar is in frayed

laths showing vety poor multiple twinning and is albite-oligoclase. The

uralite is in the form of light green actinolite with Z Ae 20°. Chlorite is

not abundant.

No. (9030), from [ocality 78, is similar to (9023) but a little coarser

grained. In this section the texture is intersertal. The plagioclase is albite,

Actinolite is abundant as fibrous and compact laths: Z Ac 15°, biaxial

(—ve), 2V=80°. The remaining minerals are subordinate and include

epidote, chlorite in small laths and fibrous to matted structures. Magnetite

and calcite and clear quartz are of a secondary nature, Scapolite may be

present.

No. (9032), from Jocality 71, ts dark grey, very fine grained cock, in

which vesicles are filled with rhomb-shaped porphyroblasts of siderite.

In thin section the rock is holocrystalline with an intersertal texture of

the three main minerals, plagioclase, chlorite and magnetite. The felspar is

difficult to determine, due to alteration, and very little residual twinning

may be seen. The laths are broken and mottled near extinction: R.I. <b,

thus albite-oligoclase.

Chlorite is much more abundant than first appears, due to its very light

green to colourless appearance. Magnetite occurs in very great quantity,

suggestive of original iron-rich ferromagnesians, Calcite, biotite and rutile

are present. Siderite and calcite rhombs grow in the general rock base and

indicate a certain amount of thermal metamorphism to form these porphyro-

blasts. In addition to this, biotite occurs within their limits, indicating com-

bination of seticite, muscovite, calcite and iron under the thermal conditions.

ASSOCIATED ROCKS

Associated with the basic rocks of Blinman area are several outcrops af

gneiss described by Howchin as gneissic granites, and later as conglomerate

paragneisses by Benson. However, a clue to their origin is seen at locality

157, where a pegmatitic rock has been intruded into a brecciated quartzite

and purple slate. About it is a small iton-rich aureole. This rock, (9019),

is principally microcline perthite, oligoclase, quartz, and a great number of

accessories, including biotite, magnetite, sphene, rutile, zircon, apatite,

haematite and pyrite,

In this section the gneiss at locality 172 is very similar to this in mineral

content, with the exception that it contains more biotite and has suffered

stress during emplacement,

No (9019), from locality 1597, is a coarse grained pink rock consisting

of large crystals of buff to flesh-red felspar, colourless quartz and odd patches

of black micaceous materia].

187

In thin section the rock is holocrystalline, hypidiomorphic granular,

The chief mineral is plagioclase twinned on the albite and combined albite-

pericline laws with maximiim extinction of 6°. RI. > balsam indicates

Ab,,An,,, oligoclase. It is biaxial (+ ve), 2V approaching 90°. It is severely

stressed and shows undulose extinction to a high degree; the twinning planes

are stressed and buckled to such a degree as to sheer along definite planes

as in false cleavage.

Quartz is in anhedral crystals, showing peripheral granulation; its optical

figure varies irom uniaxial to biaxial with small 2V. Microcline perthite

shows exsolution of albite, The relief of this albite is less than that of the

microcline, and the figuse is biaxial (+ ve), 2V =75°, while the microcline

is. biaxial (— ve), 2V = 80°.

No. (9037), from locality 172, is a coarse grained gnessic rock containing

buff to flesh coloured felspar, clear quartz with schistose bands of biotite,

Microscopically the rock is granulose with a suggestion of gneissic

structure, Post-crystallization cataclastic effects have commenced myloniza-

tion along parallel zones of both the felspar and quartz, giving rise to fine

sericite and chlorite about lensed felspar and quartz, Mictocline perthite

occtits as turbid xenoblastic crystals sheared in the peripheral zones and in

general having undulose extinction, low relief, biaxial (—ve) with a large

optical axial angle. Plagioclase is not common; it is slightly turbid, due to

incipient decomposition: R.I.<b, biaxial (+ ve), 2V approaching 90°. And

therefore Ab,,An,,, oligoclase,

Quartz is cloudy due to inclusions, and shows marked peripheral granu-

lation, causing undulose extinction and an optic axial angle up to 20°. The

primary mica is biotite, which is strongly pleochroic: X = light straw yellow,

Y = Z = dark green-brown, It is biaxial (—ve), 2V =10/12 degrees as

in (9019).

The granulation has deyeloped parallel to gneissosity, with the result

that Secondary sericite has developed with the biotite. Accessories include

magnetite, limonite, sphene, chlorite and zircon included in the biotite,

Apart from such pegmatites, there occuts an abundant suite of para-

gneisses which have resulted from the combined action of shearing stress

coupled with the heat of the basic intrusions. This adequately explains the

limited extent of each individual occurrence.

Generally the intrusions are small or were quickly cooled, so that contact

effects on the immediate surrounding rocks are small. However, where a

hornfels would be expected in the surrounding slates, it is repeatedly found

that coarse gneisses have formied in its stead. In the case of locality 7,

gtadations occur from slate to bimica-schist to coarsely foliated biotite-

gneiss in which coarsely saccharoidsl quartz bands nearly a quarter of an

inch thick alternate with micaceous bands.

Associated with gneisses at two localities, 4 and 200, are occurrences

of tale schists, such as B137. In the hand specimen the rock is light-green

to grey and greasy, with the micaceous flakes in schistose arrangement. In

thin section the talc is in colourless flakes and laths with extinctions of 3°,

and is distinguished from muscovite by its lower axial angle. Other minerals

are quite accessory and include amorphous limonitic material, golden-brown

rutile and magnetite, which is arranged in single and double sets of parallel

stringers, showing the presence of former twinning sa commonly seen in

the uralitic amphibole of the area. The present form has possibly resulted

from the pneumatolytic alteration of a dolerite. In hoth cases the Gutcrops

ocecut in the centre of yneissic bodies.

188

ACKNOWLEDGMENT

The writer is indebted to Sir Douglas Mawson recommending this

investigation as a subject for the Honours Degree of the School of Geology,

University of Adelaide.

REFERENCES

Battey, E. B., and Grapnam, G. W. 1909 Albitization of Basic Plagioclase

Felspars. Geol. Mag., June 1909

Benson, W. N. 1909 The Basic Rock of Blinman, South Australia, with Notes

on Associated or Allied Rocks. Trans. Roy. Soc. S. Aust., 33

Dicxrnson, S. B. 1942 The Structural Control of Ore Deposition in some

South Australian Copper Fields. Dept. Mines. Bull. 21

Howcnin, W. 1922 A Geological Traverse of the Flinders Range from the

Parachilna Gorge to the Lake Frome Plains. Trans. Roy. Soc. S$. Aust.,

46, 46-82

Mawson, D. 1926 The Wooltana Basic Igneous Belt. Trans. Roy. Soc.

S. Aust., 50, 192-200

Mawson, D. 1939 The Cambrian Sequence in the Wirrealpa Basin. Trans.

Roy. Soc. S. Aust., 63, 331-347

Mawson, D. 1942 The Structural Character of the Flinders Ranges. Trans.

Roy. Soc. S. Aust., 66, (2), 262-272

Tyrrett, G. W. 1928 The Geology of Arran. Memoirs of the Geological Sur-

vey, Scotland

Witson, A. F. 1948 The Charnockitic and Associated Rocks of North-Western

South Australia. Part II. Dolerites from the Musgrave and Everard

Ranges. Trans. Roy. Soc. S. Aust., 72

THE SOILS, GEOLOGY AND VEGETATION OF NORTH-WESTERN

SOUTH AUSTRALIA

BY R. W. JESSUP

Summary

The area described is approximately that which lies north of the transcontinental railway, west of

Lake Torrens and Eyre, and westward toward the edge of the Nullarbor Plain.

189

THE SOILS, GEOLOGY AND VEGETATION OF

NORTH-WESTERN SOUTH AUSTRALIA

By R. W. Jessup, M.Sc. *

[Read 12 April 1951]

CONTENTS

SuMMARY - - - — a 2 = 4 3 fo

INTRODUCTION - - ~ - - - - - - Ps =

CLIMATE - - - = . 2 ¢ = ~ ne =

CATTLE, SHEEP AND OTHER ANIMALS - “ - - - - z =

Stock numbers - - - - - = =" 7 7 * 7

Rabbits - - “ 2 Ba is fc 6s wee

Native animals and birds - ~ - - pe - - s =

GroLocy AND PHYSIOGRAPHY - - - - - - 7 a6

Precambrian - Cambrian complex a a a

Jurassic - - - - = - “ a ~ - ta

Cretaceous - - - = - a a re < 2 ie

Tertiary climates and their effects on the older geological formations

Physiographic features - iA - 2 i “ & = i

Soil-geology relationships. The surface deposits - - - -

Origin of the soils from geological parent materials illustrated diagram-

matically - - - - = “ Es 7 “ =

Types of billy - - + ee ee ee ee

THE SOILS - - - - ‘ Z 5 a ! - » -

Classification - - - - - + - " = & e

General characteristics - - - ~ - = - + :

The soil families - - - a a - -

1. Arcoona - - - " m a « . & -

2. Coober Pedy ~ «© «© #© 2+ © = a

3. Twins - - - - . - = “ : “ -

4, Wilgena » - -* «= - . = é bd =

5. Bon Bon - - - - « a! . ~ = A

6. Wirraminna - - ~ o = - A. L. “ -

7. Miller’s Creek - - - ~ » - - < -

8 Mt. Eba mi OS wake SS ee SR ny. eee

9, Coondambo - e HF = = We aw z &

10. Red sandhills & ft ew | 9s a ‘=

Erosion - - - = - a a 3 2 wh &

Analytical data - - - - - - = . = - -

* Soil Conservation Officer, Department of Agriculture, South Australia.

Trans. Roy. Soc. S. Aust., 74, (2), Dec. 1951

200

ail

196

Page

THE VEGETATION - = = = = = *© = = 2 # = 2

Classification of the plant communities - sek et me

The palatability of the species - - - - * + = # 3

The plant associations - - - - a - 4 = a 2 232

1, Acacia aneura= A. brachystachya association - - - - -

A. sowdenii-—Kochia sedifolia association ~- - - = -

K. sedifolia association - - - s+ = = = - -

A, linophylla-—A. ramulosa association - . - - - -

Zygochloa paradoxa association - - - - - -

Eremophila freelingii- A. aneura— A. brachystachya association -

A. aneura—A. brachystachya—A. tetragonophylla association -

Kochia planifolia- Bassia spp. association - - - - +

Kochia planifolia association - - - - - - - -

Atriplex vesicaria-—K. planifolia association - - - = -

SPnan fw

— So

. A. vesicaria— Bassia spp. association - - - - -

. A vesicaria~Ixiolaena leptolepis association - - - - -

. A, rhagodioides association - - - - - - - -

14. K, planifolia—A. vesicaria —K., sedifolia association - - -

— ee

ww M&S

The plant communities associated with swamps, watercourses and creeks:

1, Mulga swamps” - - - - - a = z - =

2. Melaleuca spp. swamps - - = - = = = = =

3. Atriplex nummularia swamps - - . A - Bs .

4. Canegrass swamps - - - - - f - =) #¢

. Smaller watercourses and creeks in shrub steppe areas

6. Larger watercourses and creeks in shrub steppe areas -

7. Creeks of the northern tableland country, - - - - = |

Changes which occur in the plant communities with grazing is - 258

The plant communities as grazing units - - - - - - =

Quantitative estimations and mapping of bush density - - - - 265

Discussion = = = 268

APPENDIX A— The ecotypes of saltbush (ériplex vesicaria) - - - - 271

ACKNOWLEDGMENTS - - - - = - PS = “ a ¥

REFERENCES - - - - - - - - - - - - - 272

SUMMARY

The area described is approximately that which lies north of the transconti-

nental railway, west of Lakes Torrens and Eyre, and westward toward the edge

of the Nullarbor Plain.

The average annual rainfall vaties from 43-7”. Prolonged droughts are

common. The introduced and native animal populations are discussed briefly.

The rocks are mostly sedimentaries— Precambrian-Cambrian complex

(largely quartzites), Jurassic sandstones, Cretaceous shales and Pleistocene

aliuvia. Recent wind-blown sands are widespread in the south. Vast plains from

200 to 500 feet aboye sea level dominate the topography.

191

' Silicification of the surface (Cretaceous) deposits occurred during the earlier

and later Pliocene, with a period between during which the resultant soils and the

Cretaceous shales were variously truncated. Further truncation of the Pliocene

soils and the Cretaceous shales occurred in the Pleistocene, resulting in exposure

of underlying Jurassic sandstones in the south, Alluvium was also deposited in

the Pleistocene,

The surface sands were stripped off the Pliocene soils in the arid Recent,

and sands formed from the exposed Jurassic sandstones were resorted. Sand-

hills formed upon soils derived from Pleistocene alluvia and gypsum and sodium

chloride accumulated in the soils. Pedological evidence indicates four moisture

regimes during the Recent.

The type of soil formed from the Cretaceous shales depends upon the extent

of truncation of the profiles. Over the tableland areas (preserved Pliocene topo-

graphy) the soil is a deep clay with a surface mantle of billy gibbers derived from

break-up of the siliceous B horizon of the Pliocene soil. Crabholes are developed

and the soil contains heavy gypsum but no lime.

Shallower clay soils have resulted from either Pleistocene truncation of the

deep clays or were formed during the second period of silicification from shale

exposed hy the erosion which occtitred in the inter-silicification period. Crab-

holes may be present in these shallow clays and the soil contains heavy gypsutn

and a trace of lime. Billy gibbers again occur on the surface,

The Pliocene soils were completely removed from large areas in the Pleisto-

cene to expose bleached shale upon which a very shallow soil has subsequently

formed, Pleistocene erosion not only resulted in loss of part or all of the Plio-

cene soil but often caused complete or almost complete truncation of the Creta-

ceous shale itself. A very shallow soil overlying limestone hardpan has sub-

sequently formed where a shallow layer of shale remained.

Two different sandy and calcareous soils developed where the Cretaceous

beds were completely eroded away and the underlying sandstone was exposed.

The shallow sands constitute Bon Bon soil and the deeper sands constitute Wirra-

minna soil, Coondambo and Mount Eba soils have developed upon Pleistocene

alluvium. They both consist of shallow sand over red clay and contain lime and

gypsum.

The billy gibbers vary considerably im their structure. Four different types

are described, Accelerated erosion has been generally insignificant.

The vegetation consists mainly of chenopodiaceous shrub steppe communities

on the heavier textured soils, and acacia woodlands on sandy soils. Two or

more associations are commonly grouped together to form association com-

plexes.

The dominant shrubs (12’-36” high) of the shrub-steppe communities vary

in their lateral spacing but are rarely touching. The woodlands, which are fairly

open, consist of trees 16 to 24 feet high, Beneath the trees there may be an

understorey of shrubs with perennial grasses dominating the ground layer, or

the shrubs may be absent, depending upon the depth of sand in the soil, Severe

tree death has occurred im the woodlands and little regeneration is taking place.

The shrub steppe areas may be uniformly bushed but in crabhale country growth

is restricted to the depressions, the shelves being too arid and too saline. During

drought times the ground between the shrubs and trees is bare,

192

The trees and shrubs provide a drought reserve of feed, but in prolonged

droughts the trees are more valuable because the shrubs become defoliated. Over-

grazing depletes the palatable species and causes thinning of the dominant shrubs

and increase in the amount of bindyi (Bassia spp.). The high protein content

of the chenopods is largely responsible for the production of large-framed sheep

and high wool yields,

Detailed floristic lists of the species occurring in the associations are given

and their relative palatabilities are rated.

The delineation of the boundaries of the different vegetation associations

alone does not give an adequate picture of the grazing potential, as it is also

necessary to indicate the state of preservation of the country. Five stages of

degeneration of bush dominant country are recognised and defined quantitatively,

and a portion of the North-West has been mapped on this basis. Two plans haye

been prepared, one showing the estimated original bush densities prior to stocking

and another showing the present densities. From these two plans the amount of

bush lost through grazing has been calculated,

en — ee nny

‘

i FOTH wALre

Fig. 1

INTRODUCTION

in 1943 the writer was appointed to the Soil Conservation Branch of the

Department of Agriculture to investigate matters pertaining to soil eresion

in the arid pastoral areas of South Australia and to provide data that might

guide the Government and the pastoralists in the framing of policy with re-

spect to these areas. The work reported herein is a comprehensive review

of conditions in the north-western portion of the State, the boundaries of the

area being shown-in Figure 1. Field investigations were carried out during

the period 1945-1950. Prior to the commencement of this work very little

precise knowledge of the soils, vegetation and geology of this region was

193

mere BF tetinme

preneneese*¥,

Aeeern peiertaaen

Pere riytis deme ratgas

Mace gttriane

—

Aa, id

rks aN xt

a Sree hotur

‘ i tie 8

iat felt abd a

. a een haa & va Sy | Wl i

7 ee Toreacla eeisg / -. hee: loxtart

bi PZ 7 7 he mali!

Feretzetae 0

(onenie =_—— hte ye Seeeese es ae ne

Aivtovpegspetseet 2

C "aes ‘= Ptah ie Pe | D

Seng abet ~<a]

att)

Rastiingia rigtaa

Marariytss Severely

fimel of 4

BIY FO MSETRIBUTION OF SPECIES

AND ROUTES GF EXPLORERS Cratystyis Sonuceshala

pier bene araesk

oF Ie heitas

‘iALut Calliden gfescrn Pa

WE itecig Scar see

Stems (O38 - “ese

Seeant fees seer

" Madtdage fasa-/ase

Merkurtos COsa- ses"

sare: Lewee vere

ceeeee Steer ee nd ee

Fuintatli fratyets shown a-

Fig. 2

Showing routes of explorers, rainfall isohyets and distribution of certain plants.

194

available. A paper dealing with the geography of the area is being published

in the journal of the Royal Geographical Society of South Australia.

The southern portion of the North-West with an area of 23,000 square

miles is used for the grazing of sheep, while the northern portion (28,000

square miles) carries cattle. Throughout these areas grazing is dependent

principally upon native plant species and considerable damage to the peren-

nial plant cover has resulted through overgrazing and other factors.

Fig, 3

Graph of annual rainfall of South Gap station for the years 1882 to 1944,

CLIMATE

The average annual rainfall varies from about 44” in the Lake Eyre

region to 7” in the south (figure 2). However, the average figure has little

significance, Thus South Gap Station, which has an average of 652 points per

annum for the period 1882 to 1944, has varied in yearly rainfall from a mini-

mum of 168 points in 1902 to a maximum of 1,730 points in 1928. The fluc-

tuations in annual rainfall for South Gap are shown in figure 3.

There is no marked seasonal rainfall as the area lies in a zone where the

limits of the southern winter rainfall and the northern monsoonal summer

rainfall systems overlap (Table I).

Taste I

Average monthly rainfalls (in points)

No, of

Yeare Jan, Feb, Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Year

Oodnadatta ... 51 71 63 43 21 30 63 20 19 26 45 33 42 476

Tarcoola aie 28 34 71 46 36 65 82 53 71 56 71 53 62 700

The southern portion of the North-West as illustrated by the recordings

for Tarcoola (Table 11), has its greatest number of rainy days during the

winter months May, June, July and August and the summer months Novem-

ber and December. As shown by the Oodnadatta record, in the north the

greatest number of

195

rainy days occurs in the summer months (October,

‘November, December and February) and the winter months June, July and

August.

Tasie II

Average number of rainy days

No. af

Years Jam Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dee,

Tarcoola we 8 23 #4@tlo 21 33 34 44 51 45 18 30 34 3.8

Oodnadatta 4 2.5 5.3 2.3 1.3 1,5 30 28 4,0 2.3 2.8 3.5 4.3

In the southern portion of the North-West rains of greatest intensity fall

during the summer months (Table II). Further north the intensity of the

winter rains is also fairly high. The records for Oodnadatta are only avail-

able for a period of four years, but they might be expected to give some indi-

cation of conditions.

No, of

Years Jan.

Oodnadatta 4 28

Tarcoola we «8 15

Taste IIT

Average rainfall per rainy day

Feb. Mar, Apr. May June July Aug: Sept, Oct. Nov. Dee

12 19 16 20 21 7 5 li 16 10 10

23 22 10 19 19 «19 16 al 24 16 16

Jessup: (1948) has pointed out that severe wind or hail storms occa-

sionally sweep through narrow strips of pastoral country causing much

damage to the vegetation. This is illustrated in Plate XIII, Figures 1 and 2.

Figures indicating the temperature regime are shown in Tables IV, V.

VI and VII.

Taste IV

Mean monthly temperatures of Tarcoola and Oodnadatta

No. of

Years Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dee.

Tarcoola 18 «78.7 78.5 74.4 64.9 584 S519 519 54.3 59.9 66.1 717 76.0

Qodnadatta 55 83.4 82.9 79.4 701 60.7 55.1 S4.3 584 666 711 783 845

TABLE V

Number of days for each month when the maximum temperature is

100° F. or more

No. of

Years Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct, Nov. Dee

Turcoola ww 8 95 6.8 2,1 x] 0 0 0 0 ti 4 3.9 6.3

Oodnadatta ... 4 163 11.0 LR o 0 0 0 0 2 20 53 85

Tastr VI

Number of days when the minimum temperature is 40° F. or less

No. of

Years Jan Feb. Mar, Apr. May June July Aug. Sept, Oct, Nov. Dec

Tarcoola g 0 0 0 0 51 119 13399 45 9 0 0

Ocdnadatta 4 0 0 0 a 3 43° 50 10 0 0 Q ¢

Taste VII

William Creek—

Minimum ....

Normal mean maximum and normal mean minimum temperatures for

each month for William Creek and Tarcoola

Tarcoola—

Maximum

Yrs. Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Yre-

Maximum .... wai «(89 96.3 964 89,7 BO.3 71.4 65.2 64.5 681 76.3 84.4 90.0 95.3 81.6

na | 89 68.8 69.6 63.5 55.0 474 43.2 40.7 43.5 49.0 56.3 62.7 67.4 55.6

wee we 48 93.8 941 89,5 79.1 71.8 64.6 64.5 67.9 74.9 81.8 87.6 91.8 801

we = 18 635 63,0 59.3 50.7 45,0 39.5 37.9 40.6 45.0 50.5 S5.8 60.1 50,9

196

Frosts are of extremely rare occurrence at Oodnadatta, but for the six

years 1943-1948 inclusive, the following are the total days for each month

when the minimum temperature has been 32° or under at Tarcoola—May

5 days, June 23, July 26, August 9 and September 3. The other months are

frost-free. ;

Although Yudnapinna Station lies slightly to the south of the area dealt

with in this paper, the figures in Table VIII, which shows the average

greatest daily range of temperatures in degrees Fahrenheit for the petiod

1941-1948, will be representative of the North-West generally, The greatest

daily range occurs during the summer months.

Taste VIIT

Jan, Feb. Mar. Apr. May June July Aug. Sept, Oct, Nov. Dec.

41.0 379 369 35.2 339 329 34.2 47.1 40,6 41.4 41.5 42.3

Evaporation is high and relative humidity is low, particularly during the

stimmer (Table (IX),

TaBLe IX

No,

Yudnapinna— Yrs, Jan, Feb, Mar. Apr. May Juno July Aug. Sep. Oct. Nor. Der.

Evaporation in *. S$ 146 12.2 106 GE 43 28 $0 41 #65 B81 114 A154

Tarcoola—

Saturation deficit

Mean, 9.00 am..,, 15 “513.0 52300 441. 170-167 096 «100 248 «239 350) 471 LB

Mean telative hu-

midity (saturation ’

= 100) saad «a OF 32 33 36 43 51 60 55 48 38 31 30. 30

Prevailing winds are from the south-east, although the direction of the

winds tends to be variable during the winter months, On account of the

tendency of sheep to gtaze into the wind, the prevailing south-easterly wind

results in concentrated grazing in the south-eastern corners of paddocks.

The direction of the prevailing winds must have changed since the time the

east-west trending sandhills were built up, since Bagnold (1941) has shown

that in seif dunes the long axis of the dune is aligned parallel to the direc-

tion of the prevailing wind. Furthermore, lunettes, which are aeolian accu-

mulations, are found along the eastern margins of the salt lakes in the North-

West. They could only form in this position under the influence of prevail-

ing westerly winds. These east-west trending dunes and lunettes are discussed in

the section dealing with geology.

SHEEP, CATTLE AND OTHER ANIMALS

The sheep carried in the pasteral country are large-framed, p'ain-

bodied Merinos (Plate XIII, Figure 3). Fleece weight per head of sheep

naturally varies considerably according to the seasons, but a cut of 12 pounds

for grown ewes and 13 pounds for grown wethers is an average figure, The

wool has a count of 60-64's,

Blowflies are the chief pest of the sheep industry, and to reduce the m-

cidence of fly strike the sheep are generally crutched once a year, and the

Mules operation is becoming more widely used of recent years. Recently

lice have appeared in the sheep of the North-West, and several stations are

dipping to control it. Tick are absent, Wild dogs are now a serious pest

only on the most northerly of the sheep stations, that is, those adjacent to

the cattle country. One dingo can, however, kill a large number of sheep in

197

a. short time, and their presence in the unfenced cattle country necessitates

any sheep carried there being shepherded. Shearing is carried out during

either of two periods—February to March or August to September.

The cattle carried on the stations are Shorthorns or Herefords (Plate XIII,

Figure 4).

| Stock NUMBERS

; ‘The numbers of cattle and sheep carried fluctuate according to the

seasons, rising in good years and falling during drought times. Sheep num-

bers for the whole of the sheep country covered in this survey have fluc-

tuated from a maximum of 410,000 in 1939 to 145,000 in 1946 (Figure 4),

while cattle have varied from 13,000 in 1940 to 30,000 in 1947 in the northern

cattle country. In addition to the cattle, a few sheep are shepherded in the

cattle country. Their numbers have varied from 2,500 in 1935 to 8,000 in

1948.

420

4ca

380

D 360

Baa

< 320

FA 3200

3 280

“e260

1 240

ut 220

ZT 500

17]

180

Iso

1935 36 37 38 39 40 4: 42 43 44 45 46 47 46

YEAR

Fig. 4

Owing to this variation in cattle and sheep numbers according to sea-

sonal conditions, the arid pastoral areas have no fixed carrying capacity per

square mile of country. Only the drought-resistant perennial vegetation re-

mains under drought conditions, and it may even be difficult to hold a flack

of ewes from which to breed when the seasons improve. On the other hand,

in good years there is such a wealth of herbage and grass that the perennial

vegetation is scarcely grazed and sheep numbers can be greatly increased

without harm to the permanent plant cover. The danger is, of course, that at

any time a protracted dry period may set in. If sheep numbers are not re-

duced at the onset of the drought, but are held in the hope that rain will soon

fall, not only is the country damaged but. eventually the stock either have

to be sold at a very low price or it may be impossible to market them, de-

pending upon conditions in the higher rainfall country to the south. Conse-

quently pastoralists now generally build up their flocks to numbers that can

be carried in an “average” season.

198

As indicated above, pastoral country has no fixed carrying capacity and

the fluctuations from year to year in stock numbers are great. In spite of

this it is of interest to know what stock the North-West as a whole is carry-

ing to the square mile.

It is standard practice to work out the average stocking rate per square

mile of country by dividing the average number of sheep carried by the area

of the country in square miles. If the following stations are considered on

this basis, namely, Mulgathing, Malbooma, Wilgena, Bulgunnia, McDouall

Peak, Ingomar, Mount Eba, Bon Bon, Mt. Vivian, Miller’s Creek, Coon-

dambo, Wirraminna, Parakylia and Roxby Downs, with a total area of

14,500 square miles and carrying an average of 204,000 sheep for the period

1935-43, the average carrying capacity pér square mile is 14°3 sheep. To

arrive at this figure 200 sqnare miles have been deducted from the tota] area

of the stations, since this represents the area of salt lakes,

However, this average figure of 14-3 sheep per square mile for the 14

stations as a whole is misleading, because most of them have some areas

which are ungrazed or grazed only very lightly. Thus a total of 2,100 square

miles is made up of paddocks which do not contain any stock water. The

greater portion of this area is not grazed, while other of the paddocks carry

stack during very good seasons only, that is, when there is sufficient succu-

lent feed to enable the sheep to exist without water,

In addition to this unwatered country we have to consider that sheep

do not graze beyond a four-mile radius of water except after very good rains,

when surface water or succulent feed is available. Even when these fayour-

able conditions prevail not all the shecp in the paddock will be grazing beyond

four miles of the water. The areas which carry the stock most of the time,

and patticularly during the critical drought periods, lie, therefore, within four

miles of permanent or semi-permanent water.

If the positions of the watering points in each paddock of the 14 stations

mentioned above ate considered, we find that 8,650 square miles are within four

miles of water. This area is carrying stock at the rate of 23-6 sheep to the

square mile, and the writer considers that this figure is a more accurate in-

dicatiorn of the average stocking rate of the portions of the North-West

which actually support sheep. It does not necessarily imply that the stocking

is excessive, Until more research stations similar to Yudnapinna (Wood-

roate, 1941) but wsing larger paddocks, are located in the different vegeta-

tion types of the North-West, no significant figures for carrying capacity will

be available, nor will we know what the area of paddocks should be to

balance efficient utilization of forage against economic returns.

At present many paddocks are far too big. Even when the small “hold-

ing” paddocks around woolsheds are included the total number of paddocks

in the 14 stations is only 442, giving an average size of about 32 square miles.

The total number of waters on these stations is 360. This represents

the sum of all watering points at bores, wells and dams as well as tanks along

pipelines, On an average, therefore, there is a watering point for every 39°7

square miles of country. To avoid damage to the bush cover through ex-

cessive tramping, it is probable that no more than about 600 sheep should

regularly water at any one point.

Ragspits

Although stock are the principal cause of the degeneration that has

occurred in the pastoral country, nevertheless rabbits have played a very

considerable part.

199

Rabbit numbers fluctuate enormously according to the seasons, Good

years result in them breeding up to such an extent that they soon reach

plague numbers and the damage they do is everywhere evident. With the

onset of hot, dry weather and drying-off of herbage and grass they die quickly

and in such numbers that the air in places becomes polluted with the smell

of rotting carcases. After a while it is possible to drive hundreds of miles

and scarcely see any rabbits at all. While the damage done by a big rabbit

population is easily seen, the difficulty is to assess the damage caused by a

meditim population.

Duting 1948 rabbits reached plague numbers in the North-West, but

no areas of saltbush or bluebush were actually destroyed by theni. On the

other hand, many of the bushes suffered some damage, as it was usttal to

find a litter of twigs on the ground around the base of the bushes. Rabbits,

therefore, cannot be held directly responsible for death of saltbush and blue-

bush except under rare circumstances (see Plate XIV, Figure 1). In fact, as

Ratcliffe (1936) has observed, the most vigorous bushes are often found in

and around rabbit warrens because of the extra moisture they receive. Rab-

bits have an important indirect effect upon the bush cover, Plagues only

occur in good yeats when there is an abundance of herbage and grass, but

enormous amounts of fetd which would otherwise have been available to the

stock when conditions become dry are consumed, As a result, stack are

forced to graze bush earlier than they would if rabbits had been absent.

As soon as the feed dries off, rabbits are forced to seek moisture and

large numbers commence to die. At this stage the worst period of destruction

begins. Young shrubs and trees are ringbarked and killed to secure mois-

ture. Even mature shrubs and trees with leaning trunks or intricate branches

are climbed and the young shoots are barked (Plate XIV, Figure 2), During

1948, when the plague was at its worst, rabbits could be seen jin shrubs

throughout the North-West. Their activities could often be traced to a

height of 15 feet above the ground in the easily-climbed dead-finish (Acacia

tefragonophyllc) and many rabbits died as a result of becoming caught among

the branches.

Most shrub species suffered some damage but greatest devastation oc-

curred among prickly Acacia {Acacia victoriae), dead-finish (4. tetragona-

Phylla}, mulgas (4. aneura and .4, brachystachya) and species of Cassia {Plate

XIV, Figure 3). A. wvictoriae, being a vapid grower, is not in danger of being ex-

terminated in spite of the fact that most of the young plants and a great many

of the mature ones were destroyed by rabbits in the 1948 plague. On the

other hand, rabbits will eventually eliminate slow-growing species such as

mulgas and myall. Not all the seedings of these trees were destroyed it

1948, but most of those that survived lost a portion of the bark from their

stems. Unless they mature before the next plague (and this is most un-

likely) the seedlings that survived will probably be ringbarked.

The numbers of warrens and consequently of rabbits varies according ta

the type of country. Warrens are rarely found in the clay soils of the Arcoona,

Coober Pedy, Mt. Eba or Coondambo types, but are very common in Twins

soil and sandy and calcareous soil areas. The sandy soils are those that stap-

port trees and the greatest variety of shrubs, and it is unfortunate that the

rabbit population is highest in these areas where the perennial vegetation is

most susceptible to damage.

It is difficult to control and impossible to eliminate rabbits from pastoral

areas by any known techuique because of the large areas involved and com-

paratively few personnel,

200

Native ANIMALS AND Braps

The essential difference in grazing habit between the native animals and

birds, and sheep and cattle, is that the former are migratory while the latter

are confined to specific areas. Kangaroos (Macropus rufus) are the most

numerous of the native species and have the greatest effect on the pastures,

Duting droughts they congregate wherever localized thunderstotms may have

resulted in a growth of herbage and grass. At other times they are most

numerous in paddocks which are not carrying stock, and as a result they de-

crease the benefits obtained by “spelling” country. While kangaroos are

destroyed in large numbers it is probable that they have increased since white

settlement owing to the improved water supply.

Birds like the emu (Dromaius novae-hollandiae) which occurs throughout

the area, and the native turkey (Eupodotis australis) which ts only seen in

good seasons, ate not sufficiently numerous to have any significant effect

upon the pastures. However, galahs (Cacatua roseicapilla), which occur in

large numbers, undoubtedly consume large quantities of seed.

Fossil evidence of the former distribution of wombats (Lafiorhinus lati

frons) and mallee fowls (Leipoa ocellata) is found in portions of the North-

West, Recession of these species probably occurred in the arid Recent,

Mounds (nests) of the mallee fowl occur in dense mulga country in the

southern portions of Mt, Vivian and Bon Bon Stations. This was the most

northerly occurrence of the species in the area covered in this survey. Old

burrows made by wombats are found in calcareous soils as far north as Com-

monwealth Hill Station.

GEQLOGY AND PHYSIOGRAPHY

Considering north-western South Australia as a whole, the outstanding

feature of the geology is the presence of predominantly Hat-lying sedimentary

rocks, consisting of Precambrian-Cambrian complex, Jurassic and Cretaceous

sediments and Pleistocene alluvia. Recent wind-blown sands are a wide-

spread feature especially of the southern portion. Over these vast plains

sock outeraps are uncommon, the surface generally being covered with Recent

sands, transported material, or soils derived from the underlying strata.

PRECAMBRIAN-CAMBRIAN COMPLEX

West of the Lake Torrens depression there is a widespread occurrence

‘of almost horizontally-bedded sedimentary rock which have been variously

referred to the Proterozoic (Adelaide Series), Cambrian, or the Ordovician

systems. The sediments are largely quartzites, but include dolomites, con-

glomerates and green and brown shales. So far they have proyed unios-

siliferous.

On lithological grounds the beds were originally assigned ta the Ordo-

vician. Subsequently there has been an increasing tendency to link the indi-

vidual formations with various horizons of the vast sedimentary sequence

{Adelaide Series and Cambrian) of the Flinders geosyncline lying to the east

{David 1932; Segnit 1939; Dickinson 1942). Mawson (1947) has suggested

that these formations may be equivalents of the basal portion of the Adelaide

Series and agrees with Sprigg (personal communication) that some horizons

may include the basal Cambrian quartzite. In early Cambrian times the sea

is known to have transgressed the ancient land massif in the Yorke Peninsula

locality and from this it may be anticipated that a similary overlapping would

alse occur further north.

201

According to Jack (1930), there are three main horizons in the tablelands

west of Lake Torrens, The deepest members exposed are shales. Over these

were deposited sandstones which have subsquently been partly altered to

quartzites, while the uppermost formation is a limestone of sub-crystalline stric-

ture. Erosion has completely. removed the limestone and exposed the more

tesistant quartzite in the higher tableland areas. Upon these formations,

according to Jack, a much younger one, the Eyrian, has been laid down, the

bulk consisting of whitish and mauve clays.

Segnit (1939) gives the following sequence and age of beds:

diiricrust

white and mauve clay . .

with boulders and Lower Tertiary (Eyrian)

sandstone

white clay with boulders Lower Cretaceous

sandstone Jurassic?

limestone

quartzite-sandstone i 5

Cambrian-Precambrian complex

shale

while Dickinson (1942) gives the following:

duricrust Tertiary

white pipeclay tentatively Cretaceous

sandstone

dolomitic limestone

sandstone Cambrian-Precambrian. complex

shale

The writer has observed that west of the tableland country some of the

bores and wells have penetrated quartzites below the Jurassic sands, These

quartzites are encountered as far west as Bon Bon Station and there are small

outcrops in the southern portion of adjacent Wilgena Station. The western

boundary of Bon Bon is the western limit, and the east-west railway line west of

Kingoonya the northern limit of the quartzites.

In addition to this large area of Precambrian-Cambrian rocks west of

Lake Torrens, there are outcrops of granites and metamorphosed rocks of

Precambrian age in the Kingoonya-Tarcoola locality and extending north-

watds to Commonwealth Hill Station. The felspar in the old granite or

gneissic granite is weathered and kaolinized as a result of the high rainfall of the

Pliocene. In addition to the kaolinization of the felspar, billy % pebbles

©) Billy is the term given to the siliceous product resulting from solution and sub-

sequent deposition of silica as distinct from laterite in which the accumulated material

consists of oxides of iron and aluminium,

202

{remnants of the siliceous B horizon of a Pliocene soil profile) occur on the

granites, indicating their pre-Pliocene age. These older rocks haye been in-

vaded by a younger granite which is less weathered (Plate XIV, Figure 4), South

of Oodnadatta, in the Denison Range, rocks of Precambrian age form a north-

south mountain range which rises abruptly from the plain on its eastern side

{Plate XV, Figure 1).

JuRAssIc

Lying to the west and north of the Precambrian-Cambrian area of the

Lake Torrens region and probably overlapping it as Segnit (1939) has indi-

cated are beds of the Great Artesian Basin of Jurassic age. The Jurassics

were the first deposits ta be laid down over the ancient land surface and are

the waterbearing beds of the artesian basin. They are essentially fresh-water

deposits, the area then being a vast inland lake (Howchin 1929). The rocks

are sandstones, sands, sandy clays and clays of various colours (white, brown,

pink, green and yellow}. Many of the bore logs show that the basal beds were

grits, sandy gravel or waterworn quartz stones, Bores on Commonwealth

Hill and Mulgathing (the most westerly stations} penetrate much coarser

beds than bores further east such as in the Mt. Eba region, indicating that the

westerly stations must be near the old Jurassic shore-line.

Rock outcrops of Jurassic age are very rare, the sandstones being usually

covered by sandy soils derived from them or by Cretaceous beds. The only

outcrops are very small and are found towards the southern limit of the

Jurassic deposits, on Bon Bon Station (in the Gosse Range area), between

Lake Labyrinth and Lake Harris on Wilgena Station and along the east-

west railway line on Coondambo Station. The outcropping sandstones are

very coatse-grained and their exposed surfaces have been silicified: West of

Witraminna Station then, the east-west railway line comcides approximately

with the southern boundary of the Jurassic sea.

CRETACEOUS

During Cretaceous times the area in which Jurassic sediments were de-

posited and the Precatmbrian-Cambrian area west of Lake Torrens were in-

vaded by the sea. A blue shale was deposited and for a time conditions were

so cold that glacier ice was present and erratics of quartzite from the Pre-

cambrian-Cambrian and felspar porphyry, gneissic granite and granite from

the Gawler Range-Tarcoola area were deposited (Jack 1939).

The upper layers of the blue shales were bleached to a white colour under

the influence ef the Pliocene climate and were also, in parts, silicified to form

jasper. Precious opal is found in the bleached Cretaceous shale at Coober

Pedy and Andamooka (Plate XV, Figure 2),

West of Wirraminna the east-west railway line roughly corresponds ta

the southern limit of the Cretaceous shale. In this area the shallow Cre-

taceous deposits have largely been eroded away or weathered to a clay soil

which overlies the Jurassic sands. The most southerly outliers of Cretaceous

age on Wirramitna Station (isolated flat-topped hills around the shores af

Lake Hart) show a depth of 30 feet of bleached shale overlying the Precam-

brian-Cambrian rocks. East of Wirramanna, however, the Cretaceous shale

extended further south. In fact, while the Cretaceous beds themselves have

been weathered away, soils derived from Cretaceous shaleS occur in situ

along Spencer Gulf in the vicinity of Port Augusta and Whyalla.

203

TERTIARY CLIMATES AND THEIR EFFECTS ON THE OLDER

GEOLOGICAL FoRMATIONS

The Pliocene is accepted by Whitehouse (1940) as being a period of high

rainfall and warm temperatures. Steady uniform rains prevailed for the

earlier and later portions with a period between of seasonal rains. During the

periods of steady uniform rains, laterites and allied soils formed throughout

much of Australia. However, there is evidence in the North-West which sug-

gests that there must have been a considerable time-lapse between the two

periods of silicification “? because a portion of the inter-silicification period

must have been arid. Thus some of the billy gibbers ©) are a conglomerate

type and consist of waterworn pebbles and small stones resulting from break-

up of the siliceous B horizon formed during the first period of silification

subsequently cemented together by silica during the second period. The in-

teresting point is that the pebbles and stones within the billy gibbers have

red-brown ironstained surfaces similar to the gibbers themselves.

On Billa Kalina Station and north of Coward Springs there is further

evidence to support the theory that there were two periods of silicification

separated by a drier interval. Here non-fossiliferous siliceous limestones

overlie bleached zone material, Billy gibbers resulting from break-up of the

siliceous B horizon formed during the second period of silicification are scat-

tered over the surface of the limestone which has been silicified in its upper

layers by general infiltration of silica and by the formation of seams of quartz

erystals through the limestone. At Moodlampnie Hill (Plate XV, Figure 3}

on Miller's Creek Station, the limestones are about 20’ in thickness, while

north of Coward Springs they are up to 40° in thickness,

It is evident from the present physiography of the country that by the

Pliocene the old land surface was eroded down to a peneplain. The domi-

nant topographical features are the more or less presetved tableland areas

(Pliocene land surface) and the flat-topped residual hills at a similar height

above sea level that are scattered through what is now lower country. Under

the influence of Pliocene rainfall, temperature and physiography, silicification

of the surface (Cretaceous) deposits occurred in the earlier Pliocene, as fol-

lows;

surface sands

Cretaceous

blue shale iron enriched zone (red clay soils)

bleached zone

siliceous. B horizon

bleached zone

Cretaceous blue shale

As no term has previously existed in soil literature the term silicification has

been piven to the process which results in the formation of profiles similar to those

produced by laterization but in which a siliceous (billy) illuvial horizon is formed instead

of a ferruginous one. Another essential. difference between the profiles produced by

silicification and those formed by laterization is that in the former there is no mottled

) Gibbers is the term applied to the larger rock fragments which occur on the

surface of the soil over large areas of inland Australia,

As a result of the change in'the Pliocene from steady uniform raing to

seasonal rains, the peneplain was dissected to varying extents. Over por-

tions of the country it remained fairly well preserved, although some of the

surface soi] was temoved, and break-tip of the siliceous B horizon was

initiated. Elsewhere the soil profile was completely removed and also same

of the underlying Cretaceous shale, Then later in the Pliocene (if we accept

the theory that both periods of silicification are of this age), uniform steady

tains tesulted in the second period of silicification. The result is that the

Pliocene fossil soils occur at varying levels. There is no evidence that lower-

ing of the water table has been a factor in producing soils at the different

levels.

With the onset of a new cycle of erosion in post-Pliocene times, the

peneplain residuals from the first Pliocene silicification period were again dis-

sected to varying extents sometimes with complete removal of the soil and

elsewhere by removal of the surface soil only. Break-up of the siliceous B

horizon contmued. The soils formed during the second period of silicification

were sitnilarly truncated and there were large areas from which the Phocene

soil was completely stripped, exposing the underlying bleached shale. To-

wards the southern limits of the Cretaceous deposits, that is, where they were

thin, the shale itself was removed and the underlying Jurassic sands and

sandstones exposed. Such was the fate of the Cretaceous sediments.

Much of this erosion probably occurred in the pluvial Pleistocene and

at the same time alluvial material was deposited. The most interesting of these

alluvial deposits is found in the Mt. Eba depression and in the watercourses

jeeding into it. This alluvium for cather the soil subsequently formed from

it) is described under the Mt, Eba soil {see soil section), Other areas of

Pleistocene alluvia are found principally around the margins of salt lakes

(see Coondambo soil).

To the south of the tablelands is a system of salt “lakes” of Pletstocene

origin (Lakes Hart, Hanson, Island Lagoon, Gairdner, Harris, Windabout,

and Pernatty Lagoon), During times of exceptionally heavy rains these

“lakes” receive run-off water irom the tableland country and may then con-

tain a few inches of water over portions of their surface (Plate XV, Figure 4).

This water is driven from shore to shore depending upon the direction and

persistence of the winds, but is rapidly evaporated to leave behind the salt

which it contained in solution.

Beneath the salt crust which varies in thickness from 3 to 3” is a thin

deposit (4” thick) of red slushy sand, with dark ted-brown clay containing

gypsum crystals below. The clay continues to a depth of about 18”, Be-

low this ts a layer about 1 ft, in thickness of dark-brown sandy clay contain-

ing black inclusions of ferrous iron. These deposits are distinctly laminated.

Below these alluvial horizons is red slushy sandy clay underlain by the sandy

floor of the lake.

Structures allied te lunettes consisting of powdery gypsum and some

grey siliceous sand are found along the eastern margins of the salt lakes, In

typical lunettes the steeper slope is towards the lake (Stephens and Crocker

1946), but the lunettes associated with “lakes” in the North-West have the

steeper slope on the side of the dune away from the lake. This is probably

due to the jack of stabilization of the hinette dune by vegetation. These

gypseous deposits must have been built up when conditions were somewhat

moister than they are today, that is, before the formation of the salt crwusts.

Under present rainfall sodium chloride accumulates to form a crust over the

lakes,

205

‘When the Pliocene land surface was eroded, isolated flat-topped hills

composed of bleached Cretaceous shale remained scattered through the lower

country (Plate XVI, Figure 1). These features were preserved as a result of

their thicker billy cappings. Their flat tops are covered with billy boulders

and their uniformly sloping sides ate partly covered with billy scree. The

hills, therefore, vary in colour when seen from a distance. If the slopes are

billy-covered the hills appear red-brown while those in which bleached shale

is exposed are white (Plate XVI, Figure 2). A shallow depth of red clay (part

of the Pliocene soil profile) may remain on top of these residuals.

The exact depth to which the blue shale was bleached under the influence

of the Pliocene climate is not known. Biue shale is never exposed in any

of the residual hills. Opal diggings at Coober Pedy (up to a maximum depth

of 90°) are located principally around the lower slopes of residuaf hills and

penttrate bleached zone material throughout.. Logs of bores on Miller's

Creek Station indicate about 90’ of bleached shale (white above but becom-

ing brawn with depth) overlying blue shale. These bores are located in

country from which considerable depths of bleached shale have been eroded,

From the information available, then, bleaching must have taken place to the

unusual depth of at least 120.

Apart from slight iron-stainings (yellow, red or brown) on the surface

of the weathered bleached shale fragments, indications of iron such as mott-

ling are absent. The kaolinized fragments are themselves white and smooth-

textured. Lateritic ironstone and gravel do not occur in the North-West,

While the billy on the surface of the tableland is in the form of polished

gibbers, blocks of billy up to two feet in thickness and several feet across

are found on the tops of the residual hills (Plate XVI, Figure 3). Most of the

billy (the polished gibbers especially) has an iron-stained surface, the colour

varying from red-brown to black, Qn the tableland surface, gibbers which

have been iron-stained right through ate occasionally found. These iron-

impregnated stones usually occur in patches. On Miller's Creek Station

funnel-shaped pieces of billy are common, each gibber having a curved base

coming up to a conical peak, with a circular hole through the peak, Some

of the circular cavities contain yellow ochte (limonite),

While much of the siliceous B horizon was broken up as a result of

truncation of the overlying soil, over the comparatively well-preserved Plio-

cene land surface of the non-dissected tableland areas break-up of the B

horizon must have ptoceeded below the soil surface, because the siliceous

horizon formed within the bleached zone. The mantle of gibbers on the sut-

face is the result of movement of the clay through alternate wetting and dry-

ing which causes the stones to be gradually moved upwards to the soil sur-

face. ;

The surface sands formed as a result of the Pliocene silicifications wete

largely stripped off the old land surface during the arid Recent and deposited

im the surrounding lower country. The sand contributed ta both the sand-

hills and the sandy plains. A considerable thickness of surface sand must

have covered the Pliocene soils ta enable extensive sand dune areas to form

within the tableland far removed from any Jurassic sandstone outcrops, the

only other source of siliceous sand. Nof all the sand was, however, stripped

off or piled into these major dune areas, since there are still isolated sand-

hills superimposed upon the tableland clays in some localéties.

In addition to this Recent stripping and resorting of the safids from the

old land surface, sand derived from the Jurassic sandstones was alsa re-

sorted. This sand was formed from the sandstones after Pleistocene erosion

206

had removed the overlying Cretaceous beds, As a result of the redistribu-

tion of the sand, the depth of the surface sands of the soils varies greatly

over a stnall area and this in turn causes a complex vegetation pattern.

The gypsum and sodium chloride present in the soils must have accumu-

lated after the Pleistocene since these soluble salts would be among the first

leached out. It is certainly not suggested, however, that the sodium chloride

originated as “cyclic” salt. Gypsttm is particularly common in the heavier-

textured soils, that is, the Pliocene fossil soils and the soils formed from the

Pleistocene alluvia, It occurs within a few inches of the surface in the form

of spherical aggregates of micro-crystals and increases in quantity with depth

sometimes to the extent of forming crystalline lumps. Over the tablelands

of the Lake Eyre region sheets of gypsum (selenite) up to 15” in length and

§” thick protrude from the surface of very friable “bulldusty” patches, Gyp-

gum in the form of a loosely-cemented powdery mass is of general occurrence

on the slopes of the residual hills. It has already been pointed out that gyp-

sum (kopi) dunes are associated with the margins of salt lakes. Heavy de-

posits of gypsum are encountered in the bleached Cretaceous shale in which

opals are obtained at Andamooka atid Coober Pedy,

There is a correlation between the amount of gypsum in any site and the

moisture status. In the well-drained sandy soils gypsum is usually absent,

but it is heavy in the soils of the Mt. Eba depression and the Pliocene fossil

soils where drainage is impeded and where the moisture status is compara-

tively high because of the presence of crabholes, The quantities of gypsum

become even greater in claypans and salt lakes.

During the Recent period sandhills formed upon the soils derived from

the Pleistocene alluvia in some localities. Conditions became moister fol-

lowing this period of aridity, and colonization and stabilization of the sand-

hills with mulga im the south and canegrass further north tock place. How-

ever, some of the dunes superimposed upon the tableland, for example, in the

Wirraminna, Roxby Downs, Arcoona atea and some of those immediately

surrounding it are unstable, being scantily vegetated with shrubs like sand-

hill wattle (Acacia ligulate) and hop-bush (Dodonaea aftenuats), species which

precede mulgas in the colonization of sandhills, These dunes are of more

recent origin, in fact were built up after the moister period when the stable

dunes were colonized with mulga. This indicates a change to somewhat

more arid conditions during very recent geological times,

The second piece of evidence in support of a theory of very recent in-

crease in aridity has already been given, namely, that under present climatic

conditions sodium chloride is accumulating as a surface crust on the salt

lakes whereas in the past there must have been a period when a salt crust

was absent (see Plate XVI, Figure 4). If this were not so it is difficult to ex-

plain the kopi dunes around the eastern margins of the lakes because this

gypsum has obviously been derived from the lake surfaces.

There remains to be discussed the origin of the lime in certain of the

soils. Lime cannot be detected in the least truncated Pliocene fossil soil

(Arcoona type) which is associated with the tableland country, but a trace

of lime can often be found in Coober Pedy soil, that is, where the clay of the

old land surface has been partly truncated. Coober Pedy soil profiles may

actually be underlain by travertine limestone. Trace to heavy lime is found

where all the clay has been removed from the Pliocene soil and bleached

Cretaceous shale is exposed. Where the Cretaceous beds have been com-

pletely or almost completely eroded away heavy accumulations of lime are a

constant feature of the soils, The amount of lime in the soils is therefore

207

greater with increased truncation which is correlated with increasing soil

aridity. It has already been noted that the amount of gypsum in the soils

decreases as soil aridity increases.

In the soils with heaviest accumulations, the lime ts in the form of rubble

overlying hardpan which is underlain by more rubble and friable lime. Small

iron-coated billy pebbles are scattered through the lime zone.

The presence of billy pebbles in the lime zone suggests that Crocker’s

(1946) loessial theory probably accounts for the origin of the lime in the

soils. Jack (1921) has suggested that gypsum is formed in the Cretaceous beds

as a result of the interaction of lime and sulphates derived from iron pyrites,

The writer has already pointed out that calcium is present in the fortn of

carbonate in well-drained soils with low moisture status, while more and more

of the calcium is present as gypsum in poorly drained sites, that is, gypsum

accumulates where the moisture statits of the soil is sufficient to enable sul-

phates and lime to react and leaching cannot take place. This explains why

ealcium can have originated as loessial lime and yet the boundary between soils

with no lime (but heavy gypsum) and those with heavy lime can be sharply de-

fined.

From pédological evidence, therefore, we can distinguish four motsture

regimes during Recent geological times. The early Recent must have heen

arid heeause vegetation was largely destroyed. The desert sandhills were

built-up, the sandy A horizons were stripped from the Pliocene soils and the

surface sands in the sand sheets were re-sorted. Then rainfall must have

increased to allow colonization of the sandhills and sandplains with trees.

We have already noted that crystalline gypsum, frequently in the form of

Jarge sheets, is found on the tableland country today. This gypsum must

have been in solution to have been precipitated in crystalline form so that

during this moister period of the Recent there must have been a fairly shal-

low water table. This moist period then gave way to a drier one, during

which the gypsum crystals were formed. In this drier period the newer un-

vegetated dunes formed on the tableland and about its margins in some

localities. Rainfall was sufficient to prevent a salt crust from forming on the

surface of the lakes.

Rainfall has continued to decline to the present day. During this period

of increased aridity salt has accumulated on the surfaces of the lakes, Evi-

dence from the distribution of myall (Acacta sowdenii) — see vegetation sec-

tion—suggests that rainfall is now lower than it was when tree colonization

was taking place.

PHYSIOGRAPHIC PEATURES

The geological framework then is made tp of flat-lying sediments while

topographically the North-West consists of vast gently-rolling plains mostly

between 200 and 500 fect above sea level. The highest hills are Dutton’s

Bluff (920 feet) and Mt. Gunson (850 fect), while the bed of Lake Eyre is 39 fect

below sea level.

Hills and ranges are either residuals of the Pliocene landscape (Plate XVII,

Figure 1) or composed of granite or metamorphosed rocks. They are usually

less than 200 feet above the surrounding country. Much of the area is quite

featureless, so much so that tn some cases trigonometrical stations are located

on sand ridges. Faulting has played no part in the eleyation of the table-

lands or residual hills. These features are due to differential erosion, the

hills in particular owing their preservation to a thicker capping of billy-

The sandy southern and western portions of the North-West have a

drainage pattern made up of short watercourses ending in “swamps” which

208

contain water orily after heavy rains. Further north the tableland country is

drained by well-defined creeks which run in an easterly direction and dis-

charge water into Lake Eyre after heavy rains. Before they reach the lake,

however, they flood out and consist of a mass of interlacing channels and

long narrow waterholes. Practically all these “lakes” are really saltpans —

depressing flat expanses with a salt crust or saline mud surface. Portions

of the salt lakes are firm and will support a motor vehicle but elsewhere,

particularly near the mouths of watercourses and creeks, they are very boggy.

During exceptionally wet seasons which may occtir one year in every ten, a

few of the freshwater “lakes,” for example Coolymilka Lake, Lake Richard-

son, Arcoona Lake and Lake Campbell contain appreciable quantities of

water. All of these lakes are depressions within tableland country. Even

the water in these becomes very brackish as they dry up.

Sandhills have an east-west trend in the southern portion of the North-

West, but in the north their trend is north-west to south-east. The sand has

been derived from two sources. Sandhills ia thé lower country surrounding

the tablelands have accumulated sand from Jurassic sandstones weathered

in site and from the Pliocene soils. The flats between them are sandy. All

the sand in the dunes which are superimposed upon the tableland has been

derived from the sandy A horizons of the Pliocene soil. If these dunes are

close together the interdune areas are sandy, but if they ate scattered the fats

between them consist of gibber-strewn clay soils of the Coober Pedy or

Arcoona types.

Claypans generally occur in association with sandhills, either in the hol-

lowed-out crests or more often on the flats between the dunes. They are flat

expanses of red clay of yariable shape but often roundish in outline and vary

from a few yards to several miles across (Plate XV11, Figure 2). The surfaces of

claypans are often littered with billy gibbers (Plate XVII, Figure 3), while

gypsum occurs at shallaw depths within the clay. After rains they may

contain an inch or two of water, yellow in colour due to suspended clay-

Ciaypans are not, however, restricted to sandhill areas, being frequently

developed in Coondambo ahd sometimes in Wirraminna soil areas. They

form in depressions where water containing suspended clay washed out of the

sandy soils tends to lie.

The following is a typical claypan profile:

0-18” red clay

18-24" brown clay with moderate gypsum

24-36” (continuing) grey clay with heavy gypsum

Sou.— Grotocy Recationsuirs. Tue Surrace Deposits

The type of soil developed upon the Cretaceous rocks depends essen-

tially upon the truncation that has occurred in the profiles. Over the table-

land areas where the Pliocene topography is fairly well preserved, the soil

overlying the Cretaceous shale is a reddish-brown clay with a surface mantle

of billy gibbers and rare glacial erratics which have weathered out of the

parent material, The surface which is gently rolling and slopes towards

drainage lines (creeks and watercourses) is characterized by a pattern of

depressions (crabholes) with mounds (puffs) around the lower side of the

crabholes, The clay is about 10 feet in depth and is underlain by bleached

shale except in the Kingoonya region where the clay soil directly overlies

Jurassic sandstone. In this area the Cretaceous beds were very shallow an

were completely weathered to clay. The soil whose sutface features are de-

scribed above, that is, the Arcoona type, is the least truncated of the Pliocene

209

fossil soils. Morphologically it represents the Pliocene profile minus the

sandy A horizons and some clay and with the siliceous B horizon broken up.

Shallower clay suils of the Coober Pedy type have resulted from either

Pleistocene truncation of Arcoona soil or were formed during the second

period of silicification from shale exposed by erosion which occurred in the

Pliocene inter-siliciication period,

The Pliocene profiles were completely removed over large areas in the

Pleistocene to expose bleached shale. The light red-brown soil subsequently

formed on the exposed shale is very shallow and has a surface cover of

bleached shale fragments and billy pebbles. This is Twins soil. Pleistocene

erosion nat only resulted in loss of part or all of the Pliocene soil from Coober

Pedy and Twins soi] areas but often caused complete or almost complete

truncation of the Cretaceous shale itself. Truncation of the shale had its

most important pedological effects towards the limits of the Cretaceous sea

where the beds were thin even when first laid down. All of this lower coun-

try surrounding areas where the Pliocene landscape is more or less preserved

is characterized by soils containing large quantities of lime. A very shallow

clay loam or clay soil overlying limestone hardpan was formed in post-Pleis-

tocene times in areas where a shallow layer of Cretaceous shale remained,

The limestone hardpan may overlie Jurassic sandstone or a shallow hand of

shale, depending upon the thickness of shale which survived the Pleistocene

erosion. This, the Wilgena soil, has its surface more or less covered with

iron-coated billy pebbles,

Two different sandy soils containing latge quantities of lime developed

where the Cretaceous beds were completely destroyed by erosion and the

underlying Jurassic sandstones were exposed, Not all the sand in the snils

was formed ix sifu from the underlying sandstones as some it was derived

from the surface of the Pliocene soils during the arid Recent. Very

shallow sands overlying limestone rubble and hardpan (Bon Bon soil) are

present in areas from which sand was stripped during the redistributions of

the arid Recent. Where comparatively deep red sand overlies limestone

(Wirraminna soil) either the sand was not disturbed during the Recent or

else these areus received some sand from the surface of the Bon Bon soil

areas. Further accumulation of sand results in the formation of sandridges

and sandhills. These aeolian accumulations may be superimposed upon a

variety of geological materials,

In the Miller's Creek-Billa Kalina area a very shallow brown clay loam

ur loam soil (Miller's Creek type) has formed upon siliceous limestone. This

limestone must have originated during the inter-silicifcation period of the

Pliocene because shale that was bleached during the first period of silicifica-

tion underlies it and biily pebbles (remnants of the siliceous B horizon ai

races formed during the second silicifcation period} are scattered over its

surface,

Two different types of soil have formed on Pleistocene alluvia. The Mt.

Eba soil which developed principally on alluvium in the Mt. Eba depression

and along watercourses feeding into it has a shallow sandy surface overlying

red clay. A mantle of billy pebbles occurs on the soil surface and billy

pebbles are buried in the profile. As it is formed from transported parent

material, Mt. Eba soil may overlie either bleached Cretaceous shale or

Jurassic sandstone,

Coondambo soil, which aiso is formed from Pleistocene alluvium, con-

sists of red clay overlain by shallow sand. Unlike the Mt. Eba soil, little or

no billy is associated, Jurassic sandstone underlies the soil at shallow

210

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AND GEOLOGICAL OUTCROP

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| ae aier ceetwea! eon gars Crevarvous sole cemecnes

it tl Tavas 4eif/— Blvothes Crefeceonr stale

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SO/L AND GEOLOGICAL OUTCROP PLAN

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SOL CONSERVATIGN BRANES

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Cretaceous

blue

shale

Jurassic or

Precambrian-

Cambrian

Pliocene

climate

sands

ferruginous

zone

(red clay)

bleached zone

siliceous

horizon

bleached zone

Cretaceous

blue shale

Jurassic or

Precambrian-

Cambrian

Pliocene

profile

Oricrn of THE Sorts FRoM GroLocica. Parent MATERIALS ILLUSTRATED DIAGRAMMATICALLY

gibbers

red-clay

bleached zone

Cretaceous

blue shale

Jurassic or

Precainbrian-

Cambrian

Arcoona

soil!

bleached zone

Cretaceous

blue shale

Jurassic or

Precambrian-

Cambrian

Coober Pedy

soil

gibbers

“redclay

soil

bleached zone

Cretaceous

blue shale

Cretaceols

blue shak

Jurassic or

Precambrian-

Jurassic er

Precambran-

Cambriar

Cambrian

Twins soil

INCREASING TRUNCATION -

sand

Further

—________| accumulation

Jurassic

Wirraminna

--! soil

_ soil

>>|bleached shale — >) Jurassic ecuate

ore re sandstone Resorting

i of sand

Jurassic

~Wilgena

" sand

Jurassic

Bon Bon soil

of sand

sand

Jurassic

Deep red

dune

rapl

depth around the salt lakes in the southern portion of the North-West where

the largest areas of Coondambe soil are found.

Summing up, then, the following are the ages of the soils—Arcoona and

Coober Pedy soils (Pliocene); Twins, Wilgena, Mt. Eba and Coondambo

soils (post-Pleistocene) ; Wirraminna and Bon Bon sails (post-Pleistocene

with Recent distribution of surface sands); and deep red dunes (built up

during the Recent).

The distributions of the surface deposits are shown on the soil-geclogy

plans (Figures 9 and [1).

Types or BILiy

Billy (fragments of the siliceous B horizon of the Pliocene soils) is not

senor in structure. Four types found in the North-West are described

elow,

(1) Vitreous: This form has 4 vitreous appearance on freshly broken

faces. It consists of quartz sandgrains and small milky and smokey quartz

pebbles cemented together by silica. The surface of vitreous billy gibbers is

irregular becattse the quartz pebbles are more resistant to weathering than

the siliceous cement. Large stones of vitreous billy are iron-stained on the

surface only, but the small stones may be completely iron-stained except for

the quartz pebbles and sandgrains.

The proportion of quartz pebbles and sandgrains to siliceous cement

vaties considerably. If there are no pebbles and few sandgrains the stones

have a smooth surface and a characteristic fracture, breaking up into angular

pieces. Because of this quality this type of vitreous billy was commonly

used by aborigines for spear heads.

(2) Black: This form of billy is heavily iron-stained right through. It

consists of a mass of coarse quartz sandgrains cemented by varying propor-

tions of ferruginous silica and yellow and red ochre.

It has no particular fracture but weathered surfaces are pitted because

the sandgrains are more resistant than the cementing material. Another

characteristic of the weathering of black billy is the tendency for layers to be

irregularly removed from the surface of the gibbers due to the variation in the

hardness of the cementing materials.

(3) Grey billy: Grey billy consists of a homogenous mass of grey-white

silica which fractures irregularly. Weathering produces a fairly smooth surface.

(4) Conglomerate billy: This consists of waterworn pebbles and

small stones of vitreous or grey billy and milky quartz cemented together by

silica.

The individual pebbles of vitreous billy within the conglomerate gib-

bers have red-brown iron-stained surfaces. This iron-staining of the pebbles

resulting from break-up of the siliceous B horizon formed during the first

period of silicification in the Pliocene indicates that conditions must have

been arid during a portion of the inter-silicification period,

The surface of conglomerate billy weathers very unevenly because the

pebbles and stones that have been cemented together are more resistant to

weathering than the siliceous cement.

THE SOILS

CLASSIFICATION

Prescott (1944) has recognised eighteen soil formations or zones in Aus-

tralia, four of which are represented in north-western South Australia, These

are

212

A. Stony and rocky areas relatively free from soil.

This formation includes ranges of the arid regions of which the Denison

Range is an example.

B. Desert formations.

' Prescott suggested four desert t-fortiarions three of which (desert sand-

hills, stony deserts and desert loams) are represented in the North-West,

The “stony deserts” include a variety of unrelated soils, but in South

Australia they are areas consisting of the Arcoona and Coober Pedy soils

described herein. It is suggested that these soils. in which the surface stone

consists of billy gibbers and which are associated with a partially dissected

tableland topography be called stony tableland soils. The term “desert

loam" first used by Prescott (1931) is unsuitable for two reasons. In the

first place the surface horizons of the soils belonging to this group range in

texture from sand to clay and secondly ‘desert loam” soils occur in South

Australia in areas with an average annual rainfall as high as 11-12”. As the

“desert loams” are the earthy (in contrast to the stony and calcareous) soils

of the arid regions it is proposed that they be called arid red earths. A

hitherto undescribed group of caleareous soils have been designated cal-

careous arid soils, These are the arid members of the calcimorphic soils

which end with the rendzinas and terra rossas.

The new classification for the arid soils occurring in the North-West is

set out below:

Order Sub-order Great Soil Group Families

Coondambo

Mt. Eba

Coober Pedy

Arcoona

Twins

Arid red earths - -

— ere,

Stony tableland soils

Wilgena

Miller’s Creek

Bon. Bon

Wirraminna

Pedocals - Arid soils =~ C€alcareous arid soils

SS Se ay

Wirraminna

(in part)

Red sandhills

Deep red dunes - -

——

Arinl ranges - - - Denison

GENERAL CHARACTERISTICS OF THE SOILS

Soil horizons are not clearly differentiated and salinity is high except

in the deep sands because the soils, as they occur in the present geological

period, undergo little or no leaching.

Very shallow A horizons are a feature of all the soils except the very

sandy ones as natural erosion in low rainfall areas is much greater than in

higher rainfall country and the rate of soil fotmation is slower. Even in

unstocked areas, during drought periods the soil surface is poorly protected

by plant growth.

The soils range in colour from brown to red and in texture from sand

to clay. They are generally poorly structured. Depending on their drainage,

213

they contain either heavy lime or heavy gypsum. Billy pebbles or gibbers

are associated with all the soils of the North-West with the exception of the

aeolian eandridges, bit this is not a universal feature of arid soils.

Tere Sow Famicies

Arcoona soil

This residual Pliocene [fossil soil formed from Cretaceous shale is found

on the tableland country, that is, where the Pliocene land surface is least

eroded. The tableland is a gently-rolling plateau which is elevated 300-350

feet aboye the surrounding country around its southern limits.

Depressions (crabholes) with a roughly circular or irregular shape and

varying in size usually from 10-50 feet across are a feature of the soil sur-

face. The crabholes are 4-24” deep, Puffs (Plate XVII, Figure 4) 3-12” higher

than the shelves are formed around the lower sides of the crabholes which

vary from 10-40 yards apart. The height of the puffs mcreases as. the sur-

face slope incteases, Gently-sloping gibber-covered shelves separate the crab-

holes.

Water does not normally penetrate the shelf profile to a greater depth

than a few inches, run-off water working its way between the, gibbers on

the shelf surface into the crabholes, When the crabholes higher up the slope

become full of water further rain causes a flow of water to the crabholes lower

down the slope. The presence of crabholes means that water only drains

off the tableland after exceptionally heavy rains. The clay is easily dispersed

with the result that crabhole water is always yellowish in colour immediately

after a rain, but the suspended clay soon settles due to the presence of large

quantities of gypsum.

Shelf ateas constitute a very arid and saline environment and support

only a very sparse growth of bindyis and samphire. Saltbushes (Atriplex

vesicaria and A. rhagodioides) and the Composite [rielaena leptolepis are the domi-

nant shrubs in the crabholes. Due to the heavy texture of the soil, trees are

absent except along creeks and watercourses. Although Arcoona soil areas

respond quickly to rain and grow more nutritious species than the sandy

country they have a fairly low stock carrying capacity because plant growth

is practically restricted to the crabholes.

A texture profile is not developed as clay is present on the surface, but

salts are zoned according to their solubilities. Lime cannot be detected even

with acid, but gypsum is always present at shallow depth and becomes heavy

below. Where it is heavy the gypsum is present im bands, a soil horizon

containing heavy gypsum being followed by one without gypsum. Near the

soil surface it occurs in spherical clusters of white micro-crystals, but where

it ig heavy gypstim seen in a pit-face resembles the appearance that flour

would have if dusted across the face of the pit.

The following is a typical shelf profile:

0 — 3” brown (5 YR 6/6) “™ light clay with caked structure contain-

ing a veal of gypsum and heavy billy gibbers. (boundary fairly

definite).

4-5” reddish-brown (5 YR 6/8) structureless clay with slight gyp-

sum and a trate af billy gibbers (boundary very diffuse).

() The figures refer to the Munsell chart of sail colours, The American interpreta-

tion of these colour standards into colour terms has not been followed.

214

5-16” red-brown (2,5 YR 5/8) massive clay with medium gypsum and

a trace of billy gibbers (boundary very diffuse).

16-22” red-brown (2.5 YR 5/8) massive clay with slight gypsum (sharp

boundary).

22-48” reddish-brown (5 YR 6/8) massive clay with heavy gypsum.

The laminated structure (an extreme case of “surface sealing’) of the

surface horizon of the shelf profile is interesting. Taylor (see Crocker and

Skewes 1941) considers that the mechanical action of raindrops on a wet sur-

face dispenses the surface layer of a sodium-saturated clay.

Polished brown or reddish-brown pebbles and stones (gibbers) 1” to 2 feel

across and of irregular outline more or less cover the shelf soil surface. The

bigger pieces are in the form of flat plates. The gibbers are grey-white inside

and consist principally of grey and some vitreous billy. Glacial erratics of quartz

and quartzite weathered out of the parent material are of rare occurrence.

A typical crabhole profile is given below:

—#" grey-brown (5 YR 6/6) sand with light billy gibbers (sharp

boundary).

4— 4" grey-brown (7.5 YR 6/6) clay with angular cloddy structure

(boundary diffuse).

4-16” brown (5 YR 5/6) massive clay (boundary diffuse).

16-26" brown (5 YR 5/6) massive clay with slight gypsum (boundary

diffuse).

26-36" brown (5 YR 5/6) massive clay with heavy gypsum.

Crabholes may be gibber-free or carry a few surface stones. Large

cracks form in the erabholes when they dry out.

The following is a typical puff profile:

O-— %” light reddish-brown (5 YR 7/6) sand with heavy billy gibbers

(boundary definite).

$- 1” light reddish-brown (5 YR 6/6) irregular nutty structured clay

with heavy gibbers (very diffuse boundary).

1-9 reddish-brown (5 YR 5/6) nutty clay with medium billy gibbers

(boundary sharp).

9-17" red-brown (2.5 YR 5/8) coarse nutty clay with light billy gib-

bers and slight gypstm (boundary sharp).

17-24" red-brown (2.5 YR 5/8) structureless clay with light billy gib-

bers and slight gypsum (boundary sharp),

24-36” reddish-brown (5 YR 6/8) structureless clay with heavy gyp-

sum.

Figure 5 shows the structure of the clay and the depth at which slight

and heavy gypsum appear in the shelf, crabhole and pu profiles.

Coober Pedy soil

This is a residual Pliocene fossil soil which has been more heavily trun-

cated than the Arcoona soil. Crabholes may or may not be present, depend-

ing upon the depth of the soil. There must be at least two feet of clay over-

lying the parent material for crabholes to be formed. When they are present

they are smaller and generally more scattered than those associated with

Arcoona soil. The depressions vary from 3-40 feet across and 3-10" in depth.

Puffs are absent in flat country and smaller than those associated with

Arcoona soil on sloping land.

A shallow solonized (bleached) horizon 1/,, ’-1” thick is usually present within

an fich or two of the soil surface in the shelf profiles. Gypsum is always present,

215

appearing at depths of 3-24”, It may be only a trace throughout the profile but it

usually becomes moderate or heavy with increasing depth. Most shelf profiles

contain a trace of lime which usually appears at depths of 6-24”. The lime is

generally only present in the profile for a few inches. While Coober Pedy soil

normally rests on bleached shale occasional profiles are underlain by lime hardpan.

Billy gibbers 4-12” across more or less cover the surface of the shelves,

ot where crabholes are absent, the whole of the soil surface (Plate XVIII, Figure

1). Vitreous billy predominates but some grey billy is present, Rare quartz

and quartzite glacial erratics from the Cretaceous shale also occur on the sur-

face, the smaller pieces of billy and the quartzites having iron-stained sur-

faces, Stone in the profile varies from heavy near the surface to trace or

none below.

AEY 70 S0lt STRUCTURE \

LINGLE CRALN (EastO)

Pere —Sj care

Cc STRUCT ERELIES

werry

a) awetias ceons

Arassie

tae te RB eww AH DS

AERA SM LNENES

Fig, 5

Showing the structure of the clay and the depths

at which slight and heavy gypsum appear in the

shelf, crabhole and puff profiles of the Arcoona soil.

The following is a typical shelf profile:

0-1” red-brown (2.5 YR 6/8) slightly laminated sandy loam of finely

vescicular stricture containing heavy billy gibbers (boundary

fairly sharp but irregular).

1~— 6" dark red (2.5 YR 3/6) angular nutty clay with a trace of billy

gibbers (boundary sharp),

6-14” red (10 R 5/8) nutty to crumb structured clay (boundary very

diffuse),

14-24” lightish red (2.5 YR 5/8) angular nutty to crumb structured

clay with a trace of billy gibbers (boundary fairly sharp).

24-32” brownish ted (2.5 YR 4/8) clay of angular blocky to crumb

structure with slight lime and slight gypsum (boundary sharp).

32-40” red Sh R 5/8) massive clay with medium gypsum (boundary

sharp).

216

The surface horizon varies in texture from sandy loam to clay, while

some profiles have brownish-red clay throughout the B horizons,

As indicated below, crabhole profiles are similar to those of the Arcoona

soil except that a trace of lime is usually present:

0-12” brown clay,

12-20" brown clay with a trace of lime.

20-24” brown clay with heavy gypsum.

Coober Pedy soil areas carry saltbush (Atriplex vesicaria) as the domi-

nant species and have a fairly low stock carrying capacity. Growth is prac-

tically restricted to the crabholes where they are present, while a sparse

growth of saltbush occurs scattered over the whole surface where crabholes

are absent.

Twins soil

This residual soil developed upon bleached Cretaceous shale is charac-

terized by a very shallow profile without gypsum. The soil surface is lit-

tered with whitish shale fragments 4-3" in size and iron-stained billy pebbles

3-8” across. Vitreous billy predominates but grey billy is common. In addi-

tion rare giactal erratics of quartz and iron-stained quartzite lie on the sur-

face. Jasper is present on the surface and through the profile where the

shale has been silicified.

The soil consists of light reddish-brown to light red-brown loam, clay

loam ot sandy clay loam subsoil overlain by shallow red-brown sand or light

reddish-brown to light red-brown sandy loam as illustrated by the following

0-4” red-brown (2°5 YR 4/6) sand with heavy bleached shale frag:

ments and billy pebbles (boundary sharp).

4-3” light reddish-brown (5 YR 6/4) loam to clay loam with weak

crumb structure and containing slight lime (boundary diffuse).

3-5” light red-brown (2.5 YR 6/6) clay loam with crumb structure and

containing light lime and heayy bleached shale fragments (boun-

dary fairly sharp).

5-8” mixed brown soil, lime rubble and shale fragments. The colour

of the soil fraction is light reddish-brown.

The sand horizon may be absent and even in areas where it occurs the

sand is found principally around plant growth, Lime is not always as heavy

as ihat indicated in the above profile, in fact, it is occasionally absent alto-

gether.

Twins soil catries treeless shrub steppe vegetation dominated by blue-

bush (Kochia plonifola). The poor water-retaining capacity of the soil has

resulted in widespread bush death under dronght conditions even in ungrazed

paddocks, with the result that living bush is practically confined to water-

courses and slopes of undulations which receive run-off water. Grass and herbage

only grow in large quantities on Twins soil during very good seasons,

bilgena soil.

This residual calcareous soil has a shallow profile over lime hardpan.

The surface is more or less covered with billy pebbles (Plate XVII, Figure 2).

Wilgena soil is found in country from which the Cretaceous deposits have

beet: largely eroded away. The profiles may overlie shallow bleached Cre-

taceous shale or, where the shale has all weathered to soil, Jurassic sandstotie,

The Wilgena soil shows the influence of two parent materials. At the present

217

time the parent material is the lime rich layer, but the billy pebbles are a

residue from the originally overlying older soil formed from shale. This older

soil has also influenced the texture of the Wilgena soil,

The surface soil is reddish-brown, light reddish-brown or light red clay

loatt, sandy loam or rarely light clay. A sand horizon up to 4” in thickness

sometimes occurs on the surface. The subsoil is reddish-brown or light reddish-

brown clay loam, sandy clay loam or light clay. Lime may be present from the

surface and heavy lime (rubble or hardpan) always occurs between 4” and 9”.

A heavy accumtilation of pebbles and stones generally }” to 4” in diameter

occurs on the soil surface and in the top of the profile. On the tops of some

hills the billy occurs in the form of boulders up to 12-18” across. Vitreous billy

predominates but some grey and conglomerate type billy is also found, while Creta-

ceous quartzite and milky quartz glacial erratics are of occasional occurrence, The

smaller billy stones and the quartzite have an iron-stained red-brown surface,

The following is a typical profile:

0-4" light red (25 YR 6/6) clay loam with a cakey somewhat laminated

structure and containing medium lime. The surface is covered with

billy pebbles and some lime flakes (boundary fairly sharp).

4-4" light reddish-brown (SYR 6/6) clay loam containing heavy lime

rubble. This overlies lime pan.

Wilgena soil supports 2 shrub community dominated by bluebush (Kochia

sedifolia), but scattered trees of mulga ot myall may be associated. The ground

layer is dominated by bindyis (Bassta spp.) and grasses (principally Erneepogon

spp.). The density of bluebush is Jower on this type of soil than it is on Bon

Bon soil and the growth of herbage and grass is always. sparse.

Bon Bon soil

Bon Bon soil is a residual calcareous soil with a fairly shallow profile over-

lying lime rubble and hardpan. Morphologically it differs from Wilgena soil in

three ways. The heavy lime layer generally occurs at slightly greater depth, while

the soil is lighter in texture and only has a trace of stone associated with it.

Red-brown satid up to about 6” deep overlies reddish-brown or light-brown

sandy loam with light red-brown or light reddish-brown sandy clay loam or

loam to clay loam below. The sandy loam horizon is absent in the shallowest

profiles. Lime is always present at, or within a few inches of, the soil surface

and becomes heavy (rubble and hardpan) at depths of I-10”, Flakes and

pebbles of limestone 4”-2” across and very rare iron-stained billy pebbles

}'-2” in diameter are scattered across the soil surface. A trace of billy pebbles

usually occurs in the profiles,

A typical profile is given below:

0-2” red-brown (2°5 YR 5/8) sand,

2-5" light red-brown (5 YR 7/6) crumb structured sandy loam with

moderate lime.

5-12” light reddish-brown (5 YR 6/6) structureless sandy clay loam with

heavy lime.

12-16" lime hardpan.

16-20” brown clay loam with moderate hme.

20-33” brawn clay loatn with moderate lime and a trace of gypsum.

33-54" light reddish-brown clay loam with light lime and slight gypsum.

54-72” brown clay loam with light lime and a trace of gypsum.

Wirraminna Soil

Areas with sandy soils received sand from several different sources and the

sand has undergone considerable re-distribution during the arid Recent, Where

213

Wirraminna soil occurs in extensive sheets across the country, the sandy horizons

have largely resulted from the weathering of underlying Jurassic sandstones.

Throughout large areas of the North-West aeolian sandridges alternate with

Bon Bon soil areas, Much of the sand in the ridges has been stripped from the

intervening soils, Sand from the Pliocene soil has also contributed to the sand

sheets and ridges.

As a result of the resorting of surface sands which occurred in the Recent,

the sandy horizons of the Wirraminna soil vary considerably in depth. The

deepest sands are found in the sandridges which gtade into sandhills, while with

decreasing depth of surface sand Wirraminna soil grades into Bon Bon soil.

The amount of lime and the depth at which it appears varies with the depth

of sand. Trace to light lime occurs at considerable depth in the sandridges,

while in those areas where the sand forms extensive sheets heavy lime is found

at much shallower depth. Thus there are two variants of Wirraminna soil—

a small sandridge type of aeolian origin and the soils of the extensive sand sheets.

These variations in the depth cf the surface sands result in a complex yege-

tation pattern, On the deepest sands the dominant species ate mulgas (Acacia

ancura and A. brachystachya), while bluebush is absent, Where the surface

sands are shallower and lime is present nearer the surface, scattered bluebushes

(Kochia sedifoliz) appear among the mulgas. Finally bluebush forms a shrtb

layer beneath the mu)gas on the shallowest of the Wirraminna soils,

Wirraminna soil consists of up to four feet of red sand (deepest in the

sandridge type) overlying clayey sand or sandy loam. The subsoil is browsish-

red, reddish-brown or red (the latter in the sandridge type only) sandy clay

loam. Lime is present at depths of between 8 and 50” and except in the sand-

ridge type becomes heayy with depth. Rubble overlies friable lime but hardpan

is also common, Some of the profiles on Commonwealth Hill station have up

to three feet of sand directly overlying limestone hardpan about two feet in thick-

ness with lime rubble below. Mine shafts at the Glenloth goldfield indicate a lime-

rich layer four feet in thickness overlying the Precambrian rocks with hardpan

varying from 3-12” in thickness. Billy pebbles are absent in all but the shallowest

af the profiles and even then only a trace of stone occurs, Gypsum was found

in a few profiles at depths of 4-5 feet but can rarely be detected,

The following profile is typical of the soils of the sand shcets:

0-18” brownish-red sand.

18-23” red-brown sandy loam.

23-26" red-brown sandy clay loam.

26-30” reddish-brown sandy clay loam with light lime.

30-32” reddish-brown sandy clay loam with moderate lime,

42-36" reddish-brown sandy clay loam with heavy lime.

36-45” grey-brown sandy clay loam with heavy lime,

A typical sandridge profile is given below :

0-29" red (10 R 4/6) sand (boundary diffuse),

20-40” red (10 R 4/6) sand with light lime (boundary fairly diffuse).

40-41” pale red to red (2°5 YR 6/2) and (2°5 YR 4/6) clayey coarse sand

in the form of an indurated massive pan bleached through soloniza-

tion (boundary sharp).

41-53” red (10 R 4/6) massive sandy clay loam.

Miller's Creek soil

In the Miller's Creek - Billa Kalina area siliceous iimestones formed during

the inter-silicification period of the Pliocene are exposed. They are underlain

219

by Cretaceous. shale which was bleached as a result of leaching during the first

period of silicification, while a siliceous soil profile formed upon the limestones

during the second period of silicification. Subsequent erosion removed the soil,

leaving only billy pebbles on the surface of the limestone upon which a very

shallow soil has subsequently formed, Jt is heavy-textured (clay loam or clay)

and contains lime and sometimes gypsum. Pieces of siliceous limestone }-4”

across and occasional iron-coated billy pebbles 4-1” in diameter occur on the

surface of the soil.

The following is a typical profile:

0-3” brown clay with light lime.

3-6” brown clay with light lime and a trace of gypsum.

Miller’s Creek soil carries bluebyshes (Kochia planifolig and K, sedifolia)

and saltbush (triplex vesicaria). Its poor water-retaining capacity is reflected

in the sevete bush death that has occurred even with the extremely drought-

resistant Kochia sedifolia, The growth of herbage and grass is always sparse.

Mt. Eba soil

Mt. Eba soil is developed upon Pleistocene alluvium mainly in the Mt. Eba

depression and in the broad watercourses which drain into it,

The following features are typical of the soil

: Surface stone—The soil surface is mote or less covered with pre

iron-stained pebbles ranging from }$-3” in diameter, the majority being 4-4"

diameter (Plate XVIII, Figure 3). These pebbles consist of vitreous and her

billy and rare conglomerate billy, quartz and quartzite. The surface of the quartz

pebbles is not iron-stained.

Stone through the profile—Heayy acctimulations of pebbles occur in the

profiles for the first few inches (sometimes up to 12”), then trace to light stone is

found to the bottom of the profiles or it may be heavy again above the under-

lying rock.

Surface soil—The surface soil is most commonly a 3” horizon of reddish-

brown or sometimes red sandy clay loam but rarely red clay loam overlies the

subsoil clay. Other profiles have shallow brownish-red sandy loam and/or

4-4” of red sand overlying the sandy clay loam,

Subsoil—Clay subsoil occurs at depths of 4-10’, The upper portion of the

clay is generally reddish-brown in colour but it becomes red below. Trace to light

lime is encountered between 9 and 36’. The lime usually remains trace or light

but sometimes becomes moderate with increasing depth. Gypsum is usually

present at depths of between 12” and 30%. It is often moderate and rarely

becomes heavy with increasing depth,

A typical profile is set out below:

0-3” reddish-brown sandy loam.

3-6” reddish-brown sandy clay loam,

6-9" brownish-red clay.

9-12” brownish-red clay with light lime,

12-21” brownish-red clay with light lime and light gypsum.

21-34" red clay with light lime and light gypsum.

3442” red clay with light lime and moderate gypsum.

42-54” reddish-brown clay with bleached shale fragments.

This soi! may carry mulgas but the characteristic feature of the vegetation

ig the dominance of the ground layer by bindyis {principally Bassia divaricate,

8B. paredoxs and B, uniflora),

220

There are two other variants of the Mt. Eba soil. The first occupies low

terraces between watercourses, that is, slightly more elevated sites than the soil

described above, and while similar in other respects has a light reddish-brown

sandy clay loam solonized (bleached) zone 4-2” thick overlying the clay.

The following profile is typical of this soil type;

O04” red (2-5 YR 4/8) sand (boundary definite).

+1” brownish-red (2°5 YR 5/8) structureless sandy loam (boundary

irregular but fairly definite),

1-3” light reddish-brown (5 YR 6/6) somewhat domed sandy clay loam

bleached horizon (boundaty very irregular).

3-11” red (10 R 4/6) clay witha nutty to angular crumb structure (boundaty

diffuse).

11-20" brownish-red (2-5 YR 4/8) clay with irregular nutty to crumb

structure and containing light lime and a trace of gypsum (boundary

diffuse).

20-44” brownish-red (2°5 YR 4/8) clay with irregular nutty to crumb struc-

ture and containing light Ime and medium gypsum (boundary more

or less abrupt).

This soil type supports a scattered growth of bluebush (Kochia planifalia)

in addition to bindyis,

The other variant of the Mt. Eba soil occurs in the bottoms of watercourses

in the Mt. Eba depression, that is, in the lowest sites, Red clay subsoil which is

encountered between 0” and 7” may be overlain by shallow red sand or red sandy

loam (or sandy clay loam) and shallow red loam (or clay loam). Lime, when it is

present in the profile, occtits between 12” and 18” from the surface, It may

become moderate or heavy in amount with increasing depth. Gypsum is

encountered between 26” and 45”. This soil type has a redder surface, deeper

gypsum and lighter stone on the surface and through the profile than the other

Mt. Eba soils.

A typical profile of this type is set out below:

0-3” red sandy clay loam.

3-6” red clay loam.

6-18" red clay.

18-30” red clay with a trace of lite.

30-45” brownish-red clay with light lime.

45-48” light reddish-brown clay with light lime and light gypsum.

Soil with this type of profile carries mulgas, dead finish (Acacia tetragano-

phylla) and bindyis.

A feature of the Mt. Eba soils, especially in areas liable to fairly frequent

inundation, is the presence of “sinkholes”, small crabholes of irregular shape

with either sloping or vertical sides. The largest holes are about three feet across

and one foot deep, but holes 6-12” across and 6% deep are most common, Puffs

are not developed around the holes nor do shelf areas separate them. The lowest

portions of small “swampy” areas, for example, may simply have half-a-dozen

of these holes in them.

Coondambo sail

This arid red earth is formed from Pleistocene alluvium in low sites such

as around salt lakes, in watercourses and around the lower slopes of hills and

tablelands, The underlying rock occurs at depths of 6” to 4 feet.

221

The following features are characteristic of Coondambo soil:

Surface soil—The surface horizon consists of red sand 42” in thickness

except in watercourses where it is usually deeper. This is underlain by either

light red-brown to red-brown loamy sand, sandy Joam, sandy clay loam or rarely

loam or clay loam.

Subsoil—Red clay which often becomes sandy or gritty with increasing

depth occurs between 3” and 15” from the surface. A very shallow solonized

(bleached) horizon frequently overlies the red clay. Trace to light lime is found

at depths of 14-30” and may increase to medium at greater depths. Trace to

light gypsum which often becomes moderate with increased depth appears at

12 ’

Stone—Stone is generally absent but trace to light billy pebbles usually not

exceeding 1” in diameter but rarely 4-5” across may be present.

The following is a typical profile:

O4” red (2-5 YR 4/6) coarse sand (boundary sharp).

4-3” red-brown (5 YR 4/6) massive loamy sand (boundary sharp but

irregular).

3-44" light red-brown (5 YR 6/6) loamy sand. This bleached horizon has

a slightly domed structure (boundary sharp).

44-15" red (2*5 YR 4/6) massive light clay (boundary fairly sharp),

15-20" dark red (10 R 4/4) massive sandy light clay with slight gypsum

and light lime (boundary fairly sharp).

20-31" red (2°5 YR 5/8) crumb structured sandy light clay with slight

gypsum and light lime (boundary fairly sharp},

31-45" red (2-5 YR 4/8) crumb structured sandy light clay with medium

lime and trace of gypsum.

Very shallow soil profiles of the Coondambo type which are superimposed

tipon Bon Bon or Coober Pedy soil occur on flats between sandhills in some

localities, These Coondambo soils have originated in the same way as claypans,

that is, by downward percolation through the sandhills and subsequent drainage

on to the flats of water containing clay in suspension. This downward percola-

tion and outward movement of water from the base. of the dunes probably occurred

during the moist period of the Recent referred to in the chapter on geology, A

patchy cover of sand over the clay has resulted both from washing and blowing

of sand from the foot of the dunes.

Coondambo soil areas carry a very dense growth of saltbush (Atriplex

vesicaria) and bluebtsh (Kochia planifolia) and have a greater stock carrying

capacity than any other type of cotintry in the North-West.

Deep red dunes

The sandhills are aeolian formations built up during the Recent arid period.

Under subsequent moister conditions the dunes were colonized by mulgas (Acacia

linophylla and .A. ramulosa) in the south and sandhill canegrass (Zygochloa

paradowa) in the Anna Creek - Oodnadatta area, so that they are now all fixed

dunes.

The source of the sand, nature of the interdune areas and the trend of the

dunes have already been discussed, Red sand (10 R 4/6) to a depth of more

than 9 feet (the maximum depth of boring} is characteristic of the crests of the

dunes. Down the slopes variable depths of red sand (depending upon the dis-

tance from the crest) overlie red clayey sand. This clayey sand horizon has

resulted from downwatd persolation of water containing suspended clay.

The distribution of all the soils is shown in the soil plans (fig. 9 and 11}.

222

Erosion

Natural erosion of soils carrying native vegetation in arid areas is consider-

ably greater than in higher rainfall areas. Most erosion occurs during drought

years when the soil surface is not perfectly protected even where the original

bush cover is not depleted through stocking. Thus mounds of soil always

accumulate around the bushes eyen in unstocked country. Partly as a result of

this natural erosion, all the arid soils except those consisting of sand accumula-

tions have shallow A horizons,

No measurements of soil loss caused by accelerated erosion have been made,

as estimates on the basis of profile comparisons are considered impracticable on

account of the natural variations in depth of the A horizons. However, it is the

general impression that accelerated erosion has been insignificant throughout most

of the North-West but moderate in a few localities.

From the point of view of erodability the soils may be divided into three

groups: (1) those with a surface mantle of stones; (2) soils with sandy A hori-

zons; and (3) Miller’s Creek soil which is heavy-textured and has little surface

stone. Included in the first group of soils are the Mount Eba, Coober Pedy,

Arcoona, Wilgena and Twins types. The surface cover of stones helps to protect

the soils from wind erosion, especially in the case of Arcoona and Coober Pedy

soils where the stones ate large and the covet is more complete. While most of

the North-West is not prone to water erosion, the Arcoona and Coober Pedy

soils would be if it were not for the surface stone and the crabholes on account

of the topography with which they are associated. Of the five stony soils Twins

soil has suffered greatest erosion.

With the exception of Coordambo soil, the soils with sandy A horizons

(Wirraminna, Bon Bon, Coondambo and deep red dune soils) carry a fairly dense

growth of trees and are therefore well protected from wind action, However,

tree death is widespread and there is little regeneration, so that eventually a severe

erosion problem can be expected on these sandy soils.

Coondambo soil with its very shallow sandy horizons overlying clay subsoil

is liable to the most serious damage by wind erosion. Moderate sheet erosion

has occurred in some areas but most.Coondambo soil is jocated around saltlakes

where it is difficult to obtain tndergrotind supplies of stock water, with the result

that these ateas are largely ungrazed. Soil loss from Miller's Creek soil areas

has been moderate because widespread bush death has occurred on account of

the poor water-retaining capacity of the soil.

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227

THE VEGETATION

CLASSIFICATION OF THE PLant ComMUNITIES

In this survey the basic unit used im the classification of the vegetation ‘is

the plant association as defined by Crocker and Wood (1947), and wherever

possible this unit has also been used in the vegetation mapping (Figures 8 and 10).

The associations and the factors determining their distribution are set out ‘in

Table X. However, over large areas certain of the associations are constantly

grouped together and it has not been possible to map the individual associations

on the scale used in the survey (two miles to the inch). In any case, from a

practical viewpoint these association groups form definite land types.

TABLE X

Association Soil Geology Annual rainfall Formation

Acacia linophylla— deep red dunes Recent sand- 54-72” arid woodland

A. ramulosa hills

Zygochloaparadoxa deep red dunes Recent sand- <54” desert sclero-

hills phyllous grass-

land

Acacia aneura — Wirraminna, Recent sand 43-73" arid woodland to

A. brachystachya Bon Bon and and clay shrub-arid

Wilgena woodland

A. sowdenii — Bon Bon and Recent sand 54-9" shrub-arid

Kochia sedifolia Wilgena and clay woodland

Atriplex vesicaria Coober Pedy Cretaceous 5-9" shrub steppe

+ Bassia spp. shale

Atriplex vesicaria Coondamba Pleistocene §-9" shrub steppe

~ Kochia planifolia alltivinm

K, sedifolia Bon Bon and Recent sand 5-9" shrub steppe

, Wilgeia and clay

Acacia aneura — Mt. Eba Pleistocene 54°—6" arid woodland

A. brachystachya = alluvium

A. tetragonophylla

K, planifolia— Mt. Eba Pleistocene 54°—~6" shrub steppe

Bassia spp. alluyium

Eremophila Arid ranges Precambrian — arid hill

freelingii — woodland

Acacia aneura—

A. brachystachya

Atriplex vesicaria Arcoona Cretaceous 53-0” shrub steppe

— Ixiolaena shale

leptolepis

A. rhagodioides Arcoona Cretaceous <5” shrub steppe

shale

Kochia planifolia Twins Cretaceous 5--7" shrub steppe

shale

Kochia planifolia— — ‘Miller’s Pliocene (?) 53” shrub steppe

Atriplex vesicaria — Creek Limestone

K. sedifolia

e—————— eee

228

In past ecological studies in South Australia the “edaphic complex” (see

Crocker and Wood, 1947) has been widely used as a mapping. unit but it has been

applied to two different types of complexes. It has been used in the mapping of

areas where two or more floristically unrelated plant associations are randomly

ASSOCIATION COMPLEXES DUE TO THE PRESENCE OF SANDHILLS

cose,

(29 ’

ASSOCIATIONS Lingvipllat A easira —

LAND

SURFACE

AN ERAGE WOT H

}

SOIL WIRRAMINNA:DEEP RED! WiRRAMINNA

D : DUNE ¢{

BON BON =; = WIRRAMINNA PEEP REN

| The Gbave sequence ie nof Slucye muntoned as soma of the donas ere separated

by Wieraminna, sad flafe enly,

ip the olt— bluabush community 1s absent

Ertl Acona

vedrcena

—Bassia age. ~Aeccia

Fi rer

SURFACE

SOIL

ASSOCIATIONS

LAND

SURFACE

Soi

| Atryifex jAcone fF :

ASSOCIATIONS [verscania } dagniyllal Mesa eneure—

—Acane }—Kochia | —Aeckia: t—Mcorra | Aessia Smetyoteehya |

danifolia ! eumulosa; t H Fatia + ramudosa + 5

LAND

SURFACE

AGE WIDTH

ARGS)

DEEP: RED| : iDEEP RED!

BUN” {COONDAMBO; WIRRAMINNA — :COONDAMBO ;PETE TED! WIRRAMINNA

Fig. 6

or regularly distributed on different soils, for example, the Zygochloa paradoxa —

Triodia basedowii edaphic complex of the Simpson Desert (Crocker 1946)

where the Z. paradoxa association occurs on the sandhills and the T. basedouni

association occurs on the sandy flats between the dunes.

Secondly, the edaphic complex has been used, for example by Specht and

Perry (1948) in the “stringybark edaphic complex” of the Adelaide Hills, in the

229

sensé defined by Crocker and Wood who state; “.... We have used one feature

of the habitat, namely, allied sotls, associated with related floristic composition

of species as a basis for classification, Within definite climatic limits, associations

on nearly related soil types and with related floristic composition are grouped

together as an edaphic complex.”

If the term “edaphic complex” is to have any significance it is. obvious that

it should only be used in the sense of the definition, and that a new term must

be introduced into ecological nomenclature for the other type of complex. The

“association complex” is a group of two or more associations which occur on

unrelated soils and which show random distribution within an atea. Each indi-

vidual association invariably occtirs on the one soil so that within the complex

ASSOCIATION COMPLEXES

DUE TO THE PRESENCE OF LOW SANDY RISES

7 -

Acata anew — H Acacia Sonicluncd —

ASSOCIATIONS

as Acitin tratlysdache 4 Kachin sextilidie

LANO

SURFACE

AVERAGE WIDTH : {MILE

WIRRAMINNA {BON BON Ano WILGENA

t AbeAds : Acasta aneura — |

ASSOCIATIONS seddolia | Aegote brachyslachya!

LAND

SURFACE

AVERAGE WIDTH

ASSOCIATION COMPLEX DUE TO THE PRESENCE

OF WATERCOURSES SEPARATED BY LOW TERRACES

Acacta eneuru — , ’ Acacia aneure — . ae,

ASSOCIATIONS. |4 dechyeceulya— Axia plonhtn ~ A, brachystuck gee— Mochea planitetin —

A latrapeiprhylls Sassen 499 TA talraponyrhylig Fassia 450. i

LAND

SURFACE

t MT EBA i H M7 EBA i

Soi MrEBA ‘With BLeaAcHeo zone = MT EBA Swith BLEACHEO zone

Fig. 7

each association becomes a soil indicator. The Eucalyptus oleosa~E, dumosa

association which is found on the brown solonized soil flats and the E. angulosa —

Melaleuca uncinata association which occurs on the solonetz sandhills in the Mur-

ray Mallee (Jessup 1946) form an association complex, In the North-West a

particular expression of the association complex occurs as a consequence of the

regular and parallel spacing of the sand dunes. With this type of topography,

when the contours are traversed at right angles there is a regular repetition of

associations. For convenience this particular expression of the association com-

plex has been styled an association repetition on the vegetation map,

230

The association complexes occurring in the North-West are sct out in

fig, 6 and 7.

Only one of these complexes requires further discussion. The Zygochloa

paradoxa —— Acacia aneuwra—A. brachystachya —— Atriplex vesicaria — Bassia spp.

association complex occurs in the Lake Eyre region where sandhills are super-

imposed upon tableland. The flats between the dunes are sandy where they are

close together or clayey (Coober Pedy soil) where the dunes are scattered.

Acacia linophylla and A. ramulosa are absent, their place on the dunes being taken

by canegrass (Z. paradoxa). In contrast to the adjacent Simpson Desert (Crocker

1946), spinifex is absent from the sandy interdune soils which carry a modified

mulga community. Airiplexy vesicaria- Bassia spp, association occurs where the

flats separating the sandhills have clay soils.

The plant associations may be classified into fiye formations.

Shryb-steppe formation

This includes treeless areas dominated by shrub species belonging to the

genera Atriplex (A. vesicaria and A. rhagodioides) and Kochta (K, planifolia

and K. sedifolia), small shrubs which grow to a height of 12-36". Trees are

absent because of the comparative heavy texture of the surface soils.

The dominant shrubs vary greatly in their density of growth according to

species, associated soil and rainfall. In ungrazed stands of bladder saltbush

(Atriplex vesicaria) and low bluebush (Kochia planifolia) there may be as many

as 170 to 180 bushes on 2/33 acre (see quantative estimates). On the other hand,

stands of bluebush (Kochia sedifolic) may have a density as low as 20 to 25

bushes on 2/33 acre.

During drought times the ground between the shrubs is devoid of growth

but im good seasons may, depending upon the soil and also upon the density of

the shrubs, be almost completely covered with herbage and grass. Where the

growth of bush is very dense competition is so severe that even in good seasons

little herbage or grass appears between the bushes.

Arid woodland formation

Trees (Acacit spp.) form a woodland of variable density on the lighter

textured soils. and rormally vary from 20 to 50 yards apart. In previous litera-

ture the Acacia woodland country has been referred to as a scrub formation but

this term is misleading when applied to country in which trees are frequently

very scattered and there is a scarcity of undershrubs. Grasses, of which

Aristida spp. (A. arenaria and A. browniana) and Enneapogon spp. (E. poly-

phyllus and E, avenaceus) are most widespread, are most prominent in the ground

layer especially after summer rains, BSassia uniflora is common following winter

rains,

Shrub-orid woodland formation

This includes areas where an understorey of shrubs occtits beneath the trees.

The formation grades into the shrub-steppe formation on the one hand and the

arid woodland formation on the other according to the density of the trees and

shrubs.

Arid hill woodland formation

In previous literature the arid hill communities have been called scrubs but

are better regarded as woodlands. The formation is represented in the North-

West hy the community on the Denison Range.

231

Desert sclerophyllous grassland formation

The dominant species on the sandhills of the desert or near desert areas is

the sclerophyllons grass Zygochloe paradoxe (sandhill canegrass), Herbaceous

grasses are the principal associated species,

THE PALATABLITY OF TILE SPECIES

The plants occurring in the communities of the North-West have heen

assigned to five palatability groups: those with a palatability rating of | are very

palatable, 2 aré quite palatable, 3 are moderately palatable, 4 are slightly palatable

and 5 are unpalatable. The palatabilities were largely assessed from observations

of selectivity of grazing around watering pomts.

The palatability of any plant to stock depends upon a number of factors,

which are determined by both the grazing animal and the plant species, Palata-

hility ratings given here are the preferences of mature merino sheep, The most

important factors influencing ihe palatability of any plant species are its growth

stage and the plants with which it is associated. The growth stage is particularly

important in the case of species which produce spiny fruits, for example, the

Bassias, and which are therefore more palatable when young than when mature.

The palatability ratings given here are an average for the whole of the life cycle.

The importance of the coliection of plants available to the grazing animal is

illustrated by the fact that even some of the unpalatable species (palatability 5)

like Kochia pyramidcta are grazed under drought conditions when nothing else

is available, in fact under extreme conditions sheep will eat dry sticks and twigs.

Palatability ratings have been given to about 170 species. Shrubs and trees

with a palatability of 1 are few in number. Very palatable trees are not destroyed

by stock because a portion of their foliage is out of reach, but the very palatable

shrubs like Cassia sturtti’ and Eremaphila latrobei have been considerably depleted,

There are more very palatable herbaceous species (grasses being prominent) than

trees and shrubs and many of them, for example Erodiwns cygnorum, Clianthus

spectosus, Convolvulus erubescens, Trichinium exaltatum and Eragrostis dielsit

are suppressed by grazing. Others like Stipa nitida remain of common occurrence

because they are prolific seeders.

Again there are very few shrubs and trees with a palatability of 2, but this

group includes the widespread Kochia plenifolia and Atriplex vesicaria, species

which are destroyed by heavy stocking. Herbaceous species with a palatability

of 2, among which grasses are prominent, are also few in number and most of

them are suppressed in heavily grazed country. More plants oceur in group 3

than in either groups 1 or 2, atid herbaceous species are more tiumerous than

shrubs and trees. Moderately palatable species are not often suppressed except

under conditions of very heavy stocking.

Slightly palatable species (palatability 4) are not suppressed by grazing and

more plants fall into this group thant in either groups 1, 2, 3, or 5. The majority

of the shrubs and herbaceous species do not spread in heavily grazed country

but they do persist. There are exceptions however ltke the free-seeding Bassia

paradoxa and Atriplea halimoides which spread on certain soil types. Genera

represented by the largest number of slightly palatable species are Zygophyllum

with 2. crenatum, Z. anunophilum, Z. iodtocarpum, and Z. compressum and

Eremophila with E. scoparia, E. duttonit, E_ serrulata, E£. alternifolia, E, opposit-

folia and E. maculata,

Group 5 (plants of no yalue) contains about the same number of species as

group 3 but shrubs are more numerous than herbaceous species. Some of the

free-seeding species like Kochia triptera yar. ertoclada, K. pyramidata and Bassia

232

divaricafa spread where competition with more palatable species has been reduced

through grazing.

The palatability ratings of species of Bassia, Kochia, Atriplex, Acacia and

grasses occurring in the North-West are set out in Table XT,

THE PLANT ASSOCIATIONS

éicacia aneura — A. brachystachya association (“mulga country”).

The dominant species of this community are 4, aneura and A. brachystechya,

small trees which grow to a height of 16-24 feet, These species cannot be dis-

tinguished on vegetative characters alone. Although A. aneura most commonly

has one main trunk and 4. brachystachya two or three, ihe reverse is frequently

found, Black (1929) gives the length of the phyllodia in 4. axéwra as 3-7 centi-

metres but lengths of up to 10 centimetres are not uncommon, thus overlapping

the range for A, brachystachya which is 5-18 centimetres, However, the pods

of the two speciés are fairly easily distinguished and in August - September of

1946, when their distributions were determined by reconnaissance survey, the two

species were both fruiting prolifically. The community is found on sandy soils

of the Wirraminna type, calcareous Kon Bon soil and occasionally the heavier

textured calcareous Wilgena soil.

On the deepest sands mulgas fori a woodland of variable density (Plate XVIII,

Figure 4 and Plate XIX, Figure 1). They become more scattered on Bon Bon

soil and sparse (or more usually absent) on Wilgena soil. The understorey also

varies greatly, Where more than three feet of sand overlies lime rubble or hardpan

bladder saltbush and bluebush are both absent. Bladder saltbush appears where

two to three feet of sand overlies heavy lime, while bluebush will only grow

where less than two feet of sand overlies the lime. The mulga community there-

fore varies from a fairly dense woodland with a grass layer beneath the trees to

a shrub-woodland with scattered trees and an understorey of shrubs, All grada-

tions occur hetween these two extremes and because the surface sands were re-

distributed during the Recent the pattern is very complex.

The following are the chief floristic characteristics of the association on the

three soils;

1, Mulga on Wirraminna (sandy) soil

The mulgas usually form a fairly dense woodland. Bluebush is absent from

the deepest sands but forms an understorey where the surface sands are shallower,

Prior to stocking bladder saltbush was common, but the ecotype associated with

sandy soil is easily destroyed by grazing, so that little remains in stocked country.

The ground betwéen trees aid shrubs is dominated by mulga grass (Aristida

arénaria), black heads (Enneapogon polyphylius and FE. evenaceus) and bindyi

(Bassia unifiora), which form a complete ground cover in favourable years.

Danthonia bipartite and Eragrosits eriopoda are also prominent on sandridges

with the above herbaceous species. -

A wide variety of shrubs and herbaceous species are associated, the com-

monest of which are Kochia georgei (erect form), Australian boxthorn (Lycisen

australe), tornato bush (Enchylaena tomentosa), Sida virgata, firebush (Kochia

triplera var. erioclada), bundy bush (Cassia eremophila var. platypoda), cat tail

(Trichinium alopecuriodeum) and buck bush (Salsola kali), Of these species

XK. georgei, tomato bush, bundy bush and cat tail are of little value to the grazier.

Australian boxthorn, which sheds its leaves under drought conditions, and Sida

virgata are moderately palatable. Firebush is a free-seeding rapid growing

species which colonizes overgrazed country where competition with other species

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234

Taste XI Showing the palatabil

in species

ity ratings of certa

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235

has been reduced. It is unpalatable. Bundy bush colonizes sandy tmulga country

where the trees have been destroyed hy firing. Tomato bush is always found

beneath tree canopies,

2. Mulga on Bon Bon soil

The mulgas are more scattered and the herbaceous growth is sparser as the

sandy A horizons of the soils become shallower, Bluebush forms an understorey

beneath the trees. The only associated shrubs of common occurrence are bird’s-

eye Cassia (Cassia sturtit) and Acacia kempeana, Sida virgata and the small-

leafed iorm of Chenepoditm nitrariaceum are fairly common. Bladder saltbush

Was once common but has largely been destroyed by grazing.

The chief herbaceous species are bindyi (Bassia obliquicuspis), mulga grass

(Aristida arenaria), black heads (Enneapogon cylindricus, E. caerulescens,

E. palyphyllus and E, ovenaceus), while Bassia uniflora, B. sclerolaenoides,

geranium (Lrodinm cygnorum) and Zygophyllum prismatothecum are fairly

common, Of these species B. abliguicuspis, B, sclerolaenoides, Enneapogon

ewindrieas and EB, caerulescens are most prominent on the shallowest of the Bon

Bon soils, Where the surface sands are slightly deeper mulga grass, £. poly-

phyllus, BE, avenaceous and B. uniflora become the dominants.

Bird's-eye Cassia is very palatable and although it is still of common occur-

rence has been depleted through grazing. Acacia kRempeana and the small-ieafed

form of Chenopodium nttrariaceum are only slightly palatable.

In addition to the mulga association, Bon Bon soil also supports myall—

hluebush or occasionally bluebtish without trees (X. sedifelia association). Apart

from tree species the three associations are floristically similar when associated

with Bon Bon soil.

3. Mulga on Wilgena sail

When it supports 4. aneura—A. brachysiachya association Wilgena soil

carries very scattered mulgas and herbaceous species form a sparse growth, The

hiuebush understorey is often not as dense as it is on Bon Bon soil. Mulga asso-

ciation is actually rarely found on Wilgena soil, Where the mulga and myall-

bluebush association complex occurs the latter community is usually found on

Wilgena soil, while further north where myall is absent, that is, in the 4. onewra —

A. brachystachya—— K. sedifolia association complex country, Wilgena soil carries

treeless bluebush (K. sedtfolia association). Apart from tree species the com-

munities are floristically similar when associated with Wilgena soil.

The mulga community on Wilgena (and Bon Bon) soil contains fewer

species than it does on deep sandy (Wirraminna) soil. Apart from bluebush,

fairly common shrubs are sagebush (Trichinium obovatum), bird's-eye Cassia and

Kochia triptera var. pentaplera, Dominant herbaceous species are the bindyis

(Bassia obliguicuspis and B. sclerolaenoides) and black heads (Fnneapogon

c\lindricus), E. caerulescens and Zygophyllum prismatothecum are fairly com-

mon. Mistletoes (Loranthus exocarpi and |. murrayi) are common parasites on

the mulgas. A complete list of species found in the association, the soils on which

they grow and their palatabilities to stock are shown in Table XII.

Mulga death has been severe throughout the North-West. From numerous

counts which were made it is estimated that about one-third of the mature mulgas

have died on the sandy soils, while on the heavier-textured soils the proportion

of dead trees ts even greater. Mulga is very susceptible to death by firing,

Although the fires that occur are only “grass fires” they kill up to two-thirds of

thé mulgas and those that survive never recover completely and die earlier than

unburnt trees. On the other hand, regeneration is sometimes increased and there

256

may be up to half as many established mulga seedlings in the burned country as

there were mature trees prior to the fire,

Changes which have occurred with grazing

The frequency of occurrence of the species on Wirraminna Soil in the mulga

country of the Lake Wirrida block, which has never been stocked, was compared

with adjacent stocked areas. As the shrub growth on the deep sandy soils is

comparatively sparse, stocking would be expected to cause rapid changes in the

density and Horistic composition of the shrub component of the vegetation. This

is found to be the case,

Common shrubs on Wirraminna soil in ungrazed country are bluebush

(K. sedifolia), saltbush (4, vesicaria), Eremophila latrobei, bundy bush (Cassia

eremoplila var. platypoda), tomato bush (Anchylaena tomentosa) and Kochia

georgei (erect form). Sagebush (Trichinium obovatum), tar bush (Eremophila

glabra) and Sida virgata are fairly common.

In grazed country bundy bush and tomato bush are still common because

they are rarely grazed. The erect form of Kochia georgei is only slightly palatable

but js thinned out to some extent under heavy grazing. S. wrgata, which is

moderately palatable, remains, fairly common because of its free-seeding habit.

Bluebush is moderately palatable but is very hard to kill by grazing. The very

palatable Evemophila latrobei becomes of very rare occurrence in stocked country,

while sagebush and tar bush, which are moderately palatable, become fairly rare.

The ecotype of saltbush associated with sandy soils is rapidly destroyed by stock.

Australian boxthorn is protected from excessive grazing by its spines and

although moderately palatable has increased. There has been a marked increase

in the amount of the unpalatable firebush.

Dominant herbaceous species in ungrazed country are mulga grass (Aristida

arenaria), Enneapogow polyphyllus, E. avenaceus and Bassia uniflora and on

sandridges Danthonia bipartita and Eragrostis eriopoda, Although mulga grass

is only moderately palatable it is an excellent drought reserve. It is not grazed

to any extent when other herbaceous feed is available, but during drought times

the dry grass is completely eaten, It has the additional advantage of producing

new growth rapidly after a dry period following light rain and provides grazing

for stock before annual herbage appears. E. polyphyllus, E, avenaceus and

B. uniflora are much more palatable than mulga grass and are suppressed under

heavy stocking. The proportion of these species to mulga grass is the best indica-

tion of the stocking to which the country 1s subjected.

Mulga country as a grazing unit

It has been pointed out that ithe mulga community is most commonly asso-

ciated with sandy soils of the Wirraminna type and that shrubs are of sparse

occurrence on the deeper sands. As a consequence the bush drought reserve is

comparatively small. This can be readily seen by reference to the quantitative

map showing the present bush density of Commonwealth Hill Station (see fig. 12)

where there are large areas of mulga country not interspersed with other plant

associations. When this survey was carried out most of Commonwealth Hill

was virgin country, =~

However, the foliage and pods of the mulgas themselves are very palatable,

and although stock soon trim the foliage up to the height they can reach, dry leaves

are constantly shed from the trees: The dominant shrubs of the shrub-steppe

communities shed their leaves during drought times and live in a state of

anabinsis. The result is that the shrubs are a valuable reserve in the carly stages

of drought but if the dry period is prolonged they provide little more than sticks

237

for the stock to graze. The mulgas, however, continue to shed leaves from their

canopies, so that in a prolonged drought they are of much greater value as a

food reserve than shrubs.

After mulga country has been grazed for some time and an equilibrium

between stocking and vegetation has been reached, the most important species in

the community to the grazier are 4. arenaria, E. polyphyllus, E, avenaceus and

Bassia uniflora. Jt is not possible in practice to economically graze mulga country

and maintain the balance between stock and plants to enable the ecotype of salt-

bush found on sandy soils or the very palatable Eremophila latrobe: to be main-

tained except as very rare species.

Tasre XII

List of species found in the Acacia aneura— A. brachysiachya. association,

D = dominant, VC = very common, C = common, FC = fairly common,

FR = fairly rare, R = rare, VR = Very rare,

Frequency

Palat- Natural in grazed Associated soil

ability frequency coutitry

Acacia aneura- - - - Jf D D All three; rare on Wilgena

Acacia brachystachya = - - 1 D D All three; rare on Wilgena

Kochia sedifolia = - - e 4 vc VC Absent from deep sands

Stipa nitida - - - ee | FR FR Absent from deep sands

Enneapogon polyphyllus - 1 D D All three but most on Wirra.

Bassia uniflora - - - 1 D D All three but most on Wirra.

Bassia obliquicuspis - - 42 FR FC Absent from Wirraminna

Bassia paradoxa - - = ¢ VR R Bon Bon and shallow Wirra.

Aristida atenaria - - = D D All three but rare on Wilgena

Enchylaena tomentosa - - 4 FC KC All three

Rhagodia spinescens var. - 4 VR R All three

Kochia triptera var. erioclada- 4 VR FC All three, particularly Wirra-

minna; rare on Wilgena

Lyctum australe - - - 3 FR FC All three

Cassia eremophila yar. platypoda 4 FC FC Wirraminna only

Kochta georgei (erect form) - 4 Cc FC Wirramitina only

Salsola kali -~- - - ~ 2 FC FC All three

Enneapogon avenaceus - - 1 Cc Cc All three

Eroditm cygnorum = - | FR FR All three, particularly Bon Bon

Tetragonia expansa - - 1 R R Wirra. and Bon Bon

Tetragonia eremaea ~ = | zr RR Wirra, and Bon Bon

Tragus australianus - r 3 VR VR All three, partic. Wirraminna

Euphorbia drummondii - - 4 R R All three

Portulaca oleracea ~ - - 2 VR VR Wirra, and Bon Bon

Sida virgata - - - - 3 Cc FC All three, particularly Wirra.

Eremophila latrobet Se | FC VR All three, particularly Wirra.

Eremophila glabra ~ - - 3 FC VR Wirra. and Bon Bon

Eremophila scoparia - - 4 VR VR All three

Acacia burkittii - - - 5 VR VR Wirra. and Bon Bon

Kochia pyramidata - - - § VR R Wirra. and Bon Bon

Eucarya spicata ~ = - § FC VR All three

Heterodendron oleifolium - 1 VR VR Wirra, and Bon Bon

Eremophila paisleyi - - 4 R R

Grevillea nematophylla - - 4 R R Wirra. and Bon Bon

Pentatropis kempcana - - VR VR Wirra. and Bon Bon

238

Frequency .

Palat- Natural in grazed Associated soil

ability frequency country

Eremophila duttonii - - 4 VR VR Bon Bon and Wilgena

Eremophila longifolia - » 3 VR VR Wirra. and Bon Bon

Eremophila alternifclia

var. latifolia - - - 4 FR FR Wirra. and Bon Bon

Sida intricata - - - - 3 VR VR Bon Bon and Wilgena

Abutilon leucopetalum = - - § R R Wirra. only

Bassia divaricata - - - 5 VR VR Bon Bon and Wilgena

Solanum ellipticum - - - + VR VR All three

Goodenia spinescens ~+ ey “8 VR VR

Acacia kempeana - - | FR FR All three, partic, Bon Bon

Acacia oswaldii - - eal VR VR All three, partic, Bon Bon

Dodonaea microzyga - - 4 VR VR ~~ Bon Bon and Wilgena

Gumniopsis quadriida - - 42 VR VR Wirra, only

Sida petrophila - = - 4 VR VR All three

Cassia artemisioides - - 3 VR VR AML three

Zygophyllum fruticulesum

var. eremaeum- + ~- 4 FR FR All three

Chenopodium nitrariaceum 4 VR VR Bon Bon and Wilgena

(small-leafed form) - -

Bassia sclerolaenoides - - 3 FC FC Wilgena and Bon Bon

Cassia sturtii - - - - 1 FC FR Bon Bon and Wilgena

Templetonia egena- - - 4 VR VR sS Wirra. and Bon Bon

Fucarya acuminata- - - 2 VR VR AMI three

Kochia triptera var. pentaptera 5 FR FR Bon Bon and partic. Wilgena

Acacia tetragonophylla - - 4 FR FR All three, least on Wirra.

Kochia tomentosa - - - 95 VR VR Bon Bon and Wilgena

Dodonaea attenuata - = 4 VR VR sWirta. only

Eragrostis eriopoda - - 4 FC FC Deep sands only

Danthonia bipartita - = @ FC FC Deep sands only

Eremophila serrulata - - 4 VR VR AIL three

Trisetum pumillum - - -_ = VR VR

Phyllanthus lacunarius = - - 5 VR VR Wirra only

Chenopodium cristatum- - 4 VR VR Wirra only

Calandrinia remota-— - - 1 VR VR Wirra only

Cucumis mytiocarpus = - - 4 VR VR Wirra. and Bon Bon

Swainsona_ burkittii - - VR VR Wirra. only

Triraphis mollis - + - 3 R R Wirra. only

Clianthus speciosus s re Ob VR VR Wirra. and Bon Bon

Zygophyllum ammophilum - 4 VR VR sOAIL three

Euphorbia eremophila - - 3 R R Wirra only

Trichinium alopecuroideum - 4 FC FC Wirra only

Calotis cymbacantha - - 3 VR VR Wirra. and Bon Bon

Aristida anthoxanthoides - 3 VR VR

Lepidium papillosum = - = 4 VR VR All three

Lepidium oxytrichum = - - 4 VR VR All three

Goodenia’ cycloptera - - 4 FR FR Wirra and Bon Bon

Citrullus vulgaris - - - 65 VR VR Wirra and Bon Bon

Stenopetalum lineare - a VR VR All three

Convolvulus erubescens - - 1 VR VR Wirta, only

Angianthus pusillus - - 4 R R All three

Chenopodium desertorum - 383 R R Wirra, only

239

Frequency

Palat. Natural in grazed Associated sci]

ability frequency country

Myriocephalus stuartii - - VR VR Wirra.. only

Didiscus glaucifolius - 4 VR VR Wirra. only

Trichinium exaltatum - - R VR Wirra. and Bon Bon

Enneapogon caerulescens - FC FC Bon Bon and Wilgena

Enneapogon cylindricug - = - FC FC Ton Bon and Wilgena

FR FR Wirra, and Bon Bon

FR YVR All three

Helipterum floribundum - -

Rassia eriacantha - - 5

Loranthus exocarpi - - c c On mulgas (parasitic)

Loranthus murrayi = - “ Cc c On mulgas (parasitic)

Zygophyllum prismatothecum- FC FC All three

VR VR Wirra. and Bon Bon

VR VR Wirra. and Bon Hon

FR FR All three

VR VR All three

VR VR Wirra. and Bon Bon

VR VR

FR VR All three

VR VR Wirtra, only

Dactyloctenium radulans -

Tribulus terrestris - - -

Acacia anétira var. latifolia -

Atriplex spongiosa - - -

Nicotlana sp. - - - -

Craspedia pleiocephala - -

Atriplex quinii - . -

Trichinium obovatum - = -

Codonocarpus cotinifolius -

meno fe Nee owe | uw

Acacia sowdenii— Kochia sedifolia association (pl. xix, fiz. 3)

In this shrub-woodland community an understorey of bluebush is present

beneath an open woodland of small trees of A. sowdend (myall) which vary from

16-28 feet in height. Myall is the most attractive tree found in the arid country

of South Australia. Prior to being grazed by stock its branches and foliage sweep

to the ground (pl. xix, fig, 2) and the new foliage produced after heavy rains has

a silvery-grey colour, Death of myall has not been as severe as mulga and

amounts to only 15-20 per cent, of the mature trees,

A. Sowdenii has a curious distribution. Both the species itself and the myall-

bluebush association occur particularly on Bon Bon but also on Wilgena soils.

There are, however, large areas of these soils normally colonized by myall from

which it is absent, for example in the country to the north-west of Kingoonya

where the A aneura—A. brachystachya—— K. sedifolia association complex occurs,

Here species normally associated with myall occur but myall itself is lacking,

Rainfall is stightly lower than in most of the myall country, but the species does

occur in more arid ateas than this, for example, occasional myalls occur along

wadis and creeks as far north as the south branch of the Neales River and in

parts of the Denison Range.

The limited distribution of the species is ptobably the result of restricted

colonization, The recession of plant species in South Australia during the arid

Recent and their subsequent spread from centres of survival has been discussed

by Crocker and Wood (1947), who suggested that myall suryived in the Gawler

Ranges. There were also other minor stitvival centres such as along creeks like

the Neales “River” and in the Denison Range, The implication of the restricted

spread of myall following the lifting of climatic stress during the Recent is that

the period of ittcreased rainfall was of too short duration to enable the species

to migrate to all the areas it is capable of colonizing. The present rainfall is lower

than during the moist period of colonization,

The species occurring in the myall-bluebush association vary with the depth

of the sandy surface horizons of the soils, On the shallowest Bon Bon soils and

240

on Wilgena soil the herbaceous layer is dominated by black heads (Enneapogon

cylindricus) and bindyi (Bassia obliquicuspis), the latter increasing with depletion

through grazing of the bluebush cover. E. caerulescens and B. sclerolaenotdes are

prominent. On the deeper soils E. cylindricus and Bassia obliquicuspis are again

dominants, but B, sclerolagnoides and E. caerulescens are of rare occurrence.

E. polyphyllus, E. avenaceus, mulga grass and B. uniflora are very common,

B. paradoxa may become very common when the community suffers very heavy

grazing and bush death,

Bluebush is the dominant shrub but Cratystylis conocephala replaces it in

some of the southern myall country, Australian boxthorn (Lycium australe)

is fairly common, while Chenopodivm nitrariaceum (small-leafed form) and fire-

bush (Kochia triptera var. erioclada) are fairly rare, Complete floristics of the

association and the palatabilities of the species are given in Table xiii.

Changes which occur with grazing

The most noticeable effects of heavy grazing are an increase in the amount

of bindyi (Bassia obliquicuspis) and sometimes B. paradoxa. Black bluebush

(Kochia pyramidata) and. firebush may also spread. These species, with the

exception of B, obliquicuspis, ate of slight or no value. At the same time blue-

bush is depleted and Enneapogon polyphyllus, E. arenaceus and Bassia uniflora

are suppressed. Bird’s eye Cassia and bladder saltbush were more common prior

to grazing. Overgrazing and death of bluebush containing an admixture of

bladder saltbush may, on the sandier Bon Bon soils, result in a saltbush dominant

understorey because saltbush frequently seeds heavily prior to death.

The community as a grazing unit

The foliage of A. sowdenii is always grazed by stock to as high as they

can teach but its foliage is actually only slightly palatable, so that it is only under

drought conditions that any leaves which are shed are eaten by sheep. The

principal drought reserve of the myall-bluebush country is K. sedifolia. Apart

from bluebush the most important species in the community to the grazier are

black heads (Enneapogon polyphyllus, E. avettaceus and E. cylindricus), the

bindyis (Bassia uniflora and B. sclerolaenoides) and mulga grass (Aristida

arenaria).

Tan.e XIII, showing a complete list of species found in the

A. sowdenii —K, sedifolia association

Frequency

Species Palatability of occurrence

Acacia sowdenii ~ ye aah cel 's GY 4 -D

Kochia sedifolia - - - - - ms 3 D

Bassia obliquicuspis - - ¢ @ i t 3 vc

Lycium australe - - = = = 4 “ 3 FC

Chenopodium nitrariaceum - - = - > = 4 FR

Bassia paradoxa - - - = = ~ 4 ff FR

Kochia triptera var. erioclada - = ~ - - 5 FR

Enchylaena tomentosa- - - + - - 4 R

Rhagodia spimescens var. deltophylla - - - 4 R

Cassia tremophila var. platypoda- = ale gh R

Cassia sturtii - be E as : _ I R

Kochia pyramidata - - - - - 5 R

Eremophila scoparia - - - - at la R

Sida virgata- - - - - = 7." 3 R

Atriplex vesicaria - - - - = = 2 R

Bassia divaricata eee te dew ay “SS VR

Species

Eucarya acuminata - " =.

Eucarya spicata - - - -

Grevillea nematophylla i

Kochia triptera- - 4 a

Cassia eremophila - = -

Exocarpus aphylla - - -

Templetonia egena - - -

Eucarya persicarius - - -

Dodonaea microzyga - - -

Myoporum platycarpum - -

Eremophila duttonii - - -

Eremophila serrulata - - “

Heterodendron oleifolium - -

Acacia tetragonophylla - -

Eremophila rotundifolia - -

Eremophila alternifolia - -

Eremophila alternifolia var, latifolia

Acacia kempeana - - - -

Acacia oswaldii - - - -

Trichinium obovatum

Acacia burkittli = - - ~ -

Eremophila latrobei

Eremophila paisleyi

Sida intricata - - - -

Pittosporum phillyreoides - -

Eremophila longifolia - - -

Cassia artemisioides - - -

Zygophyllum fruticolosum

Kochia tomentosa - - -

Kochia triptera var. pentaptera -

‘

Enneapogon cylindricus - -

Aristida arenaria - - - -

Bassia uniflora - ~ - -

Ienneapogon polyphyllus - -

Enneapogon avenaceus - -

Zygophyllum prismatothecum -

Salsola kali - - - - -

Bassia sclerolaenoides - - -

Tetragonia expansa - - -

Tetragonia eremaea - - -

Erodium cygnorum - - -

Enneapogon caerulescens - -

Stipa nitida + - - - -

Euphorbia drummondii - -

Chenopodium desertorum - -

Eragrostis setifolia - - =

Goodenia, cycloptera

Tribulus terrestris - - -

Sida petrophila - - - -

Tragus australianus - - -

Triraphis mollis - - - -

Babbagia dipterocarpa - - -

‘

241

Palatability

MBWENENWREHE RPE ONMH HP BOHWUUAOUWNHUREMAUWUARAUEE RED A | aa | ae a)

Frequency

of occurrence

_ VR

242

Zygophyllum ammophilum - - + = - 4 VR

Craspedia pleiocephala- - - - - - 4 VR

Atriplex spongiosa -— ms co VR

Clianthus speciosus - - - + - - 1 VR

Zygophyllum compressum - - -~ - a: VR

Loranthus exocarpi ~ - = + = < 1 VR

Loranthus murrayi += = - - - - 1 VR

Kochia sedifolia association (Plate XIX, Figure 4)

Treeless shrub steppe areas dominated by bluebush are found on Bon Bon

and Wilgena soils beyond the range of myall, The floristics of the community

vary according to the soil.

1. K. sedifolia association on Wilgena soil

K. triptera var. pentaptera is a common associated shrub and sagebush

(Trichinium obovatum) is fairly common. Dead-finish (Acacia tetragonophylia)

is fairly rare. The dominant herbaceous species are bindyis (Bassia sclerolaen-

oides and B, obliquicuspis) and Enneapogon cylindricus, while E. cacrulescens,

buck bush (Salsola kali) and Bassia uniflora are fairly rare.

2. XK. sedifolia association on Bon Bon soil

Soapbush (Zygophyllum fruticulosum), sagebush (Trichintim obovatwmn)

and bird’s eye Cassia (Cassia sturtit) are fairly common associated shrubs-

Broombush (Eremophila. scoparia) is fairly rare, The dominant herbaceous

species are bindyi (Bassia obliquicuspis) and Enneapogon cylindricus, while

E. caerulescens, E. avenaceus, E. polyphyllus, Bassia sclerolaenotdes and buck bush

(Salsola kali) are fairly rare. Complete floristics of the association are given in

Table XIV,

Changes which occur with grazing

Heavy grazing of the community on both Wilgena and Bon Bon soils causes

depletion of bluebush, bladder saltbush and Cassia sturtit and increase in bindyi

(Bassia obliguicuspis). Sagebush (Trichinium obovatum) is depleted where the

community is on Wilgena soil, The grasses Ennegpogon polyphyllus and

E. avenaceus and the bindyi Bassia uniflora are also suppressed under heavy

grazing.

Taste XIV

showing complete Aoristics of the K. sedifolia association

Species Frequency on $Frequency on

Bon Bon soil Wilgena soil Palatability

Kochia sedifolia - - + - - D D 3

BRassia obliquicuspis < - - - - vc C 3

Zygophyllum fruticulosum- - - - FC VR 4

Trichiniuin oboyatum - - - - FC FC 8

Cassia sturtii - - - - - - FC VR 1

Eretnophila scoparia - - - - - FR VR 4

Lycium australe - * - = - R VR 3

Rhagodia spinescens var, deltophylla - VR VR 4

Enchylacna tomentosa ~ - - - VR VR 4

Cassia artemisioides - - - - - VR VR 3

Sida virgata - - - - - - VR VR 3

Chenopodium nitrariacetim - - - VR R 4

Sida corrugata - - - - - - VR VR 4

Sida intricata - - - - - - VR VR 3

243

Bppciee Tee oesed Wilgeas soil’ Palatability

Casuarina cristata - - - + - VR VR 4

Eremophila rotundifolia - - - - VR R 5

Kochia tomentasa - - - - - VR R 4

Kochia pyramidata - a VR _— 5

Eremophila duttonii - - - - - VR VR 4

Acacia oswaldii - - - - - - VR VR i

Acacia tetragonophylla - - - - VR FR 4

Dodonaea microzyga - - - - VR VR 4

Goodenia spinescens - - - - = VR — 5

Eremophila alternifolia - - - - VR VR 4

Eremophila alternifolia var. latifolia ~ VR as 4

Solanum ellipticum - - - - - VR VR 5

Bassia paradoxa - - - - - VR VR 4

Acacia _kempeana - - - - - VR VR 4

Eremophila latrobei - - - - - VR VR 1

Bassia divaricata - - - - - VR VR 5

Kochia triptera var. pentaptera - - VR Cc 5

Enneapogon cylindricus - - - - D D 3

Enneapogon caerulescens - - - - FR FR 3

Bassia sclerolaenoides “ - - - FR vc 3

Enneapogon avenaceus - - - - FR VR 1

Enneapogon polyphyllus - - - - FR VR 1

Salsola kali - - - - - - FR FR 2

Bassia uniflora - - - - - - R FR 1

Aristida arenaria . - - - - R VR 3

Atriplex vesicaria - - - - - VR VR 2

Kochia triptera var. erioclada - - - VR VR 5

Zygophyllum prismatothecum - - = VR R 5

Vittadinia triloba ~ - - - - VR _- 4

Stipa nitida - ~ - - - - R R |

Sida petrophila - - - - - - VR VR 4

Portulaca oleracea - - ~ - - VR — 2

Abutilon leucopetalum = - - = - VR — 5

Blennodia trisecta = - - - - - VR — —

Stenapetalum lineare - - - - VR VR —

Calotis cymbacantha - - - - VR —_ 3

Danthonia semiannularis - - - - VR _ 1

Lepidium oxytrichum - - - - VR VR 4

Lepidium papillosum - - - - VR VR 4

Helipterum floribundum - - - - VR — 5

Craspedia pleiocephala - - - - VR —_— 4

Zygophyllum iodiocarpum - - - VR — 4

Erodium cygnorum - - - - - VR VR 1

Goodenia cycloptera - - a - - VR —_ 4

Bassia eriacantha - - - - - — VR 2

Santalum ianceolatum - - - - VR VR 1

Euphorbia drummondii = - - - - VR VR 4

Acacia linophylla — A. ramulosa association (Plate XX, Figure 1)

These two species, which grow to a height of 9-14 feet, are the dominants

on the sandhills in the southern portion of the North-West. Black oak (Casuarina

244

cristata) is of common occurrence with the acacias on the sandhills south of the

east-west railway line, North of the railway line black oak is of rare occurrence

on the dunes but pine (Callitris glauca) partly or completely replaces the acacias

on some of the sandhills (pl, xx, fig. 2). Shrub species, with the exception of

Cassia eremophila var. platypoda which is very common on Roxby Downs Station,

are of rare occurrence in the community. Aristida browntana is the dominant

herbaccous species. Commonly associated with it are Plagiosefum refractum,

Enneapogon polyphyllus, E. avenaceus, Salsola kali and Atriplex vellutinellum.,

Triraphis mollis ts fairly common. The following species are common after

winter rains: parakeelya (Calandrima remota), Blennodia canescens, Stuart's

daisy (Myriocephalus stuartii), Angianthus pusillus, Calotis cymbacantha and

Helichrysum semifertile,

Practically all of the dunes in the southern sandhill country carry this stable

climax community, but some of the dunes superimposed upon the tableland and

immediately surrounding it are unstable. Primary colonizers of these unstable

dunes are Salsola kali, Atriplex velutinellum, Crotalaria dissitiflora and Myrio-

cephalus stwartii. The first shrubs to appear are sandhill wattle (Acacia hgulote)

and hop bush (Dodonaea atienuata).

Complete floristics of the association are given in Table XV.

The sandhills as a grazing unit.

The dominant acacias have unpalatable foliage and shrubs ate practically

absent, so the sandhill country is of little value in drought times. Further, the

dominant herbaceous species (Aristida browniana) is a coarsé unpalatable grass.

The community is most valuable to the grazier following winter rains when a

dense growth of ephemeral species is produced. However, if the preceding

summer rains have been heavy the growth of grass, particularly 4. browniana, is

frequently so dense as to allow little space for annual species.

TABLE XV

showing complete floristics of the Acacia linophylla—A. ramulosa association.

PRN Palatabitity sree

Acacia linophylla - - - - 4 D

Acacia ramulosa - - - - 4 D

Casuaring cristata - = > 4 Cc

Callittis glauca - + - = 5 Cc

Cassia eremophila var. platypoda - 4 FC

Acacia ligulata - - “ - 5 VR

Heterodendron oleifolium - - 1 R

Dodonaea attenuata - - - 4 VR

Abutilon Jeucopetalum - = - 5 R

Eucarya spicata - - - - 4 VR

Duboisia hopwoodii - - - 5 VR

Eremophila paisleyi - - - 4 R

Pittosporum phillyreoides - - 2 VR

Kochia triptera - - - - os R

Enchylaena tomentosa - - = - 4 R

Hakea Jeucoptera ~ - - - 5 VR

Sida intricata - - - - 3 VR

Greyillea nematophylla - - - 4 R

Myoporum montanum - = oo VR

Phyllanthus fuernrohri - = ie: 5 R

245

Speciea Frequency of

Palatability occurrence

Cassia sturtii - - - - 1 VR

Phyllanthus lacunarits - - - 5 FR

Bassia uniflora a 1 R

Eucalyptus pyriformis - - - 5 VR

Bossiaea walkeri - - - = - 5 VR

Aristida browniana Ses - 4 B

Plagiosctum refractum - - - 3 Cc

Enneapogon polyphyllus - - 1 Cc

Enneapogon avenaceus - - - 1 C

Salsola kali - . - + - 2 Cc

Atriplex velutinellum - - = 5 Cc

Triraphis mollis = - - - - 3 FC

Stipa nitida - - - - - 1 R

Citrullus vulgaris - - - - 5 R

Cucumis myriocarpus + - - 4 R

Didiscus glaucifolius = - - os — R

Aristida arenaria = - - - 3 FR

Euphorbia drummondii - - 4 R

Euphorbia eremophila - - - 3 VR

Lepidium oxytrichum ~« . - 4 VR

Lepidium papillosum - - - 4 VR

Zygophyllum iodocarpum - ~ - 4 R

Crotalaria dissitiflora - - = 4 VR

Convolvulus erubescens - - 1 R

Clianthus speciosus - = - 1 VR

Calandrinia remota - - - 1 FC

Biennodia canescens - - - 2 FC

Myriocephalus stuartii - - - 5 FC

Angianthus pusillus - - - 4 FC

Calotis cymbacantha - = < 3 FC

Helichrysum semifertile - - _— FC

Tetragonia expansa c = ~ 1 R

Tetragonia eremaea - - - 1 R

Trisetum pumillum - - - — VR

Nicotiana sp. Sr 5 VR

Goodenia cycloptera = - - 4 R

Zygophyllum ammophilum - = 4 R

Stenopetalum lineare - - - — VR

Atriplex spongiosa - - . 4 R

Zygochloa paradoxa association (Plate XX, Figure 3)

Sandhills in the Lake Eyre region are completely covered with scattered

plants of sandhill canegrass (Zygochloa paradowxa formerly Spinifex paradoxus),

a sclerophyllous grass which is more akin to the hard-leaved shrubs than the

usual soft-leaved herbaceous grasses. It has a palatability rating of 4, In the

adjacent Simpson Desert the crests of the dunes are bare (Crocker, 1946).

Herbaceous growth is always much sparser than on the Acacia spp. sandhills

further south,

Shrub species which commonly occur with the canegrass are sandhill wattle

(Acacia ligulata) and hop bush (Dodonaea attenuata), while Trichinium obova-

tum and Phyllanthus fuernrohrti are fairly common. Common hetbaceous species

are caltrop (Tribulus terrestris), Aristida browniana and Crotalaria dissitifiora,

246

while. the following are fairly common: mulga grass, bur grass (Tragus austra-

lianus), buck bush, Plagiosetum refractum, Myriocephalus stuartii and Euphorbia

drummondii, Complete floristics are given in Table XVI.

The sandy flats between the dunes carry a modified mulga community.

Spinifex (Triodia basedowii), which is the dominant species between the dunes

in the Simpson Desert (Crocker, 1946), is absent. The mulgas are very scattered.

Hop bush, sandhill wattle, Eremophila duttonii and needlebush (Hakea leucop-

tera) are the most common shrubs, Canegrass sometimes extends onto the flats

where the sands are very deep. Mulga grass is the dominant herbaceous species

on the sandy flats. Typical associated species are Enneapogon polyphyllus,

E. avenaceus, Citrullus vulgaris, Cucumis myriocarpus, Abutilon leucopetalum,

Euphorbia drummondii, Crotalaria dissitiflora and button grass (Dactyloctenium

radulans ).

Taste XVI

showing the species present in the Zygochloa paradoxa association

Frequency of

Species occurrence

Zygochloa paradoxa - - = - = = D

Acacia ligulata - - - - - e . Cc

Dodonaea attenuata - - ~~ ~ - Cc

Trichinium obovatum - - - = - = FC

Phyllanthus fuernrohrii - mere tS FC

Eremophila sp. - - - - - - = FR

Acacia aneura - = 7, am x @ - VR

Acacia brachystachya -~ ef > e & VR

Sida virgata - - < = * = t VR

Sida petrophila - - - - - - = VR

Gumniopsis quadrifida - - - - - = VR

Aristida browniana J w= - > “mle Cc

Crotalaria dissitilora - - - - - - Cc

Aristida arenaria’ - - - - - - = FC

Tragus australianus - - - - - = FC

Salsola kali - - - = - ss Fin £ FC

Plagiosetum refractum - - - - - FC

Myriocarpus stuartii - - - - - - FC

Euphorbia drummondii > re st «2 = FC

Phyllanthus lacunarius - - - - - FR

Triraphis mollis - - - = - é a FR

Portulaca oleracea - - ed tt FR

Enneapogon polyphyllus - - - =~ & FR

Enneapogon avyenaceus B sde male me ge FR

Cucumis myriocarpus - - - mi ~ ~ FR

Atriplex spongiosa - - - - - - R

Abutilon leucopetalum - » - - - R

‘Trianthema crystallina var. clavata - - - VR

Trichodesma zeylanicum var. sericeum - + VR

Nicotiana sp. - eos = = = = VR

Eragrostis eriopoda - - -“ = = - VR

Zygophyllum howittii - - - 3S Pe oA VR

Aristida anthoxanthoides - - - - —- VR

Citrullus vulgaris a VR

Tetragonia spp. - - - 3 £ ‘ : VR

247

Eremophila freelingi— Acacia aneura—A. brachystachya association.

The Denison Range south of Oodnadatta supports a hill-woodland com-

munity dominated by E. freelingit and mulgas (Acacia aneura and A. brachy-

stachya).

Acacia aneura—A. brachystachya —A. tetragonophylla association

(Plate XX, Figure 4)

These species are the dominants of the association found in watercourses

and “swamps” on transported soils in the Mount Eba depression. Shrubs are

generally not conspicuous, the community being an arid woodland. Prickly

acacia (Acacia victoriae) and Sida virgata are fairly rare, while Trichinium

obovatum, Eremophila rotundifolia, Bassia divaricata and cotton bush (Kochia

aphylia) are rare.

The dominant herbaceous species are mulga grass (Aristida arenaria) and

bindyi (Bassia paradoxa), while button grass (Dactyloctenium radulans) and

B. uniflora are fairly rare. Salsola kali, Eragrostis falcata, Enneapogon poly-

phyllus and E. avenaceus are rare. Complete floristics are given in Table XVII.

TaBLe XVII

showing the species present in the 4. aneura—A. brachystachya—

A, tetragonophylla association,

Species Palatability ee

Acacia aneura - - - - 1, D

Acacia brachystachya - - - 1 D

Acacia tetragonophylla_ - - - 4 D

Bassia paradoxa = - . - - 4 Cc

Bassia uniflora - - - - 1 FR

Acacia victoriae - - - - 3 FR

Sida virgata - - - - - 3 FR

Trichinium obovatum - - - 3 R

Eremophila rotundifolia - - - 5 R

Bassia divaricata - - - - 5 R

Kochia aphylla - - - - 4 R

Cassia sturtii - - - - ~ 1 VR

Kochia pyramidata ” - - 5 VR

Eremophila paisleyi - = - 4 VR

Zygophyllum fruticulosum - - 4 VR

Santalum lanceolatum - - - 1 VR

Eremophila longifolia - - - 3 VR

Pittesporum phillyreoides - - 2 VR

Exocarpus aphylla . - = 4 VR

Eremophila duttonii - - - 4 VR

Rhagodia spinescens - - - 4 VR

Sida intricata - - - = - 3 VR

Bassia eriacantha - - - - 2 VR

Eremophila serrulata - - - 4 VR

Cassia artemisioides - - - 3 VR

Cassia desolata - - - - 4 VR

Cassia phyllodinea - - - - 4 VR

Heterodendron oleifolitum - - 1 VR

Acacia oswaldii - - - - 3 VR

Eremophila scoparia - - - 4 VR

Eremophila maculata - ~ - 4 VR

248

Species Palatability ia stg

Bassia patenticuspis - - - 2 VR

Enchylaena tomentosa - - - 4 VR

Solanum ellipticum . ~ - 5 VR

Bassia sclerolaenoides - - - 3 VR

Atriplex vesicaria - - - - 2 VR

Kochia lobiflora - - - - _— VR

Aristida arenaria - - - - 3 D

Dactyloctenium radulans - - 2 FR

Salsola kali + - - - - 2 R

Eragrostis falcata - - ~ - 3 R

Enneapogon avenaceus - - - 1 R

Enneapogon polyphyllus - - 1 R

Sida petrophila - - - - 4 VR

Stenopetalum lineare - - - _— VR

Zygophyllum ammophilum = - - 4 VR

Abutilon Ieucopetalum - -— = 5 VR

Zygophyllum compressum “ - 4 VR

Stipa nitida - - - - - 1 VR

Lepidium papillosum - ~ - 4 VR

Blennodia trisecta - - - - — VR

Teucrium racemosum = - - - 3 VR

Helichrysum cassinianum - - —_ VR

Erodium. cygnorum - - - 1 VR

Minuria leptophylla - - - 4 VR

Eragrostis setifolia - - - 2 VR

Marsilia drummondii - - - 4 VR

Rhagodia nutans = - - - - 3 VR

Goodenia cycloptera - - - 4 VR

Phyllanthus lacunarius - - - 5 VR

Eragrostis dielsii - - - = 1 VR

Atriplex spongiosa - - . 4 VR

Citrullus vulgaris - - - - 5 VR

Aristida anthoxanthoides - - 3 VR

Portulaca oleracea - - - - 2 VR

Cucumis myriocarpus - - ~ 4 VR

Euphorbia drummondii - - - 4 VR

Tetragonia expansa - - - 1 VR

Tetragonia eremaea - - - 1 VR

Convolvulus erubescens - - - 1 VR

Tribulus terrestris - - - - 2 VR

Enneapogon cylindricus - - 3 VR

Clianthus speciosus - - - 1 VR

Eulalia fulva - - ~ - 1 VR

Ixiolaena leptolepis - - - 4 VR

Helipterum floribundum - - 5 VR

Kochia planifolia — Bassia spp. association (Plate XXI, Figure 1).

This shrub steppe community is also found on transported soils in the Mount

Eba depression but on slightly more elevated sites than the Acacia aneura—

A. brachystachya—A. tetragonophylla association. It is associated with low

terraces between watercourses. Kochia planifolia is always of sparse occurrence

on Mount Eba soil. Because of this low natural density of low bluebush grazing

249

causes rapid destruction of the bush cover. Further, fairly heavy bush death

occurs on this soil under drought conditions even when stocking is light.

The association is generally devoid of trees but scattered mulga (Acacia

aneura and A. brachystachya) and dead finish (4. tetragonophylia) may be

present. In addition to low bluebush, Bassia paradoxa and B, divaricata are very

common species. Dominant herbaceous species are Bassta eriacantha, B, uniflora

and mulga grass. Complete floristics are given in Table XVIII.

Small crabholes are a common feature of the country and here, in addition

to species mentioned above, the following occur: cotton bush (Kechia aphylla)

is a dominant shrub, while Jxtolaena leptolepis is very common and Atriplex

vesicaria is common. Eremophila maculata is fairly common. Eragrostis falcata

is a common grass in the crabholes.

Changes which occur with grazing:

The 4. aneura—A. brachystachya—A. tetragonophylla and Kachia plani-

folia— Bassia spp. associations form an, association complex and are best discussed

together. Heavy grazing results in increase in the amount of Bassta paradoxa

and B. divaricata, while B. uniflora and B. ertacantha are suppressed. Low

bluebush and bladder saltbush are depleted under grazing. The free-seeding

rapid growing prickly acacia (A. victoriae) has spread in the watercourses during

the last few years.

The association complex as a growing unit:

Due to the common occurrence of clay very near the soil surface the her-

baceous cover is fairly patchy, even in good seasons, During drought years much

of the country is completely devoid of plant growth. However, the community

occurs in low lying sites and is particularly valuable to the grazier in good scasons.

The principal drought resetve is now mulga, low bluebush having practically all

been destroyed through grazing. Many of the most common shrubs are of little

or no value. Most important species in the pasture are Bassta uniflora, Acacia

victoriae, Sida virgata, mulga grass, button grass and Bassia eriacantha.

TasLe XVIII

showing the species found in the K, planifolia - Bassia spp. association.

Frequency of

Species Palatability occurrence

Kochia planifolia - - - - 2

Bassia eriacantha - - - -

Bassia paradoxa - - - -

Bassia divaricata - - - .

Bassia tiniflora - - - -

Acacia aneura - - - -

Acacia brachystachya - -

Acacia tetragonophylla_ - - -

Atriplex quinii ~ ~ ~ -

‘Trichinium obovatum - - -

Bassia brachyptera - - -

Eremophiia rotundifolia ~ - -

Eremophila diuttonii < ~ 4

Atriplex vesicaria - - - -

Cassia sturtii - - - - -

Kochia pyramidata - - - -

Sida virgata - - - - -

Pittosporum phillyreoides - -

NwWUe who & On bee Re on bh

“4d nner mt TtAwWrAooDoOY

aa wa

250

Frequency of

Species Palatability occtirrence

Cassia eremophila - - - - 4 VR

Kochia triptera var. pentaptera - 5 VR

Bassia obliquicuspis ~ = = 3 VR

Sida intricata - - - - 3 VR

Cassia artemisioides - - - 3 VR

Acacia oswaldii - - - ~ 3 VR

Enchylaena tomentosa - - - 4 VR

Bassia tricuspis - - - - 5 VR

Exocarpus aphylla, - - - 4 VR

Eremophila alternifolia - - - 4 VR

Solanum ellipticum - - - § VR

Eremophila paisleyi - - - 4 VR

Ixiolaena leptolepis - - - 4 VR

Bassia lanicuspis - - - - 3 VR

Cassia desolata - = = = 4 VR

Cassia phyllodinea - - - - 4 VR

Eremophila latrobei - - - 1 VR

Dodonaea microzyga - - - 4 VR

Aristida arenaria - - - - 3 D

Salsola kali - - - - ~ 2 FR

Enneapogon. polyphyllus - - 1 R

Enneapogon avenaceus - - -' 1 R

Angianthus pusillus - - + 4 VR

Stenopetalum lineare - - - — VR

Portulaca oleracea - - - - 2 VR

Nicotiana sp. - - - - - 5 VR

Zygophyllum ammophilum = - - 4 VR

Lepidium oxytrichum - - - 4 VR

Stipa nitida - - - - - 1 VR

Babbagia dipterocarpa - - - 5 VR

Lepidium papiflosum 4 - - 4 VR

Blennodia trisecta - - - ~ 5 VR

Helichrysum cassinianum - - — VR

Erodium cygnorum - - - - 1 VR

Goodenia cycloptera - - - 4 VR

Panicum decompositum - - - 3 VR

Dactyloctenium radulans - | - - 2 VR

Euphorbia drummondii - - = 4 VR

Tribulus terrestris - - * - 2 VR

Enneapogon cylindricus - - - 3 VR

Clianthus speciosus - - - - 1 VR

Eulalia fulva - - - - - 1 VR

Helipterum floribundum - - - 5 VR

Euphorbia eremophila - - - 3 VR

Astrebla pectinata - - . - 3 VR

Tragus australianus - - - 3 VR

Kochia aphylla - - - - 4 D

Eremophila maculata ~ - - 4 FR

Bassia echinopsila - - - - — VR

Bassia yentricosa = - - - 3 VR

Eragrostis falcata - - - - 3 Cc

Rhagodia nutans - - - - 3 VR

Chloris acicularis - - > - 3 VR

251

Kochi planifolia association. .

This shrub steppe community is associated with Twins soil. Low bluebush

is the dominant species but bladder saltbush is of common occurrence. These

species may be uniformly distributed (Plate XXI, Figure 2) but over wide areas

growth is restricted to slight depressions where the soil is an inch or two deeper

and where the moisture status is somewhat higher (Plate XXI, Figure 3).

Sagebush (Trichinium obovatum) and Atzoon zygophylloides are shrubs of

fairly common occurrence, while broombush (Eremophila scaporia) and native

pittosporum (Pittosporum phillyreoides) are fairly rare. The principal herba-

ceous plants in the community are buck bush (Salsola kali), button grass (Dacty-

loctenium radulans) and Aristida anthoxanthoides. Fairly common are Ennea-

pogon cylindricus and Trianthema crystalline var. clavata, Complete floristics are

given in Table XIX.

The community as a grazing unit.

The K. planifolia association has a lower carrying capacity than any other

community in the North-West. The density of low bluebush and bladder salt-

bush is generally fairly low even where the community is well preserved. Further,

the poor water-rctaining capacity of the soil has resulted in widespread bush death

under drought conditions, with the result that living bush is restricted to water-

courses and slopes of undulations over much of the country, Due to its greater

regeneration capacity there is a tendency for bladder saltbush to become the

dominant species in place of low bluebush.

During most seasons the growth of herbage and grass is. extremely sparse,

large areas where shale is exposed being devoid of growth.

TABLE XIX

showing the species present in the K. planifolia association.

. Frequency of

Species Palatability occurrence

Kochia planifolia - - = - 2 D

Atriplex vesicaria - - - - 2 vc

Aizoon zygophylloides - - - 5 FC

Trichinium obovatum = - - - 3 FC

Pittosporum phillyreoides - - 2 FR

Eremophila scoparia - - - 4 FR

Acacia tetragonophylla - - - 4 R

Kochia tomentosa - - - - 4 VR

Rhagodia spinescens var. deltophylla 4 VR

Solanum ellipticum - - - - 5 VE

Sida corrugata - - - - 4 VR

Eremophila rotundifolia - - - 5 VR

Eremophila oppositifolia - - 4 VR

Atriplex quinii - - es 5 VR

Bassia patenticuspis - - - + 2 VR

Acacia oswaldii - - ~ - 3 VR

Bassia divaricata - - - - 5 VR

Kochia aphylla - - - - 4 VR

Kochia pyratnidata - - - - 5 VR

Bassia eriacantha - - - - 2 VR

Bassia Jaticuspis - - - - 3 VR

Bassia biflora - - - + - — VR

Heterodendron oleifolium - = 1 VR

Santalutn lanceolatum = - - - 1 VR

252

Frequency of

Species Palatability occurrence

Enchylaena tomentosa —- - - 4 VR

Bassia obliqnicuspis - - = 3 VR

Bassia uniflora - - - - 1 VR

Bassia paradoxa - - - - 4 VR

Kochia triptera yar. pentaptera - 5 VR

Arthrocnemum sp, - - - - 5 VR

Kochia eriantha - - - - 1 VR

Chenopodium nitrariaceum (small

leafed form) - - + = 4 VR

Sida virgata - - - - - 3 VR

Bassia sclerolaenoides - - - 3 VR

Lycium australe - - - - 3 VR

Eremophila alternifolia - - - 4 VR

Cassia sturtii - - - - - 1 VR

Zygophyllum apiculatum - - 5 VR

Eremophila longifolia - - - 3 VR

Zygophyllum fruticulosum - - 4 VR

Salsola kali - - - = - 2 Cc

Dactyloctenium radulans - - 2 Cc

Aristida anthoxanthoides - - 3 Cc

Enneapogon cylindricus - - - 3 FC

Trianthema crystallina var. clavata — FC

Chloris acicularis - - - - 3 FR

Aristida arenatia - ~ - - 3 R

Portulaca oleracea - - - - 2 R

Enneapogon avenaceus - - 1 R

Enneapogon polyphyllus- - = - T R

Tribulus terrestris - - - - 2 VR

Lotus australis var. parviflorus - 4 VR

Zygophyllum prismatothecum - 5 VR

Tetragonia eremaea - - - 1 VR

Stipa nitida - - - - - 1 VR

Euphorbia drummondii - - 4 VR

Convolvulus eruhescens - - - 1 VR

Euphorbia eremophila. - - - 3 VR

Tragus australianus - - - 3 VR

Sporobolus actinocladus - - - 1 VR

Panicum decompositum - - - 3 VR

Babbagia dipterocarpa - - - 5 VR

Zygophyllum ammophilum~— - - 4 VR

Erodium cygnorum - - - 1 VR

Bassia brachyptera - - - - 4 VR

Chloris truncata - - - - 3 VR

Sida petrophila - - - - 4 VR

Trichinium erubescens - - . —_ VR

Atriplex vesicaria — Kochia planifolia association (Plate XXI, Figure 4).

This shrub steppe community is associated with Coondambo soil. The

dominant species are bladder saltbush and low bluebush. Scattered trees of mulga

(Acacia aneura), umbrella mulga (A, brachystachya) or myall (A. sowdentt)

are occasionally present. Coondambo soil is characterised by light-textured

A horizons overlying clay at shallow depth. However, watercourses which drain

253

Coondambo soil areas frequently have deeper sandy A horizons overlying the

clay. On these soils little K. planifolia is associated with bladder saltbush,

Star bush (Gummniopsis quadrifida) is a common associated shrub, while

Bassia. ventricosa, B. decurrens, broombush (Eremophila scoparia) and Sida

virgata are fairly rare. The dominant herbaceous species are Ennecapogon poly-

phyllus, E, avenaceus, Bassia uniflora and mulga grass (Aristida arenaria), while

button grass (Dactyloctentum radulans) and nevertail (Eragrostis dielsii) are

fairly common, Complete floristics are given in Table XX.

The community as a grazing unit:

The A. vesicaria—K, planifolia association has a greater stock carrying

capacity than any other plant community found in the North-West. Bladder

saltbush and low bluebush are both palatable species and constitute an excellent

drought reserve. In this association they form a very dense bush stand in

ungrazed areas and competition for moisture is so severe that even in favourable

seasons little herbage and grass appears among the bushes. Some thinning of

bush is necessary to efable herbage and grass to appear in the community and

thus increase its grazing value.

Gumniopsis quadrifida is the most impottant associated shrub to the grazier-

All of the common herbaceous plants are very valuable species.

Changes which occur with grazing:

Bladder saltbush and low bluebush are both grazed to about the same extent

but saltbush is not as resistant to grazing as bluebush, so that heavy grazing

results in alteration of the proportion of saltbush to bluebush in favour of blue-

bush. However, saltbush is a more prolific seeder and regenerates much more

readily than bluebush, so that spelling or reduced stocking of country which has

been heavily grazed restores the original proportion of saltbush and bluebush.

Under heavy grazing the herbaceous species Enneapogon folyphyllus, E.

avenaceus, Bassia uniflora and Eragrostis dielsti are suppressed, All these species

are quite palatable and together with button grass and mulga grass constitute the

principal pasturage. Bassia paradoxa, which is of little value, colonizes sand

mounds where scalding has occurred. On the exposed clay of the scalded areas

Bassia divaricate, B. ventricosa and B, obliquicuspis are common.

TABLE XX

showing the species present in the A. vesicaria—K. planifolia association.

Frequency of

Species Palatability occurrence

Atriplex vesicaria - - - - ie D

Kochia planifolia - - - - 2 D

Gumniopsis qdtiadrifida - - - 2 Cc

Bassia uniflora - - - - 1 Cc

Bassia ventticosa - 3 - - 3 FR

Sida virgata - - - - - 3 FR

Eremophila scoparia ~ - - 4 FR

Bassia decurrens - - - - 3 FR

Bassia lanicuspis - - - - 3 VR

Kochia tomentosa var. appressa = - 4 VR

Kochia pyramidata - - - - 5 VR

Bassia paradoxa - - - 4 VR

Kochia aphylla - - - - 4 VR

Cassia sturtii - - - - - 1 VR

Eremophilg duttonii - - - 4 VR

Bassia obliquicuspts - - - 3 VR

Bassia divariceata - - - - 5 YR

Species

Kochia triptera var. erioclada

Kochia ciliata - - “

Heterodendron oleifolium

Acacia burkittit - -

Goodenia spinescens -

Solanum ellipticum - -

Dodonaea microzyga -

Eremophila alternifolia -

Acacia tetragonophylla -

Pittosporum phillyreoides

254

Kochia triptera var. pentaptcra

Eremophila longifolia -

Sida intricata - - -

Sida corrugata - - -

Trichinium obovatum

Cassia phyllodinea -

Euphorbia eremophila

Enneapogon polyphyllus

Enneapogon avenaceus ~~

Aristida arenaria - -

Dactyloctenium radulans

Eragrostis diclsii - -

Tragus australianus -

Salsola kali - - -

Portulaca oleracea - -

Atriplex spongiosa - “

Erodium cygnorum -

Euphorbia drummondii -

Triraphis mollis - -

Zygophyllum crenatum -

Convolvulus erubescens -

Zygophylium ammophilum

Zygophyllum compressum

Tribulus terrestris - -

Lepidium papillosum -

Enneapogon cylindricus -

Tetragonia eremea - -

Enneapogon caerulescens

Trianthema crystallina var. clavata

Chenopodium cristatum -

Stipa nitida ~~ - -

Stenopetalum lineare “

Lotus australis var. parviflorus

Craspedia pleiocephala -

Helipterum floribundum -

Clianthus speciosus - -

Atriplex halimoides var, condupli-

catum - - -

Citrullug vulgaris - -

Bassia brachyptera - -

Babbagia dipterocarpa -

Angianthus pusillus -

Bassia sclerolaenoides -

Brachycome iberidifolia var. glan-

dulifera - - -

Palatability

the ax! | tee ae | Lag hh teb oa KS Ps gs pera ltes ge Aga Bor a Es a RO MGarih ee a ecg ee Eacerr ha dep pee eaceacae! | ery

w te on dm on te

Frequency of

occurrence

255

Atriplex vesicaria — Bassia spp. association (Plate XXII, Figure 1),

This shrub steppe community, whose occurrence at Yudnapinna station has

previously been described by Crocker and Skewes (1941), is associated with

Coober Pedy soil. Growth ts practically restricted to the crabholes’ where they

are present, while elsewhere a sparse growth occurs over the country as a whole.

A. vesicaria and Bassia spp. are the dominant shrubs. Of the Bassas,

B. ventricosa is common while B. paradoxa and B, tricuspis are fairly rare.

B, divaricate and B. lanicuspis are rare. In addition to these cotton bush (Kochia

aphylia) and low bluebush (.K. plantfolia) are of fairly rare occurrence. Domin-

ant herbaceous species are Eragrostis falcata, button grass (Dactyloctenium

radulans), Enneapogon polyphyillus, and E. avenaceus. Mitchell grass (Astrebla

pectinata) is common, while the following are fairly common: Aristida anthox-

anthoides, pop saltbush (Atriplex spongiosa), sugar grass (Eulalia fulvua) and

Bassia brachyptera.

Changes which occur with grazing:

Even in ungrazed areas the density of bladder saltbush is low on Coober

Pedy soil, so that under drought conditions the bush that is present is subjected

to heavy grazing, Little saltbush therefore remains in most of the stocked pad-

docks. If, however, the country is spelled while sufficient seed-producing plants

remain, regeneration during favourable years is fairly rapid as the ecotype of

saltbush associated with these clay soils isa prolific seeder and a vigorous plant.

Bindyis, particularly Bassia paradoxa and B. divaricata, but also B. ventricosa,

increase under heavy grazing, Annual species like pop saltbush (Aériplex

spongiosa) also spread, At the same time the black head grasses (Enneapogon

polyphyllus and E. avenaceus) become thinned out,

Taste XXI

showing the species present in the .4. vesicaria— Bassia spp. association.

Frequency of

Species Palatability occurrence

Atriplex vesicaria - - - =

Bassia ventricosa - - - -

Bassia paradoxa - - - -

Bassia tricuspis - - - -

Bassia divaricata - - - -

Bassia lanicuspis - - - -

Kochia aphylla - - - =

Kochia planifolia = - - - -

Atriplex quinii - - - +

Sida intricata - = - - -

Txiolaena leptolepis - - “

Sida vitgata - - . -

Minuria denticulata - - - -

Trichinium obovatum - - -

Kochia pyramidata - - -

Baéssia eriacantha - - - -

Bassia tricornis - - + -

Eragrostis falcata - - - -

Dactyloctenium radulans - -

Enneapogon polyphyllus - -

Enneapogon avenaceus - - -

Astrebla pectinata - - - >

weer | NH&wb OPW on ty S&S Win ule wo

¥R

256

Frequency of

Species Palatability occurrence

Aristida. anthoxanthoides - - 3 Cc

Atriplex spongiosa - - - “ 4 Cc

Eulalia fulva - - - - - 1 Cc

Bassia brachyptera - - - = 4 Cc

Bassia uniflora - - - - 1 FR

Salsola kali - - - - - 2 FR

Portulaca oleracea - - - - 2 FR

Trianthema crystallina var. clavata — FR

Panicum decompositum - - - 3 FR

Aristida arenaria - - - - 3 R

Minuria leptophylla ~ - - 4 R

Sida corrugata var. trichopoda - 4 VR

Lotus australis var. parviflorus - 4 VR

Convoalvulus erubescens - - 1 VR

Euphorbia drummondii - - - 4 VR

Tragus australianus - - - 3 VR

Babbagia dipterocarpa - - - 5 VR

Sporobolus actinocladus - - - 1 VR

Enneapogon cylindricus - - - 3 VR

Erodium cygnorum - - - I VR

iseilema vaginiflorum - -~— - 2 VR

Goodenia cycloptera - - = 4 VR

Frankenia serpyllifolia - - - 5 VR

Rhagodia nutans - - -— - 3 VR

Zygophyllum ammophilum = - - 4 VR

Tetragonia eremaea - - - I VR

Atriplex halimoides var. condupli-

catum = = = -= = 4 VR

Cucumis myriocarpus - - - 4 VR

Citrullus yulgaris - - - ~ - 5 VR

Epaltes cunninghamii - - - — VR

Marsilia drummondii - - - 4 VR

Chloris acicularis - - - - 3 VR

Atriplex vesicoria —Ixiolaena leptolepts association (Plate XXII, Figure 2).

This community is found on Arcoona soil in the tableland country west of

Lake Torrens. Murray (1931) has described the vegetation of a portion of the

tablelands and called the community the “saltbush association”. It is advisable,

however, to retain the name Atriplex vesicaria association for the saltbush

dominant community found in north-eastern South Australia, where saltbush

occurs almost to the exclusion of other tree or shrub species (Wood 1937).

Murray (1931) includes bluebush (Kochia sedifolia) and black bluebush

(K. pyramidata) in the tableland vegetation. These species are constituents of

other plant associations and are never present in the A. vesicaria—I. leptolepus

association of the tableland proper.

The habitat is a gently rolling plateau characterised by the complete absence

of trees and tall shrubs except along creeks. Most of the vegetation does: not

exceed a height of 18”. There are really two habitats, the crabholes where most

of the vegetation is found and the more arid and saline shelves which are prac-

tically devoid of growth.

The dominant species are 4. vesicaria and I. leptolepis. Minuria leptophylla

is usually associated. Common shrubs and under-shrubs are samphires (.4rthrac-

257

nemum Isiostachywm and Pachycorma tenuis) and Psoralea sp. while Minuria

denticulata, Side corrugata var. trichopoda, Abutilon halophilum, Bassie ventri-

cosa, Atriples halimoides and A. halimoides var. conduplicatum are fairly com-

mon. The most prominent herbaceous species are the grasses Eragrostis setifolta

and £. faleate. Very common are mitchell grass (Astrebla pectineta), Panicum

decompositum, ray grass (Sporobelus actinocladus) and Lots australis var.

parviflorus, while Paspalidium sp., Swainsona stipularis, Bassie brachyptera,

Erodium cygnorum, Eulalia fulva, Atriplex spongiosa, Helipterum strictum and

Goodenia cycloptera are faitly common,

The gibber-covered shelves. between the crabholes are either devoid of plant

growth or carry a very scattered growth of Bassia ventricosa and B. brachyptera.

Less common on the shelves are Arthrocnemen leiostachyum, Pachycornia tenuis,

B, divaricata and Kockia tomentosa var. appressa, while B. sclerolaenoides and

K, eviantha ate very rarely present.

In addition to the species listed above for the tableland, there are other plants

which are only associated with creeks, The following small trees and shrubs are

typical of tableland creeks: Acacia brachystechya, A. aneura, A, tetrogonophylla,

A, rigens, A, oswaldii, Eremophila alternifolia, E,. serrulata, E, duttonti,

E, oppositifolia, E. globre, Pittosporum phillyreoides, Santalum lonceolatum,

Hakea teucoptera, Dodonaea fobulata, Prostonthera striatiflora, Cassia sturtit,

Heterodendron oleifolium and Casuarina cristata, Commonly occurring smaller

shrubs and undershrubs are Lnchylaecna tomentosa, Rhagodia spinescens, Kochia

aphylla, K, spongiocarpa, Atriplex vesicaria, Sida virgata, S. petrophila and more

tarely K, plantfolia and Bassia limbata,

Herbaceous. plants typical of creek beds are Aristida nitidula, Isotoma

petracu, Morgania glabra, Trichinium erubescens, Cucumis myriocarpus, Citrullus

wulgaris, Eragrostis australasica and rarely Psoralea patens, Helipterum fori-

bundum, Bassia wniflora, Aristida anthoxanthoides, Orobanche australtana,

Thysanotus bauert and Abutilon leucopetalum,

Following the exceptionally heavy rains of 1946 and 1947 Coolymilka Lake,

which is a depression in tableland country, contained about 20 feet of water at

its deepest part. By October 1947 the water level had fallen about five feet.

Near the waterline Erythraca australis, Epaltes cunninghamit, Calotis hispidula,

Atriplex spongiosa, Trigonella suavissima and Heliotropium curessavicum were

recorded, The lake is fringed by ti-trees (Melaleuca pubescens and M. pauperi-

olia),

f Tn addition to the normal crabholes of the tableland some large depressions

occur which are best regarded as swamps. Canegrass (Eragrostis australasica)

is usually the dominant species, but occasionally Chenopodium nitrariaceum and

Muehlenbeckia cumninghamts occur as dominants, Associated species are Calotis

hispidula, Trigonella suavissima, Teucrium racemosum, Erythraea australis,

Ranunculus parviflorus and nardoo ( Marsilia drummondi), Around the fringes

of these swamps especies typical of the 4, vesicaria—T, leptolepis association are

found.

The community as a grazing unit:

The tableland country has a fairly low stock-carrying capacity because much

of the area is occupied hy gibber-covered shelves largely devoid of plant growth-

However, the presence of crabholes into which water drains from the surround-

ing shelf areas ensures some grazing for stock after most rains. An outstanding

feature of the wool from sheep grazing on tableland country is its cleanliness.

This is due to the mantle of gibbers on the soil surface.

With the exception of A. vesicerta most of the common and fairly common

shrub spec's we only slightly palatable. Bladder saltbush is therefore the prin-

258

cipal drought reserve. Grasses (Eragrostis setifolia, E. falcata, Sporobolus

actinocladus, Eulalia fulva, Astrebla pectinata and Panicum decompositum) are

the most valuable members of the community to the grazier.

Changes which occur with grazing:

With intensive grazing of the crabhole vegetation the bindyis Bassia dtvart-

cata, B. ventricosa, B. paradoxa and B. tricuspis spread. Apart ftom B. ventricosa

these species are of little or no value. Competition with other plants in ungrazed

and lightly grazed crabholes restricts the bindyis principally to the crabhole fringes

and the arid shelves. Heavy grazing also causes an increase in annual or un-

palatable species like Atriplex spongiosa, Trianthema crystalline and the poisonous

Lotus australis var. parviflorus, A. vesicaria tends to be replaced by the less

palatable and less drought resistant A, Aalimoides and A. halimoides var. con-

duplicatum.

Taste XXII

showing the species occurring in the A. vesicaria —I. leptolepis association,

Natural Frequency in

Species Palatability frequency grazed country

Atriplex vesicaria - = - = - 2 D D

Ixtolaena leptolepis - - - - - 4 D D

Minuria leptophyla - - - - - 4 Cc VC

Pachycornia tenuis - - - - - 4 Cc Cc

Arthrocnemyum leiostachyum - - = 4 Cc Cc

Psoralea sp. - - - - - - - 3 Cc os

Minuria denticulata - - - - - 4 FC FC

Sida corrugata var. trichopoda - - - 4 Cc Cc

Abutilon halophilum - - - - - 4 FC FC

Atriplex halimoides - - - -~ = 4 R FC

Atriplex halimoides var. conduplicatum - 4 R FC

Bassia divaricata - - - - - 5 R FR

Bassia ventricosa - - - - . 3 FR FC

Bassia tricuspis - - - - - - 5 VR FR

Bassia paradoxa - - - - - 4 R FR

Acacia rigens - - - - . 4 R R

Kochia aphylla - - - - - 4 R R

Bassia btrachyptera - - - - - 4 FC FC

Kochia georgei (low form) - - - - 2 VR VR

Kochia planifolia - - - - - 2 VR VR

Kochia spongiocarpa - - - - - — VR VR

Kochia ciliata - - - - - - — VR VR

Kochia tomentosa var. appressa - - - 4 VR VR

Bassia biflora - < - - - - — VR VR

Bassia lanicuspis - - - - - - 3 VR VR

Sida intricata - - - - - - 3 VR R

Sida corrugata - - - - - - 4 VR VR

Atriplex fissivalve - - - - - = VR VR

Sarcostemma australe - - - - - 5 VR VR

Kochia eriantha - - - - - - I VR VR

Eragrostis falcata - - - - - 3 Vc VC

Eragrostis setifolia - - + - - 2 vc VC

Astrebla pectinata - - - - - 3 vc VC

Panicum decompositum - - - - 3 VC vc

Sporobolus actinocladus - - - - 1 VC veo

Lotus australis var: parviflorus - - - 4: Cc vc

259

Natural Frequency ip

Species Palatability frequency grazed country

Paspalidium sp. - - - + - - FC FC

Swainsona stipularis - - - - - FC FC

Erodium cygnorum - - - - - FC FC

Eulalia fulva - - - = = + FC FC

Helipterum strictum - - = - - FC FC

Goodenia pinnatisecta - - - - FC FC

Trianthema crystallina ~- - - - R- FR

Dactyloctenium radulans = - - - - FR FR

Atriplex spongiosa ~ - - - - FR FC

Eragrostis australasica - - - - FR FR

Trigonella suavissima - - - - FR FR

Eriochloa longiflora - - - - - FR FR

Euphorbia eremophila (leafless form) - FR FR

Calotis hispidula - - - - - “ FR FR

Plantago varia - - - - - - FR FR

Stipa nitida - = - - - - -

Babbagia dipterocarpa - - - - -

Enneapogon avenaceus - - * -

Daucus glochidiatus - - - = - -

Aristida anthoxanthoides - - + -

Mesembryanthemum aequilaterale - -

Frankenia serpyllifolia | - - - -

Teucrium racemosum - - - - -

Ranunculus parviflorus - - - ~

Marsilia drummondii - - - - -

Marsilia hirsuta ~ - - - - -

Chloris truncata - - - - - -

Helipterum floribundum = - - - -

Epaltes cunninghamii - - - - -

Eragrostis dielsii - - - - - -

Lepidium oxytrichum - - - = -

Zygophyllum fruticulosum var. eremaeum

Zygophylum ammophilum - - - -

Zygophyllum compressum - - - -

Tetragonia eremaeca - - - - -

Erythraea australis - - - - -

Bassia unifora - - - - - -

Tragus australianus = - - - - -

Portulaca oleracea - - - - -

Bassia sclerolaenoides- - - - - VR VR

Jrichinium erubescens - - - - VR VR

Anacampseros australiana - - - - VR VR

Tseilema vaginiflorum - - - - - VR VR

Atriplex rhagodioides association (Plate XXII, Figure 3).

On the Arcoona soils of the tableland cotintry west of Lake Eyre a shrub

steppe association dominated by silver saltbush (Atriplex rhagodioides) is found.

This community is floristically similar to the A. vestcaria—I. leptolepis associa-

tion which occurs on similar soils further south, but a few of the southern species

are absent. Most of the growth is restricted to the crabholes,

Chenopods are prominent among the shrubs. Common species associated

with A, rhagodioides are flat-topped saltbush (A. halimoides and A. halimoides

260

var, conduplicatum) and Bassia ventricosa, while Abutilon halophilum, Sida

corrugata var. trichopoda, cotton bush (Kochia aphylla) and Ixiolaena leptolepis

are fairly common, The most prominent herbaceous species are grasses of which

Eragrostis falcata, E. setifolia, flinders grass (Jseilema vaginiflorum), mitchell

grass (Astrebla pectinata), Aristida anthoxanthoides and ray grass (Sporobolus

actinocladus) are most common, Fairly common are Panicum decompositum,

Bassia brachyptera, pop. saltbush (Atriplex spongiosa), Threlkeldia proceriflora,

sugar grass (Eulalia fulva) and Swainsona stipularis.

There are several interesting differences between this association found in

the northern tableland country and that occurring west of Lake Torrens. Atriplex

rhagodioides replaces A. vesicarig as the dominant species and Iviolaena leptolepis

is not as common as it is further south, Samphires (Arthrocnemum leiostachyum

and Pachycornia tenuis) are of less frequent occurrence, but Kochia aphylla is

much more conspicuous. The common grasses are the same in both associations

except that flinders grass (Jseilema vaginiflorwm) is much more common in the

Lake Eyre region than further south. Canegtass (Eragrostis australasica), which

is present in the crabholes of the southern tableland country and which gives a

characteristic facies to the vegetation, is not present in the crabholes further north,

The community as a. grazing unit:

The A. rhagodiodes association has a very low stock-carrying capacity.

Apart from the absence of growth on the shelves between the crabholes, areas of

highly gypseous soils totally devoid of plant growth are common and the rainfall

of the habitat is the lowest recorded in Australia.

A. rhagodioides is unpalatable, so that Bassia species do not invade heavily

grazed crabholes as they do in the A. vesicoria—J. leptolepis association.

TaBLe XXII

showing the species present in Atriplex rhagodioides association.

Frequency of

Species occurrence

Atriplex rhagodioides - - . - ~J D

Atriplex halimoides - - a = “ Cc

Atriplex halimoides ‘var. conduplicatum - Cc

Bassia ventricosa et T'S fe A Cc

Abutilon haliphiluym - - - - - FC

Sida corrugata var. trichopoda - = - - FC

Kochia aphylla - - - = = - FC

Ixiolaena leptolepis ee FC

Arthrocnemum leiostachyum - - ~ FR

Pachycortia tenuis a FR

Bassia divaricata - - - - = = FR

Atriplex vesicaria - - - - = = R

Bassia paradoxa - - - - - = R

Minuria leptophytla be +” ae am = R

Kochia eriantha - - - - - = VR

Eragrostis falcata - - - - - - vc

Eragrostis setifolia - = + - « VC

Iseilema vaginiflorum - - - - = VC

Astrebla pectinata- - - - - - vc

Aristida anthoxanthoides - - - = - VC

Sporobolus actinocladus - + = ~ VC

Panicum decompositum. - = = - FC

Bassia brachyptera - - s s = FC

Atriplex spongiosa ~ = = = = Fc

261

Frequency of —

Species occurrence

Threlkeldia proceriflora - - - - FC

Eulalia fulya a - + - FC

Swainsona stipularis - - - - - FC.

Enneapogon polyphyllus - = = =! R

Enneapogon ayenaceus - - - - - R

Euphorbia drummondii - - - - R

Marsilia drummondii - - - - ~ : R

Salsola kali - - - - - - - R

Dactyloctenium radulans - -- - - R

Portulaca oleracea - - - - - VR

Trianthema crystallina var. clayata - - VR

Chloris acicularis - =- - - - VR

Babbagia dipterocarpa - - - - - VR

Tragus australiaznus - - - - - VR

Goodenia cycloptera = - - - - - VR

Calotis hispidula - - - - - - VR

Erodium cygnorum “ ~_ = «4 ra VR

Trigonella suavissima - - - + - VR

Paspalidium sp. - - - - = = VR

Daucus glochidiatus - - - - - VR

Aristida arenaria - - ~ - - - VR

Lotus australis var. parviflorus - - - VR

Atriplex quinii - - - - - - VR

Frankenia serpyllifolia - - - - - VR

Bassia lanicuspis - - - - - - VR

Bassia uniflora = - - - - - - VR

Sarcostemma australe - - - - - VR

Lepidium oxytrichum - - - - - VR

Kocha planifolia— Atriplex vesicaria—K. sedifolia association.

K. planifolia is a species which grows upon soils with a clay subsoil at

shallow depth, while K. sedifolia is associated with soils containing heavy lime.

Both heavy textured and calcareous soils are suitable for the growth of-A. vest-

caria. As a consequence these three species are the codominants of a shrub

steppe community on the heavy textured calcareous Miller’s Creek soil.

Very few shrubs are associated with the dominants, the following being the

only ones recorded: Trichinium obovatum, Kochia tomentosa, Sida corrugata

and very rare Acacia oswaldii, Heterodendron oleifolium and Sida. virgata,

The principal herbaceous species are bindyis (Bassia obliquicuspis and

B. sclerolaenoides), Enneapagon cylindricus, Zygophyllum prismatothecwm and

Salsola. kali. Of rare occurrence are Z. glaucescens, E. caerulescens, Goodenia

cycloptera, Erodium cygnorum, Tribulus terrestris and Convolvulus erubescens,

while the following are very rare: Euphorbia drummondii, Bassia untflora,

Citrullus vulgaris, Cucumis myriocarpus, Enneapogon avenaceus and E. paly-

phyllus.

The community as a grazing unit:

Severe bush death has occurred through grazing and droughts on the Miller’s

Creek soil even among the very hardy K. sedifolia, with the resiilt that there is

now little drought reserve, Further, even in good seasons the growth of herbage

and grass is very sparse, so the community has a very low stock-carrying capacity.

The plant communities associated with swamps, watercourses and creeks.

262

Mulga Swamps

Small depressions liable to inundation following heavy rains are a feature

of the mulga and myall woodlands. A well-defined drainage pattern is lacking, the

“swamps” being merely the result of very local drainage. They are characterized

typically hy a dense thicket of mulgas (4. anewra and A. aneura var. latifolia)

and umbrella mulga (4. brachystachya). Chenopodium nitrariacewm commonly

forms an understorey with nardoo (Marsilia drummondi) as a ground layer.

Lignum (Muchlenbeckia cunninghamit) is found occasionally, Epaltes cunning-

hamit and Eragrostis falcata are not as prominent as nardoo in the ground layer

but are usually present. Chenopodium nitrariaceum replaces mulgas im the centre

ot swamps which have a larger water intake.

Many species are found around the fringes of the swamps where the mulgas

are less dense. Sometimes broombush (Melaleuce wneinata) or ti-tree (M7.

pubescens) form a ring around the miilga thicket. The following shrubs are of

general occurrence aratutnd the fringes: Australian boxthorn (Lyctwm australe),

dead finish (Acacia tetragonophylia), Bassia paradexa, tomato bush ( Enchylaena

tomentosa) and Rhagodia spinescens. More rarely Ixiolaena leptalepis, Kochia

triptera var. erioclada, K. triptera var. pentaptera, Sida intricata and B. obligut-

cuspis are found.

Very rarely broombush (Eremophila scoparia), Santalum lanceolatum, 8.

dtvaricata, B, tricuspis, bullock bush (Heteradendron oleifolium), Cassia artemi-

stoides, Trichinium obovatum, Acacia hgwlota, A, oswaldii, Kochia planifolia,

K. pyramidata, Atriplex vesicaria, Grevillea nematophylia, Eucarya acuminata,

Zygophyllum. glaucescens, Z. fruticolosum, Acacia burktttii, Eremophila serrulata,

E. alternifolia and Side virgata are found.

The three herbaceous species characteristically found in the centre of swamps

are Marsilia drummondii, Epaltes cunninghamti and Eragrostis falcata, Com-

posites are very common in the area surrounding the centre of the swamps where

the following plants were recorded: Euphorbia drummondii, Eragrostis dielsii,

Calotis hispidula, Tetragonia expansa, T. eremaea, Atriplex spongiosa, Brachy-

tome iberidifolia var, glandulifera, Dactyloctenivm radulans, Calotis cymba-

canthe, Chenopodium cristatum, Goodenia subintegra, Craspedia pleiocephala,

Helichrysum cassinianum, Stipa nitida, Aristida arenaria, Lepidium papillosum,

L. oxytrichum, Gnephosis cyathopappa, Teucrium racemosum, Rutidosis helickry-

soides, Brachycome ciliaris var, lanuginosa, Gnaphalium luteo-album, Helipterum

semifertile and H, strictum, .

Of rarer occurrence are Stenopetalum lineare, Convolvulus erubesceus, Tri-

raphis mollis, Lotus australis var. parviflorus, Salsola kali, Erodium cygnorum,

Euphorbia eremophila, Enneapogon avenaceus, E, polyphyllus, Cucumis myrio-

carpus, Erythraea australis, Rhagodia nutans, Aristida anthoxanthoides, Emex

australis, Bassia uniflora, B. scleroloenoides, Blennodia canescens, Danthonia

semiammilaris, Vittadinia triloba, Clianthus speciosus, Portulaca. oleraceo, Stipa

eremophila and Chenopodium murale,

Melaleuca spp, swamps.

Some of the larger swamps carry broombush (Melaleuca uncinata) and

ti-tree (MW. pubescens) ag the dominant species. In other cases M. wncinata is

found throughout the centre of the swamp surrounded by a ring of M, pubescens

or the reverse may occur. These swamps generally have a larver water intake

than the mulga swamps, being fed by well-defined watercourses, Ti-tree indicates

more saline soi] conditions due to intake of more saline waters than broombush,

As a result the two species are a useful surface indication of the quality of the

ground water, better stock water being obtained by boring in broomibush rather

263

than ti-tree swamps, On Ingomar station the red sandridges around the claypans

carry M. wheinata, Bamboo Swamp on Billa Kalina station, which is a large

claypan carrying some canegrass, is fringed by M_ sncinata.

Atnpiex nuwmmularia (old mon saltbush) swamps.

The only 4. nummularia swamp in the sheep country of the North-West is

on Miller's Creek station in a small depression in tableland country (fig. 2).

A. nwmmularia is found on saline soils of floodplains and along some of the creek

channels in the vicinity of Coward Springs, The principal associated species are

nitre bush (Nétraria schoberi) and samphire (Arthrocnemum sp.).

Canegrass (Eragrostis australasica) swamps.

The largest swamps are characterised by the absence of mulgas and Mela-

leuca spp. except in the fringes. There ere three zones in the vegetation. In the

centre, that is in the area most frequently flooded, canegrass ts the dominant

species. Arotind the canegrass is a zone dominated by Chenapodium nitrariaceum,

while mulgas and a number of shrub and small tree species occur around the

margins.

The only shrubs associated with canegrass in the centre of the swamps are

lignum (Muehlenbeckia cunninghamii) and Chenopodium nitrariaceum, The fol-

lowing herbaceous species form 4 sparse ground cover: Teucrium racemosum,

Aristida anthoxanthoides, neverfail (Eragrostis dtelsit), nardoo (Morstha dram-

mondii), button grass (Dactylectenium radulans), pop saltbush (Atriplex spon-

giosa), bur grass (Tragus australianus), munyerao (Portulaca oleracea) and

Trianthema erystallina var. clavate. Native clover (Trigonella suavissima) grows

in a few of the swamps.

Apart from the dominant species the most characteristic plants of the

Chenopodium nitrariaceum zone are Eragrostis falcata and Teucrium racemosum.

Associated herbaceous species are the same as those found in the fringes,

Around the margins of the swamps scattered Chenopodium mifrariacenm

occurs with a variety of small trees and shrubs. The most characteristic of these

are mulgas (Acacia aneura, A. anenra var. latifolia and A. brachystachya), dead

finish (4, tetragonophylla), prickly acacia (A, victorige), button bush (Kechie

ephyila}, and tar bush (Eremophila glabra). Occasional native plum trees (Jan-

talum lanceolatum), broombush (Melaleuca uncimata), Muehlenbeckta exnning-

hamii, Grevillea nemataphylla and Sida intricata are also present. Herbaceous

species are Eragrostis falcata, Teucrium racemosum, Aristida arenaria, A, anthox-

anthoides, Salsola kali, Bassia obliquicuspis, B, lanicuspis, Dactyloctentum radu-

lens, Euphorbia drummondii, Trianthema crystallina var. clavata, Portulaca

oleracea, Atriplex elachophyllum and Morgania glabra, Frankemta serpyllifolia

is found around the margins of the more saline swatnps.

Smaller watercourses and creeks m shrub steppe areas.

The watercourses and smaller creeks which run through Twins and Coober

Pedy soil areas are lined by mulga (Acacta anéura) and umbrella mulga

(A. brachystachya) and a number of shrub species, some of which are absent

from the surrounding country. Commonly occurring shrah and small tree species

are dead finish (Acacia tetragonophylia), native pittosporum (Pitiosporum

bhillyreoides) and saltbush (Atriplex wesicaria), Associated with these are

Eremophila scoparia, E. duttonit, E. longifolia, Atriplex quinii, Kochia planifolia,

K, pyvamidata, Enchylaeno tomentosa, Rhagodia spinescens var. deltophylla, San-

talum lanceolatum, Lycium australe, Trichinium obovalum, Heterodendron olet-

folium, Sida intricata, Solanum ellipticum, Acacia wictoriag, A. oswaldii, Cassia

ertemisioides, Abutilon lencopeialum, Bassia paradoxa and B. divericata. Some

of the crecks carry Ewealyptus ofeosa (Plate XXII, Figure 4).

264

Herbaceous species are Enneapogon polyphyllus, E. avenaceus, Dacty-

loctentum radulans, Eulalia fulva, Chloris acicularis, C, trancata, Bassia patenti-

cuspis, B. tanicuspis, B, obliqnicuspts, B, uniflora, Zygophyllum ammophilum,

Paspalidium gracile, Eragrostis falcata, E. dielsi, Convoloulus erubescens, Aristida

arenaria, A, anthoxanthoides, Euphorbia drummondit, Tetragonia eremaga, T.

expanse, Tragus australionus, Tranthema crystallina var. clavate, Cucumis mvyrio-

carpus, Cilrullus vulgaris, Goodenia eycloptera, Rhagodia nutans, Themedd

avenacea and Chenopodium cristatum,

Larger watercourses and crecks in shrub steppe areas.

The larger creeks consist of one or two main channels with occasional long

narrow waterholes, but where they flood out they assume more the characteristics

of watercourses and consist of numerous interlacing channels with a few water-

holes (Plate XXIII, Figure 1). The main channels and waterholes are fringed by

coolibah trees (Eucalyptus coolabak)—Plate XXIII, Figure 2—and sometimes

inulga (Acacia ancura and A, brachysteciya). In and between the channels the

characteristic shrub species are canégrass (Eragrostis uustralasica), cotton bush

(Kochia aphylla), lignum (Muehlenbeckia cunninghamii) and Bassia bicornis.

The following are comparatively rare: Iriolaena leptolepis, Santalum lanceolatum,

fTakea iexcoplera, Eremophila glabra, Acacia victorioe, dead finish (4. tetragono-

phylla) and Minwria leptophylla, Rarely creeks are found carrying Broughton

willows (dcacia salicina) and A, stenophylla.

Associated common herbaceous species are Eragrostis falcata, Murray lily

(Crinum pedunculatum), pop saltbush (Airipler spongiosa) and Portulaca

oleracea, Of rarer occurrence are Dactyloctenium radulans, Chloris acicularis,

nardoo (Marsilia drummondit), Epaltes cunninghanui, Teucrium racemosumt,

Frankenia serpyltifolia, Bassia divaricata, B. ventricosa, Enneapogon polyphyllus,

Aristida anthoxanthoides, Cucumis myriocarpus, Citrullus vulgaris, Chenopodium

cristatum, Morgania glabra, Eragrostis dielsii, Luvatera plebeja, Astrebla pec-

tinata, Plantago veria, Erodium cygnorum, Calotis hispidula, Iseilema vagini-

florum, Euphorbia drummondii, Paspalidium gracile and Goodenia cycloptera,

Creeks of the northern tableland country,

The tableland country west of Lake Eyre is drained by a large number of

creeks which have their origin in tableland “ranges”, that is, in high tableland

areas or among residual hills, In addition some of the creeks, like the Douglas and

Umbum, rise in the Denison Range south of Qodnadatta, that is among hills con-

sisting of Precambrian rocks.

Numbers of small crecks originating near the western margin of the table-

land link up as they progress in an easterly direction and form very large creeks

the most important of which are The Neales, Peake, Matgaret and Warrinec

creeks and the Macumba creek which more or less separates the tableland country

from the sandy Simpson Desert. The creek beds are sandy or stony in their

upper reaches and clayey in the flood plains around Lake Eyre. Unlike the creeks

which reach Lake Eyre on its eastern side, those draining the tableland on the

western side of the Lake frequently discharge water into it after heavy rains.

Red gums (Eucalyptus camaldylensis) fringe the main creek beds in their

upper reaches where the soils are sandy and stony. Here the soil moisture is

less saline and the moisture-status is considerably higher than further down the

creeks because water flows in their upper reaches after rains which are not suffi-

cient to cause a general flow. Apart from an occurrence on Elizabeth and

Pernatty creeks red gums are restricted to creeks in the far north, the most

southerly gums being on Anna and Evelyn creeks. Red gums are restricted to the

265

main ereek beds, the subsidiary creeks carrying mulgas (Acacia aneura and

A, brachystachya), Eremophila freelingi and A, gilesiana in the western portion

and E. freelingit and gidgea (Acecta combaget) in the eastern portion of the

North-West.

Red gums are confined to the upper reaches of the creeks, Further down

they ¢earry coolibah (Eucalyptns coolabeh) with mulga in the western portion

and gidgéa in the eastern portion of the North-West. The most southerly gidgea

ereek is the so-called Mulga Creek south of Coward Springs. This is an isolated

occurrence, the nearest gidgea being om Douglas Creek about 60 miles north of

Mulga Creek. Along the north-south railway line the most southerly gidgea

creek ig north of Edward’s Creek railway siding. In the western portion of the

North-West gidgea is not found far south of The Neales, while its mast westerly

occurrence ts at Gypsum Bore ahout 50 miles west of Oodnadatta. Throughout

the area where gidgea and coolibah occur on the creeks the main channels carry

more covlibeh than pidgea, while subsidiary creeks carry gidgea alone: (pl. xxii,

fig. 3), South of the gidgea country the creeks are fringed by coolibah either

alone or with mulga. The most southerly coolibah is on Millet’s and Birthday

Creeks.

Associated shtubs and small trees are Acdcid stenophylla, lignum (Muchlen-

beckia cunninghamti) prickly acacia (4, victoriag), A. salicina, A, letragono-

phylla, Rhegodia spinescens var. deltophylla, Grevillea nematophylla, Dadonaea

attenuata, Cassia sturtit, Solanum ellipticum and Ixtolaena leptolepis, Nitre hush

(Nitraria schoberi) is common on the floodplains,

QUANTITATIVE EstimaATIONS AND Maprinc or Busn Density

The dominant shrub species, that is the bluebushes (Kochia sedifolia and

K, planifola) and saltbush (Atriplex vesicaria), are very important constituents

of arid pastures. Although sheep cannot exist for long periods on any of these

species, when they are partly defoliated under drought conditions and when no

herbage or grass is available, they are extremely valuable as a drought reserve

and play a very important role in minimising soil erosion. The presence of these

quite palatable and highly drought-resistant perennials means that fluctuations

in sheep numbers due to seasonal conditions are much smaller than in areas

Where shrubs are absent and grazing is dependent on herhage and grass.

When this survey was commenced it was recognised that some rapid method

of estimating the density of shrub dominants and of mapping pastoral areas on

this basis would have to be developed. The delineation of the boundaries of the

different vegetation associations alone does not give an adequate picture of the

grazing potential. It is also necessary to indicate the state of preservation of the

country, To enable the large areas involved to be traversed a method depending

upon visual estimations of density was used but at the same time the method

had to give a sufficiently detailed picture to enable station managers lo see what

bush losses had occurred through grazing on the properties under their control,

and to enable significant changes in bush density that might occur in the future

to be measured.

Certain fairly well-defined stages of degeneration of shrub dominant vegeta-

tion can be recognised and the following categories were adopted:

Stage 1 Unstocked country or country which has suffered only slight bush

thinning.

Stage 2 Noticeable bush thitining but the country still very well preserved.

Slight increase in the amount of Bessia spp.

Stage 3 Marked bush thinning. Pronounced growth of Bassia spp.

266

Stage 4 Little bush remaining through the Bassia spp.

Stage 5 Trace of bush remaining; mainly Bassia spp.

Stage 6 All bush gone. Ground layer dominated by Bassia spp.

The next step was to define these stages according to the number of bushes

per unit area that each represented. Counts were made of bush numbers in each

stage of degencration by running one-tenth mile traverses with a car. By mark-

ing the point of commencement, driving one-tenth mile by the speedometer and

walking back the plants are easily coutited because the tyre marks remain plainly

visible. This gives a strip five feet wide or a basal area 2/33 of an acre. All

subsequent figures refer to the number of bushes in this unit of area. All

bushes whose butts are on or within the wheelmarks are counted. When making

the counts it is mecessary to choose stands consisting of mature bushes, as seed-

lings often grow more densely than plants in a mature bush stand.

The following are the bush numbers on 2/33 acre areas for country In which

Kochia sedifolia is the dominant species:

Stage 1 more than 46 bushes (Plate XXIII, Figure 4),

Stage 2 35 -— 45 (Plate XXIV, Figure 1),

Stage 3 15 — 34 Plate XIX, Figure 3),

Stage + 5 — 14 (Plate XXIV, Figure 2),

Stage 5 1 - 4 (Plate XXIV, Figure 3},

Stage 6 0;

while for Alriplex vesicoria and K. planifolia dominant areas the figures are a5

follaws+

Stage 1 more than 160 bushes (Plate XXI1, Figure 4),

Stage 2 135 -—159 (Plate XXIV, Figure 4),

Stage 3 55 +134 (Plate XXV, Figure 1),

Stage 4 15 — 54 (Plate XXV, Figure 2),

Stage 5 1 — 14 (Plate XXV, Figure 3),

Stage 6 0.

However, bush density varies not only with the grazing treatment the country

receives but also with the type of soil. Thus the lower stages do not always

indicate degeneration from Stage 1 density. For example, when K. sedifolia

grows on Wilgena soil the density of the bluebush is never sufficient to give a

count of more than 29 bushes on 2/33 acre, so that even prior to stocking this

type of country is never better than Stage 3, Stage 1 country is therefore the

standard to which lower densities due to either grazing or soil type are referred.

To determine the amount of bush lost through grazing it is therefore neces-

sary ta record not otly the present bush density but also to estimate the probable

density of bush prior to grazing. A good correlation exists between the type of

soil and the density of the bush that it supports. Thus, as pointed out, Wilgena

soil supports Stage 3 K, sedifolig in unstocked and well-preserved areas through-

out the North-West, so that even when all the bush has been removed by grazing

it is reasonable to asstime that originally the areas of this soil had a bush density

equal to Stage 3, In addition to this correlation between soil and bush density,

ether evidence of the original density of the bush cover usually exists. It can

often be determined from observations of adjacent paddocks, remains of dead

bushes or portions of paddocks furthest away from stock watering points.

The maps showing bush density (fig. 12 and 13) are prepared from records

compiled by making car traverses across the country on as detailed a grid as can

be obtained. It is often possible to achieve sufficient coverage by driving the

station tracks which link up the watering points and thus traverse all the pad-

docks. Where sufficient coverage cannot be obtained in this way it is necessary

PLAN SHOWING ORIGINAL BUSH — DENSITY LEGEND

Number of bushes ng gcre for

woe —_ Kochia Blonitalio Kochia sedifolia

an .

a oy ee fee Atriplex _vesicaria

i More than KO More than 46 Stage |

135 — 159 SS—4S Stage 2

S5—IS4 5-34 Stage 3

IS—54 5/4 Stage 4

i—4 '-4 Stage S

=4 is) oO Stage 6

{ }

1 Kochig planifolig and Camplled dy

1 Atriplex vesicaria A.W Jessep, M. Se.

: So Conservation Branch ,

i Rochia secifolia Department af Agriculture.

— nN

Svotion Boundaries

° < a

fests Lee oiloe

{er the hie —$— =

The figures refer ta the overage number of bushes far each

i in & ,

grea in ee acre

== — — ~~ —

7 yg

; : : a a]

Enibare Ohne > tt ky BN zt miner — j

“By * f= BT |

$ TStSRtGF

% =f =

= in =}

1 rs) —|

; 7 Is 4

\ Lane Lapyriony

: ¢ —

\ Pest Sen Weeada Caw if ————

7 { La 35 —

| Re wat. thks \ facby Downe USSR Se

2 beams

\ . i) pe

, a

f !

i 2 eS By

t Bld. Comp Wi

~ °

Fig, 12

Lane

SRIRTIN GR

267

to make cross-country traverses on compass bearings. Not all station tracks

enable a correct impression to be formed of the general condition of the country

they pass through. Thus they may tend to follow watercourses which contain

only scattered K. sedifolia in the mulga and myall woodland country or sheep

may be travelled down them to the woolshed for shearing. In these cases road

traverses tniist be ignored in favour of cross-country observations,

The following is a typical record made in mulga-myall country (Acacia

aneura—A. brachystachya——A. sowdenii-K, sedifolia association complex):

Car speedometer reading when leaving Well No. 1, 65-2.

658 MyS 3-5 68-7 MyS 5

66-4 MyS 3-4 oo MS 3

66-7 M 6 69:2 MS 3-4

67-1 MyS 3 a4 M 6

674M 6

Speedometer reading at Well No. 2, 694,

. The speedometer readings refer to the points at which the different stages

of bush density end, for example MyS 3-5 occurs from Well No. 1 (652) to

65:8, that is for “6 mile. My is an abbreviation for myall, M for mulga and S for

Kochia sedifolia, The figures in the right-hand column arethe bush density

stages; where two figures are recorded the first is the estimated density stage

prior to stocking, while the second figure pives the present stage (thus 3-5

means originally Stage 3, now Stage 5). One figure in the right-hand column

indicates that degeneration has not been sufficient to result in the country being

placed in a lower density stage,

By multiplying the length of each stage over the total length of the transect

by the number of bushes in the midpoint of the range for that stage and adding

the results obtained for the different stages the average number of bushes in

2/33 acre for the area sampled by the transect, and hence its density stage, is

obtained. If calculations are made using figures of present bush density and

density prior to stocking the percentage of the original bush cover now remain-

ing can be determined. Approximately 6400 square miles of Kochia sedifolia

dominant country were mapped quantitatively, and it has been calculated that

this area retains 80% of its original bush cover, The Atriplex vesicaria and

Kochia planifolia dominant ateas (3,000 square miles) retain 65% of their original

bush cover.

Fifty-seven plants of Kochia sedifoka on 2/33 acre was the maximum den-

sity of bluebush recorded. Actually stands containing 50 or more bluebushes are

rarely encountered even where soil conditions are most favourable, so that for

the country to fall into Stage 1 the bush density must usually be increased by

the presence of bladder saltbush between the bluebushes, Most virgin stands of

bluebush alone have a density equal to Stage 2, The change from Stage 1 to

Stage Z, the first stage in the degeneration of bluebush country, is brought about

by destruction of the bladder saltbush through grazing. Stages 1 and 2 are

associated with Bon Bon and shallow Wirraminna soils, lower stages on these

soils usually being the result of overgrazing. On Wilgena soil the bluebush

count even under virgin conditions never exceeds 29 bluebushes on 2/33 acre,

A bluebush stand with a density equal to middle to higher Stage 3 appears

to make an ideally balanced pasture, as sufficient bush is present to. provide a

drought-reserve of feed and to maintain soil stability, but at the sarne time com-

petition is not so severe as to eliminate the growth of herbage and grass, Stages 4

and 5 occur naturally (that is wilhoyt any degeneration through grazing) on the

deeper sands and in watercourses.

268.

Stands of bladder saltbush and low blucbush in the North-West only have

a density equal to Stages 1 and 2 on the most favourable soil type, that is, Coon-

dambo soil, On Twins soil, even under virgin conditions, the density is never

greater than Stage 3 and the proportion of bluebush to saltbush itn well-preserved

country is about 7 to | on this soil, In Stage 1 stands of the two species on

Coondambo soil the proportion of saltbush to low bluebush is about five to four,

but in Stage 2 and 3 stands the proportion becomes about two to three, that ts,

grazing results in the destruction of a bigger proportion of salthush than blue-

bush, Both species are about equally palatable but the saltbush is not as resistant

to grazing, As with Kochia sedifolia an ideallly balanced pasture of low bluebush

and bladder saltbush is apparently one with a bush density equal to middle to

upper Stage 3.

DISCUSSION

The dominant trees and shrubs provide a drought reserve of feed and pro-

tection against soil erosion, but as the shrubs become defoltated under drought

conditions, trees are more valuable than shrubs during a prolonged drought. As

the trees are nor destroyed by stocking with sheep at any rate. correct grazing

management ig centred upon maintenance of the shrub cover.

At the same time the balance between herbage, grass and shrubs is important.

The carrying capacity of some bush stands has increased with stocking partly

as a result of the benefits derived from judicious pruning of the bush through

prazing but largely due to improvement in the shrub—herbage balance. Cotn-

petition for moisture is so seyere in dense bush stands that little herbage or grass

appears between the bushes even in good seasons, Actually a paddock growing

grass and bindyis (Bassia spp.) with little or no bush has a greater stock carrying

capacity in good years than a well-bushed paddock, but during drought times

stock losses occur earlier and they are heavier than in more densely bushed

paddocks. A profitable line of scientific investigation would be to evaluate the

merits of well-bushed, partly bushed and wholly denuded country in an endeavour

to arrive at the most favourable balance between bush and herbage and grass.

It would be possible perhaps to obtain an answer to the problem by carrying out

stiidies on the chemical composition (particularly protein) and digestibility of

the various species at different stages of growth, By relating these to the known

palatabilities and to forage production the value of different pastures could be

appfoximately determined,

The optimum density of bush stands is probably one equal to medium to

higher Stage 3 (see quantitative estimates). Degeneration of bush country pro-

ceeds through lower Stage 3 to Stages 4 and 5 and ultimately to Stage 6, when

no bush remains and the country carries a bindyi-dominant community. If graz-

ing is still excessive the palatable bindyis are destroyed, leaving a grass-dominant

stand whose protein supply is much lower than the bush-bindyi or bindyi stages.

Ultimately overgrazing results in destruction of the palatable perennial grasses,

leaving only ephemerals and unpalatable plants. Bladder salthush (Atriplex

vestcaria) is the most prolific seeder among the dominant shrubs. Blucbush

{Kechia sedtfolia) does not seed as heavily nor as frequently as saltbush but quite

seed crops are produced from time to time, whereas low bluebush

(K. plenifolia) produces little seed, Recolonization of a denuded paddock with

bush is an extremely slow process even where the surrounding paddocks contain

bush and hence a seed supply is available. Both saltbush and bluebush seed is

equipped for wind dispersal, saltbush seed being contained within a bladdery

fruit, while the bluebush fruit is winged. In spite of this, seed dispersal is poor

and this is the cause of the slow recolonization. While scattered bushes remain

through a paddock, however, regeneration can be quite rapid,

PLAN SHOWING PRESENT BUSH DENSITY

ee ee aie ea ae. Sc ome Ae

Ye ae hs hoe \ ie)

3 LEGEND Compiled by BW Jessep, M.Sc.

’ i. " ! 7 y So Gore a Agrhouture

a ¥ : Number of bushes inggacre for Pane. Vy!

! F | . :

if re ' | Kochia planifolia Kachio segifolia

end

iia. " += Atriplex vesicaria

7 hr eee? | More than #50 More than 46 Stage 7

4 (35—159 5-45 Stoge 2

5S—I3a IS—J4 Stage 3

oo (5—S4 s—/a Stage @

: .

(—/a I—4 Slage 5

Oo a Stoge 3

pe The figures refer to

the average number

bushes for each

area in a acre.

E> kechia plonitotio ong Atriplee vesicaria’

Kochio sedifatia

|--—~~Starjan» Boundaries

2 |

tar eH aL ey

D. Frame

Basra

OUT earn,

Adrien shee

f Ses

Fig. 13

289

It has already been pointed out that competition for moisture is an important

factor in the arid plant communities, and in this connection it is noteworthy that

most regeneration of bush commonly occurs where stocking has been heavy, for

example, around sheep yards and in corners of paddocks where sheep tend to

congregate. This increased regeneration is due to removal of grass and herbage

by the sheep, thereby allowing more moisture for bush seedling growth, If it is

necessary to thicken up a bush stand it follows that when the shrubs seed (and

this only happens during good years) the country should be grazed heavily to

reduce grass and herbage competition and then stocked lightly to allow seedling

establishment to take place.

Reseeding trials on denuded country carried ont at Bimbowrie station in the

north-east of South Australia have indicated that saltbush can be successfully

resown artificially, However, seasonal conditions must be favourable, and even

then costs of reseeding are out of proportion to the value of the land, In these

experiments the country was first furrowed, but the natural regeneration which

occurs in sparsely bushed paddocks indicates that ploughing should not be neces-

sary and that it should be possible to reseed denuded country by broadcasting seed,

Experimental research is necessary to determine the most economic paddock

size or the correct number of watering points fur a given area of country, It has

been pointed out that at present many of the paddocks are far too large, as sheep

only occasionally graze beyond a four-mile radius of the watering points under

normal rates of stocking. Even within this four-mile radius the grazing imtensity

vaties enormously, the area around the water being overgrazed, while the country

beyond about two and a half miles is undergrazed, Much of the damage around

the watering points results from the tramping of the sheep, and furthermore in

large paddocks energy and hence feed wastage must occur through the shecp

walking in to water and out again in search of feed. Smaller paddocks result

in more uniform grazing and more efficient utilization of the country. Smaller

tobs on each water reduce destruction of bttsh through tramping and also energy

wastage through walking. Increased efficiency of utilization means that more

sheep can be carried, but at the same time the costs of improvements and main-

tenance of improvements are increased. The problem is an economic one of

balancing increased sheep numbers and hence returns against increased capital

expenditure. With ihe very small paddocks used in the myall-bluebush country

at Yudnapinna Research Station (Woodroffe, 1941), it has been found possible to

graze at the rate of 75 sheep to the square mile without bush loss, It is not

stiggested that these quarter square mile paddocks are of practical size, but they

do indicate that small paddocks enable a gteater number of stock to be carried

per square mile,

The size of the paddocks will naturally vary according to the carrying

capacity of the country, and while pastoral areas have no fixed carrying capacity,

nevertheless, the relative carrying capacities of the different plant associations

are known for the North-West. The community with the greatest carrying

capacity is the Atriples vesicaria —- Kochia planifolia association, and if its carry-

ing capacity is 100 the other communities would be rated approximately as

follows: Acacia sowdenii — K. sedifolia association (myall country) 55, 4. aneura

— A, brachystachya association (mulga country) 45, 4. aneura— A. brachystachye -

A, tetragonophylla association 40, K. sedifolia association 35, Atriplex vesicaria—

ixiolaena leptolepis association 35, A, vesicaria—Bassia spp. association 35,

XK. plansfolia — Bossia spp. association 30, Acacia linophylla—A, ramulosa associa-

tion 25, Zygochloa paradoxa association 20, Kochia planifolia — Atriplex vesicaria —

K. sedifolia association 20, A, rhagodioides association 14, and K, planifolia asso

ciation 14,

270

These ratings refer to the above communities only where they occur in the

North-West, that is, on particular soils and in a particular climatic zone. Com-

munities dominated by the same species in other parts of the pastoral country

will not necessarily have the same relative carrying capacities.

As in all the pastoral country of South Australia, in the North-West there

is no significant regeneration of the dominant trees, in this case rhe mulgas and

myall. The factors responsible for this state of affairs are not fully known and

progress in this direction requires knowledge of the autecology of the species.

Possible contributing causes include seasonal conditions, absence of firing, lack of

seed, competition with parent trees and effects of rabbits and stock. While loss

of surface soil or deterioration in soi] structure may be of some importance else-

where, these factors can play no part in the sandy soil areas of the North-West.

Regeneration js equally poor in the unoccupied country west of the area discussed

4 this paper.

Practically the only areas where established seedlings are found are where

the country bas been burned and in some swamps and watercourses, The seeds

of these spectes haye hard eaats which are cracked by the fires and this may be

at least partly responsible for the increased germination following burning. There

is ample evidence throughout the mulga and myall woodlands that prior to white

settlement much of the country had been burned. Most of these fires were pro-

bably started by blacks as a means of securing game, Firing no longer takes

place to any extent.

The fact that other than in burned country regeneration is mostly restricted

to swamps and watercourses stggests that moisturé may be a limiting factor

preventing widespread regeneration. The writer has tead that regeneration of

mulga following rolling is a common occurrence in Queensland where the average

tainfall is between 11 and 13 inches. In South Australia, however, the mulge

country is more arid receiving between 5 and 8 inches average annual rainfall,

From the records available it appears that the little regeneration of mulga and

myall that has occurred in this State has followed yery heavy rains, Some inter-

esting information in this connection has been stipplied concerning a growth of

young mulgas around the Bulgunnia homestead. This is situated in a depression

and following 587 points of rain in 13 hours in February 1938 the homestead was

flooded. Seedling mulgas “were first noticed around the homestead between

January and June 1949". For the first six months of 1939 good rains were again

experienced and the mulgas became firmly established, By July of 1946 they had

reached a height of 2’6% to 3°. However, some of them had appeared in the

homestead garden where they were not dependent solely on natural rainfall but

received additional water and these had reached a height of 812’ by July 1946,

All the records indicate that the young mulgas depending on natural rainfall have

averaged an increased growth m height of 4”-6" each year, but this 1s of no value

a5 a measure of growth rate.

However, during the last five years there have been other rains similer to

those of 1938 and a run of very good seasons has been experienced and yet prac-

tically no regeneration or even germination has been observed. An interesting

point arises here. Mulgas (and myalls) must be very long-lived trees and yet

some of the recent rains have resulted in so much water collecting in the swamps

that many of the mature mulgas growing in them have been killed as a result of

being Hooded, that is, the swamps have recently contained water for a longer

period than at any previous time during the life of the trees.

Competition with patent trees may play some part in preventing regeneration

but this can no longer be considered a very important factor because, as pointed

ou! earlier, about one-third of the mature muylgas and one-fifth of the mature

27)

myalls have died. Tyree death seems to be equally severe in the unoccupied

country. It is interesting to note that competition among young myalls does not

result in reduction in the density of the stand until the trees are well established.

Thus in the country which was burned on Yudnapinna in 1922 there is now 2

very dense growth of “young” myalls, so much so that the trees are frequently

touching, and yet no deaths have occurred and, in fact, all the trees appear very

vigorous. In stands of mature myalls, on the other hand, the individual trees

are quite scattered.

Lack of seed may well be an important factor preventing widespread rey

generation. Although the mulgas in particular seed very abundantly during good

years, an examination of the pods while still on the trees shows that a large pro-

portion of the seeds are destroyed by insects, It is eyen more difficult to find

undamaged seeds on the ground. Stock graze young mulgas under certain con-

ditions but rarely to the extent of killing them, and furthermore regeneration is

no better in the unstocked country. Rabbits, too, ringbark many of the young

plants, but it is felt that neither stock nor rabbits are primarily résponsible for

the absence of widespread regeneration and that the fundamental fact 1s that there

is actually a lack of germination, A combination of severa) factors is likely to be

important, for example, seed supply and favourable seasonal conditions,

APPENDIX A

THe Ecoryres or Sattausn (ATRIPLEX VESICARIA)

Wood (1936) has described three ecotypes of 4. vesicaria from Koonamore

station in the north-east of South Australia, The ecotype associated with soils

containing heavy lime at shallow depth (Form A) is an erect woody bush. It

eecurs in the North-West on Wilgena and Bon Bon soils in association with

bluebush (Kochia sedtfolia), mulga and myall. SBladders are most commonly

absent from the fruiting calyx or small bladders less than half the size of the

bracts may be present. At Koonamore the average dimensions of this ecotype

are height 32 em and diameter’ 34 cm,, but in the North-West both average height

(37 em.) and diameter (42 cm.) are slightly greater,

The second ecotype (Form B) is found on silty and sandy soils at Koona-

more, but in the North-West is confined to Twins soil. As Wood (1936)

points out fruits are generally without bladders, although occasionally bladders

up to a third the size of the bracts are present, Form R is a very woody bush

with a more erect growth habit than Form C. The bushes are larger than those

of any other strain—at Koonamore they average 40 cm. high and have marrow

lanceolate leaves, while in the North-West the leaves are obovate and the average

height is 58 em. and the average diameter is 73 cm.

Form C is found on silty soils at Koonamore and is a robust, rounded bush

about 50 cm. high. Very large bladders are present on the calyx. In the North-

West the form has comparatively small leaves and is restricted to soils containing

clay within an inch or two of the surface (Mount Eba, Arcoona and Cocber Pedy

soils}, Bushes growing on Mount Eba soil have an average height of 45 cm.

and an average diameter of 52 cm. and larger bladders than those developed

when the ecotype is growing on the other soils. On Cooher Pedy and Arecoona

soils the bushes are somewhat stnaller (avetage height 35 cm. and average

cliameter 46 cm.},

A previously undescribed ecotype (Form D) is associated with deep sandy

soils (Wirraminna type) in the North-West, It is characterised by an erect

woody growth habit and by the presence of very large bladders on the fruiting

calyx. Form D is a Isrge ecotype having an average height of 55 om. and an

average diameter of 52 cm.

272

The natural soil preferences of the various ecotypes of saltbush should be

considered when reseeding areas of country to this species. Better results are

likely to be obtained by using Form A on calcareous soils, Form C on heavy-

textured soils containing little or to lime and Form D on sandy soils.

Form C is both vigorous and a very prolific seeder, while Form A is also

a prolific seeder and Form B is fairly prolific. Form D seeds less heavily than

the other ecotypes and is not resistant to grazing.

ACKNOWLEDGEMENTS

Numerous discussions with Dr, C. G, Stephens, Division of Soils, Com-

monwealth Scientific and Industrial Research Organisation, and Mr. K. Wood-

rofte, of the Department of Agronomy, Waite Institute, were very helpful.

Professor J. A. Prescott, Director of the Waite Institute, and Mr. J, A.

Beare, Soil Conservation Branch, Department of Agriculture, assisted by criti-

cally examining the manuscript. Throughout the course of the investigation

Mr. K. S. Rymill and Mr. J. Johnstone, Pastoral Inspectors, Lands Department,

readily made available plans and official records, Figures 6 and 7 were drawn

up by Mr. E. Leaney, Waite Institute.

The writer lived at the various station homesteads scattered throughout the

North-West while carrying out the field work, and without the co-operation and

hospitality of the pastoralists the work could not have been done. For 18 months

Mount Eba, formerly on the Adelaide to Darwin airline, was the centre from

which the field work was carried out, and it is to Mr. and Mrs. Crombie of

Mount Eba that the writer is most indebted. Mr. Crombie also provided facilities

which enabled the writer to carry out maintenance work on the vehicle used on

the survey, The writer is also extremely grateful to the following people for

their hospitality and assistance: Mr, and Mrs. K. Neill of Bulgunnia, Mr. and

Mrs. T. C. Young of Kingoonya, formerly of North Well, Mr. and Mrs. R.

Jenkins of Wirraminna, Mr. and Mrs. J. Pick of Coondambo, Mr. and Mrs,

C. Goode formerly of Malbooma, Mr. and Mrs. C. Greenfield of Billa Kalina,

and Mr. and Mrs. F. Stoddart of Mount Vivian.

REFERENCES

Bacnorp, R. A. 1941 The Physics of Blown Sand and Desert Dunes, London

Buacx, J. M. 1929 Flora of South Australia. Govt. Printer, Adelaide

Crocker, R. L. 1946 Post-Miocene Climatic and Geologic History and its

significasice in relation to the Genesis of the Major Soil Types of South

Australia. C’S.I.R, (Aust.), Bull. 193

Crocker, R. L. 1946 The Soils and Vegetation of the Simpson Desert and

its Borders. Trans. Roy. Soc. 5. Aust., 70, (2)

Crocker, R. L., and Sxewes, H. R. 1941 The Principal Soil and Vegetation

Relationships on Yudnapinna Station. Trans. Roy. Soc. S. Aust, 65,

(1)

Crocxer, R. L., and Woop, J. G. 1947 Some Historical Influences on the De-

velopment of the South Australian Vegetation Communities and their

bearing on Concepts and Classification in Ecology. Trans. Roy. Soc.

S. Aust,, 71, (1)

Davin, T. W. E. 1932 Explanatory Notes to accompany a New Geological Map

of the Commonwealth of Australia. Govt. Printer, Sydney

Davison, J, 1936 Climate in Relation to Insect Ecology in Australia, Bio-

climatic Zones in Australia, Trans, Roy, Soc, S. Aust., 60

74, Plate XII

Vol,

Aust., lol

Soc, S

us. Roy.

“Maa [aqeJY UO aj}PEI Jo qo V ‘oytuEpuooy ye daays notes pean’,

- Sig ge Sty

“YSHAaN[T By JO uONtiySap IYI

JAE BAIE ay pazuopor sel (MpNpIOL4s “IVA VAdpf{id) DUPON )

qnaysaapun agp, ‘SoyUeL Jaypews ayy JO YO Supyearq att

Yano uoywyOap ayeydwes wosry synsas wad ‘"pexesjsap

Ajajaydwwos ysngqanyq aif] pure parry taaq aary soos) [pes att [PV

‘UONTIS BUITUIRAAT AA “LULOYSpUIM PB Aq Ua yorq sesyny ‘LOLS OGIIEPUOOD UO TIO]S [TeIL QaAas BAG Pasnes see

: ' VY } : I It C

c 3t4 1 ‘Sty

Vol. 74, Plate XIV

Soc. S. Aust., 1951

aus. Roy

‘sosgjnu ayes UTM

payeisosse sARMye salads v ‘(sisuayma4np DIINIPT) aT NBM ayuiuss

ale sqniys ayy “WONRS Bluunepy WO aytuBss Jo doasjno wy

+ Bt

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Z Sty

‘PAAOWaT Haad SRY SqMIYys ay]. UaaM yay Sse puy

ASQ ML TY 'RF6L Bump uoyes sumacy Aqxeyp uo punoss

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¢ By

“YSHYTYLS OF FO Yap si]) pasavs aarti] PUR aonay WLWIAA ayy pur

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ALT “OYP] ey] JO aspa ay punosmw sumo Aq aangysiour ureygo

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au F A[WO st Joupamry oye] JO alOys usay ou ayy ‘aAaMoTT

“payooys tase AGuanbasuos pue paidnas0un st aduay UrULIdA ayy

ysnosyy Aajqunos apy “Sunpooys SAvay ayinb yo ayids tr paataaus

SEY UPTYM Ysnqiyes JO puvjs poos AqaA PB St punoisaroy oy}

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at ]

Plaie XV

7A,

. Soc S. Aust, 19

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Trans

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FMMOTOF UVEL AYUTT UL JayLM JO salaur saat) OL OW |, DUOTSAMUT STIOAIITIS TO FUrSsoo VONYIS Ys) 54a [YY VO TM y

p Std g AMY

‘ones SMuayye Sr siurds pundur aryl taaayadq putas arp

usury UMA ay) Wosy dae quoy anod yup sBurds Aq

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SSuInSIp P2dO ayy PUNose opEIs SNO@AV}ar) Palfeayq JO Spunoyy S]k SPUMAY Suppo, ‘vpTEpeUpod) Jo tos ssMEyP Wosielagy ILL

7 Sy 1 St

Vol. 74, Plate XVI

.S. Aust., 1951

ia)

. Roy. §

Tran:

4snp yrs

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SIf jnoqe saunp Woy WoO} OF ayey ay Yo UMO]q ATasiey, sem

WinsdAS at]} SUOTIPUOD ANBUIYO Jap Jopuy) ‘aaeyins sy uo

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al} pataaod ATpeursi1o yisodap tunsdAs ayy ‘uornE}s euloog ey

uO ayRyes B JO s[ppru ayy ur (toy) wnsdés jo punom yw

f Bt

‘909s ALI YIM patarod st aovyans ayy asayAr

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aM Suimoys ‘woes Yay SAIL UO syMp Tenpisar omy

‘

‘Jaay OM] ST 'paAltap aay Ady. GoM losT

UOZMOY SmoOadotts 9} AUal] PUL ‘stoppnoq ayy JO ssauyoiyy wn

“XE AY, “AaTsHeq JNO Jo Joy ay uo yuiod “Buy stofaaans

ev ulioy Oy dn paid waaq aaRy Yorpar Aqpq JO ssapynoq azieT

ety

“AUN PULTGEL ay] JO 9aVTans ayy St ozLIOL

PAI] OY, “wOsuUBET ay] JO IsMID YRS ay} St PimMOssyorq

AUYM BY], “MONEIS EUUTLUIEIIT AA WO STR [RNpisea paddoy-yp4

I te

ate X

1951

ust.,

Trans. Roy. Soc. S. A

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y Bly

‘ssuisour) dummas aay spied ayy “Ones elt y

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Vol. 74, Plate XIX

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Vol.

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Roy. Soc.

‘Trans.

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Trans. Roy Soe. S. Aust., 1951

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rama is 1 Fi

273

Dickinson, S. B. 1942 The Structural Control of Ore Deposition in some

South Australian Copper Fields. Geol. Survey 5, Aust., Bull. 20

Howcntn, W. 1929 The Geology of South Australia. Govt. Printer, Adelaide

Jack, R. L, 1921 The Salt and Gypsum Resources of South Australia. Geol.

Underground Water Supply in portions of South Australia. Geol. Surv.

S. Aust. Bull. 14

Jessup, R. W. 1946 The Ecology of the Area adjacent to Lakes Alexandrina

and Albert. Trans. Roy. Soc. S. Aust., 70, (1)

Jessup, R. W. 1948 A Vegetation and Pasture Survey of Counties Eyre,

Burra and Kimberley, South Australia. Trans. Roy. Soc. S. Aust.,

72, (1)

Mawson, D. 1947 The Adelaide Series as Developed along the Western Margin

of the Flinders Ranges. Trans. Roy. Soc. S. Aust., 71, (2)

Murray, B. J. 1931 A Study of the Vegetation of the Lake Torrens Plateau,

South Australia. Trans. Roy. Soc. S. Aust., 55

Prescort, J. A. 1931 The Soils of Australia in Relation to Vegetation and

Climate. C.S.LR, (Aust.), Bull. 52

Prescott, J. A. 1944 A Soil Map of Australia. C.S.LR. (Aust.), Bull. 177

Ratcuirre, F.N. 1936 Soil Drift in the Arid Pastoral Areas of South Aus-

tralia. C.S.I.R. (Aust.), Bull. 64

Secnit, R. W. 1939 The Precambrian—Cambrian Succession. Geol. Survey

S. Aust. Bull. 18

Specut, R. L., and Perry, R.A. 1948 Plant Ecology of Portion of the Mount

Lofty Ranges. Trans, Roy. Soc. S. Aust., 72, (1)

STEPHENS, C. G. and Crocker, R. L. 1946 The Composition and Structure

of Lunettes. Trans. Roy. Soc. S. Aust., 70, (2)

WuireHouse, F. W. 1940 Studies in the Late Geological History of Queens-

land, Univ. Queensland Papers, Dept. Geol., 2, (n.s.), No. 1

Woon, J. G. 1936 Regeneration of the Vegetation on the Koonamore Vegeta-

tion Reserve. Trans. Roy. Soc. S, Aust., 60

Woop, J. G. 1937 The Vegetation of South Australia, Govt. Printer, Adelaide

‘Wooprorre, K. 1941 Shrub Pastures under Low Rainfall. Jour. Aust. Inst.

Agr. Sci., 3

274

ROYAL SOCIETY OF SOUTH AUSTRALIA (INCORPORATED)

Receipts and Payments for the Year ended 30th September, 1950

RECEIPTS PAYMENTS

£sad4a £ s. da £s.d £58. 4.

To Balance, Ist October, By Transactions (Printing &

1949 vert sagsd, | cate 281 17 6 Publishing Vol. 72, Pt.

» Subscriptions — a 158 16 8 Z; Vol. 73, Pt. 1; ¥ol.

» Government Grant for 73, Pt. 2) fons 919 14 2

Printing, etc, .... 400 0 0) , Reprints heads 38 12 6

» Sale of Publications and » Librariam on. se 28 14 0

Reprints: » Printing, ete, 0 ae 21 0 4

» Highways and Local w Postage we ae nae 30 0 0

Government .... aise 4112 0 » ‘Sundries:

» Sundries .., .w. we 39 6 9 8018 9 Lighting ie elt 6 12 11

—— Insurance sok bese 614 0

» Hire of Rooms .., 11 10 Repairs... esi 710 6

» Interest ... 207 8 4 Hire Ppihaspope sats 22 0

Petties..., at 394 0

—-._ 39 8 5

» Balances—30th Septem-

ber, 1950—

» Savings Bank of S.A. .., 1113 0

» Bank of Australasia... 5610 7

Less Outstanding

Chequesi1 5 0

212 0317 0 53213 7 6 6 7

£1,141 16 0 £1,141 16 0

Endowment Fund as at 30th September, 1950.

£sd° £8 4, £osd. £ os. d.

1949—October 1— 1950—September 30—

To Balance: By Reventie Account:

Australian Inscribed Balance sca 207 8 4

Stock .. 6,010 0 0 Australian Inscribed

Savings Bank ‘of S.A, 6218 7 6,072 18 7 Stock on w. 6,010 0 0

Savings Bank of S.A. 62 18 7 6,072 18 7

1950—September 30— wo nd 2 AS

To Interest:

Inscribed Stock Siew 199 14 6

Savings Bank of S.A. 71310 207 8 4

£6,280 6 11 £6,280 6 11

Audited and found correct. The Stock and Bank Balances have been verified by certificates from

the respective institutions.

F, M. ANGEL

N.S. ANGEL, A.U.A. Comm. } Hon, Auditors.

Adelaide, October, 1950 HERBERT M. HALE, Hon. Treasurer

275

AWARDS OF THE SIR JOSEPH VERCO MEDAL

1929 Pror. Water Howcnrn, F.G.S.

1930 Joun McC, Brack, A.L.S.

1931 Pror, Six Daveras Mawson, O.B.E., D.Sc., B.E., F.R.S.

1933 Pror. J. Burrow Crezann, M.D,

1935 Peor, T, Harvey Joanston, M.A., D.Sc,

1938 Pror. J, A. Prescott, D.Sc., F.A,I.C.

1943 Herserr Womerstey, A.L.S., F.RES,

1944 Pror. J. G. Woon, D.Sc, Ph.D.

1945 Cec T. Manvican, M.A., B,E., D.Sc. F.G.S,

1946 Hersert M, HALE

LIST OF FELLOWS, MEMBERS, ETC.

AS AT 30 MARCH 1951

Those marked with an asterisk (*) have contributed papers published in the Society's

Transactions. Those marked with a dagger (ft) are Life Members.

Any change in address or any other changes should be notified to the Secretary.

Note—The publications of the Society are not sent to those members whose subscriptions

are in arrear.

Date ai Honorary Fetrows

1945. *Biacx, J. M., A.LS., (Hon. causa), 82 Brougham Place, North Adelaide—f’erco

Medal, 1930; Fellow, 1907-45; Cowncil, 1927-31; President, 1933-34; Vice-President,

1931-33.

1945. *Fenner, C. A, E.. D.Se., 42 Alexandra Avenue, Rose Park, Adelaide—Fellow, 1917-45;

Council, 1925-28; President, 1930-31; Vice-President, 1928-30; Secretary, 1924-25;

Treasurer, 1932-33; Edttor, 1934-37,

1949, *CurLanp, Pror. J. B, M.D., Dashwood Road, Beaumont, S,A—Fellow, 1895-1949 ;

Verco Medal, 1933; Council, 1921-26, 1932-37; President, 1927-28; 1940-41; Vtce-

President, 1926-27, 1941-42,

FELLows.

1946, Axpre, Pror. A. A.. M.D,, D.Sc, PhD., University of Adelaide.

1927. *Avnerman, A. R., Ph.D., D.Sc, F.G.5. , Div, Indus. Chemistry, C.S.1.R.0., Box 4331,

G.P.0., Melbourne, Victoria—Council, 1937-42.

1931. Aworew, Rey. J. R,, c/o Methodist- Manse, Maitland,

1935, *ANprewarTHA, H. G., M.Agr.Se. D.Sc Waite Institute (Private Mail Bag),

Adelaide—Council, 1950. ;

1935. *Anorewartaa, Mrs, H. V., B.Agr.Sc., M.S., (nee H. V. Steele), 29 Claremont

Aventie, Netherby, S.A.

19290. *Awncer, F. M., 34 Fullarton Road, Parkside, S.A.

1939, *Ancer, Miss L, M., M.Sc., c/o University of Adelaide.

1945. *Bartcert, H. K,, L:.Th., 15 Claremont Avenue, Netherby, S.A.

1950. Berastry, A, K,, Harris Street, Marden, S.A,

1950, Brcx, R. G, B.Ag.Sc, R,D,A,, Linewood Park, Mittel, S.A.

1932. Becc, P. R., D.D,Se., L.D.S.,, Shell House, 170 North Terrace, Adelaide.

1928. Best, R.J., D.Sc. F,A:C.I., Waite Institute (Private Mail Bag), Adelaide.

1934. Brack, E, C., M.B., B.S., Magill Road, Tranmere, Adelaide.

1950. Bows, oi MB, BS. FRCS. (Eng), FRACS., 144 Hill Street, North

elaide, S.A. .

1945. *Bonytuon, C, W,, B.Sc, A.A.C.I, Romalo House, Rormalo Avenue, Magill, S.A.

1940. Bonyraon, Six J. Lavineron, B.A. (Camb.), 263 East Terrace, Adelaide.

1945. *Boomsma, C. D., M.Sc., B.Sc.For., 2 Celtic Avenue, South Road Park, S.A.

1947, Bowes, D. R., Ph.D, B.Sc. 51 Eton Street, Malvern.

276

Date of

Election.

1939. Brooxman, Mrs. R, D, (mee A. Harvey}, B.A., Meadows, S.A.

1945, Broucuton, A. C, Farina, S.A. 4 , _

1948, Bxownrns, T, G., BSc. (Syd.), Waite Institute (Private Mail Bag), Adelaide.

1944. a Sorc neg Miss N, T., M.Sc., CS.LR.O.,, Div. Plant Industry, P.O. Bax IG), Can-

berra, A.C.T.

1923, Burnon, R.S., D.Se., University of Adelaide—Couneil, 1946, .

1922. *Campnecc, T. D, D.D,Sc,, D.Sc, Dentai Dept. Adelaide Hospital, Adelaide—

Cotincil, 1928-32, 1935, 1942-45; Vice-President, 1932-34; President, 1934-35,

1944. Casson, P. B,, B.Sc., For. (Adel.}, 8 Benjafield Terrace, New Town, Hobart.

1929. Cunrstie, W., M.B, B.S., Education Department, Social Services, 51 Pirie Street

Adelaide—Treasurer, 1933-38. ;

1950. Coarstan, S. E, B.Sc. 6 Hampton Street, Hawthorn, S.A.

i949. Cotzrver, F. S, Geology Department, University of Queensland,

1930, *Corgunoun, T. T., M.Sc¢,, 10 French Street, Netherby, S.AA—Secreiory, 1942-43.

1907. *Cooxe, W. T., D.Sc., A.A.C.L, 4 South Terrace, Kensington Gardens, 5.A—Connell,

1938-41; Vice-President, 1941-42, 1943-44; President, 1942-43.

1942. *Coorer, H. M., 51 Hastings Street, Glenelg, 5.A- i

1929. *Corron, B. C., S.A. Museum, Adelaide—Council, 1943-46, 1948-49; Vice-Presidenl,

1949-50; President, 1950-. s

1924. oe Crespieny, Sir C, T, C, DS.O,, M.D. F.R.GP., 219 North Terrace, Adelaide,

1950. Drtanp, C, M., M.B,, B.S, D.P.MM, D.J.M., 29 Gilbert Street, Goodwood, 5.A,

1941, Dicxinson, S. B., M.Sc., 52 Burnside Road, Kensington,

1930. Drx, E. V., Hospitals Department, Rundle Street, Adelaide, S.A.

1944, Dunstoxe, S. M. L., M.B,, B.S,, 124 Payneham Road, St. Peters, Adelaide.

1931, Dwyer, J. M., M.B,, B.S., 105 Port Road, Hindmarsh, S.A.

1933. *Earpiey, Miss C. M., M.Sc., University of Adelaide—Counctl, 1943-46.

1945. *Epsonns, S. J., B.A., M.Sc., 56 Fisher Terrace, Mile End, S.A.

1902. *Enouisr, A. G., 19 Farrell Street, Glenelg, S.A-—Conncil, 1949-.

1944, Fenres, Miss H. M,, MSc., 8 Taylor’s Road, Mitcham, 5.A. _

1927, *Fintayson, H. H., 305 Ward Street, North Adelaide—Counedl, 1937-40.

1923, *Fry, H. K, DSO, M.D, 6.S., B.Sc. F.R.A.C\P,, Town Hall, Adelaide—Comneil,

1933-37; Vice-President, 4937-38, 1939-40; Pressdent, 1938-39,

1932. *Gmson; E. S. H., M.Sc, 297 Cross Roads, Clarence Gardens, Adelaide

1927, Goorrey, F. K,, Box 951H, G.P.C., Adelaide,

1935. +GoLpsacx, H., Coromandel Val’ey. S,A,

1925, +Gosse, Sr Janes H,, Gilbert House, Gilbert Place, Adelaide

1910, *Grant, Prov, Sir Kerr, M.Se., W.LP., 56 Fourth Avetue, St. Peters, 5.A.

1930. Gray, J. T.. Orrorso, S.A.

1933, Greaves, H., 12 Edward Street, G'lynde, 5.4,

1904, Grierita, H. B.. Dunrobin Road, Brighton, S.A.

1948. Gross, G. F., B.Sc. South Australian Museum, Adelaide—Secretary, 1950-.

1944. Guppy. D. T., B.Sc. Mineral Resources Survey, Canberra, A.C,T,

1922, *Hace, H. M., Director S.A. Museum, Adelaide—Verco Medal, 1946; Councit, 1931-34,

1930-; Fice-President, 1934-36, 1937-38; President, 1936-37; Treasurer, 1938-1950.

149 Har, DR, Mem Merna, via Quorn, S.A.

1946. *Harpy, Mss. J. E. (nee A. C Beckwith), M-Sc., Box 62, Smithton, Tas.

1944. Harrs, J, R, BSe., $4 Archer Street, North Adelaide, S.A.

1447, Hexnerson, D. L. W., P.M.B., 20 Bourke, N.S.W,

1944. Herrror, R. 1, B.Agr.Sc,, Soi] Conservator, Dept. of Agriculture, S.A,

1049, Hortoway, B. W., BSc,, 33 Kyre Avenue, Kingswood, S.A.

1924, *Hossretp, P. S., M.Sc., 132 Fisher Street, Fullarton, S.A i

1950. Howaan, P. F. B.Sc, c/o Great Western Consolidated, Bullfinch, W-A.

144. Huwerz, D. 5. W., 238 Payneham Road, Payneham, S.A,

1947, Horton, J. T., B.Sc, 18 Emily Avenue, Clapham

1928, Jrovurn, P., Kurralta, Burnside, S.A.

1942, Jenxrns, C. F. H., Department of Agriculture, St, Gearwe’s Terrace, Perth, W.A.

101s. *Jennison, Rev, J. C.. 7 Frew Street, Fullarton, S.A-

1945, *Jzssue, R. W., M.Sc., 3 Alma Road, Fullarton, S.A.

1910. Roce FE. A. M.D., M.R.C.S,, 1 Baker Street, Glenele-

7950. Jouns, R. K., B.Sc, Department of Mines, Flinders Street, Adelaide, SA.

1921, *Jonnsron, Pror. T. H., M.A. D.Sc., University of Adelaide—Porco Medal, 1935;

Council, 1926-28, 3940-: Vice-President, 1928-31; President, 1931-32; Secretary,

1938-40; Rep. Powna and Flora Board, 1932-39; Editor, 5.

bbs toners H, M,, Ph.D., MB, F.RG.S., Khakhar Buildings, C.P. Tank Read, Bon

y, Indie.

Dateot

Election,

1449. *Kins, D., M.Sc, 44 Angwin Avenue, Blair Athol, S.A, ;

1633, *Kivemwan, A, W., M.Se., University of Adelaide—Seeretary, 1945-48; Wice-Presi-

dent, 1848-1949, 1950-; President, 1949.50,

1922, Lxwnen, G. A. M.D. B.S, F.R.C.P, A.M.P, Building, King William Street, Adelaide,

1948, Lorntan, T. R, N., N.ULH, (N.Z.), Director, Botanic Gardens, Adelaide.

1949, Lowex, H. F., 7 Averme Road, Highgate, S.A.

1931, *Lupyxook, Mrs. W. V. (nee N. H. Woods), M.A., Elimatta Street, Reid, A.C'T.

1948. MeCuicocr, R. N., M.B.E, B.Sc. (Oxon), BAgr Sei (Syd.), Roseworthy Agricul-

tural College, S.A,

1938. Mapvern, C. B., B,D.S., D.B.Se,, Shell House, North Terrace, Adelaide,

1932. Mawn, E. A., C/o Bank of Adelaide, Adelaide.

1939. Marsnatr, T. J.. M.Agr.Sc., PhD., Waite Institute (Private Mail Bag), Adelaide—

Council, 1948-

1905, *MAwson, Por. Six Dovoias, O,B.E., DSc, BE, F.RS., University of Adelzide—

Vorco Medal, 1931; President, 1Y2A-25, 1944-45; Vice-President, 1923-24, 1925-25;

Council, 1941-43,

1950. May, L. H., B.Sc., 691 Esplanade, Grange, S.A.

1920, Mayo, Tae How. Me. Jusirice, LL.B, K.C., Supreme Court, Adelaide.

1950, Mayo, G, M. E, BAgSc.. Waite Institute (Private Mail Rag}, Adelaide, S.A,

1943. McCartHy, Miss D. F., B.A., B.Se., 70 Halton Terrace, Kensington Park.

1945. 7*Mines, K. R., D.Se., F-G.S., Mines Department, Flinders Street, Adelaide.

1939, Mixncuam, V. H.. Hammond, S.A.

1925, +Mrrcwec., Pror. Sir W., K.CM.G., M.A, D.Se,, Fitzroy Ter,, Prospect, SA.

1933. Mrrcnecr, Pror. M. L, M.Sc., University, Adelaide,

1938. Moornouse, F, W,, M.Sc., Chief Inspector of Fisheries, Flinders Street, Adelaide.

1936, *Mounrroro, C, P., 25 First Avenue, St. Peters, Adelaide.

1944, Munrreu,, J. W,, Engineering and Water Supply Dept,, Port Road, Thebarton, S.A,

1944, Neat-Saira, C. A. B.Agr.Sci, 16 Gooreen Street, Reid, Canberra, A.C.T,

194. Nines, A. R, B.A., 62 Sheffield Street, Malvern, S.A,

1945. *Norruoore, K. H., B.Agr.Se., A.LA.S., Waite Institute (Private Mail Bag), Adelaide.

1930, Ocxenuen, G, T, B.A, c/o Flinders Street Practising School, Flinders St, Adelaide,

1947. *OrxEL, I, L,, 65 Fifth Avenue, St, Peters, S.A,

1913, *Osporn, Pror. 'T. G, B., D.Sc, Department of Botany, Oxford, England—Councii,

1915-20, 1922-24; President, 1925-26; Vice-President, 1924-25, 1926-27.

1937, *Pargin, L, W,, MSec., ¢/o North Broken Hill Mining Co,, Melhourtie, Victoria,

1949. Parxryson, K, J., B.Sc. 8 Mooreland Avenue, Beverley, 5.A

3945. Patrrson, G., 68 Partridge Street, Glenelg, S.A.

1929, Pavuit, A, G,, M,A., BSc, 10 Milton Avenue, Fullarton, SA.

1926,. *Pirer, C, S., D.Sc., Waite Institute (Private Mail Bag), Adelaide—vumed), 1941-43;

Fice-President, 1943-45, 1946-47; President, 1945-46.

1948. Poware, J. K,, B.Sc, C.S.LR.O., Division of Biochemistry, University, Adelaide,

1947, Poynton, J. O., M.D, M.A. ChB, MRICS. L.RC.P., Institute Medicine, Vet.

Science, Frome Road, Adelaide.

1949. Pratre, R| G, 81 Park Terrace, North Linley, S.A,

1925. *Prescorr, Puor. J. A. CBE, D.Se., ALC. Waite Institute (Private Mail Bag),

Adelaide—l’erco Medal, 1938; Council, 1927-30, 1935-39; Pice-President, 1930-32;

President, 1932-33,

1926. Price, A. G., C.M.G., M.A., Litt.D., FARG.S,, 46 Pennington ‘Terrace, North Adctaide,

1945, Prvon, L. D,, M.Sc., Dip.For., 32 La Perouse Street, Griffith, N.S.W.

1950, *Rawnany, J. H., B.Se., Bureau of Mineral Resources, Melbourne Building, Canberra,

1944. Riceman, D. S&S. M.Sc, BAegrSe, CSR.O., Division of Nutrition, Adelaide.

1947, Rrenet, W. R., B.Sc. Oceanographic Institute, Gottenburg, Sweden.

1948. *Rimes, G. D., B.Sc., 24 Winston Avenue, Clarence Gardens, S.A.

1947, Rix, C, E., 42 Waymouth Avenue, Glandore, S.A,

1944. *Roprnson, E. G., M.Sc, 42 Riverside Drive, Sudbury, Ontario, Canada.

1950. Ruop, Pror. E. A., B.Sc. A.M., University, Adelaide, S.A.

1945. Rymmm,, J. R., Old Penola Estate, Penola, S.A.

1944, *Sanvars, Miss D, F., M.Sc, University af Queensland, Bristane, Queensland.

1950, ‘Saunpers, F. L., 79 Winchester Street, Malvern, S.A.

1933, Scnwerver, M., M.B., B.S., 175 North Ter, Adelaide.

1946, *Seantr, E, R, MSc, C.5.1.R.0., Division of Tndustrial Chemistry, Box 4331, G.P.O,

Melbourne, Victoria.

278

Date of

Election. ,

1924. *Seonir, R, W., M.A., B.Sc. Engineering and Water Supply Department, Victoria

Square. Adelaide—Secretary, 1930-35; Council, (937-38; Mice-President, 1938-39,

1940-41; President, 193940.

1925, *Sxeaxo, H., Purt Ellot, S.A.

1936. *Sueaap, K., Fisheries Research Diy. C.S.LR.O., University of W.A., Nedlands, W.A,

1945. Swerueap, J. H., M.Sc, B.A. c/o Anglo-Westralian Mining Pty, Ltd,

1934, Sarnkrizio, R. C., Salisbury, S.A,

1924. Simeson, F. N., Pirie Street, Adelaide.

1949. Simpson, D. A. MB, B.S., 42 Lockwood Road, Burnside, S.A.

1941. “Syme Fs Lanerorp-, H.Sc., Department of Post-War Recofstruction, Canberra,

AGT.

1941. Sourncorr, R. V., M.B,, B.S., 12 Avenue Road, Unley Park, 5.A,

1936. Sovtawoon, A. B, M.D., M.S. (Adel.), M-R.C.P., Wootoona Ter, Glen Osmofid, §.A

1947. *Sprecut, R. L,, M.Sc, 15 Main Road, Richmond, S.A.

1936. *Srricc, R. C., M.Sc. Mines Department, Flinders Street, Adelaide,

1947, Spurcive, M. B., B.AgSc, Agricultural College, Roseworthy, S.A.

1940. *Seay, A. H,, B.Sc., 63 LeFevre Terrace, North Adelaide, 5,A. ;

193K *Srernens, C. G., D.Sc, Waite Institute (Private Mail Bag), Adelaide.

1935. Sa SPAy, A. G, MAgr.Se, 11 Wootoona Terrace, Glen Osmonil, 5.A—Council,

1947,

1932, Swan, D. C, M.Sc, Waite Institute (Private Mail Bag). Adelaide—Secretory,

194042; Fice-President, 1946-47, 1948-49; Prestdent, 1947-48.

1948 Swann, F. J. W,, 38 Angas Road, Lower Mitcham, 5.A.

1934, Symons, I. G. 35 Murray Street, Lower Mitcham, S.A,—Editor, 1947-,

1929, *Tavuor, J. K., B.A. M.Se., Waite Institute (Private Mail Bag), Adelaide—Cownctl,

1940-43, 1947.,

1950, Taytor, G. [1., B.Sc., Departnient of Mines, Old Legislative Council Building, North

; Terrace, Adelaide, S.A, .

1948. *TaOMAR, 1, M, M.Sc. (Wales), University, Adelaide—Secretury, 1948-50; Counerl,

1938. “Txomas, Mrs. I. M. (nee P. M. Mawson), M.Sc., 36 King Strect, Brighton.

1940, Tomson, Cart. J. M., 135 Mititary Road, Semaphore South, 3.A,

1923, *Tixparz, N. B., B.Sc. South Australian Museum, Adelaide—Seeretary, 1935-36;

Council, 1946-47; Vice-President, 1947-48, 1949-50; President, 1948-49,

1945. Tiver, N. S, M.Sc., B.Agr-Sc., Waite Institute (Private Mail Bag), Adelaide.

1937, *Trumate, Pror. H. C., DSc, M.Agr.Se., Woite Institute (Private Mail Bag),

Adelside—Council, 1942-1945; WicesPresident, 1945-46, 1947-48; President, 1946-47.

1925, Turner, D. C., Brookman Buildings, Grenfell Street, Adelaide.

1950. Wrercx, S. T., Port Lincoln, 5.A.

1912, *Waro, L. K., 1S.0., B.A, B.B., D.Se,, 22 Northumberland Avenue, ‘lusmore—Council,

1924-27, 1933-35; Wire-President, 1927-28; President, 1928-30.

1941. *Warr, D. C., M.Agr.Sc,, Div. Plant Industry, C.$.1.R.0., Canberra, A.CT,

1936. WarerHouss, Miss L, M., 35 King Street, Brighton, S.A.

3939. *Weenine, Rev, B. J.,.5 York Street, Henley Beach,

1949, *Wecener, C. F., B.Sc, Depattment Mines, Flinders Street, Adelanle, S.A.

IMS, Waitrte, A. W. G,, B.Sc., Mines Department, Flinders Street, Adelaide,

195, Wuirtams, L. D., “Dumosa,” Meningie, S.A. _

1946, *Witsow, A. F., M.Sc, Untversity of W-A., Nedlands, W.A.

1938 *Wirson, J. O., C.S,1.R.O., Division of Nutrition, Ade’aide.

1930, *Womersrey, H., F.R.E.S., ALS, (Hon, causa), S.A. Museum, Adelaide—l*erco

Medal, 1943; Secretary, 1936-37; Editor, 1937-43, 1945-47; President, 1943-44, Vice-

President, 1944-45; Rep. Faung and Flora Protection Committee, 1945.

1044, *Womersuey, H. B. S., M.Sc, University of Adelaide.

1944. Wowmersiey, J. S., B.Sc, Lae, New Guinea,

1923. *Woov, Pror. J. G, D.Sc. PhD., University of Adelaide—Vereo Medal, 1944,

Council, 1938-40; Vice-President, 1940-41, 1942-43: Rep. Fauna and Flora Board,

1M0-; President, 1941-42; Council, 1944-48,

41950. Woovarp, G. D., 20 Kensington Road, Leabrook, S.A.

143, Woonranns, Haroto, Box 989H, G,P,O., Adeiaide.

145, Worrmtey, B. W.. B.A. M.Sc. A. Inst. P,. University, Ade‘aide,

1948, *Wrywonp, A. P., B.Sc, 4 Woodley Road, Glen Osmond, 5.4.

1949, Yeates, J. N. LS, AM.LE, AMIME., Richards Buildings, 99 Currie Strees,

Adelaide, S.A.

1944. Zimmen, W. J, Dip.For., F.L,S. (Lon), 7 Rapert Street, Footscray West, WIZ, Vic.

AUTHOR AND SUBJECT INDEX

279

VOLUME 74

(Names int italics denote that the described forms are new to science.)

Acanthocephala, Adstralian, No. 8: T. H.

Johnston and S. J, Edmonds, 1

Angel, F. M.: Notes on Lepidoptera of

Norther Territory, 6

Angel, L. M.; T. H. Johnston and: Life his-

tory of Plagiorchis Jaenschi, 49

—— =+-: Morphology and life cycle of

Apatemon intermedius, 66

Apatemon intermeditis from the black swan:

T. H. Johnston and L. M, Angel, 66 _

Archaean complex at Houghton, The: A. H.

Spry, 115

Blinmat: dome, The basic igneous rocks of

the; P. F, Howard, 165

Calcareous tufa deposits in northern New

Guinea: P. S. Hossfeld, 108

Capillaria orectolaki, 24

Couchman, L. E.: Notes on a collection of

Hesperiidae, 15

Craspedacusta sowerbyi in South Australia:

I. M. Thomas, 59

Crocidolite, an occurrence of: A, P. Wy-

mond and R. B. Wilson, 44

Edmonds, §. J.; Johnston, T. H,, and: Aus-

tralian Acanthocephala, No. 8 1

Geology of the Pidinga area; D. King, 25

Granites of the Palmer area: J. H- Rattigan

and C. FL Wegener, 149

Hiscock, I. D,: Life history of Hyridella

australis Lam., 146

Hossfeld, P. S.; Calcareous tufa deposits in

northern New Guinea, 108

Houghton, The Archaean complex at: A. H.

Spry, 115

Howard, P. F.: The basic igneous rocks of

- the Blinman dome, 165

Hyridella australis, life history of:

Hiscock, 146

I. D.

Jessup, R, W.: The soils, geology and vege-

ae of north-western South Azistralia,

Johnston, T, H., and S. J. Edmonds: Aus-

tralian Acanthocephala, No. 8, 1

——, and P. M. Mawson: Additional Nema-

todes. from Atistralian fish, 18

——, and L. M, Angel: Life history of

Plagiorchis Jaenschi, 49

—— ~——; Morphology and life cycle of

Apatemon intermedius, 66

King, D.: Geology of the Pidinga area, 25

Lepidoptera of the Northern Territory:

M. Angel, 6

Mawson, P. M.; T, H. Johnston and: Addi-

tional Nematodes from Australian fish, 18

Mediorhynchus corcoracis, 1

Nematodes from Australian fish; T, H,

Johnston and P. M. Mawson, 18

New Guinea, Calcareous tufa deposits in

northern: P. S. Hossfeld, 108

Northern Territory; Notes on Lepidoptera

of: F. M. Angel, 6

Ogyris hewitsoni parsoni, 9

Fentocora leucographa, 136

Plagiorchis Jaenschi: T. H. Johriston and

L. M. Angel, 49

Pidinga area, Geology of the; D. King, 25

Proleptus urolaphi,, 23

Rattigan, J. H., and C. F. Wegener: Granites

of the Palmer area, 149

Rimes, G. D.: Some new and little known

shorebugs, 135

Saldula cooronyensis, 139; S. psammobia,

140; S. breyicornis, 141

Shore-bugs (Heteroptera-Saldidae): G. D,

Rimes, 135

Soils and vegetation of County Buckingharn:

R. L. Specht, 79

Soils, geology and vegetation of north-

western South Australia: R. W. Jessup,

189

Specht, R. L.; Soils and vegetation of

County Buckingham, 79

Spry, A. H.: The Archaean complex at

Houghton, 115

Suniana larrakia, 13

Synemon wulwiylam, 14

Thomas, I. M.: Craspedacusta sowerbyi in

South Australia, 59

Vegetation; soils and, of County Bucking-

ham: R. L. Specht, 79

Vegetation, soils, geology and, of norih-

western South Austraha: R. W. Jessup

Wegener, C. F.; J. H. Rattigan and: Granites

of the Palmer area, 149

Wilson, R. B.; A. P. Wymond and: An

occtitrence of crocidolite near Roberts-

town, 44

Wymond, A, P., and R. B. Wilson: An

occurrence of crocidolite near Roberts-

town, 44

CONTENTS

PART I

Jounston, T. H., and Enmonps, S, J.: Australian Acanthocephala, No. 8 .... lant Sie 1

Ancer, F. M.: Notes on the Lepidoptera of the Northern Territory of Australia, with

Wescriptian Of Wew Species Cape alee te las cain | aes as eee ae ig es a

CoucuMan, L. E.: Notes on a Collection of Hesperiidae made by F. M. Angel in the Ke,

Northern Territory Re er Ta EMR eee SR aE ra a apy Sy kot 2

Jounston, T. H., and Mawson, P. M.: Additional Nematodes from Australian Fish ne :

King, “Def -Geolney otathesbicings Area to aw uaM paki yt ae ae kaw eh eS ‘

Wrymonp, A. P., and Witson, R. B.:. An Occurrence of Crocidolite near Robertstown, . :

South Australia —.... a 35 a The ae Re Sr 224, ae wa 44

Jounsron, T. H., and Ancer, L, Maperine: The Life History of Plagiorchis Jaenschi, |

a New Trematode from the Australian Water Rat eas ant 1% a ae AF

Tuomas, I. M.: Craspedacusta Sowerbyi in South Australia, with some Notes on its

Habits A Ch ee a en igen Ay gu Lg een ier oe: ac ee aaa SL:

’

Jounston, T. H., and Ancer, L. Mapetine: The Morphology and Liie Cycle of the

Trematode, Apatemon intermedius, from the Black Swan er ae fe: ww. 66

Specut, R. L.: A Reconnaissance Survey of the Soils and Vegetation of the Hundreds

of Tatiara, Wirrega and Stirling of County Buckingham, South Australia... Eero

Hossretp, Paut §.: Calcareous Tufa Deposits in Northern New Guinea .... et ww 108

Spry, Atan H.: The Archean Complex at Houghton, South Australia... ee ean,

PART II

Rimes, G. D.: Some New and Little-known Shore-bugs (Heteroptera-Saldidae) from the

Australian Region ... 0... came ln eh eg Ln Ai ey pa gr ef pete alc)

Hiscock, I. D.: A Note on the Life History of the Australian Freshwater Mussel,

Hyridella australis Lam. .... nee tyes ee si atc si i soso ee ne RO

Rarrican, J. H., and Wecener, C. F.: Granites of the Palmer Area and Associated

Granitized Sediments oe eat SU Aber be ua tne i ae we 149

Howarp, P. F.: The Basic Igneous Rocks of the Blinman Dome .., 9 ssn ane 165

Jessup, R. W.: The Soils, Geology and Vegetation of North-western South Australia... 189