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ANNALS

OF THE

NEW YORK

ACADEMY OF SCIENCES

VOLUME XXxiiIl

1913

Editor

EDMUND OTIS HOVEY

New York ( . wiNdig

Published by the Academy 5 ge q $35

1913, 1914 Ete

THE NEW YORK ACADEMY OF SCIENCES

(Lyceum or Naturat History, 1817-1876)

OFFICERS, 1913

President—EMERSON McMILLIN

Vice-Presidents—J. E>MUND WoopMaAN, W. D. MarrHew,

CHARLES LANE Poor, WENDELL T. BusH

Corresponding Secretary—HeENry KE. Crampton, American Museum

Recording Secretary—Epmunp Otis Hovey, American Museum

Treasurer—Henry L. DoHErty, 60 Wall Street

Librarian—Raureu W. Towrr, American Museum

Hditor—EpmMuND OtIs Hovey, American Museum

SECTION OF GEOLOGY AND MINERALOGY

Chairman—J. HE. WoopMAn, N. Y. University

Secretary—CuHar es T. Kirx, Normal College (January—September)

A. B. Pacint, 147 Varick Street (October—December)

SECTION OF BIOLOGY

Chairman—W. D. MarrHew, American Museum

Secretary—Wi.L1i1AmM K. Grecory, American Museum

SECTION OF ASTRONOMY, PHYSICS AND CHEMISTRY

Chairman—CHarLEs LANE Poor, Columbia University

Secretary—F. M. Prepvrrsen, College of the City of New York

SECTION OF ANTHROPOLOGY AND PSYCHOLOGY

Chairman—WENDELL T. Busy, 1 West 64th Street

Secretary—Rosert H. Lowrie, American Museum

2 ed

CONTENTS OF VOLUME XXIII

Page

Soo. EE seas Gad) Sn ee i

a PE ray ccd ba cies, oie elets 6) sale cl wie i's. w sietpie slwiere Vil wees ave ii

TEER As eefSiice SG) Bs Sa iii

ates of Publication and Editions of Brochures: ............0.ccceeccece iii

BUEN EMR Ty PANTER Teo ci tris) 6 c/ei cls <6 Social Os, 6 idiwlard 6 ath Sod 6 Seiad owe wu hvisvloee iv

A Physiological Study of the Changes in Mustelus canis produced by Modi-

fications in the Molecular Concentration of the External Medium.

OE 2 CE IS a ag 1

Corrections and Additions to “List of Type Species of the Genera and Sub-

genera of Formicide.’”’ By WILLIAM MorToN WHEELER............ 77

A Contribution to the Geology of the Wasatch Mountains, Utah. By Ferr-

Meat Mtns inter ar (Plates T-V1). occ. ccc ae cede ec ewucwsce 85

Lockatong Formation of the Triassic of New Jersey and Pennsylvania.

Pee RUS Se CE late (VER). oc os.. occ tic ees et twamac gees eens 145

Revision of the Genus Zaphrentis. By MARJoRIE O’CONNELL...........-.- Nee

The Manhattan Schist of Southeastern New York State and its Associated

Igneous Rocks. By CHARLES REINHARD FETTKE. (Plates VIII-XV) 193

mecorus OF Meetings, 1913. By EpMUND OTIs HOVEY.........0.-ccceeess 261

Pee AMIZAiOnN OL ENE! AGCAGEMY .. 2 66 5 ccc ok ale ec clae ele ce dsles vee wes ese 317

ene ret R a CNPP ROT fos oso na. ca so a 0 asia o'ere sias'e sb cpisleie ed Wedewls eo cee 317

OLE PEE COURIERS OG 2 OS Sal oe re ge eee eee ee 319

= DSL DET) (OST eSie 8 32 or A eee eee ere 320

SUS SUD, es a5g So ede 8 oe ee 323

Fay -FWS) oo) se ee ws oc cs RE EE ARTO NR RAE TE 324

een PAS at ecemoer, 1915. «6. os) cc's ve cw dinl's sole secu educawecd's 331

LEE scot Ste SOU de Sie 36 Se Pt et A Pe eae 343

DATES OF PUBLICATIONS AND EDITIONS OF THE BROCHURES

Edition

Pp. 1-75, 15 May, 1913 1200 copies

Pp. 77-83, 29 May, 19138 1150 copies

Pp. 85-143, 12 December, 1913 1400 copies

Pp. 145-176, 27 January, 1914 1050 copies

Pp. 177-192, 25 February, 1914 1300 copies

Pp. 193-260, 30 April, 1914 1650 copies

Pp. 261-353, 30 April, 1914 1000 copies

iii

LIST OF ILLUSTRATIONS

Plates

I.—A. Lower Half of South Fork Opposite Mill D. Big Cottonwood Can-

yon, Looking North.

B. Conglomerate at the Base of the Cambrian Quartzite in Little Cot-

tonwood Canyon, Just Below Alta.

II.—A. Photomicrograph of ‘“‘Tillite’ from the Head of South Fork.

B. Photograph of Hand Specimen of “‘Tillite” from South Fork.

III.—A. The Divide at the Head of South Fork and the Geologic Exposures

of the South End of the Reade and Benson Ridge.

B. Near View of the Upper Central Part of Fig. A.

IV.—A. Alta Overthrust and Geologic Exposures on the North Slope of

Little Cottonwood Canyon.

B. Near View of the East-sloping Algonkian Quartzite shown on the

Ridge of Fig. A.

V.—Topographic Map of the Alta Region, Wasatch Mountains, Utah.

VI— Geologic Map of the Alta Region, Wasatch Mountains, Utah.

VII.—The Lockatong Formation [map].

VIlI.—Hornblende Schist and Epidosite.

IX.—Pegmatite Dikes.

X.—Manhattan Schist and Augen Gneiss.

XI.—Specimens of Augen Gneiss.

XII.—Photomicrographs of Gneiss, Schist and Granodiorite.

XIII.—Photomicrographs of Schist.

XIV.—Photomicrographs of Phyllite and Schist.

XV.—Outline Map of Southeastern New York.

Text Figures

Change in A of blood of Mustelus due to immersion in fresh water until ut

SRT OE sD ee Bee 6 8 wise asad ie my, u) w Siac a's 6 nd Hcl Be o\t biel’ w aja Sie v eweeeedees 15

Change in A of blood of Mustelus due to immersion of fish in a hypertonic

TS gS ao ec i URE 0: 18

Relations of the A of blood to A of different solutions of sea-water....... 20

Respiratory movements in Mustelus 24 hours after destruction of spinal

a tea al Ucn Ioics' 0) cee 2 eie'w 02d: d Glew Misia. se 4.e b's & eid +» ot eie.e luce 21

Changes in A of blood of Mustelus due to immersion in fresh water fol-

ene TO TET MO SEM -VAELOL «6 <0. o cie oc ed cate nes ucleeebeleeeecueeeeae 23

Changes in the A of blood of Squalus due to transference from harbor

STE ES UT ATICT 6 Se se US rcs eg 33

Diagram showing comparative A’s of blood of Mustelus in sea-water, N;

in fresh water, F; and of saline solution, S, in which blood is first

eS say SIEM 6 Ol te CI or 38

Showing the difference between the ratios of volume of corpuscles to

plasma in normal blood, N, as compared with blood taken from fishes

eet See hs OM ME ERESH WALOE, FRss sac wes eed vcdccclues ceancvcusess 38

Showing the hemolytic effect of different NaCl solutions on the erythro-

cytes of four species of elasmobranchs and six species of teleosts..... 42

Showing changes in blood pressure of Mustelus canis due to immersion in

een A The cere ete Sieroter gies! oer cto ectaiietle vy ois ciclelve. 6. sie ais o's dcalee's «sewn see 56

Showing the change in the character of the respirations during an hour

ater immersion Of Mustelius in fresh. Water . ........:06 2 <ccccceweevee ce 57

Showing changes in heart beat of Mustelus due to immersion of fish in

ER ESE ey eee ge emer te ei cient ciciByp gle’ 6a: oele ve 8 4 eas sce alaterey a bis es e'ws 58

Showing changes in blood pressure and heart beat of Squalus due to trans-

ference from harbor water to fresh water from 11.06 a. M.to3.56P.M.. 60

Comparative rate of respiration and heart beat in Mustelus in sea-water.. 62

Stereogram of a portion of the Central Wasatch Mountains, Utah........ 89

Section exposed between mouth of Big Cottonwood and the head of Mill

RE et oh carga ag <i ns ds, ol.cis wis teva € a:e/eles élaie’ sei eves oa'e s o'ais 93

Section from Big Cottonwood Canyon northward to Willard, Box Elder

Sen RO ED Vas calc c\ciw eine «4 aisjeieie' sc ce else snes eo Seceeciawioewe 98

Sections to show the great unconformity between the Mississippian and

Pennsylvanian in the Wasatch and Uinta Mountains, and its value in

MECC RIOQUNUAING. . cic cca ween acme ceesececccranescet aces ee 119

Section between Argenta, in Big Cottonwood Canyon, and Alta, in Little

Cottonwood U........... Bee BAG Val aa ete als cian ub Secure ee ae Ia 134

Geological sections across the Lockatong formation from northeast to

Nae TOSI 2,50 chs chat oo.d Relea © Bi myelace’s wie: aele Shiv b wae e O'heip oan Mole ee 149

4h eee

= c r wad cote “ : id ? nh ,o 7 vv)

Ce Oe eee Srey FB ary 5 ‘a? 4 oe ; , $ Let Ni AN a i

OM oh fd q Wile ye NALA

Vernal) ee SOA A Deel edo jh

i ho

Cte

7 ai

i a

Ai a iv

ANNALS OF THE NEW YORK ACADEMY OF SCIENCES

Vol. XXIII, pp. 1-75

Editor, EpmMunp Ot1s Hovey

~A PHYSIOLOGICAL STUDY OF THE

CHANGES IN MUSTELUS CANIS

PRODUCED BY MODIFICATIONS IN THE

MOLECULAR CONCENTRATION OF

THE EXTERNAL MEDIUM.

G. G. ScoTtT

NEW YORK

PUBLISHED BY THE ACADEMY

15 May, 1913

THE NEW YORK ACADEMY OF SCIENCES

(Lyceum or Natural History, 1817-1876)

OFFICERS, 1913

President—EMERSON McMiuuin, 40 Wall Street

Vice-Presidents—J. EpDMuUND WoopMAN, W. D. MarrHEew

CHARLES LANE Poor, WENDELL T. BusH ~

Corresponding Secretary—HeENnry KE. Crampton, American Museum

Recording Secretary—Epmunp Otr1s Hovey, American Museum

Treasurer—HENkRY L. DoHeErty, 60 Wall Street

Inbrarian—RauPH-W. Tower, American Museum

Editor—Epmunp Otis Hovey, American Museum

SECTION OF GEOLOGY AND MINERALOGY

Chairman—J. E. WoopMAn, N. Y. University

Secretary—Cuartes T. Kirx, Normal College

SECTION OF BIOLOGY

Chairman—W. D. MattHew, American Museum

Secretary—WiItLu1amM K. Grecory, American Museum

SECTION OF ASTRONOMY, PHYSICS AND CHEMISTRY

Chairman—CHArLES LANE Poor, Columbia University

Secretary—F. M. Prepersen, College of the City of New York

SHCTION OF ANTHROPOLOGY AND PSYCHOLOGY

Chairman—WENDELL T. Busu, 1 West 64th Street

Secretary—Ropert H. Lowiz, American Museum

The sessions of the Academy are held on Monday evenings at 8:15 ,

o’clock from October to May, inclusive, at the American Museum of

Natural History, 77th Street and Central Park, West.

[Annats N. Y. Acap. Sci., Vol. XXIII, pp. 1-75. 14 May, 1913]

A PHYSIOLOGICAL STUDY OF THE CHANGES IN MUSTELUS

CANIS PRODUCED BY MODIFICATIONS IN THE

MOLECULAR CONCENTRATION OF THE

EXTERNAL MEDIUM?

By G. G. Scorr

(Presented by title before the Academy, 10 March, 1913)

CONTENTS

Page

ae TT Fer og cele pve ccc ee wee wens eet cscceneseses 2

an) s so sls hele ccs eevee celeeccceecccunws 5

ermal Osmotic pressure Of the blood of Musteélus.......... 0c. cece cece 6

Changes in the osmotic pressure of the blood due to alterations in the

erent ett SEO RICTMA) MICGIUM. .. 2... tec ct te ete cece 8

a oo a 8

Changes from the normal condition until death in fresh water and

RE rt M ciel ifs, sic <io cic sein sieis ccs dsceiesicsds atve viv dweece 11

Reverse changes brought about by a return to sea-water after immer-

sion of the organism in fresh water and concentrated sea-water.... 22

ime of the gills in the osmotic changes of the blood..................... 25

Osmotic pressure of the blood of an elasmobranch taken from brackish

a 30

Effect of loss of blood on the osmotic pressure of the blood............... 34

Additional changes in the blood due to alterations in the concentration of

ORR sn se cc ec cnc ete teense ensesenses 36

NE EET EPIEDCVEOS. . 0 2. cc ccc cect e neces etceswaes 36

Changes im the specific gravity of the blood....................0000- 44

Changes in the percentage composition of the water and the solids of

a 44

vaneee i the nitrogen content of the blood.............02ccceecccee 46

TRIE MECT OL CHE DIOOM. ... 2... cc ence ce cece te cece cncane 47

uerner ee OF ENG DIOOG. . 2.6... ee csc ee eee ce wept cca a evens 48

Regulation of the osmotic pressure of the blood..................c eee eee 51

Presence of salts in the external medium after immersion of Mustelus in

ee ee tie ona da asec videle ane teenie dan ae ween 54

Effects of changes in the osmotic pressure of the blood on blood pressure,

respiration and Cardiac activity............... cee cece eee eee eenees 55

ee os caw eas ce eee eees eee aeae waa se 63

IE nr SN ed hs so PE ig ae wie oad hone lee Wad Sd Shield od 71

te oe cca aie 6 8d Sie ecb e dannwin’ Sudn em uarea ae ee 73

1 Submitted in partial fulfilment of the requirements for the Degree of Doctor of

Philosophy, in the faculty of Pure Science, Columbia University.

9 ANNALS NEW YORK ACADEMY OF SCIENCES

INTRODUCTION

Differences in osmotic pressure have been held to explain many physio-

logical processes. It is a great temptation, for example, to ascribe the

passage of materials into and out of the cell to differences in molecular

concentration between the cell contents and the circulating medium; and

yet, such a process as the secretion of urine is not satisfactorily explained

by the physical theories of osmosis and diffusion. It does not necessarily

follow, however, that, because these theories in our present state of knowl-

edge fall short of a complete explanation of physiological processes, they

should on that account be altogether discarded, nor should this be taken

as an argument for vitalism. The full understanding of both the physi-

cal process and the associated chemical process would make clear the

physiological process. So that everything that can be ascertained with

regard to the passage of materials through membranes is of value to the

science of physiology.

A common method of determining the osmotic pressure of a solution

is by means of a determination of its freezing point. The degree of de-

pression of the freezing point of the solution below that of pure water is

proportional to the osmotic pressure of the solution. The amount of the

depression of the freezing point, or A, is usually obtained by the use of

the Beckmann apparatus. The form of apparatus that was used in the

determinations described in this paper was made by Goetz of Leipzig.

When in constant use at low temperature, there is a tendency toward a

slight re-arrangement of the molecules of the glass tube, and this results

in a contraction that is sufficient to introduce a slight error in the read-

ings. It is therefore advisable for any one working with this instrument

to make frequent determinations of the freezing point of pure water. In

the experiments here described, this procedure was followed and the

proper correction was always made in the calculations.

Various aspects of the osmotic relations of the body fluids of aquatic

animals to the surrounding medium have been fruitfully investigated.

The waters of the earth differ in their molecular concentration. Fresh

water contains but a very small amount of salts in solution. The water of

the ocean, with a specific gravity of 1.025, contains about 3.0 per cent of

salts in solution. The water of the Black Sea and the Baltic Sea contain

less salts than the water of the ocean because of the great influx into

them of river water. The Mediterranean and Red Seas on the other hand

contain more salts in solution than ocean water because of the excess of

evaporation over the inflow of fresh water. There is considerable varia-

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 3

tion in the osmotic pressure of the body fluids of animals that inhabit

these various waters. For example, the blood of fresh water invertebrates

and fishes is much more concentrated than the water in which they live.

While the body fluids of these forms is maintained at a constant osmotic

pressure, the surrounding water is by no means isotonic with the blood

serum. The A of fresh water is 0.025°, while that of the blood of fresh

water fishes is about 0.60°. ‘The blood of marine invertebrates and elas-

mobranch fishes has about the same molecular concentration as that of

the sea. The mean A of the waters of the Mediterranean Sea and the

mean A of the body fluids of the invertebrates and elasmobranch fishes

which inhabit it is 2.29°. The A of the water of the ocean is about 2.00°

and invertebrates inhabiting such waters have a similar A. In the case

of the elasmobranchs, it has been claimed that the surrounding medium

is isotonic with the blood. On the other hand, the A of the blood of ma-

rine teleosts is less than one-half that of the external medium. For

example, although the A of sea-water from the Baltic is 1.80°, according

to Dekhuysen (’04) the A of the blood of marine teleosts from these

waters is only 0.724°. The A of the blood of fresh water fishes is nearly

the same as that of the marine teleosts. The blood of other marine verte-

brates, such as chelonia and cetacea, and of the other fresh water and

land vertebrates is similar in its osmotic pressure to that of the marine

teleosts.

In view of the fact that the elasmobranchs constitute the highest group

to possess blood and other body fluids with an osmotic pressure near to

that of sea-water, it appeared to the present writer that an extensive in-

vestigation should be made of the effects of changes in the molecular con-

centration of sea-water upon the blood and other tissues of the elasmo-

branchs. Since a dilution, rather than a concentration, of the sea-water

would be the modification of the external medium to which these fishes

might be subjected in a state of nature, more attention was given to the

effect of dilutions of the external medium.

In physical experiments of an osmotic nature, two solutions are sepa-

rated by a membrane and the qualitative relations of the process by which

the fluids pass through the membrane is studied. In the present investi-

gation, the membrane with which we have to do is possibly one or any

combination of three living structures which separate the living substance

of the body from the sea-water. These three structures are: a, the skin

of the body; 6, the mucous membrane of the enteric canal; c, the mem-

brane of the gills. In the following pages, these will be termed the limit-

ing membranes of the body. Outside of these membranes is the sea-

4 ANNALS NEW YORK ACADEMY OF SCIENCES

water. Within the body, the rapidly circulating blood comes into such

relation with sea-water as to insure the exchange of gases. It is a com-

mon belief that, by virtue of these structures alone, the organism is main-

tained in osmotic equilibrium with the surrounding medium. How far is

this position tenable?

The relation of each of these structures to the solution within and

without the organism may be that of a freely permeable membrane, a

semi-permeable membrane or an impermeable membrane. The limiting

membranes of the marine invertebrate body have been shown to be quite

freely permeable. Sea-water is isotonic with its blood; but if the sea-

water is diluted, salts leave the body by way of these structures, and

water from without enters into the body with the result that the blood

soon attains the same molecular concentration as the outside medium.

Similar adjustments are said to take place in the case of the elasmo-

branchs. In this case, however, it is claimed that the resulting equality

is attained not by the loss of salts from the body but by changes in the

relative amount of water in the blood. Further investigation of this

matter seems necessary. In addition the following questions call for in-

vestigation. What are the lethal limits of departure from the normal

osmotic pressure of the blood of elasmobranchs? Is the modification in

the osmotic pressure of this blood dependent upon the time of immersion

in the changed external medium? Is the change dependent upon the de-

gree of change in the osmotic pressure of the external medium? Does a

lethal change in the osmotic pressure of the blood affect the corpuscles?

If so, in what manner and to what degree? What is the effect of the

modified blood upon blood pressure, heart beat and respiration? Is there

any evidence of a mechanism for the maintenance of the normal osmotic

pressure of the blood? Is there any evidence that a new and permanent

normal osmotic pressure of the blood is established under conditions in

which the concentration of the external medium is permanently modi-

fied? Does the blood of the elasmobranch under such conditions remain

of the same molecular concentration as that of the modified external

medium? Evidence on these and related problems is offered in the pres-

ent paper.

The experiments described below were carried on at the Biological

Laboratory of the United States Bureau of Fisheries at Woods Hole,

Massachusetts, and at the New York Aquarium. I wish to thank the

Commissioner of Fisheries, the Hon. George M. Bowers, Dr. Francis B.

Sumner and Mr. T. E. B. Pope for the many facilities extended at Woods

Hole, and to extend thanks likewise to Dr. Charles H. Townsend, the

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 5

Director of the New York Aquarium. I must also express my indebted-

ness to Professors Frederic S. Lee and F. H. Pike of the Department of

Physiology of Columbia University for many helpful suggestions.

HISTORICAL

Sumner (706) published a brief summary of investigations of the os-

motic relations of the body fluids of aquatic animals to their surrounding

medium. Bottazzi (’07) has given an extensive review of the literature

bearing on this subject. I will limit this synopsis, therefore, to a brief

statement of investigations on the osmotic relations of the elasmobranchs

to the surrounding medium. Constant reference will be made to investi-

gations on other forms in the pages that follow.

Mosso (790) observed that elasmobranchs died very soon after being

placed in fresh water. He explained the death as being due to the fact

that the erythrocytes were laked by the influx of fresh water into the

capillaries of the gill membranes, that the capillaries were clogged up

with these broken down corpuscles, that circulation was thus stopped and

that death ensued from asphyxiation. Von Schroeder (’90) found a large

amount of urea, 2.6 per cent, in the blood and other tissues of the normal

dog-fish. Quinton (790) confirmed this statement of von Schroeder’s.

Rodier (700) found at Arcachon on the southwest coast of France that

the A’s of the blood serum of different species of elasmobranchs were

similar, although slightly lower than that of the sea-water in which they

lived. The pericardial, peritoneal and uterine liquids had the same A as

the blood serum. He also corroborated the discovery of von Schroeder as

to the presence of urea in the blood of elasmobranchs and called atten-

tion to its role in determining the osmotic pressure of the blood. He

found that the bile and urine contained less chlorine than the blood.

Fredericq (’04) confirmed Rodier’s statement with regard to the réle of

urea in maintaining the osmotic pressure of the blood. He found that if

one puts a dog-fish, Scylliwm, into concentrated or diluted sea-water,

equilibrium between the osmotic pressure of the internal medium and the

external medium takes place in a short time, due to the withdrawal or

addition of water from the blood without involving the dissolved sub-

stances of the blood. Garrey (’05) found that the blood of the elasmo-

branchs from Woods Hole is isotonic with the sea-water and that dilution

or concentration of sea-water. causes a similar change in the blood of

selachians immersed in such modified media, but that death ensues before

an equilibrium is established. He concluded that the limiting mem-

branes of the selachian body are semi-permeable. Bottazzi (’06) showed

that not only the blood but also the urine, uterine fluid and the bile of

6 ANNALS NEW YORK ACADEMY OF SCIENCES

the cartilaginous fishes are isotonic with the sea-water. It should be

noted here that the A of the sea-water at Naples, where Bottazzi worked,

is much greater than that at Arcachon and Woods Hole, where Rodier

and Garrey respectively worked, and yet the blood of the elasmobranchs

from all three regions is approximately isotonic with the surrounding

medium. Bottazzi (708) came to the conclusion that the urea, found in

such large quantity in the blood, is formed by the muscles. Baglioni

(705) corroborated von Schroeder’s 790 statement with regard to the urea

in selachian blood. He also found that the elasmobranch heart would

continue to beat if filled with a solution of equal parts of urea and

sodium chloride, to which a trace of calcium salt was added. Dakin (708)

found marked changes in the osmotic pressure and chlorine content of

the blood of the dog-fish when the animal was immersed in fresh water.

One of his general conclusions is that the limiting membranes of the body

are impermeable to salts and that the changes observed in the blood are

due to variations in the relative amount of water. The limiting mem-

branes of the body are semi-permeable. Hyde (’08) found that injection

of solutions of sodium, calcium, potassium and magnesium salts in differ-

ent degrees of dilution produced changes in the blood pressure and the

respiratory and cardiac activity.

OsMOTIC PRESSURE OF THE BLoop oF Mustelus canis UNDER NORMAL

CONDITIONS

Emphasis is often placed upon the constant value of the osmotic pres-

sure of mammalian blood. Yet Findlay (705) calls attention to the fact

that there are diurnal variations in the osmotic pressure of human blood?

Thus he gives the A of human blood at 9 a. M. as 0.535°; at 12 M. as

0.558° ; at 1.30 P. M., after dinner, as 0.585°, and at 5.45 p. M. as 0.528°.

Bottazzi (706) found that the A of the blood and body fluids of marine

invertebrates in the neighborhood of Naples fluctuated between 2.195°

and 2.36°. He also found a similar range in the depression of the freez-

ing point of the sea-water. Rodier (00) working at Arcachon on the

southwest coast of France found that the A of the waters from the labo-

ratory basin varied between 1.87° and 1.95°, while the water from the

ocean itself was more constant, having A’s ranging from 2.05° to 2.09°.

Rodier in describing the Bay of Arcachon said: “Its waters have a den-

sity, salinity and osmotic pressure always less than sea-water, and vary-

ing with the season, height of tide, place from which the water was taken,

depth of water and time of day.” Rodier found that the freezing point

of the blood serum of different species of selachians was near to that of

their sea-water medium, although in many cases it was 0.04° to 0.05°

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 4

lower. He concluded that they had not become acclimated to the more

dilute bay water. Bottazzi (06) found that the A of the blood of Scy/-

lium stellare varied from 2.31° to 2.42°. He recorded the A of the blood

of Trygon as 2.378°, while Mosso recorded it as 2.44°. Bottazzi (06)

found the mean A of the blood of elasmobranchs at Naples to be 2.356°,

although the mean A of the sea-water was 2.29°. Yet Bottazzi concluded

that the osmotic pressure of the blood of cartilaginous fishes is similar to

that of the marine invertebrates in being identical with that of the sea-

water. Garrey (705) noted variations in the A of the sea-water at Woods

Hole and variations also in the A of the blood of elasmobranchs. ‘The

mean A of sea-water was 1.82°, while that of the elasmobranchs he studied

was 1.88°.

I have noted at different times the following A’s of the sea-water in the

laboratory of the Fisheries station at Woods Hole, namely: 1.76° ; 1.78° ;

mre = 1.80"; 1/83°; 1.855°>; 1.87°:.. The average of these is 1.81°-+.

The A’s of eighty specimens of Mustelus taken from the sea-water of the

laboratory basin at various times proved to be as follows:

TABLE I[.—Distribution of the freezing point of the blood of eighty specimens:

of Mustelus canis

mber Number

of aia A of cui eis A of specimens 4

n Peel? 7 | re a 6 1.90 °

i ae Cee 7 1.84 4) 1-91

1 1.76 5 1.85 9 1.92

1 1.78 4 1.86 6 1.93

1 1:79 4 1.87 2 1.95

5 1.80 6 1.88 1 1.98

3 Sil 2 1.89 1 2.03

2 dn

The mean depression of freezing point of the blood of the eighty speci-

mens is 1.869°. Garrey recorded a mean value of 1.88°. But the mean

A does not give a proper conception of the fluctuation in the osmotic

pressure of the blood. It is possible that the extremes of this series repre-

sent abnormal fishes. Greene (705) found a decrease of 32 per cent from

the normal A of the blood of the Chinook salmon in the case of an old

weak male and attributed this extreme variation to the pathological con-

dition of the specimen. On referring to the above table, it will be seen

that the greater number of A’s range between 1.80° and 1.93°. The dis-

tribution of A’s between these points is, with the exception of those at

1.92°, quite uniform. The average A is just about midway between these

two points. There are about as many A’s one side of the mean point

as on the other side. The mean A of Mustelus blood is .05° lower than

8 ANNALS NEW YORK ACADEMY OF SCIENCES

the sea-water in which it lives. It has already been noted that Rodier

(700) observed the same fact in connection with the elasmobranchs at

Arcachon. The observations of Bottazzi (706) reveal the same relation-

ship. Finally, Garrey’s 705 data agree nearly with mine.

The small difference between the A of the blood and that of sea-water

is important in that the molecular concentration of the blood of elasmo-

branchs is only approximately equal to that of the sea-water. According

to the above table, the blood of Mustelus can pass with entire safety

through a range of at least 0.15° in its osmotic pressure.

CHANGES IN THE OSMOTIC PRESSURE OF THE BLOOD DUE TO ALTERATIONS

IN THE DENSITY OF THE EXTERNAL MEDIUM

PRELIMINARY STUDY

It has been shown by a number of investigators that the osmotic pres-

sure of the internal body fluids of the marine invertebrates depends upon

the molecular concentration of the surrounding medium. Fredericq

(704), Garrey (705) and Dakin (708) have shown that this is true to a

certain degree of the elasmobranchs. Fredericq concluded that a new

equilibrium was established when he put Scylliwm into diluted or con-

centrated sea-water. For example, he put Scylliwm into diluted sea-water

having a A of 1.67° for twenty-seven hours, at the end of which time the

A of its blood serum was 1.70°. Another specimen was put into concen-

trated water having a A of 2.%2° for twenty-four hours, when the A of

the blood was 2.70°. Garrey (’95) found that the blood of Mustelus

canis, though normally having a mean A of 1.88°, changed to 1.45° after

an hour’s immersion in fresh water. Dakin (’08) found that when the

spiked dog-fish, Acanthias vulgaris, and the skate, Raia clavata, were put

into fresh water, there was a considerable fall in the osmotic pressure of

the blood. The mean A of these forms was 1.90°. In the four hours dur-

ing which the dog-fishes were in fresh water, the A of the blood changed

to 1.435°, showing a rise in the freezing point of 0.465° from the normal-

condition. The three specimens from which the above results were ob-

tained were nearly dead at the end of the experiment. The change in the

blood of the skate was not as great. This form was nearly dead at the

end of two hours’ immersion in fresh water, at which time the A of the

blood was 1.645°, showing a rise in the freezing point of .255°. In these

experiments of Garrey and Dakin, death took place before a new osmotic

equilibrium was established. I determined to ascertain whether there

was any relation between the duration of immersion in modified solutions

of sea-water and the change in the osmotic pressure of the blood. The

form used was Mustelus canis. As brought into the laboratory, the fish

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS - 9

were placed in a large tank of sea-water. The salt water supply was then

shut off and a stream of fresh water was turned into the tank. In a few

minutes the water in the tank was fresh. After certain periods of im-

mersion, the specimens were removed and a small quantity of blood was

drawn from the caudal artery of each for a freezing point determination.

It will be noted in the experiments that follow that the normal A of the

blood of each animal is not given. But one freezing point determination

was made in each case and that at the end of the time of immersion in

the experimental medium. It should be borne in mind, however, that the

mean A of the normal blood of Mustelus is about 1.87°. The results of

the first experiment are as follows: |

TaBLE II.—Change in the freezing point of the blood after various periods of

immersion in fresh water

(A of fresh water = 0.025 °)

Immersion time in

Specimen Fae i A of blood

1 35 162°

2 40 1.565

3 60 1.585

4 60 1.610

5 75 1.495

6 90 1.54

Individual changes in the freezing point of the blood are not the same

for the same time of immersion. In a general way, however, the osmotic

pressure becomes progressively less as the time of immersion increases.

I next concluded to ascertain the relation of change in the freezing

point of the blood to solutions less dilute than fresh water. In the second

experiment a solution of one-half sea-water and one-half fresh water was

employed. The A of this solution is about 0.90°. The results are as fol-

lows:

TABLE III.—Showing the change in the freezing point of the blood after various

periods of immersion in one-half sea-water and one-half fresh water

Immersion time in

minutes

Specimen A of blood

t 50 Py a

2 75 1.705

3 100 1.685

4 200 1.595

9) 245 1.555

10 ANNALS NEW YORK ACADEMY OF SCIENCES

In the third experiment a solution of three-fourths sea-water and one-

fourth fresh water was used. ‘The following results were obtained. The

A of this solution is about 1.35°.

TABLE 1V.—Showing the change in the freezing point of the blood after various

periods of immersion in three-fourths sea-water and one-fourth fresh water

Immersion time in

Specimen BREE Es 3 A of blood

il 30 Waa ge

2 60 1.74

3 100 1.73

4 230 1.64

Both solutions cause a rise in the freezing point of the blood. Yet the

rise is greater in the more dilute solution. On comparing the effects of

the two solutions, it is seen that the same changes in the freezing point

are produced in a shorter time in the second solution than in the third

solution. A similar effect is produced in still less time in the first solu-

tion, fresh water, than in the second one, which is one-half fresh water

and one-half sea-water.

The effect of concentrated solutions of sea-water was next measured.

Two such solutions were employed: one with a specific gravity of 1.035

and a A of 2.60°; the other with a specific gravity of 1.040 and a A of

3.15°. The results were as follows:

TABLE V.—Showing the change in the freezing point of the blood after various

periods of immersion in concentrated solutions of sea-water

Solution A—Sp. Gr. = 1.0385 A = 2.60°

Immersion time in

Specimen wiinnées A of blood

1 30 2.075°

2 50 2.115

3 7d 2.185

Solution B—Sp. Gr. = 1.040 A =3.15°

Immersion time in

minutes A, of blood

Specimen

1 35 "2.10 °

2 45 2.16

3 85 2.175

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 11

In both of the solutions more concentrated than sea-water there is a

lowering of the freezing point of the blood, an effect which is just the

opposite of that produced by fresh and dilute solutions. The initial effect

is greater in the more concentrated solution, although the final effect is

about the same.

Although in each of the five experiments the normal A of each speci-

men as taken from sea-water is not known, the results indicate that the

degree of change in the osmotic pressure of the blood depends upon the

molecular concentration of the external medium. The results differ from

those of Fredericq, in that they show that the osmotic pressure of the

blood does not become equal to that of experimental media that differ

markedly from the medium to which the animals are normally adapted.

Attention is again called to the different degree to which the individual

animals respond to modifications in the concentration of the external

medium. Some die sooner than others in these abnormal media. Hyde

(708) observed that the effects of operation varied in different skates.

For example, Hyde noted that when the same operation was performed

upon two animals apparently in every respect alike, in the one case the

effects might be momentary, while in the other they might be severe and

prolonged.

CHANGES IN THE OSMOTIC PRESSURE OF THE BLOOD FROM THE NORMAL

CONDITION UNTIL NEAR DEATH IN FRESH WATER AND CONCENTRATED

SEA-WATER

Green (705) found that the chinook salmon, Oncorhynchus tschaw-

ytscha, in its migrations to the head waters of rivers for spawning, under-

went a permanent decrease of 17.6 per cent in the concentration of its

blood and yet was able to carry on with vigor the activities of its mus-

cular and nervous system. How far may this decrease proceed before death

takes place? He found that the blood serum of an old weak male salmon

showed a decrease of 32 per cent from the mean A of the blood serum of

normal salmon. This represents the maximum of dilution of which the

blood is capable while still maintaining life. I concluded to investigate

this question in the case of the dog-fish, Mustelus, and at the same time

to study the progressive osmotic changes of the blood from normal life to

death in fresh water and concentrated sea-water. Cessation of breathing

was taken as an index of death.

The following technique was employed: The spinal cord of the animal

was exposed from the dorsal aspect, at the junction of the caudal fin with

the trunk of the body. In this way no large blood vessel was interfered

with. The cord was then destroyed by a probe as far forward as the an-

12 ANNALS NEW YORK ACADEMY OF SCIENCES

terior dorsal fin. Hyde (’08) has shown that all the centers governing

respiration in the skate, though of a segmental nature, are located in the

medulla. Since in the above operation only the posterior two-thirds of

the cord was destroyed, the nervous structures that govern respiration

were not affected. ;

After the cord was destroyed, the tail was removed, the caudal artery

and vein being thus exposed. Blood was then taken for the determina-

tion of its freezing point. After this, the caudal artery was closed with a

small wooden plug covered with absorbent cotton. The animal with the

exception of the posterior part of the body was then placed in the tank

containing the experimental solution. After the desired time, a second

sample of blood was taken for a second determination of its freezing

point. The difference between the first and the second was a measure of

the change in the osmotic pressure of the blood of the particular animal

for the given time and the given solution. In a number of cases as many

as six samples of blood, usually about 5 c.c¢. each, varying with the size

of the fish, were taken from one specimen. The blood was drawn into a

small beaker and placed in an ice bath until the caudal artery of the fish

could be closed and the fish could be transferred back to the water. The

common freezing tube with the side neck for the insertion of an ice erys-

tal was not used on account of the large amount of blood that would thus

be necessary for each determination. A test tube with a smaller diameter

was used instead. Duplicate determinations of the freezing point of the

blood and distilled water demonstrated that the error due to undercooling

must have been small. The experiment was repeated in a number of

cases with uniform results, as will be shown later. Several clean dry test

tubes were kept at hand in order to facilitate the determination of the

freezing point of a number of samples in the shortest space of time. I

found that about fifteen minutes were required for all the steps in the

making of a single determination. On account of necessary interrup-

tions, it was not possible to make the time intervals equal in all cases.

The whole blood, including corpuscles and plasma, was used in the ex-

periments that follow. Hamburger (795), Roth (799) and others have

asserted that the corpuscles are inert in determinations of the freezing

point. Moore (’08) found that the corpuscles of pig’s blood had a A of

from 0.02° to 0.03° lower than that of the serum. Since in all the fol-

lowing experiments A was obtained in the way already indicated, the

error due to the presence of corpuscles would be approximately constant

in cases where the corpuscles were not laked. It would have been prac-

tically impossible to make the frequent determinations of A in these ex-

periments, had I stopped in each case to defibrinate and centrifuge each

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 13

sample of blood. The results are as useful for purposes of comparison as

if the blood had first been defibrinated and then centrifuged. Time was

saved by omitting these procedures and I believe that the results are as

satisfactory. ‘The actual pressure in atmospheres can be easily found by

22.4

multiplying A by Lag (= 12-108).

EFFECT OF FRESH WATER

After the first sample of blood was taken, the animal was placed in a

tank of sea-water, into which fresh water was then run, so that in a few

minutes the water in the tank was fresh. The results of this experiment

were obtained from a series of ten fishes, six males and four females,

ranging from 61 to 82 centimeters in length, and are shown in Table

VII.

TABLE VII.—Changes in the freezing point of the blood of Mustelus canis after

immersion in fresh water until nearly dead

. ‘ Immersion :

Weight in . : Change in A

time in A of blood ot bloed

minutes

pd ed bed peed ped

0.2:

SS ee es

Oubo

—

14 ANNALS NEW YORK ACADEMY OF SCIENCES

TaBLE VII.—Changes in the freezing point—( Continued.)

F ~ : Immersion anieotin

Sex sng i bile g okie A of blood ne Flood

Q 80 1687 0 1.890 0.000

35 1hO 0.13

5d 1.605 0.285

70 1.53 0.36

85 1.39 0.50

Si 7K 1502 0 1.900 0.000

20 1.84 0.06

40 1.74 0.16

59 1.59 0.31

‘of 79 1460 0 1.850 0.000

15 ASSL 0.04

30 1.76 0.09

45 1.635 0.215

65 1.50 0.35

75 1.40 0.45

Q 76 1304 0 1.920 0.000

15 1.87 0.05

40 1.74 0.18

313) 1063 0.29

70 147 0.45

80 1.44 0.48

In averaging the results, we may divide the time into five periods of

twenty minutes each, the first twenty minutes of immersion constituting

the first period and so on. The average change during each period of

immersion is as follows:

Ist twenty minutes = +0.050° i

2nd twenty minutes = +0.133

3rd twenty minutes = +0.265

4th twenty minutes = +0.400

5th twenty minutes = -+0.470

The average of the ten maximum determinations is +-0.408°.

As was found in the series of experiments described on page 9 there

are indications here also of individual variations in the reaction of the

fishes to the changed environment. Figure 1 is a curve which represents

the course of the change in the depression of the freezing point and there-

fore a fall in the osmotic pressure of the blood from the beginning to the

end of the experiment. This curve is derived from the values computed

for each of the twenty minute periods. Certain features of this curve

may be here pointed out. There is a slow change at the beginning of the

experiment. This continues during the first two of the five periods of

immersion. There is then a change in the slope of the curve, indicating

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 15

more rapid changes in the osmotic pressure of the blood. Toward the

end of the time, less rapid changes are again indicated. The ordinate

which determines the last part of the curve is the average of but two

determinations, because most of the animals died before the immersion of

a hundred minutes. The ordinate at D more correctly represents the aver-

age condition at death. That part of the curve from N to D represents

graphically the course of the change in the freezing point of the blood

from the normal condition until near death in fresh water. It may be

thought that the initial slowness of the changes in the osmotic pressure

of the blood is due to the fact that the water is changing from salt to

fresh during this period. The slowness, however, continues longer than

the time required for the

change from salt to fresh +0.40

water. The period of ac-

celeration may be due to

the gradual failure of the +0.20°

defences of the organ-

ism. It is possible that

the first part of the curve Os Wy 7 oy ~~ a

represents changes due = 3 c D E

mrsly fo the entrance of |" 1;_Thene tn 8 of tard of Meta det

water into the blood of

the animal. From this point of view, the second part of the curve might

indicate the passage of dissolved substances such as salts out from the

blood through the limiting membranes of the body into the water out-

side while the outside water continued to pass into the blood. This would

mean, of course, profound changes in the physico-chemical constitution

of the organism. Dakin (’08) found that the maximum change in the

freezing point of the blood of three specimens of Acanthias vulgaris after

immersion in fresh water until near death was 0.465°. Garrey found

the maximum change in the freezing point of the blood of one Mustelus

to be 0.37°. My observations range from 0.27° to 0.50°. That the mag-

nitude of the change is not due to the amount of blood taken is shown

from the records of specimens 1 and 2. The maximum change in case

of No. 1 is .33°, while that of No. 2 was .43°, though six samples of

blood were taken from the first specimen, while but four samples were

taken from the second specimen. Other cases of the kind can be found.

EFFECT OF A CONCENTRATED SOLUTION OF SEA-WATER

The change in the osmotic pressure of the blood from the normal con-

dition until death in a concentrated solution of sea-water was next ob-

16 ANNALS NEW YORK ACADEMY OF SCIENCES

tained. The procedure was in the main as before. The tank in which

the specimens were placed after the operation contained about twenty-

four liters of sea-water. ‘To increase the amount of salts in solution in

this sea-water, about 500 grams of sea-salt were dissolved in a jar con-

taining eight liters of sea-water. This was placed above the tank. After

the normal sample of blood was obtained, the specimen in each case was

placed in the tank of sea-water and the concentrated solution from the

jar was at once run into the tank at one end, the overflow running out at

the other end. At the same time, the various samples of blood were ob-

tained for the determinations of the freezing point, the specific gravity

of the water in the tank was taken. On the whole, the specific gravity of

the solution was 1.034+. Its A was about 2.60°. The A of the sea-

water was about 1.82° and its specific gravity, 1.025. An analysis of the

chlorides in both sea-water and in water of the concentration attained at

the end of each of these experiments showed that the latter contained

about 33 per cent more salts than sea-water. ‘The water in the tank

reached this concentration in about fifteen minutes after each experiment

began. The results are given in Table VIII. Data with regard to eleven

specimens are shown, seven females and three males, ranging in length

from 67 cm. to 84 cm. The sex of one animal was not recorded.

TABLE VIII.—Changes in the freezing point of the blood of Mustelus canis after

invmersion in a concentrated solution of sea-water until near death

Immersion

n ° ;

Sex Le ha in gee time in A of blood ey ae A

g 80 1531 0 1.84° 0.000°

rz 1.30 0.06

30 1.96 0.12

48 1.99 0.15

65 2.06 0.22

(0 2.08 0.24

2 80 1361 0 1.84 0.000

20 1.93 0.09

30 2-01 0.17

50 2.05 0.21

65 2.11 0.27

80 2.15 0.31

rot 75 1247 0 1.88 0.000

25 pRSE 0.06

40 2.00 0.12

50 2.07 O19

75 2.10 0.22

g 67 950 0 1.80 0.000

15 1.87 0.07

30 1,94 0.14

50 2.00 0.20

ioe)

i=)

(ee)

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 13

TaBLE VIII.—Changes in the freezing point—( Continued. )

F . Immersion

Miekent tn time in A of blood

8 $ minutes

Change in A

of blood

Dividing the above time into four periods of twenty minutes each and

averaging the change in the freezing point of all the specimens for each

period, we have the following values:

1st twenty minutes = 0.074°

2nd twenty minutes = 0.125

3rd twenty minutes = 0.190

4th twenty minutes = 0.260

The average of the eleven. maximal changes is 0.24°. Figure 2 is a

curve which represents the course of the change in the blood from the

18 ANNALS NEW YORK ACADEMY OF SCIENCES

normal condition until near the death of the animal in the above concen-

trated solution. Since the curve shows a progressive lowering of the

freezing point of the blood, it should be interpreted as showing an in-

crease 1n the osmotic pressure of the blood. There is a slight falling off

in the effect after an initial sudden change in the freezing point. Toward

the end of the time of immersion the change is more rapid again.

There is good evidence for believing that the dog-fishes in their migra-

tions up and down the coast wander into brackish waters. The organism

must be adapted therefore to withstand a moderate amount of decrease in

the density of the external medium. Under natural conditions, however,

the organism is never subjected to such a concentrated solution as was

used in the present experiment. The concentrated salt solution may act

= , = m p 2S a chemical stimulus upon

0° 20 40 60’ go the arterioles of the gills, caus-

ing them to dilate, and thus

bringing about a greater influx

-0.20° of blood to the gills, from the

capillaries of which the blood

would lose water rapidly by

1.40 osmosis. After the initial

Fic. 2.—Change in A of blood of Mustelus due stimulus, the arterioles would

to immersion of fish in a hypertonic solution :

of sed REP Santi denen: recover their tone, there would

| be a decreased amount of blood

sent to the gills and the loss of water would be retarded. The more

rapid increase in A toward the end of the period is evidently an index of

greater changes in the physico-chemical constitution of the organism.

The above results as to the effect of fresh water and concentrated sea-

water on the osmotic pressure of the blood show that, at the time of death

in fresh water, there is an average rise in the freezing point of the blood

of 0.41° and, at death in the above concentrated solution, a fall of 0.24°,

t. é., in the osmotic pressure a reduction of 21.9 per cent and an increase

of 12.8 per cent respectively. The values probably represent the lethal

limits of departure from the normal constitution of the blood within

which protoplasmic activities of this form take place. I must differ from

Fredericq and others who would classify the elasmobranchs with the ma-

rine invertebrates as to the osmotic relations of their body fluids to the

external medium. This conception would imply that the degree of

change in the osmotic pressure of the blood is equal to the degree of

change in the osmotic pressure of the external medium. In the case of

Mustelus, we have seen that this is not true. It may be, however, that

some relationship exists between the osmotic pressure of the blood of the

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 19

elasmobranchs and modifications in the molecular concentration of the

sea-water. Fresh water has a A of about 0.025°. This is about 1.795°

less than that of sea-water. The concentrated solution had an average

specific gravity of about 1.034+. The A of such a solution was about

_ 2.60°, which is 0.78° greater than that of sea-water. Since the fresh

water produced an average rise in the freezing point of the blood of 0.41°,

what would be the amount of change in the freezing point of the blood in

the concentrated solution if the change in the blood depends upon the

change in the molecular concentration of the external medium? We can

formulate the following proportion: 1.795°:0.41° ::0.78°: X, where X

should equal the change in the blood due to the concentrated solution

should the above relation hold true. X equals 0.177° or approximately

0.18°; but the observed maximum change in the concentrated solution

was 0.24°. There is a difference between the two values of 0.06°. This

would indicate that the relation is only roughly if at all proportional. If

the changes took place to a different degree or in a different manner in

the two solutions, of course any close relationship would be modified.

Furthermore, do these results show any relation between the degree of

change in the freezing point of the blood and the time of immersion? In

the fresh water experiment, eight records were taken between 40 and 45

minutes from the beginning. The average time was about 42 minutes.

The average time of immersion of all ten fishes was 74 minutes. The

average final change in the A of the blood was 0.41°. Therefore in the

following proportion,—74 min. :42 min. ::0.41° :X, X should have

approximately the same value as the A actually observed at the end of

the 42 minute period. X equals 0.23°, the theoretical degree of change

in A. The observed change in the A of the blood of the eight specimens

after 40 to 45 minutes’ immersion in fresh water was 0.18+-°, showing

that the observed change lacked 0.04+-° of being as great as the calcu-

lated change.

~The average time of immersion in the concentrated solution was 69

minutes. Six determinations were made at about 42 minutes from the

beginning of the experiment. If the time relation holds in this case,

then X in the following proportion should be similar to the observed

change in A at the end of the 42-minute period: 69 min. : 42 min. ::

0.24°:X. But X equals 0.146°. The observed change in 42 minutes was

0.16°. One might conclude from the above considerations that we were

dealing here with purely physico-chemical phenomena. It would be haz-

ardous, however, to make any sweeping assertions. If we compare the

changes in any individual with the average changes in the group, the

simple relationships just suggested do not hold. The factors involved

20 ANNALS NEW YORK ACADEMY OF SCIENCES

are so many and to such a degree unknown, that although, in the final

analysis, the plenomena must be physical and chemical, we are not justi-

fied in mainiaining that the relations are definitely quantitative.

Figure 3 represents in a graphic manner the relation of the osmotic

pressure of the blood to the concentration of the external medium as

based upon the conception of a proportional relation existing between the

iwo. The abscissas represent freezing point determinations. The ordi-

nates represent specific gravities of different solutions of sea-water. Pure

A= 0° -0.50° —1.00° —1.50° -2.00° —2.50° -3.00°

17=4D+Y48

1.010

I=%D-¥%S

IV=Y4D+3S8

1.020

V=Sea Water

Vi= 1.030

ViJ= = 1.035

Fic. 3.—Relation of the A of blood to A of different solutions of sea-water. Curve

A-B = A’s of solutions. Curve C—D = A’s of blood

water has a A of 0.00° and a specific gravity of 1.000. The curve A—B

represents the freezing point of different dilutions of sea-water. This

curve is constructed from freezing point data obtained from seven differ-

ent dilutions of sea-water. These were as follows: I, pure water; II, three-

fourths pure water plus one-fourth sea-water; III, one-half pure water

plus one-half sea-water; IV, one-fourth pure water plus three-fourths

sea-water; V, sea-water; VI, concentrated sea-water having a specific

gravity of 1.030; VII, concentrated sea-water having a specific gravity of

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 91

1.034+. The curve C—D represents the freezing point of the blood at

the different concentrations represented by the curve A—B. It is con-

structed by drawing a line through the following points: C —the A of

the blood at the death of the organism in fresh water; N, the A of normal

blood; D, the A of the blood at the death of the animal in the concen-

trated solution, having a specific gravity of 1.034-++ and a A of 2.60°, the

effect of which has been described in this section of the paper; E, the A

of blood of Squalus acanthias in harbor water which has a A of about

#00°.

A further account of this is given later (on page 31). That the oper-

ation of destroying the cord did not modify the results is strongly indi-

cated by the following instance: A large Mustelus canis was operated on

in an attempt to collect a sample of its

urine. ‘The spinal cord was destroyed in

the manner already indicated. The ab- \|

dominal cavity was opened, the rectum |

was ligated and a large glass tube was fas-

tened in the cloaca. The animal was then

placed on a support in the sea-water in

such a way that the head as far back as

the last gill slit was under water. The

abdominal incision was closed and the

surface of the body was kept moist with a

cloth wet with sea-water. At the end of Fic. 4.— Respiratory movements

twenty-four hours the fish was still alive Sg ee et oe

> struction of spinal cord.

and breathing normally. When the peri-

cardium was opened, the heart was seen to be beating regularly. Figure

4 is a record of the respiration at the end of twenty-four hours, the time

record indicating intervals of two seconds. Although the experiment

was a failure as far as its primary purpose was concerned, it proved that

the above operation in itself is no cause of immediate death. Sheldon

(709) has found that Mustelus may live for a week after a similar de-

struction of the cord. Parker (710) has called attention to “the ease

with which this fish resists the adverse effects of operations.”

In a series of earlier experiments, the results of which are given in

Table VI, on the effect of immersion in fresh water on the freezing point

of the blood, I first defibrinated the blood, then centrifuged it, and used

the serum for the determination of the freezing point. About 10 to 15. ¢.

of serum was used for each determination.

In these preliminary experiments, blood was drawn from each specimen

but once. In the case of the specimens immersed in fresh water, the

95 ANNALS NEW YORK ACADEMY OF SCIENCES

oe ow

blood was drawn after they had been immersed for about an hour. The

results were as follows:

TABLE VI.—Showing the depression of the freezing point of the serum of

Mustelus in salt water and after immersion in fresh water for one hour

Serum from fishes immersed

Serum from normal! fishes pnitiroah Gr atemanciane

No. specimen A No. specimen A

1 1 920° ] 1.580°

1 1.950 4 1.460

2 1.805 2 1.595

2 1.950 2 1.595

1 1.947 2 1.540

Average, 1.914° Average, 1.554°

The average rise in the freezing point of the serum of these dog-fish

after immersion in fresh water for an hour is thus seen to be +0.36°.

CHANGES IN THE OSMOTIC PRESSURE OF THE BLOOD BROUGHT ABOUT BY A

RETURN TO SEA-WATER AFTER IMMERSION IN FRESH WATER OR CONCEN-

TRATED SEA-WATER

The above experiments on the effects of diluted and concentrated solu-

tions of sea-water indicate that to cause a decrease in osmotic pressure

with the diluted solutions there must be currents outward through the

limiting membranes of the body; to cause an increase with concentrated

solutions there must be currents inward. Is it possible to demonstrate

these two effects in the same individual? If reversibility is possible, then

after a fall in osmotic pressure resulting from immersion in a diluted

solution of sea-water, the original pressure should apparently be gained

when the animal is returned to normal sea-water. The experiments re-_

ported in Table IX were carried out to test this possibility.

TABLE IX.—Effect on the blood of transference of Mustelus from sea-water to

fresh water followed by subsequent return to sea-water

Sea-water Fresh water Sea-water

Normal A | Duration of f Change | Duration of of Change Amount

of blood immersion oL va from immersion = d from of

in degrees | in minutes ie normal in minutes ee normal reversal

1=1.835 35 1.620° | +0.215° 25 1.685° |+0.15 °| 0.065°

2=1.895 5d 1.655 | +0.240 50 1.785 +0.115 | 0.125

3=1.875 30 1.675 |-+0.200 50 1.760 |+0.115 | 0.085

4=1.905 25 1.665 | +0.240 100 1.785 +0.120 | 0.120

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 93

It is clear that, after immersion in fresh water, we get as before a rise

in the freezing point of the blood. After the return to sea-water, the A is

lowered and the osmotic pressure is increased again; but the normal os-

motic pressure of the blood is not regained, even though the return to

sea-water is as long or even longer than the sojourn in fresh water. This

is shown in the case of the fourth specimen; for after 25 minutes in

fresh water the freezing point had been raised 0.24° above normal, but

when the fish had been returned to sea-water for 100 minutes the freez-

ing point was still 0.12° above normal. Figure 5 shows the changes in

the A of the blood of this specimen. The fish was in fresh water from

F to F* and in sea-water from Ft to 8. The base line represents the

normal A; the abscissas, time in minutes, and the ordinates, the rise in

the freezing point of the blood. At first one might conclude from these

experiments that the limiting membranes were not as permeable in one

direction as the other. A second experiment of this nature will be de-

F 20’ 40’ 60’ 80’ 100’ 120’ 140’

Fic. 5.—Changes in A of blood of Mustelus due to immersion in fresh water followed

by return to sea-water

scribed. In this case, the mixed blood of the two specimens was used for

the determination of the normal A, 1.895°. After 75 minutes’ immersion

in fresh water, there was noted a rise in the freezing point of the mixed

blood of 0.245°. Both specimens were then returned to sea-water and

one died soon after. A determination was made from the blood of the

other 225 minutes after the return, and its A was 0.05° above the normal

A. Although there was an apparent return to the normal condition, the

animal was injured in some way, for it died soon after. In fact, it is not

quite correct to assume that the normal condition of the blood was re-

gained for the last figure given, 7. e., 0.05° is obtained by subtracting the

final A of the blood of this fish from the A of the mixed blood of this fish

and the other which died earlier. The number of molecules and ions in

solution in the blood had decreased after immersion in fresh water. Cer-

tain parts normally present had escaped into the surrounding medium.

The return of the organism to its normal medium did not suffice for the

return to the blood plasma of the normal quantitative relation of parts in

solution.

Concentrated solutions were also tried. Two such experiments will be

24 ANNALS NEW YORK ACADEMY OF SCIENCES

described. In the first, three dog-fishes were used. The A of the com-

bined blood of the three was 1.92°. They were then placed in a concen-

trated solution of sea-water having a A of about 2.60° for forty minutes,

at the end of which time the A of the mixed blood from the three was

%.11°, the freezing point having fallen 0.19°. Then the specimens were

returned to sea-water for eighty minutes, when A was 2.04°, showing that

although the freezing point had risen 0.07°, it still lacked 0.12° of being

normal. In the second experiment, three dog-fishes were also used. The

normal A of their mixed blood was 1.87°. They were placed for sixty

minutes in a tank containing a concentrated solution of sea-water having

a A of about 2.15°. At the end of this time the A of their mixed blood

was 2.00°, showing a fall in the freezing point of 0.13°. The three speci-

mens were then returned to a concentrated solution having a A of 2.60°

for sixty minutes more, at the end of which time the A of their combined

blood was 2.18°, showing a total fall in the freezing point of the blood of

0.31°. Sea-water was then run into the tank for two and one-half hours,

when the value of the A of the blood was 1.98° ; that is in the two hours

and a half after the return to sea-water the freezing point of the blood

rose 0.20°, but was still 0.11° short of its value at the beginning of the

experiment. Thus with neither a hypotonic nor a hypertonic medium did

the organisms regain the normal A after the return to sea-water, even

though they were kept in the sea-water as long or even longer than in the

diluted or concentrated solution.

One other experiment of this nature will be referred to briefly. A

somewhat small stream of concentrated sea-water was passed into the

mouth and out through the gills of a large female dog-fish for 45 min-

utes. The A of its blood fell 0.09°. The small size of the stream possibly

explains the small change in A. A stream of fresh water was then turned

on gradually and A was again taken 60 minutes later. A proved to be

0.16° above its value in the concentrated solution and was even higher

by 0.07° than the normal. The fsh was then returned to sea-water for

60 minutes when A was 0.03° lower than the normal. In this case we

have evidence of an increase in the osmotic pressure of the blood due to a

concentrated external medium. A fall in the osmotic pressure results

when the organism is subjected to a dilute external medium, after which

it rises to the normal condition when the animal is returned to sea-water.

It should be noted that, in changing the concentrated solution to fresh

water, the concentrated solution was gradually replaced by fresh water

and this in turn by the sea-water again. The fish was unusually large,

being 120 em. in length. It rested with its dorsal surface upon a support

out of the water and the stream entered its mouth through a rubber tube

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 25

having an inside diameter of about a centimeter. It seems to me that the

normal A was regained in this case, because the external media produced

but a small degree of departure from it. It is interesting to note that the

maximum change produced in A is about equal to the normal range in A

of normal dog-fish blood as described in the first section of this paper.

The results with the other fishes indicate, however, that osmotic phe-

nomena are complicated by the presence of other factors.

ROLE OF THE GILLS IN THE MODIFICATIONS

Considerable difference of opinion exists as to the part of the body that

is concerned in the osmotic changes in the blood brought about by changes

in the osmotic pressure of the surrounding medium. As stated above,

there are three structures that may be the seat of this phenomenon,

namely, the skin of the body, the lining of the alimentary tract and the

gill membranes. Any one or all of these structures may be conceived to

share in the above processes. The surface of the body of the dog-fish is

covered with a closely associated system of dermal plates forming, with

other structures of the skin, a tough coat through which it would appear

that fluids could pass with the greatest difficulty if at all. The cells of

the intestinal tract are known to exert a selective action on materials

present in the intestine, and therefore we should expect that solutions

more or less concentrated than sea-water which would possibly accom-

pany the swallowed food would be passed out through the cloaca before

osmotic changes of any account would take place. Furthermore, my ob- —

servations indicate that the cesophagus and the cloacal aperture are kept

closed during the greater part of the time, and are probably opened only

during the taking in of food and the getting rid of waste. Therefore the

wall of the gut would not ordinarily be exposed to solutions differing in

density from that of sea-water, even though the whole fish were entirely

immersed in such solutions.

The gills, however, are always freely exposed to the external medium.

Each gill filament contains a fine capillary loop composed of an afferent

vessel and an efferent vessel supported by connective tissue. Covering the

capillary apparatus is an extremely thin epithelial membrane, so that

there are but two thin layers of cells between the water and the blood

stream, namely, the gill membrane and the endothelial wall of the capil-

lary. If the rich capillary supply of the gills be taken into account, there

is in effect a large, broad sheet of circulating blood separated from the

water by an extremely thin membrane known to be permeable to gases.

A priori, therefore, it would seem that the osmotic changes in the blood

described above might take place through the gills.

96 ANNALS NEW YORK ACADEMY OF SCIENCES

The following views have been maintained with regard to this: Bert

(71) gave a minute description of the death of a fresh water fish in salt

water. He described the gills as changing from bright red to dark red in

color, and said that the congested condition of these membranes per-

mitted the blood to transude through them. He found the corpuscles to

be crenated, shriveled and piled up in masses in the capillaries. A tench

suspended in a vessel of sea-water lived a long time if the head was kept

out of the sea-water and the gills were bathed with fresh water. Fred-

ericq (704) stated, “I can in a short time change the proportion of salts

in the blood of Carcinas menas, even to doubling the quantity, if I bring

the animal into water more salty than sea-water. This is due to a pe-

culiarly modified epithelium of the gill membranes by which substances

dissolved in the water can go through the gills easily.” With regard to

the fishes Fredericq said, “Les vertébres aquatiques des poissons se com-

portent tout differement. Chez eux, la branchie, si permeable aux

echanges gazeux de la respiration, semple au contraire constituer une

barrier presque infranchissable aux sels dissous dans l’eau de mer. La

sang des poissons de mer n’est guére plus sale, au gout, que le sang des

poissons (eau douce.” Quinton (’00), however, held the view that salts

as well as water can pass through the external surface membranes of ma-

rine animals. In a later investigation by Bottazzi and Enrique (701), it

was shown that the stomach wall of the mollusk, Aplysia, is normally

impermeable to salts. They concluded that the stomach wall is a semi-

permeable membrane, allowing the water to pass through but excluding

the salts, and proposed the hypothesis that osmotic equilibrium is main-

tained by the liver, functioning as an organ of resorption. Siedlechi

(703) found that the stickleback, Gasterosteus, resisted the effects of sud-

den transitions from salt to fresh water and vice versa. This author held

that the structure of the skin amply protects the organism from the effects

of changes in the external medium. Schucking (’02) showed that salts

left the body of Aplysia, though the mouth and anus were ligated. This

result, together with those obtained by Quinton and Bottazzi, shows that

the surface membranes of Aplysia are permeable. Overton (04) con-

cluded that the skin of amphibians is permeable to water and but shghtly

permeable to salts. Greene (705) from his studies of the Chinook salmon

inferred that in that species all three structures are impermeable. He

accounted for the fall in the osmotic pressure of the blood at the spawn-

ing grounds as being due to absence of food and the poor physical condi-

tion of the fishes. Garrey (705) tied off both ends of the alimentary

canal of Nereis and Chetopterus and found that, if placed in fresh water,

the animals swelled and increased in weight, which showed the permea-

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS at

bility of the body wall to water. Garrey suspended Limulus so that the

gills alone were immersed in a solution of one-half sea-water plus one-half

fresh water. A decrease in the osmotic pressure of the blood took place

which demonstrated the permeability of the gills.

Sumner (’06) inferred that the structure of the skin of most teleosts

was an effective barrier to osmotic exchanges between the tissues of the

fish and the external medium. He devised an apparatus by which the

body was immersed in a solution of one concentration, while the gills were

bathed by water of another concentration. In an experiment with the

carp, Cyprinus carpio, the body of the fish was immersed in fresh water

and sea-water bathed the gills. There was a loss of weight at the end of

the experiment. In the second place, the body of this fresh water fish

was immersed in sea-water and fresh water was supplied to the gills. The

fishes not only continued to live longer than in the first instance, but

there was no loss in weight. The result showed that no osmotic changes

took place through the body membranes of the carp. When the body of

the tautog, Tautoga onitis, a marine form, was immersed in sea-water

and the gills were bathed with fresh water, the fishes died in from two to

three hours. On the other hand, when the gills were supplied with sea-

water and the body was immersed in fresh water, the fishes were appar-

ently not affected. These ingenious experiments of Sumner, in which it

will be noted that the fishes were not injured, contribute strong evidence

for the conclusion that the gills alone are concerned in osmotic changes.

Dakin (’08) called attention to the fact, as did Greene, in the case of the

salmon, that while the contents of the stomach of the lump sucker are

osmotically the same as sea-water, the osmotic pressure of the coelomic

fluid, though separated from the cavity of the intestine by a very thin

wall, is the same as the osmotic pressure of the blood, which is much less

than that of sea-water. He thus proved that the wall of the gut is nor-

mally impermeable to salts except in the processes of nutrition and was

inclined to the belief that the membranes are semi-permeable.

From different points of view, the evidence indicates that the gills con-

stitute the pathway by which the osmotic changes take place. Sumner

alone has attacked the problem directly. Dakin criticised Sumner for not

excluding the gut as a possible factor. I concluded to investigate this

problem in the case of the dog-fish. The following facts justify Sumner’s

conclusion :

The average A of the blood of two dog-fishes immersed in fresh water

for sixty minutes was found to be 1.597°. A male Mustelus canis, sev-

enty-eight centimeters long, was pithed, the body cavity was opened, the

cesophagus was ligated, and the fish was placed on a support out of the

28 ANNALS NEW YORK ACADEMY OF SCIENCES

water. A stream of fresh water was then made to flow into its mouth

and out through its gills. At the end of fifty minutes the freezing point

of the blood of this specimen, whose gills alone were exposed to the fresh

water, was 1.585°. As great a change had taken place in the osmotic

pressure of its blood as had taken place in the case of those whose gills,

intestinal wall and body surface were all exposed to the fresh water.

The operation on the five following specimens was similar to that on

the preceding specimen. <A stream of water was not conducted through

the mouth, but the fishes were so placed on the support that the head as

far back as the fifth gill sht was immersed in the water. In this manner,

the cesophagus being ligated and the trunk of the body being out of water,

the gills constituted the chief structures exposed to the experimental con-

ditions. More than one determination of the freezing point was made in

each case, the conditions of the experiments recorded in Table II being

thus duplicated. These five specimens were also left in the fresh water

until near death. The following, Table X, shows the results obtained

from them:

TABLE X.—Change in the osmotic pressure of the blood of Mustelus canis

caused by immersion of the head alone in fresh water

F : Immersion

No. vere an es ee A, of blood Rise in A

1 80 1290 0 L8a2 +0.000°

15 1.68 +0.17

40 1.52 +0.33

dD Lo +0. 48

2 Au 1148 0 1.92 +-0.000

23 1.75 +0.17

85 1.965 +0.455

3 79 1134 0 1.87 +0.000

45 ere +0.15

85 1.56 +0.31

4 86 2041 0 1.93 +0.000

30 1 Si +0.12

87 1.59 +0.31

5 80 1616 0 1.925 +-0.000

33 1.835 +0.09

93 1.475 +0.45

The maximal changes in the freezing point of the blood in the case of

the specimens belonging to Table VII, in which the three factors, body

surface, intestinal wall and gills were exposed to fresh water, were,

respectively: -+0.33°, +0.43°, +0.445°, +0.37°, +0.27°, +0.50°,

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 29

+0.50°, +0.31°, +0.45°, +0.48°, the average being +0.41°. In the

experiments shown in Table X the maximal rises were: +0.48°, +455°,

+0.31°, +0.34°, +0.45°, the average being +0.407°. There is no

marked difference in the changes in the two groups.

After about thirty minutes’ immersion of the entire body in fresh

water, the average maximum rise in the freezing point of the blood of

three dog-fishes was +0.22°. The rise in two other specimens whose gills

alone were bathed with fresh water for about the same time was +.247°,

an unimportant difference. After the treatment with fresh water, all the

specimens were transferred back to sea-water. The freezing point of the

blood fell in each case. Moreover, the reverse change in the case of those

fishes whose gills alone were exposed to the outside medium was 0.118°,

while for those entirely immersed in fresh water the fall was 0.12°.

The average fall in the A of the blood of three specimens of Mustelus

which were entirely immersed for forty minutes in a concentrated solu-

tion of sea-water having a A of 2.60° was 0.19°. The fall in A of one

specimen with ligated cesophagus, the body surface out of water and the

gills bathed with a hypertonic solution having a A of 3.15° for seventy-

five minutes was 0.23°. The striking fact here is that the fall was no less

in this specimen than in the others, in which all three structures were

exposed to the experimental medium. The greater changes in the second

case was due to the greater density of the external medium and the longer

time of immersion.

In all the experiments described here, it will be noted that as great a

change takes place in the osmotic pressure of the blood when the gills are

the principal structures exposed to the experimental medium as when the

gills, body surface and intestinal tract together are exposed. It is ac-

knowledged that, with the gills, the outside membranes of the head and

the lining membranes of the buccal cavity were exposed to the media.

The surface membranes of the head are, however, excluded, inasmuch as

the non-immersion of a much greater portion of the body surface made

no difference in the results. It is extremely improbable that the lining

membrane of the buccal cavity takes any part in the above changes, be-

cause of its histological structure and blood supply in comparison with

the gill membranes. There is but one conclusion to be drawn. Osmotic

changes which take place in the blood of Mustelus canis when the organ-

ism is surrounded by solutions more dilute or more concentrated than

sea-water take place through the gill membranes.

30 ANNALS NEW YORK ACADEMY OF SCIENCES

OsMOTIC PRESSURE OF THE BLOOD OF AN ELASMOBRANCH TAKEN FROM

BRACKISH WATER

The dog-fishes probably migrate. I am informed by Mr. Denyse of the

New York Aquarium that the spiny dog-fish, Squalis acanthias, is present

in New York waters for a time during the latter part of May and the

first part of June, and then disappears until the autumn, when it returns

to remain until after the New Year. Observations are lacking during the

mid-winter, as no fishing is done at that time, but for a number of weeks

after the fishing is begun in the spring there is no sign of this species.

Mr. Denyse informs me that the smooth dog-fish has been taken at some

distance up the Hudson River. It is very probable then that in their

migrations up and down the coast they pass the mouths of rivers in which

the water must be brackish, especially in the spring time when the rivers

are swollen with the spring freshets. Mr. Denyse has kept a daily record

of the temperature and salinity of the water from New York harbor for

the period from 1903 to 1911. From the monthly averages of that record,

published in the Report of the Director of the New York Aquarium

(712), I have computed the average monthly specific gravity of the har-

bor water for the nine years in question. The results of this calculation

are shown in Table XI.

TABLE XI.—Average monthly specific gravity of New York harbor water for

the years 1903-1911?

Month Specific gravity Month Specific gravity

January &.: 1.0139 July eins: 1.0148

February.... 1.0135 August) <-25 1.0154

March) -e 5. 150021 September... 1.0155

April,..cete.8 1.0100 October...... 1.0148

May vc eiee 1.0120 November ... 1.0147

JUNECS.. 5 ccs 1.0133 December.... 1.0147

Although the migration of fishes is usually stated to be due to a search

for better food conditions and for the purpose of spawning, there is a

possibility that the non-appearance of Squalus in New York waters dur-

ing the early spring is due to the dilute condition of the water. The

density of the water is lowest during April. A considerable rise is noted

in May and June, and it is then that these fishes make their first appear-

ance.

These considerations lead to the question whether the dog-fish is sensi-

* From daily observations made by Mr. W. I. Denyse at the New York Aquarium.

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 31

tive to reductions in the density of the sea-water. Sheldon (’09) has con-

tributed ample evidence of the great sensitiveness of various parts of the

surface of its body to different chemical stimuli. The following instance

is cited merely for the purpose of indicating an interesting problem for

further investigation. At the New York Aquarium a tank about 250 cm.

long, 35 cm. wide and 10 cm. deep was filled with harbor water. A very

small Squalus acanthias about 35 cm. long, taken from harbor water, was

placed in this tank. The brackish water continued to flow in at one end,

while at the other end a stream of fresh water was run in. In a very

short time the dog-fish turned about and swam to the end receiving the

brackish water. It was then placed in the fresh water end, but swam

again into the brackish water. After a number of trials, it was clear that

the dog-fish was sensitive to the fresh water, as it persisted in seeking the

saltier end of the tank. The nasal pouches were then packed with ab-

sorbent cotton and vaseline. The fish was again placed at various places

in the tank, but swam about indifferently or remained stationary. Fur-

ther investigation of this problem was not possible on account of the lack

of proper facilities for experimenting with larger fishes.

The greater number of species of fishes on exhibition at the New York

Aquarium are kept in the harbor water. What is the effect of such brack-

ish water on the osmotic pressure of the blood of the elasmobranchs sur-

viving it? Through the kindness of Dr. Townsend, the director, I was

furnished with a number of dog-fishes, Squalus acanthias, for the pur-

pose of securing an answer to the above question. At the time, the aver-

age specific gravity of the water was 1.015, which would correspond to a

A of about 1.00°. The freezing point of the blood of seven fishes was as

follows:

TABLE XII.—F'reezing point of the blood of Squalus acanthias from New York

harbor water

No. Sex Length in cm, A of blood

1 =e 56 70, °

2 Q 58 1.695

3 Sd 38 1.70

4 me 43 1.685

5 3 41 1.695

6 m4 61 1.69

7 dS 61 1.66

The average A of the seven fishes was 1.69°. This value is 0,18°

higher than the mean A of the blood of Mustelus in sea-water. At New

York, I was unable to get a sample of the blood of Squalus as taken from

32 ANNALS NEW YORK ACADEMY OF SCIENCES

full strength sea-water, 7. e., having a A of 1.82°. These dog-fishes are

brought to the Aquarium from the fishing grounds near Sandy Hook.

The A of the blood of two specimens from Vineyard Sound, Mass., was as

follows:

a—female 56 cm. long, A=1.81°.

b— “* ASy °* — == 187-. Averacei— 181":

This is not far removed from that of Mustelus, which is 1.87°. A larger

number of determinations would probably average 1.87°.

Evidently the normal osmotic pressure of the blood of Squalus under-

goes a reduction, when the fishes are kept in the harbor water. It is also

of interest to see that the blood does not become isotonic with the brack-

ish water in which the fishes are kept. There appears to be a new equi-

librium. If we assume that the blood of Squalus has normally the same

mean A as that of Mustelus, then we can conclude that the A of the blood

of Squalus has risen 0.18°, due to the immersion in brackish water.

Moreover this is the value to be expected, if the change in the osmotic

pressure of the blood bears a definite relation to the change in the osmotic

pressure of the surrounding medium. The following proportion shows

this: 1.795°: 0.82°::0.41°: X, in which 1.795° equals the difference be-

tween the A’s of sea-water and fresh water, 0.82° equals the difference

between the A’s of sea-water and harbor water and 0.41° equals the maxi-

mum change in the freezing point of Mustelus after immersion in fresh

water. X, on the basis of the above theory, should equal the A of the

blood of the fish after immersion in harbor water. But X equals 0.187°,

whereas 0.18° was the observed change in A. It seems to me that the

chief point of interest, however, is that the organism maintains an os-

motic pressure of its blood greater than that of the water in which it is

kept. From what is known of the marine invertebrates, this property of

the dog-fish is a distinct advance. Many of the dog-fishes brought into

the Aquarium do not survive. It is interesting to speculate as to why any

survive. Is it because the limiting membranes of the body are more re-

sistant, or do these membranes become more resistant in response to the

change produced in the osmotic pressure of their blood? On immersion

in fresh water, Squalis did not show as great a reduction in the freezing

point of its blood as was the case with Mustelus. This is shown by the

following table, XIIT:

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 33

TABLE XII1.—Change in A of blood of Squalus acanthias after immersion in

fresh water for one hour

Rise in A atter30] Risein A after

No. Length in minutes in fresh 60 minutes in

— water fresh water

1 56 +0.090° +0.110°

re 58 +0.085 +0.160

3 61 +0.130 +0.260

4 61 +0.090 +0.130

The average change during the first half hour is +0.099° and at the

end of an hour amounts to +0.165°. At the end of the same period in

fresh water the blood of Mustelus had changed about 0.30°. At first it

might be thought that the smaller change in the spiny dog-fish indicates

an acquired immunity to the effects of dilute solutions of sea-water. It is

possible that the limiting membranes of the body have become less per-

meable, thus preventing such a great change as in the blood of Mustelus,

in the experiments with which the change in the external medium was

greater. But, as was claimed above, the A of the blood of Squalus has

risen 0.18°, due to the difference be-

tween the molecular concentration of

sea-water and harbor water. Moreover

the freezing point of its blood has risen

an additional 0.16°, due to the trans-

ference of the fish from harbor water

to fresh water. The total change is

thus 0.34°, or nearly as great as that

taking place in the blood of Mustelus, Fic. 6—Changes in the A of blood of

which was transferred directly from eee a5) | Se cada

sea-water to fresh water. If this in harbor water; B, 30 minutes in

equality of modification in the osmotic = 1°" ©» 6 minutes tm Tresh.

pressure of the blood be true, then it follows that the limiting mem-

branes of Squalus have acquired little or no resistance to the external

medium; for their permeability has not changed. The change in the

osmotic pressure of the blood is still proportional to the change in the

osmotic pressure of the external medium. In Fig. 3, the point E, on line

C—D, represents the A of the blood of Squalus from harbor water, which

has a A of about 1.00°. Fig. 6 shows the changes in A of blood of

Squalus due to immersion in fresh water. It will be noted that the in-

itial A of the blood is .18° above the normal A of the blood in sea-water,

and that although at the end of an hour in fresh water it has risen but

0.16°, yet it is 0.34° higher than the normal A in sea-water.

34 ANNALS NEW YORK ACADEMY OF SCIENCES

Errect oF Loss oF BLooD ON THE OsmoTIC PRESSURE OF THE BLOOD

OF Mustelus canis

In the previous experiments, it will be noted that varying quantities

of blood were taken for the determination of the freezing point. About

five cubic centimeters were used for each determination, and as much as

six times that quantity was taken from many of the specimens. The

criticism might be brought that the loss of so much blood might have

introduced a serious modification in the results, so that what we were

attributing to the difference between the molecular concentration of the

blood and the surrounding medium might in large part be due to loss

of blood. It was necessary therefore to make a control experiment in

which the conditions should be the same as those described on page 13,

with the exception that the fishes should be immersed in sea-water during

the entire period.

Fano and Bottazzi (96) observed changes in the osmotic pressure of

the blood of dogs associated with anemia produced by successive bleed-

ings. They noted that the osmotic pressure of the blood fell immediately

after the bleeding. They explained this as being due to a temporary

lowering of the blood pressure, which causes a diminution in the elimi-

nation of salts ordinarily released in secretions. As a result, those pro-

cesses which are concerned in the formation of lymph are depressed.

The authors suggested that the rise in the osmotic pressure may be due

to the abundance with which globulins are turned into the blood stream.

Globulins passing from the tissues into a less concentrated serum disso-

ciate themselves and separate from the bases with which they are com-

bined and contribute these to increasing the concentration of the blood.

The work of these investigators is hardly applicable here, for the rea-

son that they experimented upon dogs. They took proportionately larger

quantities of blood than were used in the experiments upon the dog-

fishes. Moreover, days and weeks elapsed between the periods when the

blood was tested.

In each of the following cases, after the spinal cord was destroyed, the

fish was placed in a tank of sea-water. Then samples of blood were

taken at intervals for the freezing point determination. Results were

obtained from nine fishes which ranged in length from 56 cm. to 124 cm.

and in weight from 538 gm. to 6482 gm. For each freezing point de-

termination, about five cubic centimeters of blood were taken from the

smaller fishes and ten cubic centimeters from the larger. The entire

amount of blood in mammals is stated to be one-thirteenth of the body

weight. It is also known that a loss of one-half of this amount does not

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 35

TABLE XIV.—Freezing point of the blood of Mustelus canis immersed in sea

water

Weight i

No Sex ene ye Hf Time A Change in A ETB OHIRE of

grams blood used

1 ot 58 038 3.50 P.M 1,82.° 0.000 ° 40

4a 1.82 0.00

520 1.80 +0.02

2 Q 56 538 11.40 a.m. 1.87 0.000 55

2.00 P. M. 1.84 +0.03

aco ie 1.82 +0.05

A553. 1.84 +0.03

3 oti 62 624 3.00 P.M 1.835 0.000 50

1.845 —0.01

1.835 0.00

1.840 | —0.005

4 ‘of 71 936 2.30 P.M 1.84 0.000 32

g.a0 | 1.86 —0.02

AS 1.84 0.00

Gazore 1.88 —0.04

5 g TA) 1474 11.10 a.m 1.93 0.000 54

BESO). 0.0 1:93 0.00

ae | i911 +0 .02

oly | 1.89 +0.04

430) ** 1.88 +0.05

6 ‘of 79 1588 3.20 P.M 1.86 0.000 51

42K): 9 FS 1.90 —0.04

AP ago > 1.90 —0.04

Ge2uie 1.90 —0.04

§n50.5 °° 1.90 —0.04

Z Q 84 1474 9.55 A.M 1.81 0.000 67

10. 2-5 ** 1.83 —0.02

) 0 Sa 1.83 —0.02

Lie 1.86 —0.05

12.00 M 1.85 —0.04

3.00 P.M 1.86 —0.05

8 Q 112 4366 9.35 A.M isk 0.000 18

TORLO 1.84 —0.03

E200, 5 °f 1.85 —0.04

1.30 P.M 1.86 —0.05

FOO" 1.86 —0.05

9 2) 124 649z 3.00 P. M 1.84 0.000 28

5 at: aan 1.89 —0.05

4.00 ‘ 1.90 —0.06

2 Us | aaa 1.92 —().08

5-00: ** 1.92 —0.08

Oral i 1.93 —0.09

FOO, he 1.92 —0.08

[ew ey 1.92 —0.08

Secs 1.92 —0.08

8-50. 9)" 1.93 —0.09

36 ANNALS NEW YORK ACADEMY OF SCIENCES

prove fatal. Hyde (’08) estimated that the blood of the skate is equal

to one-twentieth of its body weight. Even if we assume that the total

quantity of blood of Mustelus is equal to five per cent of its body weight,

in none of the preceding experiments was one-half of the total blood of

the body taken. ‘Table XIV shows the results of the experiments in

which the A’s of the blood were obtained from different samples taken at

intervals from the caudal artery of fishes immersed in sea-water.

In the above series of experiments, more blood was intentionally taken

for each determination of A than was used in the preceding cases. As

indicated above, the object of the experiments was to ascertain the effect

of bleeding on the osmotic pressure of the blood. There was no difficulty

in obtaining blood from any of the fishes experimented upon in the pres-

ent connection. All were alive and breathing regularly at the time the

last sample was obtained. The percentage of the total quantity of the

blood given in each case is only.a rough estimate based on the assumption

that the total quantity equals five per cent of the body weight. In esti-

mating this, the last sample was not included. In reviewing the results,

it is to be noted that there is a slight rise in the freezing point of the

blood of specimens 1, 2 and 5. The remaining six show a fall in the

freezing point. On referring to the accompanying data in each case, it is

found that the rise or fall in A is not related to the sex, length or weight

of the fishes, or to the amount of blood taken. In many of the cases after

the initial change, there is no further modification in A. It is possible

that these small variations from the normal A are indications of the nor-

mal fluctuations in the osmotic pressure as maintained on page 6. The

evidence presented in Table XIV is offered as further support for this

conclusion. Finally, attention is called to the fact that the maximum

changes are slight as compared with those recorded as due to the effects

of fresh water and concentrated sea-water. On the whole we are justi-

fied in concluding that the effects recorded in Tables VII and VIII

were due to the modifications in the molecular concentration of the ex-

ternal medium. Buglia (708) found that simple bleeding produced in the

physico-chemical properties of dog’s blood variations absolutely negligible

as compared with those obtained after injections of salt solutions hyper-

tonic to the blood.

ADDITIONAL CHANGES IN THE BLooD DUE TO ALTERATIONS IN THE

CONCENTRATION OF THE EXTERNAL MEDIUM

CHANGES IN THE ERYTHROCYTES

One might conclude from the above changes in the osmotic pressure of

the blood of fishes exposed to fresh water that the corpuscles were laked

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 34

by the dilution due to the entrance of water into the blood and that this

might be a contributing cause of death. In fact, Mosso (790) working at

Naples made this the basis of his explanation of the death of elasmo-

branchs under this condition. The freezing point of the sea-water from

the Mediterranean is about 26 per cent lower than that of the water at

Woods Hole. The degree of change to which the fishes were subjected

when placed in fresh water was therefore greater in the case of the fishes

with which Mosso worked. This difference may account in part for the

divergence of my results from those of Mosso. Mosso stated that, if the

tail of Scyllwwm was cut off after the fish had been in fresh water for half

an hour, no more blood flowed from the artery, while the heart still con-

tinued to beat. On the other hand, I found that blood might be obtained

from the caudal artery of Mustelus up to the point of death in fresh

water, 7. e., from one to two hours. Mosso also claimed that the serum

remained almost normal at the time of death in fresh water. We have

here noted a profound lowering of the osmotic pressure of the serum.

The results obtained by Garrey (705), Dakin (708) and myself show that

this statement of Mosso’s cannot be correct. Mosso believed the real

cause of death to be due to suffocation. By the action of the fresh water,

the red blood cells go to pieces and clog up the capillaries of the gills,

thereby cutting off the exchange of gases in these structures.

Following up this hypothesis, Mosso studied the osmotic resistance

which the red cells offered to different salt solutions. For example, the

erythrocytes of selachian blood were destroyed in 2.5 per cent solutions

of sodium chloride and the fluid soon became red. Teleosts like Conger

and Murena had a greater resistance and first lost their hemoglobin in a

0.3 per cent NaCl solution. Mosso found that fresh water forms possessed

blood more resistant to salt solutions of different dilution than marine

teleosts, while anadromous fishes like Angutlla and Acipenser possess

blood cells which are especially resistant to dilute salt solutions.

On account of the divergence between my observations and those of

Mosso, I concluded to ascertain whether at the time of death as the result

of immersion of Mustelus in fresh water its corpuscles were laked. This

was ascertained in the following way: The spinal cord of a dog-fish taken

from sea-water was destroyed. About ten cubic centimeters of blood were

drawn from the caudal artery. This was closed, and the fish was trans-

ferred to sea-water which was rapidly changed to fresh. Near the time

of death, the artery was opened a second time and a second sample of

blood was obtained. Soon after each sample of blood was taken, it was

defibrinated. Then each was placed in a separate centrifuge tube and the

two were simultaneously centrifuged. At the end of this process, the

38 ANNALS NEW YORK ACADEMY OF SCIENCES

serum of the normal blood was perfectly clear, while that of the other

showed in some cases faint traces of laking. In other cases it was difficult

to detect any such indication. On the whole, it was thus demonstrated

that there was no marked laking of the corpuscles after immersion of the

fish in fresh water.

In Fig. 7, N represents the osmotic pressure of the blood of Mustelus,

in sea-water; F represents the osmotic pressure of the blood at the time

of death in fresh water; while S represents the osmotic pressure of the

first solution of NaCl in which the blood is laked. In solutions more

concentrated than this the blood is not laked.

I made camera lucida drawings of the corpuscles from both fishes and

observed no measurable differences in size. These corpuscles are oval and

Nok 36 Nos se

Fic. 7.— Diagram showing comparative Fic. 8.—Showing the difference between

A’s of blood of Mustelus in sea-water, the ratios of volume of corpuscles to

N; in fresh water, F; and of saline so- plasma in normal blood, N, as compared

lution, S, in which blood is first laked. with blood taken from fishes after im-

mersion in fresh water, H.

flat, so that, in preparations made of them, the flat surface only would be

observed and there would appear no indication of their thickness. It then

occurred to me to make hematocrit studies of the blood under normal and

experimental conditions. The following results were obtained. The ratio

of the volume of corpuscles to that of serum of normal blood was found to

be about 23 to 77, 7. e., the corpuscles form less than 25 per cent of the

total volume of defibrinated blood. Blood from the same specimen near

death after immersion in fresh water showed a ratio of 31 to 69, that is,

the corpuscles occupied 31 per cent of the total volume of the defibrinated

blood. In determinations made defibrinated blood in a graduated centri-

fuge tube, I found that in normal blood the ratio of corpuscle to serum

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 39

was as 20.5 to 79.5. After immersion in fresh water the ratio was 30.77

to 69.23. Fig. 8 shows this difference. In this figure, N represents the

_ ratio between the volume of corpuscles and serum in normal blood. H

represents the ratio from blood taken from fishes after immersion in

fresh water. Shaded portions represent corpuscles. Considering these

results in connection with those obtained by the use of the camera lucida,

we may conclude that at least some of the corpuscles are swollen after

immersion of the fish in fresh water. The faint trace of laking at the

end of the experiment indicates that at least some of these swollen cor-

puscles cannot withstand the increased pressure of distension by the ab-

sorption of water. These burst and cause the faint trace of laking noted

above. In fact, in preparations made of the corpuscles of a fish that had

died in fresh water, some corpuscles were found broken down.

Since Mosso claimed that the resistance of the erythrocytes of fishes

varied in a general way with the salt content of the blood, I determined

to ascertain the strength of solutions of NaCl which would cause the

laking of the blood of elasmobranchs common at Woods Hole. He found

that the erythrocytes of selachians at Naples were laked by solutions more

dilute than 2.5 per cent NaCl. The sea-water from the Mediterranean is.

isotonic with a 3.8 per cent sodium chloride solution. <A 2.5 per cent

sodium chloride solution is about 34 per cent more dilute than the water

from the Mediterranean. A reduction of 34 per cent in the salinity of

the sea-water from Woods Hole would give a solution isotonic with 1.2

per cent solution of NaCl. So that according to Mosso’s hypothesis the

blood of the Woods Hole elasmobranchs should be laked in a 1.2 per cent

solution of NaCl and in all solutions more dilute than this. I made up

ten solutions of NaCl. The first was a 2 per cent solution, the second a

1.8 per cent solution, the remaining solutions decreased respectively 0.2

per cent, the last being a .2 per cent solution. I tried the effect of these

solutions on the defibrinated blood of the smooth dog-fish, Mustelus canis,

the spiny dog-fish, Squalus acanthias, the sand shark, Carcharias Ivtto-

ralis, and the skate, Raia erniacea. Following are the results of the ex-

periments :

Experiment 1. Squalus acanthias. Male. 29 inches long.

No laking in 2 per cent NaCl to 1.0 per cent NaCl. Faint trace in 0.8 per

cent NaCl. Decided in 0.6 per cent NaCl.

Male. 19+ inches long.

Same results as above.

Experiment 2. Mustelus canis. Male. 29 inches long.

No laking in 2 per cent NaCl to 1.2 per cent NaCl. Faintest trace in 1

per cent NaCl. Decided in 0.8 per cent NaCl.

Male. 29 inches long.

Results same as above.

40 ANNALS NEW YORK ACADEMY OF SCIENCES

Experiment 3. Carcharias littoralis. Female. 48 inches long.

No laking in 2.0 per cent NaCl to 1.2 per cent NaCl. Faint trace in 1.0

per cent NaCl. Decided in 0.8 per cent NaCl.

Experiment 4. Raia erinacea. Female. 20 inches long.

No laking in 2.0 per cent NaCl to 1.2 per cent NaCl. Faint trace in 1.0

per cent NaCl. Decided in 0.8 per cent NaCl.

It is clear that Mosso’s statement is not applicable to the elasmo-

branchs from the Woods Hole region. In the case of the four species here

indicated, there is no laking down to the 1.0 per cent NaCl solution and

even this dilution does not decidedly lake the blood. Bottazzi (706) found

that the blood of elasmobranchs at Naples was more resistant than Mosso

claimed ; the first solution to lake the corpuscles was approximately a 2.0

per cent to 1.75 per cent solution of NaCl. Rodier (799) found that elas-

mobranchs at Arcachon lost the hemoglobin of their corpuscles in less di-

lute solutions than Mosso found to be the case with the elasmobranchs at

Naples. Bottazzi (’06) explained this difference as being due to the dif-

ference in the salinity of the water at the two places. Thus the A of the

sea-water at Naples is 2.29°, while the A of the sea-water at Arcachon is

2.00°. The average concentration of the laking solutions at Arcachon

was 1.46 per cent NaCl. It appears that the corpuscles of the elasmo-

branchs at Woods Hole are much more resistant than those at Naples or

at Arcachon, and more resistant than can be accounted for by the differ-

ence in the salinity of waters. Rodier (’99) believed that the urea in

elasmobranch blood had something to do with the difference in the

hemolytic relations of elasmobranch and teleost blood ; but Bottazzi (799)

found that even in a 6 per cent solution of urea which is almost isotonic

with the blood the corpuscles lost their hemoglobin. He came to the con-

clusion that in addition to the osmotic pressure exerted by the substances

dissolved in the blood each of these substances and especially the sodium

chloride exerted a specific chemical effect upon the corpuscles, thus main-

taining their integrity. I made up a second series of solutions containing

the same percentage of sodium chloride as the preceding series, but in

addition each solution contained as much urea as NaCl, for the reason

that elasmobranch blood contains about the same amount of urea as salts.

In each case the corpuscles appeared at first sight to be more resistant in

the solution of NaCl and urea than in the NaCl solutions. This is as

follows:

Mustelus canis—Corpuscles laked in 0.8 per cent NaCl and 0.6 per cent

NaCl + urea.

Squalus acanthias—Corpuscles laked in 0.6 per cent NaCl and 0.4 per

cent NaCl + urea.

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 41

Carcharias—Corpuscles laked in 0.8 per cent NaCl and 0.6 per cent,

NaCl + urea.

It is of interest to note that the A of the 0.8 per cent NaCl solution is

0.50°, while that of the 0.6 per cent NaCl + urea solution is 0.56° ; that

is, the molecular concentrations of the two are quite similar. The A of

the 0.6 per cent NaCl solution is 0.39° and that of the 0.4 per cent

NaCl + urea solution is 0.38°. In other words, the osmotic pressures of

the two solutions which first cause laking are in each case similar. The

urea in the second set of solutions merely raises the osmotic pressure to

the osmotic pressures of the solutions of NaCl. It must be concluded

that, since the urea takes the place of the NaCl in these dilute solutions,

at least neither the NaCl nor the urea exerts any specific chemical effect

upon the corpuscles. The fact that such a great reduction in the osmotic

pressure of the external medium is necessary before the hemolysis of

elasmobranch blood shows that the integrity of the corpuscle does not

depend upon the equality of osmotic pressures between corpuscle and

plasma. The corpuscles maintain their integrity even though there is a

fall of over 40 per cent in the osmotic pressure of the surrounding

medium. We have seen above that Mosso concluded that the resistance

of the erythrocytes of the blood varied in a general way with the salt con-

tent of the blood. Since the blood of marine teleosts contains very much

less salt than that of elasmobranchs, we should expect that teleost cor-

puscles would be much more resistant than those of elasmobranchs.

‘Mosso found this to be true of the teleosts studied by him. My results

differ in some respects from those of Mosso. The teleosts studied by me

show but a small increase in the resistance of their corpuscles over that of

the elasmobranchs which I examined. This is shown by the following

results :

Experiment 5. Weakfish, Cyonoscion regalis. Female. 30 inches long.

No laking in 2.0 per cent NaCl to 0.8 per cent NaCl. Laking decided in

0.6 per cent NaCl.

Female. 20 inches long.

Same results as above.

Experiment 6. Scup, Stenotonus chrysops. 8 inches long.

No laking in 2.0 per cent NaCl to 0.8 per cent NaCl. Distinct in 0.6 per

cent NaCl. Decided in 0.4 per cent NaCl.

Experiment 7. Killifish, Fundulus heteroclitus. About twenty specimens used.

No laking in 2.0 per cent NaCl to 0.8 per cent NaCl. Laked in 0.6 per

cent NaCl.

Experiment 8. Flounder, Pleuronectes. Female. 15 inches long.

No laking in 2.0 per cent to 0.8 per cent NaCl. Faint in 0.6 per cent NaCl.

Distinct in 0.4 per cent NaCl.

492 ANNALS NEW YORK ACADEMY OF SCIENCES

Experiment 9. Mackerel, Scomber scombrus. 10 inches long.

No laking in 2.0 per cent to 0.8 per cent NaCl. Distinct in 0.6 per cent

NaCl. Decided in 0.4 per cent NaCl.

Experiment 10. Butterfish.

No laking in 2.0 per cent NaCl to 0.8 per cent NaCl. Laked in 0.6 per cent

NaCl.

According to Rodier and Quinton the blood of marine teleosts contains

about 0.6 per cent salts, while that of elasmobranchs has about 1.7 per

cent. I have found that the blood serum of Mustelus contains .86 per

cent Cl, while that of the blood of the flounder, Plewronectes, a marine

teleost, has .53 per cent Cl. The equivalent in NaCl for the dog-fish 1s

1.42 pér cent, while for the flounder it is 0.87 per cent; and yet we have

Solutions

Na Cl.

2.0%

Squalus

Acanthias

Carcharias

Littoralis

Erinacea

Cyonoscion

Regalis

Fundulus

Heteroclitus

Mackerel

Butterfish

Pleuronectes

1.8 “

Lo-

Fic. 9.—Showing the hemolytic effect of different NaCl solutions on the erythrocytes of

four species of elasmobranchs and six species of teleosts. Nos. 1— = elasmobranchs ;

5-10 — teleosts. Blank spaces, no laking; dotted spaces, faint laking; dark spaces,

decided laking.

found that in the spiny dog-fish the first decided laking occurred in the

0.6 per cent solution of NaCl; in the other three elasmobranchs, in the

0.8 per cent NaCl solutions. In three marine teleosts studied the first

decided laking occurred in the 0.6 per cent solutions, while in the other

three species decided laking first occurred in the 0.4 per cent NaCl solu-

tion. Fig. 9 shows the hemolytic effect of different NaCl] solutions on the

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 43

corpuscles of four elasmobranchs and six teleosts. Although on the

whole, teleost corpuscles are laked by a more dilute solution than is the

case with elasmobranch corpuscles, the difference is small as compared

with that given by Mosso. The degree of dilution of the solution which

first lakes the corpuscles in the two cases is not proportional to the degree

of departure from the normal salinity of the blood. Bottazzi and Duc-

ceschi (°96) pointed out that no parallel relation exists between the re-

sistance of the corpuscles and the osmotic pressure of the serum of ani-

mals from the different vertebrate phyla. So we may conclude from the

above results that whatever be the function of the osmotic pressure of the

serum, this is not primarily for the purpose of maintaining the integrity

of the corpuscle so far as the retention of its hemoglobin is concerned.

We have seen that the hemoglobin is retained even though profound

changes in the osmotic pressure of the serum take place. Relatively

speaking, elasmobranch corpuscles have a greater range in the resistance

of their corpuscles than is the case with regard to marine teleosts. They

withstand a greater relative reduction of the osmotic pressure of the sur-

rounding medium, 1. e., serum, before the hemoglobin is lost, than is the

ease of the teleosts. That the death of Mustelus is not due to the laking

of the blood is seen from the above facts. The swelling of the corpuscles,

as shown by hematocrit and centrifuge measurement, is probably a mat-

ter of greater importance. The imbibition of water may interfere with

the gaseous exchanges in the capillaries of the gills. The blood taken in

the centrifuge and hematocrit measurements described here must have

been changed in the gill capillaries and continued to circulate. The gill

capillaries do not become completely clogged up with broken down cor-

puscles as Mosso claimed, as is shown by the fact that the blood used in

all these experiments was taken from the caudal artery. The blood of

Mustelus is first decidedly laked in a 0.8 per cent NaCl solution. ‘The

freezing point of such a solution is —0.50° ; but it has already been shown

that the freezing point of the blood of Mustelus at the time of death in

fresh water is about —1.45°, which indicates a dilution insufficient to

cause laking. It may be, however, that the stream of blood flowing

through the capillaries of the gills is met by an influx of water sufficient

to lake some of the corpuscles as they pass by. The experiments demon-

strate individual differences in corpuscles, since some are laked and some

are not. Whether or not all of the corpuscles are swollen would be diffi-

cult or even impossible to determine. The fact that some corpuscles are

laked, while the great majority retain their integrity, warrants the con-

clusion that not all the corpuscles are swollen.

44 ANNALS NEW YORK ACADEMY OF SCIENCES

CHANGES IN THE SPECIFIC GRAVITY OF THE BLOOD

The method of Hammerschlag was used in the determination of the

specific gravity of the blood of Mustelus under normal and experimental

conditions. After the normal specific gravity of the blood of each speci-

men was obtained, the fish was placed in fresh water until near death.

Each value of specific gravity given below is the average of four or five

determinations.

TABLE XV.—Showing the specific gravity of the blood of Mustelus in sea-water

and after immersion in fresh water

A—Normal specific B—Specifie gravity of blood

gravity of blood in fresh water

No. 1 = 1.0499 1.0483

No. 2 = 1.0448 1.0359

No. 3 = 1.0452 1.0410

Average = 1.0466 1.0417

A fall in the specific gravity of the blood is shown to have taken place

after immersion of the fish in fresh water. The blood is therefore more

dilute.

CHANGES IN THE PERCENTAGE COMPOSITION OF THE WATER AND THE

SOLIDS OF THE BLOOD

It has been shown that profound changes in the molecular concentra-

tion of the blood take place when Mustelus is immersed in fresh water

and concentrated solutions of sea-water. To what are these changes due?

Fredericq (704) concluded that they were caused by absorption of water

into the blood. Centrifuge measurements of the blood of Scylliwm modi-

fied by immersion of the animal in diluted sea-water, appeared to show an

increase in the relative quantity of plasma. Dakin (’08) held the same

view, for he claimed that the modifications in the osmotic pressure of the

blood which took place when Acanthias had been immersed in fresh water

were due to the blood gaining water, and that equilibrium between the

internal and the external medium was established by the gain or loss in

water being counterbalanced by absorption followed by secretion from

the kidneys.

If the modifications in the osmotic pressure of the blood be due merely

to the addition or subtraction of water from the gills, then the gills are

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 45

semi-permeable structures. From what is known of other animals, it is

safe to infer that a reasonable excess of water in the blood would be elimi-

nated by the excretory organs. On the other hand, it has already been

shown that at the time of death the freezing point of the blood has risen

21.9 per cent. If the blood be merely diluted, the decrease in solids,

organic and inorganic, should be proportional to the increase in water.

None of the previous investigations contain references to the percentage

of water in the blood under the experimental conditions here described.

I obtained data with regard to this matter as follows: A certain quantity

of blood was drawn from the caudal artery of a dog-fish taken from sea-

water. After the artery was closed, the specimen was placed in fresh

water for about one hour. The fish was then removed and a second sam-

ple of blood was obtained. Both samples were weighed, placed in a hot-

air bath at a temperature of about 100° C. and dried to constant weight.

The percentage of the dried material was then computed and from this

value the percentage of water was obtained. The results are shown in

Table XVI.

TABLE XVI.—Percentage of water and solids of the blood of Mustelus in sea-

water and after immersion in fresh water

A—Normal blood B—Hypotonic blood |

Water Solids Water Solids

85.39% 14.61% 88.28% 11.72%

87 .04 12.96 89.80 10.20

87.06 12.94 88 .94 11.06

86.76 13.24 88.81 11.19

89.08 10.92 89.69 10.31

84.38 15.62 87 .09 T2.o

82.36 17.64 7.23 12.77

82.69 17.31 85.46 14.54

87 .60 12.40 88.49 11.51

86.65 13.35 87 .36 12.64

87.69 12.31 88 .83 i a a

88.18 11.82 89.26 10.74

89.41 10.59 91.01 8.99

Average = 86.48 % 13.52% 88.48% 11.52%

The average percentage of water in normal blood is found to be 86.48,

while that of the blood of the same specimens after immersion in fresh

water is 88.48, a gain of 2.0 per cent. Is this gain in water sufficient to

account for a rise in the freezing point of the blood of 0.40°? I have

found it necessary to dilute sea-water which has the same osmotic pres-

sure as dog-fish blood, 20 per cent with distilled water in order to get a

46 ANNALS NEW YORK ACADEMY OF SCIENCES

rise of the freezing point equal to that produced in the dog-fishes after

immersion in fresh water. It does not seem that in immersion sufficient

water has been added to the blood to cause the above lowering of the

freezing point. It may, however, be objected that the calculation of the

percentage of water in the two cases does not present the matter in its

true ight. Any addition of water to the blood will separate the cells in

the blood to the same degree that it dilutes the soluble substances in the

blood. The determination of the dry weight of the blood, therefore, would

give a more nearly correct idea of the degree to which the solid substances

of the blood are diluted. Normal blood contains 135.2 parts of dried

material p. m., while the blood from fishes immersed in fresh water con-

tains 115.2 parts of dried material p.m. That is, the blood after immer-

sion of the animal in fresh water contains 14.8 per cent less dried ma-

terial than the normal blood. This means first of all less corpuscles; but

it also means 14.8 per cent less organic and inorganic substances. It is

the inorganic substances in solution which determine in great part the

osmotic pressure of the blood. From this standpoint, then, the dilution

of the blood has caused a reduction of 14.8 per cent in the osmotic pres-

sure of the blood; but such a dilution is insufficient to account for the

rise of the freezing point of the blood actually observed, 7. e., 21.9 per

cent. It must be concluded, then, that this is not altogether due to mere

dilution of the blood by the absorption of water.

CHANGES IN THE NITROGEN CONTENT OF THE BLOOD

A comparison between the organic solids of normal blood and those of

the blood after the immersion of the fish in fresh water would also be an

index of the dilution of the blood; but the amount of nitrogen present is

indicative of the amount of organic material, and therefore I concluded

to make determinations of the nitrogen. I wish to thank Dr. W. Denis

of the Laboratory of Biological Chemistry of the Harvard Medical School

for suggestions as to a modification of the Folin micro-chemical method

for the determination of urea which I used in making the nitrogen deter-

minations. After a sample of normal blood was taken, the fish was placed

in fresh water until near death. A second sample was then drawn from

the caudal artery. Table X VII shows the results of the analysis.

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 44

TABLE XVII.—Nitrogen content of the blood of dog-fishes in sea-water and

after immersion in fresh water

: : 2 . F B—Nitrogen in blood after

L th Weight A—Nit l ; Aids

No, | Tengihin | Weight | A SoeSecin gees | lmmenston jn trosh water,

| ae 72 1077 22.697 18.125

ae 74 1191 22.775 19.145

Be 2 v 69 1049 23.150 19.875

ae 74 1389 23.812 20.825

NNGRAGEY. os ccnp with: 23.109 19.493

The average quantity of nitrogen in the normal blood of Mustelus is

23.109 mg. per c. c., while after the immersion of the fish in fresh water it

has fallen to 19.493 mg. This means that by immersion the blood has

lost 15.6 per cent of its nitrogenous matter. Hemoglobin is a large nitro-

genous component of the blood. It has already been shown that the blood

is not laked by the changes produced in its osmotic pressure by the fresh

water. The hemoglobin therefore cannot have left the blood. The

greater part of the remaining nitrogenous matter in the blood is present

in the proteins of the plasma. It is improbable that they diffuse out

through the gills.

On the whole, the conclusion must be drawn that the dilution due to

the addition of water to the blood will account for a loss of but 15.6 per

cent in the substances in the blood, and also a rise in the freezing point

of but 15.6 per cent.

CHANGES IN THE UREA CONTENT OF THE BLOOD

It has been known for some time that urea is present in unusually large

quantities in selachian blood. Thus von Schreeder (790) found that the

blood of Scyllium contained 2.6 per cent urea, and this was afterward

confirmed by other investigators. Urea is usually regarded as a readily

diffusible substance. Its gram-molecular solution has about the same

osmotic pressure as sea-water, 7. ¢., 22.4 atmospheres. When Mustelus is

immersed in fresh water, will the urea with its high osmotic pressure dif-

fuse through the extremely thin membranes of the gills and the capillary

blood vessels into the fresh water, with a A of but 0.025°? Dr. Denis has

kindly made for me the following determinations of the urea in blood

which I obtained from four specimens of Mustelus under the above ex-

perimental conditions. Moreover, the blood was obtained from the same

fishes and under the same experimental conditions as described on page

—, where my determination of the total nitrogen in the blood is given.

ANNALS NEW YORK ACADEMY OF SCIENCES

TABLE XVIII.—Uread content of the blood of Mustelus canis in sea-water and

after immersion in fresh water for one hour (see Table X for

sex, length, and weight)

Urea in blood after

immersion,

grams p. m, in

fresh water

Urea in normal

ish No., lve a aoa 15.4 12.6

BG IG GED ce ona eto 15.8 1522

Nel sie ce eee 15.0 13.2

See ee Pan co eee 15.6 13.2

Average... ce... 15.45 | 13.05

This means that the blood lost 15.5 per cent of its urea after immersion

in fresh water. The normal blood of Mustelus contains 1.55 per cent of

urea. This has a freezing point of about —0.45°, and 15.5 per cent of

this equals 7.3°. The change in the molecular concentration of the blood

is therefore due to other causes than a diminution in the urea. Moreover,

the diminution in the urea content is approximately the same as that of

the total nitrogen and solids, which, as has been said, indicates in all

probability the changes produced by dilution of the blood due to the ab-

sorption of water through the gills. These results also show that the

maximum change in the osmotic pressure of the blood is due to causes

other than its mere dilution.

CHANGES IN THE SALT CONTENT OF THE BLOOD

It has been concluded that sufficient water has not been absorbed to

account for the lowering of the osmotic pressure of the blood which my

experiments demonstrate to have taken place, when Mustelus is im-

mersed in fresh water. Baglioni (’05) and others have shown that the

blood of the elasmobranchs that they studied contains about 2 per cent of

salts and 2.6 per cent of urea. Although both of these substances con-

tribute to the osmotic pressure of the blood and are readily diffusible, it

is generally held that neither diffuses into the external medium when the

fish is immersed in fresh water. Yet it has been shown in the preceding

experiment that a decrease of 15 per cent in the solids of the blood takes

place. Are the salts decreased to a like amount?

In a first series of experiments the blood was weighed, dried to constant

weight and ashed, and the ash was analyzed for chlorine by the Volhard

method. I wish to thank Dr. George F. White of Clark College and Mr.

W. J. Crozier of the College of the City of New York for valuable advice

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 49

and assistance in the chemical technique here involved. The chlorine in

the blood is an index of the salts present. As a check on the method the

chlorine content of successive samples of blood from five fishes taken from

sea-water was determined. For purposes of comparison the quantity of

chlorine present is expressed in grams per 1000 grams of blood. The

average amount of chlorine in the first sample of blood taken from each

of the five specimens was 6.597 grms. p.m. The average amount of

chlorine in the second sample was 6.668 grms. p.m. The difference is

within the limits of experimental error. The analysis corroborates the

results obtained by measuring the freezing points of successive samples

of the blood of the dog-fish taken from sea-water. In a second series of

experiments, after a normal sample of blood had been taken from each of

five fishes, the fishes were placed in a concentrated solution of sea-water

having a A of about 3.15° for one hour, at the end of which a second

sample of blood was drawn from each specimen. The average amount of

chlorine from the normal blood amounted to 6.249 grams per 1000 grams

of blood. The average amount of chlorine in the blood after the immer-

sion of the fishes in the concentrated sea-water was 7.522 grams p.m.

A gain of 20.4 per cent in chlorine is indicated, which under these condi-

tions probably means a gain of 20.4 per cent in salts. In the third place,

an analysis was made of the chlorine content of the normal blood of

twenty specimens of Mustelus canis. In some cases the blood of two or

even three specimens was mixed for a single analysis. Analyses were also

made of the blood of twenty fishes after immersion in fresh water. The

average quantity of chlorine in the normal blood was 6.098 grams p. m.,

while the average quantity of chlorine in the blood after immersion of

the animal in fresh water for about one hour was 4.638 grams p.m. This

means that the blood had lost 23.9 per cent in chlorine; but in this case

also the loss in chlorine probably means an equivalent loss in salts. It has

thus been shown that on immersion of the animal in a concentrated solu-

tion of sea-water the blood gains in chlorine; on immersion in fresh water

the blood loses in chlorine.

In order to avoid possible errors due to the volatilization of chlorides

through ashing, I decided to make an analysis of the serum of the dog-

fish under the above described experimental conditions.

After the blood was drawn in each case, it was first defibrinated and

then centrifuged. The supernatant serum was drawn off with a volu-

metric pipette. In some cases it was necessary to use the mixed sera of

two specimens for an analysis. Five ec. c. of serum was placed in a volu-

metric flask of the capacity of 100 c.c. About three ec. c. of pure acid was

added. The flask was half filled with distilled water and the contents

50 ANNALS NEW YORK ACADEMY OF SCIENCES

were heated to boiling for about two minutes, after which the liquid was

allowed to cool, the flask was filled to the mark with distilled water and

the contents were shaken. 'The whole was then filtered and 50 c. c. of the

filtrate was used for an analysis of its chlorine by the Volhard method.

The amount of chlorine thus determined was multipled by two, giving

the amount present in the original 5 c.c. of serum, and from this the

amount present in 1000 parts of serum was easily calculated. Table XIX

shows the results of the analysis of the chloride in five samples of serum

taken from seven fishes immersed in sea-water and in six samples of

serum taken from six fishes that had been transferred from sea-water to

fresh water for somewhat over an hour.

TABLE XIX.—Chlorine content of the blood serum of dog-fishes in sea-water

and after immersion in fresh water

ni es Chlorine i

oe acouee from fishes after

Number PeOIMMaORATOr Number immersion in

in grams p. m. Pein bl ke

Weds dicen teadee den 8.778 cats eho ete eee 5.824

RR RN SE er 8.400 » ICT oe SN 6.755

Cel ic ie SE ee 8.246 EE ee A Fe 6.181

eee ee 8.715 Bebe ian Reena ae 6.608

SER ney rapte Fate 9.079 AR ty ware 6.7384

ling Oeste aera. apres er 6.433

Average..... 8.643 Average.... 6.422

The average in the case of the first group is 8.643 p. m., while that for

the second group is 6.422 p. m., a difference of 25.7 per cent, representing

the loss of chlorine resulting from the immersion.

The greater percentage of Cl in the serum than in the blood is due to

the fact that practically all the chlorides of the blood are dissolved in the

serum. The significant feature of the two groups of analyses is that the

percentage loss in chlorine is approximately the same in the two cases.

The results warrant the conclusion that after immersion in fresh water

for about an hour, 7. e., until near death, the blood contains about 25 per

cent less chlorine in solution than is the case with normal blood. This

means that the salt content of the blood is less than the urea and other

nitrogenous substances. If there had been no loss of salts by diffusion,

then there should have been a decrease of but 15 per cent in the salts at

the end of the period of immersion in fresh water. We are driven log-

ically to the conclusion that the excessive diminution in the salts of the

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 5]

blood takes place by diffusion through the gills and that the gill mem-

branes become permeable to them.

REGULATION OF THE OsMoOTIC PRESSURE OF THE BLOOD oF MUSTELUS

A constant osmotic pressure of the blood is regarded as necessary for

the normal activities of cells and tissues of the higher forms. The kid-

neys are recognized as being primarily concerned in maintaining this

constant pressure. Their activity in this connection will be considered

later. In addition to the kidneys, it has been pointed out by Buglia (709)

that the tissues take part in this regulation. Bugha found that injec-

tions of hypotonic salt solutions into the circulation of a dog produced

little effect on the molecular concentration of the blood. He concluded

that the excessive water disappeared with astonishing rapidity from the

blood plasma by entering the cells or tissues. In this way the normal

osmotic pressure of the blood was maintained. Japelli (’06) found after

intravenous injections of hypotonic solutions of sodium chloride into the

circulation of the dog, that the muscles took up water from the blood,

thus exerting a regulative action on the osmotic pressure of the blood.

When Mustelus is immersed in fresh water, its tissues are bathed by di-

luted blood. Is there any evidence of an attempt on the part of the tis-

sues to maintain the normal osmotic pressure of the blood by taking up

water from the hypotonic blood which bathes them? Various organs,

namely, the brain, heart, kidney, spleen and muscle, were removed from

several dog-fishes which had been in sea-water. The same organs were

removed from other fishes that had been immersed in fresh water until

near death. Each organ was placed on filter paper, the heart and brain

being cut open, and the other organs being cut into small pieces. All

free fluids were removed with filter paper. Each organ was then weighed

and put at first into a hot-air bath at 100° C. for a time and then into a

dessicator over sulphuric acid. A partial vacuum was made by withdraw-

ing air by means of a filter pump. When the organs were dried to con-

stant weight, the percentage of water in each case was calculated. The

results of this experiment are shown in Table XX.

ANNALS NEW YORK ACADEMY OF SCIENCES

TABLE XX.—Percentage of water in various organs of the dog-fish when the

animals were taken from sea-water and after they had been

immersed in fresh water for about two hours

Brain Heart Kidney Spleen Muscle

Norm. | Hypo. |; Norm.| Hypo. || Norm.| Hypo. || Norm. | Hypo. || Norm. | Hypo.

Se}

is)

MWOOUNNWNIBHUNDOOHAS

ay)

Eig

WMD WH OMWNRARWOOHH |:

WAWOHWRODUSCNWARAROONN:

MON MARDWHNIHONBRUIDONWO

CO CODE NOCH ONOMNMWWMDOO

EHR OO NTOTCONICOCO HRN RORDROADre S

- 0

- oS

mon

[S)

Averages, 79. . ; 84.5 || 79.3 | 82.5 || 77.8 | 79.8.1} 79.4 | 81.7

An examination of the table shows that the organs of the animals that

had been immersed in fresh water contain more water than those of nor-

mal animals; the various tissues show the following increases: Brain,

4.1 per cent; heart, 4.0 per cent; kidney, 3.2 per cent; spleen, 2.0 per

cent; muscle, 2.3 per cent. The average percentage of water in normal

tissues was 79.3 per cent, while in the fresh water specimens it was 82.4

per cent, an average gain of 3.1 per cent. It thus seems certain that the

tissues take up a certain amount of water from the blood, when this is

made hypotonic by the immersion of the fish in fresh water. From this it

must be concluded that the tissues of an animal constitute a mechanism

for the regulation of the osmotic pressure of the blood.

It was stated above (p. 51) that the kidneys are concerned in the regu-

lation of the osmotic pressure of the blood of higher forms. Mammals

after drinking a great amount of water secrete a greater amount of urine

than usual. This urine is also more dilute than normal urine. Whereas

in man urine usually has a specific gravity of 1.020, the dilute urine may

have a specific gravity of 1.002 (Hammarsten). Overton found that

water absorbed through the skin of the frog is excreted by the kidneys.

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 53

Fischer (710) found that if a ligature was tied about a frog’s leg and the

animal was put into fresh water the leg became greatly swollen because

of the absorption of water. The circulation of the blood and lymph being

stopped by the ligature, the kidneys could not pass off the excess of water.

Will the kidneys of Mustelus act in the presence of the diluted blood in

such a manner as to conserve the normal osmotic pressure of the blood ?

Observations were made by Dr. W. Denis and the author on the quanti-

tative secretion of the urine of Mustelus. The method of collection has

been described by Denis (712). The average secretion of urine per 24-

hour period was 21.6 c.c. The urine does not appear to be eliminated

constantly but periodically, as in the case of the higher forms. Since

Mustelus dies in about an hour after immersion in fresh water, no at-

tempt was made to collect the urine during such a short period. The

effect of four other solutions, however, the osmotic effects of which have

already been shown, were tried: namely, sea-water; concentrated sea-

water having a A of 2.60°; three-fourths sea-water plus one-fourth fresh

water; and one-half fresh water plus one-half sea-water. For the first

few hours after immersion the average secretion per hour for four speci-

mens in sea-water was 0.4 c. c. urine; in the concentrated solution of sea-

water, the average secretion of two fishes was 0.2 c. c. urine; in the solu-

tion of three-fourths sea-water plus one-fourth fresh water, the average

secretion of two fishes was 1.2 ¢. c. urine; and in the solution of one-half

sea-water plus one-half fresh water, the average secretion of five fishes

was 1.4 c.c. urine. The results show that, in the concentrated solution

of sea-water, less urine, and, in the dilute solutions, more urine is secreted

than in normal sea-water. There is no doubt then that the immersion of

the fish in modified solutions of sea-water with the resulting changes in

the molecular concentration of the blood, causes an immediate reaction

on the part of the kidneys.

The nature of the urine thus secreted as compared with normal urine

is shown by the results of the following experiments: The A’s of the urine

collected from three dog-fishes immersed in sea-water were respectively

1.69°, 1.70° and 1.77°. The average of these values is 1.72°. These

results indicate that it may be hypotonic and not isotonic with the blood.

Bottazzi (706) stated that elasmobranch urine is isotonic with the blood,

although some of the results given by him indicate that it is hypotonic.

The A of the urine collected from a dog-fish immersed in a solution of

one-half sea-water plus one-half fresh water for about four hours was

1.61°. Furthermore, the specific gravity of two samples of normal urine

was found to be 1.034 and 1.037, while that of two samples of urine col-

lected after immersion of two fishes in one-half sea-water plus one-half

54 ANNALS NEW YORK ACADEMY OF SCIENCES

fresh water was found to be respectively 1.030 and 1.026. The specific

gravity determinations were made on fresh urine. One sample was large

enough for the use of the hydrometer. The other determinations were

made with the pycnometer. Denis (712) records the normal urine of one

Mustelus canis as 1.082.

Finally, the average amount of chlorine in two samples of normal urine

was 9.1812 gms. Cl per 1000 c. c. urine, whereas the chlorine in the urine

of two other fishes immersed in a solution of one-half sea-water plus one-

half fresh water for about four hours amounted to 6.9517 gms. Cl per

O00 4c) c.

It must be concluded, therefore, that the urine collected from fishes

immersed in diluted sea-water is more dilute than normal urine. What

is the concentration of the blood under these experimental conditions?

Are the activities of the kidneys such as to conserve in any way the os-

motic pressure of the blood? In the specimen whose urine had a A of

1.61° after about four hours’ immersion in one-half sea-water plus one-

half fresh water, the A of the blood was 1.64°. The blood is shghtly more

concentrated than the urine; but it has already been shown that there is a

great reduction in salts in the urine of the fish immersed in fresh water.

This leads to the conclusion that the salts are not being excreted, but are

being held back by the excretory organ. The kidneys are acting to main-

tain the osmotic pressure of the blood by the excretion of water. The

problem is complicated by the fact that constantly water is coming into

and salts are leaving the blood through the gills.

PRESENCE OF SALTS IN THE EXTERNAL MEDIUM AFTER THE IMMERSION

OF FISHES IN DISTILLED WATER

If salts diffuse from the blood out through the gills, an analysis of the

diluted sea-water in which Mustelus is immersed should reveal the pres-

ence of these salts. To test this I made the following experiment:

A male dog-fish 60 em. long was pithed and a bolus of oiled cotton was

placed at the entrance of the stomach to prevent regurgitation of the

stomach contents. The fish was then immersed in sea-water. This was

gradually changed to fresh water in about five minutes, when the fish was

removed, thoroughly washed in fresh water and placed in a jar containing

two liters of distilled water. No urine was allowed to enter the jar. Air

was bubbled into this water during the course of the experiment. The

fish was near death when taken out of the jar forty-five minutes later.

The chlorine in one-half of this water was then determined in the follow-

ing manner: The sample was boiled down to 200 c. c. and filtered ; 20 ¢. c.

of the filtrate was analyzed for chlorides by the Volhard method. This

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 55

was repeated five times. The average results equaled .0253 parts chlorine

per 100. This is more than twenty times as much Cl as is present in the

fresh water of Woods Hole. In a second experiment carried on in the

same way, two fishes were immersed in four liters of fresh water. After

death, the water was evaporated down to the volume of one liter and

aliquot portions of this showed the presence of .68 gms. Cl in the water,

or .01708 gms. chlorine per 100. This value is nearly twenty times the

* amount of chlorine found in the fresh water. In these experiments there

were only two possible sources of the chlorides. One was the skin; but

in view of the thorough washing of the external surface in fresh water

this does not appear to me a probable source. The other was the gill

membranes. Diffusion through these structures seems to afford the

logical explanation of the presence of the salts in the water of immersion.

EFFECTS OF IMMERSION IN FRESH WATER ON BLOOD PRESSURE,

RESPIRATION AND Heart Brat

The effects of immersion on blood pressure are not so marked as on

respiration and heart beat. In general, however, it can be said that from

the time the fresh water is turned into the tank the blood pressure falls.

The variations in blood pressure were recorded in the following manner :

After a fish had been pithed, the tail was removed and a canula filled

with a solution of sodium carbonate was inserted in the caudal artery.

The fish was then placed in a tank of running sea-water. The canula was

then connected with a recording tambour also filled with the sodium

carbonate solution. The lever of the tambour recorded the blood pressure

and the heart beats on a slowly moving drum. After a normal record

had been obtained the fresh water was turned on. The fall in blood pres-

sure varies in individuals, and appears to be correlated with respiratory

rate and heart frequency. The blood pressure rises at times, but soon

falls to its former level. This momentary variation is also connected with

the variations in the heart beat. In three experiments at the time of

death in fresh water, i. e., when respiration had permanently ceased, there

was a fall in blood pressure of about 30 per cent from the normal. Fig.

10 shows the change in blood pressure of Mustelus from the time of im-

mersion in fresh water at 9.50 a. M. until its death at 11.15 a. M.

Immersion in fresh water results in the gradual cessation of respira-

tion. For example, in one case there were 59 respirations per minute at

the time when the sea-water was changed to fresh water; there were 61,

four minutes after; 60, eight minutes after; 56, twenty-two minutes

after ; 46, thirty-one minutes after; 33, thirty-seven minutes after; 31,

forty-two minutes after; 43 very feeble respirations, forty-eight minutes

56 ANNALS NEW YORK ACADEMY OF SCIENCES

after; 14, feeble, at fifty-five minutes; 8, very feeble, at sixty-seven min-

utes; after which the experiment stopped. In some cases, the diminu-

tion in respiratory rate toward death was still more marked. Moreover,

the respiratory movements gradually became less forcible. Toward death,

they were very weak and consisted of but gentle movements of the gill

covers, to the eye ineffective as compared with normal respirations. The

respiratory movements at times ceased for a period altogether and then

suddenly broke forth with rapidity and force, soon fading, however, to

BC ea

Wy Ww NAS \f

SAIS AIR ADA Ae 4

Fic. 10.—Showing changes in blood pressure of Mustelus canis due to immersion in

fresh water

complete cessation. Respiration ceases before the heart stops. Now and

then in normal respiration slightly convulsive movements of the gill ap-

paratus is observable. These have been noted by Hyde (’04-08) in the

case of the skate. She drew the conclusion that these movements consti-

tute an attempt on the part of the fish to force a sudden strong current

of water through the gill apertures, the effect of which is to clean the gill

membranes of any foreign matter collected from the sea-water during the

course of normal respirations. After the fresh water was turned on, one

of the commonly observable effects consisted of violent respiratory spasms

accompanied by movements of the whole head. These spasms increased

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS BY

in intensity and frequency until nearly an hour after immersion, and

then gradually and irregularly declined in number and strength. These

respiratory movements are possibly modifications of increased intensity

of the normal gill-cleaning movements mentioned above. It is also pos-

sible that both have fundamentally the same cause but that the stimulus

is more intense when the fish is immersed in fresh water. Foreign ma-

‘

voll

Fig. 11.—Showing the change in the character of the respirations during an hour after

immersion of Mustelus in fresh water. Irregularities represent spasmodic respira-

tory movements.

terial on the surfaces of the gill membranes prevents the normal func-

tioning of these structures and tends toward asphyxiation. The changes

in the gill membranes brought about by immersion of the fish in fresh

water are accompanied by the same convulsive gill movements.

There is considerable variation in the respiratory modifications in

individuals, but the above mentioned features were observable in most

58 ANNALS NEW YORK ACADEMY OF SCIENCES

fches studied. At times, the respiratory rate and heart frequency are

equal; but they appear to be little correlated. After immersion in fresh

water, there is rarely any sign of relation between the two rates. Fig. 11

shows the change in the character of the respirations due to the immer-

sion of Mustelus in fresh water.

5 RARITIES

Fic. 12.—Showing changes in heart beat of Mustelus due to immersion of fish in fresh

water. Irregularities represent spasmodic cardiac movements

The effect on the heart beat of the immersion of Mustelus in fresh

water was studied directly in the following experiment, of which Fig. 12

is a record: A female Mustelus canis 79 cm. long, 1247 gms. in weight,

was pithed and an opening about 1 cm. square was made in the pectoral

arch over the pericardial cavity. A fine hook was attached to the tip of

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 59

the ventricle and connected by a thread to a lever recording on a slowly

moving drum. With its dorsal surface downward the fish rested on an

inclined support in a tank of sea-water so that the head and gills were

under water. No sea-water entered the pericardial cavity. After the

normal heart beat had been recorded for a few minutes, a stream of

fresh water was turned into the tank, and a record was made of the

changes in the heart beat for 80 minutes. During the period that the

fish was immersed in sea-water, the heart was beating at the rate of 50

per minute. The rate changed to 59 per minute during the second minute

after the fresh water had been turned on, and then gradually fell as fol-

lows: 6th minute, 45 beats per minute; 12th minute, 28 beats; 16th min-

ute, 13 beats; 18th minute, 11 beats, 22nd minute, 9 beats; 30th minute,

‘10 beats; 35th minute, 6 beats; 44th minute, 14 beats; 51st minute, 12

beats; 58th minute, 13 beats; 70th minute, 15 beats; 75th minute, 14

beats; 80th minute, 12 beats. Accompanying the early diminution in

heart rate, there was an increased amplitude of contraction. In fact, the

amplitude of the beat varied for a time inversely with the rate. The in-

creased amplitude and slower rate began to be marked about the 14th

minute after the fresh water was turned on, coinciding somewhat with

the time at which the water was entirely fresh, being most marked be-

tween the 30th and 40th minutes. A diminishing respiratory rate accom-

panied this increased amplitude of contraction. The forcible and slow

heart beat gradually failed after respiration ceased. Soon after respira-

tion ceased, the heart beat showed great irregularity in the time taken by

each contraction. At the end of an hour, the amplitude of contraction

was about equal to that of the normal heart beat but the rate was only

about one-fourth as great. After this, the extent of the contraction di-

minished gradually, although by stimulating the heart mechanically it

increased for a time. About 70-80 minutes after immersion in fresh

water and about twenty minutes after respiration ceased, the heart beat,

although slow and regular, was very weak and was probably not effective

enough to drive the blood through the gill capillaries with sufficient

rapidity to maintain life. This agrees in the main with Mosso’s (90)

observation.

Another related feature accompanying the change in cardiac activity

were the respiratory convulsions similar to those mentioned on page 57.

This is strongly suggestive of an associated action of the bulbar cardiac

and respiratory mechanisms which exists in the mammal. The gill covers

became greatly contracted and simultaneously the heart was slowed and

greatly dilated. The inhibition of the heart in diastole and the character

of the recovery as shown in Fig. 12 suggests that the cardiac spasm is

60 ANNALS NEW YORK ACADEMY OF SCIENCES

possibly an instance of reflex inhibition of the heart beat due to the

cardiac-inhibitory center being stimulated by impulses from sensory

nerves ; but the heart gradually recovered the force and rate it had prior

to the convulsive movement, and the respiratory spasm ceased.

During the twenty minutes after immersion, there occurred about ten

very marked respiratory spasms with their accompanying effects on the

heart. ‘Twenty or more took place during the second twenty minute

period. After this they diminished in number and force, ceasing almost

entirely about the 70th minute. Some respiratory convulsions took place

MIDI SIN JTWN

2 /

RANAAN abn

Ny \/ VM) V/ f \/ / /

[\ f

PNATAVANATACATATAUAUAVAVAULUAAUATANAULTAAAUATATANL

WAI AANA

NEG CASS

FIG. 13.—Showing changes in blood pressure and heart beat of Squalus due to transfer-

ence from harbor water to fresh water from 11.06 A. M. to 3.56 P. M.

after regular respirations had ceased. Fig. 12 shows the changes in the

character of the heart beat of this specimen.

The case with Squalus acanthias studied at the New York Aquarium

during the early winter, December, differs from that of Mustelus. The

water in which these fishes had been kept had a temperature of about

12° C. Moreover, the fishes, as has already been described (p. 32), had

been living in a diluted sea-water for some time. The rate of the heart and

of the respiration was much lower than in the case of Mustelus in summer.

Moreover, it was observed that the fishes lived longer after the fresh water

was turned on than was the case with Mustelus. One specimen was under

observation for five and one-half hours, during which a record was kept

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 61

of its blood pressure. This fell 30 per cent from its value at the begin-

ning of the experiment. The fall was gradual. The heart was beating at

the rate of 16 per minute at the beginning of the experiment and 8 per

minute at the end. Respirations were at the rate of 14 per minute at the

beginning and ceased about four hours after fresh water had been turned

on. Fig. 13 shows the character of the changes in blood pressure and

heart beat in this specimen. The absence of the spasmodic respiratory

movements is apparent. Other spiny dog-fishes at the New York Aqua-

rium did not withstand the immersion for so long a time. But in every

case with Squalus the changes in blood pressure, respiratory rate and

heart beat took place much more slowly than was the case with Mustelus.

There are two factors that may have a causal connection with this differ-

ence. In the first place, because of its immersion in diluted sea-water

during its stay in the aquarium, Squalus may have acquired a certain kind

of immunity to the freshened water, so that a transition to wholly fresh

water would not have such a quickly fatal effect as in the case of Mustelus.

That the factor is not altogether the change in the osmotic pressure of

the blood is suggested by the fact that after about an hour’s immersion in

fresh water the A of the blood of a number of spiny dog-fishes, as has

been shown on page 33, was about the same as that of Mustelus, although

it must be confessed not quite so high. In the second place, the tempera-

ture of the water in which the spiny dog-fishes had been kept as well as

that of the fresh water in which the fishes were.immersed in the experi-

ment was low, the latter being 12° C. Metabolism was probably at a low

ebb, and therefore chemical and physical changes would take place more

slowly.

In publishing blood pressure tracings from the Chinook salmon, Greene

(705) states that certain waves, which are shown, are due to the rhythmi-

eal effect of respirations on the blood pressure which also records heart

beats. A series of waves similar to those published by Greene are now

and then found in the normal blood pressure tracing from Mustelus as

shown by Fig. 10-1. In this case, it is certain that the waves are not all

synchronous with the respirations, nor have the respirations anything to

do with them. On the contrary, these are evidently Traube-Hering waves

and probably due to rhythmical variations in the tone of the vaso-motor

center. Almost as many respiratory movements take place during each

of these rhythmical periods as there are heart beats recorded. It may be

that the waves in this case are due to the destruction of the spinal cord.

All indications of them cease when the animal is placed in fresh water.

That the heart action is not altogether dependent upon respiratory

activity is shown by the fact that the heart continues to beat long after

62 ANNALS NEW YORK ACADEMY OF SCIENCES

respiration has ceased. The respiratory rate may suddenly increase tem-

porarily, while the heart rate is steadily declining. On the other hand,

the heart rate may become more frequent while the respiratory rate is

declining.

Parker (710) stated “that the rate of gill movement in the dog-fish

depends upon the momentary state of movement of the animal. When

resting, they vary from 35 to 40 movements per minute. When swim-

ming slowly, they respire 50 to 55 times

per minute. In vigorous swimming, the

rate is doubtless still more rapid.” The ac-

companying figure, Fig. 14, is a record of

the respiratory and cardiac activity taken

simultaneously, and shows that while the

respiration rate is 52 per minute the heart

rate is but 40 per minute. At times, the

two rates may be equal; but this is rather

| | the exception, so far as my observation

goes. The two seem to be independent.

| We may conclude that the respiratory

convulsions described above do not produce

cardiac spasms as shown in Fig, 12, but,

on the contrary, the two processes occur

simultaneously and both have the same

cause.

We know that the density of the water is

changing constantly, but these spasmodic

movements occur long after the water be-

comes fresh. The movements cannot be

Fic. 14.—Comparative rate of res- due to the stimulus of changing external

piration and heart beat in Mus- : = FP

telus im searvater. Upper trac. Ceusity..) We know, too mthat the: osmouc

ing, heart beat, 40 per minute; pressure of the blood is changing con-

below this, respiratory, rate, 52 : .

sso anit stantly ; indeed, the change continues long

after the water has become fresh and con-

tinues to change up until the death of the animal. Owing to swelling

corpuscles, dilution of the blood and alterations in the gill membranes,

it is probable that the blood fails to get oxygenated and that its CO, in-

creases in quantity. In fact, the blood drawn from the caudal artery at

the end of the experiment has a dark appearance, brightening upon ex-

posure to the air. If thus the blood becomes profoundly venous, laden

with CO, it would flow through the respiratory center and cause spas-

modic contractions of the respiratory muscles.

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 63

DISCUSSION

The changes in the osmotic pressure of the blood of Mustelus canis

after immersion in diluted and concentrated solutions of sea-water have

been shown in the preceding pages. It has been shown that this dog-fish

differs from the marine invertebrates in that the osmotic pressure of its

blood does not become equal to that of the surrounding medium, when

this differs in its concentration from the sea-water. Moreover, when a

considerable change has been produced in the osmotic pressure of the

blood of Mustelus by immersion in a modified solution of sea-water, the

normal osmotic pressure of the blood is not regained on the return to

sea-water. In this respect, also, the elasmobranch differs from the marine

invertebrate.

The elasmobranchs differ also from the marine teleosts, the osmotic

pressure of whose blood is between one-third and one-half that of the ex-

ternal medium, and whose blood maintains a constant osmotic pressure

despite marked changes in the osmotic pressure of the external medium.

The elasmobranchs cannot in truth be termed either poikilosmotic or

homoiosmotic animals. It has been shown that the freezing point of the

blood rises about 0.40° C. on immersion in fresh water until near death,

and 0.18° C. on immersion in sea-water diluted with an equal volume of

fresh water, having a freezing point of —1.00°. In both cases the

change in the osmotic pressure of the blood is about one-fourth of the

change in the external medium. In concentrated sea-water having a

freezing point of about —2.60°, or about 0.80° below that of sea-water,

the osmotic pressure of the blood increases about one-fourth as much as

the change in the external medium. In these three cases, the change in

the osmotic pressure of the blood though not equal to the change in the

osmotic pressure of the external medium, yet bears a rather constant

ratio to the external change.

This appears to be the index of a certain degree of independence on

the part of the animal of the osmotic pressure of the external medium.

From this point of view, it would be correct to consider the elasmo-

branchs as occupying a position midway between the marine teleosts and

the marine invertebrates as to the relations of the osmotic pressure of

the internal fluids of the body to the external fluids in which these forms

live. |

The problem, however, calls for further analysis. In the first place, it

is necessary to know what parts of the elasmobranch body are concerned

in the osmotic changes which cause the death of the animal in the modi-

fied external medium. Evidence has been presented showing that there

64 ANNALS NEW YORK ACADEMY OF SCIENCES

are two gateways between the internal media and the external medium,

namely, the gill membranes and the kidneys. After immersion of Mus-

telus in diluted sea-water, of course all movement of liquids in the case

of the kidneys must be from within outward; in the case of the gill

membranes the movement may be in both directions.

Information has been gathered from the experiments as to the condi-

tion of the blood due to immersion of the fish in the modified sea-water.

In fresh water, the specific gravity of the blood is less than normal; the

solids are 14.8 per cent less; the nitrogenous substances 15.6 per cent

less; the urea content has decreased 15.5 per cent; the chlorine content is

25.7 per cent less and the osmotic pressure has fallen 22 per cent. When

hypertonic saline solutions are introduced into the blood system of an

animal, one of the first reactions is the withdrawal of water from the

tissues into the blood; but the present condition is the reverse. The

blood is deficient in salts. The tendency of the tissues will be to absorb

water from the blood. Evidence of this reaction has been presented on

page 52. But sufficient water cannot be taken into the tissues to coun-

teract the constant inflowing of water from the exterior. Even before

the tissues have begun to take up water, it is probable that the kidneys,

stimulated by the modified diluted blood, react in such a way as to cause

an increased secretion of water. The urine formed under these condi-

tions has a lower specific gravity, lower osmotic pressure and lower

chlorine content than the normal urine. Moreover, the quantity of urine

secreted is in excess of the normal quantity. It is possible that the ex-

cessive secretion of urine is due in the last analysis to an increased

amount of water in the blood flowing through the capillaries of the kid-

ney. If any considerable quantity of water has entered, there must have

been a readjustment of the caliber of the blood vessels, since no marked

increase in blood pressure can be detected. Baglioni called attention to

the fact that when almost all the blood was withdrawn from an elasmo-

branch Scyllium, in a short time the blood contained almost the normal

percentage of urea, although it had a lower osmotic pressure than nor-

mally. Moreover, he found that a starving Scylliwm also exhibits a ten-

dency to retain its urea. It appears therefore that the cells of the kid-

ney are capable of retaining to a certain degree the urea as well as the

salts. It appears probable that the dog-fish possesses a mechanism for

the regulation of the osmotic pressure of its blood which is efficacious in

the case of slightly diluted external media.

T have shown, however, that at the time of death of Mustelus in fresh

water there is a deficiency of 15.5 per cent in urea and other nitrogenous

substances of the blood which I claim to be largely due to dilution of the

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 65

blood. ‘The chlorine of the blood has decreased nearly 26 per cent. This

probably means an excessive loss in salts, which would account for the

greater decrease in the osmotic pressure of the blood.

We may next consider the contribution of the salts and urea to the

osmotic pressure of the blood. The usual impression one gets from a

perusal of the literature is that the osmotic pressure of the blood is due

almost wholly to the presence of crystalloids, 7. e., chlorides and urea.

By the method of ashing, it is probable that some small part of the

chlorine is lost by volatilization. In the method used above for the de-

termination of the chlorine in serum, it is possible that a certain amount

of salts was retained by the diffusates. Nevertheless, every care was

taken to prevent error in the analyses. The determination of the urea

was likewise as carefully made. Dakin (’08) found that the blood of

Acanthias vulgaris, the freezing point of which is almost identical with

that of Mustelus, contained 0.88 per cent chlorine. The serum of Mus-

telus blood contains, according to my analyses, 0.86 per cent chlorine.

Expressed in terms of sodium chloride, this means that there was present

1.424 per cent NaCl. The urea formed 1.55 per cent of the blood (i. e.,

corpuscles and plasma). This is somewhat greater than the percentage

of salts. In the analyses given by other investigators, a greater amount

of urea than salts was also found. Moreover, when one takes into con-

sideration the differences in the osmotic pressure of the sea-water at the

stations where other investigations have been made, knowing selachian

blood to be approximately isotonic with its sea-water medium, one finds

that the change in the percentage composition of the salts and the urea

is proportional to the modification of the osmotic pressure of the external

medium.

By analysis, it was found that 1.55 per cent of the blood, plasma and

corpuscles is urea. This means that the urea constitutes 1.94 per cent

of the serum, which is equal to a 0.32 gram molecular solution. Since

the freezing point of a gram molecular solution is —1.84° (Nernst, 709)

a 0.32 solution would have a freezing point of about —0.59°. This

amount represents the lowering of the freezing point of the blood due to

urea. The salts present in the blood are, however, equivalent to a 0.24

gram molecular solution of sodium chloride. This, allowing for dissocia-

tion, has a freezing point of —0.85°*. This represents the lowering of

the freezing point due to the inorganic salts of the blood. The sum of

0.59° and 0.85°, or 1.44°, represents the lowering of the freezing point

of the blood due to both its urea and inorganic salts. The freezing point

of the blood is, however, —1.87°. There is thus left 0.43° to be ac-

3 As computed from Landolt and Bornstein’s Tabellen ’05.

66 ANNALS NEW YORK ACADEMY OF SCIENCES

counted for. Macallum (710) found that the urea and salts of the serum

of Acanthias vulgaris would not account for its freezing point. He con-

cluded that the difference between the freezing point of serum and that

produced by the combined salts and urea was due to the other organic

solutes. ‘These were found to be ammonia salts, which were present in

amounts sufficient to account for the additional depression of the freez-

ing point. We may infer that ammonia salts are present in the blood of

Mustelus. By these and other organic solutes, such as sugar, the freez-

ing point of the blood is brought to —1.87°. The réle of these sub-

stances, which are also crystalloids, has been too much neglected.

Mines (712) described the effects of electrolytes on the elasmobranch

heart. ‘The work was done at the laboratory of the Marine Biological

Laboratory at Plymouth, England. The normal freezing point of the

forms used was probably similar to that of Mustelus, namely, —1.87°.

Records were made showing the effects of solutions perfusing the heart.

The fluid was adapted from one used successfully by Knowlton, whose

results have not as yet been published. From the formula given by him,

I conclude that Mines’s solution must have had a freezing point less than

—1.52°. In other words, the solution was hypotonic to the blood which

normally bathed the heart. It contained about the same percentage com-

position of metallic elements (sodium, potassium, calcium and magne-

sium) as determined by Macallum, and urea and chlorides as determined

by myself. Since each of the kations has been shown by Mines to have a

specific effect on the heart action, his perfusion solution probably con-

tained the optimum amount of these substances. Baglioni’s experiments

on the maintenance of the heart beat of elasmobranchs were carried on

at Naples, where the mean freezing point of elasmobranch blood is

—2.29°. The author used two solutions, one being a 3.5 per cent solu-

tion of sodium chloride, which is isotonic with the blood. The other

solution consisted of 2 per cent sodium chloride + 2.2 per cent urea plus

a trace of calcium chloride. The computed freezing point of such a solu-

tion is about —2.00°. The freezing point of a solution of 2 per cent

urea + 2 per cent NaCl obtained by means of the Beckmann apparatus

is about 1.80°. Hence the solution with which Baglioni obtained his

results was in all probability somewhat hypotonic to the blood of the elas-

mobranchs he used.

If we subtract from the normal freezing point of the blood, the freez-

ing point due to the salts, 7. e., about —0.85°, there is a remainder of

—1.02° which is caused by urea and other substances in solution. It has

been noted that when the fish is immersed in fresh water, the nitrogenous

substances are decreased at death by 15.5 per cent. The freezing point

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 67

of the blood should undergo a similar reduction of 15.5 per cent of

—1.02°, or 0.158°. If the salts are diluted to the same extent as the

organic substances, there should be an additional rise in the freezing

point equal to 15.5 per cent of —0.85°, or —0.132°. This would make

the total change in the freezing point of the blood due to immersion in

fresh water equal to 0.29°, but, as a matter of fact, a rise of 0.408° was

noted on page 14. In other words, the change in the freezing point due

to dilution alone does not account for the maximum change observed by

actual experiment. How can the remainder of the change be accounted

for?

The total loss in chlorine and probably in salts from-the serum has

been shown to be 25.7 per cent. In the preceding paragraph, 15.5 per

cent of this loss has been ascribed to dilution. There remains 10.2 per

cent, or —0.087°, which I conclude represents the amount lost by diffu-

sion through the gill membranes. If 0.29° rise in the freezing point be

due to dilution, and a further rise of 0.087° be due to diffusion, the two

values combined account for a total rise of 0.377°. The observed rise

was 0.408°.

Dakin (708) in discussing work of a similar nature wrote, “Another

interesting point in the above results is that reduction in salt contents

of the blood as indicated by the chlorine contents is much greater than

the lowering of the osmotic pressure would lead one to expect.” This can

now be explained in the following manner: If the loss in salts had been

equal to the loss in organic substances then the percentage change in the

freezing point would have been equal to the percentage change in these

other substances. Since, however, the change in the salts is in excess of

the change in the other substances, it follows that the percentage change

in the freezing point of the blood is somewhat greater than the percentage

change due to organic solutes and somewhat less than the percentage

change in the salts. This is shown by the data. Thus there was a loss

of 15.5 per cent in organic solutes, a loss of 25.7 per cent in salts, but

only a loss of 21.9 per cent in the osmotic pressure of the blood. Hence,

not only do the calculations of the change in the freezing point of the

blood based on the results of chemical analysis confirm the general result

ascertained, by the direct determination of the freezing point, but it is

also possible to gain further insight into the nature of the changes pro-

duced.

It has been found that the blood is but slightly laked even at the time

of death in fresh water. At the same time, the ratio of the volume of

corpuscles to plasma increases. The corpuscles increase in volume. The

accompanying slight trace of laking shows that while the corpuscles as a

68 ANNALS NEW YORK ACADEMY OF SCIENCES

rule are swollen, a small number burst. In the swollen state it is possible

that their oxygenating function is interfered with. This would also

partially explain the effect on respiration.

At death in fresh water, the plasma is deficient in urea. Baglioni and

Mines have shown that urea is a necessary ingredient of the selachian

blood for the maintenance of normal cardiac activities. Baghoni con-

cluded that it promoted systolic tonus. He found that other substances,

such as cane sugar, cannot replace it, and that therefore urea is necessary

for its chemical effect on heart tissue rather than for its osmotic contri-

bution.

The deficiency of the blood in salts, however, is greater than in urea.

Baglioni concluded that the sodium salts increase diastolic tonus. He

found that an equal increase in urea and sodium chloride causes an in-

crease in systohe and diastolic tonus up to a certain point beyond which

cardiac activities come to a standstill. He concluded that in the propor-

tions in which the salts are found in the blood, systolic tonus counter-

acted diastolic tonus and the interaction of the two was necessary for

normal rhythmical contraction. It has been shown in the present paper

that the balance normally present between these two substances is upset,

for the blood is losing salts more rapidly than its urea. Loeb (711) has

called attention to the role of the salts of sodium, potassium, calcium and

magnesium in the preservation of life. He has maintained the impor-

tance of the proportion in which they exist in sea-water. The same pro-

portion of the same salts has been found by Macallum (710) in the blood

of animals representing different phyla. It has been shown in the pres-

ent paper that the salts diffuse out through the gill membranes, and it is

possible that the different ions pass out at different rates. Thus the

sodium and magnesium ions may pass out first of all because of their

speed of diffusion, and the potassium and calcium may pass out to a

smaller extent and later. Thus the normal relations of these ions so

necessary to the normal heart beat and to the activities of all tissues may

be thus changed. A more rapid loss of salts on the part of the blood than

on the part of the tissues leads to a disparity between the osmotic pres-

sures of the two. The tissues absorb water, as shown, leading to an

cedema. This interferes with their normal action—as, for example, the

water rigor of muscle.

The marine invertebrates, because of the lack of a quickly acting regu-

lative mechanism, are helpless in the event of a rapid change in the

molecular concentration of the external medium. Though their range

of movement is more restricted than that of the fishes, yet a regulative

mechanism must have been developed in the case of those forms which

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 69

have migrated into fresh water. Such a regulative mechanism is one of

the mechanisms of adaptation.

The dog-fishes, on the other hand, are migratory. I think it probable

that they are provided with a sensory apparatus by which they are made

aware of marked decreases in the concentration of the sea-water, with

the result that they avoid dilute media. The dog-fishes are provided in

addition with an excretory apparatus which is able to regulate to a modi-

fied extent the osmotic pressure of the blood. The result of this activity

of the kidneys is that the change in the osmotic pressure of the blood is

always less than the change in the external medium. The kidneys con-

serve those substances which contribute to the molecular concentration of

the blood and eliminate the excess of water. There is a limit, however,

to this life-saving action of the kidney.

The effect of a stimulus depends not only upon its intensity but also

upon the suddenness of it. Osmotic changes are induced more rapidly

by a sudden than by a gradual change from sea-water to fresh water. In

fact, in my experiments a sudden great change in the osmotic pressure

of the external medium sometimes caused a rupture of the gill membrane

at certain points with a resulting flow of blood. The gradual transition

from sea-water to fresh water prevented this bleeding from the gills.

Death occurs more quickly in such cases without a great change in the

osmotic pressure of the blood. These are simply instances of a wider

application of Du Bois Raymond’s law of stimulation. But it has been

shown (p. 28) that the osmotic change occurs through the gill mem-

branes. These, however, are not strongly resistant to changes in the

osmotic pressure of the external medium.

The reason that the dog-fish can withstand moderate changes in the

external medium is not because it resists these perfectly, but because the

organization of its protoplasm is of such a nature that life activities can

continue even though the osmotic character of its blood is considerably

modified. The heart of Mustelus continues to beat long after respira-

tion has ceased after immersion in fresh water. Squalus and other elas-

mobranchs live in the dilute sea-water at the New York Aquarium; and

yet the osmotic pressure of the blood of Squalus, while considerably above

that of the harbor water, is still but nine-tenths of that found in fishes

living in sea-water. The osmotic pressure of the blood of higher forms

never has been proportionately reduced without serious impairment if

not cessation of protoplasmic activities.

Moore (708), in advancing strong arguments to show the failure of the

membrane theory to account for the equilibrium between the cell and its

environment, suggested that the cell was able to undergo reversible proc-

"0 ANNALS NEW YORK ACADEMY OF SCIENCES

esses of association and dissociation with the constituents outside of it.

Such association is in the nature of more or less stable chemical combi-

nations which he terms adsorpates. For each cell there is a range of

osmotic pressure within which partial association and discussion is pos-

sible, and within this range labile exchanges are possible.

This idea may be extended to explain why the tissues of the dog-fish,

though normally adapted to an osmotic pressure of its blood approxi-

mately equal to that of the sea-water, is able to live in the dilute sea-

water of New York harbor. In such dilute water, the blood has an os-

motic pressure represented by a freezing point of —1.70°. This repre-

sents the lowest osmotic limit of the blood at which the cells of the dog-

fish can establish proper associations with the substances in the blood, or

in other words at which the metabolic processes can take place. It is of

interest to note that this freezing point, namely, —1.70°, is also the least

noted in the case of the smooth dog-fish, Mustelus, at Woods Hole (see p.

7). Continuing Moore’s conception, it is probable that —1.87° repre-

sents the optimum osmotic pressure at which the labile processes of asso-

ciation and dissociation can most perfectly take place. Greene (’05) im-

plies the same idea, for he concludes that salmon having blood with an

osmotic pressure widely different from the mean are in a pathological

condition. Dakin (708), Dekhuyzen (’04) and others who have deter-

mined the freezing points of teleost blood seem impelled to insist on its

constancy ; yet considerable variation appears in the actual results noted

by them. Variations occur even in human blood at different times of

day, as shown on page 6. Winter (796) has maintained that metabolic

processes would cease if the osmotic pressure of the blood should attain a

stagnant dead level.

It should be observed in this connection that the freezing point of the

blood of the dog-fish at the New York Aquarium remains at about.

—1.70°, while the water in which they live has a freezing point of about

—1.00°. The animal is able to prevent a further lowering in the osmotic

pressure of the blood. It cannot resist perfectly the change in the os-

motie pressure of the external medium, but it is able to carry on life

processes at the lower limit. It is possible to conceive that because of the

dilute condition of the blood, the cell finds great difficulty in establishing

normally stable associations. Life processes are continued, but with de-

creased efficiency. Indeed observation shows that the elasmobranchs at

the New York Aquarium are less vigorous and hardy than those at Woods

Hole.

The blood of the fishes living at the lower limit, namely, having a

freezing point of —1.70°, is not as dilute as the blood of Mustelus at the

SCOTT, STUDY OF CHANGES IN MUST'ELUS CANIS "1

time of death in fresh water. In fact, the change in the osmotic pressure

of the blood due to dilution alone would cause a rise in the freezing point

of the blood of about 0.30°. Therefore, mere dilution of the blood up to

the point at which salts begin to diffuse out would pass the limit in the

range in the osmotic pressures of the blood and cause death. This ex-

plains why the dog-fish failed to regain the normal freezing point of its

blood on return to sea-water after a change of about 0.30° due to immer-

sion in fresh water. Because of such a reduction in the osmotic pressure

of the blood the constitution of the protoplasmic molecules is disturbed

in part, and on the return to sea-water the normal relations fail to be

regained.

CONCLUSIONS

The following conclusions regarding the osmotic relations of Mustelus

canis seem to be warranted:

The osmotic pressure of the blood of the fish varies about an optimum

represented by a freezing point of —1.87°.

The change in the osmotic pressure of the blood due to changes in the

molecular concentration of the external medium depends,

ist, upon the time of immersion in the external medium, and,

2nd, upon the modification in the molecular concentration of the ex-

ternal medium.

The change in the osmotic pressure of the blood is not equal, but yet

bears quite a constant ratio to the change in the molecular concentration

of the external medium. The blood of Squalus living in brackish water

has a higher osmotic pressure than that of the water in which it lives.

When a considerable modification in the osmotic pressure of the blood

is brought about by immersion of the fish in solutions hypotonic or hy-

pertonic to sea-water, the normal osmotic pressure of the blood is not

regained by the return of the fish to sea-water.

The changes in the osmotic pressure of the blood take place through

the gill membranes.

The osmotic pressure of the blood is not greatly modified by the ab-

straction of one-half the total quantity of blood in the body.

Although the blood is but faintly laked on immersion of the fish in

fresh water, the corpuscles are swollen.

The resistance of the erythrocytes of elasmobranchs to hemolysis is

not much inferior to that of the marine teleosts and appears to be inde-

pendent of osmotic relations of the corpuscles to its surrounding medium,

nor does there appear to be any close relation between the resistance of

the corpuscles to hemolysis and the salt content of the plasma.

ANNALS NEW YORK ACADEMY OF SCIENCES

When Mustelus is immersed in hypertonic solutions of sea-water, not

only does the osmotic pressure of the blood increase but also its chlorine

content.

The specific gravity of the blood decreases on immersion of the fish in

fresh water.

When the fish is immersed in fresh water, a certain amount of decrease

in the osmotic pressure of the blood can be ascribed to dilution of the

blood caused by the absorption of water through the gill membranes. In

addition, a further change is due to diffusion of salts outward through

the gill membranes, as is shown by the presence of considerable quantities

of chlorine in the water in which the fish is immersed.

The tissues of the body tend to maintain the osmotic pressure of the

blood by absorbing water from the hypotonic blood and this tends to raise

the pressure.

By secreting rapidly a diluted urine, the kidneys also tend to maintain

the normal osmotic pressure of the blood. By this process, the urea and

a certain amount of the salts of the blood are conserved.

The changes in blood pressure due to immersion in fresh water are

slight as compared with the effects upon respiratory and cardiac activity.

On immersion in fresh water, there is a gradual failure of respiration :

this is marked by irregularly repeated spasmodic respiratory movements

which increase in intensity for a period and then decline.

When the sea-water in which the fish is immersed is gradually changed

to fresh water, the heart beat increases in amplitude and decreases in

rate. The contractions gradually diminish in force, although the heart

continues to beat faintly after respiration has ceased.

Coincident with and similar in character to the spasmodic movements

of respiration, spasmodic contractions of the heart occur.

The normal osmotic pressure of the blood of Mustelus is maintained

only by the organism remaining in sea-water. It is probably provided

with a sensory apparatus by which it is able to avoid great modifications

of the external medium. In slightly brackish waters, the osmotic pres-

sure of the blood is diminished by the influx of water through the gill

membranes; but because of the regulative activity of the kidneys and

other bodily tissues, the changes are less than the changes in the external

medium, and are still within the range of pressures compatible with life.

With greater changes in the molecular concentration of the external

medium the organism succumbs.

The gill membranes are probably not greatly injured by this absorption

of water, for the animal continues to live indefinitely, as is shown by the

elasmobranchs in the New York Aquarium. It may be concluded that

SCOTT, STUDY OF CHANGES IN MUSTELUS CANIS 93

the death of Mustelus is due to the following effects produced by immer-

sion in fresh water: increased permeability of gill membranes; dilution

of the blood; swelling of corpuscles; partial hemolysis; excessive loss of

salts from the blood; a fall of nearly one-fourth in the osmotic pressure

of the blood ; an associated cedema of the tissues, and a failure of respira-

tory and cardiac activities.

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irregular intervals. It is intended that each volume shall be devoted to

monographs-relating to some particular department of Science. Volume

I is devoted to Astronomical Memoirs, Volume II to Zodlogical Memoirs,

etc. The price is one dollar per part as issued.

_ All publications are sent free to Fellows and Active Members. The

Annals are sent to Honorary and Corresponding Members desiring them.

Subscriptions and inquiries concerning current and back numbers of -

any of the publications of the Academy should be addressed ‘to

THE LIBRARIAN,

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eare of

American Museum of Natural History,

New York, N. Y.

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_ ANNALS OF THE NEW YORK ACADEMY OF SCIENCES

eo _ Vol. XXIII, pp. 77-83

Editor, Epmunp Ot1s Hovey

E CORRECTIONS AND ADDITIONS TO “LIST

OF TYPE SPECIES OF THE GENERA AND.

_ SUBGENERA ‘OF FORMICIDE” =~

Wittram Morton’ WHEELER _

ss | ie EW “BORK:

~~ >>. PUBLISHED. BY THE ACADEMY

ES ae 29 May, 1913 :

THE NEW YORK ACADEMY OF SCIENCES

(Lyceum or Narurau History, 1817-1876)

OFFICERS, 1913

President—EMeErson McMituin, 40 Wall Street

Vice-Presidents—J. EpMunp Woopmayn, W. D. MarrHew

CHarLes Lane Poor, WenpDELL T. Bus

Corresponding Secretary—HeEnry E. Crampron, American Museum

Recording Secretary—Epmunp Oris. Hovey, American Museum

T'reasurer—HENryY L. DoHerty, 60 Wall Street

Librarian—Ratpu W. Tower, American Museum

Editor—EpMunp Otis Hovey, American Museum

SECTION OF GEOLOGY AND MINERALOGY

‘ Chairman—J. BE. Woopman, N. Y. University

Secretary—Cuar.es T. Kirx, Normal College

SECTION OF BIOLOGY

Chairman—W. D. Marruew, American Museum | P

Secretary—Wi.u1amM K. Grecory, American Museum 3

SECTION OF ASTRONOMY, PHYSICS AND CHEMISTRY :

Chairman—CHARLES Lane Poor, Columbia University ; 4

Secretary—F. M. PEDERSEN, College of the City of New York

SHCTION OF ANTHROPOLOGY AND PSYCHOLOGY a

Chairman—Wenvett T. Busu, 1 West 64th Street ey

Secretary—Roxsert H. Lowiz, American Museum | Ee

| The sessions of the Academy are held on Monday evenings at 8:15

o'clock from October. to May, inclusive, at the American Museum of .

Natural History, 77th Street and Central Park, West. 7

[ANNALS N. Y. Acap. Scr., Vol. XXIII, pp. 77-83. 29 May, 1913]

CORRECTIONS AND ADDITIONS TO “LIST OF TYPE

SPECIES OF THE GENERA AND SUBGENERA

OF FORMICIDA”

By WILLIAM MortToN WHEELER

Since my list of generic and subgeneric types of the Formicide was

published,t Mr. Sievert Rohwer has kindly called my attention to some

type determinations of earlier dates than those I recorded and especially

to the genus Cephalotes Latreille, which has been incorrectly cited by

Dalla Torre in his “Catalogus Hymenopterorum” and generally ignored

by myrmecologists. Prof. Carlo Emery has called attention to a few omis-

sions and incorrect determinations of types,? and I have myself detected

several others. While seizing the opportunity to make corrections, I have

added the types of a number of new genera and subgenera established

during or since the publication of my paper. In this list of additions

there are a number of subgenera of Camponotus recently published by

Forel. Strangely enough, he does not designate the types, although noth-

ing could have been more necessary in splitting up such a huge and per-

plexing genus as Camponotus. When he mentions several species belong-

ing to one of these new subgenera, I have uniformly selected the first: as

the type, not because I am an unqualified adherent to the “first species

rule,” but because Forel probably intended to indicate the first species as

the type.

CORRECTIONS

Aneleus Emery.—I cited Solenopsis similis Mayr as the type of this

subgenus, supposing it to be monobasic, but this is far from being the

case. Emery cites six species of Pheidologeton as belonging to Aneleus,

and as he mentions Ph. pygmeus Emery as the first in his list, this should

be regarded as the type, especially as the soldier or most characteristic

phase of the oldest known species, S. similis, has not been described.

Atopogyne Foret.—Emery prefers to regard Formica depressa Ja-

treille as the type of this subgenus, instead of Crematogaster hellenica

Forel, the species I selected, because depressa is the most characteristic

1 Annals N. Y. Acad. Sci., Vol. XXI, pp. 157-175. 1911.

2Les Espéces-Type des Genres et Sous-Genres de la Famille des Formicides. Ann.

Soc. Ent. Belg., LVI, pp. 231-233. 1912.

(77)

78 ANNALS NEW YORK ACADEMY OF SCIENCES

species and because it was Forel’s intention to regard it as the type, as he

subsequently stated in a letter to Emery.

Azteca Forrt.—The type of this genus is not Tapinoma instabilis

F. Smith, but Azteca instabilis Forel (=A. muellert Emery), as Emery

maintains (Genera Insect. Fasc. 137, p. 31, 1912).

Cataglyphis Férster.—This should rank as an independent genus

and not as a subgenus of Myrmecocystus.

Cephalotes Larreitte.—The type is incorrectly cited as Formica

cephalotes LL. (==Atta cephalotes) instead of F. atrata L. (= Crypto-

cerus atratus). The genus Cephalotes was unfortunately regarded by

Dalla Torre as a synonym of Atta Fabr., but it is evidently synonymous

with and must replace Cryptocerus, as Mr. Rohwer maintains (im lit-

teris). Latreille described Cephalotes in the third volume of his Hist.

Nat. Crust. Insect., p. 357, which was published in 1802. The only spe-

cies cited as an example is Formica atrata. On this same species he also

based his genus Cryptocerus in the thirteenth volume of the same work,

published in 1804 according to Mr. Rohwer, or 1805 according to Hagen

(Biblioth. Ent., p. 453) and Dalla Torre. It is evident, therefore, that

Cryptocerus is isogenotypic with the earlier Cephalotes and must be con-

signed to the synonymy.

Condylodon Lunp.—The word “monobasic” should be added.

Cosmacetes SprnoLta.—The word “monobasic” should be added.

Crematogaster Lunp.—Prof. Emery insists that the name of this

genus should not be written Cremastogaster, because Lund, who mentions

it only once, gives the word with a single s, and it is not certain that we

are dealing with a typographical error. Emery also implies that Bing-

ham was wrong in designating Formica scutellaris Olivier as the generic

type. Lund cites no species in connection with Crematogaster, which is

saved from being a nomen nudum only by the clear description of the

abdomen, which exhibits peculiarities not found in any other genus of

ants. As he had in mind only Brazilian species, Emery believes that one

of these, e. g., Formica acuta Fabr., should be selected as the type. It

might be contended, on the other hand, that in such a widely distributed

and homogeneous genus as Crematogaster, it is better to select the com-

mon European form C. scutellaris, which is, moreover, closely related to

the typical North American C. lineolata Say. At any rate, it is too late

to make a change, because Bingham’s designation, unless an earlier is

found, will have to stand.

Eciton LATrErLLE.—Shuckard (Swainson and Shuckard, Hist. & Nat.

Arrang. Ins., p. 173. 1840) states that Formica hamata Fabr. is the

type of this genus.

WHEELER, ADDITIONS TO FORMICIDA 79

Formica L.—Formica rufa L. is given as the type of this genus by

Girard (Traité Elém. d’Ent., II, p. 1011. 1879).

Gnamptogenys Rocrer.—My designation of Hctatomma concinnum F.

Smith (nec Mayr) as the type of this subgenus is erroneous. Hmery has

rightly selected G. tornata, the first of two species described by Roger.

Holcoponera Mayr.—Now ranks as an independent genus.

Labidus Jurine.—According to Mr. Rhower, Latreille designated L.

latreillei Jurine (= EHciton (Labidus) cecum Latr.) as the type of this

subgenus as early as 1810.

Leptothorax Mayr.—Emery selects L. clypeatus Mayr as the type of

this genus, both because it was the first species described by Mayr and

because L. acervorum Nylander has already been made the type of the

subgenus Mychothorax by Ruzsky.

Myrmecia Fasricius.—Shuckard (Hist. & Nat. Arrang. Ins., p. 173.

1840) designated Formica gulosa Fabr. as the type of this genus.

Myrmica LarTreILye.—Girard designated Formica rubra L. as the

type of this genus (Traité Elém. d’Ent., II, p. 1016. 1879).

Oecodoma LatrEeILLe.—Formica cephalotes L. is designated as the:

type of this genus by Shuckard (Hist. & Nat. Arrang. Ins., p. 174.

1840).

Rhytidoponera Mayr.—This now ranks as an independent genus. I

selected Hctatomma metallicum. F. Smith as its type. Emery designates:

| £. araneoides Le Guillou (—rugosum F. Smith) (Gen. Insect., Fase.

118. 1911), because it is the first species cited by Mayr and because he,,

Emery, had previously (1879) based the subgenus Chalcoponera on E..

metallicum. I do not regard the first reason as cogent; the second is, of:

course, valid and sufficient.

Tetramorium Mayr.—formica cespitum L. is designated as the type

of this genus by Girard (Traité Elém. d’Ent., II, p. 1016. 1879).

Trigonogaster ForeLt.—Through a blunder of my amanuensis or of

the printer the type of Triglyphothriz is repeated under this head. The

correct type is Trigondgaster recurvispinosa Forel.

ADDITIONS

Allopheidole Foret. Mém. Soc. Ent. Belg., XIX, p. 237. 1912. (Sub-

genus of Pheidole.)

Type: Pheidole kingi Ern. André (by present designation).

Atopodon Fore... Rey. Suisse Zool., XX, p. 771. 1912. (Subgenus of

Acropyga.)

Type: Acropyga (Atopodon) ineze Forel. (First of three species by

present designation. )

80 ANNALS NEW YORK ACADEMY OF SCIENCES

Atopula Emery. Ann. Soc. Ent. Belg., LVI, p. 104. 1912. (Subgenus

of Vollenhovia. )

Type: Atopomyrmex nodifera Emery (designated by Emery).

Chalcoponera Emery. Ann. Mus. Stor. Nat. Genova, XXXVIII, p.

547. 1897. (Subgenus of Rhytidoponera.)

Type: Ectatomma metalliicum F. Smith (designated by Emery).

Decapheidole Forrt. Mém. Soc. Ent. Belg., XIX, p. 237. 1912.

(Subgenus of Pheidole.)

Type: Pheidole perpusilla Emery (by present designation).

Emeryopone Foret. Rev. Suisse Zool., XX, p. 761. 1912.

Type: Emeryopone buttel-reepent Forel (monobasic).

Forelomyrmex nom. nov. for Janetia Foren (1899), which is preoccu-

pied by Janetia Kieffer (1896), a genus of Itoniidee (Cecidomynde@).

Holcoponera Cameron. Whymper’s Travels in the Andes, Suppl., p.

92. 1891. (=—Cylindromyrmer Mayr.)

Type: Holcoponera whympert Cameron = Cylindromyrmex striatus

Mayr (monobasic).

Hylomyrma Foret. Mém. Soc. Ent. Belg., XX, p. 16. 1912. (Sub-

genus of Pogonomyrmez.)

Type: Pogonomyrmex (Hylomyrma) columbicus Forel (designated

by Forel).

Isopheidole Forret. Rev. Suisse Zool., XX, p. 765. 1912. (Subgenus

of Pheidole.)

Type: Aphenogaster longipes F. Smith var. longicollis Emery (mono-

basic).

Leptomyrmula Emery. Genera Insect., Fase. 137, p. 16, nota. 1912.

Type: Leptomyrmex maravigne Emery (monobasic).

Machaerogenys Emery. Gen. Insect., Fasc. 118, p. 100. 1911. (Sub-

genus of Leptogenys.) |

Type: Leptogenys truncatirostris Forel (designated by Emery).

Mesomyrma Srirz. Stitzb. Gesell. naturf. Freunde Berlin, p. 363.

1911. (Subgenus of Podomyrma.)

Type: Podomyrma (Mesomyrma) cataulacoidea Stitz (monobasic).

Metapone Foret. Rev. Suisse Zool., XIX, p. 447. 1911.

Type: Metapone greeni Forel (monobasic).

Myrmamblys Foren. Mém. Soc. Ent. Belg., XX, p. 90. 1912. (Sub-

genus of Camponotus.)

Type: Camponotus reticulatus Roger (by present designation).

Myrmentoma Foret. Mém. Soc. Ent. Belg., XX, p. 92. 1912. (Sub-

genus of Camponotus. )

Type: Formica lateralis Olivier (by present designation).

WHEELER, ADDITIONS TO FORMICIDA 81

Myrmepomis Foret. Mém. Soc. Ent. Belg., XX, p. 92. 1912. (Sub-

genus of Camponotus.)

Type: Formica sericeiventris Guérin (by present designation).

Myrmeurynota Foret. Mém. Soc. Ent. Belg., XX, p. 92. 1912. (Sub-

genus of Camponotus. )

Type: Camponotus eurynotus Forel (by present designation).

Myrmobrachys Foret. Mém. Soc. Ent. Belg., XX, p. 91. 1912. (Sub-

genus of Camponotus. )

Type: Formica senex F. Smith (by present designation).

Myrmogigas Foret. Mém. Soc. Ent. Belg., XX, p. 91. 1912. (=

Dinomyrmex Ashmead; subgenus of Camponotus.)

Type: Formica gigas Latreille (by present designation).

Myrmogonia Foret. Mém. Soc. Ent. Belg., XX, p. 92. 1912. (Sub-

. genus of Camponotus.)

Type: Camponotus laminatus Mayr (by present designation).

Myrmophyma Foret. Mém. Soc. Ent. Belg., XX, p. 91, 1912. (Sub-

genus of Camponotus.)

Type: Camponotus capito Mayr (by present designation).

Myrmorhachis Forre,. Mém. Soc. Ent. Belg., XX, p. 92. 1912. (Sub-

genus of Camponotus. )

Type: Camponotus polyrhachoides Forel (by present designation).

Myrmosaga Foret. Mém. Soc. Ent. Belg., XX, p. 92. 1912. (Sub-

genus of Camponotus. )

Type: Camponotus kelleri Forel (by present designation).

Myrmosericus Forex. Mém. Soc. Ent. Belg., XX, p. 91. 1912. (Sub-

genus of Camponotus.)

Type: Formica rufoglauca Jerdon (by present designation).

Myrmosphincta Foret. Mém. Soc. Ent. Belg., XX, p. 92. 1912. (Sub-

genus of Camponotus.)

Type: Formica sexguttata Fabricius (by present designation).

Myrmotarsus Foret. Mém. Soc. Ent. Belg., XX, p. 92. 1912. (Sub-

genus of Camponotus. )

Type: Formica mistura F. Smith (by present designation).

Myrmothrix Foren. Mém. Soc. Ent. Belg., XX, p. 91. 1912. (Sub-

genus of Camponotus.)

Type: Formica abdominalis Fabricius (by present designation).

Myrmotrema Foret. Mém. Soc. Ent. Belg., XX, p. 91. 1912. (Sub-

genus of Camponotus.)

Type: Camponotus foraminosus Forel (by present designation).

82 ANNALS NEW YORK ACADEMY OF SCIENCES

Myrmoturba Foret. Mém. Soc. Ent. Belg., XX, p. 91. 1912.

genus of Camponotus. )

Type: Formica maculata Fabricius (by present designation).

Neoformica subgen. nov. (Subgenus of Formica.)

Type: Formica pallidefulva Latreille (by present designation).

Octostruma ForEL. Meém. Soc. Ent. Belg., XIX, p. 196. 1912.

genus of Rhopalothriz.)

Type: Rhopalothrix simoni Emery (by present designation).

Odontopelta Emery. Genera Insect., Fasc. 118, p. 101. 1911.

genus of Leptogenys.)

Type: Leptogenys (Lobopelta) turnert Forel (monobasic).

Pachysima Emery. Ann. Soc. Ent. Belg., LVI, p. 97%. 1912.

genus of Sima.)

Type: Sima ethiops F. Smith (designated by Emery).

Parectatomma Emery. Genera Insect., Fasc. 118, p. 44. 1911.

genus of Hctatomma.)

Type: Hctatomma triangulare Mayr (designated by Emery).

Pentastruma Foret. Entom. Mittheil., I, p. 51. 1912.

Type: Pentastruma sautert Forel (monobasic).

Phasmomyrmex Srtirz. Mitth. Zool. Mus. Berlin, V, p. 146.

(Subgenus of Camponotus. )

Type: Camponotus buchnert Forel (monobasic).

Physocrema Foret. Mém. Soc. Ent. Belg., XIX, p. 220. 1912.

genus of Crematogaster.)

(Sub-

L9L0:

(Sub-

Type: Crematogaster inflata F. Smith (by present designation).

Poneracantha Emery. Ann. Mus. Stor. Nat. Genova, XX XVIII, p.

548. 1897. (Subgenus of Hctatomma.)

Type: Hctatomma (Poneracantha) bispinosum Emery (monobasic).

Pristomyrmecia Emery. Genera Insect., Fasc. 118, p. 21. 1911.

genus of Myrmecia.)

(Sub-

Type: Myrmecia mandibularis F. Smith (designated by Emery).

Proatta Foret. Rev. Suisse Zool., XX, p. 768. 1912.

Type: Proatta butteli Forel (monobasic).

Promyrma Foret. Rev. Suisse Zool., XX, p. 764. 1912.

Type: Promyrma buttelt Forel (monobasic).

Promyrmecia Emery. Genera Insect., Fasc. 118, p. 19. 1911.

genus of Myrmecia.)

Type: Myrmecia aberrans Forel (designated by Emery).

Psammomyrma ForeL. Mém. Soc. Ent. Belg., XIX, p. 237.

(Subgenus of Dorymyrmez.)

Type: Dorymyrmex planidens Mayr (by present designation).

(Sub-

1912.

WHEELER, ADDITIONS TO FORMICIDA 83

Stegomyrmex Emery. Ann. Soc. Ent. Belg., LVI, p. 99. 1912.

Type: Stegomyrmex connectens Emery (monobasic).

Terataner Emery. Ann. Soc. Ent. Belg., LVI, p.103. 1912.

Type: Atopomyrmesx foreli Emery (designated by Emery).

Tetramyrma ForEL. Rev. Suisse Zool., XX, p. 766. 1912. (Sub-

genus of Dilobocondyla. )

Type: Dilobocondyla (Tetramyrma) braunsi Forel (monobasic).

Trachymesopus Emery. Genera Insect., Fasc. 118, p. 84. 1911. (Sub-

genus of Huponera.)

Type: Formica stigma Fabricius (designated by Emery.)

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—

ANNALS OF THE NEW YORK ACADEMY OF SCIENCES

Vol. XXIII, pp. 85-143; pll. EVI

Kditor, Epmunp Otis Hovey

A CONTRIBUTION TO THE GEOLOGY OF

____ THE WASATCH MOUNTAINS, UTAH

Ferpinanp Frus Hinrze, JR.

: NEW YORK

PUBLISHED BY THE ACADEMY

12 Decemser, 1913

THE NEW YORK ACADEMY OF SCIENCES

(Lycrum or NaturaL History, 1817-1876)

OFFIcERS, 1913 _

President—Emerrson McMiu.in, 40 Wall Street ~

Vice-Presidents—J. EpMUND Woopman, W. D. MartHEw

CHARLES LANE Poor, WENDELL T. BusH

Corresponding Secretary—HxEnry E. Crampron, American Museum

Recording Secretary—Epmunp Otis Hovey, American Museum

Treasurer—Heinry L. Donerty, 60 Wall Street

Librarian—Ratpu W. Tower, American Museum

Editor—Epmunp Otis Hovey, American Museum

SECTION OF GEOLOGY AND MINERALOGY

- Chairman—J. E. Yoopman, N. Y. University

Secretary—A. B. Pactint, 147 Varick Street

SECTION OF BIOLOGY

Chairman—W. D. MattHErw, American Museum

Secretary—WiLL1AM K. Gregory, American Museum

SECTION OF ASTRONOMY, PHYSICS AND CHEMISTRY

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SECTION OF ANTHROPOLOGY AND PSYCHOLOGY

Chairman—WeENDELL T. BusH, 1 West 64th Street

Secretary—Rosert H. Lowiz, American Museum

‘The sessions of the Academy are held on Monday evenings at 8:15

o’clock from October to May, inclusive, at the American Museum of —

Natural History, 77th Street and Central Park, West.

[ANNALS N. Y. Acap. Sctr., Vol.. XXIII, pp. 85-143, pll. I-VI. 12 December,

1913]

A CONTRIBUTION TO THE GEOLOGY OF THE WASATCH

MOUNTAINS, UTAH?

By FererDInanp Friis HIntTzx, JR.

(Read by tatle before the Academy, 5 May, 1918)

CONTENTS

Page

PRISED TIM centre tk gL hae AO eg aba Bib hee he AG Wien. ws MR Cw 86

TERMS yr aN ae a, itn edo at estas ai Nea lela De ccwl'y Seated whaneudke aie ale we i.

MMEIMeR CMU OSA, MIOUMEAITIS. yc... cece 3 ole aiden Wclewewen weseeucde 87

Serene eevee MAT Gly UIUC ohh Sic. aia) aie, ich s.c.c lace Kebey o's wae Gas e siead slea'ea cme 88

meee aU Pe tN Re ai inl ie hares 8 bo Gis 06 aU icee vee see 6 e's WALA Mee oe eet 91

ENN RINNE Sor MCR dy este ect svete Siac aiaieidve.e Ce weirs iniele’e'ale je aside me aude 92

Sin ene COMP iP OVO NIG) 6c. wh cin xt ob: bs 're ids isc chkla GG n Sle e'e a lehe suela amleiewe aiacs 92

ear RENE N CLTEIUT Sits Sic Give ole dso six oa wlale s vie b duel eerie pave pieeisdlb.e a 93

Daa MmrAma IB ee EST TENG sche chap cP. =) 2) «aac So) 5 ae 4). elene'm v obs Sine hboe we Gasmeieete 94

Re eee OUP ESE CHION 1) ao bids) - sic v aveisg Woe ake se cceeceleiaadeeeew eee 95

ee MES ALES Reranch Tenia Vat Seve Par iaics Ge) ea. dies) o.ws0 es ,e.a oe ete ew Sw Rieleiw dees 95

eer eI TOA PCHEAIN.:...../60e.. wares oda ee eens ee wiieeeae 99

Origin and nature of the Algonkian sediments................05. 102

eI Raa Ronee RS fot vcd dicicee cic fet ora ic: alle iol wield fd Aw Gileper eo lao wie apd aie Bbw nd We 103

SM SOMME Te PNS eee tA aye in eka b Sy ahah oh id ein aye ce «abe. 'e wiv ele le wi¥'s © eles a ele ® 105

ERO col Pe CON Or gl GRU Re Soe a 105

rm PIE ENE Ne chong JW Set ocd as Cees) Sa eel Geshe les Ge sie a. POSSE PYAR A Sie ny 107

Rene Er Ss IE SUN eek PrN en nreeial ost Tel acs. a ur i dia a0 « (o,(\'6i 00 Giace! a average sikle a'% oca oie 108

SCREEN Pn anI SO NCL REEVENE fh g es ee vc faceh da cvs? si 0) u/cah wird loy'e."atelavm, ale! bee le @ierehalets a'at 109

Seeing Geen AAV GM, «52. sco als do é'ab-s. de Sha Pauwlds TPT oe He eR af 110

Ouray type of Devonian in the Central Wasatch................. 1

CI OME PEEVE LAA UE TIE AD re hs ek hacia ae lwo es oe Riera olin, IG did 0 bree eld ave, a8. wale 113

Unconformity between the Mississippian and Pennsylvanian...... 115

PEC GEC GION. o\sia-t ainte lara ate wie! ooea ea? 6's BSAA Oe ae CL Pe oe ery

Pennsylvanian strata........... Rem MSTA Ete he imine lye hie Sra ping 120

eM EMI SCONE e Sots net, Gr cka ick iki ds Sidi bie pelpia Wie aineos aie ose cies a 120

Park City and sb go TESOL DS TOV Sie Cueto RU Ne and a eT 123

Seen SMM UD PETTITT PA DIO oa) iis cle lele sd ciel ccc ee des caw apcegsneretenus 126

PC ME hg odbc a dls vais oa vcd dale LER a hye chasers yay et A Se ties eee ae 127

Introductory rear en INI REPROD Re ie eters e Naru" Ge blela mele o: 8 7a éte a: eae! d ado ahw ese ete 127

ree PCE MCOTETAL VWWABELCH 0a cinis peisla wen swage cue escsviiaceducic 127

Peni MIT SERENA, cs ond a'sia se viels Sas sek aege aes ce samt aeke 128

nee RTE TP aha oe als vies dade eid eS caacn ce Ua knmeeepetades 130

Sma MneeT eer CRITTER oy Ge! ila ate y's,» 0\pe\ os «:'e (Wla'w Ae-a tums dws ees edie eles 133

Sine TR EOA Eee NOTED IE Toe crate fsa. n Wve Seve sa cise © <, wlald.b-die ale ore ¥e'wa we swe 136

Sen NEE sa, bers e Wat aie Ut twit ie hie tw ce cdcale's dre! tele Ow aierGei a) bweee aus ata 137

Oo Peer Ser Me ira lk silts 2 Nig wh Wibialeteidia Wiel’ wale wil slasiticwle come ae 138

1 Manuscript received by the Editor, 26 April, 1913. (85)

86 ANNALS NEW YORK ACADEMY OF SCIENCES

Page

Silver Work ‘fault: 006 vse cre ao ee ae ee ee 139

Minor faults ..ai. 2 ose eds 6 ao Saheede POO OC Cee eee 139

SUMIMATY. OF ‘CONCHISIONS ? 56... 2 Gaus es se ew wie eater oe ee eee 140

PHYSIOSTAPHY: «sc scus0-5 0-dhe Sw eros eames aw RRO ees, CELE eee 140

Straticraph yy. hss. 4.0% o's 6 ications eelece ys AU etOe te Ioae © ho aE enn ee 141

SEPUCHURE soso caa eles ow Gis ole Wie, clei lore erebouse ercberereten lece ehexolebetetete Pes. Marat oe ee 141

BIDMOSTAP AY sibs, 5. isis tie, 5 wis ns hs ome selves ca) le Lakers Paves Tenerelgol her ictekts eal erat see rekon ee 142

PRY SIOSTAPIY =o eis i dic ea SAGs Sawse ie ole eheete ak eset Saal RCE te ene ee eee 142

Stratigraphy and paleontology.....c. fhjciel. «cieteisieie faye eicne eons Ae en 142

Struchure: 452 6 ibe ask Boks et oie ein Renee eee SRS Bien ac 143

INTRODUCTION

The general geological features of the Wasatch Mountains have long

been known from the comprehensive reports of the early federal surveys.

Since these general studies were made, several special problems have

been investigated, with the result that many new facts have been added,

in the light of which, many of the first conceptions have been greatly

modified.

One of the most important of these later observations is concerned

with the structure. The complicated tectonic features of this remarkable

range are only now beginning to be appreciated. The finding of large

overthrusts in the vicinity of Ogden by Blackwelder in 1909 and the

‘tracing of the great Bannock thrust from southern Idaho south into the

Wasatch range accomplished by Richards and Mansfield of the U. S.

Geological Survey within the last year or two have added much impor-

tance to this phase of the structure. Boutwell had previously discovered

overthrusts in the Park City district, but they were thought to be local

features and were not greatly emphasized.

As might be expected, the unravelling of the structure has had an im-

portant bearing upon the stratigraphy of the range, especially since the

regions in which the overthrusts have been found were those that fur-

nished the type sections to the early workers. The repetition of beds

brought about by overthrusting escaped the attention of the Fortieth

Parallel geologists, who gave the first unified account of the stratigraphy,

and their section is therefore subject to correction.

It is the purpose of the writer to present in this paper a number of

facts that were observed in the summer of 1912 in the central part of

the Wasatch range, particularly in Big and Little Cottonwood Canyons,

and to discuss the structure and stratigraphy of that region. The dis-

covery of a great overthrust at Alta, in Little Cottonwood Canyon, has

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 87

led to a new conception of the stratigraphy as well as the structure of

this part of the range. The finding of many new fossil species has shed

important light on the age of the paleozoic rocks, and the discovery of

several disconformities has enabled the writer to subdivide the series into

several new formations. Observations on the physiographic features of

the central Wasatch have afforded interesting results on the present state

of dissection of the Wasatch block mountain and have suggested an ex-

planation of the principal drainage lines of the region. Other problems

are partly solved, and much work will still have to be done before a com-

plete account of the many interesting geological phenomena here shown

can be given.

The writer desires to thank the mining men of South Fork and Alta

most heartily for the support and assistance which they generously ex-

tended to him during his field work. While it does not seem possible to

mention the names of all who have rendered help, the writer cannot for-

bear to acknowledge the cordial treatment shown him by Mr. Green of

the Tar Baby Mining Company and Mr. Barney of the Cardiff Mining

Company in South Fork, and at Alta by Mr. Blake of the Columbus

Consolidated, Mr. Lemmon of the Columbus Extension, Mr. Jacobson of

the Alta Consolidated, Mr. Godbe and Mr. Burton of the Michigan Utah,

Mr. Gabrielson of the South Hecla and Mr. Stillwell of the Emma. To

the managers and directors of these mines, the writer is grateful for the

privilege of visiting the various properties and studying the ore deposits.

To the several members of the Department of Geology at Columbia,

the writer feels greatly indebted for many helpful suggestions in the

preparation of the report. To Professor Amadeus W. Grabau is due

special thanks for the encouragement he has given from the very outset.

Throughout the laboratory work, and especially on the paleontologic and

stratigraphic side, he has manifested great interest in the results as they

appeared. His kindly criticism has been of much value and assistance

in formulating the conclusions here drawn. To Professors D. W. John-

son and C. P. Berkey, the writer is indebted for many valuable criticisms

relative to the physiographic and petrographic features of the work.

PHYSIOGRAPHY

ORIGIN OF THE WASATCH MOUNTAINS

Immediately following Cretaceous time, the present Great Basin prov-

ince was the scene of dynamic disturbances through which numerous

mountain ranges were formed by the processes of folding and overthrust-

ing. During early Tertiary time, the folds were truncated by erosion

88 ANNALS NEW YORK ACADEMY OF SCIENCES

and the surface was reduced to an aspect of low relief. Then followed a

period marked by profound faulting, the lines of movement being prin-

cipally in a north-south direction, but with many cross fractures, which

resulted in the formation of great fault-block mountains. These were

characterized by relatively simple external features but with complex

internal structure. The most easterly, and one of the most continuous

of these fault-block masses, is the present Wasatch range.

When newly formed, the Wasatch block had a steep western face and ‘a

long gentle eastern back slope. It was greatly elongated in a north-

south direction, extending from central Utah northward for almost 200

miles. ‘T’he width as measured from its fault face on the west to its

eastern border was about 25 miles. Its height was mainly due to vertical

displacement ‘along the great fracture line on the west. This dimension

was no doubt cumulative and due to periodic uplift, the aggregate throw

probably reaching 10,000 feet. The line of greatest elevation or crest of

the block was near the western margin.

DISSECTION AND DRAINAGE

The dissection of such a block must have been initiated by the conse-

quent streams which flowed down the two unequal slopes to the east and

west. ‘The valleys developed by these opposed streams would thus ba

transverse to the principal direction of the range, and when fully devel-

oped would divide it into a series of roughly parallel east-west ridges on

each slope, leading from the main divide to the two margins of the block

mountain. The unequal declivity of the two sets of streams would in

time cause a migration of the divide toward the center line of the block,

if the structure and materials were not essentially different and the base

levels were at the same elevation on both sides. If the base level on the

east were higher than the one on the west, the divide would come to rest

nearer the eastern border, and the valleys and ridges west of it would be

longest and most prominent. Some of the most powerful streams on the

west slope might even cut entirely through the divide and send out lateral.

subsequent tributaries that would capture the east flowing consequents

and lead them westward into the Salt Lake Basin. When once estab-

lished, these master streams would continue to push eastward into the

region beyond the Wasatch, gradually acquiring more and more drainage

territory.

In the light of these theoretical considerations, we may examine the

present maturely dissected Wasatch block mountain for some of the

larger features due to its original form and subsequent dissection.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 89

The main crest line of the Wasatch extends in a general north-south

direction and stands at a variable height of from 3000 to 8000 feet above

the level of the Bonneville Basin to the west. It is situated near the west-

ern border of the block and is marked by a succession of lofty peaks

which crown the western terminations of a series of ragged ridges that

lead westward from the main divide. This divide is situated from two to

six miles east of the crest line, being often nearer the eastern border of

the range than the western. This is especially noticeable in the central

Wasatch. Here the divide is also lower than the crest by more than a

thousand feet.

Hed

FIG. 1. STEREOGRAM OF A PORTION OF THE CENTRAL WASATCH MOUNTAINS, UTAH

NETSTAT,

Shows a maturely dissected block mountain with a steep western fault face and a

gentle eastward back-slope. The main gorges are Big and Little Cottonwood Canyons,

heading near the eastern margin of the block, and representing principally obsequent

stream channels.

To the east, a similar series of ridges and intervening gorges lead off

from the divide. A significant difference is to be noted here between the

slope of the tops of the ridges east of the divide and those to the west.

Kast of the divide, the ridges slope down to the level of high-lying basins,

while westward they rise to the crest line and then suddenly break off to

the Salt Lake plain. The tops of the ridges from the crest eastward

descend gradually to the divide, and, crossing over it, they continue to

become lower until they reach the eastern valley levels. They thus indi-

cate the original back slope of the block, though they do not preserve any

of the undissected upland surface. ‘The present eastward slope of the

ridge tops is not a very noticeable feature when viewed from the high

peaks on the crest, the inclination being but a few degrees and appearing

almost horizontal to the eye. From the more rapid erosion that has been

going on along the crest line, however, it is safe to infer that the original

back slope was of greater inclination, probably as much as 10 or 15

degrees.

90 ANNALS NEW YORK ACADEMY OF SCIENCES

The migration of the divide from the crest line toward the eastern

margin of the block is most pronounced in the central part of the range.

Big and Little Cottonwood canyons are good examples of long and deep

valleys pushed back from the western face of the range well toward its

eastern margin. The streams which have cut them have a more direct

course to the base level of the region than those on the opposite side of

the divide. This advantage has enabled them to send the divide east of

the center line, where it should be expected to come to rest if the stream

grades were equal in both directions (see Fig. 1).

At present, the Salt Lake Basin is the base level for the drainage of

the east slopes as well as the west. The two through going streams, the

Provo and Weber Rivers, bring the eastern drainage by long round-about

courses back into the Bonneville Basin. No special field work has been

done by the writer to determine the conditions which have established

these streams in their present courses, but the thought suggests itself very

strongly that they began as Big and Little Cottonwood creeks did to cut

headward, and being more successful penetrated far enough to capture all

of the eastern drainage of the central Wasatch and much of the western

Uintas and the plateau region to the north and south of the Uintas.

Their headwaters approach each other very closely at the western end of

the Uinta uplift and are here separated by a low divide near the southern

limit of the Kamas prairie. This divide becomes more pronounced as we

follow it westward, rising as a high ridge between Parley’s Park and

Provo, or Heber Valley, and eventually culminating in Clayton Peak on

the Wasatch divide, at the head of Big Cottonwood Canyon. The eastern

slope of the Wasatch in this neighborhood is thus drained by two river

systems which lead off in opposite directions, at length turning westward

and cutting across the Wasatch to the Bonneville Basin. The small con-

sequent streams which lead north-east and south-east from the Wasatch

divide on opposite sides of Clayton Peak have the disadvantage of a long

detour to the base level and have therefore been unable to cope with the

streams west of the divide which have a much shorter and more direct

course to the same base.

Structure and hardness of the rocks seem to have exercised only a

minor amount of control in the determination of the position of the

stream channels west of the divide. In Big Cottonwood Canyon, where

the hardest rocks of the region are exposed, the stream seems to have cut

indifferently across the beds in a peculiar diagonal fashion in the lower

half of its course. In the upper half, it has much less fall and follows

the strike of the beds more closely. The rocks here are limestones, shales

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 91

and sandstones, while in the lower and steeper part of the canyon they

pass into hard quartzites and slates.

It thus seems to be a fact that the structure and hardness of the rocks

in the upper part of the canyon have had a somewhat greater influence

on the course of the stream than in the lower part. Little Cottonwood

Canyon is developed for the most part in granite of a very hard and

homogeneous character. The course of the canyon is parallel to Big

Cottonwood, where both structure and heterogeneous rocks enter into the

problem. It is apparent that there must be some other cause operative

to produce the correspondence. The chief determining factor seems to

have been the original form of the block mountain. The western conse-

quent streams on the steep fault face developed their channels transverse

to the main north-south trend of the block, their direction being deter-

mined by the slope primarily. If the block was rapidly uplifted, the high

gradient of the streams would be quite sufficient to cause them to cut

back independent of the structure and kinds of rock. The direction of

back-cutting would be at right angles to the front of the block, and as

this was somewhat irregular, being curved in places, the stream courses

should show some irregularity in direction. This indeed is the case.

Where the fault face forms a great curve, as it does southeast of Salt Lake

City, the canyons show a marked tendency to take off in the direction of

the extended radii of the arc, as should be expected.

GLACIATION

After the Wasatch block mountain had been maturely dissected by

stream action as briefly outlined above, Alpine glaciation set in during

the Pleistocene period. Many of the deep V-shaped gorges were hollowed

out into broad U-shaped valleys of striking outline. The best known ex-

ample is Little Cottonwood, but there are many others in the upper parts

of the large canyons. The upper half of Big Cottonwood is a deep U-

trough with many hanging valleys on both sides. The heads of the can-

yons were widened into broad catchment basins with steepened sides.

The divides were greatly sharpened in many places. Altogether, the

topography was modified to a considerable extent in the central Wasatch,

especially at the higher elevations near the heads of the canyons.2. Nu-

merous lakes due to glacial damming and the plucking action of the ice

by which rock basins of considerable depth were formed are to be found

at the heads of the larger canyons. Good examples of roche moutonneés,

2For a map showing the location of the principal glaciers and their catchment basins,

as well as a brief account of the glaciation in the Wasatch, see ATwooD: U. S. Geol.

Surv. Prof. Pap. No. 61.

92 ANNALS NEW YORK ACADEMY OF SCIENCES

rock steps, and various other features due to glaciation are of frequent

occurrence (see Plate I, Fig. A).

Since the disappearance of the glaciers, erosion has been slight. The

streams have cut through the loose moraines in some places, but where

they have been flowing on solid rock beds, they have cut but faint notches.

These modifications are negligible as compared with the preglacial and

glacial erosion which produced mature dissection.

STRATIGRAPHY

INTRODUCTORY STATEMENT

The first works of importance on the general stratigraphical succession

in the Wasatch Mountains are those of the King* and Hayden* surveys

in the late seventies. They are to-day the only comprehensive account

that we have dealing with the great range of sediments there exposed.

Being general in their treatment, they have left many details to be sup-

plied by closer investigations, such as are carried on within smaller quad-

rangles where the necessary time is taken to work out structural problems

as well as to observe the general sequence of beds. American stratigraphy

offers many examples of the mistakes that are so easily made by follow-

ing the law of superposition without due regard to structure. Unrecog-

nized repetition of beds by folding and faulting has often led to serious

errors in estimating the real thickness and succession of formations.

Within the limited time that was allotted to the comparatively few

workers on these early surveys, a wonderful amount of field work was

done, and magnificent reports, well illustrated with maps and sketches,

were issued, which, though they are now known to be wrong in many

cases, still serve as the best introduction to the systematic geology of the

range.

In presenting a generalized account of the stratigraphy of the Wasatch

Mountains, the Fortieth Parallel geologists seem to have taken the sec-

tions which showed the thickest development of the rocks of the various

systems. The sections exposed in Weber Canyon and a few miles to the

north in Ogden Canyon, together with those found in Big and Little

Cottonwood Canyons, sixty miles to the south, seem to have been chosen

as the types for the Paleozoic rocks. Especially the latter seems to have

made a wonderful impression upon King, who introduces it thus: “I will

now give a section observed between the mouth of Cottonwood Canyon

3U. S. Geol. Expl. 40th Par., vols. I and II, 1877, and Vol. III, 1878.

4U. S. Geog. and Geol. Surv. of the Territories.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 93

and Parley’s Park, the most extended and instructive stratigraphic ex-

hibition of the Paleozoic series in the Fortieth Parallel area.” °

It now appears that the Ogden area, recently visited by Blackwelder®

and some of his colleagues from the University of Wisconsin, and the

Cottonwood Canyon district, covered by the writer last summer, are simi-

larly characterized by complicated structures involving large overthrusts

which duplicate the rocks of the lower members of the Paleozoic series

and give an apparent thickness which is much too great. Blackwelder

has shown that the Ogden quartzite of Hague and Emmons does not exist

as originally defined. Elsewhere in this report, it is shown that the Ute

Mill Creek Canyon

Big Cottonwood Canyon

NE A "ep

“ 3

y, 4 oe? - AY

‘ 4s by” y g

GPa 240 4 Lope 7, p ‘ Vs

OEP SP % if 44,744 yes Ae X97, ae: a3

2G 7277 Y, Y, ALi OO L- M B OLAS. SB

We Ra We Pus Pr Pwq’ B.O¢

FIG. 2, SECTION EXPOSED BETWEEN THE MOUTH OF BIG COTTONWOOD AND THE HEAD OF

MILL CREEK CANYONS

Al = Algonkian. C=Cambrian. O=Ordovician. D=—=Devonian. M = Mississip-

pian. Pwq=Penn. Weber quartzite. Pp=— Penn. Park City formation. Pws = Per-

mian Woodside shale. Tt= Triassic Thaynes formation. Ta— Triassic Ankareh shale.

Jn= Jurassic Nugget sandstone.

limestone of supposed Silurian age also has no existence as such in the

central Wasatch, but is in reality the lower part of the Wasatch limestone

reported as belonging to the Carboniferous. It seems strange that this

relation should not have been discovered by the early workers on account

of the marked contrast between the sequence of beds near Alta in Little

Cottonwood Canyon and that seen across the divide to the north in Big

Cottonwood Canyon.

BIG COTTONWOOD SECTION

At the mouth of Big Cottonwood Canyon is exposed the base of the

great section of Paleozoic and Mesozoic rocks above referred to by King.

Beginning on the strike of the beds which stand at a high inclination

5C. KING: U. S. Geol. Expl. 40th Par., Sys. Geol., Vol. I, p. 165. 1878.

®E. BLACKWELDER: “New Light on the Geology of the Wasatch Mountains, Utah,”

BullG S.A. Vol, 21, pp: bL7-b42.- 1910:

Q4 ANNALS NEW YORK ACADEMY OF SCIENCES

(dip N. 60°), the great canyon holds a general course N, 70° EH. for

nearly eight miles, slowly truncating the edges of the successively higher

beds, which as we go east gradually change their strike toward the south.

From its mouth for a distance of about six miles, the canyon is walled by

brown and yellowish quartzites interspersed with thick beds of black and

purplish blue slates. The upper six miles of the canyon show the post-

Cambrian formations, the general continuity of the beds being seriously

broken only at one point, opposite South Fork of Mill D. The top of the

section passes beyond the northeast divide of the canyon into the north-

west corner of the Park City district.

QUARTZITE-SLATE SERIES

The great quartzite and slate series is succeeded below by gneiss and

schist or granite. The igneous nature of the granite contact was not rec-

ognized by the Fortieth Parallel geologists, who mapped the granite as

Archean and described the contact as one of sedimentary unconformity.

The quartzite succession was assigned to the Cambrian, including the

lowermost exposures. In describing the rocks referred to the Cambrian -

in his recapitulation of the Paleozoic, King’ says:

“Thus far among the reported occurrences of the rocks of this horizon in the

Cordilleras, the locality at the mouth of Big Cottonwood Canyon must remain

as the finest example and the stratigraphical type. The lowest member—the

Cottonwood slates, a group about 800 feet thick, which here rests upon highly

metamorphic Archean schists—has thus far yielded no organic forms. The

rocks are dark blue, dark purple, dark olive green and blackish argillites, all

highly silicious and as a group sharply defined from the light-colored quartzite

schists which conformably overlie them. This second group, by far the greatest

of the whole Cambrian series, is a continuous zone of schists which have a

prevailing quartzite character, though varied with considerable amounts of

argillaceous matter. From 8000 to 9000 feet thick, it has a general uniformity

of lithologic condition from bottom to top. . . . The prevailing colors of

this member are gray, greenish gray, drab and pale brown, never dark colors.

Conformably overlying it are 2500 to 3000 feet of cream and salmon color and

white quartzites and quartzofelsites. Occasional sheets of conglomerate are

seen in the quartzites not far below the summit of the Cambrian.”

A few years later, in the course of his studies of the Cambrian sections

of the Cordilleras, Dr. C. D. Walcott® visited Big Cottonwood Canyon,

examining the quartzite series in more detail and re-measuring the sec-

7™C. Kina: U. S. Geol. Expl. 40th Par., Vol. I, pp. 229-230. 1878.

8C. D. WaLvoTTr: “Second Contribution to the Studies on the Cambrian Faunas of

North America,” Bull. U. S. Geol. Surv. No. 30, pp. 38-39. 1886.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 95

tion. Walcott’s section® is invertedy as originally published, and is here

given in the natural order, as follows:

Big Cottomwood Section

Feet

14. Superformation: Mixed sandy and calcareous rocks which rest con-

formably on 138 of the section and carry a fauna which refers it

to the lower Silurian (Ord).

13. Hard, silico-argillaceous shales, a little sandy in places............. 250

Fossils: At the base, Cruziana sp. associated with Olenellus

gilberti; 100 feet higher up, a band of shale afforded Linguella

ella, Kutorgina panula, Hyolithes billingsi, Leperdita argenta,

Ptychoparia quadrans and Bathyuriscus producta.

Pesta y GOMpPACL GQUATUZILIC SANGSTONE: 6.0.60 cee ee Stk cee ec we eacae 3,000

11. Purplish and reddish brown quartzitic sandstone...............0... 75

Pe fea COMpACt-OUartAZILiC: SANGStONE. ..ou0 ce ase aN else Seles cle cweeneceses 700

9. Black, sandy, arenaceous, slightly micaceous shale................. 15

8. Light gray quartzite and quartzitic sandstone, in layers varying from

10 feet to 2 inches, the thin layers occurring as partings between

the more massive bands of layers. In some places, the quartzitic

sandstones show grains, and in others they are lost. Stains of

purple, iron rust, reddish brown and buff color occur............. 2,700

. Arenaceous and argillaceous slates, black, bluish black, drab and

yellowish green. The exposure is extensive, the opportunity for

finding fossils excellent, and the slates afford a beautiful matrix

for their preservation, but none were oberved...............c.cece. 700

6. Light gray quartzite and quartzitic sandstone, in layers varying from

10 feet to 2 inches. In some places, the quartzitic sandstones show

grains, and in others they are lost. Stains of purple, iron rust,

Remit, PEOW iN 4200 WU COOP OCCU arc <0 «acs wie ole, se is éataleva eons oie 200

5. Hard, black, arenaceous shale, with specks of mica on the surfaces.

Quartzite and shale intercalated near the base.................2.. 1,000

4. Light gray quartzite and quartzitic sandstone in layers, varying from

10 feet to 2 inches. In some places, the quartzitic sandstones show

grains, and in others they are lost. Stains of purple, iron rust,

Festian, bowie nO” Bile (COlOT (OCCII oss ccc ce x vie aoc ce eles ae os tba e ns 700

3. Purplish, thin bedded sandstone, with bands of greenish yellow argil-

PICeOte ssh ee Nene TAGeSTMMNING s. f<cs decchs Sec ss hale eles s ce tau esaee 700

meniaosive peaued Ment bay QUATIZIEC. i ce ksh wale be eee lee ees 1,000

1. Black arenaceous shale, showing mud-markings and mud cracks,

Ce UT DEO DI GIT S| Rak MESES TS ee ee eer ee ee 900

eM OMe te ya ce LY w leha a./e nares sarepale 54K xc aere &, alate tate 12,000

Age of Series

From the occurrence of the Olenellus fauna in the shale member at the

top of the series and the apparent conformity of the entire succession of

® The section is given here as corrected by Dr. Walcott in his Correlation Papers, Bull.

U. S. Geol. Surv. No. 81, p. 319. 1891.

96 ANNALS NEW YORK ACADEMY OF SCIENCES

quartzites and shales, Walcott was led to place the whole 12,000 feet of

strata in the Lower Cambrian. The Fortieth Parallel geologists, reason-

ing that the granite at the base was pre-Cambrian in age and separated

from the quartzite series by a great unconformity, also assigned it to the

Cambrian period, It is significant that the description given by King of

the upper part of the section includes sheets of conglomerate, which, how-

ever, Walcott does not mention. ‘These occur in a succession of coarse

sandstones, the individual pebbles being small, usually less than half an

inch in diameter. Blackwelder?’ has called attention to the strong litho-

logical resemblance of these pebbles to the bright colored quartzites far-

ther down in the series. He has also pointed out the fact that the section

which is here 12,000 feet thick is much thinner to the north and that it is

subject to rapid variations of thickness within short distances. ‘These

facts are taken to suggest the existence of an unconformity within the

quartzitic series. At a horizon roughly estimated to be 1500 feet below

the top of the quartzite in Big Cottonwood, Blackwelder reports the ex-

istence of a well-marked basal conglomerate, which he represents as lying

upon the truncated edges of the lower members, showing, however, little

angular discordance between the two sets of beds. ‘This old erosion sur-

face is taken as the base of the Lower Cambrian, marking the separation

of the Cambrian from the Algonkian.

At the head of South Fork, near the Rexall mine, the writer found a

heavy conglomerate composed of large, well-rounded quartzite and gneiss .

bowlders lying upon a very black rock of strange characteristics, the de-

scription of which will be given later. Overlying the conglomerate are

700 feet of well-bedded white quartzite, showing several sheets of fine

conglomeratic material. Above this quartzite is a shale 125 feet thick,

and superjacent to this comes the lowest limestone series. Tracing the

conglomerate northward, the underlying black formation gradually thins

out and the conglomerate comes to rest on the next lower bed of white

quartzite. Passing west of Kessler’s Peak, this contact travels down the

east face of Mineral Fork and crosses Big Cottonwood Canyon, where

Blackwelder saw it, a short distance below the Maxfield mine. Maintain-

ing a fairly constant distance below the top of the series, the contact rises

rapidly on the north wall of Big Cottonwood Canyon and crosses the

divide into Neff’s Canyon just south of the head of that basin. Curving

gradually to the west, it crosses the crest of the range near the head of

Tolcats Canyon and descends rapidly to the base of the mountain in Salt

Lake Valley. From the starting place at the head of South Fork, it may

10, BLACKWELDER: “New Light on Geology of Wasatch Mountains, Utah,” Bull.

G. S) AS Voll 21, 0.1520, Aono:

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 9Y

be traced southward through the Alta basin at the head of Little Cotton-

wood Canyon, into American Fork Canyon.1°¢ At Santaquin, near the

Union Chief mine 40 miles to the south, it is seen again, being there 600

feet below the top of the series. The black formation on which it rests at

the head of Little Cottonwood Canyon seems to be absent everywhere

within a few miles to the north and south of that place, not appearing in

Big Cottonwood Canyon, nor at Santaquin to the south. From its occur-

rence thus traced for about 50 miles, it may safely be taken to be of wide

distribution. That it truncates the lower beds, producing extraordinary

differences in their thickness within short distances, is also clear from the

rapid disappearance of the black member, above referred to, and from the

fact that northward at Willard, Utah, the conglomerate rests directly on

Archean gneiss. The possibility of original inequality of thickness must

be taken into account in connection with the thinning of the lower series.

The uniform thickness and wide distribution of the quartzite and shale

member overlying this dividing plane, taken together with the great vari-

ation in thickness of the lower series, seem to imply the widespread trun-

cation of the lower beds and their reduction practically to a peneplain

before the upper beds were deposited. The complete removal of the great

quartzite series over considerable areas must have required much time.

A great gap therefore separates the Lower Cambrian quartzite at the top

of the series from the great quartzite and shale series underlying it, and

the two must be of distinctly different ages.

Accepting Walcott’s fossil evidence of the presence of Lower Cambrian

strata above the unconformity, it seems only proper to regard the quartz-

ite-slate series below as of pre-Cambrian, and probably Algonkian age.

It would then correspond to the Belt series of Montana and the Grand

Canyon series of Arizona, in both of which the Cambrian strata are sepa-

rated from the pre-Cambrian formations by similar unconformities.

A very different view is held by Daly and others, namely, that the oldest

Cambrian fossils in the Rocky Mountains are Middle Cambrian and that

the Brigham quartzite is of that age. The unconformity is regarded as rep-

resenting only a brief time interval, and the great quartzite-slate series is

made early Cambrian and not Algonkian in age. This view seems to call

into question the faunal evidence upon which the presence of Lower Cam-

brian strata at the top of the series is based. Dr. Walcott very kindly

supplied the writer with photographs of two specimens of Olenellus gil-

berti, which he found at the base of the shale bed, and there seems to be

no reason to doubt their correct identification. A diligent search in all

10q. See Plate I, fig. B.

98 ANNALS NEW YORK ACADEMY OF SCIENCES

the shale beds by the writer was not rewarded by the discovery of Cam-

brian fossils within the Cottonwood district. At Ophir, in the Oquirrh

Mountains, and at Santaquin, the Middle Cambrian fauna which Dr.

Walcott found 100 feet above the Oienellus fauna in Big Cottonwood

Canyon are also found, and at least in one place at Ophir in the same

relation to the Lower Cambrian fossil horizon. A later search at Santa-

quin may reveal the Olenellus fauna there. |

If we accept Olenellus gilberti as the index fossil of the Lower Cam-

brian, then it seems that Daly must be mistaken in the statement that that

z Willard, Box Elder Co

® Big Cottonwood Canyon

FIG. 3. SECTION FROM BIG COTTONWOOD CANYON NORTHWARD TO WILLARD,

BOX ELDER CO., UTAH

Relation of the Algonkian (AL) slate and quartzite series to the Archean (AR) gneiss

and schist, and the Cambrian (C) quartzite and shale

horizon is not represented by the Brigham quartzite and part of the over-

lying shale. That the shale beds of the great quartzite series below the

unconformity have yielded no fossils after careful searching by many

workers seems to argue against their Cambrian age. It is conceded by

everyone who has seen them that the shales are well enough preserved to

show good fossils, if any had been imbedded in them. ‘There is, of course,

still the possibility that fossils may yet be found in these lower shales, but

the probability is not great. That the unconformity represents only a

brief interval of time seems also to be incorrect from the manner in which

it is disposed over the truncated edges of the lower series, as represented

in the accompanying diagram, Fig. 3. |

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 99

The variation of thickness of the Algonkian rocks might be accounted

for in still another way. If they were laid down upon an irregular sur-

face, filling up the valleys and thus reducing the relief, the surface upon

which the Cambrian beds were laid down later might be relatively smooth

and their uniform thickness would be accounted for, as well as the change-

able thickness of the lower formations, but the relation of the beds above

the unconformity to those below would be different. There would have to

be practically no truncation of the lower members; the relation would be

more nearly that of a disconformity, and the separation of the two series

would be much more difficult on account of the lack of discordance. 'The

advancing Lower Cambrian sea would rework the surface materials and a

gradual transition would be established. Moreover, the close resemblance

of the large rounded quartzitic bowlders in the conglomerate to the under-

lying quartzites is strong evidence that they were derived from them by

stream erosion. This implies that the lower series was consolidated info

hard sandstones before the invasion of the Cambrian sea, an inference

which points to the much greater age of the lower quartzites. It seems,

therefore, only possible to account for the great variation in thickness of

the Algonkian rocks by erosion, before the deposition of the Lower Cam-

brian sediments upon their bevelled edges.

Relation of Algonkian to Archean

The relation of the Archean rocks to the Algonkian is not shown in the

Cottonwood region. The base of the Algonkian series is not exposed.

From its relation elsewhere, an unconformity doubtless exists and has

been represented in the figure above given. The Archean oldland may

have been devoid of relief but probably had some low monadnocks in

places. If the Algonkian rocks are continental in origin, as is generally

believed, the surface upon which they were deposited must have-been rela-

tively low and flat. The spreading fans and deltas of the Algonkian

rivers slowly extended themselves and covered the surface of the Archean

rocks, An unconformity, then, with overlap away from the source of sup-

ply, must separate these pre-Cambrian formations from the underlying

Archean.

The highest member of the Algonkian in the Cottonwood region is a

rock of somewhat unique characteristics. It is exposed at the head of

South Fork and may be traced south into American Fork Canyon but

soon disappears by overlap of the Cambrian beds. It has not been found

in any other part of the range, but upon one of the islands of Great Salt

Lake a rock of similar occurrence is found. The peculiar nature of the

100 ANNALS NEW YORK ACADEMY OF SCIENCES

deposit consists of the extraordinary distribution of large and small

bowlders within a rock which is otherwise fine enough to be classed as a

shale or very fine sandstone, The unusual occurrence of the scattered

bowlders of different sizes calls for a special explanation. Dr. Fred J.

Pack of the University of Utah has suggested a glacial origin for the

bowlders that occur in a similar fine-grained black rock on Stansbury

Island in Great Salt Lake. At that place, they show facetting suggesting

ice erosion, though glacial striz have not been seen. In the Cottonwood

deposit, the bowlders are of greatly varying sizes, from small pebbles to

blocks weighing several tons. The smaller ones show water action in that

they are much rounded, but the extremely large ones are distinctly angu-

lar. It is difficult to imagine how such masses came to be imbedded in a

rock which is otherwise so uniformly fine grained, unless we appeal to an

agent like ice which has the power to carry them long distances and de-

posit them without changing their form to any marked extent. Ice-

rafting might be suggested as a possible means for their irregular distri-

bution. Facetting and more or less complete rounding of the smaller

pebbles would also be conceivable on such an hypothesis. In fact, the

heterogeneous nature of the deposit is one of the strong factors in support

of the supposed glacial origin (see Plate IT).

In the March number of the American Journal of Science for 1907,

Coleman,” after a brief review of the reported occurrence of Paleozoic

ice ages in many parts of the world, suggests the probable existence of a

Lower Huronian ice age:

“For several years, it has seemed to me very probable that there was a still

more ancient ice age, at the beginning of the Lower Huronian in the Archean

as defined in Canada or the Archeozoic or lowest Algonkian as defined by

various American geologists. The so-called Huronian ‘slate conglomerate’ of

Ontario has attracted attention ever since Logan and Murray mapped and

described it in the typical region north of Lake Huron nearly fifty years ago.

Good descriptions of it are given by Logan in the 1863 report of the Canadian

Geological Survey; where he refers to the different kinds of rock inclosed as

pebbles or boulders, granite, felsite, certain green-stones and jaspers, for ex-

ample; and describes the matrix as sometimes slaty, sometimes more quartzitic

or like diorite or green-stone. At present the matrix would be called gray-

wacke or slate though sometimes it is schistose or looks like an eruptive rock.

“The pebbles are in many cases subangular or sharply angular and are

found miles away from any known source; and as they may be of any size up

to blocks weighing tons, and are frequently very sparcely scattered through

an unstratified matrix, a stone or two in several yards, one cannot help suspect-

ing that the transporting agency was ice rather than water.”

11 Personal communication.

122A, P. CoLEMAN: “A Lower Huronian Ice Age,” Am. Jour. Sci., Vol. 23, p. 187.

1907.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 101

Coleman sums up the evidence for a Lower Huronian ice age as

follows:

“A peculiar rock consisting of graywacke or finer material showing little

or no stratification but containing pebbles or stones sometimes crowded but

more often scattered a few feet apart, is found from point to point over an

area S00 miles long by 250 miles broad. The stones are of all sizes up to

diameters of several feet and of all shapes from rounded to angular, many

being subangular with rounded corners. The stones are of several different

kinds, some fragments of immediately underlying rock, others having a distant

source.

“In the Cobalt region a few polished and striated stones have been broken

out of the matrix. ‘They are closely like the Pleistocene boulder clay of the

same region except that they lack the Niagara limestones of the recent drift.

“Hand specimens of matrix and enclosed pebbles are precisely like the

Dwyka tillite or conglomerate of South Africa which is undoubtedly of glacial

origin.”

It is obviously impossible to connect these deposits in eastern Canada

with those of the Cottonwood area in Wasatch Mountains, without some

surer means of correlation than lithological similarity. If, however, we

accept Coleman’s evidence, the occurrence of glaciation is probable over

an area which is much too large to be attributed to local mountain gla-

ciers. The two Utah occurrences are 60 miles apart and were undoubtedly

of much wider distribution, having been removed by erosion previous to

the deposition of the Cambrian beds, as previously explained. It is highly

probable that these exceptional sediments are to be explained on the same

basis, and that suggested by Coleman deserves serious attention and may

be accepted at least for the present. An ice age of sufficient duration to

manifest itself over such a large area in eastern Canada might easily be

expected to register its effects in the western part of the same continent,

especially at approximately the same latitude and northward.

Mr. E. L. Bruce, a member of the Canadian Geological Survey who has

seen the rocks as they occur in Canada and also the writer’s material, says

that they are strikingly similar in almost every detail. The description

quoted above from Coleman’s article applies equally well to the black rock

at the head of South Fork in Big Cottonwood Canyon. If we accept them

as glacial deposits, they are probably of the same age, and the quartzite-

slate series in the Wasatch and Uinta mountains is much older than has

been thought up to the present time. From the obvious scientific impor-

tance of establishing the existence of an ice age in that early period of the

earth’s history, the question deserves further careful study.

102 ANNALS NEW YORK ACADEMY OF SCIENCES

Origin and Nature of the Algonkian Sediments

The nature of the Algonkian rocks has already been partly discussed

and a very general description given in the sections by the Fortieth Paral-

lel geologists and Dr. Walcott. These may be briefly summarized as fol-

lows: The prevailing rocks are quartzites and interbedded shales, the

quartzites being mostly hght colored, white and yellow to light brown;

the shales, dark purple and green to black. ‘Toward the top of the series,

thin sheets of conglomerate occur in the quartzites, in which small well-

rounded pebbles of quartz and quartzite are abundant. In a dark shale at

the base of the series, mud cracks are abundant, ‘To these characters may

be added several others observed by the writer and also mentioned by

Blackwelder. The quartzites are often prominently cross-bedded, the dis-

cordant angularity of the beds being usually of small amplitude. Ripple

marks of the long parallel type are often common in the sandy shales.

Limestones are totally absent, and though conditions favorable to the

preservation of fossils seem to be abundant and right, no organic remains

have been discovered.

From the intermediate geographical location of the Big Cottonwood

section with respect to the Grand Canyon section on the south and the

many occurrences of thick pre-Cambrian sediments to the north in Idaho

and Montana, and from the fact that many of the above mentioned fea-

tures of the Wasatch Algonkian have also been recorded from these other

localities, it seems logical to suppose that they must have the same or a

very similar origin. Upon whatever basis one is explained, the rest will

probably also be explicable. Limestones and dolomites are met with in

the northern and southern series and show that those regions had more

varied conditions of sedimentation, involving periodic inundations of the

sea, unless they are of fresh water origin. The major portions of the

rocks are, however, clastic sediments and show physical characteristics

which point to a continental origin. Shrinkage cracks and ripple marks

in the shales and shaly sandstones indicate extensive mud flats comparable

to the flood plains of many of our large rivers. Cross-bedding of the type

here found suggests shifting water currents such as those of terrestrial

rivers rather than wind. So that if we postulate a river origin for most

of the quartzites and shales, we have at once a complete explanation of

the physical characters already noted and the conspicuous dearth of fos-

sils. Barrell’* argues for the dominant flood plain origin of mud cracked

13 J. BARRELL: ‘‘Geological Importance of Sedimentation,” Jour. of Geol., Vol. XIV, pp.

553-568. 1906.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 703

formations. Subaérial deposition in an arid region would also account

for the highly oxidized character of most of the beds. While a final con-

clusion must be reserved for future more extended studies, the presump-

tion from the facts at hand is in favor of a continental origin for all of

the Wasatch Algonkian and a large part of the Arizona, Idaho and Mon-

tana occurrences.

We may now inquire into the probable situation of the Archean old-

land from which these sediments were derived. It is clear from the gen-

eral distribution of the Algonkian rocks above referred to in a north-south

belt from Arizona, through Utah, Idaho and Montana into British Colum-

bia, that the source must have been to the east or west. If we examine the

sections to the eastward, we find that as we approach the north-south line

of the Front Range, these pre-Cambrian quartzites thin away and disap-

pear, and we have late Cambrian strata resting with unconformity upon

Archean rocks. It appears then that here we have an area which was

actively eroded during Proterozoic and most of Cambrian time and that

did not become an area of deposition until late Cambrian time. From the

general absence of Lower Cambrian formations in. this region and their

presence in the Wasatch Mountains and westward in Nevada, it is clear

that the Cambrian sea came in from the west. This seems to indicate the

absence of any considerable land mass to the west and reduces our source

of supply to the eastern oldland. We may then consider the continental

divide to be the Archean axis of the Front Range in Colorado and its

northward extension into Canada, from which the rivers flowed to the east

and to the west. Those draining the western slopes of this Archean eleva-

tion opened out upon lowlands in central and eastern Utah and to the

north and south. Here subaérial deposition began in the formation of

great fans spreading westward and becoming more or less confluent toward

the north and the south.

CAMBRIAN STRATA

The base of the Cambrian strata is now drawn at the unconformity

above described. The separation of the rocks from the much older Algon-

kian formations has reduced their thickness from 12,000 feet, as formerly

estimated, to less than 1000 feet.

The lowest Cambrian formation is a conglomeratic quartzite 700 feet

thick. No fossils have been found in it, and its age is fixed by its position

above the well marked unconformity and below the succeeding shale bed

carrying the Olenellus fauna, At the base lies a heavy conglomerate com-

posed of rounded pebbles and bowlders of quartzite and gneiss and the

104 ANNALS NEW YORK ACADEMY OF SCIENCES

black conglomerate already referred to as occurring at the head of South

Fork. The conglomerate is nowhere of very great thickness, being usually

less than 10 feet. Within the lower 200 feet of the succeeding quartzite

are several sheets of fine conglomerate, the pebbles being quartz and

quartzite. The remaining 500 feet are of coarse white quartzite which

weathers to a light yellow or cream color. It is well bedded into layers

varying from a few inches to several feet in thickness. 'Toward the top,

the beds become uniformly thinner and gradually pass into shale, the

latter being intercalated between the thin sheets of quartzite. Hanging

from the under side of several quartzite layers in this transition zone are

curious Arthrophycus-like structures. The sandy shale layers show well-

preserved ripple marks of the parallel types, proving the shallow water

origin of these sediments and their transitional character.

A similar quartzite formation is of wide occurrence in the Wasatch

Range to the north and south and in the Basin ranges to the west. It is

everywhere very similar in its appearance and physical characteristics and

is followed by a dark shale of Lower or Middle Cambrian age. From its

occurrence near Brigham City, Utah, Walcott has called it the Brigham

quartzite, and though it is better shown at Willard and several other

places along the range, we may retain the original name to avoid repeti-

tion. In Big Cottonwood Canyon, it is well exposed just below the old

Maxfield mine and may be seen on both walls of the canyon. Southward,

it becomes the east wall of Mineral Fork, underlying the limestone and

shale which form the capping of Kessler’s Peak. Dipping to the north-

east, it cuts across the head of South Fork and crosses the divide into

Little Cottonwood Canyon just north of Alta.

Overlying the Brigham quartzite, just at the Maxfield mine, is a dark

micaceous, sandy shale, which, from its prominence just at the little town

of Alta, we may call the Alta shale. It rests conformably on the Brigham

quartzite with which it is in bold contrast on account of its black color.

It is somewhat variable in thickness, ranging from 150 to 200 feet. From

a sandy character near the base, it passes slowly into a thinly bedded, fine-

grained shale in the middle and upper part, representing a continuous

depositional unit. From two horizons within the Alta shale, 100 feet

apart, Walcott?* reports the following Middle and Lower Cambrian fauna

from Big Cottonwood Canyon:

144(°.. D. WALCoTT: U. S. Geol. Surv. Bull. No. 81, p. 319. 1891.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 105

Lingulella ella

Kutorgina pannula

Middle Cambrian....... Hyoliehes billingst

Leperditia argenta

Ptychoparia quadrans

-Bathyuriscus producta

{ Olenellus gilberti

)Cruziana sp.

Rewer Cambrian:.:.<:...

Dr. Walcott continues: “As in the Eureka and Highland Range sec-

tions, the Olenellus zone is confined to a very narrow belt just above the

quartzite. The silico-argillaceous shales (Alta) above occupy the position

of the 4650 feet of Prospect Mountain limestone and Secret Canyon shale

of the Eureka section. The Hamburg limestone and Hamburg (Dunder-

burg) shale of the latter are absent in the Big Cottonwood section, caus-

ing an unconformity by non-deposition. The section in the Oquirrh range |

above Ophir City has a quartzite at the base with shales above it carrying

Tingulella ella, Olenellus gilberti and Bathyuriscus productus, as deter-

mined by the collections brought in by the Wheeler survey. It is prob-

able, however, that as in the case of the Big Cottonwood section, Olenellus

gilberti occurs at the base of the shale, and the other two species at a

higher horizon.”

From this, it appears that the Middle Cambrian is only represented by

the middle and upper part of the Alta shale, and the Upper Cambrian is

wanting altogether. There exists, therefore, within the shale a discon-

formity between the Lower and Middle Cambrian strata and at the top a

great hiatus representing the entire Upper Cambrian series.

ORDOVICIAN STRATA

Disconformably overlying the Alta shale is a limestone and shale series

of which the following section, measured at the south end of the Reade

and Benson ridge at the head of South Fork, is typical:

Section in South Fork

Feet

13. Alternating blue shale and limestone conglomerate in beds 1-6 inches

Cob SLs Gus ety gtd a: eh Re SI ie ane a mr Cre em se Ree 10

12. Alternating shale and limestone, passing into shale.................. 20

enews PaMmaa My BEANE OST ONE THESIS) ihe dic a a oe Siw slo kc wae Cole Ais cw eidaludeeeeuwwten ee 6

10. Dark blue thin-bedded limestones, partings exceedingly irregular..... 55

9. Dark blue heavy bedded limestone with a wormy appearance, holes far

Og DEG SG Ye Pe eine ee) ee a ee rae geen eRe POP Ce Bae TAY 7 45

106 ANNALS NEW YORK ACADEMY OF SCIENCES

Feet

7. Dark blue wormy looking limestone greatly resembling typical bird’s-

eye limestone of ‘the east. 7.ad..c kee oe ee eee ee ee 85

6. Thin-bedded brown shale, strongly jointed toward the top............ 60

». Kinely intercalated, limesand! Shaleciite actus eee ee eee ee 10

4.. Light blue streaky limestone, weathers white: ............02:....c6-- 15

3. Blue heavy bedded limestone with wormy appearance toward top..... 60

2. Brown shale, blocky appearance from extreme jointing............... 75

1. Blue limestone intercalated with seams of clay giving a banded ap-

POATATICE 6 a5 win ie at 2 LE Rie ee eek ere eae Done eee ete eo 30

fe’ 2) er ee eee eNom srt si rhe rcs ae A as add ck 481

Subftormation: ‘Alta. shale.-c. 2 2.8 2s ci sae eer ee eee eee ee oe 200

No fossils were found in the beds of the above section, but the ramify-

ing tubes in the “wormy” looking members are very suggestive of some

form of life. Placed side by side, it is difficult to detect any appreciable

difference between the specimens of the Ordovician Bird’s-eye (Lowville)

limestone of New York and those taken from this section. Within this

part of the Wasatch, this character is a constant one and is a striking fea-

ture by which the rocks of this horizon can always be told. Though it has

afforded no fossils within the area studied, it is interesting as representing

the first limestone making period of this region. No coarse clastics occur,

and the series belongs essentially to the off-shore facies, where conditions

of sedimentation were constant for considerable lengths of time, but on

the whole subject to quite frequent change. 'The period is brought to a

close by a withdrawal of the sea and exposure of the surface to erosion.

The limestones of this new land area were broken up and worn round,

typically lens-shaped, and deposited in a curious helter-skelter fashion

with many of the flat pebbles standing on edge. Hand specimens taken

are almost identical in appearance with those described and illustrated by

Blackwelder?® from China. Intra-formational conglomerates from the

Lower Ordovician have also been reported from Pennsylvania.’® In the

Lakeside Mountains, west of Great Salt Lake, there is a bed of similar

limestone conglomerate of considerable thickness belonging to the Beek-

mantown horizon. While the age of the beds below the “edgewise” con-

glomerate of the above section cannot be told definitely because no fossils

were found in them, they are referred provisionally to the Ordovician.

They are of special interest because the largest ore deposits of the region

have been found in them. The rich galena bedded vein of the Maxfield

16}, BLACK WELDER: Research in China, Vol. 1, Part 2, pp. 384-390.

16G, W. STosE: U. S. Geol. Surv. Folio 170. 1910.

T. C. Brown: “Notes on the Origin of Certain Paleozoic Sediments,” ete., Jour. of

Geol., Vol. XXI, pp. 232-250. 1913.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 107

property at Argenta, in Big Cottonwood Canyon, is a good example, and

from this occurrence the name Maxfield formation is suggested for the

series.

SILURIAN STRATA

The presence of Silurian strata in western America was doubted for a

long time. It has recently been shown by Kindle,*’ however, that the

Silurian period is represented in a number of widely separated regions,

and among them, in the northern Wasatch. In Green and Logan Canyons,

east of Cache Valley, Cache County, Utah, Kindle reports the following

fauna obtained by F. B. Weeks:

Favosites gothlandica Lamark

Favosites niagarensis Hall

Halysites catenulatus Linn.

Zaphrentis sp.

Pentamerus oblongus Sow.

Below the Paradise limestone which carries these forms, there is a dark

colored limestone of undetermined age, Above it there is a dark magne-

sian limestone 800 to 1000 feet thick, carrying Devonian types. How far

the Silurian strata extend toward the south is not known. Blackwelder

reports limestones 1000 to 1500 feet thick in the northern Wasatch, on

the west side of Cache Valley, which lie between the Geneva formation of

Ordovician age and the identifiable part of the Mississippian. In the

lower part of this limestone series occur Halysites and Favosites, and a

brachiopod fauna somewhat higher up is thought by Kindle to be the same

as his Pentamerus fauna of the Bear River range.

From the occurrence of these limestones at Ute Peak, near the southern

end of Cache Valley, the Fortieth Parallel geologists gave the name Ute

limestone to the Silurian strata of the Wasatch region. Special mention

was made of the occurrence of this member at Alta, in Little Cottonwood

Canyon, where a limestone 1000 feet thick is boldly exposed above the

Cambrian shale on the north side of the canyon. Above this so-called

Ute limestone, and separating it from the higher limestone series known-

as the Wasatch limestone, are nearly a thousand feet of quartzite and

shale, mostly quartzite, which were called Ogden quartzite from their

somewhat greater development in Ogden Canyon. The Ute limestone

thus appears as a stratigraphic unit between two well-defined quartzite

formations in its typical occurrence. In the latter part of this report, it

7H. M. Kinde: “Silurian Fauna in Western America,’ Am. Jour. Sci., 4th Ser.,

Vol. 25. 1908.

108 ANNALS NEW YORK ACADEMY OF SCIENCES

is shown that the so-called Ogden quartzite is an overthrust block of

partly Algonkian and Cambrian quartzite and shale, lying upon limestone

of Devonian age. Blackwelder has recently shown that the same relation

exists in Ogden Canyon and that the Ogden quartzite does not exist as

originally defined. It now appears that the typical Ute limestone also has

no existence as a regular depositional unit but is in reality the lower part

of what was called the Wasatch limestone. The name Ute limestone,

therefore, must go the way of the Ogden quartzite and be discarded. The

Fortieth Parallel section is thus reduced over 3000 feet in thickness by

the elimination of these two members. No name has yet come into gen-

eral use for the Silurian strata of the northern Wasatch as they have been

little studied, but the one employed by Blackwelder, viz., Paradise lime-

stone, might serve. In the central Wasatch, this is apparently wanting

altogether.

The absence of Silurian strata in the central Wasatch may be due to

non-deposition or to their complete removal by erosion. The only evi-

dence of a great erosion interval in this part of the section is that already

mentioned at the top of the Maxfield formation. Limestone conglom-

erates, however, are looked upon with suspicion as forming true basal

beds since the discovery of the intra-formational types. Nevertheless,

there is no reason why this could not be a basal conglomerate upon an old

erosion surface, for limestones of Lower Ordovician age are of wide dis-

tribution in the west.

DEVONIAN STRATA

Below the lowest Productus horizon of the Mississippian in the Cotton-

wood region occurs a cherty limestone in which there are abundant corals

of a few species. Fossils apparently from this horizon were reported by

Professor Sanborn Tenny*® of Williams College as early as 1873. He

described the locality as follows:

“In a position southeast of Great Salt Lake City on the divide between

Great Cottonwood and Little Cottonwood, 9,000 feet to 10,000 feet above sea, is

a dark blue limestone, containing corals.”

The corals collected were two species of Zaphrentis and one of Syringo-

pora, which R. P. Whitfield called Syringopora maclurei Billings but re-

garded as probably a new species. These were roughly referred to the

Upper Helderberg horizon.

Little attention, apparently, has been given to the paper by Professor

18S. TENNY: “Devonian Fossils from the Wasatch Mountains, Utah,’ Am. Jour. Sci.,

3rd Ser., Vol. 5. 1873.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH | 109

Tenny, for Devonian strata have generally been held to be absent in this

part of the range. Boutwell,’® in his report on the Park City district,

says that Devonian fossils have only been found in the northern part of

the Wasatch range, and the formation in which they occur has been with-

drawn from the Wasatch limestone and correlated with the Jefferson

limestone.

Section in South Fork

(Upper continuation of the section given under the Ordovician)

Pennsylvanian (Weber quartzite) :

Feet

en) SULO WAIST, BATICGSUONC ss isc sc k ec cle bis bce eee cee ened evees 500

MI LOMC I COMCIOMOCLA TEL. 5.0 6 cb ses bce ee ee een tacciceeseeane 3 to 10

Unconformity.

Mississippian (Reade formation) :

28. Cherty light yellow argillaceous limestone with large Zaphren-

MU CNN Fd we Ae rea eis is oo, oy ee, Soin GHA oS IC Saha MOS. RW Bi when aio D

27. Thin-bedded fossiliferous blue limestone...................... 350

Pree EM EROS AINE, PEC SUNG eh cree chic 2 tielele ah oleic uhama’d 2s ar cde Sie d sUalere ovis 35

Bee resMacOlored SHNUSLONE 2 iiiciswinls Les) gale. alae wielele nee baeldie wees 250

Pa wrassive blue, limestone. with productus. .......6 02... 06.00. .0 ed. 300

Devonian (Benson limestone) :

fa aare dark blue cherty coralline limestone..............0..6.e.. 100

PeOmiwe dark DIME MMESEONE . 6.166 6s in ec ee ses e cee ec ee ce 300

par Possiliterous, blue. limestone. oi... 6... tac ce te ewes Mate as 3

eeaeimek-peuged Dlie: HMeStONCG.< cc. 6. clk ks vce ec we awa ccesee cee 100

i. Dark blue cherty and brecciated limestone. ................6-.- 200

ead PED INE) MUTATOR EINE cS cco Gils oho ko auchen gw wise ete bial eve Gosek cle eotisiete lew eve abe 100

fe Dark porous Jdimestone, very fossiliferous ......0:.6.0.55 6. ce ee ec eee 21

16. Thick-bedded blue limestone, extensively bored................. , 120

fa nek -peaged. Hont Dine TiImeEStOne,. 2... 5 6. s5 ek as ce ec ele cee eee 43

fee kite -pemien, DTG THINGStONG.. ccs. ds sict cs be ees we ee cece owes 45

BIN SS Siac) jo BES DR a SOLS NOT hg en ee ere A ee 2,475

Disconformity.

Subformation: Mazfield formation.

Kindle?® has described the Jefferson limestone fauna and traced the

beds from their type locality in Montana southward into the Wasatch

Mountains of northern Utah. The following section is given from Green

Canyon :?"

19 J. M. BOUTWELL: U. S. Geol. Surv. Prof. Paper 77.

20K. M. KINDLE: “The Fauna and Stratigraphy of the Jefferson Limestone in the

Northern Rocky Mountains,” Bull. Am. Pal., Vol. 4, No. 20.

21 Toid., p. 16.

110 ANNALS NEW YORK ACADEMY OF SCIENCES

Section in Green Canyon

D. Gray non-magnesian limestone, partly covered.................... ee

©. Dark gray to black magnesian limestone, generally with saccha-

TOIGAL TEXTUTOS 5c.. 6g aiesdiaeie axe oinie a koro Sone petaas ee ete oheake nuaelatenegs © omnes 1,1002-

B. Thin-bedded limestone, buff or brownish near the top, with peculiar

conecretionary development with thin-bedded bluish-gray lime-

Stone ‘Tas lower allt. \. «ax. averse wie eisteese eheterel sche ene <eene aeeananen se eae en 100

A. White to light gray magnesian limestone, with chert or siliceous

beds locally. developed}. 2% 4..2c oe: se ety eee eee a ena 150

TOTAL sas bos Se wk Keke ew ce Sas LL ee ee 2250

Kindle correlates the dark magnesian limestone (C) with the Jeffer-

son limestone of Montana. The following is a list of the species ob-

tained from Green Canyon:

Productella spinulicosta

Camarotechia sp.

Spirifer argentarius

Leiorhynchus utahensis sp. nov.

Spirifer disjunctus var. animasensis

Pterinopecten sp.

Actinopteria sp.

Cytherella sp.

In discussing the evidence of the fauna of the Jefferson limestone,

Kindle has chosen three forms, Spirifer wtahensis, S. engelmanni and

Martinia maia, as the most abundant species represented, all of which

are not reported from the northern Wasatch section. All of these, how-

ever, and seven other types common to the Jefferson are characteristic

fossils of the Nevada limestone of Eureka, Nevada, with which Les

correlated.

The Jefferson limestone has a known north-south extent of 425 miles,

and from the thickness given for it in the northern Wasatch, it should

be expected to continue southward a considerable distance. Aside from

strata of close lithologic resemblance with the Jefferson reported by

Blackwelder from the region northeast of Ogden, nothing is known of

these beds south of Cache Valley. Eastward, they are not known beyond

a line through central Montana and western Wyoming. From northern

Colorado south to the southern part of New Mexico, the Ouray type of

Devonian prevails, characterized by Camarotechia endlichi and other

Upper Devonian types. The east-west line which separates these two

faunas appears to be the borderline between Colorado and Wyoming,

latitude 41° N. Extended westward, this line intersects the Wasatch

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH x Po bs |

about midway between Ogden and Salt Lake City and includes the

Eureka district of Nevada in the southern division. Since, however, the

Nevada limestone fauna shows close affinity with the Jefferson rather

than the Ouray, the line which separates the latter from the Jefferson

and Nevada limestone faunas must curve to the south somewhere in

Utah. It should be expected that these two distinct faunas representing

different parts of the Devonian, the Jefferson, Lower and Middle, and the

Ouray, Upper, will overlap somewhat, but thus far no section has been

found where this condition is shown.

Ouray Type of Devonian in the Central Wasatch

It was with very great interest that the writer discovered Camaro-

techia endlichi and a number of other typical Devonian forms in the

Cottonwood region. On Montreal Hill, near the head of Mill D, South

Fork, in Big Cottonwood Canyon, occur very fossiliferous light blue lime-

stones, at the base of which the following forms were obtained:

Schuchertella chemungensis Hall

Orthoceras sp.

Spirifer orestes var. wasatchensis var. nov.

Spirifer sp.

Fenestella sp.

Rhynchonella sp.

Immediately overlying this horizon and ranging through about 250

feet of limestones occur the following forms:

Euomphalus utahensis Hall and Whitfield

EF. luxus White

E. ophirensis H. and W.

Spirifer orestes var. wasatchensis

In a third richly fossiliferous horizon, in which Spirifer orestes var.

wasatchensis and Eunella linkleni are the most abundant, practically

making up the body of the limestone, occur the following:

Spirifer orestes var. wasatchensis

Hunella linkleni Hall

Cystodyctia gilberti Meek

Euomphalus ef. cyclostomus

Athyris coloradensis Girty, cf. A. brittsi Miller

Aviculopecten sp.

Camarotechia sp.

Cryptonella ? circulata Walcott

Euomphalus ophirensis H. and W.

11> ANNALS NEW YORK ACADEMY OF SCIENCES

In an outcrop considerably higher up, stratigraphically, but almost

completely covered so that it was somewhat doubtfully in place, two

specimens of the following well-known Ouray limestone type were ob-

tained:

Camarotechia endlichi Meek

Of the above species, the ones having the widest range are Huomphalus

and Spirifer orestes var. wasatchensis. Huomphalus utahensis, 2. lavus

and #. ophirensis have commonly been described as Mississippian from

their resemblance to the Waverlyan species of the Mississippi Valley.

Their association here with a Devonian fauna, and their range practically

from the bottom to the top, indicates that they are probably older than

Mississippian, though they may have persisted in other sections into the

lower part of the Mississippian. It would otherwise be necessary to

assume that the Devonian forms had survived till the Mississippian in

order to explain this association, but this seems hardly warranted from

the occurrence of Hunella linkleni Hall and Cystodyctia gilberti Meek

which are described elsewhere as coming from the Middle Devonian

(Lower Hamilton of Ohio).

In looking for the equivalent of this fauna in the West, that of the

Ouray limestone in western Colorado suggests itself both from its prox-

imity and its striking faunal resemblance. Kindle,?? who has described

the Ouray fauna and has done more than anyone else in suggesting a

correlation of the western Devonian strata, has the following to say:

“Camarotechia endlichi may be considered the most characteristic species of

the Ouray fauna, for it has been found at practically every outcrop where the

fauna has been recognized from northern Colorado to southern New Mexico.”

The occurrence of this widespread species in the central Wasatch has

brought the western border line of the Ouray fauna nearly 200 miles

west of the western boundary of Colorado, which Kindle believed to mark

its western limit. While the outcrop from which the Wasatch repre-

sentatives were obtained was poorly exposed and their associates were

not discovered, they may nevertheless be present in the Wasatch region,

and later search should reveal them. The presence, however, of this

most characteristic species is, it would seem, sufficient to indicate the

equivalency of the two formations. Moreover, the resemblance of the

faunas that were found below the endlichi horizon to the Upper Devonian

fauna of Iowa points to an eastern connection rather than one with the

Jefferson limestone of the West.

2H). M. KINDLE: Bull. Am. Pal., Vol. 4, No. 20, p. 20. 1908.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH i a

The stratigraphic relations of these beds to the ‘underlying non-fos-

siliferous limestones provisionally assigned to the Ordovician is one of

disconformity. The beginning of Devonian sedimentation is very clearly

marked by a limestone conglomerate which rests upon a thin bed of

yellowish-green shale, which in turn rests on a thick limestone member.

This condition is best shown on the Reade and Benson ridge, just above

the old mine workings of the same name. It is also exposed on the ridge

between Day’s Fork and Little Cottonwood Canyon, just west of Flag-

staff Mountain. No angular discord between the beds above and below

the break could be detected, though the presence of the hiatus is phys-

ically indicated by the unmistakable conglomerate.

Upward, the Devonian strata seem to be continuous with the succeeding

Waverlyan limestones. In this respect again, the central Wasatch is like

the Colorado and New Mexico areas where deposition is thought to have

proceeded continuously from the Upper Devonian into the Mississippian.

From the occurrence of these limestone beds on the Reade and Benson

ridge, the name Benson limestone is proposed to designate the part be-

longing to the Devonian. They range as above stated from Middle to

Upper Devonian and are succeeded by Lower Mississippian limestones —

without any observed disconformity.

MISSISSIPPIAN STRATA

Rocks of Carboniferous age have been known from the Wasatch Moun-

tains and the Great Basin region since the first explorations of Captain

Stansbury in the early fifties. It was left, however, to the Fortieth

Parallel geologists to give them a name and describe their stratigraphic

relations, thickness and distribution. King applied the name Wasatch

limestone to a succession of strata 7000 feet thick and composed mostly

of limestones supposed to be of “sub-Carboniferous” age. Aside from

the fact that this name was preoccupied for a Tertiary formation, it is

now known that the original Wasatch consists of several stratigraphic

members, ranging in age from Ordovician to Mississippian. In the

northern Wasatch, the Paradise limestone of Silurian age and nearly a

thousand feet of limestone identified by Kindle as the equivalent of the

Jefferson have been separated from the lower part of the Wasatch. The

rest has been regarded by Girty as Lower and Middle Mississippian, the

lower division probably correlating with the Madison limestone. It

seems advisable, therefore, to discontinue the use of the name Wasatch

limestone as employed by King.

In the central Wasatch region, the Mississippian strata admit of a

three-fold subdivision into a lower limestone series with a Productus

114 ANNALS NEW YORK ACADEMY OF SCIENCES

fauna, a middle sandstone and shale, apparently barren of fossils, and an

upper limestone series which is very fossiliferous. These beds are well

exposed in Big Cottonwood Canyon at the northern end of the Reade and

Benson ridge which separates South Fork from Day’s Fork. At Green’s

Hill in South Fork, the lower limestone can be traced across the canyon

from east to west. From the cliff which rises on the west, the following

forms were obtained :

Productus semireticulatus

Productus cora

Derby@ sp.

Hapsyphyllum sp.

The sandstone and shale which overhe this limestone member were

not well exposed within the district, usually forming the bottom of

gulches because of their poorer resisting qualities to weathering and

being largely covered with talus and soil. No fossils were found in them,

but they may have been overlooked because of poor exposures. The

sandstone, where seen, is composed of much angular material giving it

the aspect of a breccia. The prevailing color of the sandstone is light

yellow, straw color, while the shale which overlies it has a reddish tint.

It is an interesting fact that Blackwelder has noted a similar occurrence

sixty miles to the north, in Ogden Canyon, and several localities there-

abouts. The exposures there are apparently better and have been care-

fully described. Lavender and maroon shales with abundant sun-cracks

filled with mud and sand and the same brecciated appearance are noted.

From these and other characters, a continental origin is suggested, the

necessary conditions being found on the surface of deltas of flat gradient

in regions which are either generally or seasonably arid. The presence

of this non-marine member within the Mississippian was not noted until

it was discovered in Ogden Canyon by Blackwelder?* in 1910, and its

recognition in Big Cottonwood Canyon by the writer gives it a much

wider distribution and importance as a stratigraphic unit. It will, no

doubt, partly account for the limited development of the Mississippian

rocks in the Wasatch Mountains. In this connection, the unconformity

at the top of the over-lying thin-bedded limestones is of great importance.

As will be shown, this represents a great interval of time during which

much of the Upper Mississippian must have been removed by erosion.

From the fossiliferous portion of the limestone immediately below this

break, the following forms were obtained :

23. BLACKWELDER: “New Light on the Geology of Wasatch Mountains, Utah,” Bull.

G. S. A., Vol. 21, pp. 528-529, 1910,

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 115

Caninea cylindrica Scouler

Spirifer striatiformis Meek

Dielasma attenuatum Martin

Seminula subtilita

Spirifer rockymontanus

Productus semireticulatus

Phyllipsia cf. trinucleata Herrick

Amplexus sp.

Orbiculoidea newberryi

Spirifer sp. nov.

Caninea cylindrica is a well-known European species and so far as the

writer is aware has not been recognized before in America. It is char-

acteristic of the middle part of the Lower Carboniferous in Belgium and

the region about Bristol, England. Probably next in importance is

Spirifer striatiformis which is very abundant in the Cottonwood region.

It likewise points to the Middle Mississippian.

By far, the most abundant form is the great coral Caninea. The in-

dividuals lie closely packed together in a layer about three feet thick,

being very firmly cemented together with a siliceous clay which has be-

come exceedingly hard. They were discovered by the writer in the early

part of the season, and it was thought that they would make an easily

recognizable reference horizon on account of their abundance and size,

but while their general position was located in many places, no other

occurrence was found.

Immediately overlying this coral bed is the basal Pennsylvanian con-

glomerate made up of rounded chert pebbles and silicified corals together

with much fine material. This erosion surface truncates the lower beds,

as may be inferred by the absence of the coral layer in all other places

within the district except the one in which these interesting forms were

first discovered near the. mouth of South Fork. Careful observation

seems to indicate some difference of dip between the upper quartzite

beds and the lower limestones. The relation, therefore, is one of low

angular unconformity.

Unconformity between the Mississippian and Pennsylvanian

There can be no doubt that there exists an unconformity at the top

of the Mississippian in the Cottonwood section. The occurrence of a

similar break farther to the north has also been reported by Blackwelder?‘

at the base of the Morgan formation. He says: “The lower limit of the

formation (Morgan) is sharp, for the earthy red sandstones rest upon

% Op. cit.. pp. 529-530.

116 ANNALS NEW YORK ACADEMY OF SCIENCES

a cavernous weathered surface of fossiliferous gray limestone. Just

above the contact lies a coarse sandstone which consists of well-rounded

frosted sand-grains bound in a deep red matrix and including bits of

limestone and black chert from the underlying series. Although the

bedding of the Morgan formation is essentially parallel to that of the

limestone below, the relations here clearly indicate a disconformity, sig-

nifying an erosion epoch between the Mississippian and the Pennsylva-

nian.” From faunas obtained above the disconformity, which show close

relationships, the erosion interval is thought to be geologically brief in

that region. |

Dr. C. P. Berkey”® has also described an unconformity at the base of

the Weber quartzite in the western Uintas. He says in part:

“The base of the overlying formation, chiefly quartzite, is a true basal

conglomerate. There are abundant fragments and pebbles and boulders from

the cherty limestone bed immediately below, and in some places the finer

cementing or filling matter is calcareous rock flour (calcilutite) and granular

limestone (calearenite) and chert (silicarenite). Fossils are abundant below

the break but rare above it in this area. From the above, it is certain that

there is an erosion disconformity in the Upper Carboniferous of the Uintas

that marks moderate readjustment of levels, so that the strata are not perfectly

conformable in angle, although the later folding of the range has been so much

more profound that this is lost sight of except along the immediate break.”

In the western Uintas, there are two strongly developed quartzites.

Barring discrepancies in thickness and noting only succession, the upper-

most one of these would appear to correspond to the true “Weber.” ‘The

erosion break occurs here at its base. While Berkey puts the discon-

formity into the Upper Carboniferous, he establishes the fact that it

occurs below the Weber quartzite, which corresponds exactly with its

position in the Big Cottonwood section. Many of the details of descrip-

tion also correspond, such as the prevalence of cherty pebbles and much

fine material and slight discordance of dip between the upper and lower

layers. An absence of fossils above the break in these two sections is

also significant. In the northern Wasatch sections at the base of the

Morgan formation, fossils occur in limestone layers, showing, according

to Dr. Girty, that the unconformity there corresponds to a brief time

interval. 'T’o decide the value of the unconformity, 1t is only necessary to

find a section not too remote which shows no break and compare it with

the Wasatch sections and Berkey’s western Uinta section. Such a one

is to be had at Mercur in the Oquirrh Mountains.

“Al Oya Ed BERKEY : “Stratigraphy of the Uinta Mountains, Utah,”’ Bull. G. S. A., Vol. 16,

pp. 524-527. 1905.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 117

Mercur Section

In Lewiston Canyon, at the head of which is the little mining town

of Mercur, there is exposed a great anticlinal fold, the axis of which runs

northwest and southeast, somewhat diagonal to the general trend of the

range, which is north-south. Lewiston Canyon cuts directly across the

fold, exposing the anticline on both sides of the canyon. ‘The lowest

rocks brought up are of Lower Carboniferous age, and the highest ex-

posed, directly over the axis of the fold, are also of that age. The crest

of the range to the east rises on the east limb or flank of this anticline,

and here are exposed the rocks of Upper Carboniferous age. The section

thus exposed is as follows:

leet

Pataer anhercalated S@TICS. ..5.0.0......0s cee eee scecescceaeses D,000-6,000

Rae RTT PITMESTONG 20s sicsays she os omic le He bie wisls'acn wltewaseeswadsicanleed 5,000

eT Me rcalated: SETICS: . ..)00 6 2 ches ce bee coe skew see es ele see eles 600

Sere TPT FIFE UOTE. fr5, 2 cicceds ea. ksd'e overs she suas ajo Ba bee G6 bw es elaine ce 200

Above the Upper Intercalated series comes the great Weber quartzite

8000 feet thick exposed on the eastern slopes of the Oquirrhs at Bingham

and northward. Below the Lower Blue limestone, in Dry Canyon, which

parallels Lewiston Canyon on the north, are several hundred feet of

Lower Carboniferous limestone, below which come 2000 feet of Devonian,

Silurian, Ordovician and Cambrian strata. There is thus a great series

of sediment exposed in these three localities ranging from the Cambrian

to the Upper Carboniferous.

Fossils obtained from the Lower Blue limestone by Mr. Spurr,”® and

examined by Professor Schuchert, were found to be of Mississippian age.

The limestone is a dark blue, semi-crystalline rock, in which zaphrentoid

corals seem to be the most abundant fossils.

Above the Lower Blue comes the Lower Intercalated series, 600 feet

thick, the lowest member of which is a sandstone 100 feet thick. Above

this come frequent alternations of siliceous and calcareous sediments

(silicilutytes and calcarenytes). T'wo paralle] sections measured on the

steep bare walls of the canyon three-fourths of a mile apart showed con-

siderable thinning of these beds toward the east, even in this slight

distance.

Above these intercalated beds is a great limestone succession 5000 feet

thick, broken only in two places by very dark calcareous shales, one about

a thousand feet below the top and the other about the same distance from

2% J. E. Spurr: “Geology of Mercur District, Utah,’’ U. S. Geol. Surv., 16th Ann. Rept.,

Part tl, pp. 3ti-3tT. 1894.

118 ANNALS NEW: YORK ACADEMY OF SCIENCES

the bottom. From the lower shale, a bryozoan and brachiopod fauna was

obtained, which Professor Schuchert assigned to the Burlington-Keokuk

horizon, The upper limit of the Great Blue limestone merges gradually

into the Upper Intercalated series, which, with its frequent alternations

of siliceous and calcareous beds, is In sharp contrast with the heavy blue

layers of the Great Blue limestone. Between these two formations,

Schuchert places the division between the Carboniferous and Mississip-

pian. The Mississippian in the Oquirrhs is thus made somewhat over

6000 feet, and the upper division, counting the Weber quartzite exposed

at Bingham and over a large area to the north, between 15,000 and

18,000 feet.

To facilitate the discussion and bring out the relationships which exist

among the Carboniferous formations of the Oquirrh, Wasatch and Uinta

mountains, columnar sections from these three ranges taken in an ap-

proximate east-west line through the Cottonwood district have been

drawn side by side in Fig. 4. The distance between Mercur and Big

Cottonwood Canyon is about equal to the distance from Big Cottonwood

to the western Uintas, being in the neighborhood of thirty-five miles.

The much greater development of Mississippian and Pennsylvania

strata in the Oquirrh Mountains is seen at a glance. The corresponding

parts are indicated by the dotted lines. It becomes apparent at once that

the unconformities shown in the Wasatch and Uinta sections represent a

long interval of erosion. Farther to the east, in Colorado, this same

unconformity has been reported between the Mississippian and Pennsyl-

vanian formations, and the same explanation no doubt applies there as

well. It seems reasonable to suppose that the Mississippian was repre-

sented by much thicker formations in these sections at the beginning of

Pennsylvanian time than is shown at present. The Great Blue limestone

was very probably represented in them all, but just when the area of the

Wasatch and eastward into Colorado was lifted and exposed to erosion —

cannot be definitely stated. It was probably toward the end of Great

Blue time. During the long period of erosion which followed, most of

the Mississippian limestone was worn away and transported elsewhere to

be deposited as calcareous mud or, if dissolved, remain in solution in the

sea water. The new shore line receded westward until it came to occupy

some position between the Wasatch and Oquirrh mountains. Here it

seems to have remained for a long time, as we may judge from the nature

of the great deposits which formed in the Oquirrh Mountain area.

Above the Great Blue limestone, we have the Upper Intercalated series,

which on the Mercur side of the divide is from 5000 to 6000 feet thick,

but it continues east of the divide and may be as much as 10,000 feet in

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thickness before the Weber quartzite is reached. This series is described

as consisting of numerous alternations of sandstones and sandy limestones.

many of the beds presenting for considerable distances complete inter-

mediate stages between the more calcareous on the one hand and the

more arenaceous on the other. ‘The presence of marine fossils through-

out the series, in the more calcareous layers, may be taken as good proof

that the deposit was formed in the sea and probably not far from the

shore. The lime muds from the great limestone area toward the east

became mingled with the sands of the shore, giving rise to the calcareous

sandstones which are so prominent a part of these intercalated beds.

The Mercur report leaves much to be desired in the matter of details

concerning the organic record. With the excellent exposures to be had

there and the obvious importance of knowing what fossils are imbedded

in these rocks, it is to be hoped that this section will soon receive the

careful study which it deserves. Enough has been done, however, to de-

termine the age of the series as a whole, and to warrant the comparison

that is here made. Following Spurr’s report, we may assume that depo-

sition was continuous in the Oquirrh Mountains. The hiatus, therefore,

in the Wasatch and Uinta sections, represents a long erosion interval,

comparable in time to the period necessary for the deposition of the 6,000

to 10,000 feet of intercalated limestones and sandstones. It seems also

probable that it was even much longer, as will be brought out in the dis-

cussion of the Weber quartzite problem (see Fig. 4).

PENNSYLVANIAN STRATA

Weber Quartzite

Following the basal Pennsylvanian conglomerate in the Big Cotton-

wood section is a quartzite 1000 feet thick, in which no fossils were

found. The sand grains are of fairly uniform size, giving a rock of

even, rather fine-grained texture. The bedding is prominent and regular

-in layers of moderate thickness, While the surface has a brownish ap-

pearance, the freshly broken rock is quite colorless. Ripple marks, cross-

bedding and other shallow water characters seem singularly wanting, yet

the fine detrital nature of the deposit certainly points to shallow water

deposition. In the upper portion, thin limestone layers are intercalated

between the sandy beds, and a succession of mainly cherty blue and white

limestones follow, making up several hundred feet in thickness. These

are well exposed on the north side of the canyon, just opposite the gov-

ernment forest station. Above these limestone beds, the quartzites reap-

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 131

pear and give another thousand feet of fine-grained white rock. The

series thus defined above the disconformity which terminates the Missis-

sippian strata constitutes what is here called Weber quartzite. In the

Park City district to the east, Boutwell?* reports only the upper portion

of the Weber quartzite as seen in outcrops.

“The middle and basal portions of the formation, which are not present in

this area, outcrop in prominent cliffs just south of the district. Except for a

few thin limestone beds near its top, the middle portion is massive quartzite,

but in the lower part, the intercalated limestone members increase in number

and thickness.”

The middle and basal portions here mentioned correspond with part of

the upper and middle parts of what is called Weber quartzite in this

report. The thickness given in Boutwell’s section is 1350 feet, which he

regards as too small and gives a tentative estimate of 3500 feet. The

exact thickness is still doubtful, as continuous exposures could not be

found within the Cottonwood district, but 3500 feet is probably too great.

Somewhat more than 2000 feet is thought to be more nearly correct.

In the type locality in Weber Canyon, 30 miles to the north, the For-

tieth Parallel geologists?* have given the thickness as 5000 to 6000 feet.

This figure has been questioned by Blackwelder,?® who follows Weeks*®

and separates the lower red beds of that section from the Weber and calls

them the Morgan formation. There is, however, no doubt that the de-

velopment of the Weber quartzite in Weber Canyon is considerably

greater than in Big Cottonwood and that the thickness is subject to

variation from place to place. In less than 15 miles north of Weber

Canyon, it disappears altogether and the Park City limestone which

overlies the Weber in all of the southern sections rests directly on Mis-

sissippian limestone. Blackwelder describes the unconformity as one of

low angular discordance, the beds of early Mississippian age being slowly

truncated, over the edges of which the Park City limestone rests. As we

go southward, the Morgan formation and Weber quartzite appear be-

tween the Mississippian limestone and Park City formation. The Park

City beds thus overlap the Weber quartzite and Morgan red beds, and

going still lower rest on early Mississippian.

It is also important to note that in Weber Canyon, the Morgan forma-

tion rests on much higher Mississippian beds than in the northern sec-

tions. This fact may be explained in several ways. The presence of a

27 J. M. BOUTWELL: U. S. Geol. Surv. Prof. Paper 77, p. 45.

*C. KinG: U. S. Geol. Expl. 40th Par., Vol. I, p. 161.

2H. BLACKWELDER: Op. cit., p. 531.

°F. B. WEEKS: Unpublished report of U. S. Geol. Sury., quoted by Blackwelder. 1908.

129 ANNALS NEW YORK ACADEMY OF SCIENCES

widespread unconformity between the Pennsylvanian and Mississippian

throughout Colorado, Wyoming, northern Arizona and all of Utah, with

variable amounts of the Mississippian strata present in the different sec-

tions, may explain the absence of the Upper Mississippian strata in

Blackwelder’s northern sections. That this was a long period of erosion

has already been explained, and the disappearance of the Weber north-

ward may well be by natural thinning due to overlap. The position of

the Weber quartzite in the Oquirrh Mountains above the intercalated

beds, which are not represented in the Wasatch sections and those farther

to the east, indicates that the hiatus at the base of the Morgan formation

in Weber Canyon represents a considerable interval of time. The Mor-

gan formation is considered to be of very local extent and may be taken

to be a part of the Weber.

The relation of the Weber to the overlying Park City formation is de-

scribed in the early reports as one of complete conformity. In the Big

Cottonwood section, the division line is covered in most places and was

not studied in detail by the writer. The section given by Boutwell** in

the report on the Park City district, as the type section for that area,

was measured in Big Cottonwood Canyon, on the ridge east of Mule

Hollow. This section was verified by the writer and may be taken as

representative for the upper divisions of the Weber quartzite and higher

formations. Of the contact in question, the Park City report reads as

follows:

“No unconformity was observed with the underlying Weber quartzite, or the

overlying shale, or within the formation (Park City). Accordingly, it would

seem that sedimentation proceeded unbroken from Mississippian time through

that part of Pennsylvanian which is represented by the Park City formation.”

Blackwelder®? on the other hand concludes from his studies in Weber

Canyon that there is an unconformity. He says:

“The Weber quartzite is limited above by an irregular eroded surface, which

is not exactly parallel to the bedding; it was subject to disintegration ; and not

merely one, but a variety of beds in the formation were exposed, as is shown

by the large amount of chert as well as quartzite in the breccia. On the whole,

the evidence for the existence of an unconformity at this horizon seems to be

conclusive.

“The importance of the unconformity is uncertain. If the Weber quartzite is

a formation of only local extent, and if some of the more calcareous beds

farther north were deposited contemporaneously, then the observed uncon-

formity may in fact be due to a slight erosion of the surface of the formation

2 Op. cit., p. 51.

32 Op. cit., p. 533.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 123

and should represent but a brief land interval. If, however, the Weber quart-

zite was once far more extensive than now, and if it has been removed from

the northern part of the Wasatch region, and elsewhere reduced to a varying

thickness by erosion within the Pennsylvanian period, then the interval must

have been relatively long. It is significant in this connection, that the frag-

ments of quartzite in the basal breccia were quartzite, rather than sandstone,

when broken from the parent ledge, during the erosion interval, as is shown

by the preservation of sharp corners and edges.”

The exact amount of time represented, if we grant the presence of an

unconformity between the Weber quartzite and the Park City formation,

can only be decided by finding out the ages of these two members. If the

Park City formation is Pennsylvanian in age and the Weber quartzite is

late Pennsylvanian, as the Oquirrh mountain sections indicate, then the

interval must be short and relatively unimportant and cannot explain the

great variation in thickness of the Weber and its total disappearance in

sections not far distant from its type locality. If, on the other hand, the

Park City formation is made Permian in age and the Weber quartzite

early Pennsylvanian, then a great hiatus must exist between the two for-

mations. Such a one should be well marked, and we should expect it to

be especially easy to recognize where the Weber is thinnest by its most

extensive erosion. The presence of a basal conglomerate with well-

rounded quartzite pebbles should be expected within short distances of

the present occurrences of the parent body. Again, if the Park City,

formation is Permian in age and the Weber late Pennsylvanian, a small

hiatus may exist between the two, such as has been described by Black-

welder. It may be safely assumed that the Park City beds are late Penn-

sylvanian or early Permian, and in view of the high position of the Weber

quartzite in the Oquirrh mountain sections, it seems clear that no great

erosion interval exists between these two formations. The thinning of

the Weber is more easily accounted for by overlap, as it was undoubtedly

laid down on a surface that had been long exposed to erosion.

PARK CITY AND LATER FORMATIONS

The Park City formation has been named from the Park City mining

district within which it carries bonanza ore bodies. No good exposures

are known, however, from the Park City area; and within the area

specially studied for this report, the formation does not occur. It is of

interest, nevertheless, to give the characters of this formation some con-

sideration from the widespread occurrence of this member in the central

Wasatch and northward.

124 ANNALS NEW YORK ACADEMY OF SCIENCES

The Park City formation hes between the Weber quartzite and the

red beds of the Woodside shale, and, in the type locality on the north

side of Big Cottonwood Canyon, it has a thickness of about 600 feet.

As exposed there, it consists largely of limestone with intercalations of

sandstone and quartzite. Its differentiation below from the Weber quartz-

ite is readily made by the appearance of calcareous layers which soon give

way to a thick bed of limestone. As before stated, in the central Wa-

satch this transition indicates continuous deposition from Weber into

Park City time. The occurrence of limestones nearly as extensive as

those of the Park City formation within the typical Weber is well known,

and this suggests that the Park City beds mark the recurrence of one

of these periods of limestone formation when typical marine conditions

prevailed.

In the older reports, the upper coal measure limestones represent this

horizon. They were especially noted for the abundant fauna which they

carry and have usually been regarded as of Carboniferous age. Of late,

however, some tendency is shown to place them higher in the series,

possibly in the Permian. In the correlation table here given, the inter-

pretation of the various workers is placed at the right and that of the

writer on the left. This view is supported by the fauna and stratigraphic

relations which are better shown in Dry Canyon, to the north, than in

Big Cottonwood Canyon. There is in that section between 500 and 600

feet of red shales and brownish sandstones between the Meekoceras beds

of the Lower Triassic and the upper fossiliferous portion of the Park

City formation. These seem to rest with low angular unconformity upon

the Park City beds and carry an abundance of a single species of Lingula

in the beds next to the contact. Faulting is frequent in this area, and

the apparent discrepancy in dip between the two sets of beds may be due

to that cause, but a search failed to reveal evidence of faulting. From

the nature of the beds of red shale and brownish sandstones, it might be

expected that they should bear a relation of unconformity, or at least

disconformity, to the typical marine beds upon which they rest. From

the widespread occurrence of Permian red beds in the west, these are

thought to be of that age. The fauna of the upper part of the Park

City formation indicates their Carboniferous age. Prominent forms are:

Productus multistriatus

Productus subcostatus

Spiriferina pulchra

Spirifer cameratus

Lingaulodiscina utahensis

Athyris (Seminula) argentea

(Rhynchonella) Pugnar swallowiana

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 125

In Red Butte Canyon, the next gulch to the south of Dry Canyon,

occurs a heavy conglomerate and a considerable, thickness of purple

sandstone. These purple beds were called Permian by the geologists of

the Fortieth Parallel Survey. Overlying them are the strongly cross-

bedded red sandstones which form the prominent red cliff at the mouth

of the canyon, from which it has derived its name. These are the

“Triassic red beds” of Hague and Emmons. The discovery of the

Meekoceras fauna several hundred feet below the purple sandstones has

carried the lower limit of the Triassic down below what was called Per-

mian into those beds which were mapped as upper coal measures by the

Fortieth Parallel geologists. The simple synclinal structure for this

region shown on the Great Basin sheet of that survey is now also known

to be more complicated, including at least one large anticline and an-

other syncline to the south of Emigration Canyon. The new geologic

map of this region now being prepared by Mr. N. C. Christensen and

Dr. F. J. Pack will look very different from the present one, and it is

expected that the separation of the Jurassic, Triassic, Permian and Car-

boniferous can be definitely accomplished in this region. For the pres-

ent, the interpretation here given (page 126) is thought to be very near

the true one. |

MY OF SCIENCES

ANNALS NEW YORK ACADE

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HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 19/7

STRUCTURE

INTRODUCTORY STATEMENT

The first unified account of the larger structural features of the

Wasatch Mountains is that given by the geologists of the Fortieth Paral-

lel Survey.** In a broad way, these early observations have been verified

by the more recent studies of particular parts of the range, but many

important new facts have been added and some of the original concep-

tions greatly changed.

Vital to the first conception of Wasatch structure was the supposed

presence of an Archean axis which had the same trend as the present

range, north and south, on the flanks of which were deposited the early

Paleozoic sediments, until they completely buried the lofty Archean

peaks. At the close of Mesozoic time, profound plicating and plateau

forming movements threw the thick conformable Paleozoic and Mesozoic

sediments into great pitching anticlinal and synclinal folds with axes

mainly north and south. After a period of erosion during which the

upper parts of the folds were planed off, profound faulting along the

present western faces of the range took place, tilting the old surface

eastward on the uplifted eastern side. Upon that uplifted block, erosion

has carved the present relief.

It is now known that the main body of supposed Archean, the Little

Cottonwood granite, is intrusive, and the original conception of a pre-

Cambrian protaxis has been entirely discarded. Folding is known to be

much more intense than originally thought, and large overthrusts have

been discovered from Ogden northward to Willard and in the Cotton-

wood district.

Since the overthrusting, there has been considerable deformation and

faulting which have introduced the most complicated tectonic relation-

ships.

STRUCTURE OF THE CENTRAL WASATCH

The central Wasatch is an exception, structurally, from the general

anticlinal aspect of the range as a whole. Within this area, extensive

intrusion of granite and granodiorite and widespread extrusion of ande-

sitic lava, with their accompanying phenomena of metamorphism, are

grandly displayed. Encircling the main intrusive body, the Little Cot-

-tonwood granite, are steeply inclined quartzites, shales and limestones,

with varying age ranging from pre-Cambrian to late Mesozoic. ‘Dipping

3. S. Geol. Expl. 40th Par., Vol. II, Sect. 3 & 4.

128 ANNALS NEW YORK ACADEMY OF SCIENCES

quaquaversally from the nucleus of granite, this great series of sediments:

forms the eastern half of a huge dome abruptly cut off on the west by a

profound fault. The western half was depressed and is now entirely

covered by the deep accumulation of rock waste forming the floor of the

Salt Lake Valley. Eastward, the Carboniferous and Triassic formations

are breached by an irregular stock of fine-grained granodiorite which

culminates in Clayton Peak. Beyond this line of elevation, which forms

the present divide, an extensive flow of andesite was poured out in an

elongated synclinal depression that separates the Wasatch from the

western Uintas. It is significant that the anticlinal fold of the Uinta

range is in line with the eastward prolongation of this domed arch and

that they are connected beneath the igneous covering by the Kamas

prairie syncline.

Iittle Cottonwood Granite

The structural relation of the Little Cottonwood granite to the sedi-

ments which flank it upon all sides has been variously interpreted. By

the geologists of the Fortieth Parallel, the contact was described as one

of sedimentary unconformity; and the granite was thought to be older

than the quartzites that appear to overlap it. The absence of a basal

conglomerate was noted, and the whole situation was thought to be ex-

traordinary. At that time, the intrusive occurrence of granite had not

been conceived, and the indications of contact and regional metamorphism

escaped notice, so that while the evidence of a sedimentary contact was

not in accord with conditions commonly regarded as necessary, the rela-

tion was still held to be due to sedimentation.

In 1880, Geikie** visited this region and later published his conclu-

sions. He found structural evidence that led him to regard the granite

as intrusive, and probably post-Carboniferous in age, rather than pre-

Cambrian as given by the Fortieth Parallel geologists.

In 1900, Boutwell visited Little Cottonwood Canyon and examined

the contact of the granite and quartzite on the ridge south of Twin

Peaks. Here he found dikes of granite extending up into the quartzite

and sills of granite leading off laterally from the dikes. Inclusions of

quartzite in the granite were also observed, and the intrusive nature of

the granite was thus established. These results were verified by Em-

mons**® who later published his conclusions regarding the granite as in-

3% A. Gpikien: “Archean Rocks of Wasatch Mountains,’ Am. Jour. Sci., 3rd Ser., Vol.

19, pp. 363-367. 1880.

3S. F. Emmons: “Little Cottonwood Granite Body of the Wasatch Mountains,” Am.

Jour. Sci., 4th Ser., Vol. 16, pp. 1389-147. 1903.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 129

trusive and pre-Jurassic in age and the chief folding of the sediments

as Jurassic.

The Little Cottonwood granite has commonly been regarded as lac-

colithic in structure, since its intrusive character has been known. While

the inclosing quartzites do dip away in all directions from the central

igneous mass, suggesting that they may have been arched up by the in-

trusion, the essentials of laccolithic structure are nowhere shown. ‘The

far-reaching metamorphic effects of the granite upon the contiguous

sediments, its uneven ragged contact on all sides and its thorough crys-

talline coarse texture all indicate a mass of irregular shape and great

size. It would seem advisable, therefore, to speak of the Little Cotton-

wood mass as a stock and reserve the term laccolith for the more special

type of intrusive.

As to the geologic data of the intrusion, there is also much uncertainty.

The latest sediments cut are Algonkian, and possibly Lower Huronian,

in age. If the mass were known to be laccolithic, then the latest sedi-

ments affected by the arching would give the desired information; or,

if the doming of the strata is due to the intrusion of the granitic stock,

then the age might quite easily be stated as later than the youngest beds

that are involved. But it is difficult in this region of strong folding to

distinguish between the flexing due to regional folding and that due to

a special cause such as intrusion, where the two come so close together.

A few general considerations may lead to a closer approximation of

the date of the intrusion than can be made from the sediments cut by it.

The Little Cottonwood granite mass les in an east-west zone of eruption

which has been active in some parts in post-Triassic, probably Tertiary

time. At Bingham, it is marked by a large body of post-Carboniferous

monzonite and trachytic extrusion. Still farther west, the sheets and

dikes of the Mercur and Ophir districts are in the westward continuation

of this belt. Just east of Alta is a large irregular stock of granodiorite

which cuts Carboniferous limestones and adjoining it to the east is the

Clayton Peak mass of quartz diorite which cuts Triassic strata. The

interrelations of these three main intrusive bodies have not been discovy-

ered in the field. They are not in surface connection with each other, so

far as known, but a northeast-southwest system of dikes and veins is

characteristic of the whole region; and closely associated with the ore

bodies. These dikes are clearly later than the folding, since they do not

show deformation and from their similarity to the larger intrusive masses

they may be assumed to have come from them, though none has actually

been traced to the junction point. They are seen to disappear beneath

rock debris within a few hundred feet of the larger bodies, however, and

130 ANNALS NEW YORK ACADEMY OF SCIENCES

are surely connected with them. If such a contact could be seen, it would

shed much light upon the relative ages, but in the absence of actual

proof, we may only reason about them.

If we assume that the Little Cottonwood granite, the Alta granodiorite

and the Clayton Peak quartz diorite are connected below, as is commonly

done, they are probably not of very different ages and may be taken as

being as young as the most recent sediments cut. This would make them

post-Triassic. If the fracturing of the beds and intrusion of the dikes

came after the folding, which is thought to be late Cretaceous, and if this

occurred contemporaneously with the intrusion of the larger bodies, as

might be the case, then the Little Cottonwood granite, as well as most of

the other igneous masses, are post-Cretaceous.

The extrusive andesites of the Kamas prairie to the east are in contact

with the Vermillion Creek beds of the Eocene as reported by the Fortieth

Parallel geologists.*° They are thus later than these early Eocene beds

and represent the latest igneous activity of the region. Their relation to

the porphyritic dikes and granitoid intrusives of the Cottonwoods is not

known, but they are probably much later. The Little Cottonwood granite

was no doubt uncovered during the period of erosion which followed the

post-Cretaceous folding. The extrusions came after the upturned Paleo-

zoic and Mesozoic beds had been strongly truncated, covering the old

surface in the depression between the Wasatch and Uinta mountains,

The date of the intrusion of the granite will presently be further dis-

cussed when the problem of overthrusting and faulting near Alta is taken

up. From the above, it appears that the granite probably came in 1mme-

diately preceding or possibly accompanying the folding in post-Cretaceous

time. The eruptive andesites are post-Vermillion Creek and belong un-

doubtedly to the Tertiary period.

STRUCTURE NEAR ALTA

In the Alta region, the most obvious structure is an eastward dipping

monocline, which to the north and south slowly curves westward, in ac-

cordance with the general dome structure for this part of the range.

The strata stand at a considerable inclination, averaging between 35 and

45 degrees, but locally the dip may be much more and in some parts

notably less. This simple structure is much complicated in places by

folding and faulting. The folds are confined to a zone within the sedi-

mentary series, the formations above and below having the ordinary

monoclinal attitude. This condition has been brought about by over-

%*S. Ff. EMMONS: U. S. Geol. Expl. 40th Par., Vol. I, pp. 586-587. 1878.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 131

thrusting, the weaker members in the lower part of the overthrust mass

having been rolled together in such a way as to make it almost hopeless

to try to make out any regular structures. Small Z-shaped folds have

resulted in several places, and in others, overturned and isoclinal folding

may be observed. North and south of Alta where the disturbance seems

to have been the greatest, the weak shales of the Cambrian system have

been drawn out into long tongues in the midst of the quartzites, entirely

isolated from the limestones which normally overlie them. The dynamics

by which this was accomplished in a region so complicated can hardly be

explained. The strata plainly show that they have been torn loose from

their normal position in the sedimentary series and involved in the zone

of shearing so as to be widely separated from their former position.

In Big Cottonwood Canyon, above the Alta black shale exposed near

the old Maxfield mine, rises a great series of limestones. Below the shale

is a thickness of about 1200 to 1500 feet of Cambrian quartzite, and

below that the Algonkian quartzite slate series 11,000 feet thick forms the

base of the section. There is thus in Big Cottonwood Canyon a great

limestone series overlying the Alta shale. These may both be traced south-

east across the canyon where the limestones are seen to form the top of

Kessler’s Peak. Still farther along the strike, they cross South Fork and

are best seen as the chief rocks making up the Reade and Benson ridge,

on the east wall of South Fork. They may be continuously followed

south into Little Cottonwood Canyon where they form the ore-bearing

zone north of Alta. The Cambrian black shale can be traced along in

the same way and some of the underlying quartzite, but just below Alta a

second lower series of limestones outcrops in bold cliffs on both sides of

the canyon, facing Superior and Peruvian gulches. To one familiar with

the Big Cottonwood succession where no limestones appear below the

Cambrian rocks, this condition at once suggests an overthrust. An ex-

amination of the rocks below the lower limestone revealed the Cambrian

black shale as the first member and the familiar Lower Cambrian quartz-

ites and the upper part of the Algonkian quartzite and slate series as the

downward continuous succession. Below the upper limestones, which

were traced over from Big Cottonwood, are, in order going down, the

Cambrian black shale (Alta), the Lower Cambrian quartzite (Brigham)

and the upper part of the Algonkian series which rests upon the lower

limestones. There is thus a complete duplication of the strata from the

upper part of the Algonkian through the Cambrian and including the

lower 1000 feet of limestone of Ordovician and Devonian age. The evi-

dence for overthrusting is therefore conclusive from a stratigraphic view-

point. It seems strange that the Fortieth Parallel geologists should

132 ANNALS NEW YORK ACADEMY OF SCIENCES

have overlooked this relationship. They seem to have been prejudiced

from the similar relations which they had observed in the range to the

north, in Weber and Ogden Canyons. In describing the Big Cottonwood

section, King*’ has the following to say:

“Next above the Cambrian lie 1,000 feet of Ute limestone, which for the

most part is very light colored, highly crystalline and characterized by peculiar

cloudings of color that extend across the beds near the bottom of the series,

and at one or two horizons near the top it is noticeable for containing a

large proportion of tremolite, and under the microscope it is seen to be highly

siliceous, the silica appearing as rounded glass grains of pellucid quartz. The

outcrop extends up the hills on both sides of the canyon and to the south is

conspicuous upon the divide, from which it descends into Little Cottonwood

and in the valley a little way below .Alta exposes a fine precipitous cliff, the

result of a fault (the Superior fault of this report). Here again are seen the

same highly crystalline, almost marble-like condition and the same prevalence

of tremolite and silica. Under these circumstances it is not at all remarkable

that the beds contain no fossils, but it is unquestionably Silurian. as will be

seen later.

“Above the limestone occurs the white granular body of Ogden quartzite,

which is here reduced in thickness to about 800 feet. It may be traced up the

hill to the south and forms an interesting saddle in the ridge top, between the

Ute limestone and the bold masses of Wasatch limestone which directly overlie

it. Here are but limited traces of the thin body of greenish argillites that far-

ther south, in the region of Rock Creek, were found on both sides as bounding-

beds to the Ogden body.”

The presence of the “Ogden” quartzite between the “Ute” and “Wa-

satch” limestones in the Big Cottonwood section seems to have been

inferred from its prominent appearance on the ridge above Alta. In Big

Cottonwood Canyon, no such quartzite member is exposed. The outcrop

at the head of South Fork, having the described position between the two

limestone members, can be traced northward along the strike of the beds

into Big Cottonwood Canyon, where it appears below the lowest lime-

stones there exposed. It therefore clearly belongs to the Cambrian. This

fact might easily have been discovered had the early geologists attempted

to explain the presence of a black shale above the “Ogden” quartzite on

the ridge above Alta. For some reason this important horizon marker

was overlooked or disregarded altogether. The “limited traces” above

referred to are hard to harmonize with the good exposure of this Cam-

brian shale at the south end of the Reade and Benson ridge, where it

shows its typical thickness, between 150 and 200 feet. The lower occur-

rence, below the “Ute” limestone, seems to have been noted, though the

7 C, Kine: U. S. Geol. Expl. 40th Par., Vol. I, Sys. Geol., pp. 167-168. 1878.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 138

thickness and exposure there are hardly more favorable for observation.

The strong contrast between the black shale and the almost white quartzite

makes the presence of the shale easy to recognize and renders it one of the

best guides to the surface geology of the region (see Plate III, A).

Alta Overthrust

As already stated above, there is complete stratigraphic evidence of a

large overthrust in the vicinity of Alta, for which the name Alta over-

thrust is proposed. It has been traced north from the locality where it

was first discovered northwest of Alta into Big Cottonwood Canyon and

south into American Fork. There can be little doubt, however, that it

extends much farther in both directions. The dip of the overthrust beds

is not very different from that of the strata upon which they rest, so that

the attitude of the beds above the thrust surface furnished no clue to the

relationship. The strong contrast in color and lithologic characters be-

tween the various stratigraphic members soon led to the recognition of a

complete duplication of beds. The other factors were then soon discov-

ered. Evidence of intense dynamic action was found in the highly folded

and contorted conditions of the weaker strata. Rapid variation in the

thickness of the beds, and the complete disappearance of some of them

above and below the thrust surface were noted.

The accompanying diagram (Fig. 5) shows the relation of the beds

above and below the thrust surface as they occur between Alta and

Argenta, a distance of about four miles. The succession at the right is

the same as that seen in the photograph (Plate IV, A). As we go north-

west, the lower members of the series above the thrust line T T’, as well

as the limestones and shale below it, disappear, so that when Argenta is

reached these beds are missing. The Cambrian quartzite has apparently

become much thicker, being nearly twice as thick as it is in the two ex-

posures near Alta and at the head of South Fork. The only duplication

of strata shown in Big Cottonwood is the Cambrian quartzite, and that

shows itself in the increased thickness of the beds, the exact line of sepa-

ration not having been observed. On the north slopes of Kessler’s Peak

coming around from Mineral Fork, the thrust surface disappears beneath

a heavy mantle of débris, and where it emerges on the north slopes of

Big Cottonwood, it has not been found again.

From Alta southward, the thrust surface is more easily traced. The

lower limestones outcrop all along the east wall of Peruvian Gulch to

the Bullion Divide, where they cross over in a low saddle and form the

floor of the great cirque at the head of American Fork, known as Min-

134 ANNALS NEW YORK ACADEMY OF SCIENCES

eral Flat. The lowest overthrust member is quartzite, plainly seen as

the capping of Bald Mountain directly south of Alta (see geologic map,

Plate VI). All along Peruvian Gulch and in American Fork, this

seems to lie conformably upon the limestone. Both the limestone and

the quartzite being very resistant, the contact is often sharp with very

little crumpling or brecciation. ‘The truncation of the beds, however,

shows beyond any doubt the secondary nature of the structure. More-

Argenta Alta

FIG. 5. SECTION BETWEEN ARGENTA, IN BIG COTTONWOOD CANYON, AND ALTA, IN LITTLE

COTTONWOOD

Relation of the overthrust Paleozoic and Proterozoic strata to beds of the same ages

below

1 — Algonkian quartzite. 2— Algonkian ‘‘conglomerate.” 38=——=Cambrian quartzite

4—Cambrian shale. 5— Ordovician and Devonian limestones. TT’ — Thrust surface

over, in many places crumpling and brecciation have occurred—as should

be expected. In all such cases, the limestones have been the least af-

fected, but the overthrust quartzites and shales have suffered strong

deformation. The best example of this condition is seen on the slopes

northwest of Alta. The black Cambrian shale has here been drawn out

into a long tongue in the midst of the quartzite, showing every inclination

from strongly overturned folds near the Columbus mine to a vertical posi-

tion farther up the hill. The quartzite is folded and smashed in such a

way as to’ be chaotic, individual blocks being traceable for short distances

only.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 135

In the mine workings on this hill, the discontinuity of the beds seen

on the surface is also shown. No regular structure can be followed very

far within the quartzite, or overthrust zone. The deeper workings which

drift far to the westward finally enter the limestones below the thrust

mass, and here the dip is regular to the east. The thrust contact dips

strongly to the east on the surface, but deeper it gradually flattens out.

The age of the overthrust is not positively known, but there can be

little doubt that it occurred during, or at least at the close of one of the

periods of folding in late Mesozoic time. The folding of the Wasatch

is generally assigned to the close of the Cretaceous, but King** has de-

scribed an unconformable contact between the local Dakota beds and the

Jurassic and older sediments exposed along Mountain Dell road in the

upper part of Parley’s Canyon. The difference in dip of the beds is

given as about 30 degrees, and the Cretaceous strata rest on the truncated

edges of all of the older Mesozoic and Paleozoic formations, but else-

where the Cretaceous is described as conformable with the older series,

and this relation is the commonly accepted one. More work will have

to be done to settle this question. If there was important folding at the

close of the Jurassic, the overthrust in the Cottonwood region could have

occurred then. It certainly took place before the intrusive action oc-

curred in this district, as is evidenced by the independent manner in

which the dikes cut through the basal series and overthrust blocks. This

event followed or accompanied a period of northeast-southwest fracturing

and faulting which preceded the period of mineralization. Still later,

important faulting transverse to this first fracture line occurred, of which

the Superior fault is the best known example. The overthrusting, there-

fore, appears to have happened along with or following the first dynamic

disturbance in the region. Later warping has deformed the thrust sur-

face and tilted the masses at a high angle.

Farther north in the range, Blackwelder*®® has described similar struc-

tures which he thinks were made at the same time that the Paleozoic

rocks were folded, which is generally assigned to the close of the Cre-

taceous period, but he says “It seems to be a fact that the Lower Eocene

(Wasatch) sediments cover the outcrop of the overthrusts in several

places, thus indicating that the folded and overthrust structures had been

deeply eroded.” It is quite likely that these two districts less than fifty

miles apart suffered overthrusting at the same time and that whatever

period is deduced for one will be found to be the same for the other.

%C, Kina: U. S. Geol. Expl. 40th Par., Vol. I, p. 304.

% EK. BLACKWELDER: ‘‘New Light on the Geology of Wasatch Mountains,” Bull. G. 8.

AGy Vole v2). Derooo-

136 ANNALS NEW YORK ACADEMY OF SCIENCES

From southeastern Idaho and northern Utah, Richards and Mansfield*®

have described a great overthrust which involves strata of late Cretaceous

age. The oldest rocks which have been found concealing its trace are

the early Eocene conglomerate of the Almy formation,*? making the

possible range of age from late Cretaceous to early Kocene. ‘This agrees

closely with Blackwelder’s determination for the Willard overthrust near

Ogden, Utah.

The latest beds involved in the Alta overthrust are Pennsylvanian

within the area studied, but from the general fact that overthrusting

accompanies or follows strong folding, the overthrusts of the central

Wasatch must belong to the late Mesozoic and are probably of the same

age as the great Willard and Bannock thrusts.

The trace of the Alta overthrust has a trend north-northwest, while

the thrust surface dips strongly to the east with the general monoclinal

structure of the region. ‘This leads to the belief that the movement was

from east to west, though this is only tentative. The overthrust block

seems to be continuous for eight or ten miles to the east, where it disap-

pears below the quaternary beds of Kamas and Weber valleys. More

extended work will be needed, however, to show definitely that the direc-

tion of thrusting is as above indicated.

Blackwelder thinks the overthrusting near Ogden came from the east,

but Richards and Mansfield have questioned the correctness of this de-

termination, as they believe it came from the west. There is thus a

difference of opinion in a region perhaps better adapted to the determina-

tion of this question. It might be said, however, that the unsymmetrical

anticlines of the Cottonwood region are steepest on the west, and in one

or two cases seem to be overturned in that direction, suggesting strong

lateral pressure from the east.

The structural relations along the trace of the Alta overthrust are

shown in the structure sections accompanying the geologic map.

A Minor Overthrust

Immediately south of the town of Alta there is a mass of limestone,

shale and quartzite which stands nearly vertical, dipping slightly to the

west. In Collins’s Gulch, the strata dip eastward at an angle of about 25

degrees. Across the ridge to the east of the Albion tunnel, the quartzites

appear again with an eastern dip. There is thus between Collins’s Gulch

and the great cirque south of Alta, a mass of limestone, shale and quartzite

, ©R. W. RicHarps and G. R. MANSFIELD: ‘‘The Bannock Overthrust,’’ Jour. of Geol.,

Vol: (20; No: 8: 1912:

“U.S. Geol. Surv. Prof. Paper No. 56, p. 89.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 137

which is overturned and does not match with the lower beds on either

side. All attempts to explain the structure as a syncline, or overturned

anticline, fail when the succession of beds is noted, leaving the only rea-

sonable basis of explanation that of an overthrust block.

Faults

In a region of such complicated structure, faulting may be expected

to occur. Dislocations are met with in every mine, but those on a big

scale are few in number. Whether large or small, they appear to belong

to two systems of fracturing, but movement has probably occurred more

than once in each system. The directions of these two sets of fractures

are respectively north-east and south-west for those carrying the ores and

dikes, and northwest-southeast. These correspond to the dip and strike

of the Alta monocline and may therefore be classified as dip faults and

strike faults.

The earliest displacements are those in which the fissure veins carrying

the ore were found. ‘These have a fairly constant direction, N. 70° E.,

and no doubt belong to the same period of fracturing which gave rise to

the lode deposits of the Park City district which he in the path of their

northeastward extension. Into some of these, the dikes which are com-

mon in the southern part of the district were injected, and it is thought

that the ore-bearing solutions came up in others at the same time, or

immediately following, depositing the ores. The displacements above

this first set of fractures do not appear to have been very great. They

are probably more in the nature of great cracks which were formed

through the effects of intrusion of the larger bodies of igneous rock to

the east and west, as inferred from the correspondence of their direction

with the general trend of the intrusives. On the other hand, when com-

‘pared with the general dome structure of the region they are radial and

might be considered as tension cracks made when the region was thrown

into its present arched condition.

After the formation of the ore deposits of the district in the northeast-

southwest fissures, a second period of faulting occurred, having a trans-

verse direction to the first set of fractures. This is shown in the north-

west-southeast faults encountered in many of the mines, where they in-

variably displace the ore bodies. A notable case is the great Atwood

“slip” which cut out the ore of the famous Emma mine. Many other

examples are known in the various mining properties.

The displacements of these strike faults are much greater than those

of the earlier fractures. The one occurring in Superior Gulch running

north into South Fork appears to have the greatest throw and has been

138 ANNALS NEW YORK ACADEMY OF SCIENCES

called the Superior fault. A second one of great size cuts across the

ridge from the head of Silver Fork into the Alta basin. It is seen most

clearly on the ridge northeast of the Emma mine, where the fault breccia.

has weathered into relief, standing up like a great wall. This fault will

be described as the Silver Fork fault. In all of these movements, the

displacements are more in the vertical direction, WE shifting’ being

not so frequently met with.

Superior fault——The Superior fault as shown upon the map (Plate

VI) can be traced from the mouth of Superior Gulch in Little Cotton-

wood Canyon northward into South Fork. On the top of the ridge, it.

is clearly marked by a wall of breccia which stands up ten feet above the

general level of the surface. The crushed zone marked by the breccia

may be followed northward for nearly a mile. In the upper tunnel of

the Cardiff mine, it is well shown for a distance of a thousand feet along

which the hanging wall is quartzite and the foot wall very hard limestone.

From all indications in South Fork, where it was first encountered, it

may be explained as a normal fault with a throw of about a thousand

feet, but observations from the Alta side of the divide clearly show it to

be a reverse fault of less magnitude, the displacement being about 600

feet. The limestones on the west are lifted. They belong to the lower

series exposed on the east wall of Superior Gulch and not to the lime-

stones of the Reade and Benson ridge as at first supposed. This was not.

understood until the overthrusting which duplicated part of the series.

was discovered at Alta. The limestones are all of the same age but they

occur in two series separated by nearly a thousand feet of older quartzite

belonging to the overthrust member. The faulting is clearly of later date

than the overthrusting. The understanding of this relationship is of the

utmost importance to the mining people of South Fork, who have never

suspected the presence of a limestone series below the quartzites of the.

Reade and Benson ridge. The cherty limestones forming the ridge south

of the Cardiff office and boarding house are the lifted, westward extension

of that lower series upon which the overthrust block rests. The relation

is clearly brought out in Section A-A, Plate VI (see also Plate III).

The direction of this movement is more nearly vertical than horizontal

though the oblique flutings on the walls in the Cardiff tunnel indicate

an important horizontal component toward the north on the west side.

Surface evidence of faulting cannot be traced farther than the Cardiff

mine to the northward, though it is safe to assume that a movement so

pronounced at this last observation point must have continued for some

distance beyond. At a point about a mile and a quarter north of the

Cardiff, the bottom of South Fork is composed of limestone, and no

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 139

evidence of faulting could be found; but on the north wall of Big Cot-

tonwood Canyon opposite South Fork, faulting is clearly shown, Here

the west block has gone down instead of up. If this fault has anything

to do with the Superior fault, it must be in the nature of a pivotal fault

with the fulerum somewhere between the Cardiff mine and the mouth

of South Fork.

Silver Fork fault—At the head of Silver Fork of Big Cottonwood

Canyon, ‘on the ridge north of Alta, there is a wall of limestone breccia

which stands up from 10 to 20 feet above the crest of the ridge, having a

direction nearly north and south. On both sides of it are limestones, but

their metamorphic condition prevents close observation as to the strati-

graphic displacement because of the difficulty of identifying a suitable

datum plane on both sides. Farther to the south in the gulch leading

from Alta to the City Rocks and Alta Consolidated mines, the quartzite

and shale of Cambrian age are faulted up on the east so that they are in

contact with the limestones which normally overlie them. The displace-

ment is estimated to be between 500 and 600 feet, though the exact

amount of movement could not be readily determined. It is, however, a

fault of considerable magnitude. The fault surface seems to be vertical,

and it is therefore impossible to say whether it is of the normal or the

reversed type. Minor parallel faults may easily be detected to the west

along the top of Emma Hill and Flagstaff Mountain, but on account of

the strongly metamorphosed condition of the limestones, the throws have

not been determined. They are, however, thought to be only slight. It

might be said by way of generalization that the block between the Su-

perior and Silver Fork faults has gone down and that the west end ap-

pears to have been most depressed. The parallel fractures between them,

therefore, may show that the west side has gone down in most cases.

This, however, is merely a suggestion and may not be true in all cases.

Minor faults—In the various mines of Alta, minor faults are known

to be of frequent occurrence. They conform generally to the main direc-

tions of fracturing already referred to as northeast-southwest and south-

east-northwest. The latter are invariably found to be younger than the

northeast-southwest series of faults. The Columbus Extension tunnel

has been driven northwest for a considerable distance along one of these

breaks. Near the mouth of the tunnel, a displacement of 90 feet has

been observed, but farther to the north it is probably less. On.the divide

between South Fork and Alta, a fault with a throw of about 30 feet is

clearly shown on the surface. The west side has been depressed. This

fault is shown in the structure sections B-B* and C—C on the map.

140 ANNALS NEW YORK ACADEMY OF SCIENCES

South of the Columbus Extension, in the Alta Hecla property, several

of these north-south vertical faults are to be seen underground. Pros-

pecting along them has failed to develop ore except where the northeast-

southwest fissures have been crossed. In every case, these ore-bearing

fissures are offset, showing them to be older. The amount of shifting has

only been worked out in the one case above cited, as far as known, but

generally the displacements are not very great, except in the two large

faults already described.

SUMMARY OF CONCLUSIONS

PHYSIOGRAPHY

(a) The central Wasatch is a maturely dissected block mountain, pre-

serving in a modified condition the form of its original profile.

(6) Before the Wasatch fault was formed, the folded Wasatch forma-

tions were planed off by erosion, and several plutonic igneous masses

were uncovered, notably the Little Cottonwood granite, the Alta grano-

diorite and the Clayton Peak quartz diorite stocks.

ranges, and at the same time the Wasatch block was uplifted. When

newly formed, it had a steep western face and a long gentle eastern back

slope.

(d) The original crest line was the upper edge of the great fault es-

carpment on the west. This was also the original divide.

(e) The divide has migrated from its first position near the western

margin to its present position near the eastern margin of the block. The

present long west-flowing streams of such canyons as Big and Little

Cottonwood are chiefly obsequent streams, being consequent near their

mouths.

(f) The crest line has moved in the same direction as the divide, but

only a short distance.

(7) The Provo and Weber Rivers are probably also obsequent streams

in their canyons across the Wasatch. ‘Their head-waters are the eastern

consequents that have been captured, so far as the drainage of the

Wasatch is concerned.

(h) The mature dissection of the Wasatch by stream action was ac-

complished before the Pleistocene. Upon the stream-cut topography

certain features were superposed due to glaciation during the Pleistocene.

Later modifications have been slight. .

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 141

STRATIGRAPHY

(1) The major part of the great quartzite and slate series exposed in

Big Cottonwood Canyon is Algonkian and possibly Lower Huronian in

age. |

(j) The Lower Cambrian is separated from the Algonkian by a heavy

basal conglomerate of widespread occurrence. The Cambrian strata of

the central Wasatch belong to the lower and middle divisions of the Cam-

brian system and are less than one thousand feet thick.

(k) Above the known Cambrian are about 500 feet of unfossiliferous

limestones and calcareous shales provisionally referred to the Ordovician.

Silurian strata are entirely wanting in the Cottonwood region.

(1) Middle and Upper Devonian horizons are represented by what ap-

pears to be an unbroken succession of limestones carrying faunas closely

allied to those found in western Colorado and Iowa.

( m) The Devonian beds rest with disconformity upon the lower lime-

stones and are separated from them by a thin bed of conglomerate com-

. posed of limestone pebbles.

(n) The Mississippian follows the Devonian conformably and is repre-

sented by limestones of Lower and Middle Mississippian age which are

separated by a continental formation.

(0) In the Cottonwood region, there is an unconformity between the

Mississippian and the Pennsylvanian (Weber quartzite) which follows,

representing a considerable erosion interval. The thinning of the Weber

quartzite is probably to be accounted for by overlap upon this erosion

surface.

(p) The Wasatch limestone of the Fortieth Parallel geologists em-

braces strata of Ordovician, Devonian and Mississippian ages. The

Ogden quartzite and Ute limestone of supposed Devonian and Silurian

ages respectively have no existence, as originally defined, in the central

Wasatch.

STRUCTURE

(q) In the vicinity of Alta there is a great overthrust, presumably

from east to west; the overthrust block consists of beds ranging in age

from Algonkian through the Paleozoic and Mesozoic; the underthrust

member consists of Devonian and older beds.

(r) The age of the overthrust is probably the same as the main fold-

ings of the Wasatch, generally assigned to the end of the Cretaceous. -

142 ANNALS NEW YORK ACADEMY OF SCIENCES

(s) After the overthrusting occurred, there followed a period of in-

trusion in which large irregular granitic and dioritic masses together

with numerous dikes were injected into the Mesozoic and older forma-

tions.

(t) North-south faulting near Alta has resulted in the formation of

two master faults and numerous minor fractures. These run roughly

parallel to the main Wasatch fault line and probably belong to the same

period of readjustment.

BIBLIOGRAPHY

PHYSIOGRAPHY

Atwoop, W. W.: Glaciation of the Uinta and Wasatch Mountains, hes U.48:

Geol. Surv. Prof. Pap. No. 61. 1909.

Davis, W. M.: Ranges of the Great Basin: Physiographic Evidence of Fault-

ing. Sci., Vol. XIV, pp. 457-459. 1901.

Emmons, S. F.: Rept. U. S. Geol. Surv. 40th Par. Descr. Geol., Vol. II. 1877.

GEIKIE, A.: Ancient Glaciers of the Rocky Mountains. Am. Nat., Vol. 15, p. 3.

1881.

GILBERT, G. K.: Geographical and Geological Explorations and Surveys West

of the 100th Meridian, Vol. III, pp. 17-187. Washington, 1875.

: Lake Bonneville. U. S. Geol. Surv. Monograph I.

JOHNSON, D. W.: Block Mountains in New Mexico. Am. Geol., Vol. XXX, pp.

135-1389. 1908.

KING, CLARENCE: Rept. U. S. Geol. Surv. 40th Par. Sys. Geol., Vol. I. 1878.

LE ConTE, JOSEPH: Origin of Normal Faults and of the Structure of the Basin

Region. Am. Jour. Sci., 3rd Ser., Vol. XX XVIII, p. 257. 1889.

RUSSELL, I. C.: Geological History of Lake Lahontan. U. S. Geol. Surv.

Monograph XI. 1885.

Spurr, J. E.: Origin and Structure of the Basin Ranges. Bull. Geol. Soc. Am.,

Vol. 12, pp. 217-270. 1901.

STRATIGRAPHY AND PALEONTOLOGY

BERKEY, C. P.: Stratigraphy of the Uinta Mountains. Bull. Geol. Soc. Am.,

Vol. 16, pp. 517-530. 1905.

BLACKWELDER, E.: New Light on the Geology of the Wasatch Mountains. Bull.

Geol. Soc. Am., Vol. 17, pp. 517-533. 1910.

: Handbuch der Regionalen Geologie, Vol. 8, Pt. 2, p. 136. Heidelberg,

1912.

BouTwELL, J. M.: Geology and Ore Deposits of the Park City District, Utah.

U. S. Geol. Surv., Prof. Pap. No. 77, pp. 41-65. 1912.

Emmons, S. F.: Rept. U. S. Geol. Expl. 40th Par., Vol. 2, p. 342. 1877.

Girty, G. H.: Carboniferous Formations and Faunas of Colorado. U. S. Geol.

Surv. Prof. Pap. No. 16. 1903.

HINTZE, GEOLOGY OF WASATCH MOUNTAINS, UTAH 143

KINDLE, E. M.: Silurian Faunas of Western America. Am. Jour. Sci., Vol. 25,

pp. 127-128. 1908.

: Devonian Fauna of the Jefferson Limestone. Bull. Am. Pal., Vol. 4,

No. 20. 1908.

KING, CLARENCE: Rept. U. S. Geol. Expl. 40th Par. Sys. Geol., Vol. 1. 1878.

PEALE, A. C.: U. S. Geol. Surv. of Mont., Ida., Wyo. and Utah (Hayden), pp.

105-108. 1872.

TENNY, S.: Devonian Fossils in the Wasatch Mountains. Am. Jour. Sci., 3rd

Ser., Vol. 5, pp. 189-140. 1873.

Watcort, C. D.: Second Contribution to the Studies on the Cambrian Faunas

of North America. U. S. Geol. Surv., Bull. No. 30. 1886.

: Cor. Pap., Cambrian. U.S. Geol. Surv. Bull. No. 81. 1891.

: Cambian Sections of the Cordilleran Area. Smith Misc. Coll., Vol. 53,

No. 5. 1908.

STRUCTURE

BLACKWELDER, E.: New Light on the Geology of the Wasatch Mountains, Utah.

Bull. Geol. Soc. Am., Vol. 17, pp. 533-542. 1910.

BoutwEL., J. M.: Geology and Ore Deposits of the Park City District, Utah.

U. S. Geol. Surv. Prof. Pap. No. 77, p. 48. 1912.

Dana, J. D.: Rocky Mountain Protaxis and post-Cretaceous Mountain Making

Along Its Course. Am. Jour. Sci., 3rd Ser., Vol. 40, p. 187. 1890.

Emmons, S. F.: Rept. U. S. Geol. Expl. 40th Par., Vol. 2. 1877.

: The Wasatch Mountains and the Geologic Panorama of the Wasatch

Range. Comp. Rend., Int. Geol. Cong., 5th Ses. 1891.

: Little Cottonwood Granite Body of the Wasatch Mountains. Am.

Jour. Sci., 4th Ser., Vol. 16, pp. 189-147. 1903.

GEIKIE, A.: Archean Rocks of the Wasatch Mountains. Am. Jour. Sci., 3rd

Ser., Vol. 19, pp. 363-367. 1880.

GILBERT, G. K.: The Wasatch, a Growing Mountain. Bull. Wash. Phil. Soc.,

Vol. 2, p. 195.

: A Theory of Earthquakes of the Great Basin. Am. Jour. Sci., 3rd

Ser., Vol. 27, pp. 49-53. 1884.

Hitts, R. C.: Orographiec and Structural Features of the Rocky Mountain

Geology. Proc. Col. Sci. Soc., Vol. 3, pp. 362-388, 400. 1891.

Kine, CLARENCE: Rept. U. S. Geol. Expl. 40th Par. Sys. Geol., Vol. 1. 1878.

RicHaRps, R. W. and MANSFIELD, G. R.: The Bannock Overthrust: A Major

Fault in Southeastern Idaho and Northeastern Utah. Jour. Geol., Vol.

XX, No. 8, pp. 681-709. 1912.

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PLATE I

A. LOWER HALF OF SOUTH FORK OPPOSITE MILL D. BIG COTTONWOOD CANYON,

LOOKING NORTH

Shows broad U-shaped glacial trough, with terminal moraine at the junction

of the main canyon

B. CONGLOMERATE AT THE BASE OF THE CAMBRIAN QUARTZITE IN LITTLE COTTON-

WOOD CANYON, JUST BELOW ALTA

1 WTAAD

VOYMAD GOOWKOTTOO DIA .a LUM arTia0owio AXOT HTV0A TO WIA SUWOI iA

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ANNALS N. Y.

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F . . PLATE II

A. PHOTOMICROGRAPH OF “‘TILLITE’ FROM THE HEAD OF SOUTH FORK

Showing rounded and angular fragments, chiefly quartz, in a dark matrix,

principally biotite. Enlarged 25 diameters

B. PHOTOGRAPH OF HAND SPECIMEN OF “TILLITE’” FROM SOUTH FORK

Showing rounded quartzite pebble in black groundmass. Natural size

aot ¥rv0a 40 dAdH aHT wom "arn ‘40 esaomonacnont .

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ANNALS N. Y. Acap. Sc1. VOLUME XXIII, Puate II

PLATE III .

‘A. THE DIVIDE AT THE HEAD OF SOUTH FORK AND THE GEOLOGIC EXPOSURES OF

THE SOUTH END OF THE READE AND BENSON RIDGE

Showing the overthrust members above the Superior fault

B. NEAR VIEW OF THE UPPER CENTRAL PART OF FIG. A

Showing, from left to right, the Cambrian shale, Cambrian quartzite, Algonkian

“conglomerate” and quartzite

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ANNALS N. Y. AcAD. Scr, VOLUME NXT, Pruaty Trl

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PLATE IV

A. ALTA OVERTHRUST AND GEOLOGIC EXPOSURES ON THE NORTH SLOPE OF LITTLE

COTTONWOOD CANYON

Showing the duplication of beds. Looking north

8. NEAR VIEW OF THE EAST-SLOPING ALGONKIAN QUARTZITE SHOWN ON THE RIDGE

OF FIG. A

Showing the crumpled layers of hard quartzite

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ANNALS N. Y. ACAD. SCI. VOLUME XXIII, Puare 1V

PLATE V

TOPOGRAPHIC MAP OF THE ALTA REGION, WASATCH MOUNTAINS, UTAH

The southwestern part of the Cottonwood Special Sheet, U. S. Geological Survey

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ANNALS N. Y. ACAD. SCI. VoLuMr XNIII, Prater V

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PLATE VI

GEOLOGIC MAP OF THE ALTA REGION, WASATCH MOUNTAINS, UTAH

With structure sections, showing the relation of the Superior fault to the

Alta overthrust

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{

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Lie?

poet a oe

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rt a SBE Te

Toeee i we)

eh ee ree ee

) NE a

LOCKATONG FORMATION OF THE TRIASSIC

OF NEW JERSEY AND PENNSYLVANIA

ANNALS OF THE NEW YORK ACADEMY OF SCIENCES

Vol. XXIII, pp. 145-176, pl. VII

Editor, EpmMunD Otis HovEey

A. C. HawkKIns.

ee ted

PRQinan TST >

JUN 18 7

NEW YORK

PUBLISHED BY THE ACADEMY

27 JANUARY, 1914

THE NEW YORK ACADEMY OF SCIENCES

(Lyceum oF Natura History, 1817-1876)

| OFFICERS, 1913

President—EMERsON McMItuIn, 40 Wall Street

Vice-Presidents—J. EpDMUND WoopMAn, W. D. MatTHEew

CiraARLES LANE Poor, WENDELL T. BusH

Corresponding Secretary—HeEnry E. Crampton, American Museum

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[ ANNALS N. Y. Acap. Scr., Vol. XXIII, pp. 145-176, Pl. VII. 27 January, 1914]

LOCKATONG FORMATION OF THE TRIASSIC OF NEW

JERSEY AND PENNSYLVANIA?*

By A. C. HAWKINS

(Presented by title before the Academy, 29 September, 1913)

CONTENTS

Page

MA eR ee SS pete. © & sin he aoavGra es Woe aa mien oes os owas aw cele awed en ew wie 145

EI ae es Se ee ee ee ea 146

Distribution and topography....... 6... cece eee eee eee ee eee eens 146

NNR eR les AS Kars Sh pin dnics & bic) 54 'ej3¢m im O\ni is (B}a'¥ 6 Dev dialer Ble ele wa 147

te eh ee ea vio rs ices Roa Sw as ss Ceid nig pale ea eale eee 149

Re SR ere oa hd dig sab m8 SSID Sb Ce sae © oe cie nw Bidelen woe ele 80 151

RM IIIERE PRE TIITSUT Yor 02 oo, Fc enero n sw ele c\sene dias sence se wae wlale apace ee 155

ererminations of irom in the Lockatong argillites.............0cec.ceee 156

Le ee ore aa Meh eaet re SES oY uel hua afin iad-@ Wialre te inate 158

ee em ecmrara ghd UM EG: SECON GS 2... csc « ws 3 wwe sore ww eee renin eet a sacle 163

ee NS alee ig ac dn cute, ¢ wip’ Ae aie a0 <a sped > oe Sele dh wos ae 166

odin rie als w ole kad gc ee ars Ree we a eee ee 172

EE EE TEI a 172

reer gfe eet a NE Seb ne Ue ees ia ew iln' sain wel eee ae ae ees 173

INCE CE Gureaer ea ot har hohe Gas Glas fapalle wee biked Vane ecliniein viele we bee 175

INTRODUCTION

The study of a recently exposed zone of mineralization in an argillite

quarry at Princeton, New Jersey, led the writer to extend his investiga-

tions to certain interesting features of the rock formations and general

tectonics of the region, a full knowledge of which was found to be essen-

tial to the elucidation of the original problem.

The statements herein made are based largely upon observations made

during personal field work by the writer from 1910 to 1912. These data

have been supplemented by additional facts supplied in publications of

the State and national geological surveys, and by work in the petro-

graphical and chemical laboratories of Princeton University.

A bibliography of the publications that furnish the most important

references is to be found at the close of this paper.

Grateful acknowledgment is hereby made to those who have in various

ways aided in the accomplishment of this work, including members of

1 Manuscript received by the Editor, 23 September, 1913. (145)

LER nian | Thst Stiigo~.

146 ANNALS NEW YORK ACADEMY OF SCIENCES

the faculty of the Department of Geology at Princeton University, Dr.

Edgar T. Wherry of Lehigh University and Dr. L. Hussakof of the

American Museum of Natural History, New York City.

HIsTorRY

The Lockatong formation is the middle member of the sedimentary

series of the Triassic system, as exposed in the adjacent parts of New

Jersey and Pennsylvania. Elsewhere throughout the Triassic of eastern

North America it is unknown.

The earliest reports dealing with the rocks of this formation mention

them only in connection with the quarrying industry of the region.

Thus, in the Annual Report of the State Geologist of New Jersey for_

1880 (p. 24), a short statement is made concerning Stephen Margerum’s

quarry in Princeton, which was first opened in 1845. In the issue of this

publication for the following year (p. 55), a similar allusion appears.

F. L. Nason’s discoveries of: fossils from the Triassic, reported in 1888

(idem, p. 28), include those found in the Lockatong beds. B.S. Ly-

man? wrote a report on the New Red of Bucks and Montgomery Coun-

ties, in which the rocks of this middle member are described and named

Gwynedd shales. Because however this term was made, on the map at

least, to cover rocks clearly referable to other formations, it seemed best

to the New Jersey geologists to rename the formation, and in the de-

tailed report Dr. H. B. Kiimmel* proposed the term Lockatong, which is

now generally used. This was further supplemented by an even more

detailed paper, published by him in his report for the following year.*

In 1908, Professor J. Volney Lewis made a careful investigation of the

argillites of this series, the results of which were published in the State

Geologist’s Report for that year (p. 94). Since that time, descriptions

of the Lockatong have appeared in the Philadelphia Folio (No. 162),

and in the Trenton Folio (No. 167), of the United States Geological

Survey, in both of which excellent geological maps of the respective areas

are given.

DISTRIBUTION AND ‘TOPOGRAPHY

The rocks of this series lie in a slightly curved belt extending from a

point some ten miles west of Phoenixville, Pa., to the border of the Cre-

taceous formation about ten miles northeast of Princeton, N. J. (See

2Summary Final Report of the Second Pennsylvania Geological Survey, vol. 3, part 2,

p. 2610. 1895.

3 Rept. State Geologist of N. J., 1896, p. 40.

4 ITbid., 1897, p. 36.

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 147

Plate VII.) The general trend of the belt is thus northeast and south-

west, in harmony with that of the local Triassic in particular, and that

of the pre-Triassic rocks and of the Appalachian highlands in general.

The course of the Lockatong belt is usually marked by a ridge whose

long axis corresponds with the strike of the formation. This ridge com-

monly has a relief of fifty to a hundred feet or more above the surround-

ing Triassic area, which is underlain by the somewhat less resistant rocks

of the Stockton and Brunswick series. At Phoenixville, it is traversed by

two railroad lines, which cross it by means of open cuts and tunnels.

Three railroads cross it between this point and the Delaware River, and

each of these has required much excavation, At Byram, Hunterdon Co.,

'N. J., there is a long, persistent series of bluffs flanking the river for a

distance of four miles, the cliffs at certain places being exceedingly steep

and rugged. Between the Delaware and Princeton the topographic effects

are not so pronounced. At Princeton the hard rocks, though not very

thick, form a ridge, upon which the town has been built.

Upon the Lockatong ridge there is a heavy yellow clay soil, which is

typical of the formation. In it are seen many irregular, splintery frag-

ments of resistant dark-colored shale and argillite. These argillite frag-

ments, after a considerable period of exposure to the air, often develop a

brown or yellow greasy surface, due to the production of kaolin, which

gives rise to the typical sour soils of this belt. These soils, however, are

fertile. The high land overlying the Lockatong beds supports an abun-

dance of timber, which, throughout much of the area, has been cleared

away to make room for prosperous farms. The drainage is active, and

most of the larger streams cut directly across the hard rock ridge.

STRATIGRAPHY

The portion of the Triassic system exposed in this part of the country,

usually referred to as the Newark, is composed of three distinct parts or

units, which, named in order from the bottom to the top of the series,

are the Stockton, the Lockatong and the Brunswick formations. The

Stockton formation is composed of coarse conglomeratic sandstones of

light colors, usually interstratified with red shaly beds. The Lockatong

series of dark-colored, fine grained mud-rocks is the one herein described.

The Brunswick formation consists of a very thick succession of red shale

beds with some portions that are heavy bedded sandstones, and some-

times well developed conglomerates. The total thickness of the Triassic

rocks in New Jersey is estimated to be 18,000 feet. The larger portion

of this thickness is made up of red or reddish brown shaly and sandy

148 ANNALS NEW YORK ACADEMY OF SCIENCES

rocks. The dip, which is fairly constant, averages about 15 degrees

northwest, which is normal for the whole system in this vicinity.®

The Lockatong formation is thickest in the middle portion of the

belt, as appears very plainly when the whole belt is mapped together

(Pl. VII and Fig. 1, p. 149). Exposures along the Delaware River® fur-

ther prove that it steadily thickens for some distance westward. Sections

of the formation are shown by the river at an average distance of eight

miles apart, east and west, on account of the repetition of the beds due

to the great Flemington and Hopewell faults, which together have a

throw of approximately 17,000 feet. West of Phoenixville, the Locka-

tong rapidly narrows and finally terminates in a thin edge, its horizon

being taken by a heavy conglomerate, apparently of Brunswick age.

Northeast of Princeton it narrows considerably; northward of this point,

it is hidden beneath a covering of later sediments of Cretaceous and

Pleistocene age. Its total failure to re-appear twenty miles farther

north, where only the softest of red shales are exposed, has led to the

belief that its northward termination is perhaps much like the southern

one west of Phcenixville. From these observations, it appears that the

Lockatong is a deposit of a decidedly lens-like character. A comparison

of the area of the Stockton formation with that of the Lockatong,

throughout the extent of the latter, shows that the Stockton varies with

the Lockatong, widening and narrowing with it.

The Lockatong consists of a thick series of exceedingly fine grained

and close textured rocks. The sediments were so thoroughly sorted that

scarcely a single coarse textured layer is to be observed among them in

the field. The rocks as they now exist appear as massive, fine grained

argillites and shales, the former, on account of jointing, often forming

“flagstones” or more massive blocks. The “slates” are often friable,

having a cleavage which is too uneven to afford good roofing slate. The

color of the shales and of the argillites may be gray, reddish brown,

black, or olive green. Red and gray colors often alternate on a large

scale. Impure limestone layers one or two inches thick occasionally

appear.

The bedding of the Lockatong argillites and shales is very uniform,

although a slight irregularity is sometimes present in the bedding of

shaly layers. No cross-bedding appears. Ripple marks and mud-cracks

occur, the latter sometimes abundantly, in the upper and lower portions

of the series.

5A detailed description of this series is given in the Trenton Folio, No. 167, United

States Geological Survey, p. 7.

6 Tbid., Geological map.

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 149

LOCK ATONG

FORMATION

BRUNSWICK

STOCKTON

TORMATIONS

iG. 1.—Geological sections across the Lockatong formation from northeast to southwest

Where continuous exposures are available near

Princeton, the succession of beds usually can be ob-

served to be about as follows: At the lowest portion

of the section examined (as in McCarthy’s quarry,

Princeton) there is a thick series of strata of dense,

reddish brown, flaggy argillite. At its upper limit

the brown bed suddenly loses its characteristic color,

and passes, without change in other respects, into a

dark gray rock, the most typical argillite of the series.

A short distance higher up in the dense gray rock,

radiating crystal growths occupy a horizon about a

foot thick, with irregularly scattered white crystal

specks in the layer immediately above, as hereafter

described. Above this horizon there is apt to be an

inch or so of very black, carbonaceous shale, followed

by one or two inches of a light gray, thoroughly crys-

talline magnesian limestone. This is again succeeded

by an inch of black shale, above which there are gray

argillite beds. Still higher more red rocks may ap-

pear, and the whole series, as above described, may be

repeated.

COLUMNAR SECTIONS

Columnar sections of the Lockatong series are

shown in Fig. 1. The,sections are numbered from

1 to 7, beginning at the west. They are arranged im

order of occurrence, being spaced at approximately

correct relative distances horizontally. The vertical.

scale is made, for convenience, ten times the horizon--

tal. The datum plane selected for correlation of the:

various sections is the top of the massive argzllites,..

whose deposition marked the time of steadiest sedi--

mentation and most sluggish drainage, which in turn:

signifies a nearly level surface throughout the area..

It is to be noted that this arrangement brings the:

prominent Hstheria beds, near the base of the three

western sections, to about the same level. The transi-

tion beds are represented by black bands where they

occur, in the upper and lower part of each section,

and the outline of the basin has been completed to

show how a repeated interdigitation of the Stockton

150 ANNALS NEW YORK ACADEMY OF SCIENCES

below and the Brunswick above with the Lockatong might account for

the areas of transition.

0. This part of the basin is underlain by dark-colored shales; no argillites

appear. At the western end there is a heavy conglomerate, probably of

Brunswick age.

4. Reading Railroad tunnel section, Phenizville. Feet

Shale; dark red. to:black (top bed). sce eet sis estoie ease tecdaysue eas rena 380

Shale: WrOwW A «(chi iosc s ols Bese eee oleic s ne vetars) ale OMe ee pec ee eee 380

Argvillite, “Drow: 2s). sccis scar eheke ¢are cere tiene breve serene ate tec tcy aceon 250

Whaile,..sandy, red and HOW 4) 6.2 a 50k ees © Oleiere ee encte toa iatel Gemebieae

(Black shales with eStheriees jz sic saccyal siete sine tae 10s sere pol ouerereuenete sete ene veeel arene | 490

Shale, red and brown, transition beds (bottom bed)............. J

Total, (no: important fanliimey! oe la eater rene inrenere eat 1500

2. Schuylkill River section, Phenizville.

Shale-and argillite, brown: (top, bed)... sheik s see ee eee 750

Shale, black, with fish seales......... Ls creck nslie ele ouctelo ntete Cieenec nec: tear 5O

ALOU Wite, DROW sii.\s oeseevel dG eee eter ene owe ere nteseer abate cele tous tehateds lokeacieesreretcuemcian: 500

Shale: ‘dark ‘colored; ‘wathvesthertee:. ..:.02%, an et eid cee ie oe oh oe ee ees 20

Shale; dark red “Gbottorn MOG) ei22.c Giaie s:cyeucea ions ecu ehtexecctiepone cote or oereieteeattale 380

‘Potal CuO: Lait We). 2 cites eleven foreun eens Seve carete erereonate aden teens 1700

3. Perkiomen Railroad section.

Shale; dark red’ (iGp Ded: sos oes ort ah @ acini wie ae Oe See eee 750

ATU Ce, DEO WARE 24, deacenial 65) ays Gre coropslins ene taneun tee ores ve pote Teneo eeere ne tae pene 500

BOIS) Wit CSUSB aye se 5 ce! pihs io eau sah Ses) atatichicllc havens ious oxcleya eater eiele neue io tee eae 10

AT OUNCES, LOW r.)<, 5.0 5000 wate we Gr heist whee ein ere ello eleva Nee meten Crete event ae 330

shale, bard andined 2.4. sine ¢olek posececie oes eve ee einie seek: Ree 330

Shale, ray, With esther: .c.c-+.ccastee nts See eke aches Oe Gee ee 10

Shale, dark red -«Gbottom) Ded): ..6o0..s.c sie sista erectus ee ee einen 200

Probably no important faulting.

FPO CAI oa dba cu eee Peiees NG: a leller Dis oie Ihe ee tele eS Tete SEER nse eee 2140

4. Gwynedd Valley section, Philadelphia and Reading Railroad.

Shale, dark: red-(top DEG)... sols oe aie Reena a Geeta © cuerte ere career 720

ATAU Ce, DEO Wize pve dynes ie loss 0 4 soe fale seta ec ead ORE ete ie ee Clee nie See 1000

Shale ‘dark red ‘(bottom Bed) c.......-c.0seuute sites seit eee 1000

10 per cent reduction made for faults.

POCA a 5 5 Fle ioG) eerste dere eve by foes erate Rnoeaicane tp paitete tea ain de Rite oan nedt ye area 2430

5. Wycombe section, Philadelphia and Reading Railroad.

Shale, dark red. (top DEG): skisde eens tee oleae tice treater 670

Limy layer with estherizw, scales and ostracodS...............20- 1

Arcillite, gray Ani IDKOW foes. hace cic bis sit were dare laies Meares ieee rate eee eee 1000

Argillite, with magnesian Jimestone Dands2: ..).),.2)) 0.26 eee eee 50

Shale, POW. aiccie wisn So see age onus area ayer ARO MOTE eRe inn one 600

HAL], TODS sale eee ole c Scrat ror tue te coy Sesletameoethn lettatcat Saket ie anne en ene ae 450

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 151

Feet

Senda Deus, STECM ANG FOMOW nace ee wel ve ob Seis bce wmalsieg ss 60

Arcillite and shale, hard and red (bottom bed)..........6..c00.0: 190

Fault of 1000 feet at the top.

10 per cent reduction made for other (undetected) faults.

LS | pele BE ES EN Re AL So a 2700

6. Scudders Falls section, Delaware River.

Shale, dark colors, alternating at top with red shale (top bed)....

Per UTGCe UAC TNL SPMEEIG: sro leicin chee rleis osetel ciara s,5 a ait none ea ee agate acess Oe ©

SAE ML GE TORI thy hc cate Mayet as aie ee Pees) etans, of tate eal Ste (aia, wt eote ie <i sa ch alata) et stave te 192

SUERa NANI Sa et chee Sener Sake ery) nin, wae RPA erode oh kL 8s, Suse sueaal RIG oe se)s 6 Busha Bie

Pee EM IOs VAG ECPI cheep 'a 5-3 spate ais asus wislie\oes ave autho aaah cee odie tein bs |

Shale black, oreen, cray, etc..( bottom bed). 2... .0.6. 00 see ee ees 1183

No faulting observed.

PRG Tee Tanne eh ve rete @ eae Sl OMG: alle ele Systane Ghsiaeg Mis See a hats 1975

7. Princeton section.

Shales, red, and argillite, red-brown (top bed).................. |

Os LES, PETSEAY See IRIS nts noe uA PN eee ae Bearer 792

» EVES RENE) a 2 oe gy eg aE gi go a Per SU OR ae f

PrPeMbes: aray and TEGGdISh. PPOWINS «cc. sie wees ol ue sise'e wre wee ese ee ees 264

SIPEG MCL Tee ies CTI Ve) ame N06 Wa) Ss 2) 0 ee en i |

Arelice (Ca lens), 20 teet- approximately... 6.5... e6s ec ccemen nes 396

males red and purple (bottom bed)... 0.26. eee ee ee eee ee f

Probably little faulting.

DOSE Ts 5 ESE iy Goer Pt Boies Se i Ae |e Rea A Sn 1452

&. This part of the area shows occasional outcrops of gray and red argillites

for a distance of ten miles northeast of Princeton. The northward ex-

tension of this series is hidden beneath the Cretaceous cover.

The accompanying map of the Lockatong formation (Plate VII)

shows its actual extent, and the locations of the sections above described.

PALEONTOLOGY

Fossil remains are far from rare in the area of the Triassic rocks. At

various horizons, from the bottom to the top of the series, records of

animal and plant life have been found. In general, these remains occur

scattered through the occasional strata of the rocks that possess dark

colors, and also often in the light-colored arkosic strata (plants) and in

the shales associated with the latter. Mud-cracks, ripple marks, and the

footprints of animals have been repeatedly found, the latter most fre-

quently in red shales or sandstones.

The Lockatong is composed essentially of rocks embracing a variety of

darker or lighter shades of gray, and, following the general rule, it pos-

sesses a considerable fossil content, particularly in those layers which are

darkest. The fossils become increasingly numerous and well preserved

152 ANNALS NEW YORK ACADEMY OF SCIENCES

toward the southwest, the best locality for them being the vicinity of

Pheenixville, Pa., particularly the Reading Railroad tunnel at that place,

now largely inaccessible. A detailed list of the fossils from this locality,

as originally published by Wheatley, is given below.

The fossils are more frequent in the shaly layers than in the massive

ones. The collector in the field will usually find traces of fish scales and

crustaceans in the blackest shale layers. A few well preserved specimens

have been taken from the densest beds of gray argillite, as shown by the

eycad fronds obtained from Carversville, Montgomery Co., Pa.,* and the

splendid frond of a cycad, Otozamites latior (Saporta), found in one of

the Princeton quarries about 1884, and now on exhibition in the geo-

logical museum at Princeton University.

The most important fossils of the Lockatong are the following:

Seales of ganoid fishes, usually separated, but at times in groups in

black ‘shale layers. Rhomboidal, enamelled scales, either smooth and

without ornamentation (Semionotus (sp?)) or ornamented with a pat-

tern of deep furrows and ridges (Ptycholepis (sp?)). One maxillary

of Semionotus was found, together with scales and head parts of this

fish, in a limy layer near Wycombe, Bucks Co., Pa.

Estherta. Shells of a phyllopod crustacean. Longest diameter about

half a centimeter, usually appearing as flattened disks on the surfaces of

black shale. The shells are ornamented with numerous concentric rings,

between which in some cases can be seen the “reticulate interspaces” de-

scribed by T. Rupert Jones. These are abundant in some layers in the

southwestern part of the area, as at Phoenixville, and are usually asso-

ciated with ostracods (Candona rogerst; see description in Jones’s mono-

graph). Most of the crustaceans found are Hstheria ovata. Other spe-

cies of Hstheria have been reported by C. M. Wheatley, T. R. Jones and

T. A. Conrad. Among the specimens collected by the writer, the species

EF. ovata only has been identified. Some tiny shells found at one locality

are doubtless the same form in an early stage of development. With the

estheriz and ostracods the scales of Semionotus often appear, as at

Wycombe. |

Certain layers of shale are found to carry numerous microscopic black

spines, which do not correspond with those of the ganoid fishes or with

those of echinoderms. They may be the sete or parapodia of the worms

whose borings are often seen in the sandy layers. They are, however, too

small for positive identification.

Cycad fronds occur rarely, as described above.

7 Brown, A. P., “New Cyads and Conifers from the Trias of Pennsylvania,” Proc.

Acad. Nat. Sci. Phila. for 1911, pp. 17-21.

‘A Monograph of the Fossil Estherie, Paleont. Soc. Lon., 1862.

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC | 153

Of the fossiliferous portions of the Lockatong, the Reading Railroad

tunnel at Pheenixville is probably the most prolific.® This locality has

afforded estheriz, ostracods, plant remains, coprolites and various mam-

malan remains, including many bones and teeth. Wheatley reported

certain strata full of Saurian bones, and some layers filled with teeth.

Certain reddish brown layers were also found to contain abundant carbon

derived from organic remains. The species of fossils from this tunnel at

Pheenixville are to be fully described in the Honeybrook-Phcenixville

Folio of the United States Geological Survey, soon to be published. One

of the horizons where specimens of Hstheria ovata abound is now exposed

near the southern portal of the tunnel, where in the black shales they

may be found in large numbers and in a good state of preservation.’°

The following species from this locality were listed by Wheatley in

1861:

PLANTS

Equisetum columnare Brong.

Pterozamites longifolius Emmons.

Gymnocaulus alternatus Emmons.

Fir-cones.

Calamites punctatus ? Emmons.

Plants, seed vessels, etc., genera undetermined.

CRUSTACEANS

Estheria ovata (Posidonia ovata Lea.)

Estheria parva (Posidonia parva Lea.)

Cypris.

Limulus ?

FISHES

Turseodus acutus Leidy.

Radiolepis speciosus Emmons.

Catopteris gracilis Redfield.

REPTILIANS

Clepsisaurus Pennsylvanicus Lea.

Eurydorus serridens Leidy.

Composaurus — ? Leidy.

Centemodon sulcatus Lea.

Bones and teeth probably batrachian.

Coprolites.

Foot-tracks.

® WHEATLEY, €. M., Amer. Jour. Sci. and Arts, Vol. XXXII, p. 45, 1861.

10 Tbid., pp. 45-46.

154 ANNALS NEW YORK ACADEMY OF SCIENCES

The canal quarry, situated about a mile north of Phoenixville, on the

Schuylkill River, yields ganoid scales and plant stems. Some three or

four miles farther east, there is a good exposure along the Perkiomen

Railroad; north of Oaks station, near the road bridge which crosses the

railroad cut, the black shales are filled with estheriz, with a few fish re-

mains. The next exposure farther northeast is the cut of the Philadel-

phia and Reading Railroad between Gwynedd Valley and North Wales.

From this locality some few fish scales and possibly estheriz have been

reported. Near Wycombe station, on the North Pennsylvania branch of

the same railroad, there is a limy layer carrying estheriz and fish scales,

with ostracods. This layer weathers yellow, and is best shown in a small

quarry along the railroad, some 1000 feet south of the station.

Many years ago, F. L. Nason’ found estheriz at Scudders Falls, on

the Delaware River, and fish scales have been reported from this vicinity

(Washington’s Crossing). Scudder’s quarry, one and one-half miles

north of Lawrenceville, contains some good scales of both Semionotus

and Ptycholepis, as well as a wealth of tiny black spines or sete. All

these are in the black shales in the center of the quarry, and all occur

practically together.1? Other exposures examined by the writer yielded

little except a few obscure plant remains and tiny spines.

Fishes of the Semionotus type have been found at many horizons in

the Triassic rocks of the New Jersey-Pennsylvania area, as well as in the

Massachusetts-Connecticut area. Good specimens have been found in

the lower part of the Stockton series below the Palisade trap sill at Wee-

hawken; there are specimens of a similar fish from excavations near

Plainfield, N. J. (Warrenville copper mine), in the center of the Bruns-

wick; and the large numbers of splendidly preserved examples from

Boonton, Morris Co., N. J., near the top of the Brunswick, are well

known. Sunderland, Mass., and neighboring places are also notable as

localities for fossil fishes. Of these fish-bearing horizons the Lockatong

is but one, and not the principal one. ‘The presence of fish remains

throughout the Newark series speaks clearly of roughly similar condi-

tions reappearing at intervals during the time of deposition; and the

presence of these remains throughout the Lockatong emphasizes its har-

mony and unity with the rest of the larger series. A full description of

the fossil fishes of this type is given in the Annual Report of the State

Geologist of New Jersey, 1904, and more recently by Chas. R. Eastman.%8

11 Ann. Rept. State Geologist of N. J., 1888, p. 29.

Spee op. cit., p. 88, makes an evident reference to this focalite.

“Triassic Fossil Fishes of Connecticut,’’ Conn. Geol. Surv., Bull. 18. 1911.

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 155

PETROGRAPHY AND CHEMISTRY

Under the microscope, little can be determined regarding these rocks,

except by the use of high-power objectives. The most typical argillite of

the densest type appears to be composed mainly of tiny quartz grains of

an extremely angular shape, together with a few bleached biotites, and,

at times, a little feldspar. In some cases, the feldspars become much

more numerous; some of them show well developed plagioclase twinning

in wide bands, although the majority are orthoclase. The feldspars are

angular cleavage fragments, and appear for the most part perfectly fresh.

They are evidently primary constituents, as also the biotite appears to be.

The biotite is in small lath-shaped fragments, pale brown in color, show-

ing traces of parallel cleavage and high order interference colors, high

relief and parallel extinction. The whole aggregate resembles closely an

assemblage of the constituents of some of the gneisses from whose disin-

tegration products the Triassic rocks were undoubtedly derived.

At Byram, Hunterdon Co., N. J., there is a large active quarry in the

dense massive layers of the Lockatong. At this locality, as Professor

J. V. Lewis** has pointed out, the rock is much indurated on account of

the proximity of a diabase sill of considerable size and extent. Micro-

scopic investigation of the quarry rock shows that its ground-mass is

thoroughly re-crystallized, giving to it an almost flinty hardness, so that

it rings when struck with the hammer. The sediments close to the dike

are re-crystallized also, and in them there are biotites and hornblendes

which seem to have been produced in situ, with some areas which appear

to be scapolite, as originally described in the publication above noted.

The rock at this place is a true hornfels. The effects of the diabase, how-

ever, die out within a few hundred feet of it, and such biotites and feld-

spars as are found in the rocks far removed from igneous action appear

to be purely clastic.

The Lockatong series is for the most part free from visible igneous

rocks, though it is to be noted that a number of narrow dikes appear.

The Lockatong strata in general do not strongly resemble those which

have been “baked” by the intrusives, although the derivation of the silica

cement, described below, from hot solutions emanating from the intru-

sives does not seem impossible. The color of the various strata, however,

is easily accounted for, with the help of the chemical data at hand, with-

out appealing to igneous action. The reddish and gray phases of the

massive argillites are very much alike in every way except color. A

massive gray layer is often seen to change upward or downward to a red-

14 Ann. Rept. State Geol. N. J., 1908, p. 95.

156 ANNALS NEW YORK ACADEMY OF SCIENCES

dish brown color, the transition taking place within a thickness of two

inches or less, the texture and general appearance of the rock suffering

no alteration otherwise. ‘he percentages of silica and total iron in two

specimens of the building stone, red and gray, from horizons twenty feet

apart in the Princeton quarries, are almost identical :

Massive red argillite, SiO,, 46.40 per cent. Total iron, 6.05 per cent.

Massive gray argillite, Si0,, 46.42 per cent. ‘Total iron, 5.61 per cent.

A content of seven or eight per cent of total iron seems to be normal for

these rocks, and some such amount usually appears in the analyses. Thus

it is with the following series of analyses:

Determinations of Iron in Lockatong Argillites

Sample FeO Fe,O, Total Fe

Per cent Per cent Per cent

sR on wire ee eae Rens ALE Bien ik eae 3.00 7.80 8.28

Drie bh So atie Signs AR cane ee aie rae 3.65 7.88 8.40

eo eva aaank valiaue Camila miele ice RUMa eT ha eer nae Ema Le aG 9.38 (50)

A 8 cic abs tate Cane ER a arse EL atop eee GRRE 4.40 3.81 6.10

Davis, oh eta tous ane eitshalte Mattes x ach Uanerebeaar ane eens ra 5) 4.52 8.77

Ged, ee oe o heft es tole eT 9.30 0.91 7.91

(WO Ra Rian Sem oe ae A Ne Ware YA mA A eo 5.12 4.97 7.50

By PE Ocal te cde k aes eee EN Peachey mee 5.65 3.07 7.98

Red Argillite Samples:

1. McCarthy’s Quarry. Princeton, bottom of quarry wall.

2. McCarthy’s Quarry, Princeton, middle of quarry wall.

3. McCarthy’s Quarry, Princeton, top of quarry wall.

Gray Argillite Samples:

4. McCarthy’s Quarry, Princeton, middle of quarry wall.

5. McCarthy’s Quarry, Princeton, top of quarry wall.

6. Shanley’s Quarry, Byram. Analysis by R. B. Gage.

7. Scudders Falls, Traction Company’s quarry, bottom of quarry wall.

Olive Green Argillite:

8. Scudders Falls, Traction Company’s quarry.

Qn each of the above, duplicate determinations closely agree.

The percentage of Fe,O, is in every case much higher in the red rocks

than in the gray ones. This indicates that the color of the red layers is

due to the presence of hematite, while that of the gray layers is partly or

wholly due to ferrous iron. This is in accordance with the work of

Spring, who obtained results of a similar nature from the study of red

and gray sediments of Devonian age.

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 15%

Certain limestone layers that are occasionally developed to a thickness

of one or two inches, which appear light gray and coarsely crystalline on

the fresh fracture, but which rust on weathering, contain, on the aver-

age, nine per cent of MgO. They are therefore not true dolomites, but

should be called magnesian limestones.

The color of all the blackest shales of this formation is due to carbon,

which burns off from the powdered sample, heated in a crucible nearly to

redness, usually leaving the sample gray in color, The origin of the

carbon is in the organic remains, of which traces can usually be found

somewhere in such beds. Part of the color of the massive gray layers is

due to the same cause.

The iron compound in the argillite is not the cementing material,

since, if boiled in concentrated hydrochloric acid for some time, the rocks

lose the color from their surface, but the interior of the mass does not

disintegrate in the smallest degree. Under similar treatment both the

red and the gray rocks of the type referred to behave similarly.

The cement of the strongest and most compact of the massive argil-

lites (those described above, for instance) is opaline silica. The slow

maceration of a small solid sample of the rock in a concentrated solution

of sodium hydroxide on the water bath, for from 36 to 48 hours, reduces

a considerable part of it to slimy mud.*®° The opaline cement was ob-

served some years ago in sections of the rocks by Professor J. V. Lewis.*®

The rocks of this series are, however, of a widely varied character, some

layers showing a more calcareous cement, and others having very thin

limy layers intercalated with siliceous ones.

Some of the feldspar fragments observed in this rock under the micro-

scope have cloudy or kaolinized borders, and doubtless much finer feld-

spathic material originally present has disappeared in this way. Kaolin-

ization of feldspars always sets free silica (Clarke). This silica is in a

condition to be readily taken into solution by waters of any kind. In this

dissolved condition the silica may be imagined to have existed in the still

moist muds of the Lockatong. From these solutions the silica would then

be deposited as the muds dried. Thus its introduction might be sup-

posed to have taken place contemporaneously with the deposition of the

sediments. If, on the other hand, the cementation occurred in the sedi-

ments sooner or later after their deposition, the silica might have been

introduced at a late period, as some observers have believed, in connection

with the great outburst of igneous activity which marked: the latter part

15 SPRING, W. Ueber die eisenhaltigen Farbstoffe sedimentirer Erdboden und iiber

den wahrscheinlichen Ursprung der rothen Felsen. Neues Jahrb. fiir Min., Geol. u.

Paleont. Jahrg., 1899, p. 47.

16 Ann. Rept. State Geol. N. J., 1908, p. 95.

158 ANNALS NEW YORK ACADEMY OF SCIENCES

of Triassic time in this immediate neighborhood. The strata lying be-

tween the Lockatong exposures and the nearest visible diabase sill show,

however, only occasional horizons of unusual hardness; they are not as a

whole much indurated. It further appears that the silica cement was not

generally distributed in the vicinity of the diabase sill; and buried in-

trusives beneath the Lockatong are improbable. For these reasons, the

writer favors the idea of cementation after deposition, but independently

of the igneous intrusions.

This siliceous cement is evidently a widespread and typical feature of

the Lockatong rocks, extending through many hundreds of feet of the

formation and throughout nearly all of the seventy miles of its exposed

length. It is also to be observed that the strongest rocks, massive argil-

lites whose unusual strength is dependent largely upon this cement, are

usually near the central part of the formation, both vertically and hori-

zontally, occupying the middle of the lens.

The existence of the clay soil of the Lockatong belt is doubtless one

very Important reason why most of the early investigators of the argil-

lites described them as clay rocks, largely composed of kaolin or similar

substances. Our present studies, however, would rather lead us to be-

heve that the kaolin, although really present in the soil, is derived, in

large part at least, from the alteration of feldspars which exist in the

rock in a fresh condition.

ORIGIN

The general shape of the Lockatong as a whole, and its sediments of

such exceedingly fine grain and of such uniform texture, give evidence:

of its mode of origin. Its present outcrop (Plate VII), and the com-

parison of detailed sections (Fig. 1, p. 149), indicate a lens-like shape,

with the finest sediments in the center of the lens, as might be true of a.

series of sediments filling a basin. The densest and most massive rocks

of the series, the argillites, are remarkably uniform in character, being

of very even grain and without coarse layers through thicknesses which

may be great, as at Byram, where a single bed is forty feet thick, without

a well marked parting along any of the bedding planes. Through a thick-.

ness of 3000 feet of beds in the Lockatong, there is scarcely a rock ex-

posed whose grains are large enough to be visible to the unaided eye.

Sedimentation during the time when these materials were deposited must:

have been very regular, and the conditions very steady and uniform for a

long period. The presence of crustaceans and of ganoid fishes points:

clearly to the existence, at times, of considerable bodies of water or tem-

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 159

porary lakes. A region of freshly deposited, unconsolidated muds, on

which lakes could exist for any length of time, must have had a level

surface throughout its extent, or else drainage would have been developed

and the lakes would have been quickly destroyed. The region may have

stood but little above sea level, or, what is more likely, a ridge of harder

rocks, perhaps some distance away, blocked drainage at the outlet of the

basin. The estheriz and ostracods are known to be fresh water, or pos-

sibly brackish water, forms. Hence the waters in which the Triassic

fishes thrived during the same period must have been fresh, or possibly

brackish, as the fish scales are found with the other forms mentioned, at

Wycombe and elsewhere, This would appear to have some bearing on the

problem of the state of the waters in which the same species of fishes

lived, at Boonton and Sunderland. The aspect of the whole body of the

Lockatong sediments is that of a mass of fine-grained muds, carried down

from the higher crystalline uplands surrounding a structural trough,

which had been but incompletely filled by the quickly accumulated sedi-

ments of the Stockton series. The continued filling-in by these fine

materials formed a mud-flat upon which pools of water (playa lakes)

gathered, and in time dried up again, leaving large numbers of well

formed sun-cracks, and occasional ripple-marked layers, together with

the remains of living forms, above described.

The thin limestone layers encountered at and near Princeton may have

been deposited as a chemical precipitate, or may be the product of cal-

careous animal remains. No fossils were found in these layers. It has

been suggested that this limestone might be similar in origin to the desert

limestone crusts of Africa and the Bad Lands, which are produced by the

evaporation of ground waters brought to the surface by capillary attrac-

tion. The Lockatong lmestones, however, occur in the midst of black

shales which usually carry organic remains. Other thin limestones, which

contain abundant FHstheria shells and fragments, may have been formed

by solution of the Hstheria shells themselves.

Throughout the study of these rocks, nothing has been found in them

that would in any measure offer proof of a volcanic origin. No coarse

material resembling bombs are to be seen in the field, and no trace of

anything resembling volcanic ash was observed in the thin sections. In

Connecticut, abundant volcanic deposits of the above sorts have been

noted in the Trias and described by Emerson and by Davis, but there ap-

pears to be a scarcity of such phenomena in the New Jersey-Pennsylvania

area. ‘There seems to have been no volcanic activity in this latter sec-

tion until long after the Lockatong sediments were deposited and buried

under an accumulation of perhaps several thousand feet of the overlying

160 ANNALS NEW YORK ACADEMY OF SCIENCES

Brunswick beds. What appear to have been the first eruptions in this

vicinity took the form of surface flows, the principal members of which

now form the Watchung ranges in New Jersey. (See Annual Report of

the State Geologist of New Jersey, 1897, Plate III, p. 32.) Even were

we to suppose the intrusive diabase of the Palisade-Rocky Hill sill to be

earlier than the extrusives, yet, since it cuts through the Lockatong

series, it is younger than that series, and could not have furnished ma-

terial for it. Moreover, an intrusive sill could not form ash. ‘There

seems no good reason to expect the occurrence of deposits of volcanic ash

before the time of the Watchung flows, although, of course, volcanic ash

is often carried for considerable distances by the wind. The petrographic

evidence, however, is strongly opposed to such a constitution.

It has been suggested that the Lockatong may represent the finest rock

flour of re-worked glacial deposits. While there is no direct evidence

favoring this latter supposition with regard to Lockatong deposition, still

such an origin may be regarded as a possible one. However, no glacial

markings have been observed among the coarse pebble beds of the under-

lying Stockton formation, nor have they ever been reported elsewhere in

the local Triassic. For physiographic reasons also, as explained below,

this hypothesis seems rather unsuitable to the case in hand. The numer-

ous investigators of the Triassic formation, both here and abroad, have

repeatedly emphasized the possible derivation of the Triassic sediments

from rocks which were undergoing the normal process of weathering in

warm. humid climates.

The most typical portion of the Lockatong is the central mass of argil-

lites. The central portion of the lens is at its maximum more than 2000

feet in thickness, and is prevailingly gray in color, as it is in the large

exposures at Byram. Above this central portion, red, sandy beds begin to

appear at intervals, intercalated with a series of dense gray beds of typi-

cal Lockatong aspect. Farther upward the gray beds become less and less

numerous, and in time cease altogether, when the Lockatong passes into

the typical red sandy shales of the Brunswick formation above. These

“transition beds,” as they are called, are usually several hundred feet in

thickness. Below the argillites, the same conditions appear. The upper

part of the underlying Stockton series is usually red shale. These red

shale beds may be developed to great thickness, as at Raven Rock, N. J.,

some two miles south of Byram, where they form a cliff high above the

river. Above the red shale the dense gray rocks appear, at first only oc-

casionally, and in two-foot layers, then gradually crowding out the red

beds, until the whole series is dense and gray. The transition beds are

marked by large areas of mud-cracks and ripple marks, and are especially

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 161

well exposed along the valley of Lockatong Creek, Hunterdon Co., N. J.,

which is the type section.

N. H. Darton and H. B. Kiimmel, in their reports accompanying the

recent geologic folios (Trenton and Philadelphia Folios), repeatedly

emphasize the presence of wide transition zones on the borders of the

Lockatong. For instance, on pages 7 and 8 of the Philadelphia Folio,

Darton says:

“These three formations (the Stockton, Lockatong, and Brunswick) are not

sharply separated by abrupt changes of materials, but usually merge through

beds of passage which appear to vary somewhat in thickness and possibly also

in stratigraphic position in different areas.”

Poor definition of the boundaries of the Lockatong series is typical on

account of the pronounced interdigitation with the formations above and

below, which has been the cause of some uncertainty in mapping those

boundaries. Its boundaries are rarely if ever definite planes, but are

zones of transition from one formation to the other, by alternation of

beds. It seems plain, therefore, that a portion of the Lockatong beds

‘that lie along its lower margin are really as closely related to the Stock-

ton formation as to the Lockatong, while several hundred feet of beds,

more or less, in its upper portion, might just as reasonably be classed

with the Brunswick. The presence of abundant ripple marks and mud-

cracks in the transition beds, as at Lockatong Creek, emphasize the evi-

dence of rapidly varying conditions. Along the strike the Lockatong

seems to pass into the other sediments, its typical argillites being there

represented by rocks of a different nature. The conclusion of H. B.

Kiimmel,’? with regard to that portion of the Lockatong series which

occurs in New Jersey, would therefore appear to be equally true of the

area of Lockatong rocks as a whole. In discussing the absence of the

argillites in the general area north of Princeton, he says:

“The most probable explanation for the absence of these beds is, therefore,

that the conditions favoring their formation did not prevail in the northern

part of the basin; that here the red shales and sandstones were deposited con-

temporaneously with the argillites and flagstones of the southwest, and that,

could we trace the latter from the point near Princeton, where they begin to

disappear beneath the Pensauken and Cretaceous deposits, we would find all

the steps in their transition to the soft red shales. It follows from this that

the term Lockatong, when used apart from the particular rocks to which it was

first applied, represents certain conditions of sedimentation, which resulted in

the deposition of hard shales, flags, and argillites, and not a definite time-

period.”

7 Ann. Rept. State Geol. N. J., 1897, p. 41.

162 ANNALS NEW YORK ACADEMY OF SCIENCES

For the movement of such fine materials, but little power on the part

of transporting agents would be required. It may have been, in part, the

work of wind, even though no direct zolian deposits have been observed

among the sediments, and thus, as far as present evidence goes, water

was the final agent of deposition. The Lockatong sediments were origi-

nally very fine muds, which would remain suspended in water a long time

before settling, doing so only when the waters became very quiet, or

where the moisture dried up. Everything points to the hypothesis that

drainage was far from active in the region of Lockatong deposition.

The Stockton beds represent large quantities of bowldery gravels, full of

fresh feldspars, distributed over a wide area which must have been covered

with abundant standing water, in which the deltas spread out from the

shores of the basin toward its center. The Lockatong deposition appears

to have been accomplished under a continuation of these conditions. The

results were much the same, except that the later sediments were of the

finest type, being muds instead of pebble beds. The change in the depo-

sition must have been due to a weakening of the streams, probably on

account of degradation of the highlands by normal erosion. 'The torren-

tial periods of the Stockton gradually ceased, although they appear to

have persisted for some time in decreasing strength on the borders of the

basin. We may imagine that the fine muds of the Lockatong drifted in

and filled up the deeper portions of the basin, which were not already

occupied by the rather poorly distributed deltas of the Stockton. Ac-

cording to this arrangement, the Lockatong beds would naturally collect

in the central part of the basin, and might contain much re-worked ma-

terial from the Stockton along the shores, as well as detrital materials

coming directly from the older rocks. What sort of material occupied

the east and west sides of the Lockatong trough cannot now be deter-

mined, as the eastern border has been removed by erosion and the western

is buried under the Brunswick series. ‘To the north and south the beds

are apparently replaced by the Brunswick and perhaps the Stockton.

Whether, during a portion of the time of Lockatong deposition, erosion

was actually taking place elsewhere upon the Triassic sediments, is not

plain. If this were true, an erosion interval should be indicated between

the Stockton and the Brunswick beds to the north and south; in New

Jersey, this contact is hidden beneath later deposits, and even in Penn-

sylvania, the same condition seems to obtain, although the actual rela-

tions are not well known. After the close of the Lockatong deposition,

the coarse sediments gradually reappeared, giving rise to sandy shales and

sandstones. This increased coarseness of sediments shows a renewal of

erosional activity which strongly suggests the beginning of an erosion

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 168

cycle. Hence it is suggested that the Lockatong may mark the close of

the erosion cycle which was begun when the Stockton beds were deposited,

and that the Brunswick may indicate the beginning of a second cycle,

probably brought about by a slight upward warping of some of the land

surrounding the basin, which cycle continued through Brunswick time.

CRYSTAL GROWTHS

Much of the Lockatong argillite, even in its densest phases, is charged

with disseminated specks of crystalline calcite, usually minute in size.

This calcite occurs as often in the red rocks as in the gray, and is prob-

ably a secondary filling in spaces from which some earlier material has

been leached. It often follows the course of a horizontal stratum, and

does not favor the joints.

Apart from the foregoing, there are other growths of a somewhat simi-

lar nature, but of more limited distribution, which, on detailed examina-

tion, are found to exhibit certain systematic peculiarities that suggest a

somewhat more complicated mode of origin. ‘These are curious fan-

shaped radiations of white material, which appear most plainly in the

quarries at the east end of Princeton, being at times quite conspicuous

features. The arrangement, where most typically exposed, is as follows:

Filling one stratum, perhaps two feet thick, are sharply defined, slightly

tapering lines of white material, which originate at a common horizon

defined with great clearness. The white stringers diverge downward

from this horizon in slightly curving lines, meeting at the top in points

which are definitely spaced, according to the amount of development of

the whole. Vertical cross sections of these radiations in different direc-

tions, as well as vertical sections of the same portions at right angles to

each other, afforded by the corners of joint blocks, show that what we

really have is a series of conical arrangements, composed of strings of

crystals which radiate downward always. Above the layer of conical de-

velopment there is usually a zone of a foot or less containing white crystal

grains in irregular arrangement, as if considerably disturbed.

Thin sections of these crystals under the microscope show that these

are indeed crystal cavities, the appearance of regular outlines in the hand

specimen being amply borne out by the appearance in the sections. The

cavities at times show very definite angles which outline a form that

appears to be of a monoclinic or triclinic type.

In these exposures, the crystal groups follow definite horizons in argil-

lites which are gray, while at Scudders Falls (Traction Company’s

quarry, on the Pennsylvania side of the Delaware River) one massive

stratum with a strong reddish brown color shows a typical development

164 ANNALS NEW YORK ACADEMY OF SCIENCES

of the same arrangement, although it is not so well developed as in the

Princeton quarries.

It is evident that the material now filling these cavities is not original.

This filling is composed of an outer lining of isotropic analcite, which

has coated the walls of each cavity with free crystals whose outlines

plainly show, and calcite, which has filled in the balance of the cavity.

It appears that the entire rock mass has been soaked through and through

with solutions bearing the same minerals, which are found in excellent

development in the larger cavities of the joints. These solutions, as else-

where demonstrated, had their origin with the intrusive rocks not far

distant.

The exact nature of the original mineral that grew here in the Locka-

tong muds could not be determined from the material available. Some

of the crystal cavities occupy positions within the fillings of mud-cracked

layers, showing that they grew after the filling of the cracks by deposition

of another layer of sediment above. The whole system of conical crystal

growths is most unusual. Its similarity to the well known cone-in-cone

structure seems only apparent. There is no tendency in the argillites of

the Lockatong to break along the lines of crystals; breakage takes place

across the cones, along the bedding, showing the crystals following a pat-

tern of wavy lines within the cone. A thin section of cone-in-cone lime-

stone from Erie, Pa., showed no traces of crystal growths along the lines

of parting, whose production appears to have been due to pressure alone.

Possibly the growths in the Lockatong followed cracks which had been

produced by pressure ; but it is hard to explain by this method the growth

of isolated cones at regular intervals, whose production would require

isolated points of intense pressure, similarly spaced. It is more likely

that the original mineral was something similar to gypsum, which in its

crystallization often follows a radiating habit, and which grew in the mud

before induration.

Evidently the animals and plants of Lockatong time, carbon from

whose remains so often causes dark colors in these rocks, existed in the

general region where they are now found, since ganoid scales in certain

localities, as at Phoenixville, are still clinging tightly together. Plants

require some moisture, and estheriz still more, while fish remains indi-

cate considerable bodies of water—playa lakes—of some extent. Dark

shales of this character, found in the proximity of limestone layers and

carrying fish scales and estherizw, never have been observed to show mud-

cracks, a fact which would indicate that the sediments were constantly

covered with water and out of contact with the air. The passage into

gray argillites above, in which there is only a trace of carbon, and thence

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 165

into the red argillites, where there are neither carbon nor fossils, would

presumably indicate a gradual decrease in the amount of water present.

The growth of crystals within the sediments would seemingly require the

presence of a certain amount of moisture, although the quantity of water

may have been slight.

Jones,’® in describing the English estherie in particular, says:

“The recent estheris are found in fresh water, rarely in brackish water.

Guided by this fact, and taking for granted that our fossils were true estheriz,

and that estherie always have had fresh-water habitats, we should suppose

that the deposits in which these fossils are found, free from any appearance of

having been drifted, must have been formed in rivers, lakes, or lagoons.

The recent estherize appear, as it were, suddenly, in pools and ditches of rain-

water, and are quickly developed in tanks or ponds dry even ten or eleven

months of the year. . . . At all events, there is no necessity for supposing

them to have been marine; but where they occur by themselves, or in company

only of fishes and plants (the association of remains of land-plants with the

estherie is of frequent occurrence), they may be regarded as having lived and

died in fresh (or possibly brackish) water.”

All this goes to show that the waters where the estherie lived during

Lockatong time were not the waters of the sea, but were rather those of

inland playa lakes, such as have been described. Under these conditions,

part of the sediments were deposited where there was much organic mat-

ter. The carbon present, under the prevailing conditions of moisture

and soft sediments, speedily reduced the iron in those sediments to a low

state of oxidation, and the color of the mud became gray. Certain strata

of greenish argillites, whose color, as shown by chemical means, seems to be

due to iron silicate, occur at Ewing, Scudders Falls and elsewhere. These

layers are seamed with ramifying stringers of red mud which extend

downward from an overlying red bed for two feet or so into the green

sediments. This red material is evidently mud which has descended from

above, filling deep mud-cracks in the earler material. The fact that such

exceedingly deep mud-cracks could form and remain open in these green

muds shows that they must have remained damp throughout for a long

time. This agrees with our hypothesis that organic matter in the moist

sediments had time to reduce the iron in them. Mud-cracks are common

in the red argillite layers in places, but so far as the writer has observed,

they never appear deep. This shows that the red mud had an opportu-

nity to dry quickly, and under such conditions any organic matter present

was oxidized and disappeared, so that iron in the ferric state remained,

giving a red color to the rock. The small residue of carbon remaining in

the gray layers is the macerated remnant left after the reduction of the

iron.

4 Op. cit., pp. 7-8.

166 ANNALS NEW YORK ACADEMY OF SCIENCES

Chas. M. Wheatley, in his studies at the Phoenixville tunnel in 1861,

observed this phenomenon, which has been found te be very common

throughout the extent of the Lockatong rocks. In the tunnel he found

“olive green shale, with red veins,’ and above it, “red shale.” Red

stringers in olive green rocks, or angular fragments of the green material

in a reddish matrix, are often in evidence. Red fragments in a green

matrix, or green filling in red rocks, has not been observed by the writer,

although such a phenomenon is recorded by Dr. Kiimmel.’®

TECTONICS

There are, in the Lockatong rocks, three principal directions of frac-

ture. The first of these marks the lines of original bedding in the strata,

and along this series, except in a few cases, little movement has taken

place. The major joint series, which is strongly developed, causes a sepa-

ration along parallel plane surfaces nearly at right angles to the bedding.

There is also a parting at right angles to the other directions named.

The blocks resulting from fracture in these three directions are rectangu-

lar in shape, serving most admirably the purposes of building construc-

tion. Such fracture as is here described is perhaps best shown in the

“flagstone” layers of the formation.

The major joint series strikes usually forty degrees, more or less, east

of north. These are usually vertical, clean-cut joints. At an angle of

about twenty degrees to the major joint series there is a minor series of

joints, striking, in the Princeton area, from due north to north forty de-

grees east. This series has a dip of seventy-five degrees toward the east

in the case cited. It can be seen on a large scale in Shanley’s quarry at

Byram, ‘Two joint series at a relatively small angle to each other may be

explained by the theory of “rotational strain,’ as put forward by C. K.

Leith.?° At times an incipient slaty cleavage occurs, having a diagonal

direction, and causing the argillites and shales to develop deeply fluted

surfaces of parting along joint planes.

Nothing has been seen either in the rock sections or in chemical work

on solid chips, which would indicate any important arrangement of the

exceedingly small grains, save in the direction of the bedding. Therefore

it appears that the direction of the major joint series must be independ-

ent of the smaller structures of the rock itself, 7. ¢., that the cause of its

direction must be looked for without.

Along the major joint: series there has been some movement. This has

12 Ann. Rept. State Geol. N. J., 1896, p. 44.

20 “Rock Cleavage,” U. S. Geological Survey, Bull. 239, p. 112. 1905.

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 167

taken place in a horizontal direction, being in the nature of a shove or

heave without much deviation from horizontality. Such movement has

been quite general throughout much of the formation. It appears to have

been the result of a tension which opened each crack with a twisting mo-

tion, often bending strips of one wall across the cavity without breaking.

This is much like the phenomenon which Dale** observed in Vermont,

and which he described in the Sixteenth Annual Report of the United

States Geological Survey. In some cases, as shown by the Princeton ex-

posures, the movement tore strips completely away from the rock walls,

and in others, crushed sections which were weak or exposed, forming tri-

angular areas of intense brecciation at points of intersection with the

older joint series which it crosses. The sharp brecciation would indicate

that the movement took place suddenly, after the rock had become thor-

oughly hardened, and within a distance of the ground surface not too

great to allow the rocks to be within the zone of fracture. Probably the

load above was relatively small. The angular fragments of argillites in

the breccias appear to be perfectly fresh and unaltered, even at the very

margins, when examined macroscopically or microscopically. The min-

erals surrounding the fragments, the earliest and most important of

which were ilmenite, brookite and analcite, must therefore have been

introduced soon after the formation of the breccia.

In some portions of the breccia, the fragments of rock appear to be

some distance apart from each other, many at first appearing as if they

might be entirely free from any point of contact with other breccia frag-

ments or with the walls of the fissure; that is, they appear to be sus-

pended in the vein filling. A systematic study of favorable portions of

the breccia, by observation of successive surfaces of a specimen ground

down on a lap, shows that the fragments are very irregular, and that each

rests against its neighbor at one or more points. This helps to show that

the solutions from which the minerals were deposited came in slowly,

while from them the minerals here found gradually crystallized. Francis

H. Butler,” in October, 1911, published an account of an investigation

of brecciated material, wherein somewhat similar methods were described.

Attention is especially called to Plate V, accompanying Mr. Butler’s

paper. The breccias which he has chosen, especially in Figures 12-15, are

identical in appearance with some of those from Princeton.

The.major joint series, as developed near Princeton, is very persistent

in strength and direction, being always approximately north forty de-

2. “Structural details of the Green Mountain region,” U. S. Geol. Surv. 16th Ann. Rept.,

p. 15. 1894-1895.

2“The brecciation of mineral veins.’’ Min. Mag., Vol. XVI, No. 74, October, 1911.

168 ANNALS NEW YORK ACADEMY OF SCIENCES

grees east, even at Byram. North of the Rocky Hill trap sill this joint

series appears, in the shales, and in the borders of the intrusive diabase,

but apparently not within its central portion, where the joints are curv-

ing and irregular. The lines of major jointing show a tendency toward

verticality, although they sometimes hade about ten degrees east. It is to

be noted that this vertical position has little significance, as the joints

have probably been tilted more or less since formation, Moreover, a

knowledge of the precise direction of this or any other joint series, as

pointed out by Leith, and of the direction in which its walls appear to

have moved during tension, does not fully inform us as to the real direc-

tion of the force which produced the tension. “It may not be certainly

determined what combination of stress and strain conditions have been

present throughout the development of a given cleavage, although the

relations of cleavage to the final total strain may be known,” as he re-

marks on page 113 of his bulletin. All that we can safely say, then, is

that the tension occurred in a northwest and southeast direction in this

part of the Lockatong belt. This tension acted in some cases from one

side of the joint series, and again from the other.

In explanation of the production of this major joint series in the

Lockatong formation, and of the minerals therein contained, the writer

advances the following hypothesis:

The occurrence of titanium minerals in the fillings of these joint fis-

sures is one of the most interesting and important features. Titanium,

while abundant in disseminated condition in many rocks, is seldom seg-

regated in one place. Brookite and ilmenite are found in our mineralized

zones, and while they are present only in small amount, are of very beau-

tiful development. Ilmenite has been found at Princeton, in tension

joints and breccias. Ilmenite of exactly the same habit and of closely

similar form has been found at Byram, occupying tension joints, demon-

strably similar in nature and method of production to those of the above

locality, and in this latter case only fifty feet from an intrusive diabase

sill, so close to the trap that its derivation from the latter would seem

certain, in view of large quantities of ilmenite which are known to form

part of the normal constitution of the trap, and of the analcite and other

zeolites in which the ilmenite is implanted. Ilmenite has also been dis-

covered close to the diabase at New Hope, Bucks Co., Pa. It is embedded

in tourmaline crystals in the baked hornfels above the trap, and some

much altered sandstone layers there are at times quite highly charged

with it.

The tourmalines in the hornfels were produced by the expulsion of bar'¢

acid solutions from the trap while it was crystallizing, as explained vy

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 169

Dr. E. T. Wherry.24 With the tourmaline, in some stage of its formation,

ilmenite crystals were produced, some of which are inside the tourmaline,

but most of them in shallow pits on its outer surface. There is good rea-

son for thinking that the diabase sill at Byram was produced by the same

igneous outburst which gave rise to the Palisade sill and its supposed ex-

tension, the diabase at New Hope. The Byram and New Hope ilmenites,

and also those at Princeton, are probably very nearly or quite contempora-

neous. At the time of the expulsion of the titanium from the trap, the

tension joints were formed by horizontal heave, as is shown by the By-

ram deposit in one of them. The trap also was affected by this move-

ment, and joints in the same direction were strongly developed on its

margins, but as the central part of the mass was perhaps still fluid, it

did not develop the same joint system, but curving joints appeared later,

which show only in a general way a tendency to take the same direction.

Several fault planes of similar nature in the Pennsylvania Triassic are

filled by diabase dikes, which shows that some fluid diabase was probably

present at that period. The ilmenite, analcite, etc., in these joints were

hence undoubtedly derived from the trap rocks in their cooling stages.

This system of joints is notably parallel to the Flemington-Hopewell

fault series. It is not, however, strictly of the same age, since the move-

ment of the above named faults has been strongly vertical, without any

known horizontal component. Such a fault as the Flemington-Hopewell

one, with a throw of 17,000 feet, indicates a disturbance of large dimen-

sions in the basement rocks below. The resulting strain effects upon the

Triassic must have been widespread and thoroughly distributed. This

faulting did not, of course, take place all at one time. The great Flem-

ington fault has probably been of very gradual production. Movement

along this line is evidently still taking place, as shown by the not infre-

quent earthquakes experienced in Doylestown. Probably the first indica-

tion of this movement was a little sagging under the center of the basin,

accompanied by the formation of a slight syncline in the later rocks

above. In the formation of this syncline, the lower layers of the Triassic

were stretched. The most brittle layers, among which were the Lockatong

beds, gave way first, and tension joints were formed. As the disturbance

increased, the movement was changed wholly to vertical, taking place

along a few major lines of fracture, represented by the Flemington and

Hopewell faults. The almost total freedom of the Lockatong formation

in Pennsylvania from vertical faults of any considerable magnitude is

*% “Contributions to the miner. Newark group of Pennsylvania.’”” Trans. Wag. Free

nst. Sci. of Philadelphia, Vol. VII, Feb., 1910.

170 ANNALS NEW YORK ACADEMY OF SCIENCES

attested to by the long exposures which show individual strata extending

for many hundreds of feet without interruption.

Such a hypothesis as the above would place the beginnings of the

Flemington-Hopewell fault series at a time immediately following the

intrusion of the Palisade-Rocky Hill diabase sill. Since this fault series

affects practically the highest horizons of the known Triassic in the New

Jersey-Pennsylvania section, this would place the intrusion of the Pali-

sade sill at a time about the close of the Triassic period of deposition here

represented, or perhaps a bit later.

The joint series which is at right angles to the principal series was of

earlier production, and must have been tightly closed and discontinuous,

since it contains none of the mineral deposits above described.

With the ilmenite and analcite in the major joints and brecciated zones

at Princeton, crystallized barite appears. A quantity of barite is present

at Glenmoore, near Hopewell, N. J., and another similar deposit exists at

the western end of Buckingham Mountain, in Bucks Co., Pa., where the

Flemington and Hopewell faults unite. In both of these localities the

barite occupies a breccia, being evidently typical of this series of fault

zones. Barite has been found in cavities of the Palisade diabase, at Ber-

gen Hill, N. J., in crystals two or three inches long and an inch thick.

Without doubt most of the local barite originated with the trap rocks, as

did the barite found with the ilmenite and analcite at Princeton. The

analysis, however, of R. B. Gage?’ shows that at least some of the Locka-

tong sedimentaries carry as much as 0.11 per cent of BaO. The circula-

tion of waters through such a rock might account for small occurrences

of barite.

Titanium minerals, such as the ilmenite and brookite which appear in

such good development, require heat for their artificial production. Little

is known, however, of their exact mode of formation in nature. Analcite

is commonly associated with the minerals of the trap rocks, although

under very special circumstances it may be produced in other ways; it

does not require excessive heat for its production. The finding of anal-

cite as a close associate of minerals derived directly from the trap while

cooling, has a possibly important bearing on the origin of analcite in

some other localities where it 1s associated with the trap rocks. The dis-

covery of analcite with “EHisenrosen” of ilmenite and well formed brookite

crystals, on joint planes of sedimentary rocks, having at first sight no

connection with igneous action, is a matter of much interest.

The Rocky Hill-Palisade diabase sill, although now much reduced by

erosion, must once have overlain much of the vicinity of Princeton. The

* Ann. Rept. State Geol. N. J., 1908, p. 96.

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 171

prevailing dip of fifteen or twenty degrees would carry the trap a mini-

mum distance of 1500 feet above the mineralized zone at Princeton. ‘The

most strongly and typically mineralized zone extends at intervals from

Princeton to Rushland, Pa., the whole of which area is flanked on the

north by an irregular diabase sill whose original extension may have been

2000 feet or so above the present exposed Lockatong. At the north end

of the formation, the Rocky Hill diabase extends up through it, and being

very irregular, may extend under it, or may be connected with a sill which

lies under it. The presence of small but persistent dikes to the south

attest to the presence there of at least some igneous activity. Brookite is,

moreover, seemingly authentically reported from Pheenixville.

Solutions that originated with the intrusive rocks of the ‘Triassic

usually travelled upward rather than downward. ‘This is shown to a great

extent in the region just northwest of New Brunswick, N. J., where the

shales are filled with frequent small copper deposits that have come up in

solution from the diabase below. Such solutions travelled upward be-

cause there were more open cracks and fissures above the intrusive than

below it. Large fissures such as fault zones, as at Menlo Park, furnished

channels along which solutions rose for thousands of feet. Mineralized

solutions were, however, abundantly present below the slowly cooling trap,

as well as above it.*° Ilmenite crystals have been noted in feldspar seams

just below the Palisade sill. In case a well developed series of open

cracks existed at the time of intrusion, or such a series were opened by

some widespread force acting before the intrusive had fully cooled, such

solutions might find their way a long distance downward. Unless such

action can be supposed in the vicinity of Princeton, we must look for the

origin of these mineral deposits in another intrusive at a lower horizon,

which would occupy a position beneath the Lockatong rocks of Princeton

and the region south for some distance. ‘The existence of such an intru-

sive, while possible, finds no proof in any evidence gathered in the field.

In some of the exposures, notably at Princeton and at Lawrenceville,

vertical joints are coated with a thin film of black bituminous matter.

This material resembles anthracite coal or one of the dense asphalts. Its

luster is bright and its fracture conchoidal. It has been derived from

disseminated organic matter of the black shales, and, circulating as liquid

or gaseous hydrocarbons, it has been deposited in the vertical joints,

which were the only available openings. Whether its concentration is

connected with the injection of the diabase is a question ; but as just such

bituminous matter is seen on vertical joints at many points throughout

the Newark series, any such connection is improbable.

*6 See reports of the State Geologist of New Jersey for 1906 and 1907.

172 ANNALS NEW YORK ACADEMY OF SCIENCES

MINERALOGY

A crystallographic study and discussion of the minerals found within

the boundaries of this formation has already been published by the

writer ;27 it serves as a summary of those species which, to the writer’s.

knowledge, have been found in this region, up to the spring of 1912.

This description applies particularly to the deposits lying between Prince-

ton and the Delaware River.

Most of the best exposures, where minerals are obtainable, are in quar-

ries now being operated, where the continued accessibility of these de-

posits is well assured, and new occurrences are almost certain to appear-

Most of the productive deposits are in seams'carrying analcite, but many

of the calcite seams also will be found to be interesting.

COMMERCIAL ASPECTS

Some criteria for testing a rock in order to determine its availability

for building material are given by Dr, Chas. P. Berkey in his report on

the Catskill Aqueduct (p. 199). Among these are the following:

Specific gravity.

Weight per cubic foot.

Porosity, in per cent.

Per cent water absorbed.

The tests here enumerated were tried upon samples of the Lockatong

argillites, with the following results:

The specific gravity of a specimen of the argillite from Princeton was

found to be 2.57. Hence the weight per cubic foot of the Princeton ma-

terial is 160.62 pounds. This agrees closely with the estimate of a con-

tractor using this stone in Princeton, and also with the weights of many

standard building stones in use at the present day.

A specimen of the hard reddish brown argillite from Matthews’s

quarry, Princeton, was ground to a nearly cubic shape, with smooth faces

about an inch square. This block was dried for 6 hours in an air bath at.

a temperature of 130° Centigrade. It was then removed, and immersed

in a beaker of distilled water, in which it was boiled for half an hour,

until no more air bubbles appeared on its surface. The surface of the

block was then dried off quickly, and upon weighing the sample was

found to have taken up .0014 per cent of its weight of water. This test

shows that the pore space of the argillite is exceedingly small, and that

the penetration of water into the rock is shght. The latter fact is well

27 Amer. Jour. Sci., 4th series, Vol. XXXV, pp. 446-450. 1913.

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 173

shown in the quarries, where rock that has been immersed in water for

long periods will be found upon breaking to be perfectly dry inside, with

the exception of an eighth of an inch next to the surface. The small

amount of pore space is caused by the extreme fineness of grain and by

the siliceous cement with which the rock 1s filled. Since water is unable

to gain access to the interior, the damage to the rock by frost is scarcely

perceptible. The effects of expansion and contraction with changes of

temperature are also slight.

The argillites will melt at about 1100° Centigrade. It is not safe,

therefore, to employ them for structural material in chimney linings or

in other places where they may be exposed to intense heat.

The argillite is evidently a very strong and resistant rock, and it has

successfully stood the test of the last one hundred years in such buildings

as were constructed of it. On account of its varied colors, the argillite

has been used with pleasing results in the construction of some of the

newer dormitories at Princeton University. It is being extensively em-

ployed in the new Graduate College connected with the university, and in

the new High School building at Princeton. Its use in concrete con-

struction has been extensive in the Graduate College; it seems to serve

the purpose well, except that the argillite fragments are sometimes too

smooth to offer a good surface for firm adhesion of the cement. There

seems to be no reason for believing that this rock is not as good as trap

rock for many of the purposes for which the latter is usually employed ;

the trap rock, moreover, often has the disadvantage of much greater

coarseness, and a corresponding degree of susceptibility to the destructive

action of the weather. The argillite, as a building material, should be

more widely known.

SUMMARY

The Lockatong formation is the middle member of the Newark series

of Triassic rocks, extending from a point just west of Phcenixville to the

vicinity of Princeton. |

The rocks constituting the formation are dense, fine-grained, massive

mud-rocks known as argillites, with some shales. The formation as a

whole has a decidedly lens-like character. The present investigations

have led us to believe that these sediments were laid down in an inland

basin, and probably in the center of that basin. This hypothesis is sup-

ported by the general structure as observed in the field, by the testimony

of the fossil estheriz, fish scales, ostracods and plant remains found

within its layers and by chemical studies. The color of the rocks is

largely due to iron in various states of oxidation, the presence of which

174 ANNALS NEW YORK ACADEMY OF SCIENCES

in these states is more probably the result of normal processes of depo-

sition than of alteration by igneous or other later action. The cement is

for the most part silica, the origin of which is by no means easily estab-

lished, but which does not seem to require abnormal processes or later

alteration for its introduction. Some horizons in the Princeton area con-

tain regularly arranged strings of crystal cavities radiating downward in

conical groups. These seem to have been crystals which grew in the sedi-

ments, while the latter were still soft. Their growth in wet muds per-

fectly agrees with the other known features of the rock, and they seem to

have a definite place in the sedimentary cycle of deposition. Their

unique arrangement is as yet unexplained.

The Lockatong formation, while composed in the central part of mas-

sive argillites, is much more shaly on the margins, and passes by gradual

stages into the other Triassic formations above and below it, through a

series of dove-tailing strata. Hence its boundaries are very uncertain,

and large portions of its upper and lower parts may as well be said to

belong to the series above or below as to the Lockatong. Therefore it is

our conclusion, which is similar to that stated by Dr. H. B. Ktimmel,”®

that the Lockatong series, as a definite geological time unit, is probably

valueless, since part or all of the formations seem to be contemporaneous

with portions of the Stockton and Brunswick series elsewhere. |

There are three principal joint directions, the most important of which,

occupied by the major joint series (tension joints), is remarkably con-

stant in direction throughout the area. It affects all the Lockatong rocks,

and is also found on the borders of the intrusive diabasé mass of Rocky

Hill, an extension of the Palisade sill, but not far within the latter.

Titanium minerals—brookite and ilmenite—are found in these joints,

apparently far removed from diabase, together with analcite and barite,

whose derivation from the intrusive rocks is indicated by the occurrence

of the same minerals in similar joints in the immediate vicinity of the

trap rocks at Byram, Hunterdon Co., N. J., and elsewhere. The occur-

rence of such minerals in the joint cavities of sedimentary rocks, two

miles from the nearest visible igneous rock, is worthy of special note.

The hypothesis is advanced that these major joints were formed very soon

after the intrusion of the igneous mass, at the beginning of a tectonic

disturbance which widely affected the Triassic beds; and that later move-

ment took place along a very few major fault lines.

The Lockatong argillite is very dense and close grained, as shown by

experiment. This, together with its remarkable siliceous cement and the

*° KUMMEL, H. B. Rept. State Geologist of N. J. for 1897, p. 41.

HAWKINS, LOCKATONG FORMATION OF THE TRIASSIC 175

absence from it of minerals which might decompose, renders it a very

strong rock. It has been and is being used extensively as building ma-

terial in Princeton, and it should be better known elsewhere.

BIBLIOGRAPHY

Berkey, Cuas. P. Geology of the New York City (Catskill) Aqueduct.

N. Y. St. Mus. Bull. 146. Albany, 1909.

Brown, A. P. New Cyeads and Conifers from the Trias of Pennsylvania.

Proc. Acad. Nat. Sci. Phila., pp. 17-21. 1911.

Butter, Francis H. The Brecciation of Mineral Veins.

Mineral. Mag., Vol. XVI, No. 74. October, 1911.

CLARKE, F. W. The Data of Geochemistry.

U. S. Geol. Surv., Bull. 491. 1911.

Dag, T. NELSon. Structural Details of the Green Mountain Region.

U. S. Geol. Surv., 16th Ann. Rept., p. 549. 1894-’95.

Davis, W. M. The Structure of the Triassic Formation of the Conn. Valley.

U. S. Geol. Surv., 7th Ann. Rept., pp. 455-490. 1888.

The Triassic Formation of Connecticut.

U. S. Geol. Surv., 18th Ann. Rept., pp. 1-192, 1896-97 (1898).

EASTMAN, CHAS. R. Triassic Fishes of Connecticut.

Conn. Geol. Surv., Bull. 18, pp. 1-75. 1911.

GaGE, R. B. Determination of Ferrous Iron in Magnetite.

Jour. Am. Chem. Soc., 31, pp. 381-885. 1909.

HAWKINS, ALFRED C. Some Interesting Mineral Occurrences at Princeton, N. J.

Amer. Jour. Sci., 4th Ser., Vol. XX XV, pp. 446-450. 1913.

JONES, T. R. A Monograph of the Fossil Estherie.

Paleont. Soc. Lon., 1862.

LEITH, CHAS. K. Rock Cleavage.

U. S. Geol. Surv., Bull. 239. 1905.

LEWIS, J. VOLNEY. Building Stones of New Jersey.

Ann. Rept. State Geol. New Jersey, 1908, part ITI.

Lut, R. S. The Life of the Connecticut Trias.

Amer. Jour. Sci., 4th Ser., Vol. XX XIII, pp. 397-422. 1912.

LYMAN, B. S. The New Red of Bucks and Montgomery Counties.

Summary Final Report, Second Pennsylvania Geological Survey, Vol. 3,

part 2, p. 2610, 1895.

Nason, F. L. Ann. Rept. State Geol. New Jersey, 1888, pp. 28-29

NEw JERSEY. Annual Reports of State Geologist, 1880, 1881, 1888, 1896, 1897,

1906, 1907, 1908.

RUSSELL, I. C. Correlation Papers; The Newark System.

U. S. Geol. Surv., Bull. 85, pp. 126-131. 1892.

SHALER, N. S., and WoopwortH, J. B. Geology of the Richmond Basin, Vir-

ginia.

U. S. Geol. Surv., 19th Ann. Rept., pp. 385-519. 1897-98, 1899.

Spring. W. Ueber die eisenhaltigen Farbstoffe sedimentiirer Erdboden und

iiber den wahrscheinlichen Ursprung der rothen Felsen.

Neues Jahrb. fiir Min., Geol. und Pal.. Jahrg., 1899: 1 Bd., erstes Heft,

p. 47.

176 ANNALS NEW YORK ACADEMY OF SCIENCES

UNITED STATES GEOLOGICAL SURVEY.

Trenton Folio, No. 167 (N. J.-Pa.), p. 7.

Philadelphia Folio, No. 162 (Pa.-N. J.-Del.), p. 8.

VAN Hise, CHAs. R. A Treatise on Metamorphism.

U. S. Geol. Surv., Monog. XLVII, 1904.

WHEATLEY, CHAS. M. Remarks on the Mesozoic Red Sandstones of the Atlan-

tic Slope, and Notice of the Discovery of a Bone Bed Therein, at

Pheenixville, Pa.

Amer. Jour. Sci. and Arts, Vol. XXXII, pp. 41-48. 1861.

WHe_erry, Epear T. Contributions to the Mineralogy of the Newark Group of

Pennsylvania.

Trans. Wagner Free Inst. Sci., Vol. VII.. February, 1910.

North Border Relations of the Triassic in Pennsylvania.

Proce. Acad. Nat. Sci., Phila., 1918, pp. 114-125.

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ANNALS OF THE NEW YORK ACADEMY OF SCIENCES

> Vol. XXIII, pp. 177-192

Editor, EpmMunD OtT1s HovEY

REVISION OF THE GENUS ZAPHRENTIS

Marsorie O’ConneELL, A. M.

| NEW YORK

- PUBLISHED BY THE ACADEMY

25 FEBRuARY, 1914

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(Lycrum or Naturat History, 1817-1876)

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[ANNALS N. Y. Acap. Scr., Vol. XXIII, pp. 177-192, 25 February, 1914.]

REVISION OF THE GENUS ZAPHRENTIS

By Margorie O’ConnELL, A. M.

(Presented by title before the Academy, 1 December, 1913)

The status of the genus Zaphrentis and of two or three allied genera

has been the subject of considerable discussion, opinions as to the generic

types and descriptions varying widely, and being founded, as a rule, not

upon the original descriptions but upon their subsequent interpretations.

The study whose results are given in the present communication was

undertaken for the purpose of establishing the facts of the case. Original

descriptions and figures have in all cases been consulted, and the discus-

sions and synonymies of later writers have been studied and compared.

In the older descriptions, which are all in French, it has been necessary

for the sake of clearness to introduce. modern terminology, but the origi-

nal French is given throughout in foot-notes so that verification of the

translation and of the interpretation is possible.

The genus Zaphrentis was first described in 1820 by Rafinesque and

Clifford (1, 234) ,* the following characters being noted :

Exterior striated, calyx with straight septa, axis almost central, mamellose,

striated excentrically by flexuose lines diverging from an excentric point near

a deep, lateral, oblong gap, dorsal, or situated near the convex curvature. The

animal must have had a particular organ corresponding to that gap and to the

axis of radiation.”

Five species are described, namely, Z. campanula, Z. phrygia, Z. cart

nata, Z. concava and Z. angulata, all from the Falls of the Ohio, but the

descriptions are very indefinite and lacking in detail, and the only form

which can be recognized is Z. phrygia. This is characterized as

turbinate, wrinkled; calyx oblique, campanulate, center concave, septa lamel-

lar; base curved, obtuse, entire. A small species resembling a Phrygian bon-

net, reversed.®

1 The first number in the parenthesis refers to the same number in the bibliography at

the end of this article, the second to the page references.

2“Striée extérieurement, étoile 4 rayons droits, axe presque central, mamellonné,

radié excentriquement par des rayons flexeux divergeant d’un point excentrique prés d’un

trou oblong, profond, latéral, dorsal ou situé du coté de la courbure convexe. L’animal a

df avoir un organe particulier correspondant A ce trou et a l’axe radié.”

*“Turbinée, ridée; etoile oblique campanulée, centre concave, rayons lamellaires; base

ao obtuse, entiére.—Petite espéce resemblant 4 un bonnet phrygien renversé,” Ci,

35.)

(177)

a. nannian ;

Yi x YS) ‘ a NStit Ss *

178 ANNALS NEW YORK ACADEMY. OF SCIENCES

This is a rather meager description and yet it 1s all there really is for

the type of the genus Zaphrentis. It must be remembered that methods

of study were not as exact then as now, and that generally not all the

important characters in a specimen were noted and recorded. ‘The main

points recognized by Rafinesque and Clifford are the turbinate, curved

corallum ; straight septa; external strizw, and the fossula, situated either

dorsally or on the convex curvature.

In the same year there appeared in Paris a paper on corals by Lesueur

(2) in which occurs the following description of a species called Caryo-

phyllia cornicula: Pe

It occurs singly, of a simple form, without the appearance of a base for

attachment, horn-shaped, longitudinally striate, with gentle transverse undu-

lations.

Upper extremity broad, with thin edge; calyx more or less concave, septa

serrate; two or three inches in length.*

Both of these papers seem to have been forgotten for about thirty

years, for later authors did not refer to them during that time. Har-

douin Michelin in 1840, apparently never having heard of the genus

Zaphrentis, described a new genus at the Congress of Turin and dedi-

cated it to M. Charles Bonaparte, Prince of Canino, calling it Canina.

At this time, no species was mentioned, and it was not until the publica-

tion of the “Iconographie Zoophytologique” that we find all the species

and figures given. This book is made up of various parts brought out

from time to time during the years from 1840 to 1847. Corals from the

Carboniferous to the present are described, the whole book being arranged

on a geographical rather than a zodlogical plan; that is, for each locality

considered, all of the corals are described, and thus we find the four

species of Canina treated at different times and in different parts of the

book. Caninia is first mentioned in the Iconographie in the description

of the Sable fauna on page 81 without generic diagnosis, C. gigantea

being there described. It was not until several years later in the discus-

sion of the Tournay fauna that C. cornucopie was first figured. (5, pl. 59,

fig. 5.) Thus one of the mistakes which has long been made as to the

type of the genus is accounted for. For the reason that C. gigantea® is

the first species of Canina described in this book, it has by some authors

been considered the genotype of Caninia, the genus being considered

4“Se présente isolée, en tige simple, sans apparance de base pour se fixer, d’une forme

corniculée, striée longitudinalement, avec de légéres ondulations transverses. 5

“Wxtrémité supérieure large, 4 bord mince; étoile plus ou moins concave, rayons

serrés ; deux 4 trois pouces de longueur.” (2, 297, 298.)

~8 Oaninia gigantea of Michelin must not be confounded with Caryophyllia gigantea

Lesueur, which is entirely distinct and will be considered below.

“4

O’CONNELL, REVISION OF THE GENUS ZAPHRENTIS 179

synonymous with Zaphrentis. It was described first, however, merely

because Michelin took up the fossils of Sable before those of Tournay,

where the other species occur. These three others are C. cornu-bovis,

QC. patula and C. cornucopie, given in the order in which they appear in

the “Iconographie Zoophytologique.” Carruthers has recently stated

(22, 159, 166, 168) that C. cornu-bovis represents a developmental stage

in the ontogeny of C. cornucopiv, being the adult of the latter, and it

should, therefore, be included under C. cornucom@ in all synonymies.

Carruthers not only studied the original descriptions and figures, but also

had the opportunity to examine the type material and many other speci-

mens from Tournay. Nevertheless, if Michelin’s figure of the type of

C. cornucopie (Pl. 59, fig. 5) is of natural size, we cannot accept this

determination, though we can easily understand that the very young of

C. cornu-bovis has the character of C. cornucopia. C. cornu-bovis has,

however, the adult characters of the genusYSiphonophyllia as discussed

below. C. patula, on the other hand, agrees with C. cornucopia. If C.

cornu-bovis were the type of CaniniasSiphonophyllia would have no

generic standing. Lambe and other American authors have selected C.

patula as the type of Caninia, but there seems to be no good ground for

this selection. The question, however, is easily settled, for Michelin ex-

pressly stated (4) that cornucopie was the type of Caninia® and he gave

the following description:

Stony polyp, free or fixed, sub-turbinate, simple, cylindrical, formed of super-

posed cellules (cups) each cell furnished marginally with lamellze sometimes

very short and twisted, sometimes reaching the center, but remarkable in that

they can be separated into little conoid funnels representing beyond doubt the

succession of the principal vital phases of the polyp, and set one into the other

around and forward from the central axis; exterior striated.’

This description is composite and fits C. cornu-bovis better than it

does the other two species; but since the type of the genus was definitely

named, the generic characters must be determined by it. These are given

in the summary at the end of the paper.

The selecting of patula as the type may possibly be explained in the

following way: C. gigantea, as will be shown below, does not belong to the

' 6 “CO. cornu-copiw, Mich. Espéce type de genre dédié au prince Ch. Bonaparte.”

7™“Ses caractéres sont: polypier pierreux, libre ou fixe, subturbiné, simple, cylindrique,

formé de cellules superposées chaque cellule garnie marginalement de lamelles, quelque-

fois trés courtes et sinueuses, quelquefois § atteignant le centre, mais remarquable en ce

qu’il est décompasable en petits conoids, representant sans doute la succession des prin-

cipales phases vitales du polype, et s’emboitant les uns dans les autres en dehors et en

avant de l’axe central; l’exterieur est strié.’”’ (22, 166.)

8 Introduced by Carruthers for the sake of clearness.

180 ANNALS NEW YORK ACADEMY OF SCIENCES

same group as the other species of Canina, but possesses very distinctive

characters. The discarding of C. cornu-bovis as identical with C. cornu-

copie would leave C. patula as the first described species in the Iconog-

raphie and thus it would become the type. Recognizing the true rela-

tions that have just been pointed out, it is evident that C. patula must

give way to C. cornucopia as the genotype of Caninia.

In 1844 Scouler (7, 187) introduced the name Siphonophyllia with

Caninia gigantea Michelin as his genotype, giving as his diagnostic char-

acter the peculiar kind of fossula formed by the down-bending and invagi-

nation of successive tabula. This name, however, has never been used.

Edwards and Haime in 1851 gave a complete discussion of the earlier

forms which had been described, and they made Caryophyllia cornicula

Lesueur the type of Zaphrentis, for they found that of the five species of

Zaphrentis given by Rafinesque and Clifford, Z. phrygia was the only

one recognizable and this they identified as being the same as Lesueur’s

Caryophyllia cornicula. Since both Rafinesque and Clifford’s, and Le-

sueur’s papers appeared in scientific journals in the same year, there is

no way of telling from a mere inspection of these volumes which one was

published first, but apparently Edwards and Haime consider that Lesueur

has precedence. The synonymy for Zaphrentis cornicula thus includes

Caryophyllia cornicula Lesueur, Zaphrentis phrygia Rafinesque and Clif-

ford, Caryophyliia cornicula Milne Edwards (8, 351), Caninia punctata

D’Orbigny. Z. cornicula is described as

a slightly elongated cone, rather strongly curved at the base, especially in

young forms, and surrounded by a thin epitheca showing swellings and circular

eonstrictions. Uniform and rather fine ribs can be detected in some indi-

viduals, cutting obliquely the dorsal line, which follows the convex curvature.

Calyx circular, large and deep; fossula oblong, deep, situated near the convex

curvature and prolonged above to form a marked groove. Septa rather regu-

larly radiating. Ordinarily 72 to 92 septa may be counted, alternating and

somewhat unequal, strongly serrate, thin, very narrow above, not exert. Their

margin divided into projecting points, serrate, scarcely horizontal and largest

in the middle of the free portion. The principal septa reach the center of the

calyx, where they are covered and slightly raised. In certain individuals, in

which the upper tabula is removed, and in which possibly some septa are partly

destroyed, a small smooth portion at the center of the tabulz may be seen.

The large examples are 8 centimeters high, the calyx is 5 centimeters in diam-

eter and 38 centimeters deep. Young forms are often found which are only 3

centimeters deep and 2 centimeters in diameter.’

®“Polypier en cOne médiocrement allongé, 4 base assez fortement arquée, surtout dans

le jeune age, et entouré d’une épithéque mince et présentant quelques bourrelets et quel-

ques étranglements circulaires. On distingue sur quelques individus des cotés égales et

assez fines, qui viennent couper obliquement la ligne dorsal qui suit la grande courbure.

Calice circulaire, grande et profonde, fossette septale oblongue, profonde, située du coté

O’CONNELL, REVISION OF THE GENUS ZAPHRENTIS 181

Considering Edwards and Haime’s synonymy species by species, we

find that the description of Lesueur’s Caryophyllia cornicula agrees with

that of Zaphrentis cornicula E. and H. so far as it goes, but it contains

no reference to a fossula which in Z. cornicula is “deep, situated near the

convex curvature and prolonged upward to form a very marked groove.”

(9, 327.) In giving the localities where C. cornicula is found, Lesueur

says that

many rolled forms [i. e., water-worn forms] are found along the borders of

Lake Erie, near Eighteen-Mile Creek. The most perfect individuals are en-

closed in the most compact banks which also contain the terebratulas [brachi-

opods].

He adds:

With this species I have found a great quantity of little spherical globules,

with spiral strie, as in the Gyrogonites of Europe” [a genus of fossil Cha-

races]. That, however, could be another species.”

He also had specimens from Kentucky which were undoubtedly what

are now commonly known as Zaphrentis (Heliophyllum) corniculum and

were the same as the Zaphrentis of Rafinesque and Clifford, also from

Kentucky. As for the Eighteen-Mile Creek forms, the only rugose corals

which answer to his description are Streptelasma (Stereolasma) rectum,

so far as the form is concerned, and Heliophyllum hall, the only cari-

nated species which occurs in great abundance there.

It is quite probable that the Eighteen-Mile Creek forms referred to

this species are all Stereolasma rectum, which in form closely resembles

Z. corniculum. The Highteen-Mile Creek specimens almost never show

de la grande courbure et se prolongeant en haut sous forme d’une rainure bien marquée.

Appareil cloisonnaire assez réguliérement radié. On compte ordinairement de 72 a 92

cloisons alternativement un peu inégales, qui sont trés-serrées, minces, fort étroites en

haut, non débordantes. Leur bord est divisé en points saillants, serrées, 4 peu prés hori-

zontales et plus grandes sur le milieu de la partie libre. Les principales cloisons arri-

vent jusqu-au centre de la fossette calicinale, ou elles sont légérement courbées et un peu

relevées. Dans certains individus dont le plancher supérieur est enlevé, et dont peut-

étre les cloisons ont été partiellement détruites, on voit une petite partie lisse sur le

milieu des planchers. Les grands exemplaires ont 8 centimetres de hauteur, le calice est

large de 5 et profond de 3. On trouve fréquemment des jeunes qui no sont hauts que

de 3 centimétres et larges de 2.”’ (9, 327, 328.)

10 This is, however, a mistake so far as the Lake Erie shore near Highteen-Mile Creek

is concerned. No such bodies occur there, but they abound with Z. cornicula in the

Columbus limestone of Ohio. It is quite evident that specimens from both localities

were commingled.

u “On en. rencontre beaucoup de roulés sur le bord du lac Erié, prés de dix-huit mille

erick. Les individus plus parfaits sont renfermés, dans les banes les plus compacts, qui

font partie de ceux 4 térébratules.

“Avec cette espéce j'ai rencontré une assez grande quantité de petits globules sphé-

riques, avec des stries en spirale, comme dans la gyrogonite d’Europe. Celle-ci en seroit

une autre espéce.”’ (2, 298.)

182 ANNALS NEW YORK ACADEMY OF SCIENCES

the septa, and it is quite probable that identification was made by form

and size only, the septal characters being taken from Ohio or Kentucky

specimens of Z. corncula.

In the Columbus limestone of Ohio the latter are often found associ-

ated with the spherical, spirally striated globules Calcisphera robusta. It

is thus evident that Lesueur included under his Caryophyllia cornicula

several species. This was not an uncommon thing for authors to do at

that time, when they tried to fit in many quite diverse forms under the

already established genera.

Zaphrentis phrygia has already been discussed, but it may be well to

add that a number of specimens in the Columbia University collection

may readily be identified with 7. phrygia as originally described, and

they agree perfectly with the description of that species in form, size,

fossula and strie and particularly in the distinctive obtuse angle of the

base. The only difference between these specimens and the description is

the presence of carinz, which makes it seem as though, inasmuch as these

specimens came from the type locality, Rafinesque and Clifford over-

looked, or failed to mention the carine, particularly since Edwards and

Haime, who probably had the type material before them, make the carinze

one of the characteristics of this species of Zaphrentis.

In the second edition of Lamarck, edited by Deshayes and Milne Kd-

wards, the species Caryophyllia cornicula of the latter author is described

simple, corniculate, striate, with transverse undulations dilating toward the

apex; calyx concave; septa serrate.”

D’Orbigny merely mentions the species Caninia punctata, but does not

describe it. (8, 105.)

All of those forms, then, are included by Edwards and Haime under

Zaphrentis cornicula. It is interesting to note that although cornicula is

the type for Zaphrentis, it is now usually accepted as one of the most

common forms of Helophyllum and was described as H. corniculum by

Hall in 1882 as follows:

“Corallum simple, turbinate, regularly curved, acute at the base, rapidly

expanding; exterior with shallow constrictions; the surface usually compara-

tively smooth; on well preserved specimens the costz are prominent; height

usually from thirty to thirty-five millimeters, diameter from twenty to twenty-

five millimeters, though examples have been found seventy millimeters in

height and forty-five millimeters in diameter; one calyx of twenty-five milli-

meters diameter has a depth of fifteen millimeters; the sides descend regularly

122°C, fossilis simplex, corniculata, striata, transversim undulata, ad apicem dilata:

stella concava; lamellis dentatis.”” (3, 351.)

O'CONNELL, REVISION OF THE GENUS ZAPHRENTIS 183,

and abruptly, leaving at the bottom a flattened area about fifteen millimeters

in diameter; fossette commencing just posterior to the center and continuing

to the posterior margin, much more prominent on the bottom of the calyx; the

larger lamellz continue to the center, slightly twisted; from six to eighteen

denticulations in the space of five millimeters; near the margins of the cup

they are thin and somewhat obscure, on the sides they are very prominent and

spiniform. . . . Although usually placed in the genus Zaphrentis, this form

presents the characteristics of the genus Heliophyllum.” (17, 311, 12.)

To the genera Zaphrentis and Caninia was added a third, Hetero-

phrentis, by Billings in 1872, to include the species spatiosa, excellens,

prolifica and others which were formerly placed under the genus Zaph-

rentis. ‘The type is spatiosa, described as follows:

“Corallum simple, turbinate. Calice large, with a well-defined septal fos-

sette, the bottom either smooth or with a pseudocolumella. Septa below the

calice sharp-edged, often with their inner edges twisted together; above the

floor of the calice they are usually rounded, especially on approaching the

margin. There is apparently only a single transverse diaphragm, and this

forms the floor of the cup.” (12, 236.)

Lambe comments on this genus in his description of Streptelasma pro-

lificum, saying,

“The writer is inclined to believe that the species Heterophrentis spatiosa,

Billings, is founded on short and unusually widely expanding specimens of

S. prolificum. The two type specimens are from Rama’s Farm, Port Colborne,

Ontario. Mr. Billings was doubtful as to the validity of the species and con-

cluded the original description with the remark that it is “closely related to

Z. prolifica, and may perhaps be united with it when its characters become

more fully known.” (21, 117.)

Furthermore, Billings states that

“It is difficult, perhaps impossible, to decide whether this group of forms is

specifically distinct from H. excellens. The greatest difference is seen in the

surface characters. In H. excellens the folds of growth are in general numer-

ous and angular, although some are rounded. In JH. prolifica they are in gen-

eral few and nearly always rounded. In H. ezxcellens I have only been able

to make out the septal strie distinctly in one specimen. At 1 inch from the

base there are 5 and at 2% inches 4, in the width of 3 lines. In Z. prolifica

there are 8 to 10 at 1 inch, and 6 to 8 at 21% inches.” (T2021)

Since Billings was not certain of the specific distinction of H. spatiosa

and H. excellens and considered them as probably only forms of H. pro-

lifica, the description of which follows, this latter form then becomes the

type of Heterophrentis.

184 ANNALS NEW YORK ACADEMY OF SCIENCES

HETEROPHRENTIS PROLIFICA Bill.

Billings’ emended description, 1874:

“Corallum simple, turbinate, curved, expanding to a width of from 18 to 24

lines in a length of from 2 to 4 inches. Surface with a few undulations of

growth. Septal strie 8 to 10 near the base and 6 to 8 in the upper part in

a width of 3 lines. Septa from about 100 to 120 at the margin (where they

are all rounded), most common number from 100 to 110. In general they alter-

nate in size at the margin; the small ones becoming obsolete on approaching

the bottom of the calice; the large ones more elevated and sharp-edged. The

septal fossette is large and deep, of a pyriform shape, gradually enlarging

from the outer wall inwards for one-third, or a little more of the diameter of

the coral, at the bottom of the calice.* Its inner extremity is usually broadly

rounded or, sometimes, straitish, in the middle. It cuts off the inner edges of

from 8 to 12 of the principal septa which may be seen descending into it to

various lengths. The surface layer of the bottom of the cup extends the whole

width, bending downwards a little near the margin, as in Zaphrentis, and

uniting with the inner wall of the cup all around. It thus seems to represent

one of the tabule of a Zaphrentis. The following are the principal variations

observed in this part of the fossil.

“1. Specimens with a perfectly smooth space in the bottom of the cup; no

columella.

“2. A smooth space with a small conical tubercle near the center.

“3. Smooth with a small ridge, two lines in length and half a line in height

and width.

“4. Smooth with a compressed columella 3 lines in length, 2 lines in height,

most elevated next to the fossette, gradually declining in height towards the

opposite side.

“5. Smooth spaces very small, columella a low ridge, with a few tubercles on

its crest.

“6. Columella well developed, but with tubercles on it and around it.

“7, Septa reaching the columella and more or less corrugated and either with

or without a columella.

“Tn all cases where the columella is elongated, its length extends in a direc-

tion from the fossette to the opposite side. In those which have the septa

extending to the centre the columella is often represented by a low rounded

elevation.” (12, 206, 237.)

In 1900 George B. Simpson published a preliminary description of new

genera of Paleozoic rugose corals, in which he includes several species

formerly referred to Zaphrentis. He erected the genus Hapsiphyllum for

such zaphrentoid corals, which like Z. calcarifornis Hall of the St. Louis

beds, the genotype, have a horse-shoe shaped inner wall, formed origi-

nally by the bending over and uniting of the ends of the septa. The

cardinal septum and fossula lie within the area thus enclosed. Another

genus made by him is T'riplophyllum vith Zaphrentis terebrata Hall as

O’CONNELL, REVISION OF THE GENUS ZAPHRENTIS 185

the genotype, and Z. centralis, E. and H. and Z. dalw, E. and H. as other

examples. These species differ from normal Zaphrentis and Hetero-

phrentis in having the septal arrangement arrested in the primitive quad-

ripartite manner characteristic of the young of rugose corals generally.

Thus two lateral or alar pseudo-fossule are retained. There are no den-

ticulations or carine on the thickened septa. The genera are Devonian

and Mississippian in age.

A third generic term proposed by Simpson is Scenophyllum, with

Zaphrentis conigera Rominger as the genotype. This, however, has no

close relationship to other zaphrentoids. Finally, he proposed the genus

Homalophyllum for such species as Zaphrentis ungula Rominger and

Zaphrentis herzeri Hall, which are flattened on the side of greatest curva-

ture. It is not at present certain that the two species named are con-

generic, in spite of this flattening on one side.

There has been little discussion of these genera during recent years,

until in 1908 Carruthers published a paper entitled “A Revision of Some

_ Carboniferous Corals,” in which he especially considers the standing of

‘the genus’Caninia. He went to the sources in the literature, and after

carefully examining not only many specimens of Caninia cornucopie and

allied forms, but also several hundred from the type locality, Tournay,

and numerous examples from the Bristol area, he gives a re-definition of

the genus as follows:

“Corallum simple, turbinate and conical, often slender and cylindrical for a

great part of its length.

“Major septa well developed and meeting in the centre in the lower, conical

part of the coral, but in the cylindrical portions usually becoming amplexoid

in character.

“Minor septa of various lengths in different species.

“Cardinal fossula variable in extent, characteristically limited by tabulz

only, at the inner end, and with flanking septa loose or disconnected.

“Tabule well developed, but variable in regularity; they may be highly

arched and vesicular. A marginal ring of more or less vertical dissepiments,

usually thin and delicate, intervenes in the mature stages of growth between

the tabule and the wall.” (22, 158.)

In this definition he includes species of the type of C. cornu-bovis,

which he considered identical with C. cornucopia.

The most recent paper on Caninia is that of Achille Salée, “Contribu-

tion a l’Etude des Polypiers du Calcaire Carbonifére de la Belgique,”

published in 1910. Much of his discussion is based on Carruthers’ work

and he gives no synonymy, merely referring to that given by Carruthers.

His paper, however, is comprehensive and brings out many points not

previously emphasized. He states the differences between Caninia, in

186 ANNALS NEW YORK ACADEMY OF SCIENCES

which he includes Siphonophyllia, and forms which have been confused

with it as follows:

It differs from Zaphrentis [including Siphonophrentis as defined below, and

Heterophrentis| by the following characters:

1. The fossula of Zaphrentis is limited at the center of the calyx by a regular

border, formed by the union toward the interior of the larger septa nearest the

eardinal septum, and the tabular depression of the fossula is always extremely

deep.

2. Even in the adult, Zaphrentis does not have the external vesicular zone,

even in a reduced condition.

3. In Zaphrentis. there is a stereoplasmic band adhering to the epitheca,

while in Caninia, that stereoplasmic band detaches itself from the epitheca to

form an internal wall; that wall is separated from the epitheca by the ex-

ternal vesicular zone.”

The wall is not a true one as in the case of Eridophyllum and Craspe-

dophyllum, but only a pseudotheca. The author continues:

Caninia differs from Cyathophyllum in the following characters :

1. The fossula in Cyathophyllum is simply indicated, if not absent; radial

symmetry is altogether dominant.

2. The vesicular dissepiments affect in Cyathophyllum a regularity which is

never attained in Caninia. i al

3. In Cyathophyllum, there is not a very decided separation between the

external vesicular zone and the middle zone. The striking character which

gives to the middle zone the stereoplasmic thickening of the septa is lacking

in Caninia.

4. In Cyathophyllum the tabulze are very near together and are united by

many transverse lamellze, so that they become an irregular mass of rather

large vesicles.

13 “T) différe de Zaphrentis par les caractéres suivants (pl. ix, fig. 1, 2):

“1. La fossette des Zaphrentis est limitée au centre du polypier par une bordure

réguliére, formée par la réunion vers l'intérieur des septa majeurs les plus voisins du

septum cardinal, et la dépression tabulaire de la fossette est toujours extrémement pro-

fonde ;

“2. méme a l’age adulte, les Zaphrentis n'ont pas de zone vésiculaire externe, méme

reduit ;

“3. chez les Zaphrentis, il y a une bande stéréoplasmique collée A l’épithéque tandis

que chez Caninia, cette bande stéréoplasmique se détache de l’épithéque pour former une

muraille interne; cette muraille interne est separée de l’épithéque par la zone vésiculaire

externe.”’ (24, 13.)

4 “OCaninia différe de Cyathophyllum par les caractéres suivants (pl. ix, fig. 8 et 4):

“1°. la fossette chez Cyathophyllum est simplement indiquée, si pas absente; la

symmétrie radiaire est tout a fait. dominant ;

“2°. les vésicules dissepimentales affectent chez Cyathophyllum une régularité qui

n’est jamais atteinte dans Caninia;

“3°. chez Cyathophyllum, il n’y a pas de séparation bien tranchée entre la zone

vésiculaire externe et la zone moyenne. La caractére frappant que donne a la zone

moyenne l’epaississment stéréoplasmique des septa chez Caninia fait ici défaut ;

“4°. chez Cyathophyllum les planchers sont trés rapprochés et réunis par le multi-

ples traverses, de sorte qu’ils deviennent un amas irrégulier de vésicules assez large.”’

24, 15, 16.)

O'CONNELL, REVISION OF THE GENUS ZAPHRENTIS 187

The species Caninia gigantea Michelin, which Salée includes in his re-

vision of the genus“as a true Caninia, does not seem to fit in with the

typical Caninia (C. cornucopie), inasmuch as its fossula is formed not by

the meeting of the septa and the abortion of the cardinal septum, but

rather by the down-bending of the successive tabule to form a series of

invaginated funnels, upon which characteristic Scouler based his genus

Siphonophyllia, making C. gigantea Michelin the genotype. This down-

bending ot the tabule forms not a true fossula, which is due to the abor-

- tion of the cardinal septum (23, 48), but a peculiar type which may be

designated a “siphonofossula,” and which may or may not be accompanied

by an abortion of the cardinal septum. Moreover, Caninia gigantea can-

not be included under Zaphrentis, as typified by Z. cornicula, although

Edwards and Haime considered it as such, changing the name to Z.

cylindrica in order to distinguish it from Lesueur’s Caryophyllia gigantea,

which is commonly regarded as a typical Zaphrentis in the usual use of

the term. Thomson and Nicholson tentatively referred this species to

Cyathophyllum, because it has the tabule restricted to the central area,

and has a well-marked circumferential zone of lenticular cells,but still it

‘differs from Cyathophyllum in the possession of this pronounced and

unique siphonofossula. The name Cyathophyllum giganteum was given

only temporarily until further restrictions should be made. With the

more precise definition of the genera, Canina gigantea Michelin, cannot

be placed under either Caninia or Zaphrentis, but should be left as the

\ type of the genus Siphonophyllia which must be reinstated. Lesueur’s

species of Caryophyllia gigantea was found in Kentucky and described

in 1820. This is the form commonly known as Zaphrentis gigantea

(Lesueur). That it cannot be placed in the same genus with Z. corni-

cula, the genotype of Zaphrentis, is evident, for it differs from the typical

Zaphrentis in having the tabule well developed, numerous, extending

entirely across the visceral chamber and bending down marginally. There

is no external vesicular zone, in which respect it agrees with true Za-

phrentis. On the other hand, the fossula is formed in the same manner as

in Siphonophylhia gigantea (Mich.) and is really a siphonofossula, the

cardinal septum being visible throughout the entire individual. Since

both Caninia gigantea and “Caryophyllia’”’ gigantea have this siphon-

like pseudofossula, and since both species are distinct and yet are generi-

cally misplaced, Scouler’s genus Siphonophyllia, which he originally based

on the former species as the genotype should be revived with that species

as type, while the name Siphonophrentis may be adopted for the other

‘species, Caryophyllia gigantea Lesueur being the genotype.

Les ANNALS NEW YORK ACADEMY OF SCIENCES

In looking over this rather confused array of facts and opinions, it 1s

evident that much of the inexactness in the use of generic terms is due

to carelessness on the part of authors in consulting original descriptions

and often to their not consulting them at all. This is particularly the

case with forms referred to Zaphrentis. ‘There is a prevailing idea about.

the character of this coral, but it seems to have arisen from the opinions

expressed by various authors as to what they considered the characters

should be, and not from a study of the original description and figures.

For instance, Thomson and Nicholson have restricted the genus Za-

phrentis, stating that it can be recognized

“by the complete, or comparatively complete, development of the septal system,

the great development of the tabula, the existence of a fossula, which is formed.

by the coalescence centrally of a certain number of the septa, and the fact

that the dissepiments are in no case sufficiently developed to form an exterior

zone of vesicular tissue.” (14, 428.)

Carruthers in his discussion of Zaphrentis bases his generic description

upon that given by Thomson and Nicholson, adding that the description

“does not pretend to be founded on the specimens from which the original

diagnosis was prepared,” but “it undoubtedly represents the genus as

understood at the present time.” He retains the “conventional defini-

tion” and Salée, two years later, follows Carruthers. Thus authors have

been satisfied to take somebody else’s interpretations, instead of going to

the sources.

The last genus to be separated from Zaphrentis is Heliophrentis, de-

scribed in 1910 by A. W. Grabau (25, 98), with H. alternata Grabau

from the Upper Monroe as the genotype. This is a carinate species

closely related to and congeneric with Zaphrentis racinensis Whitfield of

the Niagara. These species may be congeneric with Zaphrentts cor-

nicula, and hence belong to the true Zaphrentis, but at present nothing

but the form and calicinal structure is known.

I. Briefly reviewed, the facts are these: the genus Zaphrentis, first:

described by Rafinesque and Clifford, was found by Edwards and Haime,

who probably had the type material, to contain only one recognizable:

species and that was Z. phrygia. This they considered the same as:

— Caryophyllia cornicula Lesueur, described from the same locality and

horizon, and called by them Zaphrentis cornicula. Since they gave the

first full and detailed description as well as figures, this species then be-

comes the virtual type of Zaphrentis. The distinguishing characteristics.

of the genus are as follows:

O’CONNELL, REVISION OF THE GENUS ZAPHRENTIS 189

Simple, elongated corallum, surrounded completely by an epitheca ; deep

alyx; a single, well-developed fossula, marking the abortion of the eardinal

septum; no columella ; numerous, well-developed, serrate septa with caring in

typical species; tabule imperfect or absent; the septa prolonged generally to

the center of the visceral chamber.

The forms such as gigantea, prolifica, and many others which are com-

monly considered as Zaphrentis, actually do not come under that genus

at all and consequently other generic terms must be sought. About con-

temporaneously with Zaphrentis appeared Lesueur’s Caryophyllia cornic-

ula, characterized by its simple, horn-shaped form, deep calyx, serrate

septa, and surface strie. This is the form which Edwards and Haime

identified with Zaphrentis phrygia and made the type of that genus.

Later Hall placed cornicula under Heliophyllum, mainly on account of

its well-developed carine. Since the carine are such an important fea-

ture in the type species, they cannot be omitted from later generic de-

scriptions, though more primitive species may be without them. Many of

the figures of Edwards and Haime’s species show the carine clearly as in

their Plate VI, figs. 1, 1a, 1c, 1d.

- II. The next generic name appearing in the historical development is

Caninia Michelin. ©. cornucopie has been definitely figured and de-

scribed as the type. It includes those curved forms with deep normal

fossula, numerous septa and tabule, external strie and no carine, which

are at present included under Zaphrentis.

~ III. In 1872 Billings restricted certain species of Zaphrentis to

Heterophrentis, with H. prolifica as the type and having at most a single

tabula at the base of the calyx, a marked fossula, frequently a columella

or a low rounded elevation; septa generally alternating in size, the

smaller ones becoming obsolete as they approach the center, the larger

ones becoming elevated, sharp-edged and sometimes twisted. This may

be extended so as to include species with few tabule such as Zaphrentis

simplex Hall.

~ IV. The name Siphonophyllia of Scouler is revived for forms like

Camma gigantea Michelin; 7. e., Zaphrentis cylindrica of Edwards and

Haime, which have numerous tabula, a peaiphonorossuls and a well-marked

external vesicular zone.

V. Simpson in 1900 proposed Hapsiphyllum for zaphrentoids, with a

horseshoe-shaped inner wall, making Zaphrentis calcareformis Hall the

genotype.

_ VI. Simpson also proposed T'riplophyllum for forms which, like Za-

phrentis terebrata Hall and others, retained the alar pseudo-fossule.

190 ANNALS NEW YORK ACADEMY OF SCIENCES

VII. For zaphrentoids flattened on the side of greatest curvature

Simpson proposed the generic name //omalophyllum, with Z. ungula

Rominger as the genotype.

VIII. Grabau in 1910 proposed Heliophrentis for Silurian zaphren-

toids characterized by carine. This may turn out to be synonymous with

Zaphrentis sens str.

IX. Finally, the term Siphonophrentis is here proposed for those forms

which like gigantea of Lesueur have numerous, well-developed tabulee

extending entirely across the visceral chamber, bending down marginally,

and, on either side of the cardinal septum, forming a series of invaginated

funnels giving a siphonofossula. There is no external vesicular zone.

The name Caryophyllia has a definite, restricted sense among modern

authors and cannot, therefore, be applied to the forms just characterized.

Siphonophrentis has for its genotype Caryophyllia gigantea Lesueur, the

form usually referred to as Zaphrentis gigantea from the Middle De-

vonian of eastern North America. In this as in the preceding genus, the-

tabule are the chief element, the septa being reduced.

SUMMARY OF THE REVISION OF THE GENUS ZAPHRENTIS

ZAPHRENTIS

(sens. lat.)

I. Zaphrentis Raf. and Clifford sens str. Silurian ? to Devonian.

Genotype: Caryophyllia cornicula Lesueur.

II. Caninia Michelin. Devonian to Mississippian.

Genotype: Caninia cornucopie Michelin. Other example, C.

patula Mich.

III. Heterophrentis Billings. Silurian ? to Devonian.

Genotype: Zaphrentis prolifica Billings. Other example, Z.

simplex Hall.

IV. Siphonophyllia Scouler. Mississippian to Carboniferous.

Genotype: Caninia gigantea Michelin. Other example, C.

cornu-bovis Mich.

V. Hapsiphyllum Simpson. Mississippian.

Genotype. Zaphrentis calcareformis Hall.

VI. Triplophyllum Simpson. Devonian to Mississippian.

Genotype: Zaphrentis terebrata Hall. Other examples, Z.

centralis, BH. & H., Z. dalu, E. & H.

VII. Homalophyllum Simpson. Devonian.

Genotype: Zaphrentis ungula Rominger. Other example, Z.

herzert Hall (?).

O’CONNELE, REVISION OF THE GENUS ZAPHRENTIS 191

VIII. Heliophrentis Grabau. Silurian to Devonian.

12.

13.

14,

15.

16.

17.

18.

Genotype: IZ. alternata Grabau. Other example, Zaphren-

tis racinensis Whitfield (may be true Zaphrentis).

IX. Siphonophrentis O’Connell. Devonian.

. 1820.

. 1836.

. 1840.

. 1844.

. 1850.

1883.

Genotype: Caryophyllia gigantea Lesueur (Zaphrentis gigan-

tea of most authors).

BIBLIOGRAPHY.

RAFINESQUE, C. S., and CLirrorD, J. D.: Prédrome d’une Monographie

des Turbinolies Fossiles du Kentucky (dans l’Amerique septen-

trionale). Annales Generales des Sciences Physiques, Bruxelles,

t. Vy pp. 234, 235.

LESUEUR, M.: “Description de pleusieurs Animaux appartenant aux

Polypiers Lamelliféres de M. 1. Ch. de Lamarck.” Mémoires du

Museum d’Histoire Naturelle, Paris, t. VI, pp. 296-298.

MILNE Epwarps in Annotations de la 2e edition de Lamarck Histoire

Naturelle des Animaux sans Vertébres, t. II, p. 351.

MICHELIN, HARDOUIN: In P. Gervais: article on ‘Astrza,’’ Diction-

naire des Sciences Naturelles, Supplement I, p. 485.

. 1840-1847. MiIcHELIN, HArpouIN: Iconographie Zoophytologique.

. 1842.

DrE Koninck, L.: Description des Animaux Fossiles du Terrain Car-

bonifére de Belgique, pp. 20, 21, 22, pl. C, fig. 4a, b, c, d, e, f, 9g.

M’Coy: Synopsis of the Carboniferous Fossils of Ireland, p. 187,

pl. xxvii, fig. 5. (Description of species by Scouler.)

D’OrBieny, ALCIDE: Proédrome de Paléontologie stratigraphique, t. 1,

p. 105.

EpWARDS, MILNE, and HAIME, J.: Monographie des Polypiers fossiles

des terrains paléozoiques, Archiv du Museum, Paris, Vol. V.

MILNE Epwarps, H.: Histoire Naturelle des Corallaires ou Polypes

Proprement dits, t. III, pp. 332-347.

De Konincrk, L.: Nouvelles Recherches sur Animaux Fossiles de

Terraine Carbonifére de la Belgique, p. 100, pl. x, figs. 5, 5b; pl.

Ky, fig; 2.

BILuines, E.: “On Some New or Little Known Fossils from the Si-

lurian and Devonian Rocks of Ontario.” Canadian Naturalist,

new series, Vol. VII, pp. 280-240.

NICHOLSON, H. A.: Paleontology of Ohio, Vol. VII.

THOMSON, JAMES, and NICHOLSON, H. ALLEYNE: Contributions to the

Chief Generic Types of the Paleozoic Corals. Annals and Maga-

zine of Natural History, 4th series, Vol. XVI, pp. 305-309, 424-429,

pl. xii; Vol. XVII, pp. 60-69, pls. vi, vii.

HALL, JAMES: Illustrations of Devonian Fossils.

ROMINGER, CARL: Paleontology of the Lower Peninsula of Michigan,

Vol .LIE.

HALL, JAMES: 12th Report of the State Geologist of Indiana.

1898-1899. GRaBau, AMADEUS W.: “Geology and Paleontology of Eighteen

Mile Creek.” Bulletin, Buffalo Society of Natural Sciences, Vol. VI.

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19.

20.

21.

22.

23.

24.

25.

1890.

1900.

1908.

1909.

1910.

ANNALS NEW YORK ACADEMY OF SCIENCES

WorTHEN, AMOS H.: Geological Survey of Illinois, Vol. VIII, p. 72,

pl. .ix, figs: I, Ie; pl. x, figs. 18, 134:

SIMPSON, GEORGE B.: Preliminary Descriptions of New Genera of

Paleozoic Rugose Corals. Bulletin of the New York State Mu-

seum, No. 39, Vol. 8, pp. 199-222.

LAMBE, LAWRENCE M.: Contributions to Canadian Paleontology, Vol.

PVE pts als pA aie

CARRUTHERS, R. G.: “A Revision of Some Carboniferous Corals.”

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pls. 4, 5, 6.

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Index Fossils, Vol. I.

SALEE, ACHILLE: Contribution a L’&tude des Polpiers du Calcaire

Carbonifére de la Belgique.

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and Biological Survey. Geological Series No. 1. The Monroe For-

mation, pp. 87-210, plates VIII to XXXII.

PALEONTOLOGICAL LABORATORY, COLUMBIA UNIVERSITY.

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ANNALS OF THE NEW YORK ACADEMY OF SCIENCES

Vol. XXIII, pp. 193-260, pll. VIII-XV

Editor, Epmunp Ot1s Hovey

THE MANHATTAN SCHIST OF SOUTHEAST-

ERN NEW YORK STATE AND ITS

ASSOCIATED IGNEOUS ROCKS

CHARLES REINHARD FETTKE

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Shen 2B

Fis,

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Ef NEW YORK

PUBLISHED. BY THE ACADEMY

30 ApRIL, 1914

THE NEW YORK ACADEMY OF SCIENCES

(Lyceum oF Naturat History, 1817-1876)

OFFICERS, 1913

President—EMERSON McMitturn, 40 Wall Street

Vice-Presidents—J. EpmMunp Woopman, W. D. MatTrHEw

CHARLES LANE Poor, WENDELL T. BusH

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[ANNALS N. Y. Acap. Sci., Vol. XXIII, pp. 193-260, Pls. VIII-XV. 30 April,

1914]

THE MANHATTAN SCHIST OF SOUTHEASTERN NEW YORK

STATE AND ITS ASSOCIATED IGNEOUS ROCKS?

By CHARLES REINHARD FETTKE

(Presented by title before the Academy, 1 December, 1913)

CONTENTS

Page

ME MRCRIN MET Wee Meet Shs aig) at'5, Sneha o's B/W ove die) on beac eusl d wm ayentotatot eres ate diets 194

IEE IPE CTR Oe Ne ae US os SS su oh ai w SW & ale. wrth «a wor eed Ra eM atgm mcater are 197

NEE URTRE PIES Sere fe Ct. ae, k'0) c.tatn iwiw idiots: aie ue toh, w a3 hue ehn ateie Osea esmaranndte 202

MUIR TESST BIER TERED Ss Fare, as af sci) bot wate s "wt 'w 4g cod w nis @ bre RE ow we 202

MN RR IN EMIS EE ED FREE Zee 5 oR feta 6%, '0).a) a ais Win: ©. wibeh 8 whale vw hdyns ond WW al aoc et ee Nee 203

RNPM IN aT OR ree! S68. ef reld rsd wc, ¥ dislaa's Sete wie yee a he eeiere eels 211

ans BERNE HEIMECCREET OGSTE TONG 92 a ccvcatask % @ mae a lave f us0 le aed a dmc diate ema arte ia aie, ote ee 212

ERIC eos ayo SOS oi 3 ba, 0.014 woe De Me Reena Cees 213

NTE IME TEPET ONES STANCES cae oi cic Yaica 6) 0-5! bee) 6-0 aes se 00 He's eae sa aad mare See eae 216

MPU IMME LSTCr NL ETSIVGS | onic co ate’ eis weld w o's ove cu oa div als shame cteeam en onee 216

Pree OIE RAINING he Se GES ahs oS aja Nialelh sins we a 6 ahi wp elena via ain 216

Actinolite and tremolite schists and associated types............ 219

Pa Me OTAnOGIOLILe SNCISS s <s..00 i'n oe a se aes ce ueldeda amewatneca 220

Origin of hornblende schist and granodiorite gneiss.............. 224

ae aa tea hel Sem ATS TEDL OS <2, is avenaieie tases c fae oa. acc, nn: 0 ete seh eye ohd a wie ata Ore Wake « 220

Reprireree ta ME Ter ooo oe oa se eicics ek mie 0 ui ard w Oem wets eheree afalarneeerera Bie 227

Serer HETIONCNO ILC. 5.0% Soe aiele s 0 0's vole Jute oe ble mbes 228

Miatite Gikes mM nesvicinity Of Bedford :..:. <i. 2 civeliiwfs eee meee ee 231

SEC UT BLVE te RMR AAR re le MOM bras Send «oi pee wat 232

Eee’ WIOEI VTEC c.f oic a %,erwlosee crore vane w alece od Oe Wralne wee meee ae 233

eR SR REPT TIE SP UNES crs ne CK Acc cheba nicl one Sau te ate, cia tele a wor eaten wim kacmeee Mechele 234

Sas aa peR totes OTE NAT EG Os irs ee ale Go ote cae vai Ae a chine ns'e alates cae ata a aetareaie'e 234

tel tess A ETA EILONG, chak)a)o 64.8. ble eb w sine eas anit ned oct aaw se sec eee ee 235

eer REC ee PUR EOT ot SIUC IB 2 ie aiorei ste ce hs im Weis We a <1 a Rts ave mes a) o' a ove draw mie 239

Oecurrence of zeolites in Manhattan sehist... oc. cc... 6 ccs ves eieine 243

EA 2 Sac CE ee ER CS ee ha oe ae ea 244

DS TTS Et ig a A ee ot Sd Fol gE reg ce 245

Peuenduas-wy appinzer-Hudson River S€TICS. 2... ccc wesc eee nse accu eee es 246

emma NEN NOT eerneg TEE ELE GID Wing cl otSeu) = G's aieisielsolsie! sete asd oe 6Viswielele od ob eiheie Noe 247

eae UR AT TEER CIRMBECTERD TNCs se. faecal a2 8 e.o Gave win e:w-alw wid sitly a tales# mle O.GlkLe ie eM 247

PRggeithonivier Slates, DHY INES ANG SCHISIE. ....5. 6 occ c ad cae ns eindeciee 248

eaeh aOR INANE REA TAMRON atta Mra ed Chive ou alk cniat s: 3) shacnnt Noid oh + WG-4 Ww Oahere OR Wal 252

Comparison of Inwood-Manhattan and Poughquag-Wappinger-Hudson

et eaeeat Cervera ese ee a UR. eG ne eae uatea giles deiatamec awe 254

er PP CtO ce MUIR tse I oa Sea Ac glee ich 6, b-a ck reek bk we SO Bid des Veo caswet wemue 258

1 Manuscript received by the Editer, 1 December, 1913. (193)

194 ANNALS NEW YORK ACADEMY OF SCIENCES

INTRODUCTION

The Manhattan schist is the uppermost or youngest of the three crys-

talline metamorphic formations which constitute the bedrock over the

southeastern portion of New York State. The other two are the Inwood

limestone and Fordham gneiss. ‘These three formations are well ex-

posed at numerous localities in New York, Westchester and the southern

portions of Putnam Counties. The overlying mantle of Glacial drift,

seldom very thick, has been removed over many portions of the area by

erosion and in other places was never laid down. ‘To the north, in Put-

nam and Dutchess Counties, the upper two formations, the Inwood lime-

stone and the Manhattan schist, are not present, since a belt of gneisses

constituting the Highlands of the Hudson intervenes. hese gneisses

are probably the equivalent of at least a portion of the Fordham gneiss of

the region to the south. The overlying formations have here been re-

moved by erosion. North of this belt a quartzite appears resting uncon-

formably upon the gneiss. It is followed by a limestone and a slate.

The oldest of these formations exposed in southeastern New York

State, the Fordham, is a black and gray banded gneiss made up largely of

quartz, feldspar and biotite, with occasional grains of zircon and a very

little apatite and titanite. Hornblende is occasionally abundant. Garnet

is rare. The feldspar consists mostly of microcline and orthoclase, to-

gether with some albite-oligoclase. The rock shows a typical gneissoid

structure, the alternate light and dark bands, which rarely exceed one

or two inches in thickness, being due to the concentration of the mica

along certain bands. A few thin beds of highly crystalline limestone are

found associated with the gneiss. Dr. Charles P. Berkey? was the first to

call attention to the fact that these are an integral part of the formation.

The presence of interbedded limestone indicates the sedimentary origin

of at least a portion of this formation. Dr. Berkey has shown that a fur-

ther subdivision of these basal gneisses is impracticable. He correlates

them with the Grenville series of the Adirondacks and Canada, which are

known to be of pre-Cambrian age. Associated with them are a large

number of igneous intrusive masses whose composition varies from that

of granite to that of diorite. Most of these intrusives have also been

subjected to metamorphic agencies so that they now appear as gneisses.

A quartzite occasionally appears in the upper portions of the Fordham

eneiss to which the name Lowerre has been given, since it is from that

1“Structural and stratigraphic features of the basal gneisses of the Highlands.’”’ N. Y.

State Mus. Bull. 107, pp. 361-371. 1907.

FETTKE, MANHATTAN SCHIST OF NEW YORK 195

locality just north of the New York City limits that it was first described,

This quartzite can be studied well at Sparta, a mile south of Ossining

along the New York Central Railroad tracks, and also just east of Hast-

ings-on-Hudson. It seldom exceeds one hundred feet in thickness and

apparently grades into the underlying gneiss. None of the outcrops can

be followed for any considerable distance laterally and they are not of

common occurrence.

The Inwood limestone follows the Fordham gneiss, but in some locali-

ties a thin bed of quartzite intervenes, as is mentioned above. Typically,

this limestone is rather coarse-grained and crystalline, reaching a maxi-

mum thickness of about eight hundred feet. Locally, where the original

limestone was impure, tremolite and diopside occur in it and certain beds

are quite micaceous, containing large amounts of phlogopite. Much of it

runs high in magnesia and grades into a dolomite, but comparatively pure

limestone beds are also present.

The exact nature of the contact of this limestone with the underlying

_ gneiss affords a problem which is difficult to solve. Apparently, the bed-

ding planes of the limestone are parallel to the banded structure of the

gneiss, and, if this banded structure represents the stratification planes

of former sediments from which the gneiss was derived, it would appear

that no marked unconformity exists between the two. This relationship

has been particularly well brought out by the contacts in the tunnels of

the Catskill aqueduct across the formations. In the tunnel underneath

the Harlem River just below High Bridge, no deviation from parallelism

in the banding of the gneiss and the bedding of the overlying limestone

at the contact, which is a sharp one, could be detected. No quartzite is

present here, but a thin seam of pegmatite occurs along the contact. It

seems that a slight amount of faulting movement has taken place along

the contact, which would naturally be a weak zone, but no brecciation

could be detected. A short distance beyond this contact, a bed of light

gray gneiss several feet thick was encountered in the limestone. Its

foliation is also parallel to the bedding of the limestone.

Under the microscope (Pl. XII, Fig. 1), this gneiss is seen to be made

up largely of feldspar, quartz and mica. The feldspar is largely micro-

cline, with some orthoclase and plagioclase present. Biotite is the most

prominent mica present, only a little muscovite appearing now and then.

The biotite is a deep brown variety showing intense pleochroism from

light yellow to deep brown. Occasional minute rounded grains of zircon

and isolated calcite crystals were noticed. The mica shows more or less

parallel orientation, thus giving the rock its gneissoid structure, while the

feldspar and quartz occur in interlocking grains of medium texture and

uniform size.

196 ANNALS NEW YORK ACADEMY OF SCIENCES

The contacts of this gneiss with the limestone are quite sharp, but

nevertheless it can only be interpreted as a recrystallized interbedded

clastic sediment apparently of about the composition of an arkose.

The underlying Fordham gneiss has a light gray color and a distinctly

gneissoid structure, being made up of a series of alternating hght and

dark bands. On the hill just east of the Harlem River in this vicinity, it

is very intricately folded and contorted. Under the microscope (PI. XII,

Fig, 2), it is seen to be made up largely of feldspar, quartz and mica.

The feldspar is mostly microcline, although some orthoclase and plagio-

clase are also present. The mica is for the most part a deep brown biotite

with some muscovite. A little sericite occurs as an alteration product

derived from the feldspar. Cataclastic structure is well developed. ‘The

feldspar and quartz grains are, therefore, not uniform in size and are

usually elongated parallel to the foliation.

The difference in structure between this gneiss and the interbedded one

is probably due to the fact that the limestone on either side of the inter-

bedded gneiss protected it from the intense crushing effect of the forces

accompanying the dynamic metamorphism which developed the cata-

clastic structure in the underlying gneiss and, therefore, only simple

recrystallization occurred.

The same relation between the underlying gneiss and the limestone was

shown in a similar tunnel through these formations near the lower end of

Manhattan Island and also in the excavations for the dam at Kensico.*

The Inwood limestone is succeeded by the Manhattan schist. This

consists essentially of a coarse, quartz-mica-feldspar schist which repre-

sents a recrystallized sedimentary rock of more or less argillaceous com-

position. As would be expected in such a formation, there is considerable

variation from place to place and even in the same outcrop. At the con-

tact, the limestone frequently grades into the schist. The beds of schist

are also interbedded with the limestone and vice versa. Associated with

the mica schist are certain other types of rock, some of which are schists,

others gneisses, while still others are massive. They are undoubtedly of

igneous origin. In composition, they range from very siliceous to very

basic types. Their relation to the schist is such that it appears quite evi-

dent that they were intruded into it in part previous to, in part during,

and in part after the period of metamorphism. It is to a description of

the Manhattan schist and its associated igneous rocks that this paper is

mainly devoted.

All of these formations have undergone intense metamorphism and

have been folded into a series of steep anticlines and synclines, which are

* Oral communication by Dr. Charles P. Berkey.

FETTKE, MANHATTAN SCHIST OF NEW YORK 197

usually unsymmetrical and frequently are overturned toward the west.

The axes of the folds have a general northeast and southwest trend and

usually have a gentle pitch toward the southwest. As a result of later

planation through erosion, the formations are now exposed in a series of

fairly parallel belts running nearly northeast and southwest. The lime-

stone belts on account of their easier erosion are usually carved out by the

valleys. Of the other two formations, the Fordham gneiss is the most

resistant one, but usually the outcrops of both these formations are marked

by ridges. Faulting in two directions, parallel with the folds and across

them, has occurred. This has complicated their exposures. The lime-

stone which normally should appear between the schist and gneiss has at

times been cut out entirely or else its apparent thickness has been con-

siderably reduced.

HISTORICAL REVIEW

Since the region underlain by the Manhattan schist was explored and

settled long before the science of geology had begun to attract any atten-

tion in this country, we find references made to the local formations as

soon as men began the study of geology in North America.

One of the earliest references to the Manhattan Schist appeared in

P. Cleveland’s “Elementary Treatise on Mineralogy and Geology,” which

was published in 1816. Init H. H. Hayden called attention to a granite

ridge which crossed Manhattan Island, appeared again at Hurlgate on

Long Island and then extended into Connecticut. This ridge is now

known to have been merely a protruding portion of the Manhattan schist

which underlies the greater part of the island. William Maclure’s first

geological map of the United States appeared in the same volume. He

placed the rocks underlying Manhattan Island in his primitive formation.

Among other of the earlier discussions on the geology of southeastern

New York is that of Samuel Akerly,* who described the formations under-

lying Manhattan Island and Westchester County in 1820. Akerly recog-

nized granites, gneisses, schists and limestones, all of which he placed in

the Primitive formation on account of their crystalline character and

absence of fossils.

L. D. Gale® in 1839, in his account of the geology of New York County,

described the rocks as consisting chiefly of gneisses and associated serpen-

tine, hornblende, primary limestones and anthophyllite rock.

4An essay on the geology of the Hudson River, and the adjacent regions, illustrated

by a geological section of the county, from the neighborhood of Sandy Hook, in New Jer-

sey, northward, through the Highlands in New York, towards the Catskill Mountains.

New York, 1820.

5“Report on the Geology of New York County.’”’ Third ann. rept. Geol. Surv. New

York, pp. 177-199. 1839.

198 ANNALS NEW YORK ACADEMY OF SCIENCES

W. W. Mather, who was working on the geology of the first district

comprising the southeastern portion of the State, also began the study of

these formations. He published his first article in 1838,° and in his final

report in 1843 on the geology of the first geological district for the New

York survey gave the first comprehensive discussion of the geology and

relationship of the Poughquag-Wappinger-Hudson River series and the

Inwood lmestone and Manhattan schist to the south. Ue traced the

gray semi-crystalline limestone and overlapping slate north of the High-.

lands through their various stages of metamorphism into the white and

gray crystalline limestones and mica schist to the east. The more crystal-

line Inwood lmestone and overlying Manhattan mica schist with asso-

ciated hornblende schist and granite intrusions to the south of the High-

lands, he considered the equivalent of the above series, but in a more

highly metamorphosed phase.

Another paper published about this time, dealing with the geology of a

portion of this region, is one by Issachar Cozzens® on the geological his-

tory of Manhattan Island. He divides the formations of the island into

the following series: Granite, syenite, serpentine, gneiss, hornblende

slate, quartz rock occurring as veins, primitive limestone and diluvium.

A map accompanying the report shows the distribution of these different

formations. The relationship of the formations to one another is indi-

cated by a number of cross-sections. Cozzens conceived the island to be

underlain by a huge batholith of granite from which the granite dikes

radiated out.

In 1867, R. P. Stevens,® in his paper on the geology of New York

Island, proposed the name “Manhattan Group” for the formations under-

lying the island which he believed to be the equivalent of Emmons’s old

Taconic system, now known to represent Cambrian and Ordovician strata

that have been highly metamorphosed. Stevens considered the granite

dikes which are so numerous on the island to be of metamorphic origin,

the same as the gneiss itself. The same applies to the hornblende, antho-

phyllite and other masses of rock frequently found. He thought that

they represented simply different conditions of the same elementary ma-

terial as the gneiss, which had merely undergone different forms of

metamorphism.

®°“Report of the geologist of the first geological district of the State of New York.’’

Second ann. rept. Geol. Surv. New York, pp. 121-183. 1838.

7 Geology of New York, Part I, comprising the geology of the first geological district.

Albany, 1843.

8A geological history of Manhattan or New York Island, together with a map of the

island and a suite of sections, tables, and columns for the study of geology. New York,

1843.

®*“Report upon the Past and Present History of the Geology of New York Island.”

Annals N. Y. Lyc. Nat. Hist., Vol. VII, pp. 108-120. 1867.

FETTKE, MANHATTAN SCHIST OF NEW YORK 199

In 1878, Professor J. S. Newberry’® stated that it was his opinion that

the formations underlying Manhattan Island were Laurentian in age,

although he was not in a position to make a positive assertion to that

effect. The fact that a mottled serpentine’ occurs on Manhattan Island

which very closely resembles the Moriah marble of the Adirondacks which

is known to be of Laurentian age he regarded as very strong evidence of

the pre-Cambrian age of the former.

- The most important contribution, however, to our knowledge of the

formations of southeastern New York State after Mather had published

his final report on the first geological district was the result of the work

done by Professor James D. Dana in this region during the 70’s. In 1880

he published a paper’? on the geological relations of the limestone belts

of Manhattan County. After a careful and detailed study of the lime-

stone belts both to the north and to the south of the Highlands, he came

to the conclusion that they were of the same age. He states that the

limestones and adjoining schists of Westchester County are younger than

the Highland Archean and are probably Ordovician and in part Cambrian

in age. He considers that Westchester County was topographically the

southern part of the Green Mountain elevation, the axis passing along the

Connecticut-New York boundary line and extending through Manhattan

Island. He also pointed out that the grade of metamorphism followed

the same rule south as north of the Highlands, being of greatest intensity

to the south and eastward, since the limestones and associated phyllites

northwest of Peekskill were the least metamorphosed of those occurring

south of the Highlands, while those of the central and eastern portions of

the county and in the western part also were usually very coarsely crystal-

line. The limestones at Verplanck and Crugers on the other hand have

only a moderately crystalline texture. They occupy an intermediate posi-

tion between the least crystalline and the more coarsely crystalline areas,

James Hall in his report on the building stones of New York State?®

in 1886 followed Dana and correlated the marbles quarried in West-

chester County and those of Dutchess County, western Connecticut and

Massachusetts and Vermont. He placed them in the Quebec group.

Professor James F. Kemp in a paper on the geology of Manhattan

10 “The geological history of New York Islands and Harbor.’”’ Pop. Sci. Mthly., Vol. 13,

pp. 641-660. 1878.

a Trans. N. Y. Acad. Sci., Vol. I, pp. 57-58. 1881-82.

2*On the geological relations of the limestone belts of Westchester County, New

York.”” Amer. Jour. Sci., 3rd ser., Vol. 20, 1880, pp. 21-32, 194-220, 359-375, 450-456;

Vol. 21, 1881, pp. 425-443; Vol. 22, 1881, pp. 103-119, 313-315, 327-335.

18*‘Report on building stones.” 39th ann. rept. N. Y. State Mus. Nat. Hist., pp. 186-

225. 1886.

200 ANNALS NEW YORK ACADEMY OF SCIENCES

Island** in 1887 described the formations underlying the island, with a

discussion of their mineralogical composition, origin and structural rela-

tionships.

During the late 80’s, Dr. F. J. H. Merrill did much field work for the

New York State Survey and the United States Geological Survey in the

southeastern part of the State both in the Highlands themselves and in

the metamorphic area to the south. In his first paper*® in 1890 on these

formations, he describes, under the term “Manhattan Group,” the Man-

hattan schist, Inwood limestone, and Fordham gneiss, and states that he

is in doubt as to whether to place this group in the pre-Cambrian or to

correlate it with the slates, limestones and quartzites of Ordovician and

Cambrian age north of the Highlands. The fact that there is a marked

unconformity between the lower Cambrian quartzite and the pre-Cam-

brian gneiss north of the Highlands and that no such unconformity has

yet been found between the Manhattan Group and the underlying beds

south of the Highlands would seem strong evidence against such a corre-

lation. On the other hand, he points out that no unconformity has yet

been found between the partly metamorphosed strata of Peekskill Hollow,

Tompkins Cove and Verplanck’s Point, which he considers to be of Ordo-

vician age, and the metamorphic beds of the Manhattan group which

adjoin them, although such an unconformity would be expected if the

latter are of pre-Cambrian age. In a later report’® he makes the state-

ment that the two series are equivalent, basing his conclusion on the rela-

tion of the quartzite, limestone and schist of Westchester County to the

underlying gneiss, as this relation is precisely similar to that of the Paleo-

zoic strata in southern Dutchess County and Putnam County to the sub-

jacent gneiss, and from the nearly complete stratigraphic continuity.

This statement apparently is contradictory to the one made in the previ-

ous paper quoted, where attention was called to the fact that there was a

marked unconformity north of the Highlands, while none such had been

found to the south. The Fordham gneiss of the Manhattan group, as

previously defined, is considered to be pre-Cambrian in age, possibly Al-

gonkian. The break between it and the Paleozoic is thought to be marked

by a stratum of thinly bedded quartzite which crops out occasionally and

is followed by the Inwood Limestone.

1%“The geology of Manhattan Island.” Trans. N. Y. Acad. Sci., Vol. VII, pp. 49-64.

1887.

15 “On the metamorphic strata of southeastern New York.’”’ Am. Jour. Sci., 3rd ser.,

Vol. XXXIX, pp. 383-392. 1890.

16h J. H. MeRRILL: “The geology of the crystalline rocks of southeastern New York.”

50th ann. rept. N. Y. State Mus., Vol. I, pp. 21-31. 1896.

FETTKE, MANHATTAN SCHIST OF NEW YORK 201

Merrill’s correlation was quite generally accepted as the correct one

until 1907, when Dr. Charles P. Berkey*’ published a paper on the basal

gneisses of the Highlands, based upon field work done by him in the

Tarrytown and West Point quadrangles. He does not accept the correla-

tion of Merrill and others and presents very strong evidence that the

Inwood-Manhattan series south of the Highlands and the Poughquag-

Wappinger-Hudson River series, to the north, are not equivalent. Ac-

cording to his position there are then the following six formations in

relative order from the top downward overlying the basal gneisses :

(6) Hudson River phyllite or slate, which is very thick.

(5) Wappinger fine-grained blue and white banded limestone, about one thou-

sand feet thick.

(4) Poughquag fine-grained quartzite, three hundred to six hundred feet thick.

(3) Manhattan coarsely crystalline mica schist, which is very thick.

(2) Inwood coarsely crystalline limestone, two hundred to eight hundred feet

thick.

(1) Lowerre thin schistose quartzite, zero to one hundred feet thick.

The Lowerre quartzite south of the Highlands is closely related to the

underlying gneiss, whenever it appears, which is not very frequently. It

is thin when it does occur, rarely exceeding one hundred feet in thickness,

and is always conformable with the associated gneiss. The Poughquag

quartzite north of the Highlands on the other hand is usually much

thicker, three hundred to six hundred feet, and rests with a marked uncon-

formity upon the underlying gneiss. The relationship of these forma-

tions in the region northeast of Peekskill in the Peekskill Creek and

Sprout Brook Valleys led Dr. Berkey to conclude that the two series could

not be regarded as the same in age. The quartzite-limestone-phyllite

series of the Peekskill Valley section he considers to belong to the Pough-

quag-Wappinger-Hudson River group, representing a down-faulted block

of these once overlying formations into the older strata. A mile to the

northwest across a ridge another belt of limestone occurs in the Sprout

Brook Valley. This limestone is coarsely crystalline in contrast with the

finely crystalline limestone of the Peekskill Creek section and contains

silicate minerals and pegmatite intrusions which are absent in the latter.

No quartzite whatever occurs in either margin of it, while the Peekskill

Creek limestone has five hundred feet of quartzite conformably beneath it.

The limestones of these two valleys can hardly be considered the same,

and, if the Sprout Brook limestone is the equivalent of the Inwood, as

Dr. Berkey thinks, the less metamorphosed Peekskill Creek limestone is

i “Structure and stratigraphic features of the basal gneisses of the Highlands.” N. Y.

State Mus. Bull. 107, pp. 361-378. 1907.

202 ANNALS NEW YORK ACADEMY OF SCIENCES

clearly shown to be of later age and the Inwood limestone-Manhattan

schist series cannot be the equivalent of the Wappinger limestone-Hudson

River slate series, represented here, but must be of earler age and hence

pre-Cambrian.

There are, therefore, at present two contrasting views: first, that the

Inwood limestone and Manhattan schist series is of Cambro-Ordovician

age, as held by Merrill, Dana, Mather and others; and second that it is of

pre-Cambrian age, as held by Dr. Berkey. The present writer has made a

rather detailed, study of the Manhattan schist and its associated rocks as

developed in the southeastern portion of the State of New York south of

Highlands and has compared it with the Hudson River slates, phyllites

and schists north of the Highlands to see what light such a study might

throw on the problem from a petrographic standpoint. Typical localities

were studied in detail and most of the areas of schist exposed were visited.

A detailed structural study, however, involving very careful geologic map-

ping of large portions of the area underlain by these formations was not

attempted.

MANHATTAN SCHIST

AREAL DISTRIBUTION

The Manhattan schist is exposed in a series of fairly broad, roughly

parallel belts having a general northeast-southwest trend in the region

south of the Highlands of the Hudson and east of the Hudson River (see

map, Pl. XV). West of the Hudson River the Newark formation of

Jura-Triassic age has concealed them with the exception of a small area

in the vicinity of Tompkins Cove just south of the Highlands. The

belted nature of the outcrops of this and the underlying formations, as

has already been explained, is due to the erosion of a series of anticlines

and synclines whose axes have a northeast-southwest trend. The schist

occurs as far north as the southern portion of Putnam County in this

area. Farther north the rest of Putnam and the southern portion of

Dutchess County are underlain by the older gneisses of the Highlands,

the younger formations having been entirely removed by erosion. The

use of the term “‘Manhattan” has been confined entirely to those schists

which make up the uppermost or youngest of the bedrock formations oc-

curring in southeastern New York State in New York, Westchester and

Putnam Counties. In Connecticut the continuation of the schists has

been described under the name of “Berkshire,” as given to them by the

Connecticut Geological Survey.'§

18 Conn. Geol. and Nat. Hist. Surv. Bull. No. 6, pp. 91-92. 1906.

FETTKE, MANHATTAN SCHIST OF NEW YORK . 203

PETROLOGY

The Manhattan schist as typically developed on Manhattan Island con-

sists chiefly of a dark coarsely crystalline mica schist. In a hand speci-

men biotite, muscovite, quartz, feldspar and some garnet can usually be

recognized. The relative amounts of these different minerals in a par-

ticular specimen will vary greatly from place to place. In some cases, the

micas greatly predominate over the other constituents, and the rock often

shows a crenulated structure where it has undergone intense folding and

crumbling. Often considerable amounts of feldspar are: present, but in

other cases, this constituent is almost entirely absent. Garnet is also more

abundant in one place than another. In occasional seams, the rock. is

made up largely of quartz and feldspar with only a little mica in small

flakes. The rock takes on a gray color and is less coarsely crystalline, the

structure becoming gneissoid rather than schistose. Some of these grade

almost into a quartzite, as the amount of feldspar present grows less. On

Manhattan Island, however, the micaceous varieties are greatly in excess

over the others.

A thin section made from a typical specimen of the micaceous variety

taken from the site of the Journalism Building of Columbia University,

at the southeast corner of West 116th Street and Broadway, shows under

the microscope a coarsely crystalline texture and marked foliated struc-

ture (Pl. XIII, Fig. 1). The chief minerals present are biotite, musco-

vite, feldspar, garnet and a little quartz. Magnetite is fairly abundant

and small amounts of pyrite are also present. Several grains of staurolite

have been noticed. The biotite is a dark greenish-brown, intensely ple-

ochroic variety. It is practically always oriented with its basal plane in

the plane of schistosity, to which cause the foliation of the schist is prin-

cipally due. Muscovite is not nearly as prominent as the biotite. It is

often intergrown with it and shows a similar orientation in the plane of

foliation, The space between the micas is occupied by the feldspar and

quartz. The outlines of these minerals are quite irregular and they are

closely interlocked. They are usually quite free from inclusions. Plagio-

clase is the most abundant feldspar present, although some orthoclase also

occurs. The plagioclase is optically positive and belongs to the andesine

variety. It has a maximum extinction angle of 20° in sections cut. per-

pendicular to the albite lamelle. The garnet is a light pink variety oc-

curring usually in idiomorphic crystals which reach a diameter of 1.4

millimeters. Analysis 1 quoted in a later paragraph gives the chemical

composition of this specimen.

204 ANNALS NEW YORK ACADEMY OF SCIENCES

A thin section of the light gray gneissic variety from Shaft 18 of the

Catskill Aqueduct at West 42nd Street near Fifth Avenue, where it occurs

in a belt about two feet wide interbedded with the typical micaceous type,

on the other hand shows a medium-grained crystalline texture and only

slightly foliated structure (Pl. XIII, Fig. 2). The principal constituent

minerals are quartz, feldspar and biotite. Apatite is present in appre-

clable amounts in minute lath-shaped crystals. The feldspar consists of

both orthoclase and plagioclase. The latter has a maximum extinction

angle of 22° in sections at right angles to the albite lamelle and is opti-

cally positive. It is evidently andesine. Both the quartz and the feldspar

occur in allotriomorphie, interlocking grains. The biotite is a dark green-

ish brown, intensely pleochroic variety. ‘The chemical composition of this

type of schist is given under analysis 2 on page 212.

Closely related to the gray gneissoid variety just described is a type

occasionally found in which the amount of feldspar is very small, the pre-

dominant mineral being quartz, so that the rock practically becomes a

quartzite. A section of a specimen from West 155th Street and Tenth

Avenue shows a medium-grained crystalline texture and slightly foliated

structure. The rock is made up largely of quartz with some feldspar and

biotite. Magnetite and a little apatite are also present. The biotite oc-

curs in small, usually irregular flakes whose basal sections are oriented

parallel to the plane of foliation. It shows marked pleochroism from

light greenish yellow to deep greenish brown. The quartz and feldspar

occur in allotriomorphic, closely interlocking grains. The feldspar con-

sists of both orthoclase and plagioclase. The latter shows extinction

angles up to 8° in sections at right angles to the albite lamelle and is

probably oligoclase.

Another variety which has a comparatively fine crystalline texture and

shows only moderate foliation has the biotite occurring in numerous small

flakes showing parallel orientation in a matrix of quartz and feldspar.

The rock has a dark color. A specimen collected two and one-half miles

north of New Rochelle along the Westchester Railroad when examined in

thin section under the microscope shows the rock to consist mostly of

quartz, biotite and feldspar and minor amounts of pyrite, magnetite and

npatite. The biotite is a dark reddish brown variety showing intense

pleochroism from light yellowish brown to deep reddish brown. The

quartz and feldspar occur in allotriomorphic, interlocking grains. Both

orthoclase and plagioclase feldspar are present, the latter giving extinc-

tion angles running as high as 39° in sections at right angles to the

albite lamelle. ‘This would indicate labradorite.

FETTKE, MANHATTAN SCHIST OF NEW YORK 205

The schist in the vicinity of New Rochelle and northeast of that point

becomes for the most part very feldspathic in composition and takes on a

gneissoid structure. A thin section from a specimen collected east of

Pelhamville shows a medium-grained crystalline texture and foliated

structure. The principal minerals are feldspar and quartz in allotrio-

morphic, interlocking grains, together with smaller amounts of biotite

and muscovite. A little apatite is present as needle-like inclusions in the

feldspar and quartz. An occasional grain of zoisite, a little magnetite

and a few rounded grains of zircon also occur. The feldspar which is the

most abundant mineral present consists of both orthoclase and plagioclase.

The plagioclase is an andesine variety, being optically positive and show-

ing extinction angles up to 10° in sections at right angles to the albite

lamelle. The biotite occurs in small flakes whose basal sections are in the

plane of foliation. It shows marked pleochroism from light brownish

yellow to deep brown.

Farther northeast, in the vicinity of Rye, most of the Manhattan schist

formation becomes very quartzose in composition. Alternating with the

thicker beds of quartzitic schist are thinner seams which are more mica-

ceous and hence show foliation to a much more marked degree. The

quartzitic schist has a light gray color and a medium-grained texture.

Examination under the microscope shows that it is made up largely of

irregular interlocking grains of quartz and minor amounts of feldspar,

mostly plagioclase of an oligoclase-albite variety, giving extinction angles

up to 8° in sections at right angles to the albite lamelle and being opti-

cally positive. Some biotite of a deep greenish brown variety and a little

muscovite are also present. A few minute rounded grains of zircon may

be seen.

A gneissoid to schistose quartz-mica-feldspar rock probably belonging

to the Manhattan schist formation occurs in the east central portion of

Westchester County. It has been considered a part of this formation by

F. J. H. Merrill’? in mapping the lower Hudson sheet for the New York

State Survey and also by Edson 8. Bastin,?° who examined the pegmatites

occurring in it at Bedford Village. Lea M. Luquer and Heinrich Ries,”

who have also made a study of the area, on the other hand consider it a

part of the Fordham. The writer’s studies in this region were not suffi-

ciently detailed to allow him to make a positive statement, but it seems

most likely from the position of these rocks with respect to surrounding

limestone belts, outcrops of which occur occasionally and which are

19 Geologic map of New York. Lower Hudson Sheet. N. Y. State Mus.

20 Bull. 315, U. S. Geol. Surv., pp. 344-399. 1906.

21 “The ‘Augen’ gneiss area, pegmatite veins and diorite dikes at Bedford, N. Y.”” Am.

Geol., Vol. XVIII, pp. 239-261. 1896.

206 ANNALS NEW YORK ACADEMY OF SCIENCES

undoubtedly a part of the Inwood, that these schists are a part of the

Manhattan formation.

A specimen collected one-half mile southeast of Bedford Village along

the road to Stamford, when examined under the microscope in thin sec-

tion, shows a medium-grained crystalline texture and foliated structure.

The principal minerals present are quartz, feldspar and biotite. Pyrite

and magnetite occur in minor amounts. The feldspar consists of both

orthoclase and plagioclase, the latter showing extinction angles up to 30°

in sections at right angles to the albite lamellae. It is probably an acid

labradorite variety. The feldspar and quartz occur in irregular, fairly

even-sized, interlocking grains. The biotite occurs oriented parallel to

the plane of foliation and shows intense pleochroism from light yellowish

to dark reddish brown. Another specimen collected one mile northwest

of Poundridge shows very little variation in texture, structure or miner-

alogical composition from the above. The plagioclase here shows extinc-

tion angles up to 22° 30’ and is evidently andesine. A light pink garnet

containing numerous inclusions of quartz and biotite is present in con-

siderable amounts.

From the above description it will be seen that the rock is lithologically

very similar to certain types of Manhattan schist occurring quite abun-

dantly elsewhere. In this schist, however, southeast of Bedford Village,

large “augen” of feldspar, usually orthoclase, which reach a length of one

inch or more at times, are locally quite abundant, so that the rock becomes

an “augen” gneiss. A further discussion of these “augen” will be taken

up under pegmatitic intrusions in a later paragraph.

With the exception of the above occurrence of “augen” gneiss at Bed-

ford Village, the schist does not show any petrographic feature essentially

different from those already described from Manhattan Island and the

region immediately to the northwest, until an outcrop occurring just

north of Croton-on-the-Hudson is reached. Following north from this

point along the road to Peekskill one crosses an area of the schist which is

less thoroughly metamorphosed than most of the schists of the same age

occurring to the south and also than those occurring one and one-half

miles further north, in the vicinity of the Cortland intrusions which will

be discussed later. .

Just north of Croton Village, along the above road, the schist has a

dark gray color and very foliated structure. In a hand specimen, it ap-

pears to be made up largely of prominent crystals of biotite imbedded in

a fine shiny matrix consisting mostly of muscovite. Under the micro-

scope, the most prominent mineral is seen to be biotite (Pl. XIII, Fig. 4).

It is a deep reddish brown variety showing marked pleochroism and

usually has its basal section oriented parallel to the plane of foliation but

FETTKE, MANHATTAN SCHIST OF NEW. YORK 207

not always. The fine-textured matrix in which the biotite occurs consists

of muscovite, smaller biotite flakes, quartz and iron oxides. The little

flakes of muscovite and biotite are usually oriented parallel to the folia-

tion and often curve around the larger biotite crystals.

Going north from the above locality the schist seems to show slightly

more severe metamorphism. Garnet and in some cases staurolite become

important mineral constituents. Tourmaline has been introduced. A

specimen collected about one mile north of Croton-on-the-Hudson along

the road is made up largely of a matrix of fine muscovite In which numer-

ous garnet and staurolite crystals are imbedded. Under the microscope,

the matrix is seen to be made up largely of small flakes of muscovite to-

gether with some quartz and a little orthoclase and plagioclase (Pl. XIII,

Fig. 5). Most of the biotite present occurs in much larger flakes than the

muscovite. A light pink garnet and a yellowish brown staurolite are

quite abundant, occurring in idiomorphie crystals. For a chemical analy-

sis of this schist see analysis 3 on page 212. This was the only place

south of the Highlands where staurolite was found as an abundant con-

stituent in the schist. It is only present elsewhere in very small amounts.

The rock here has a little more coarse-grained crystalline texture than

that described above.

Another specimen taken from near the same locality shows upon ex-

amination in thin section under the microscope abundant little lath-

shaped crystals of dark brown tourmaline. The rock is also much more

quartzose and feldspathic. The feldspar is largely plagioclase of an ande-

sine variety, showing extinction angles up to 25° in sections measured at

right angles to the albite lamelle.

North of this area, no schist is again encountered until the southern

margin of the Cortland intrusive series is reached. A belt of gneiss and

limestone intervenes. A specimen of the mica schist from a point one-

quarter mile west of Crugers, not far from the river and a short distance

south of the contact with the diorites of the Cortland series, is seen, under

the microscope, to be made up of biotite, muscovite, quartz and garnet,

associated with small quantities of orthoclase and plagioclase and a little

apatite. The biotite shows marked pleochroism from light yellowish

brown to deep brown. It and the muscovite are often intimately inter-

grown with their basal sections in the plane of foliation. The irregular

interlocking quartz grains are also usually elongated parallel to the schis-

tositv. The garnet is very abundant in small crystals, rarely exceeding a

diameter of .2 millimeter.

The schist northeast of Crugers along the railroad near the contact

shows very much the same structure and mineralogical composition.

Feldspar, mostly orthoclase, is most abundant. Some of the quartz is

208 ANNALS NEW YORK ACADEMY OF SCIENCES

filled with inclusions of rutile needles. Garnet is not as abundant, but it

occurs in somewhat larger grains.

Farther north, an area of schist and limestone undoubtedly belonging

to the Manhattan-Inwood series adjoins the Cortland intrusives on the

west at Verplanck. The schist here has a medium to fine crystalline tex-

ture and a banded rather gneissoid appearance. In thin section under

the microscope, it is seen to consist largely of mica, mostly biotite, al-

though considerable amounts of muscovite, feldspar and quartz (Pl. XIII,

Fig. 3) are also present. Minor amounts of a dark brown tourmaline

also occur. The biotite shows intense pleochroism from light yellowish

brown to deep brown. The feldspar is mostly microcline, which is present

in large amounts. The structure is distinctly foliated, due to the parallel

orientation of the mica and the elongation of the feldspar and quartz

grains.

Another specimen of mica schist which occurs interbedded with the

limestone at Verplanck, when examined under the microscope, proves to

be much less thoroughly recrystallized and metamorphosed than the above.

Abundant irregular flakes of deep brown biotite occur in a very fine-

grained matrix consisting mostly of quartz and sericite.

The schist again appears just north of the Cortlandt intrusive rocks.

Not far from the actual contact near the southeastern corner of the town

of Peekskill, several outcrops occur along the road to Yorktown Heights.

The rock is medium to fine grained in texture and distinctly foliated.

Under the microscope, it is seen to be made up largely of biotite, sericite

and quartz. The quartz grains occurring between the parallel mica flakes

are extremely fine in texture. Another specimen taken from a point

nearer to the actual contact is much more crystalline in its nature and

shows a higher degree of metamorphism. ‘The minerals present are bio-

tite, muscovite, quartz, feldspar, staurolite, garnet and a little sillimanite.

Some dark brown intensely pleochroic tourmaline was also noticed.

North of this area, no further outcrops of true schists belonging to the

Manhattan formation occur, but along the northwestern side of the

Peekskill Creek Valley about two miles northeast of Peekskill a phyllite

appears. A description of this phyllite and a discussion of its relation to —

the Manhattan formation will be taken up in a later paragraph.

Kast and southeast of Peekskill the schists representing the Manhattan

formation become coarsely crystalline again and are more nearly like those

occurring on Manhattan Island. In places a quartzitic variety predomi-

nates. ‘This is made up largely of quartz, with some feldspar, biotite and

muscovite and a little garnet. Some magnetite is also present. The

quartz and feldspar occur in irregular interlocking grains, while the micas

are oriented parallel to the foliation. Both orthoclase and plagioclase are

FETTKE, MANHATTAN SCHIST OF NEW YORK 209

present. The plagioclase shows extinction angles up to 9° in sections at

right angles to the albite lamelle and is evidently a variety of oligoclase.

The garnet occurs in irregular grains at times full of quartz inclusions.

Thin seams of very micaceous type are often interbedded with this

quartzitic variety of schist. These are usually very much crenulated and

contorted, while the quartzitic variety does not show these minor folds.

This micaceous type consists largely of muscovite and biotite, with small

amounts of quartz and a little garnet. The mica flakes curve around the

garnet.

Toward the northeast, the most northerly outcrops of Manhattan schist

occur in the vicinity of Brewster in southeastern Putnam County. Schists

and limestones belonging to the Manhattan-Inwood series are well ex-

posed in a cut about two miles east of Brewster along the New York and

New England Railroad. The schist is rather coarsely crystalline and has

a distinctly foliated structure. In thin section under the microscope, it is

seen to consist principally of feldspar, biotite and quartz, together with a

little tremolite, pyrite and an occasional rounded zircon grain. The

feldspar is mostly plagioclase giving extinction angles up to 24° in sec-

tions at right angles to the albite lamelle. It is probably an acid labra-

dorite. Some orthoclase is also present, since many of the feldspars are

unstriated and optically negative. The biotite shows marked pleochroism

from light yellowish to deep reddish brown. The rock has undergone

considerable strain. Most of the feldspar shows strain shadows and wedge

twins are common. Mortar structure is also developed in the case of some

of the feldspar grains, which are frequently surrounded by a border of

finely granular material.

About one mile south of Brewster along the road to Croton Falls a

quartzite phase of the schist is well developed. The rock here is made up

of quartz, biotite, feldspar and muscovite, with quartz greatly in excess of

the other constituents. Occasionally a light pink garnet is also present.

The quartz is quite free from inclusions. It and the feldspar occur in

interlocking grains usually elongated parallel to the foliation. The bio-

tite is a dark greenish brown, highly pleochroic variety. More micaceous

and feldspathic phases of the schist are also present at this locality, but

the quartzitic type predominates. On the whole, however, the schist in

the vicinity of Brewster is very closely similar to that occurring farther

south.

The relation of the Manhattan schist to the underlying limestone is

well shown in the excavation at present being made for the new Kensico

reservoir dam at Valhalla about two miles north of White Plains in south-

ern Westchester County. The Fordham gneiss, Inwood limestone, and

Manhattan schist occur in their normal order of succession here, the

210 ANNALS NEW YORK ACADEMY OF SCIENCES

gneiss making up the hills on the east, while the schist makes up those on.

the west of the reservoir site, with the limestone occupying the valley be-

tween the two. The,formations all dip steeply toward the west.

A thin section of the Fordham gneiss taken from near the contact with |

the overlying limestone shows a distinctly gneissoid structure. It is made

up largely of feldspar, biotite and quartz, together with a little titanite

and an occasional apatite crystal. The feldspar is largely plagioclase,”

giving extinction angles up to 8° in sections at right angles to the albite

lamelle. It is optically positive and is evidently an oligoclase-albite

variety. The biotite is an intensely pleochroic, deep brown variety. It

occurs in comparatively small crystals, The greater concentration of

these in particular bands gives the rock its gneissoid appearance.

In the limestone, a short distance above the contact with the underly-

ing gneiss, an interbedded layer of gneissoid rock several feet thick oc-

curs. Under the microscope, it is seen to be made up largely of feldspar,

both microcline and orthoclase, diopside, a reddish brown variety of bio-

tite, calcite and a little quartz. Minor quantities of titanite were also

noticed.

As the contact of the limestone with the overlying schist 1s approached,

layers of interbedded schist begin to appear in the limestone. Some of

these are quite garnetiferous. A thin section of a garnetiferous mica

schist occurring at this point, when examined under the microscope, was

seen to consist largely of biotite, garnet, quartz, sillimanite and a little

feldspar, both orthoclase and plagioclase being represented. A few

rounded grains of zircon are also present. The garnet, which occasionally

contains inclusions of magnetite and biotite, is a light pink variety and

reaches a diameter of .5 millimeter. The sillimanite occurs in little

needles in the quartz and also as a fibrous aggregate. It is abundant.’

The biotite is a deep reddish brown variety. The rock contains numerous '

small stringers of pegmatitic material. For its chemical composition see

analysis 4 on page 212. Other varieties of the interbedded schist contain

little or no garnet and are made up largely of a deep reddish brown bio-'

tite, quartz and feldspar, mainly orthoclase. A few small rounded grains

of zircon are usually present. |

The limestone adjoining these layers of interbedded schist is often im-

pure, at times grading into an ophicalcite. A thin section of such an

ophicalcite was found to consist essentially of calcite, serpentine and mus-

covite. The structure of the serpentine shows that it was derived from a

mineral belonging to the olivine group. One piece was found in which a’

few small cores of the original olivine were still left unaltered. It proved

to be optically negative and, therefore, must either be true olivine, with

more than 12 per cent iron, or else the variety monticellite ( Mg Ca SiO,).

FETTKE, MANHATTAN SCHIST OF NEW YORK 211

It was absolutely colorless. The serpentine to which it has altered is also

colorless in thin section and grass green in the hand specimen. No other

minerals occur which would indicate the presence of much iron in the

original sediment from which the ophicalcite was derived, as for example,

phlogopite or biotite. Therefore, it appears probable that the original

mineral was monticellite. |

The true Manhattan schist overlying the limestone at this point is a

feldspathic micaceous variety of medium gray color. Under the micro-

scope, it is seen to consist largely of biotite, muscovite, quartz, feldspar,

mostly orthoclase, sillimanite and a little garnet. A few small rounded

grains of zircon are also present. The rock has undergone considerable

crushing here since the original recrystallization during metamorphism

took place. This is shown by the nature of the broken quartz and feldspar

crystals and to a less extent the mica. The mica also often occurs in bent

crystals. 7 | |

Another variation in the schist’ observed, especially in the southern

portion of the area on Manhattan Island, and not heretofore described,

appears in the form of occasional bands very rich in cyanite. These sel-

dom reach a width of more than an inch or two, and wherever observed

were parallel to the schistosity. At times, these bands are made up en-

tirely of long prismatic crystals of cyanite associated with muscovite and

quartz (Pl. XII, Fig. 3). These crystals are optically negative and show

elongation parallel to the slow ray. Extinction is unsymmetrical. Their

long axes are parallel to the schistosity. These bands grade into the mica

schist in which the cyanite occurs associated with biotite, muscovite, some

garnet and only a little quartz. Thin veinlets of introduced quartz are

usually associated with the bands running parallel to the foliation. A

chemical analysis of this schist is given in a later paragraph under analy-

sis 5 on page 212. | |

| STRUCTURAL FEATURES |

The schist and underlying formations, as has already been mentibned

in the introduction, occur in a series of rather closely folded anticlines

and synclines usually unsymmetrical and often overturned toward the

west. The axes of these folds run in a general northeast and southwest

direction and in many cases have a gentle dip ‘toward the south. In addi-

tion to these major folds, many minor folds are developed in the schist, St)

that at times it becomes exceedingly contorted and crinkled. As is usually

the case in folded rocks of this nature, the axes of these minor folds are

parallel to those of the major ones. | |

Most of the schist, especially the more micaceous varieties, shows a

marked foliated structure. In the case of the more gneissoid varieties,

212 ANNALS NEW YORK ACADEMY OF SCIENCES

this may not be so marked, but a more or less banded structure can always

be made out.

As has already been pointed out in the petrographic description, the

schist shows considerable variation from place to place and even in the

same outcrop. Different varieties may grade into one another gradually,

or the transition may be fairly abrupt. In either case, the schistosity is

always parallel to the bands of varying composition.

The schist and underlying limestone, as shown by the description al-

ready given, grade into one another, and the layers of schist interbedded

with the limestone near the contact have a strike and dip which are parallel

to that of the actual contact of the overlying Manhattan schist with the

limestone. The foliation of the schist near the contact is parallel to the

bedding of the limestone.

The normal relationship of the schist to the underlying beds has fre-

quently been obscured by faulting. In general, these faults have a strike

approximately parallel to the axes of the folds, and when such is the case,

the schist may be brought in contact with the gneiss, as frequently hap-

pens. East and west faults nearly at right angles to the axes of the folds

also occur. Joints are well developed in the schist at many places. A

nearly vertical set cutting across the folds at about right angles is well

developed at several localities on Manhattan Island.

CHEMICAL COMPOSITION

The following analyses of various types of Manhattan schist made by

the writer show the range in chemical composition of some of the differ-

ent varieties present :

Analyses of Manhattan Schist

1 2 3 4 5

SIOY ns5.0 0e/e Gas 46.50 68.51 50.90 45.03 74.14

BUG > ais te 3% seer 24.97 15.68 30.46 33.76 Peete

| 1 Le 0 ee eeretei 080 ba 2.63 Sal 1.36 None 63

WOO” aie accrae as 9.58 2102 4.59 8.19 46

Wes Rp ee S10 1.42 1.09 2ete 19

Cas. atau cso yA Pat 3.83 .93 15 None

Na O.Mratie-ael se SoD 4.62 1.96 222 sat

BESO) ed Base Aenea 4.34 2.49 6.86 4.62 A152,

15 0 ee ary ee avd sie .49 91 By

Oi. ia oA O7 01 .05 16 02

TG, estes scee ate 1.61 ay 1.54 1.2 O8

FETTKE, MANHATTAN SCHIST OF NEW YORK 213

1. Mica feldspar schist from southeast corner of Broadway and West 116th

Street, New York.

2. Gray gneissoid variety from Shaft 18, Catskill Aqueduct, West 42nd

’ Street, near Fifth Avenue, New York.

3. Staurolite mica schist north of Croton-on-the-Hudson.

4. Garnetiferous mica schist, Kensico.

5. Cyanite schist, West 120th Street, east of Amsterdam Avenue, New York.

An examination of these analyses brings out several interesting fea-

tures. In all of these, except No. 2, the MgO is present in excess over the

CaO and the K,O over the Na,O. Also the ratio of Al,O, to the CaO,

Na,O and K,O exceeds the 1:1 ratio in each of these cases. In No. 1,

this excess amounts to 70 per cent; in No. 3, 147 per cent, and in No. 4,

181 per cent. In the case of No. 5, no comparison is necessary, as the

amounts of K,O and Na,O present are practically negligible and CaO is

absent entirely, while the rock contains 23.82 per cent of Al,O,. Such a

relationship as the above could only exist in a rock which was originally

of sedimentary origin.?? The analyses, therefore, give an important clue

as to the origin of these schists.

ORIGIN

As shown above, the analyses of various types of mica schist belonging

to the Manhattan formation, with the possible exception of No. 2, indi-

cate a sedimentary origin for this formation. Analysis No. 1 of the typi-

cal mica feldspar-quartz schist developed on Manhattan Island corre-

sponds to that of a rather argillaceous shale. The same holds true for

Nos. 3 and 4. No. 2, on the other hand, which is that of a gray gneissoid

variety, as far as chemical composition is concerned, might be either of

sedimentary or igneous origin. Its field relation, however, to the associ-

ated typical mica schist is such that it can only be interpreted as being of

the same origin and merely representing a phase of deposition of some-

what different character. The clastic material from which it was derived,

originating from the disintegration of an igneous rock of granitic com-

position, had probably been less thoroughly decomposed and sorted before

deposition took place, therefore giving rise to the deposition of an arkose.

It probably represents a coarser phase of deposition than any of the others

which originally were undoubtedly fine muds.

The variation in texture and composition of the schist both vertically

and horizontally over large areas also permits of but one interpretation,

namely, a sedimentary origin. The occurrence of occasional very quartz-

itic beds grading into pure quartzites furnishes further corroboration

toward this conclusion. The nature of the contact between the schist and

22HDSON S. BASTIN: Jour. Geol., Vol. 17, p. 472. 1909.

214 ANNALS NEW YORK ACADEMY OF SCIENCES

underlying limestone also agrees with such a view. The gradation of the

limestone into schist and the occurrence of thin beds of schist in the lime-

stone near the contact is what one would expect to find when the condi- .

tions favorable for the deposition of a limestone gradually changed toward

those leading to the deposition of an argillaceous sediment. Evidently

the two formations are conformable.

Later, these strata underwent profound regional metamorphism which

led to the complete recrystallization of the constituents present. These

changes were brought about through burial to a considerable depth under-

neath other sediments, followed by the inauguration of a period of great

orogenic movements which brought about the intense folding of the strata

involved. These orogenic movements were accompanied by a series of

granitic intrusives which are described later and which also must have

been important factors leading toward the thorough recrystallization of

the original sediments. Their effect will be discussed in somewhat greater

detail in another paragraph.

The formation of the schist, therefore, took place under mass-mechan-

ical conditions in the zone of ana-morphism, as described by Professor

Van Hise.** If we follow Dr. Grubenmann’s plan of dividing the outer

portion of the earth into three zones, based upon the nature of the meta-

morphic changes taking place at different depths, the formation of the

schist took place in the middle zone. In this zone, as described by Dr.

Grubenmann,** the temperature is notably higher than in the upper zone,

and pressure and temperature alike tend to work toward the production

of such minerals as represent the smallest molecular volumes and highest

specific gravities for the constituent components present. The pressure

is mostly due to stress, although hydrostatic pressure due to the superin-

cumbent mass also begins to become effected. There is little possibility

of any movement of the particles, and stress aided by temperature, there-

fore, works principally toward recrystallization, so that chemical action

not only keeps pace with mechanical but even exceeds it. Wholly crystal-

line rocks are therefore formed in this zone, and good cataclastic structures

are not of common occurrence. On account of the fact that the prevailing

pressure is due to stress, this is the home of the schists. The character-

istic minerals of this zone are muscovite, biotite, zoisite, epidote and to a

lesser extent hornblende, staurolite, garnet and cyanite. Dr. Gruben-

mann’? also calls attention to the well known fact that the higher the

temperature and pressure under these conditions the greater will be the

23 Monograph XLVII, U. S. Geol. Surv., pp. 685-698. 1904.

* Die kristallinen Schiefer. Zweite Auflage, p. 78. 1910.

= TOC Dito:

FETTKE, MANHATTAN SCHIST OF NEW YORK 915

tendency of minerals rich in OH to alter to those lower in OH and finally

to those free from it entirely. Chlorite will be replaced by biotite; zoisite

and epidote by plagioclase, and muscovite, by orthoclase and microcline.

In the case of the Manhattan schist, it has already been seen that

the biotite-quartz-feldspar varieties predominate, although muscovite 1s

usually also present and is frequently an important constituent. These

evidently represent the final stages to which metamorphism will proceed

in this zone. With the exception of the area of schist to the north of

Croton-on-the-Hudson and that in the vicinity of Peekskill far enough

away from the Cortlandt intrusions to be out of range of very much influ-

ence from their contact metamorphic effects, the schists of the region

under discussion have all undergone about the same degree of metamor-~

phism. ;

In the case of the schist just north of Croton Village, it is quite evident

that the fine matrix of muscovite, biotite, quartz and iron oxide in which

the coarser biotite flakes are imbedded, if recrystallization had proceeded

to a further stage, would have been converted into a much coarser mass

consisting of larger biotite crystals, feldspars and quartz, with possibly

some garnet and only a little muscovite. Further north of the same area

of schist where metamorphism has been somewhat more intense, feldspar

does become quite prominent. Staurolite and garnet also become quite

abundant constituents of the schist here. The garnet, as seen from the

petrographic description of the schist from widely distributed outcrops, is

a quite common constituent of these rocks. Staurolite, on the other hand,

is quite rare, this being the only place south of the Highlands where it

was found in any abundance. Apparently with the more severe meta-

morphism which took place to the east and south, it was converted into

other minerals. What has been said in regard to the schist just north of

Croton-on-the-Hudson also applies to the schist occurring near the south-

east corner of the town of Peekskill along the road to Yorktown Heights.

As may be seen from the petrographic description, the minerals present

in the schist are quartz, orthoclase, plagioclase (ranging from oligoclase

to labradorite), biotite, muscovite, garnet, staurolite, sillimanite, cyanite,

magnetite, pyrite, apatite, zircon, zoisite and tourmaline. Of these, all

but the tourmaline have probably resulted from the recrystallization of

constituents already present in the original sediments before recrystalliza-

tion took place. None of these minerals contain components which would

not occur in such a formation as the one from which the schist was de-

rived. The presence of the tourmaline on the other hand is probably due

to the introduction of a least a portion of its constituents, especially the

boron by emanations which accompanied the pegmatitic intrusions re-

ferred to later.

216 ANNALS NEW YORK ACADEMY OF SCIENCES

The thin seams of cyanite schist described as occasionally occurring in

the mica schist on Manhattan Island are sufficiently different from the

ordinary mica schist to deserve further mention. Referring back to

analysis 5, p. 212, which is of such a schist, it will be seen that it is made

up almost entirely of silicaand alumina. If this schist had been derived

from an original sediment, it would mean that there must have been a

very thin layer of practically pure kaolinite and quartz where the thin

seams of cyanite schist now occur. As already mentioned, it hardly ever

occurs 1n seams over one or two inches wide. It is not very probable that

such a remarkable concentration of these two constituents should occur in

such narrow seams when the surrounding sediments were of such entirely

different composition. What seems more probable is that some of the

_more soluble original constituents have been leached out by percolating

waters along these seams, leaving behind the less soluble alumina prob-

ably present in the form of kaolinite, The stringers of introduced quartz

associated with these seams would seem to bear out this theory. ‘They at

least indicate that such circulation has taken place. This circulation of

water along these seams and the introduction of quartz was probably

closely related to the pegmatitic intrusions occurring in the schist which

are discussed later.

ASSOCIATED IGNEOUS RocKS

eur FOLIATED BASIC INTRUSIONS

Hornblende Schist

Intercalated with the mica schist of the Manhattan formation are often

layers of hornblende schist which vary in width from less than a foot up

to two hundred feet or more. These layers may often be followed along

the strike for several thousand feet. Sometimes several of them will

occur parallel to one another and separated by only a slight thickness of

intervening mica schist.

The gradation from hornblende to mica schist is always a sharp one.

The sheets of hornblende schist practically always occur parallel to the

foliation of the schist which has been shown to be parallel to the bedding

(Pl. VIII, Fig. 1). The writer did not come across a case where any

marked deviation from this relationship could be detected, but Dr. Charles

P. Berkey”® has discovered an occurrence in mapping the geology of the

Tarrytown quadrangle where the hornblende schist cut distinctly across

the foliation of the mica schist, and Mr. John R. Healy?’ has observed a

similar case in the Catskill aqueduct under Manhattan Island.

2% Oral communication.

27 Oral communication.

FETTKE, MANHATTAN SCHIST OF NEW YORK ae |

In general, however, as already shown, these sheets run parallel with

the foliation of the mica schist and are just as folded and crumpled as the

latter. At times, the hornblende schist is even more plicated than the

mica schist. This usually occurs where the latter was a rather quartzose

variety. In such a case, the hornblende schist is the more pliant member,

and naturally it was more closely folded.

In a hand specimen, the hornblende schist appears rather massive, show-

ing some foliation, however, and a tendency to cleave in parallel plates.

Its color is greenish black which serves to readily distinguish it from the

lighter colored mica schist. In mineral composition, it consists princi-

pally of a dark green hornblende, together with subordinate amounts of

feldspar, mostly plagioclase, and quartz. Minor accessory constituents

usually present are magnetite, biotite, apatite, titanite, zircon and pyrite.

In some cases, garnet also occurs in it in quite appreciable amounts. This

schist maintains a fairly uniform mineral composition from place to place

without much variation in the percentages of the constituents present.

The hornblende schists are particularly well developed along the south-

ern shores of Croton Lake in the vicinity of the old Croton dam. A thin

section of a specimen taken from an outcrop exposed in a cut a short dis-

tance west of the bridge across the lake at this place when examined under

the microscope is seen to consist largely of dark green hornblende, together

with minor amounts of quartz and feldspar (Pl. XII, Fig. 4). Titanite

is present in considerable amounts. Other accessory minerals are biotite,

magnetite, zircon and apatite. The hornblende is a deep brownish green

variety showing marked pleochroism from light greenish brown through

brownish green to deep green. Prismatic cleavage is well developed. It

often contains inclusions of titanite and apatite. The feldspar and quartz

occur in irregular interlocking grains of comparatively small size. The

feldspar is mostly plagioclase, although some of it is unstriated. It shows

extinction angles up to 16° 30’ in sections at right angles to the albite

lamelle and is optically positive. It is evidently andesine. The horn-

blende crystals show a roughly parallel orientation which gives the rock

its foliated structure. The chemical composition of this specimen of

hornblende schist is given in a later paragraph.

An interesting phenomenon was noticed along a fault plane which in-

tersected, obliquely to the foliation, the sheet of hornblende schist just

described. On both walls of the fault a thin coating consisting of dark

greenish brown biotite flakes was developed. Evidently during the shear-

ing accompanying the fault movement conditions were favorable for re-

crystallization, and the hornblende along the fault was converted into

biotite. A little secondary quartz was also introduced. The hornblende

schist must still have been buried under a considerable thickness of over-

218 ANNALS NEW YORK AUCADEMY OF SCIENCES

lying strata when this took place, as the alteration of hornblende into

biotite requires rather deep-seated conditions.**

Small stringers of pegmatitic material are fairly numerous in the horn-

blende schist at this place. These usually follow the foliation of the

schist, although at times they also cut across it and occasionally widen

out into lenticular or irregular shaped masses. Associated with these

stringers are occasionally found lenticular masses of epidote schist evi-

dently derived by alteration from the hornblende schist. These are sel-

dom more than six inches wide and three or four feet long (Pl. VIII,

Pie. 2).

In thin section, this variety is seen to consist principally of epidote

associated with remnants of the unaltered dark green hornblende. Some

calcite is also present as a secondary product. Quartz appears both in

little irregular shaped grains distributed through the whole mass and also

in, little stringers. ‘The accessory constituents present are magnetite,

titanite and zircon, A chemical analysis of the epidote schist will be

found in a later paragraph. Such a rock is known as an epidosite.

Attention has already been called to the sharp contacts between the

hornblende schist and mica schist. This is very noticeable wherever such

contacts are exposed. Thin sections of the hornblende schist and mica

schist where they adjoin were examined from two parallel hornblende

schist sheets occurring in the mica schist about one and one-quarter miles

northwest of Hartsdale along the road to Elmsford. The lower of these

sheets is about two and a half feet thick, while the upper one is much

thicker but 1s partially covered. Two and one-half feet of mica schist

separate the two. They are involved in a sharp anticline.

The mica schist is a quartzitic variety at this place which has a

medium-grained crystalline texture and foliated structure. It consists

largely of quartz in irregular grains and usually elongated parallel to the

fohation; of a dark greenish brown biotite showing parallel orientation

and a little feldspar, mostly plagioclase; of an occasional small garnet,

and of a few rounded grains of zircon. The hornblende schist is a dark

greenish black rock with a more or less foliated texture. It consists prin-

cipally of a dark brownish green hornblende, together with feldspar and

a little quartz. Accessory constituents are magnetite, zircon, titanite and

zoisite. The hornblende shows marked pleochroism from light brown

through brownish green to dark green. The feldspar is mostly plagio-

clase, giving extinction angles up to 23° 30’ in sections at right angles to

the albite lamelle, thereby indicating an andesine.

Very little difference from the normal was noticeable in these two rocks

i the specimens taken from near the contacts. Occasionally biotite be-

27°C. R. VAN HISE: Treatise on Metamorphism. U. S. Geol. Surv., Mon. 47, p. 290.

1904.

FETTKE, MANHATTAN SCHIST OF NEW YORK 219

came quite an important accessory constituent of the hornblende schist,

but this mineral was present just as abundantly in specimens collected

elsewhere, where they were not taken from the vicinity of any contact.

In the mica schist, however, just above the lower sheet of hornblende

schist, which is the smaller of the two, a dark brownish green hornblende

identical with the one present in the hornblende schist was found in oc-

casional crystals. Such a hornblende was not noticed in any other speci-

mens of mica schist and is not a normal constituent of this rock. Appar-

ently the presence of the hornblende schist explains its occurrence.

Closely related to the hornblende schist is a variety of hornblende or

quartz diorite gneiss which occurs in the mica schist at various places but

not nearly as abundantly as the hornblende schist itself. Its mode of oc-

currence and structural relationship are the same as that of the horn-

blende schist, and sometimes it grades into the latter. Megascopically it

is seen to be made up of alternating light and dark bands, usually less

than an inch thick, which grade into one another.

Such a gneiss occurs about three-quarters of a mile southwest of Mill-

wood along the road to Ossining. The lighter bands, when examined

under the microscope, are seen to consist largely of quartz, feldspar and

hornblende, together with small amounts of biotite. A little garnet is

also present, as well as an occasional zircon. Small amounts of epidote

and zoisite occur as secondary minerals. A somewhat cataclastic struc-

ture has been developed. The feldspar consists of both orthoclase and

plagioclase. The latter is optically positive and shows extinction angles

up to 5° 30’ in sections at right angles to the albite lamellae, which would

indicate an albite-oligoclase. The darker bands owe their color to the fact

that the hornblende becomes much more abundant in them, being the

most important constituent. The other minerals of the lighter bands,

however, are also present but in smaller amounts.

Actinolite and Tremolite Schists and Associated Types

Another type of schist occasionally found interstratified with the mica

schists consists predominantly of actinolite or tremolite. This type is

very similar in its mode of occurrence to the hornblende schist just de-

scribed. A sheet was encountered in the Catskill Aqueduct tunnel just

north of Shaft 18 at Madison Square, New York City. The borders of

the sheet consist of a very coarsely crystalline biotite schist, in which bio-

tite makes up the greater part of the rock. Most of the sheet, however, is

an extremely foliated tremolite schist. When examined in thin section

under the microscope, it is seen to be made up largely of tremolite, biotite

and a little tale. The tremolite occurs in long acicular crystals showing

good prismatic cleavage. Transverse fractures are also well developed.

22() ANNALS NEW YORK ACADEMY OF SCIENCES

The biotite is a deep brown variety with a slight tinge of red. It occurs

sparingly throughout the mass between the tremolite crystals and is also

concentrated in lenticular bunches averaging about .2 x .3 x 1.00 inch in

size, The tale occurs in tabular flakes among the tremolite crystals. In

portions of the sheet, the tale predominates and the rock grades into a

tale schist. Veins of asbestiform amphibole up to two inches in width

have also been developed in places. This amphibole occurs with its long

axis at right angles to the foliation. The tremolite occurs in parallel

orientation with the schistosity. The whole mass shows evidence of havy-

ing undergone intense shearing accompanied by recrystallization of the

constituent minerals into new combinations.

The mass of actinolite and tremolite schist formerly exposed at Eleventh

Avenue and West 59th Street?® is another example of this type. Here

taleose and chloritic varieties, together with serpentine and ophicalcite,

were also present in close association with the actinolitic and tremolitic

varieties.

Harrison Granodiorite Gneiss

Another rock probably quite closely related genetically to the horn-

blende schist described is a granodiorite gneiss occurring in the south-

eastern portion of Westchester County. Its relation to the mica schist is

somewhat similar to that of the hornblende schist, only it occurs in a

much more extensive mass. The strike of the gneissoid to schistose struc-

ture developed in it is parallel to the foliation of the mica schist adjoin-

ing it.

This gneiss is most extensively developed just across the State line in

Connecticut, where it occupies a large area. Two prongs from this mass

extend southwest into Westchester County, New York. The northwestern

one of these is about one and one-quarter miles wide and extends as far

as Larchmont, while the southeastern one is about one mile wide and ex-

tends to Rye Point. An area of schist about one and three-quarter miles

wide separated the two prongs.

Professor Heinrich Ries*® was the first to describe this gneiss from the

vicinity of Harrison.in Westchester County, and it has since then been

generally referred to as the “Harrison granodiorite.” The Connecticut

Survey** on their preliminary geological map of the State, however, have

called it the Danbury granodiorite gneiss, correlating it with similar

gneisses which are quite extensively developed in other portions of west-

ern Connecticut.

2A. A. JULIEN: “Amphibole schists of Manhattan Island.’’ Bull. Geol. Soc. Am., Vol.

14, pp. 421-494. 1903.

*° “On a granodiorite near Harrison, Westchester County, N. Y.’’ Trans. N. Y. Acad.

Sci., Vol. 14, pp. 80-86. 1895.

31 Geol. and Nat. Hist. Surv. Conn., Bull. No. 7. 1907.

FETTKE, MANHATTAN SCHIST OF NEW YORK 221

In a hand specimen, the rock shows a very gneissoid structure and

medium coarse crystalline texture. The principal minerals present are

biotite, hornblende, feldspar and quartz, with the ferromagnesian min-

erals occurring in such large amounts as to give the rock a dark color.

Occasionally “augen” of feldspar are a prominent feature in the rock.

These sometimes reach a length of one inch with a width of one-quarter

inch.

A thin section of a specimen from north of Larchmont in Westchester

County, when examined under the microscope, shows a medium coarse

crystalline texture and foliated structure due to the more or less parallel

orientation of the biotite and hornblende. The section consists largely

of feldspar, hornblende, biotite and quartz. Magnetite, titanite and apa-

tite are present as accessory constituents. The feldspar is largely plagio-

clase, which gives extinction angles up to 26° in sections at right angles

to the albite lamellae and is optically positive. It is evidently an acid

labradorite. Some orthoclase is also present, much of the feldspar being

unstriated. A micrographic intergrowth of feldspar with quartz is occa-

sionally developed. Undulatory extinction in the feldspar and quartz is

of common occurrence.

Another thin section made from a specimen from Greenwich, Connecti-

cut, shows practically the same structure and texture (Pl. XII, Fig. 5).

The mineral composition varies only slightly. Biotite is present in excess

of hornblende. In addition to the plagioclase and orthoclase, some micro-

cline also occurs. An analysis of this rock is given in the next paragraph.

The following analyses of hornblende schist, epidosite and granodiorite

gneiss were made by the writer: |

Analyses of Hornblende Schist. Epidosite and Gneiss

1 2 3

18 See eee 45.90 43 .52 55.71

OR Saar one nied 15.58 16.60 19.15

LEN 0 A acer ere 2.23 GGG" hy igen e

BeCOW Ga etcsees 10.48 4.79 5.81

BIZ O'coisiaw civen Sit 7.02 3.42 4.52

6 8 SEE ee ere es 11.14 19.95 6.42

INOS 2G is oi hie OE 2.47 77 3.55

BOL te etc 1.49 25 4.56

ROR oh dia mar soa’ .20 31 09

BO oases 06 i 06

OS rota wea nien AGN Oc ae NE ere 2

dis (0 Be ee aoe ey! 3.92 75

Potala: <2: 99.98 | 100.71 100.62

929 ANNALS NEW YORK AUADEMY OF SCIENCES

Norms

i 3

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No. 1. Hornblende schist from south shore of Croton Lake. Magmatic sym-

bol, 1II, 4.4.8. Auvergnose. .

No. 2. Epidote schist or epidosite from above locality.

No. 8. Granodiorite gneiss. Greenwich, Connecticut. Symbol II, 5.3.3. She-

shonose. .

In the following table, analyses of massive igneous rocks very similar in

chemical composition to the hornblende schist and granodiorite gneiss are

given for comparison :

223

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924 ANNALS NEW YORK ACADEMY OF SCIENCES

ORIGIN OF HORNBLENDE SCHIST AND GRANODIORITE GNEISS

Dr. A. A. Julien*? in a paper on the amphibole schists of Manhattan

Island has given an excellent description of these rocks and their mode of

occurrence. He has also taken up a detailed discussion in regard to their

origin, and his conclusions have been quite generally accepted as being

correct. He believes that these rocks represent metamorphosed igneous

rocks of rather basic composition which were injected through fissures

and spread out parallel to the bedding planes of the mica schist in the

form of intrusive sheets or sills at a period prior to the folding of the

latter.

The chemical composition of the hornblende schist furnishes very

strong evidence in favor of its igneous origin. It is that of a rather basic

igneous rock. The three analyses of massive igneous rocks, one of a dia-

base, another of a camptonite and a third of a diorite, which are given for

comparison in a previous paragraph, correspond very closely to that of

the hornblende schist. The hornblende schist from Scourie, Scotland, has

a texture corresponding very closely to that of the New York hornblende

schist. The diabase from Scourie, Scotland, has a diabasic texture. In

mineral composition, it consists of feldspar, augite, ilmenite, apatite and

small amounts of such secondary products as hornblende, chloritic min-

erals, quartz and pyrite. The camptonite from Salem Neck, Massachu-

setts, approaches the ophitic texture. ‘The minerals present are horn-

blende, less pyroxene, occasional olivine, a labradorite feldspar, a little

orthoclase and some magnetite and, rarely, apatite. The diorite from

Hump Mountain, North Carolina, contains plagioclase, orthoclase, horn-

blende and minor amounts of quartz, biotite, magnetite and garnet. It is

readily conceivable that rocks of such mineralogical composition upon

undergoing intense dynamic metamorphism could and would be con-

verted into hornblende schist. The augite in the case of the diabase and

camptonite would naturally be converted into hornblende. Olivine would

not be staple under. such conditions and, if present, would disappear,

entering into the composition of some other ferromagnesian mineral.

Another strong point in favor of an igneous origin for the hornblende

schist is the sharp contact always found occurring between it and the

mica schist, with the absence of any signs of gradation of one into the

other. It has already been pointed out that wherever undoubted sedi-

mentary contacts occur in the district no such sharp contacts are found,

as for example, the gradation of limestone into mica schist or one type of

mica schist into another.

32 Bull. Geol. Soc. Am., Vol. 14, pp. 421-494. 1903.

FETTKE, MANHATTAN SCHIST OF NEW YORK 225

If any evidence of contact metamorphism could be found, this would

still further corroborate the igneous origin of the hornblende schist. As

already mentioned, the only occurrence observed by the writer which

might\indicate such a contact zone was the occasional presence near such

a contact of isolated hornblende crystals in the mica schist which were

similar in appearance and optical properties to those of the hornblende

schist.

The relation of the hornblende schist to the mica schist is such as might

readily result from the intrusion of a series of sheets parallel to the bed-

ding of the schist. Such a relation would also result if the igneous rock

had been poured out as a lava flow at successive intervals during the

period of deposition of the sediments from which the mica schist was de-

rived. This would, however, necessitate the occurrence of numerous

periods of igneous activity followed by periods of deposition of fine argil-

laceous sediments, as the sheets probably occur at various horizons in the

schist over practically the whole area under consideration. The same

would be true if they represented metamorphosed interbedded basic tufts.

It is much more reasonable to suppose that the igneous rock was intruded

at numerous horizons in the sediments after their deposition in the form

of intrusive sheets or sills. The fact that the hornblende schist does oc-

easionally cut across the foliation or bedding further corroborates such a

view. The only peculiar feature about the hornblende schist, if the above

interpretation is correct, is that it has never yet, to the writer’s knowl-

edge, been found cutting the Inwood limestone. The probable explana-

tion for this is that the limestone did not part readily along its bedding’

planes and the intrusive simply passed up through it along fissures which

are not at present exposed.

From the foliated structure of the hornblende schist and its relation to

the mica schist, it is quite evident that it was intruded into the original

sediments prior to the period of folding and regional metamorphism.

Both have been folded and crumpled with equal intensity and have been

completely recrystallized. They now possess a marked foliated structure

and a medium to coarsely crystalline texture. J. J. H. Teall** has de-

scribed a similar hornblende schist from Scourie, on the northwest coast

of Scotland, which can be traced through various stages of metamorphism

into an original diabase dike. Analyses of this hornblende schist and

diabase are quoted in a previous paragraph. The hornblende schist is

made up of deep green hornblende, quartz, feldspar, ilmenite, sphene and

apatite. The diabase consists of feldspar, augite, ilmenite, apatite and’

minor secondary products including hornblende, chlorite, quartz and

8 Quart. Jour. Geol. Soc., Vol. 41, pp. 133-145. 1885.

226 ANNALS NEW YORK ACADEMY OF SCIENCES

pyrite. This rock was converted into hornblende schist by mechanical

deformation accompanied by molecular rearrangement of the augite and

feldspar. The changes which resulted in the formation of the hornblende

schist of southeastern New York were probably very similar to those

which have occurred in the case of the Scourie dikes.

The lenticular to tabular shaped masses of epidosite occasionally ob-

served in the hornblende schist associated with small stringers of pegma-

titic material represent an alteration which has occurred since the devel-

opment of the foliated structure, since the remnants of unaltered horn-

blende in the epidosite show the same parallel alignment as those in the

normal schist. The hornblende and feldspar of the original hornblende

schist along these zones have been converted into epidote. This was

brought about by some marked changes in chemical composition, as a

comparison of an analysis of the hornblende schist with one of the epido-

site developed from it will show. Such analyses are given in a previous

paragraph. The change was accompanied by a partial oxidation of the

Iron and a very noticeable reduction in the percentage of magnesia, it

being less than one-half as high as it is in the hornblende schist, with a

correspondingly large increase in the amount of lime present. The alka-

lies almost disappeared during the alteration, while the percentages: of

the other constituents remained practically the same.

Dr. Julien,** in his study of this phase of alteration in the hornblende

schist, came to the conclusion that intense local compression and strain’

were necessary for its development and that it was not connected with the

process of change to pegmatite. This alteration does occur along minor

fracture zones in the hornblende schist, but where observed by the writer,

the injection of pegmatitic materials also accompanied those where alter-

ation to epidote has taken place. It seems more plausible, therefore, to

think that the circulation of the solutions which brought about the neces-

sary chemical changes involved in this alteration did accompany the peg-

matitic injections which occur in these fractured zones.

The actinolite, tremolite and tale schists occasionally found interstrati-

fied with the mica schist, especially on Manhattan Island, are very similar

in their mode of occurrence to the hornblende schist just described. ‘They

undoubtedly have a similar origin, in that they represent much metamor-

phosed intrusive sheets of basic igneous rocks. In composition, these in-

trusives were probably somewhat more basic even than those from which

the ‘hornblende schists have been derived, since in order to get a meta-

morphic rock made up largely of such minerals as actinolite, tremolite

and tale, it would be necessary to have an igneous rock high in magnesia

and lime and comparatively low in silica, alumina and the alkalies.

“Op. cit., p. 446.

FETTKE, MANHATTAN SCHIST OF NEW YORK 227

- The igneous origin of the Harrison granodiorite gneiss has never been

questioned by those who have made a study of this rock. Its chemical

- composition is clearly that of a medium basic igneous rock, as a compari-

.son with analyses of massive igneous rock of similar composition will

show. Its uniformity of texture, structure and mineral composition over

large areas is another point in favor of such an origin. It probably en-

tered the older strata in the form of a large irregular laccolith and when

they were shales. There was thus a period of igneous activity antedating

the folding and dynamic metamorphism of the sediments. We reach this

conclusion because of the very marked foliated structure, clearly of sec-

ondary origin, which has been developed in the granodiorite. The strike

of the foliation is parallel to that of the mica schist which surrounds the

intrusive. | |

MASSIVE BASIC IGNEOUS ROCKS

In addition to the highly metamorphosed foliated basic igneous rocks

which occur as intrusives in the Manhattan schist, there is another series

which shows only slight or no effects of dynamic metamorphism. The

series appears as normal, massive, igneous rocks of basic composition and

of granitoid texture intrusive in the schist and as massive serpentine

derived from such rocks.

Cortlandt Series

- The largest of these intrusive masses of basic igneous rocks occurs just:

south and east of Peekskill, covering an area of about twenty-eight square

miles in the township of Cortlandt, the most northwesterly in Westchester

County, from which the series has taken its name.

It consists of an igneous complex made up of a great number of differ-

ent varieties of intrusive igneous rocks mostly of a basic nature which

grade into one another, often by almost imperceptible transitions. G. S.

Rogers in a recent paper* has discussed the geology of this intrusive mass

in detail. He has shown that there is a centrally located norite area

flanked on both sides by pyroxenites. The western pyroxenite probably

continues beneath the Hudson River, since these rocks outcrop again at

Stony Point. Between this western area of pyroxenites and the norites,

lies a diorite area. To the extreme northeast, the basic rocks are adjoined

by an area of granite.- The order of intrusion seems to have been first

pyroxenite, followed closely by the norites, the diorite and finally granite.

It is among the basic members of the series that gradations from one into

another appear, producing a large number of intermediate types.

% “Geology of the Cortlandt series and its emery deposits.’”’ Ann. N. Y. Acad. Sci., Vol.

XXI, pp. 11-86. 1911.

228 ANNALS NEW. YORK. ACADEMY. OF SCLENCES

Only slight evidences of dynamic metamorphism are found in the rocks

of the Cortlandt series.*° The degree varies considerably among the differ-:

ent types, the granite showing the least, while in the diorite appreciable:

effects of strain are at times discernible, although they are rarely sufficient

to be perceptible in a hand specimen. These effects are most noticeable

in the vicinity of inclusions of mica schist, and it is to the borders of’

foreign inclusions that the effects of dynamic metamorphism are usually

confined, Evidently, therefore, these rocks entered after or at least

toward the close of the period of intense folding, during which the shales

were converted into mica schists, because, if the intrusion had taken place

previous to that period, one should discover a foliated structure similar to

that present in the Harrison granodiorite.

Very marked contact metamorphism has frequently ous in the

mica schist in the vicinity of the intrusions. Mention has already been

made of this in describing the mica schist in the vicinity of Peekskill and

Crugers. G. H. Williams*’ has given an excellent description of a contact

zone from the vicinity of Crugers. The mica schist shows a constantly

increasing metamorphism as the intrusive rocks are approached. Garnet

becomes very abundant, and other contact metamorphic minerals such as

sillimanite, cvanite and staurolite make their appearance.

The inclusions of schist in the igneous rocks themselves naturally also

show the effects of contact metamorphism. G. S. Rogers** has come to

the conclusion that the emery deposits which appear at several localities

in the Cortlandt series are due to the more or less complete absorption of

such inclusions by the intrusive magma before it solidified.

Croton Falls Hornblendite

A similar but smaller area of basic intrusives having very much less’

variation in composition occurs in the vicinity of Croton Falls. This:

mass is about two and a half miles long and one-half mile wide starting

in at a point a little south of Croton Falls and extending in the form

of a ridge in a northeasterly direction on the east side of the Croton

River.

The rock at the northeastern end of this area is a massive dark green

coarsely crystalline hornblendite. Some biotite is also visible in the

hand specimen along with the hornblende. In thin section, under the

microscope, it shows a coarse granitoid texture. In mineral composition,

38G. S. Rocers: Op. cit., pp. 54-55.

37 Am. Jour. Sci., 3rd ser., Vol. XXXVI, pp. 254-269. 1888.

38 Op. cit., p. 81.

‘FETTKE, MANHATTAN SCHIST OF NEW YORK 229

it consists principally of a dark green hornblende and minor amounts of

‘dark brown biotite. 'Titanite, magnetite and a little pyrite appear as

accessory minerals. The hornblende shows marked pleochroism from

yellowish brown through greenish brown to deep green. The biotite also

exhibits intense pleochroism from light yellowish brown to deep brown.

‘This biotite hornblendite represents the typical composition of the in-

trusive mass at the northeast end of the area.

Along the eastern margin, the contact of the hornblendite with the

mica schist may be observed at several places. At one point several

apophyses of hornblendite were noticed extending into the schist. Some

of these retain the coarse crystalline texture of the main mass, while

others are somewhat finer grained. A thin section of this finer grained

type under the microscope shows medium granitoid texture and massive

structure. It consists almost entirely of hornblende with marked pleo-

chroism from lhght yellowish brown through greenish brown to dark

brownish green. It has well developed prismatic cleavage. A _ little

plagioclase and titanite are present as accessory constituents.

A short distance to the east of this occurrence, several sheets of horn-

blende schist similar to those already described occur interstratified with

the mica schist. This rock shows a distinct foliated structure. When

examined under the microscope, it is seen to consist largely of a deep

green hornblende, feldspar and a little quartz. ‘The accessory minerals

are magnetite, biotite and apatite. The hornblende shows marked pleo-

chroism from light yellowish brown through greenish brown to deep

green and has well developed prismatic cleavage. It does not show good

crystal boundaries but occurs in irregular grains interlocked with the

feldspar and quartz. These grains are usually oriented parallel to the

foliation. The feldspar is chiefly plagioclase giving extinction angles

up to 26° in sections at right angles to the albite lamelle and is evidently

an acid labradorite. Unstriated feldspar also is present. The feldspar

grains are irregular in shape and usually elongated parallel to the folia-

tion, but they do not show any crystallographic orientation. It is quite

evident that this rock has had a different history from that of the

apophyses of hornblendite occurring in the schist. The former was in-

truded prior to the period of folding, while the latter either at the close

or else after it had ceased entirely.

At the southwestern end of the area, the hornblendite in places grades

into a diorite. A section of the typical hornblendite as developed here

was made from a specimen taken from the east side of the railroad at

about one-quarter of a mile south of Croton Falls. It is a massive dark

green biotite hornblendite. . In thin section, it shows a coarse granitoid

230 ANNALS NEW YORK ACADEMY OF SCIENCES

texture. ‘The principal mineral present is a dark green hornblende as-

sociated with minor amounts of dark brown biotite. Small amounts of

feldspar, both striated and unstriated, and a very little quartz occur in

addition to the above, together with such accessory uuerals as magnetite,

apatite and titanite. Some of the hornblende is full of little quartz in-

clusions. Considerable evidence of strain is present in the section in the

form of undulatory extinctions and wedge-shaped twins in the feldspar.

On the west side of the track in the same cut, the rock has taken on

the composition of a diorite. The feldspar and hornblende appear in

about equal amounts. Most of the rock is massive, but some of it shows

a slightly foliated structure. In thin section, the texture is granitoid.

The principal minerals present are a feldspar, a deep green hornblende

and a dark brown biotite, together with minor amounts of magnetite,

apatite and titanite. The feldspar is mostly plagioclase, giving extinc-

tion angles up to 22° 30’ in sections at right angles to the albite lamelle,

which would indicate andesine. Some orthoclase also is present, as much

of the feldspar is unstriated and optically negative.

A number of inclusions of a schistose rock occur in the diorite at this

place. Their contacts with the latter are usually quite sharp. A thin

section of one of these, which forms a tabular, nearly vertical mass about

four feet wide, shows a marked foliated structure and medium-grained

crystalline texture. The principal minerals present are biotite, horn-

blende, feldspar and a little colorless pyroxene. Magnetite, apatite and

titanite are accessory constituents. The hornblende is a deep green va-

riety showing marked pleochroism from yellowish brown through brown-

ish-green to deep green. The biotite shows intense pleochroism from

light yellowish brown to deep brown. ‘The feldspar is mostly plagioclase,

giving extinction angles up to 20° 30’ in sections at right angles to the

albite lamellae, and is evidently an andesine. Another section from a

somewhat similar inclusion also shows a marked foliated structure. A

dark green hornblende is the principal mineral, associated with which

are deep brown biotite and minor amounts of apatite, titanite and pyrite.

In the railroad cut at Croton Falls itself, a dark nearly black foliated

rock is exposed. It has a medium coarsely crystalline texture. The thin

section reveals a deep green hornblende with well developed prismatic

cleavage, deep brown biotite and plagioclase. The accessory minerals are

magnetite and titanite. Farther north in the same outcrop, the structure

becomes even more foliated. A thin section from a specimen taken near

the northern end of the cut shows a marked schistose structure. The

minerals making up the rock are deep green hornblende with well de-

veloped prismatic cleavage, deep brown biotite, pale green augite and

FETTKE, MANHATTAN SCHIST OF NEW YORK 231

feldspar. ‘The feldspar is mostly plagioclase, an andesine, with extinction

angles up to 22° in sections at right angles to the albite lamelle. It is

optically positive. Feldspar is occasionally contained in the augite as

inclusions. Titanite, apatite and magnetite occur as accessory constitu-

ents.

This area of foliated diorite gneiss apparently represents an intrusion

of rather basic igneous rock which entered prior to or else during the

early stages of the period of folding which involved the whole region.

The hornblendite, on the other hand, was intruded during the latter

stages or else after folding had ceased entirely. There are, therefore,

two periods of igneous intrusion of rocks very similar in composition

represented. The inclusions of diorite gneiss in the diorite itself south

of Croton Falls are in accord with such a hypothesis. The hornblendite

intrusions at Croton Falls were probably contemporaneous with that of

the Cortlandt series at Peekskill. The hornblendite is in turn cut by a

number of large dikes of granitic composition, sometimes reaching a

thickness of two hundred feet or more. These range from true granite

to coarse pegmatites, a variation of texture which often appears in the

same dike within a very short distance. A discussion of these granitic

intrusives will be taken up later. Reference is made to them here to

show that the entrance of the hornblendite took place prior to the granite.

Diorite Dikes in the Vicinity of Bedford

Two occurrences of diorite in the form of dike-like intrusions have

been described by Professors Luquer and Ries from the vicinity of Bed-

ford in their paper on the geology of this region.*® One of these occurs

along the Bedford-Long Ridge Road about two and one-half miles south-

east of Bedford. The rock has a dark color, medium, coarsely crystalline

texture and massive structure. In thin section, one observes deep green

hornblende, showing good prismatic cleavage, pale green augite and feld-

spar. Most of the feldspar is unstriated but is optically positive and

therefore plagioclase. Titanite and apatite occur as accessory constitu-

ents. The augite apparently crystallized out before the hornblende, but

the two are very intimately intergrown. Both minerals are perfectly

fresh. Some of the feldspar has undergone slight alteration to an ag-

gregate of quartz, sericite and calcite.

A similar rock occurs about two and one-quarter miles south of Bed-

ford. It also has a dark green color, medium coarsely crystalline texture

and massive structure. A thin section reveals light green hornblende

” Am. Geol., Vol. XVIII, pp. 239-261. 1896.

232 ANNALS NEW YORK AOADEMY OF SCIENCES

with good prismatic cleavage, dark reddish brown biotite and feldspar.

The feldspar is mostly plagioclase, giving extinction angles up to 16° 30’

in sections at right angles to the albite lamellae. It is probably andesine.

A little microcline is also present. Much of the feldspar has been altered

to an aggregate of kaolin, sericite and quartz. Inclusions of biotite occur

both im the feldspar and amphibole, especially in the former. Apatite,

magnetite and a little titanite are present as accessory constituents. A

little pyrite forms an introduced mineral. In the edge of the mass, the

rock becomes very much finer grained. In thin section, however, one

still finds the granitoid texture. About equal amounts of light green

hornblende and dark brown mica are present. The other important con-

stituent is a plagioclase feldspar, evidently andesine, as it gives extinction

angles up to 20° 15’ in sections at right angles to the albite lamelle.

Some orthoclase also occurs, together with minor amounts of apatite,

titanite and magnetite.

Several other occurrences of diorite were observed in the area south

of Bedford. Sheets of hornblende schist are also quite numerous in this

vicinity, and the evidence again indicates that the intrusion of basic

igneous rocks took place at more than one period.

Serpentine

Serpentine is associated with the Manhattan schist at several places

in the area under discussion. These areas of serpentine are very similar

to the massive basic intrusive rocks just described, both in their mode of

occurrence and in their relations to the mica schist. D. H. Newland,*°

who has made a rather detailed study of them, has shown that they were

derived from basic intrusives, probably peridotites, which have undergone

serpentinization. \

The largest of these serpentine masses underlies the northern portion

of Staten Island. Smaller areas occur at Hoboken, New Rochelle and

Rye. Newland, in his study of the Staten Island serpentine, came

across unaltered remnants of olivine in some of his sections, showing that

the serpentine was derived from an olivine-bearing rock. ‘The writer has

also noticed similar remnants of olivine in several sections from this lo-

cality. A thin section of the dark green massive serpentine from near

the northern end of the area at Rye was also examined under the micro-

scope. It consists of antigorite, bastite, some calcite, iron oxides, a very

little tremolite and a few remnants of unaltered olivine, with a green

spinel or pleonaste and magnetite as minor accessories. ‘The bastite was

“ School of Mines Quart., Vol. XXII, pp. 307-317 and pp. 399-410. 1901.

FETTKE, MANHATTAN SCHIST OF NEW YORK 233

apparently derived from a pyroxene, while the antigorite represents

altered olivine, as it shows the typical mesh structure and occasionally

contains cores of unaltered olivine. Some of the serpentine from the

same locality has a slightly banded structure. A thin section of this

phase shows a distinctly foliated structure under the microscope and

consists largely of tremolite oriented parallel to the foliation, with anti-

gorite filling in the space between its prisms as well as the little crevices

and cracks throughout the section. The tremolite is perfectly fresh and

shows no alteration to serpentine. Some calcite is also present in the

section. The accessory minerals are fairly abundant pleonaste and

magnetite.

As has already been pointed out, these serpentine masses undoubtedly

represent altered basic intrusive rocks rich in olivine. From their mas-

sive structure, it would appear that they entered either toward the close

of the period of folding or after it had come to an end. They are, there-

fore, probably closely related to the Cortlandt series, the Croton Falls

hornblendite and the Bedford diorite which have already been discussed.

Views with regard to the alteration of peridotites and allied olivine

rocks to serpentine have changed considerably in recent years. It was

formerly thought that the alteration was brought about by the processes

of weathering, but now it is quite generally believed to be deep-seated.*?

Heated waters probably following closely upon the intrusion of the

magma itself and given off by it during solidification, it is thought, have

brought about the alteration of the olivine to serpentine while still buried

at considerable depths.

Hornblende Porphyrite

A dike of hornblende porphyrite crosses the granites and pegmatites

in a large cut just north of Springdale, about four and one-half miles out

of Stamford on the New Canaan branch of the New York, New Haven

and Hartford Railroad. As this is the only occurrence of a basic in-

trusive which is clearly of later age than the granitic intrusives in the

area studied, a brief description of it will not be out of place.

The dike is about three and one-half feet thick at its widest part but is

quite variable. ‘The strike of the dike is about N. 48° E., and the dip

is practically vertical. In a hand specimen, it shows a felsitic texture

and dark green color. When examined in thin section under the micro-

scope, the texture is apparently ophitic, but the space between the feld-

spar laths is occupied by hornblende instead of augite. The rock con-

41 ERNST WEINSCHENK : Allgemeine Gesteins-kunde als Grundlage der Geologie, pp.

119-121. 1902.

234 ANNALS NEW YORK ACADEMY OF SCIENCES

sists essentially of plagioclase feldspar and hornblende, with magnetite,

apatite and a very little biotite as accessory constituents. The plagio-

clase gives extinction angles up to 28° in sections at right angles to the

albite lamelle and is apparently an acid labradorite. The hornblende is

a green variety occasionally showing typical prismatic cleavage. It oc-

curs in small grains between the feldspar laths, and these are frequently

encroached upon by it so that the crystallographic boundaries of the

feldspar are not clean-cut. This would suggest that the space between

the latter might originally have been occupied by augite which had after-

wards altered to hornblende. No traces, however, of augite were noticed

in the section, and the hornblende in all other respects has the appearance

of being primary.

ACIDIC INTRUSIVES

In addition to the basic intrusives already discussed, there are other

types which are of granitic composition varying from true granites to

very coarse pegmatites and occurring as dikes, intrusive sheets and len-

ticular masses injected parallel to the foliation of the schist. The sheets

and lenticular masses are far more abundant than the dikes. They ap-

pear in one form or another in nearly every outcrop of mica schist.

Large masses of granite in bosses and batholiths outcrop, especially in

Connecticut just beyond the New York line, where they become quite

abundant. The Connecticut Geological Survey has given them the name

Thomaston* granite.

Thomaston Granite

As typically developed, the Thomaston is a light colored biotite granite

of medium to fine grain. It consists essentially of feldspar, quartz,

biotite and muscovite. At many places, it shows practically no gneissic

structure, but at other places is quite strongly foliated.

The granite covers a large area in the vicinity of New Canaan. It is

well exposed in a railroad cut about one-half mile south of New Canaan

on the New Canaan branch of the New York, New Haven and Hartford

Railroad. It is a light pink massive granite with medium-grained text-

ure. When examined in thin section under the microscope, it shows a

granitoid texture and consists of microcline and a little plagioclase. A

perthitic intergrowth of orthoclase and plagioclase may be occasionally

noticed. Apatite and zircun are present as accessory constituents. Some

of the feldspar has undergone slight alteration to kaolin and sericite,

while a little chlorite is developed on some of the biotite.

“Preliminary geological map of Connecticut. Conn. Geol. and Nat. Hist. Surv. Bull.

No. 7. 190%

FETTKE, MANHATTAN SCHIST OF NEW YORK 235

Farther south along the same railroad, just north of Springdale, an-

other large cut has been made in this same granite. The granite has a

coarse pegmatitic texture in places, although much of it remains normal,

medium-grained granitoid. The gradation from one into the other is a

gradual one. It contains several inclusions of a basic igneous rock.

These are usually massive and have a coarse crystalline texture and dark

green color. A thin section made from one of them shows a granitoid

texture and consists of green hornblende with good prismatic cleavage

and deep brown biotite. A little titanite is present as an accessory con-

stituent. The space formerly occupied by feldspar is now filled with an

aggregate of calcite, quartz and other secondary products.

The gneissoid phase of the Thomaston granite is well shown in the

vicinity of the Stamford reservoir, south of North Stamford. The lo-

cality is near the western border of the New Canaan mass and inclusions

of schist are a prominent feature. It is to these that the banded structure

of the gneiss is partially due.

Several smaller bosses of a similar granite occur to the west. One of

the largest is just west of Pelhamville in the vicinity of Mount Vernon.

The rock has a light gray color with a distinctly gneissoid structure and

medium-grained crystalline texture. Under the microscope in thin sec-

tion, it is granitoid and consists of microcline, quartz, orthoclase, some

biotite and muscovite and a little plagioclase. Apatite is the principal

accessory constituent.

Aplites and Pegmatites

Closely related genetically to the granites just described are a large

number of intrusive sheets and dikes varying in texture from medium

granitoid to very coarsely pegmatitic. Of these the intrusive sheets and

lenticular masses injected parallel to the foliation of the mica schist are

the most abundant. ‘They appear in nearly every outcrop of the schist.

Sometimes the injections are so numerous that the schist takes on a

gneissoid appearance and becomes an injected gneiss (Pl. X, Fig. 1).

They vary greatly in size from sheets 50 feet or more in thickness to those

less than an inch thick. ‘The same is true of the lenticular masses. The

intrusives which are parallel to the foliation of the mica schist are often

involved in all the intricate folds which have been developed in the latter.

The dikes of granite and pegmatite, on the other hand, cut across the

foliation. They also cut the intrusive sheets and lenses and likewise each

other, showing that they did not all enter at one time but that some are

later than others. They also vary greatly in size. In some cases, as at

Bedford Village, they reach a width of over two hundred feet, while in

other cases they only have a thickness of a fraction of an inch.

236 ANNALS NEW YORK ACADEMY OF SOIBNCES

In mineral composition, they vary from true granites and aplites in the

case of the medium-grained varieties to nearly pure quartz veins in the

case of the pegmatitic types. In the pegmatites, the greatest variation in

mineral composition is found. They range from coarse-grained granite

to pure quartz. In addition to the orthoclase, plagioclase (either albite or

oligoclase), quartz, muscovite, biotite and black tourmaline which are most

frequently present, a great many other more unusual minerals are some-

times available for the collector. Among these, the following have been

identified by various mineralogists: amphibole, apatite, antunite, beryl,

chrysoberyl, columbite, cyanite, cyrtolite, dumortierite, garnet, ilmenite,

iolite, monazite, pinite, titanite, uraconite, uraninite, uranotile, xenotime

and zircon.

In texture, these pegmatites are often very coarse. Feldspar crystals

may reach a length of several feet, as in the case of the Bedford dikes,

and many of the other accompanying minerals will have a correspondingly

large size.

Some interesting structural features are also developed in the pegma-

tites at times. Very coarse pegmatite may often be associated with me-

dium-grained granite in the same dike or sheet. The gradation from the

one into the other may be a gradual one or it may be quite abrupt. Where

such relations occur between granite and pegmatite, the former appears

to have been intruded first and to have been followed closely by the latter,

sometimes before the first had had an opportunity to completely solidify.

Often the granitic phases in the case of the intrusive sheets show an

original gneissoid structure.

A banded structure very similar to that sometimes seen in true veins is

also developed (Pl. IX, Fig. 2). In instances, this structure is due to the

growing inward from the walls of crystals of some of the minerals present,

very often the muscovite. At other times,.it is due to the progressive in-

crease in size of the crystals of the mineral constituents from the walls

inward. It may also be brought about when the intrusion of a granite or

aplite is closely followed by the injection of pegmatite along the same

fissure and before the former has had an opportunity to cool and com-

pletely solidify.

In the above description, it has been assumed that the pegmatites are

of igneous origin, a view now quite generally accepted by geologists.4? It

is thought that they represent the final products of crystallization of rock

magmas. ‘They are the “mother liquor’ so to speak, containing the bulk

4 W. C. BroGGrER: Syenit TVegmatitgiinge der siid norwegischen Augit und Nephelin-

syenite. Zeits. f; Kryst. u. Miner., Vol. 16, pp.'215/235. 1890.

JOSEPH P. Ippines: Igneous Rocks. Vol. I, pp. 273-276. 1909.

ALYRED HARKER: The Natural History of Igneous Rocks, pp. 293-299. 1909.

FETTKE, MANHATTAN SCHIST OF NEW YORK 237

of the water, boric, carbonic and hydrosulphuric acids, the fluorides,

chlorides and borates of the alkali metals and of the rare earths along

with some of the silicates, free silica and other oxides which remain be-

hind after the greater portion of the magma itself has solidified. This

“mother liquor” is later extruded through fissures developed in the cooling

mass and the pegmatites are, therefore, found as dikes in the igneous rock

from which they were derived and in the adjacent wall-rock.

The exceedingly coarse crystalline texture and accompanying struc-

tures of the pegmatites are due to the presence of the gases and mineral-

izers in the magma from which they crystallized. Just what per cent of

the entire amount of the residual magma they represent is hard to say.

Professor Iddings** states that the proportion of gas present probably does

not amount to more than ten times that present in the original magma

from which the pegmatitic “mother liquor” was differentiated. From

this it varies greatly down to cases where it is the same as the parent

magma. A medium-grained granite or aplite then results.

The pegmatites of southeastern New York State are undoubtedly re-

lated genetically to large batholithic masses of intrusive granite. It is

highly probable that the large areas of granite previously described which

have been so extensively uncovered by erosion in western Connecticut rep-

resent these intrusive masses. The area farther to the west is very likely

also underlain by other batholiths which have not yet been exposed except

in an occasional projecting knob. Where the granite appears at the sur-

face in western Connecticut, it often passes, as already mentioned, into

coarse pegmatite. The transitions can best be explained by imagining

the pegmatites to be injected into overlying but only partially cooled and

solidified portions of the original magma. The two would then be very

closely related. Also as these granite areas of western Connecticut are

approached, the pegmatitic sheets and dikes become very abundant and of

extensive size, indicating that there must be some common genetic relation

between them.

The granitic intrusions just described probably accompanied the great

orogenic movements which resulted in the intense folding of the rocks of

this region, including the Inwood limestone and Manhattan schist. Such

periods, as Professor C. R. Van Hise*® has pointed out, are very favorable

for the entrance of igneous rocks. The relations of the intrusive sheets

and injected lenses of pegmatite and granite to the mica schist are such

that they must in many cases have penetrated the older rocks before the

period of folding had come to an end. The sheets and lenses are often as

“ Op. cit., p. 276.

45 “‘HMarth Movements.” Trans. Wis. Acad. Sci. Arts and Letters, Vol. II. 1898.

238 ANNALS NEW YORK ACADEMY OF SCIENCES

intricately folded as is the schist itself. On the other hand, they do not

show much evidence of having come in prior to the folding since; had that

been the case, evidences of considerable crushing and recrystallization of

the coarse pegmatite would be expected. The crushing and recrystalliza-

tion, however, fail, as the texture of the sheets and lenses is practically

the same as that of the dikes which were intruded later and which are not

involved in the folds. It seems reasonable, therefore, to believe that the

first intrusions of granite and pegmatite accompanied the period of fold-

ing itself.

In the case of the Manhattan schist, the shales which were converted

into mica schist during this period of folding yielded most readily along

planes parallel to the bedding and naturally the early intrusions followed

these lines of weakness, giving rise to the intrusive sheets and injected

lenses which were drawn out and pinched off during the folding. In the

case of the Inwood limestone, conditions were somewhat different. This

was a more massive formation, and the bedding planes were not particular

lines of weakness. Very few intrusives entered parallel to them. The

magma rose through fissures and gave rise to true dikes where it solidi-

fied. These dikes are usually of fairly large size when they do occur, but

they are not as abundant as in the mica schist (Pl. IX, Fig. 1).

The intrusive activity continued during a long interval of time, extend-

ing even beyond the period of folding. The later intrusions took the

form of dikes which often cut one another, showing that some came in

earlier than others, thus emphasizing the fact that igneous manifestations

continued for a long time after the folding had ceased. The relations are

not surprising because the pegmatites represent the final differentiation

products of the great masses of granite.

In the case of igneous intrusions so richly supplied with water and other

mineralizers as the pegmatites must have been, rather marked contact

metamorphic effects would naturally be expected, especially in the case of

the limestones. In their field occurrence, however, this does not appear

to be the case. The dikes of pegmatite ten feet or more thick, apparently

have produced no contact metamorphic effects on the limestone whatever.

The explanation for this may be the one which Dr. E. Weinschenk*® has

given, namely, that when the pressure at the time of the intrusion is suffi-

ciently great the CO, of the calcite and dolomite does not have an oppor-

tunity to escape, and hence the silica cannot combine with the lime and

magnesia to form silicates. Occasionally the schist in immediate contact

with the pegmatite becomes very rich in garnet. These contact phases of

46 Grundziige der Gesteinskunde, I Teil, p. 105. 1902.

FETTKE, MANHATTAN SCHIST OF NEW YORK 939

the schist usually have also a very high content. of feldspar;.a portion of

which was undoubtedly derived from the pegmatite, Cyanite occasionally

appears, in long bladed crystals having a slight bluish tinge, in portions

of the schist which have been thoroughly saturated with pegmatitic ma-

terial. In this case, it is apparently of contact metamorphic origin.

Undoubtedly the pegmatites derived a portion of their constituents from

the rocks through which they were intruded. Such minerals as garnet

and biotite probably owe their origin to this source. Black tourmaline

similar in every respect to that found in the pegmatite itself often occurs

in the mica schist in the vicinity of the pegmatitic intrusions and has

evdently resulted from the emanations from this source.

That these granitic and pegmatitic intrusions played a very important

role in the metamorphism and recrystallization of the original shale of the

Manhattan formation into mica schist, there can be but little doubt.

Most of the water associated with the intrusions must have been given off

when solidification occurred, since it does not enter into the composition

of any of the resulting minerals to any extent. This water must have

been very effective in bringing about recrystallization. The local tem-

perature must also have been raised by these intrusions. Edson 8. Bas-

tin*’ in his study of the Maine pegmatites has come to the conclusion that

they crystallize at a temperature in the neighborhood of 575°C. The

New York pegmatites are very similar to the Maine-occurrences. . These

intrusions must, therefore, be regarded as very effective agents in the

metamorphism of the original shale into mica schist. Other influences

were the deep burial beneath overlying sediments and the severe folding

and crumpling which followed the deposition of the original sediments.

Bedford “Augen” Gneiss

In discussing the mica schist in the vicinity of Bedford Village, men-

tion has already been made of the “‘augen” gneiss which is so frequently

associated with it. The region in which the structure occurs covers an

ovoid area southeast of Bedford Village. The long axis extends in a

northeast-southwest direction and has a length of about six miles. The

width does not exceed two and one-half miles.

The “augen” structure is developed in two types of rock, a mica schist

and a hornblende schist, but the entire area does not have the “augen”

structure. It appears in bands usually parallel to the foliation. The

bands grade into the ordinary schist by the gradual disappearance of the

“augen” (PI. X, Fig. 2). Sometimes the “augen” stop rather suddenly,

47U. S. Geol. Surv. Bull. No. 445, p. 45. 1911.

24() ANNALS NEW YORK ACADEMY OF SCIENCES

while at other times they drop out very gradually, so that the gradation’

from schist into “augen” gneiss is an almost imperceptible one. The

width of these belts varies from those less than a foot to those several

hundred feet wide.

About two-thirds of a mile southeast of Bedford Village along the road

to Stamford, the “augen” gneiss is associated with a mica schist. In thin

section under the microscope, the schist shows a moderately fine crystal-

line texture and a distinctly fohated structure. It consists chiefly of

quartz, biotite and feldspar. The biotite is a deep reddish brown and is

oriented parallel to the foliation. The feldspar is mostly plagioclase

which gives extinction angles up to 30° in sections at right angles to the

albite lamelle. It is optically positive and is evidently an acid labra-

dorite. Some microline is also present. The quartz and feldspar occur:

in irregular interlocking grains sometimes elongated parallel to the —

tion. Pyrite and a little apatite are also present. ;

The “augen” of the gneiss consist of a pink feldspar twinned on the

Carlsbad law and reaching a length of over an inch. They are very often:

rectangular in outline, although the ends are usually rounded. At other

times, they take on an elliptical shape. The long axes are usually ori-

ented parallel to the foliation, although not always so. “Augen” of white

feldspar showing albite twinning are also present, but they do not reach

as large a size as the pink ones. These give extinction angles up to 13°

in sections at right angles to the albite lamelle and are probably albite.

Beside the feldspar, fairly large grains of quartz sometimes appear in’

veinlets with finer feldspar. In thin section, the pink feldspar is seen to’

be mostly microline. At times it exhibits a perthitic intergrowth with

plagioclase. Quartz is seen in little veinlets throughout the rock. It

sometimes contains inclusions of rutile. The finer matrix of the “augen”

gneiss is very similar to the mica schist already described. It consists ,of

quartz, a deep brown biotite, feldspar, mostly microline, and a little mag-

netite. The structure is distinctly foliated. The ‘‘augen” gradually dis-

appear at the outer margins of the belt of “augen” gneiss which grades

into the schist. Where typically developed the “augen” constitute a large.

percentage of the entire mass of the rock. |

Another specimen of the “augen” gneiss taken from a belt along a

road about one mile south of Bedford shows only a pink feldspar which

is nearly always twinned according to the Carlsbad law. The feldspar

is not as abundant as in the occurrence described above but is similar in

size, shape and orientation (Pl, XI, Fig. 1). Small veinlets of peg-

matitic material parallel to the foliation are present. “Augen” of feld-

FETTKE, MANHATTAN SCHIST OF NEW YORK 241

spar are occasionally associated with these. In thin section, the matrix

in which the feldspar ‘“‘augen” are imbedded has a medium-grained crys-

talline texture and distinctly foliated structure. Its minerals are quartz,

biotite, some feldspar, mostly microcline, and a little plagioclase. Apa-

tite occurs as an accessory constituent. Many little veinlets of intro-

duced quartz parallel to the foliation are present with which the feldspar

“augen” are sometimes associated. These feldspar “augen” consist of

orthoclase and microcline and sometimes show a perthitic intergrowth

with plagioclase.

About two miles south of Bedford along an east and west road, there

is an interesting outcrop which exhibits a transition from a true pegma-

titic sheet parallel to the foliation, into “augen” gneiss and finally into

mica schist with only a few “augen” of feldspar. Plate XI, Fig. 2, shows

a specimen in which prominent “augen” of pink feldspar are developed

along little pegmatitic stringers with which the schist is thoroughly in-

jected.

About one and one-half miles northeast of North Castle, the “augen”

structure is developed in a hornblende schist. This is a black more or

less fohated rock. In thin section, one observes plagioclase, dark green

hornblende with good prismatic cleavage and deep brown biotite. The

plagioclase gives extinction angles up to 12° in sections at right angles

to the albite lamellz and is therefore oligoclase-andesine. Apatite is an

abundant accessory constituent. Magnetite and a little titanite are also

present. ‘l’he “augen” show very much the same characteristics as those

already described. They consist of orthoclase and some microcline. In

one case, a micrographic intergrowth of orthoclase and quartz was no-

ticed. The bands of “augen” gneiss here have very much the same

relation to the hornblende schist as the others did to the mica schist. In

this case, the matrix in which the “augen” occur consists essentially of

the same constituents as the hornblende schist.

Professors Luquer and Ries,** in their study of this “augen” gneiss,

came to the conclusion that it represents a metamorphosed igneous rock

of the composition of a granite or aplite. The metamorphic action, they

thought, produced the gneissoid structure by pressure and a granulation

of the minerals, the unsheared portions of the rock remaining as “augen.”

A chemical analysis made by the writer of the “augen” gneiss described

from the outcrop along the road two-thirds of a mile southeast of Bed-

ford Village along the road to Stamford gave the following composition :

Op. Cit., p. 200.

242 ANNALS NEW YORK ACADEMY OF SCIENCES

Analysis of Augen Gneiss Norm

Per cent Per. cent

SIO ie oe orale eee: eeene Deets ee OF202 Quast eect cee hie ae eee 19.08

UA K @ PRU eo Mee rope Mea Nap MAS | 13:96. “Orthodlase .yo ee vere oe een 31.69

(CES OAR ogee tae ere ia Oh i eA ea ed BO, CANDIES Ae «oes tere bles ermereiages es 30.39

ECO Se er eye eee ree 2.3 ~ Anoreiiters. .. \. oe eee 6.12

101 25 OP ee Saree a ee PS Soa L2r. SDiopsidets sas4 Ae tee eee 5.74

CaO) 2. Asner an ety eeveheet ok 2/69. My peérsthene cab sane 2 roe 1.26

NBO ae ents cde ae eerretine 3.61. Marnetite 22.0... hance oe picts 3.48

1G Hiei a gE Re SOR er at ee gay Oo boat) Timenite see. ba siooeeereeee ees 2.62

EEO) Shes Soe ait, Game ie eae 36

PE Ort OR oh peers 502 Totals. zoe eee eee 100.38

MOR orc Se Saat ape ier noe 1.41

TROBRIL Ss Lac, oa chee Ree ee 100. 70

Magmatie symbol II. 4.23. Adamellose.

The analysis would rather seem to uphold the above conclusions as it

corresponds to that of an igneous rock of about the composition of a

quartz monzonite.

There are other features, however, which cannot very well be explained

by such a hypothesis. The occurrence of the “augen” gneiss in bands of

varying width and their gradation into mica schist or hornblende schist

cannot very well be explained by such a supposition. The fact that where

the “augen” gneiss is associated with mica schist, its matrix has the com-

position of the mica schist and where, with hornblende schist, that of the

hornblende schist, does not favor such a conclusion. If the “augen”

gneiss represents a metamorphosed igneous rock in which the feldspar

“augen” represent original unsheared feldspar crystals, the original rock

must have had a very coarse granitoid texture or else a porphyritic texture

in which the phenocrysts were feldspar.. In either case, it is hard to see

why these “augen” of feldspar should have their present distribution in

local belts through the rest of the rock. It is also hard to account for

such a variation in matrix as is represented in different places.

The apparent gradation of a pegmatite sheet into “augen” gneiss by

a thorough injection of the adjoining schist with pegmatitic material,

and the final gradation of this into true schist with only a few “augen”

of feldspar, suggests that the “augen” gneiss represents sheared zones of

schist which have been thoroughly injected and permeated with pegma-

titic material consisting largely of potash feldspar together with some

plagioclase and quartz. The only peculiar feature, assuming that this

is the correct explanation, is that the feldspar took on a more or less

crystalline outline. That this injection belonged to the earlier stages

FETTKE, MANHATTAN SCHIST OF NEW YORK 943

of the pegmatitic intrusions is shown by its relationship to the other

schist and the later pegmatitic intrusions.

The frequent association of these feldspar “augen” with little veinlets

of secondary quartz and pegmatite favors such a hypothesis. The fact

that micrographic and perthitic intergrowth are occasionally present in

the orthoclase and microcline also points toward such an origin as such

intergrowth would hardly be expected in feldspar representing pheno-

erysts of a sheared porphyry. The variation in the mineral composition

of the matrix can also be explained on this basis, as it would be that of

the sheared rock into which the injection took place.

Occurrence of Zeolites in the Manhattan Schist

Zeolites are occasionally found lining cavities and small crevices in the

Manhattan schist. Among them, thomsonite, natrolite, analcite, chaba-

zite, phacolite, harmatome, heulandite and stilbite have been reported

from Manhattan Island.*°

Specimens of stilbite and chabazite occurring in the Manhattan schist

in this manner were given to the writer by Mr. J. R. Healy, assistant

engineer with the New York Board of Water Supply. They were ob-

tained from Shaft 15 of the Catskill aqueduct at 65th Street and Cen-

tral Park West. The crystals of stilbite and chabazite lined the walls

of a small open crevice which followed the plane of schistosity of the

mica schist for a short distance. ‘The stilbite has a-honey-yellow color

and has crystallized in sheaf-like and radiated masses. The chabazite is

white in color and has a nearly cubic form. It precedes the stilbite in

order of crystallization, as the latter sometimes grows on top of it. Little

veinlets of pegmatitic material and epidote occur in the schist closely

associated with the stilbite and chabazite.

When examined in thin section under the microscope, it is seen that

much of the biotite of the mica schist has been altered to chlorite. The

orthoclase of the little pegmatite stringers is also much kaolinized. As-

sociated with these pegmatitic stringers but later in origin are veinlets

of quartz, which, under the microscope, appear as a fine mosaic of little

grains. Veinlets of epidote with a little accompanying calcite are often

associated with these quartz stringers and cut them in such a way as to

show that they were the last to be introduced.

The formation of the zeolites probably accompanied the last Bis!

of the pegmatitic intrusions. The zeolites were probably deposited by

4B. B. CHAMBERLIN: ‘“‘The Minerals of New York County.” Trans. N. Y. Acad. Sci.,

Vol. VII, No. 7. 1888.

244 ANNALS NEW YORK ACADEMY OF SCIENCES

the accompanying heated waters in little crevices which had been de-

veloped after the period of folding had come to an end. In the modern

view,°° zeolites are believed to have been deposited by heated waters ac-

companying the last stages of igneous activity. The mere leaching of

the necessary constituents by surface waters in the belt of weathering is

not considered sufficient. Professor Brogger** has also described zeolites

from pegmatite dikes where they occur as products of the last stages of

crystallization.

SUMMARY

The Manhattan schist is a series of much metamorphosed argillaceous

and sandy shales, argillaceous sandstones and arkoses which represent a

thickness of several thousand feet. The argillaceous sediments were laid

down conformably upon the underlying limestone, the limestone grading

into calcareous shales at the contact. After their deposition, they were

penetrated by a series of basic igneous rocks, largely in the form of sheets

and sills. Then a period of great orogenic movements set in which

brought about intense folding in the whole area. The original sediments

had been buried to a sufficient depth to come into the comparatively

shallow zone of anamorphism for shales. <A large series of granitic in-

trusions accompanied the folding. The granites are huge batholiths

which have only been exposed by later erosion at the surface in a few

places in this area. Radiating from the batholiths are numerous granitic

and pegmatitic dikes. During the earlier stages, the intrusions occurred

mainly along the bedding planes which were the lines of weakness, and

in many places the rock was so thoroughly injected in this manner that

it has become an injected gneiss.

The burial to a considerable depth and the intense stress set up by the

orogenic movements which produced the folding, together with the meta-

morphic effects of the granitic and pegmatitic intrusions, brought about

the recrystallization of the constituents of the original shale and asso-

ciated sediments into mica and related schists. The earlier basic in-

trusives were also involved in the dynamic metamorphism. The metamor-

phism appears to be least pronounced north of Croton Village and in

those places in the vicinity of Peekskill where the schist did not come

under the influence of the local contact metamorphic effects of the Cort-

landt series.

50 WALDEMAR LINDGREN: “Some modes of deposition of copper ores in basic rocks.”

Econ. Geol., Vol. VI, pp. 687-694. 1911.

51 Zeits. f. Kryst. u. Miner., 16 Band, pp. 168-173. 1890.

FETTKE, MANHATTAN SCHIST OF NEW YORK 245

The granitic and pegmatitic intrusions, especially the latter, continued

for some time after the folding had ceased. ‘These later intrusions took

the form of dikes. ‘Toward the end of the period of folding, or perhaps

after it had ceased altogether, a number of intrusions of basic igneous

rocks occurred at several places in the area under discussion. ‘The

largest of these constitutes the Cortlandt series Near Peekskill. Some of

the igneous rocks were rich in olivine and have been altered to serpen-

tine. Granitic and pegmatitic intrusions were still occurring at the time,

as these later basic rocks are cut by granite and pegmatite dikes in sev-

eral places. A hornblende porphyrite cutting pegmatite near New

Canaan, Connecticut, is the latest in age of the intrusives present in the

region under discussion.

The age of the Manhattan schist, as already mentioned, is still a dis-

puted question. This will be further discussed after the formations north

of the Highlands have been described.

PEEKSKILL PHYLLITE

As has already been mentioned in a previous chapter, the section across

the Peekskill Creek valley northeast of Peekskill contains a series of for-

mations which are quite different from those exposed anywhere else south

of the Highlands, with the exception of Tompkins Cove on the west side

of the Hudson River, which is merely a continuation of this same belt.

The lowest member here resting upon the gneiss is a quartzite about six

hundred feet thick. This is followed by a fine-grained crystalline lime-

stone varying in color from blue to white which in turn is succeeded by a

dark gray to black phyllite. On account of folding, it is hard to deter-

mine the exact thickness of the limestone and phyllite, but the former is

probably about one thousand feet, while the thickness of the latter is

probably a great deal more. The phyllite is well exposed on the north-

west side of the valley which occupies the limestone belt, while the quartz-

ite shows on the southeast side. All the formations dip steeply toward the

southeast. Most of the phyllite has a dark bluish gray color and rather

fine texture. Pyrite crystals are quite abundant in certain beds.

A thin section of the fine dark bluish gray rock, when examined under

the microscope, shows a distinctly foliated structure and is found to con-

sist largely of an aggregate of minute quartz grains and sericite flakes,

with abundant iron oxides scattered through the whole mass and also to a

certain extent concentrated in distinct bands parallel to the foliation.

Occasionally, small stringers of secondary quartz also parallel to the folia-

tion may be noticed.

246 ANNALS NEW YORK ACADEMY OF SCIENCES

_A chemical analysis made by the writer of the above described speci-

mens gave the following composition :

Analysis of Phyllite

Per cent

Si@;) Peeks te atnsiece ee eee 61.04

ATO’) ita Che ah eee ihe oe eee 15..87

WOO ki sew sels wee oe eee 1.74

We ek ocak eee ee eee 4.32

NGO Se Sere eee cae 3.26

Caio aecek ae eee On teed te 2.39

Na Oh 2 eee es ee cee 1.83

KEQOv his oh el cee se ae 3.26

IC) Se vs ced reine ee ee eee ee 1.82

POSS. eg eee te see .09

COG. ins seta. eames Sereno 4.24

WiQs OS sete Cen ee eee aol

tS sleds epee ee 100.77

A lighter colored coarser-grained type was also examined under the

microscope. It consists largely of quartz and sericite, with minor amounts

of black iron oxides. A little calcite in isolated crystals is also present.

Recrystallization has proceeded much further than in the previous case.

The sericite flakes are all oriented parallel to the foliation, while the

quartz grains are all more or less elongated parallel to it (Pl. XIV,

Fig. 1). An occasional quartz grain reaches a diameter of .5 millimeter,

but most of them are much smaller.

All who have studied this section have correlated these formations with

the Poughquag-Wappinger-Hudson River series north of the Highlands.

Dr. Charles P. Berkey,®* who has made the most recent and detailed study

of this area, has come to the conclusion that these are not, however, the

equivalent of the Inwood-Manhattan series south of the Highlands, as

others have thought, basing his view upon the relation of the Peekskill

Valley formation to a belt of limestone occupying Sprout Brook Valley to

the northwest, which he thinks is the equivalent of the Inwood limestone.

A further discussion of these two views will be taken up after the forma-

tions north of the Highlands have been described.

POUGHQUAG-WAPPINGER-HUDSON RIVER SERIES

Just north of the Highlands of the Hudson and east of the Hudson

River itself, a quartzite to which the name Poughquag has been given

sa“Structural and Stratigraphic Features of the Basal Gneisses of the Highlands.”

N. Y. State Mus. Bull. 107, pp. 361-378. 1907.

FETTKE, MANHATTAN SCHIST OF NEW YORK 247:

rests unconformably upon the pre-Cambrian gneisses. ‘This is followed

conformably by a limestone known as the Wappinger, which in turn is

succeeded by a thick series of shales belonging to the Hudson River group.

POUGHQUAG QUARTZITE

The Poughquag quartzite reaches a maximum thickness of about six

hundred feet. It is usually a compact, granular silicified quartz sand-

stone of medium grain, with occasionally a fine conglomerate at the base

and sometimes finer grained quartzitic shales at the top. Its fossil con-

tents show that it is of Lower Cambrian age.**

In certain places, as along the Matteawan inliers of pre-Cambrian gneiss,

a coarse granitic stratum rests on the upturned gneiss, and this is fol-

lowed by a somewhat foliated, finer grained quartzitic rock. This granitic

stratum has been interpreted by C. E. Gordon‘ as representing decayed

portions of the old pre-Cambrian gneisses which were partly reworked

by the advancing Cambrian sea and later covered by quartzitic sands.

Usually, wherever the relationship of the quartzite to the gneiss can be

made out, the contact is seen to be an unconformity, and it is evident that

the foliated structure of the gneisses dates back to a period of folding

prior to the deposition of these Lower Cambrian sediments.

Since the deposition of the quartzite, the region has been involved

in extensive thrust faulting which has shoved the older pre-Cambrian

gneisses upon the later formations. In some cases, the quartzite moved

with the gneiss, while in others the gneiss moved over it. The quartzite,

although never violently folded, was nevertheless greatly disturbed by

orogenic movements in certain places.

WAPPINGER LIMESTONE

Following the Poughquag quartzite just north of the Highlands comes

the Wappinger limestone. In this region, it has a thickness of about one

thousand feet. Portions of it are magnesian in character. A belt of this

limestone runs from the Hudson River in a northeasterly direction along

the northwestern margin of the Highlands and then turns northerly up

the Clove Valley where it dies out. To the east of the Clove Valley, it

passes underneath a thick series of phyllites and schists, appearing again

farther east in the Dover-Pawling Valley.

C. E. Gordon®* has identified fossils of Lower Cambrian, Beekmantown

“63 J. D. DANA: Am. Jour. Sci., 3rd ser., Vol. 3, pp. 250-256. 1872.

% “Geology of the Poughkeepsie Quadrangle.” N.Y. State Mus. Bull. 148, p. 46, 1911,

So Tpid:, pi T1.

248 ANNALS NEW YORK ACADEMY OF SCIENCES

and Trenton ages from this belt, showing that all these terranes are pres-

ent. He called attention to the fact that as one goes eastward in this belt

the rock displays greater crystallinity. Much evidence of crushing be-

comes manifest and bunches and veinlets of calcite, nests of quartz and

stringers are abundant, indicating hydrothermal activity. These changes

have obliterated all traces of organic remains.

The limestone of the Clove Valley is essentially a fine-grained gray to

white crystalline variety. ‘The individual calcite grains range in size

from one-tenth to two-tenths millimeter in diameter. Small bunches

and stringers of secondary quartz are frequently present. On the east and

west, the limestone is overlain by phyllites belonging to the Hudson River

series.

The limestone appears again six miles to the east in the Dover-Pawling

Valley. Here it is considerably more metamorphosed, as is shown by its

coarse crystalline texture. In places, as in the vicinity of South Dover

and Wingdale, it is quite pure and makes an excellent marble. It has

been quite extensively quarried at these places. At other localities,

phlogopite and tremolite occur quite abundantly distributed through it.

The development of tremolite crystals in the limestone is especially well

shown in some of the cuts along the New England Railroad from Towners

to West Patterson. They frequently become an inch long and over a

quarter of an inch in diameter and make up a goodly percentage of the

rock.

HUDSON RIVER SLATES, PHYLLITES AND SCHISTS

Resting on the Wappinger Limestone is a thick series of slates belong-

ing to the Hudson River group. The slates range in age from Trenton

into Cincinnatian.** These strata are strongly folded and crumpled, and

for this reason their exact thickness is unknown, but probably exceeds

several thousand feet.

Just east of the Hudson River, a slaty shale derived from an impure

argillaceous mud is the predominating type. Interbedded with this shale

are occasional sandstone beds. Following these slates eastward from the

Hudson River, an increase in the amount of metamorphism which they

have undergone becomes very noticeable, In the vicinity of Arthursburg,

they have been altered to slaty phyllites and graywackes.

The formation at Arthursburg is typically a slaty phyllite broken up

into a large number of comparatively thin lamella by numerous parallel

cleavage planes. It has a dark bluish gray color and is fine grained. In

thin section under the microscope, it is seen to be made up chiefly of a

56C, EH. Gorpon: N. Y. State Mus. Bull. 148, p. 96. 1911.

FETTKE, MANHATTAN SCHIST OF NEW YORK 249

fine aggregate of quartz and sericite. The quartz occurs in minute grains

usually more or less elongated parallel to the cleavage. The little sericite

scales occur interspersed among the quartz with their basal section in the

plane of cleavage. Considerable amounts of iron oxide occur scattered

throughout the mass. A little biotite in minute scales has also com-

menced to develop. Bands with sericite predominating over the quartz

alternate with bands in which the quartz predominate.

Going eastward, the rock begins to take on more and more the nature

of a true phyllite. A thin section from a specimen obtained three miles

east of Arthursburg has the grains of quartz and flakes of muscovite some-

what coarser than that at Arthursburg. Considerable chlorite also ap-

pears in this particular specimen. Oxides of iron are plentiful, often con-

centrated along more or less parallel bands. Magnetite occurs in grains

up to five-tenths millimeter in diameter. In crystallizing, it has forced

the other mineral aside, and the flakes of sericite now curve around it.

The structure is distinctly foliated.

Four miles east of Arthursburg is a Welt of Wappinger limestone, the

more ready erosion of which accounts for the Clove Valley. On the east

side of the valley, the phyllites are again found overlying the limestone.

The rock has a rather fine texture, with numerous easily recognizable

flakes of biotite scattered through it. Pyrite also is abundant. Under

the microscope, the fine-grained mass is seen to consist of an aggregate of

sericite and quartz, associated with which are large quantities of iron

oxide in very fine particles. In the finer matrix occur numerous larger

and more prominent flakes of biotite with their basal sections in the plane

of foliation (Pl. XIV, Fig. 2). They all show a more or less ragged out-

line. Pyrite is present in considerable quantities. The fine-grained ma-

trix in this case is a good deal more coarsely crystalline than that found

west of the Clove Valley.

A short distance east of the above contact, the biotite becomes a very

prominent feature. Occasional crystals of garnet also appear. Under the

microscope, it is seen that the fine-grained mass of sericite, chlorite and

quartz with some iron oxide is a little coarser than in the previous cases.

This shows a distinct foliated structure. On the other hand, the biotite is

not oriented parallel to the foliation but occurs in rather prominent flakes

at all angles to it. A few isolated grains of garnet appear for the first

time.

About one-half mile east of the above locality, the phyllite begins to

grade into a fine-grained schist. The sericite or muscovite becomes quite

abundant and gives the rock a satiny luster. Garnet becomes very

prominent. Its crystals average about one-tenth inch in diameter and

250 ANNALS NEW YORK ACADEMY OF SCIENCES

show good crystal outline. In thin section under the microscope, the

rock shows a distinctly foliated structure and is seen to be made up of an

aggregate of sericite and quartz. In it are large crystals of garnet, biotite

and staurolite. The latter mineral makes its first appearance but is not

as yet very abundant.

A specimen collected two and one-half miles east of the above locality

shows abundant biotite and an occasional garnet crystal embedded in a

fine-grained matrix. This matrix resolves itself under the microscope

into an aggregate of quartz and sericite, with abundant iron oxide scat-

tered through it. A little plagioclase and a few small tourmalines are

also present. The rock shows a distinctly foliated structure (Pl. XIV,

Fig. 3). It is evident that the metamorphic changes here have not

reached quite so advanced a state as in the case above. Most but not all

of the biotite crystals are oriented parallel to the foliation.

A specimen from an outcrop occurring three and one-half miles east of

the Clove Valley showed a medium fine texture and distinctly foliated

structure. Abundant garnet and biotite show in the hand specimen.

Under the microscope, the main mass of the rock is seen to consist largely

of quartz and sericite. The biotite is full of quartz inclusions.

A specimen collected a short distance east of the above locality shows a

marked schistose structure. It has a silky luster due to the presence of

numerous fine sericite flakes. Garnet and biotite are prominently devel-

oped. In thin section, the sericite flakes all show more or less parallel

alignment to the foliation. Quartz occurs in small grains interspersed

between the sericite. Biotite is present in considerable amounts in fairly

large flakes embedded in this matrix. The same is true of garnet. An

occasional staurolite crystal has also been developed. Some chlorite is

present. The texture in this specimen is a good deal coarser than any

described thus far.

A half mile east of this locality near the western contact of the Dover-

Pawling limestone with the schists the rock is quite coarsely crystalline.

Garnet, biotite and abundant staurolite crystals can be readily made out

embedded in a fine matrix which has a silky luster due to the abundant

presence of muscovite. The rock is a typical staurolite-mica schist. In

thin section, the matrix is seen to be made up of medium-grained aggre-

gate of muscovite and quartz, with an occasional grain of orthoclase and

plagioclase (Pl. XIV, Fig. 4). The quartz occurs in fairly large grains

at times. The flakes of muscovite are oriented parallel to the foliation.

Biotite is also abundant and occurs in larger flakes than the muscovite

also oriented parallel to the foliation. Staurolite and garnet with good

crystalline outlines occur abundantly interspersed in this matrix. They

FETTKE, MANHATTAN SCHIST OF. NEW YORK 251

are full of quartz inclusions. A little chlorite derived from altered biotite

is also present.

After crossing the Dover-Pawling Valley, the schists are again exposed

overlying the limestone on the east side of the valley. A specimen col-

lected from the west slope of Purgatory Hill east of Pawling, when ex-

amined under the microscope, shows a medium coarse texture and dis-

tinetly foliated structure, due chiefly to the parallel orientation of the

biotite (Pl. XIV, Fig. 5). The mineral composition is principally bio-

tite, plagioclase, orthoclase and quartz. The plagioclase is present in

large amount. It has a maximum extinction angle of 25°, measured in

sections at right angles to the albite lamellae, which would indicate an

andesine or acid labradorite variety. A few small garnet grains and some

magnetite are also present. The garnet is remarkably free from inclu-

sions.

Another section examined from a specimen collected three and one-half

miles east of Pawling shows a coarse-grained crystalline texture and schis-

tose structure. It is composed mostly of biotite, feldspar, quartz and

garnet. The biotite shows marked pleochroism from light yellowish brown

to deep brown. Only minor amounts of muscovite are present. The feld-

spar consists mostly of plagioclase with some orthoclase. Considerable

quartz is also present. A few small grains of staurolite and a single

erytal of tourmaline were also noted in the section examined.

Going south along the contact of the Dover-Pawling limestone with the

overlying schist, the schist does not vary a great deal in composition, In

places, quartz becomes more prominent and the amount of feldspar in-

creases.

On the north side of the valley at Haviland Hollow, east of Towners, a

dense, dark, finely granitoid rock occurs apparently interbedded with the

mica schists. It is being quarried for road metal. On examination in

thin section under the microscope, the rock is seen to have a granitoid

texture and to consist chiefly of the quartz, plagioclase and hornblende.

The plagioclase gives extinction angles up to 32° 30’ in sections at right

angles to the albite lamelle. Some sections do not show the twinning but

show good cleavage. They are biaxial and optically positive. The plagio-

clase is evidently labradorite. The hornblende shows marked pleochroism

from brownish yellow through deep yellowish brown to dark green. A

little biotite is present. Titanite occurs in considerable amount as acces-

sory mineral. Magnetite and apatite are other accessory constituents

which are present. The rock shows a cataclastic structure, and much of

the quartz is undoubtedly of secondary origin. The mineral composition

indicates an igneous rock of the composition of a quartz diorite. From

252 ANNALS NEW YORK ACADEMY OF SCIENCES

the amount of dynamic metamorphism that it has undergone, it was evi-

dently intruded into the shales now represented by the mica schist prior

to the period of folding as an intrusive sheet.

Pegmatite sheets and dikes become quite abundant in the mica schists

east of the Dover-Pawling Valley. These are usually present in the

form of intrusive sheets and lenses, parallel to the foliation of the schists

which in most cases also represents the bedding planes of this formation.

Dikes also occur. West of the Dover-Pawling Valley, the pegmatites are

not very prominent, occurring only occasionally in the schists just west

of this valley. The tourmaline noticed in one of the sections of phyllite

collected west of the Dover-Pawling Valley was probably ye! from

emanations given off by these pegmatitic intrusions.

HISTORICAL GEOLOGY

As seen from the above description of the formations north of the

Highlands, a sandstone was laid down unconformably upon the upturned

edges of the folded pre-Cambrian gneisses during lower Cambrian time.

Then followed a period of limestone deposition which continued into

Trenton time. Sedimentation was not continuous during this entire

interval, but there were several retreats of the sea followed by re-ad-

vances, so that there are a number of breaks in the limestone represented

by disconformities. These can only be recognized on paleontological

evidence. The limestone deposition was followed by that of a thick

series of dark shales which range in age from Trenton to Cincinnatian.

Then at the close of the Ordovician, there was inaugurated a period of

great orogenic movement, commonly known as the Green Mountain up-

lift. The formations described were thrown into a series of anticlines

and synclines whose axes have a northeast and southwest trend. Accom-

panying this folding, there occurred the intrusion of a large number of

pegmatitic sheets and lenses in the eastern portion of the area, which are

undoubtedly closely related to the granitic batholiths occurring still far-

ther East in Connecticut. The quartz diorite described from Haviland

Hollow, as already mentioned, was intruded prior to the folding.

The burial of these formations to a depth sufficient to bring them into

the zone of anamorphism of Van Hise and the intense pressure accom-

panying the great orogenic movement which produced the folding to-

gether with the injection of a large amount of pegmatitic material had a

marked metamorphic effect upon the formation involved, causing the

limestone in the eastern portion of the area to become completely re-

crystallized and bringing about the formation of numerous lime and

other silicates in it while the overlying shale was converted into a mica

schist.

FETTKE, MANHATTAN SCHIST OF NEW YORK 253

Going west from the Dover-Pawling Valley, the metamorphic effects

become less and less noticeable, until in the vicinity of the Hudson River

fossil remains can still be readily identified in the limestone, and the

shale has hardly been converted into a slate. The transition from a

garnetiferous staurolitic mica schist to a phyllite takes place within a

distance of four and one-half miles in passing from the western margin

of the Dover-Pawling Valley to the eastern side of the Clove Valley.

Such a change in so short a distance can hardly be explained on the

basis of regional metamorphism alone. The axis of most severe orogenic

disturbance runs in a northeast-southwest direction through western

Connecticut and Massachusetts into Vermont. Here the pressure was

greatest, as the folding and crumpling are much more pronounced than

they are farther west where the beds become less disturbed. Along this

line of most severe disturbance a series of granitic intrusions occurred

at the time of the folding. These sent out radiating pegmatitic dikes

and sheets into the adjacent formations which must have had a marked

metamorphic effect upon them and have brought about the recrystalliza-

tion of the constituents of the shale into mica schist as already pointed

out in the case of the Manhattan schist.

Professor Van Hise®* has described a very similar occurrence from the

Black Hills of South Dakota where a great intrusive batholith of granite

is surrounded by sedimentary rocks which are cut by a series of radiating

pegmatitic dikes extending out from the central core. Remote from the

intrusive, the sedimentary rocks are slates, while adjacent to them they

are schists and gneisses.

From the study of the transition of slates to schists north of the

Highlands, the following seems to be the order in which the different

metamorphic minerals were developed. Sericite was the first new min-

eral to form and was accompanied by a partial recrystallization of the

quartz present. The formation of chlorite may have occurred at the

same time. Next biotite began to develop, the iron present in the form

of oxide entering into its composition. Biotite was followed by garnet.

Still later staurolite made its appearance. The sericite by this time had

recrystallized into true muscovite. Feldspar also began to develop at this

stage. As these changes were going on, the texture of the rock was grow-

ing progressively coarser. In the final stages, large quantities of feldspar

appeared, while the muscovite became less abundant, the former develop-

ing at the expense of the latter. In some of these gneissic phases, the

muscovite disappeared entirely. Staurolite also dropped out except for an

occasional grain. The garnet become quite free from inclusions during

these later recrystallizations.

5% U. S. Geol. Surv. Mon. XLVII, p. 724. 1904.

254 ANNALS NEW YORK ACADEMY OF SOIENCES

Faulting has occurred in the region since the period of folding. In

places along the northern borders of the Highlands, the pre-Cambrian

gneisses have been thrust upon the paleozoic strata. - This faulting prob-

ably accompanied the crustal movements which involved eastern North

America at the close of the Paleozoic.

COMPARISON OF INWOOD-MANHATTAN AND POUGHQUAG-W4APPINGER-

Hupson River SERIES

As has already been shown, there is still a marked difference of opinion

as to the relationship of the Inwood-Manhattan series south of the High-

lands to the Poughquag-Wappinger-Hudson River series to the north.

One view is that they are equivalents, while the other is that the Inwood-

Manhattan series consists of much older formations belonging to the pre-

Cambrian. ‘The arguments in favor of their being the same in age will

be taken up first, and then those against such a correlation will be con-

sidered.

Probably the strongest argument in favor of the correlation of the

two series is the fact that they represent almost the same lithological

succession of formations, the only difference being that the one is more

metamorphosed than the other. South of the Highlands, a quartzite is

occasionally found overlying the gneiss, on top of which rests the Inwood

limestone, followed by the Manhattan schist. Naturally, this quartzite

has been correlated with the Poughquag quartzite north of the High-

lands; the Inwood limestone has been regarded as the equivalent of the

Wappinger, and the Manhattan schist has been considered the represen-

tative of the Hudson River slates by many geologists. The upper two

formations in each case correspond quite closely in thickness, but the

Poughquag quartzite on the other hand is usually much thicker than the

Lowerre quartzite south of the Highlands, even where this is developed

to its greatest extent.

From the descriptions of the Hudson River shale and slate and the

Manhattan schist already given, it has been shown that the latter was

derived from a sediment very similar in composition to that of the for-

mer, and where it has been sufficiently metamorphosed, as in the eastern

portion of Dutchess County, it has been converted into a mica feldspar

schist practically identical with the Manhattan schist. Likewise, the

Wappinger limestone of the Dover-Pawling Valley in eastern Dutchess

County also shows the same coarse crystalline texture that the Inwood

limestone possesses and has tremolite and phlogopite developed in it to

an equal extent. faa

FETTKU, MANHATTAN SCHIST. OF NEW YORK 255

A quartz diorite was found occurring at one place in the schist north

of the Highlands which had practically the same relationship to the latter

that the hornblende schist has to the Manhattan schist south of the

Highlands.

The folding of the formations north of the Highlands was also accom-

panied in eastern Dutchess County and western Connecticut, where the

folding was severest, by the intrusion of granites and pegmatites similar

to those south of the Highlands. Those who hold that the two series are

equivalent believe that the orogenic movements which brought about the

folding and metamorphism south of the Highlands were also part of the

Green Mountain uplift which occurred toward the close of Ordovician

time and brought about the metamorphism north of the Highlands. The

axes of the folds in the two regions run in the same general direction.

The occurrence of an area of phyllite south of the Highlands northeast

of Peekskill has been cited as evidence in favor of the Ordovician age of

the Manhattan schist, being regarded by those who hold to the Ordo-

vician age of the schist as a less metamorphosed phase of this formation

which is very similar to the Hudson River slates and phyllites north of

the Highlands. This phyllite has been regarded by all who have studied

it as of Ordovician age.

There is an interval of a little over one and a half miles between the

nearest outcrops of phyllite and schist. As has already been remarked,

where the schist southeast of Peekskill is at a sufficient distance from the

contact metamorphic effects of the Cortlandt intrusive, it does not show as

marked metamorphism as does the typical Manhattan schist farther south

and southeast. Feldspar is almost entirely absent, and sericite is an

abundant constituent of the rock. The schists north of Croton Village

also are not as metamorphosed as the typical Manhattan schist of south-

eastern New York. Some of the garnetiferous staurolite mica schist very

similar to that described from north of the Highlands is also present here.

Clearly transition phases between phyllites and typical mica feldspar

schist similar to those north of the Highlands are present in the area

south of Peekskill and north of Croton Village, but in most cases they

have been obscured by the contact metamorphism accompanying the in-

trusion of the Cortlandt series. As seen from the description of the schist

north of the Highlands, the transition from phyllite to schist may take

place within a comparatively short distance. It is reasonable to believe,

therefore, that the Peekskill phyllite may represent a less metamorphosed

phase of the Manhattan schist.

Of those who have made a careful study of the Manhattan schist, Dr.

Charles P. Berkey®® has given the best arguments against the correlation

53 N. Y. State Mus. Bull. 107, pp. 361-378. 1907.

256 ANNALS NEW YORK ACADEMY OF SCIENCES

of this formation with the Hudson River series He bases his conclusions

upon a number of facts.

One is the relation of the Peekskill Valley quartzite, limestone and

phyllite to the crystalline limestone in the Sprout Brook valley. Dr.

Berkey considers the former to represent a down-faulted block of the

Poughquag-Wappinger-Hudson River strata, as already mentioned, while

the latter, he thinks, is the equivalent of the Inwood, on account of its

thickness and lithological resemblance to that limestnoe, and that it is

not one of the interbedded limestones occurring in the pre-Cambrian

Highland gneisses farther north. In the Peekskill Valley, there are five

hundred feet of quartzite corresponding to the Poughquag quartzite,

while in the Sprout Brook valley the limestone apparently rests upon the

gneiss. This limestone, moreover, is very much more metamorphosed

than that occurring in the Peekskill Valley. All these facts go to show

that they cannot be correlated, and that if the former is the Inwood, the

latter must be later in age.

Another strong argument against such a correlation is that a quartzite

rarely appears between the Inwood limestone and the underlying Ford-

ham gneiss, and where it does occur it is quite thin and can be followed

for only a short distance. Where it is present, it appears to be a part of

the gneiss, as it is conformable with it and apparently grades into it. At

other places, the Inwood lmestone rests conformably upon the Fordham

gneiss. North of the Highlands, on the other hand, the Poughquag

quartzite is usually well developed and reaches a thickness of six hundred

feet in places. It rests unconformably upon the pre-Cambrian gneisses

which Dr. Berkey®® believes are the equivalent of the Fordham gneiss. If

the two series of formations are equivalent, it is hard to understand why

there should be such a marked unconformity north of the Highlands,

while to the south they are apparently conformable. Evidently such a

correlation is impossible che Highland gneisses are of the same age as

the Fordham gneiss of southeastern New York. In this connection, how-

ever, it is interesting to note that in most of the places where the contact

between the pre-Cambrian gneisses and Cambrian quartzites, schists and

conglomerates is exposed in northwestern Massachusetts and western Ver-

mont, the two formations are in apparent conformity.®° There are other

localities in this same region where they are unconformable. The work

of Pumpelly, Wolff and Dale in the Green Mountains of Massachusetts

showed that this conformity was only an apparent one and that the for-

58 Op. cit., p. 361.

©T. NELSON DALE: Structural details in the Green Mountain region and in eastern

New York. U.S. Geol. Surv. Bull. 195, p. 18. 1902.

FETTKE, MANHATTAN SCHIST OF NEW YORK 257

mations were not actually continuous. At one place, two dikes of basic

eruptive rock were found cutting the gneiss but not the overlying quartz-

ite. The eruptive rock had weathered more readily than the gneiss and

depressions were formed which were later filled with pebbles and sand by

the advancing Cambrian sea.*t This proved that the gneisses were of

pre-Cambrian age, while the quartzite and conglomerate were known to

be of Cambrian age from fossils found elsewhere in the neighboring re-

gions. The apparent conformity evidently was only a structural one due

to the general lamination forced upon the rock by the folding.

In the case of the Fordham gneiss, however, parts of which at least are

of sedimentary origin, as shown by the occurrences of interbedded lime~

stone in it, the foliation appears to be parallel to the bedding planes, as

the bands of interbedded limestone are always parallel to the foliation of

the gneiss.

The fact that the phyllite and schist occur so close together in the

vicinity of Peekskill, which has been cited as strong evidence in favor of

the later origin of the former, is not as strong an argument as one might

at first think when we consider that this change does take place within

a not very much greater distance north of the Highlands and also that the

intrusion of the Cortland series must have had considerable effect in

obliterating transition phases if they did occur. As has already been

mentioned, there are still evidences present of what appear to be such

transition phases.

From the above discussion, it is seen that there is still doubt as to the

true age of the Manhattan schist. A much more detailed study of the

geology of southeastern New York State and western Connecticut and

Massachusetts than has yet been attempted will have to be made before a

definite conclusion can be arrived at.

Acknowledgments. The writer is greatly ii.szoted to Professor James

F. Kemp, at whose suggestion this study of the Manhattan schist was

undertaken, and to Professor Charles P. Berkey for many helpful sug-

gestions as the work progressed. The work was carried on in the labora-

tories of the Department of Geology of Columbia University.

&U. S. Geol. Surv, Mon. XXIII, p. 11. 1894.

258 ANNALS NEW YORK ACADEMY OF SCIENCES

BIBLIOGRAPHY

AKERLY, SAMUEL: An essay on the geology of the Hudson River and the ad-

jacent regions; illustrated by a geological section of the country from the

neighborhood of Sandy Hook, in New Jersey, northward through the High

lands in New York, toward the Catskill Mountains. New York, 1820.

BastTIN, Epson S.: Feldspar and quartz deposits of Southeastern New York.

U. S. Geol. Sury. Bull. 315, pp. 394-399. 1906.

: Feldspar deposits of Westchester Co., New York. U. S. Geol. Surv.

Bull. 420, pp. 60-638. 1910.

BERKEY, CHARLES P.: Structural and stratigraphic features of the basal

gneisses of the Highlands. N. Y. State Mus. Bull. 107, pp. 361-378. 1907.

: Areal and structural geology of southern Manhattan Island. Ann.

N. Y. Acad. Sci., Vol. XIX, No. 11, Part II, pp. 247-282. 1910.

: Geology of the New York City (Catskill) Aqueduct. N. Y. State Mus.

Bull, 146:;_ 1914: ‘

BERKEY, CHARLES P., and JOHN R. HEAty: The geology of New York City and

its relations to engineering problems. Municipal Eng. N. Y. C., Pap. No.

62. 1911.

CHAMBERLIN, B. B.: The minerals of New York County, including a list com-

plete to date. Trans. N. Y. Acad. Sci., Vol. VII, pp. 211-235. 1888.

CozZENS, ISSACHAR, JR.: A geological history of Manhattan or New York

Island, together with a map of the Island, and a suite of sections, tables

and columns for the study of geology. New York, 1848.

CREDNER, H.: Geognostische Skizze der Umgegend von New York. Zeits. d.

Deuts. geol. Gesell., Vol. 17, pp. 388-398. 1865.

DaNA, EpwarpD SALISBURY: Hydrous anthophyllite of New York Island. De-

scriptive Mineralogy, 6th ed., p. 398. New York, 1903.

DANA, JAMES D.: Green Mountain geology on the quartzite. Am. Jour. Sct.,

_38rd ser., Vol. III, pp. 179-186, 250-256. 1872.

: On the geological relations of the limestone belts of Westchester

County, New York. Am. Jour. Sci., 3rd ser., Vol. 20, pp. 21-32, 194-220,

359-375, 450-456, 1880; Vol. 21, 1881, pp. 425-448; 1881, Vol. 22, pp. 108-

119, 813-315, 327-835.

: Note on the Cortland and Stony Point Hornblendic and Augite rock.

Am. Jour. Sci., 3rd ser., Vol. XXVIII, pp. 384-386. 1884.

EcKEL, C. E.: The quarry industry in southeastern New York. N. Y. State

Mus. Rep. 54, Vol. I, pp. 145-147. 1900.

GALE, L. D.: Report on the geology of New York County. Geol. Surv. N. Y.,

3d ann. rep., pp. 177-199. 1839.

GRATACAP, L. P.: Geology of the City of New York. New York, 1909.

HALL, JAMES: Report on building stones. N. Y. State Mus. Nat. Hist., 39th

ann. rep., pp. 186-225. 1886.

HAYDEN, H. H.: Description of Granite Ridge crossing New York Island. An

elementary treatise on mineralogy and geology. Cleveland, 1816.

HippEN, W. Earu: Xeno time from New York City. Am. Jour. Sci., 3d ser.,

Vol. XXXVI, p. 380. 1888.

FETTKE, MANHATTAN SCHIST OF NEW YORK 259

Hopss, WILLIAM HERBERT: Origin of the channels surrounding Manhattan

Island, New York. Bull. Geol. Soc. Am., Vol. 16, pp. 151-182. 1905.

: The configuration of the rock floor of Greater New York. U.S. Geol.

Surv. Bull. No. 270. 1905.

Hovey, HE. O.: Notes on some specimens of minerals from Washington Heights,

N. Y. City. Am. Mus. Nat. Hist. Bull., Vol. 7, p. 341. 1896.

HuMPHREYS, EDWIN W., and JULIEN, ALExIS A.: Local decomposition of rock

by the corrosive action of pre-Glacial peat-bogs. Jour. Geol., Vol. XIX,

pp. 47-56. 1911.

IppInes, J. P.: Hornblende schist from Manhattan Island, New York. U. S.

Geol. Surv. Bull. 150, p. 331. 1898.

: Schistose biotite gneiss from Manhattan Island, New York. U. S.

Geol. Surv. Bull. 150, p. 332. 1898.

JULIEN, A. A.: Notes on the origin of the pegmatites from Manhattan Island.

Sci., N. S., Vol. 12, pp. 1006-1007. 1900.

: Genesis of the Amphibole schists and serpentines of Manhattan Island,

New York. Bull. Geol. Soc. Am., Vol. 14, pp. 421-494. 1903.

: The occlusion of igneous rock within metamorphic schists, as illus-

trated on and near Manhattan Island, New York. Ann. N. Y. Acad. Sci.,

Vol. XVI, pp. 387-446. 1906.

Kemp, J. F.: The geology of Manhattan Island. Trans. N. Y. Acad. Sci., Vol.

VII, pp. 49-64. 1887.

: On the Rosetown extension of the Cortlandt series. Am. Jour. Sci.,

8rd ser., Vol. XXXVI, pp. 247-254. 1888.

: The geological section of the East River at 70th St., New York.

rans. N. Y. Acad. Sci., Vol. XIV, pp. 273-276. 1895.

: Pre-Cambrian formations in the State of New York. Cong. Geol. Int.,

Compte Rendu du XI, pp. 699-719. 1910.

KOEBERLIN, F. R.: The Brewster iron-bearing district of New York. Econ.

Geol., Vol. 4, pp. 7138-754. 1909.

LuqQuER, LEA MclI.: Bedford cyrtolite. Am. Geol., Vol. 33, pp. 17-19. 1904.

LuQuUER, LEA Mcl., and HEINRICH RIES: The “augen” gneiss area, pegmatite

veins and diorite dikes at Bedford, N. Y. Am. Geol., Vol. XVIII, pp. 239+

261. 1896.

MacLure, WM.: Geological map of the United States. An elementary treatise

on mineralogy and geology. Cleveland, 1816.

MATHER, W. W.: Report of the geologist of the first geological district of the

State of New York. Geol. Surv. N. Y., second ann. rep., pp. 121-1838. 1888.

: Third annual report of the geologist of the first geological district of

New York. Geol. Surv. N. Y., third ann. rep., pp. 69-134. 1839.

: Geology of New York. Part I. Comprising the geology of the first

geological district. Albany, 1848.

MERRILL, FREDERICK J. H.: On the metamorphic strata of southeastern New

York. Am. Jour. Sci., 3rd ser., Vol. XX XIX, pp. 383-392. 1890.

: The geology of the crystalline rocks of southeastern New York. N. Y.

State Mus., 50th ann. rep., Vol. 1, pp. 21-31. 1896.

: The origin of the serpentines in the vicinity of New York. N. Y. State

Mus., 50th ann. rep., Vol. I, pp. 32-44. 1896.

: Metamorphic crystalline rocks of the New York Quadrangle. Geol.

Atlas U. S., N. Y. C. Folio, No. 83, pp. 3-5. 1902.

260 ANNALS NEW YORK ACADEMY OF SOILENCES

MERRILL, GEORGE P.: Notes on the serpentinous rocks of Essex Co., New York,

from Aqueduct Shaft 26, New York City, and from near Easton, as

vania. Proc. U. S. Nat. Mus., Vol. XII, pp. 595-600. 1890.

NIVEN, WILLIAM: On a new locality for Xeno time, etc., on Manhattan Island.

Am. Jour. Sci., 3rd ser., Vol. L, p. 75. 1895.

NEWBERRY, J. S.: The geological history of New York Island and Harbor.

Pop. Sci. Month., Vol. 13, pp. 641-660. 1878.

: Age of crystalline rocks of New York Island and Staten Island.

Trans. N. Y. Acad. Sci., Vol. I, pp. 57-58. 1881-82.

NEWLAND, D. H.: The serpentines of Manhattan Island and vicinity and their

accompanying minerals. Sch. of Mines Quart., Vol. XXII, pp. 307-317,

399-410. 1901.

: Bedford pegmatite quarry. N. Y. State Mus. Bull. 102, pp. 69-70.

1906.

RIcE, WILLIAM NortTH: Berkshire (Hudson schist). Manual of the Geology

of Connecticut, by William North Rice and Herbert Ernest Gregory. Conn.

Geol. and Nat. Hist. Surv. Bull. No. 6, p. 91. 1906.

Ries, HEINRICH: Note on rock exposure at 143rd Street and 144th Street and

Seventh Avenue, New York City. Trans. N. Y. Acad. Sci., Vol. 10, pp.

113-114. 1891.

Riees, R. B.: The so-called Harlem indicolite. Am. Jour. Sci., 3rd ser., Vol.

XXXIV, p. 406. 1887.

Rogers, G. 8.: Original gneissoid structure in the Cortland Series. Am. Jour.

Sci., Vol. XX XI, pp. 125-1380. 1911.

: Geology of the Cortland Series and its emery deposits. Ann. N. Y.

Acad. Sci., Vol. XXI, pp. 11-86. 1911.

SMITH, J. LAWRENCE, and G. J. BRusH: Hydrous anthophyllite from New York

Island. Am. Jour. Sci. and Arts, Vol. XVI, p. 49. 18583.

Smock, JOHN C.: A geological reconnaissance in the crystalline rock region,

Dutchess, Putnam and Westchester counties, New York. N. Y. State Mus.

Nat. Hist., 39th ann. rep., pp. 166-185. 1886.

STEVENS, R. P.: Report upon the past and present history of the geology of

New York Island. Ann. N. Y. Lyceum Nat. Hist., Vol. VIII, pp. 108-120.

1867.

VAN HISE, CHAS. R., and CHARLES K. en: Pre-Cambrian geology of North

America. U.S. Geol. Surv. Bull. 360, pp. 622-635. 1909.

WHITLOCK, H. P.: List of New York mineral localities. N. Y. State Mus. Bull.

70. 1908.

WILLIAMS, GrorGE H.: Peridotites of the Cortlandt Series. Am. Jour. Sci.,

ord ser., Vol. XXXI, p. 26. 1886.

: The norites of the “Cortlandt Series” on the Hudson River near

Peekskill, N. Y. Am. Jour. Sci., 8rd ser., Vol. XX XIII, pp. 185-144, 191-

199. 1887.

: The contact-metamorphism produced in the adjoining mica schists and

limestones by the massive rocks of the “Cortlandt Series” near Peekskill,

N. Y. Am. Jour. Sci., 8rd ser., Vol. XXXVI, pp. 254-269. 1888.

: The gabbros and diorites of the “Cortlandt Series’ on the Hudson

River near Peekskill, N. Y. Am. Jour. Sci., 3rd ser., Vol. XXXV, pp. 4388-

449, 1888.

PLATE VIII

HORNBLENDE SCHIST AND EPIDOSITE

Fic. 1. Hornblende schist sheet in Manhattan schist.

Near W. 160th Street and Edgecomb Avenue, New York City.

Fig. 2. Epidosite in hornblende schist.

The two middle bands between the light bands are epidosite.

South shore, Croton Lake, New York.

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VOLUME XXIII, PLATE VIII

ANNALS N. Y. ACAD. Sct.

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PLATE IX

PEGMATITE DIKES

' Wig. 1. Pegmatite dike in Inwood limestone.

West 204th Street, east of Sherman Avenue, New York City.

Fie. 2. Banded pegmatite dike in Manhattan schist.

Speedway at Ft. George, New York City.

ANNALS N. Y. ACAD. SCI. VOLUME XXIII, PLAtTH IX

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PLATE X

MANHATTAN SCHIST AND AUGEN GNEISS

Fie. 1. Manhattan schist injected with pegmatite.

Near Rye, Westchester County, New York.

Fie. 2. “Augen” gneiss.

South of Bedford Village, Westchester, New York.

ANNALS N. Y. AcaD. Sci. VOLUME XXIII, PLATE X

PLATE XI

SPECIMENS OF AUGEN GNEISS

| (ce “Augen” gneiss.

South of Bedford Village, Westchester County, New York.

Fie. 2. “Augen” gneiss.

South of Bedford Village, Westchester County, New York.

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ANNALS N. Y. ACAD. SCI. VOLUME XXIII, Puatr XI

Fiq@. 1.

Fig. 2.

Fic. De

Fig. 4.

Fig. 5.

PLATE XII

PHOTOMICROGRAPHS OF GNEISS, SCHIST AND GRANODLORITE

Interbedded gneiss.

Catskill Aqueduct tunnel underneath Harlem River at High Bridge,

New York City.

Magnified 22.5 diameters. Crossed nicols.

Fordham gneiss.

East of High Bridge, New York City.

Magnified 22.5 diameters. Crossed nicols.

Cyanite schist.

West 120th Street, east of Amsterdam Avenue, New York City.

Magnified 22.5 diameters. Crossed nicols. ,

Hornblende schist.

South shore, Croton Lake, New York.

Magnified 22.5 diameters.

Harrison granodiorite.

Greenwich, Connecticut.

Magnified 22.5 diameters,

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PLATE XIII

PHOTOMICROGRAPHS OF SCHIST

. Mica-feldspar-quartz schist.

Southeast corner West 116th Street and Broadway, New York City.

Magnified 22.5 diameters.

. Gray gneissoid variety of schist.

West 42nd Street, near 5th Avenue, New York City.

Magnified 22.5 diameters. Crossed nicols.

. Mica schist.

Verplanck, Westchester County, New York.

Magnified 22.5 diameters. Crossed nicols.

. Mica schist.

North of Croton-on-the-Hudson, Westchester County, New York.

Magnified 22.5 diameters.

. Staurolite mica schist.

North of Croton-on-the-Hudson, Westchester County, New York.

Magnified 22.5 diameters.

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ANNALS N. Y. ACAD. ScI. VOLUME XXIII, PLATE XIII

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PLATE XIV

PHOTOMICROGRAPHS OF PHYLLITE AND SCHIST

Fic. 1. Phyllite.

East of Peekskill Creek Valley, New York.

Magnified 22.5 diameters. Crossed nicols.

Fic. 2. Phyliite.

East of Clove Valley, Dutchess County, New York.

Magnified 22.5 diameters. Crossed nicols.

Fig. 3. Mica schist.

West of Wingdale, Dutchess County, New York.

Magnified 22.5 diameters.

Fic. 4. Staurolite mica schist.

West of Wingdale, Dutchess County, New York.

' Magnified 22.5 diameters. Crossed nicols.

Fic. 5. Mica-feldspar-quartz schist.

East of Pawling, Dutchess County, New York. °

Magnified 22.5 diameters. Crossed nicols.

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PLATE XV

OUTLINE MAP OF SOUTHEASTERN NEW YORK

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