ie ft oo: a wes ‘ ef ; eS a as Bo | Rey Ne. i aN
19 ee SRB i Be ee HES G 2 SPOR, agra’ )\ SAA a a A, = ae 4 nh 4 hates
Aine { wee Se lig “eanane” yrs WS. Qs o , nd Papere _ ~
ie peas a ot eure. ws i w yu Be wie Soe Z
~ : ’ a) . annttna TTT Bava, y bat _
: : 4 ; ag y | Alyy if’ 7
| . Tid 7) LUE AAPA : ul
a eget APEN aR ITNT oe Se
See aa cy “y' r ; eal at at ngs: wa as OT ieee
Maureen in ae a AAG rinse r sea nf The 9d (AA x fant fh Beye, TAIT) Ma Ju,
* a Jf Ya le "Ney so
Wak Lae g wd Wg 4 mig 1] Wr
PORN ec cerer ones uaa Jatin aug we wee 8 mites.
ty Wi. ee ) jn) we a ‘ Siebel a TOR "LoS.
i: a ON i ‘ J "94 e~ 4 wl ow “5
ieee “ora dl " - Herma cctit een at a oan t}. mtr BAT tte
1 be (Seraiie “= weed veeaugt? ee Py ere j pers ] 5 yc ete aay ow nil Very os Ss TEN ‘es
ea Ym vrs A ty, 2+ “dis pus, ~ & < res ee w ae oe 5 W v |
ed Lid Mov © Oe * _ fe Dati if enon ryan tt | is, Ws, N. ann ace
T 1 yr oe. bth rein Ud oa P pease an f ‘ee We * Oyu
Bw Se a pet TS "a 3 ape - i inpy *,. Wu a Ld a vv nade OC @
J -° Ub Sel te Racca: cata eee ad e%y 4 re ‘yr? h 4 Wwe 3 wy ed
Vouue Swe Pri Laer TTT eo9 al a(HAD 4
al 4aager F me eee EEL thas a8 sna ey
pap we wal hy ig
“1 - pe co, ©
» _™
PEPEeee >
Miley :
aé
iw. Dp j pitty Pe: Yoh image iJ
; d edi piban’ i
ee orl hs id past acm
~¥ kK Sk»
FOURNAL OF GEOLOGY
THE UNIVERSITY OF CHICAGO PRESS
CHICAGO, ILLINOIS
Fgents
THE CAMBRIDGE UNIVERSITY PRESS
LONDON AND EDINBURGH
THE MARUZEN-KABUSHIKI-KAISHA
TOKYO, OSAKA, KYOTO, FUKUOKA, SENDAI
THE MISSION BOOK COMPANY
SHANGHAI
KARL W. HIERSEMANN
LEIPZIG
42
ihigls
BOUKNAL OF GEOLOGY
A Semi-Quarterly Magazine of Geology and
Related Sciences
EDITORS
Tuomas C. CHAMBERLIN, 2x General Charge; Roun D, Satispury, Geographic Geology,
SAMUEL W. Wittiston, Vertebrate Paleontology; STuaART WELLER, /nxvertebrate Paleontology;
ALBERT JOHANNSEN, Petrology; Rotiin T. CHAMBERLIN, Dynamic Geology,
ASSOCIATE EDITORS
SrrR ARCHIBALD GEIKIE, Great Brittain; CHARLES Barrois, Prance; ALBRECHT PENCK,
Germany; Hans Reuscu, Morway,; GERARD DEGEER, Sweden; T. W. EpGEwortu Davin,
Australia; Baitey Wit.I1s, Leland Stanford Juntor University; Grove K, GILBERT, Washing-
ton, D.C.» CHartes D, Watcott, Smzthsontan Institution; Henry S. Witiiams, Cornell
University, JosErH P. Ippincs, Washington, D.C.; JoHN C, BRANNER, Leland Stanford
Juntor University; Ricuarp A. F. PENROSE, Jr., Philadelphia, Pa.; WituiaM B. Ciark, Johus
Hopkins Untversity; Witit1am H. Hopss, Uxzverszty of Michigan; FRANK D, Apams, McGill
University; CHARLES K, LEITH, Universzty of Wisconsin; WaLtLacE W. Atwoop, Harvard
University; Witttam H. Emmons, Uzzversity of Minnesota; ArtTHUR L. Day, Carnegie
Iustitution,
VOLUME XXIV
JANUARY-DECEMBER, 1916
e—\sonian Institure My
eo uiEN
THE UNIVERSITY OF CHICAGO PRESS
CHICAGO, ILLINOIS
Published
February, March, May, June, August, September,
November, December, 1916
Composed and Printed By
The University of Chicago Press
Chicago, Illinois, U.S.A.
CONTENTS OF VOLUME XXIV
NUMBER I
Tue AcapiIAn Triassic. PartI. Sidney Powers .
AVERAGE REGIONAL SLOPE, A CRITERION FOR THE SUBDIVISION OF OLD
EROSION SURFACES. Leopold Reinecke
CAIMANOIDEA VISHERI, A NEW CROCODILIAN FROM THE OLIGOCENE OF
SoutH DAKOTA. Maurice G. Mehl
ON THE STRUCTURE AND CLASSIFICATION OF THE STROMATOPOROIDEA.
M. Heinrich
THE PHYSIOGRAPHY OF Mexico. Warren N. Thayer
REVIEWS
NUMBER II
THE AcADIAN Triassic. PartII. Sidney Powers
Notes ON RipprE Marks. J. A.Udden .
PYROPHYLLITIZATION, PINITIZATION, AND SILICIFICATION OF Rocks
AROUND CONCEPTION BAY, NEWFOUNDLAND. A. F. Buddington .
THE ORIGIN OF RED BEeps. A STUDY OF THE CONDITIONS OF ORIGIN
OF THE PERMOCARBONIFEROUS AND TRIASSIC RED BEDS OF THE
WESTERN UNITED STATES. PartlI. C. W. Tomlinson
STUDIES IN HyDROTHERMAL ALTERATION. I, E. A. Stephenson .
ZONAL WEATHERING OF A HORNBLENDE GABBRO. Albert D. Brokaw
and Leon P. Smith .
REVIEWS
NUMBER III
ORVILLE A. DERBY. John C. Branner SVANGRET Me] Reena
TYPES OF PRISMATIC STRUCTURE IN IGNEOUS Rocks. Robert B. Sos-
RTL ATING eae ee Rat by 8 MS Ay lees
ELLipsomaL LAVAS IN THE GLACIER NaTIONAL Park, MOonrTANA.
Lancaster D. Burling . . .
Vv
PAGE
105
123
130
153
180
200
206
209 -
215
235
vl CONTENTS OF VOLUME XXIV
THE ORIGIN OF RED Beps. A STUDY OF THE CONDITIONS OF ORIGIN
OF THE PERMOCARBONIFEROUS AND TRIASSIC RED BEDS OF THE
WESTERN UNITED STATES. PaArTII. C. W. Tomlinson
Tue ACADIAN Triassic. PartTIII. Sidney Powers
Tue LoMBARD OVERTHRUST AND RELATED GEOLOGICAL FEATURES.
Winthrop P. Haynes
THE SKELETON OF Trimerorhachis. S.W. Williston
REVIEWS :
RECENT PUBLICATIONS
NUMBER IV
Note ON THE LINEAR ForRCE OF GROWING CrysTALs. George F.
Becker and Arthur L. Day
Tue CLASSIFICATION OF THE NIAGARAN FORMATIONS OF WESTERN
Oxuto. Charles S. Prosser
ORIGIN OF THE LyMAN ScuHIsts OF NEw Hampsuire. Frederic H.
Lahee
NOTES ON THE DISINTEGRATION OF GRANITE IN Ecyrpt. Donald C.
Barton
A RECORDING MICROMETER FOR GEOMETRICAL Rock ANALysIs. S. J.
Shand Bae:
REVIEWS
RECENT PUBLICATIONS
NUMBER V
THE GEOLOGICAL SIGNIFICANCE AND GENETIC CLASSIFICATION OF
ARKOSE Deposits. Donald C. Barton
AN UnusvuAL Form oF Votcanic Ejecta. Wallace E. Pratt
RrippLE-MARKS IN Onto Limestones. Charles S. Prosser
THe RELATIONSHIPS OF THE OLENTANGY SHALE AND ASSOCIATED
DEVONIAN DEposiIts OF NORTHERN On10. C. R. Stauffer
EVOLUTION OF THE BASAL PLATES IN Monocyc Lic Crinoidea camerata.
I. Herrick E. Wilson
VARIATIONS OF GLACIERS. XX. Harry Fielding Reid .
REVIEWS
RECENT PUBLICATIONS
PAGE
238
254
269
291
298
310
313
334
366
382
394
405
414
417
450
456
476
488
511
515
519
CONTENTS OF VOLUME XXIV
NUMBER VI
THE PRE-WISCONSIN Drirt oF NortH Dakota. A. G. Leonard
EVOLUTION OF THE BASAL PLATES IN Monocyctic Crinoidea camerata.
II. Herrick E. Wilson .
DIFFERENTIATION IN INTERCRUSTAL MAGMA Hee Alfred Harker
STRATIGRAPHY OF THE SKYKOMISH BASIN, WASHINGTON. Warren S.
Smith
“Purr” ConES ON Mount Usu. Y. Gite i
ORIGIN OF FOLIATION IN THE PRE-CAMBRIAM Rocks oF NORTHERN
New York. William J. Miller
THE COMPOSITION OF THE AVERAGE IGNEOUS Roe Adolph Knopf .
REVIEWS
NUMBER VII
Tue GENESIS OF LAKE Acassiz: A CONFIRMATION. W. A. Johnston
THE LOWER EMBAR OF WYOMING AND Its Fauna. E. B. Branson
EVOLUTION OF THE BASAL PLATES IN Monocyctic Crinoidea camerata.
Ill. Herrick E. Wilson
DISCOVERY OF THE GREAT LAKE TROUT, Cristivomer namaycush, IN
THE PLEISTOCENE OF WISCONSIN. L. Hussakof.
ASSUMPTIONS INVOLVED IN THE DocTRINE OF ISoSTATIC COMPENSATION,
witH A NoTE ON HECKER’S DETERMINATION OF GRAVITY AT SEA.
William Herbert Hobbs .
A STAGE ATTACHMENT FOR THE METALLOGRAPHIC Microscope. Albert
D. Brokaw
REVIEWS
NUMBER VIII
Tue ROLE oF INORGANIC AGENCIES IN THE DEPOSITION OF CALCIUM
CARBONATE. John Johnston and E. D. Williamson.
NOTES ON THE STRUCTURAL RELATIONS BETWEEN AUSTRALASIA, NEW
GuIneEA, and NEw ZEaLAnp. E. C. Andrews
A BOotANICAL CRITERION OF THE ANTIQUITY OF THE ANGIOSPERMS.
Edmund W. Sinnott
ARE THE ‘‘ BATHOLITHS” OF THE HALIBURTON-BANCROFT mae On-
TARIO, CORRECTLY NAMED? W.G. Foye .
A CONTRIBUTION TO THE OOLITE PROBLEM. Francis M. Van Tuy!
vil
PAGE
521
533
554
559
583
587
620
623
625
639
665
685
690
718
720
729
751
777
783
792
Vili CONTENTS OF VOLUME XXIV
PAGE
Some EFFECTS OF CAPILLARITY ON Ort AccumuULATION. A. W.
McCoy «30. 60d, SRE ie ite i ee ca ee
A PEcuLtar Process oF SULPHUR Deposition. Y. Oinouye | en
STUDIES FOR STUDENTS. CONTRIBUTIONS TO THE STUDY OF RIPPLE
Marks. Douglas'W. Johnson’ ip "25 52.) 27.) se eee
REVIEWS a) 50 4i5 Spl ee ee ce
Recent PUBLICATIONS « ©.) G00 4) @ap eeaee:, | 2 4 © on
INDEX TO VOLUME XCXTV | 5) (aero eee
ERRATUM
In the article by George T. Becker and Arthur L. Day, published in
No. 4 of Vol. XXIV of this Journal, the following erratum should be noted:
P. 329, line 6 from the top, the word failure is to be replaced by the word
presence.
" SIR ARCHIBALD GEIKIE, Great Britain
se
THE
pane SEMI- QUARTERLY
EDITED BY
THOMAS GC. CHAMBERLIN AND ROLLIN D. SALISBURY ™&
With the Active Collaboration of
“VOLUME XXIV _ | atu oti NUMBER 1
OURNAL oF GEOLOGY,
a csonian aa
35042
“ “ee 6
Nationa Muses
SAMUEL W. WILLISTON ALBERT JOHANNSEN
Vertebrate Paleontology _ Petrology
STUART WELLER ROLLIN T. CHAMBERLIN
Invertebrate Paleontology ; Dynamic Ge
ASSOCIATE EDITORS
JOSEPH P.IDDINGS, Washington, D.C.
~ HENRY S. WILLIAMS, Comell University ARTHUR L. DAY, Carnegie Institution
JANUARY-FEBRUARY 10916
oo ee CHICAGO, ILLINOIS, U.S.A.
AGENTS
THE CAMBRIDGE UNIVERSITY PRESS, Lonpon anp EDINBURGH
KARL W. HIERSEMANN, LErrzic
THE MARUZEN-KABUSHIKI-KAISHA, Toxyo, Osaka, Kyoto
CHARLES BARROIS, France JOHN C. BRANNER, Leland Stanford Junior University
ALBRECHT PENCK, Germany ~ RICHARD A. F. PENROSE, Jr., Philadelphia, Pa.
_ HANS REUSCH, Norway WILLIAM B. CLARK, Johns Hopkins ayers
GERARD DEGEER, Sweden : WILLIAM H. HOBBS, University of Michigan
_ T.W. EDGEWORTH DAVID, Australia FRANK D. ADAMS, McGill University
BAILEY WILLIS, Leland Stanford Junior University CHARLES K. LEITH, University of Wisconsin
' GROVE K. GILBERT, Washington, D.C. WALLACE W. ATWOOD, Harvard University
CHARLES D. WALCOTT, Smithsonian Institution WILLIAM H. EMMONS, University of Minnesota
27
47
THE ACADIAN TRIASSIC. PART I - - - - - - - SIDNEY POWERS
AVERAGE REGIONAL SLOPE, A CRITERION FOR THE SUBDIVISION OF OLD —
-' EROSION SURFACES 2 ORRIN S Ge AES PO iy ee Shee ehh Ee OP OED RO ENE GCE
‘ ‘CAIMANOIDEA VISHERI, A NEW CROCODILIAN FROM THE OLIGOCENE OF
SOUTH DAKOTA EERE STE SSNS Le Ra a eae SRR re IVE EEE,
_ ON THE STRUCTURE AND CLASSIFICATION OF THE STROMATOPOROIDEA
M. HEINRICH
cnn PHYSIOGRAPHY OF MEXICO ek Oe es Warren N.- THAYER
ee
oe OPE UNIVERSITY OF. CHICAGO: PRESS
Z ian teases
sxwsontan Stil,
o
g. P. Iddings
¥ COLLECTION y
atonal mused™
Che Journal of Geology —
Vol. XXIV CONTENTS FOR JANUARY-FEBRUARY 1936 No. 4
THE ACADIAN TRIASSIC. PARTI = =) =) 05 thi ie ee ee OS = = OSIDNEY “PowERs©
AVERAGE REGIONAL SLOPE, A CRITERION FOR THE SUBDIVISION OF OLD EROSION SURFACES
LEOPOLD REINECKE 27
CAIMANOIDEA VISHERI, A NEW CROCODILIAN FROM THE OLIGOCENE OF SOUTH DAKOTA
! AURICE G. MEHL 47
ON THE STRUCTURE AND CLASSIFICATION OF THE STROMATOPOROIDEA- - -_ - M. Hemneice 57
THE PHYSIOGRAPHY OF MEXICO) nooo = iahie! Uae ee a) ie hee oe en WAR, Nie
REVIEWS.) om) cit opi dt logue tad Syelle Re sel iizln’ pilhea Blac Spdees is mst eileen Sdn 40 ket eve
The Journal of Geology is published by the University of Chicago at the University Press semi-
quarterly, on or about the following dates: February 1, March 15, May 1, June 15, August 1, September 15,
November 1, December 15. {| The subscription price is $4.00 per year; the price of single copies is
65 cents. Orders for service of less than a half-year will be charged at the single-copy rate. ‘] Postage is
prepaid by the publishers on all orders from the United States, Mexico, Cuba, Porto Rico, Panama Canal
Zone, Republic of Panama, Hawaiian Islands, Philippine Islands, Guam, Samoan Islands, Shanghai.
{| Postage is charged extra as follows: For Canada, 30 cents on annua! subscriptions (total $4.30), on
single copies, 4 cents (total 69 cents); for all other countries in the Postal] Union, 53 cents on annual
subscriptions (total $4.53), on single copies, 11 cents (total 76 cents). ] Patrons are requested to make
all remittances payable to the University of Chicago Press in postal or express money orders or bank
drafts.
The following agents have been appointed and are authorized to quote the prices indicated:
For the British Empire: The Cambridge University Press, Fetter Lane, London, E.C. Yearly
subscriptions, including postage, 18s. 8d. each; single copies, including postage, 3s. 2d. each.
For the continent of Europe: Karl W. Hiersemann, KGnigstrasse 29, Leipzig, Germany. Yearly
subscriptions, including postage, M. 22.65 each; single copies, including postage, M. 3.80 each.
For Japan and Korea: The Maruzen-Kabushiki-Kaisha, 11 to 16 Nihonbashi Tori Sanchome,
Tokyo, Japan. Yearly subscriptions, including postage, Yen 9.00 each; single copies, including
postage, Yen §.50 each.
Claims for missing numbers should be made within the month following the regular month of
publication. The publishers expect to supply missing numbers free only when they have been lost in
transit.
Business correspondence should be addressed to The University of Chicago Press, Chicago, Ill.
Communications for the editors and manuscripts should be addressed to the Editors of THE
JOURNAL OF GEOLOGY, the University of Chicago, Chicago, Ill.
Contributors are requested to write scientific and proper names with particular care and in citations
to follow the form shown in the pages of the Journal.
Separates, if desired, must be ordered in advance of publication. Separates of leading articles will be
printed as ordered, of which 50 (without covers) will be furnished grafis, the actual cost of the remainder
(and covers, if desired) to be paid for by the author. The actual cost may vary, and will depend upon
the amount of work in re-making the pages into forms, presswork, paper, binding, etc. Separates
containing half-tones may be expected to cost somewhat more, the increase depending upon the number
of cuts and the amount of work required upon them.
Entered as second-class matter, March 20, 1893, at the Post-office at Chicago, III., under the Act of March 3, 1879,
VOLUME XXIV NUMBER 1
THE
fOURNAL OF GEOLOGY
JANUARY-FEBRUARY 1916
THE ACADIAN TRIASSIC
SIDNEY POWERS
Troy, New York
CONTENTS
PART I
INTRODUCTION
General Relations
’ General Geography and Geology of the Region
Topography
Geology
THe NEWARK GROUP IN THE ACADIAN AREA
DESCRIPTIVE GEOLOGY
Stratigraphy
Grand Manan
Split Rock
Quaco
Martin Head
Waterside
Advocate Harbour
Cape Sharp
Partridge Island
Greenhill—Five Islands
Five Islands
Vol. XXIV, No: 1 I
2 SIDNEY POWERS
PART II
Gerrish Mountain
Gerrish Mountain—Truro
Truro—Wolfville
Wolfville-Scots Bay
Scots Bay—Bennetts Bay
Digby Gut <
Rossway—Brter Island
Age
PART III
STRUCTURE
Folds
Faults
Theories of Origin
IGNEOUS Rocks
Distribution
Five Islands Volcanics
North Mountain Basalt
ORIGIN
PART I
INTRODUCTION
GENERAL RELATIONS
The Acadian Triassic is preserved as a rather narrow, discon-
tinuous border to the Bay of Fundy and Minas Basin. The Bay
of Fundy has a northeast-southwest trend, with the island of Grand
Manan at the entrance. The Triassic extends from the southwest
end of Grand Manan to Truro, a distance of 195 miles. The width
of the Bay of Fundy, from Digby to St. John, is 45 miles. On both
the New Brunswick and the Nova Scotia shore, the Triassic appears:
in New Brunswick on Grand Manan Island, at Split Rock (Gard-
ner’s Creek), Quaco, Martin Head, and Waterside; in Nova Scotia
on the island of Isle Haute, and in a quite continuous strip from
Advocate around Minas Basin and down the Bay of Fundy to
Brier Island at the entrance.
The field work in connection with this paper occupied a portion
of the summers of 1913 and 1914. In the field work, the writer
is indebted for suggestions to Professor J. W. Goldthwait, Dr.
THE ACADIAN TRIASSIC 3
A. O. Hayes, and Mr. W. A. Bell of the Geological Survey of
Canada, and to Professor D. S. McIntosh of Halifax, Nova Scotia.
Professor Alfred C. Lane of Tufts College has kindly permitted the
use of thin sections and drill cores of the Cape D’Or basalt. To
Professor R. A. Daly, under whose direction this paper was pre-
pared as a portion of a thesis for the degree of Doctor of Philosophy
in Harvard University, special thanks are due for helpful criticism.
GENERAL GEOGRAPHY AND GEOLOGY OF THE REGION
Topography—tThe most important topographic feature of the
Bay of Fundy region is North Mountain, extending from Cape
Blomidon to Brier Island, 125 miles. South of North Mountain
is the Annapolis Valley and the land of Evangeline, a broad fertile
plain extending from Minas Basin to the Annapolis Basin. South
of the Annapolis Valley is South Mountain, whose crest stands
on a level with North Mountain, at an elevation of about
Aoo feet.
On the northern side of the Bay is the island of Grand Manan,
' presenting an abrupt escarpment on the west, rising 200 to 4oo feet
out of the sea. The tops of these basaltic cliffs is again at the
level of North Mountain. On the east side of Grand Manan is a
rolling lowland fronted by many islands. The New Brunswick
shore is bounded by rocky cliffs rising to a height of 50 to 200 feet,
but between the Triassic exposures at Quaco and Waterside, the
clifis rise to the summit level of 400 feet.
Minas Basin is surrounded by lowlands, presenting a rather
flat surface at elevations of 100 to 150 feet, except for the tidal
marshes. On the north, the Cobequid Mountains rise to heights
of 500 to 800 feet, with “peaks”’ at 1,000 feet.
Geology.—The controlling factor of the topography and geology
of the region is the direction of the orographic axes, from north-
east to southwest (Fig. 1). The Bay of Fundy is confined between
a broad belt of pre-Cambrian rocks in Nova Scotia, fronted by the
Triassic; and a less broad belt of pre-Cambrian rocks in New Bruns-
wick, fronted by Carboniferous and Triassic strata (Fig. 2). The
peninsula of Nova Scotia is composed largely of pre-Cambrian
strata intruded by Devonian granite.
4 2 SIDNEY POWERS
Minas Basin is bounded by Triassic rocks, below and around
which are Carboniferous and Permian strata. To the north,
separated by a normal fault, are the Cobequid Mountains, which
are composed of Silurian schists and quartzites with various
AEA
ENG ONNECTICUT_VALLEY AREA
ae
POMPERAIUG AAR
iN
x y
PS
ee
vi x << We
Some y
TRIASSIG AREAS
sansounshusancns™ TANG 7 EASTERN NORTH AMERICA
tee ° fea UW AREA Based on Maps hy
ta Cit Anca RUSSELL AND HOBBS
ie AR Wn ye Veep P
SCALE is
$0 o 400 200 360 mites,
Aeproduced from Bull. 6, Connecticur
Geological and Nawwraf History Survey
with modifications by Sidney Fowers
Frc. 1.—The Newark group in North America
associated igneous rocks. North and west of the Cobequids are
' Carboniferous and Permian strata, stretching northward over the
Magdalen Islands and over Prince Edward Island.
THE NEWARK GROUP IN THE ACADIAN AREA
The first reference to the Triassic in the Maritime Provinces
is by Alger, in 1827.7 Six years later, a description of the Triassic
«F. Alger, ‘““Notes on the Mineralogy of Nova Scotia,” Am. Jour. Sci., XII (1827),
THE ACADIAN TRIASSIC
rocks was published by Jackson and Alger.’
At about that time Gesner began his work in
connection with the Geological Survey of New
Brunswick and mentions the Triassic in each
of his reports.’
From 1835 to the present, a number of
writers have discussed the Acadian Triassic
in part or in whole, and, as Russell has given
a bibliography of these papers in his corre-
lation paper on “The Newark System,’ only
the more important and the recent papers
need be noted here.
Dana gave the name “Acadian Area”’ to
this mass of Triassic rocks in his Manual of
Geology (2d ed., 1875). Three years later,
Dawson issued the second edition of his
Acadian Geology, in which volume is the only
account of the Triassic in Nova Scotia and
New Brunswick. From 1863 to 1880, G. F.
Matthew and L. W. Bailey were employed by
the Geological Survey of Canada in mapping
southern New Brunswick. In their reports
are descriptions of the outliers of Triassic’
strata in New Brunswick.
The more recent work on the Acadian
Triassic is that published by L. W. Bailey
on the Digby Neck region‘ and by H. Fletcher
tC. T. Jackson and F. Alger, ‘““Remarks on the
Mineralogy and Geology of Nova Scotia,’ Am. Acad.,
Mem., N.S., 1, 217-330.
2The reports are given in the bibliography of all
literature on the Newark System, in I. C. Russell’s corre-
lation paper on “The Newark System,” U.S. Geol. Surv.,
Bull. 85, 1892.
3 [bid.
4L. W. Bailey, “Report on the Geology of South-
western Nova Scotia,” Geol. Surv. Canada, Ann. Rept.,
IX (1898), Part M.
Fic. 2.—Geologic cross-section, AA, of the entrance to the Bay of Fundy, through Quoddy Head, Maine, on the northwest, the
island of Grand Manan near by, and Long Island on the southeast.
Diabase (Devonian ?); 7, Triassic.
P, pre-Cambrian; B, Meguma series (pre-Cambrian); S, Silurian; D7,
The Triassic shales under the basalt on Grand Manan appear only on the north. The Triassic sedi-
ments south of Long Island are submerged. Note the longitudinal valley on Long Island between the flows.
6 SIDNEY POWERS
who mapped the Minas Basin region" for the Geological Survey
of Canada.
The former extent of the Acadian area is indeterminate, but
it is probable that it extended several miles in all directions beyond
the present boundaries. The original form appears to have been a
basin with its northern limit near the Cobequid Mountains and its
southern limit not far south of Grand Manan and Brier Island.
There may have been a ridge of older rock extending out into the
basin where the eastern side of Grand Manan now is, provided that
the interpretation of the geology of that island, as given below, is
correct. :
The Newark group in the Acadian area has been divided into
the following formation:
Thickness in Feet
Top, an erosion surface
Scots Bay formation (calcareous white sandstone)............ 25-(2,000 ?)
North Mountain basalt (a succession of lava flows) .......... 800-— 1,000
Annapolis formation (red beds, largely calcareous)
Blonudantshales 3 2h s..-27 500- 1,000
Wolfville sandstone........ 2,000— 2,500
3,325- 6,500
Base, an unconformity with Paleozoic or older rocks
Interbedded in the Annapolis formation, near its top, are certain
basalt flows: agglomerate and tuff beds near the Five Islands,
grouped under the name Five Islands volcanics. At Quaco,
New Brunswick, there is a conglomerate horizon in the center of
the red sandstones correlated with the Annapolis formation, and
this conglomerate is called the Quaco conglomerate.
DESCRIPTIVE GEOLOGY
The descriptive geology of the Acadian Triassic will be taken
up by localities, giving a brief description of the lithological and
structural details. A number of detailed maps and sections are
introduced, which may be connected with the region as a whole, by
reference to the general map (Fig. 3), and the columnar sections
« H. Fletcher, various papers which have been printed in the annual and summary
reports of the Geological Survey of Canada from 1887 to 1907. See especially the
Annual Report, V (1892), Part P.
THE ACADIAN TRIASSIC 7
(Fig. 4). The principal
structural features and the
details concerning the igne-
ous rocks are summarized
in a separate section.
(TM sonra mounrarm ease
EZ AAAnwaronis FORMATION
[oJ SCQTS BAY FORMATION
LECEND
ACADIAN TRIASSIC
STRATIGRAPHY
Grand Manan.— The
island of Grand Manan is
situated 4 miles southwest
of Quoddy Head, the most
easterly point in the Uni-
ted States. It is 15 miles
long and 6 miles wide in
the widest part. To the
east and south are numer-
ous islands and reefs.
Grand Manan was first
visited by a _ geologist—
Abraham Gesner—in 1838,
then by Bailey,’ Verrill,?
and Ells. Bailey visited
most of the adjoining
islands and gives the best
description of the geology.
tL. W. Bailey, “The Physiog-
raphy and Geology of the Island of
Grand Manan,’ Can. Nat., VI
(1872), 43 ff.; also see Bailey,
Matthew, and Ells, “‘ Preliminary
Report on the Geology of Southern
New Brunswick,” Geol. Surv.
Canada, Rept. Progress (1870),
pp. 216-21.
2A. E. Verrill, Appendix E to
Dawson’s Acadian Geology, 3d ed.
(1878), pp. 679-80.
3R. W. Ells, Geol. Surv. [Pr sacr
Canada, Summary Rept., VIII
(1894), 271A. ~
a
>
3S
=
S
x
:
3
z
Fic. 3.—Map of the Acadian Triassic
SIDNEY POWERS
4204 dG
o20Nf)
ISSVLL, ULIPRIY dy} JO SUIS AvULUNJOO—F “Oly
4794 o001
_—SSEaE——]ase
31VIS
JISSWIYL NYIGVOV
3HL IO
SNOILIAS YVNNNIO9
S21U02/0A
spuvjs} aaly
Spuvjs| aary 40,9 2409 Uouvpy pussy Aomssoy
JISSVIVL- Jud
auojspuog
atAFIOM
>
2
2
>
v
SS
Ps
a
3
>
Es
>
Fa
3
2
2/04
vopiwojq
LIVSVE NIVINNOW
H1LYON
NOILUWH OF
AVG SL109S
hog s102S
~9/[IA$[OM
THE ACADIAN TRIASSIC
SVaIv OISSVIT], ‘prop UAL pur ‘oovn?y “yooy qyds oy} jo de
sap Ss
SSS SS SSS SSI
W—'S ‘oly
DI8SVI ws
MIOW LITIS
\
@
~-K Ws
ie) SIDNEY POWERS
The physiography and geology of Grand Manan divide the
island into two provinces: a western upland underlain by Triassic
basalt flows, and an eastern lowland underlain by pre-Silurian’
metamorphic rocks. The upland represents the level of the
Summit? peneplain, at elevations of 200-400 feet. The western
coast of the island is fronted by cliffs rising abruptly in an almost
straight line to a height of 100-300 feet.
The Triassic rocks of the island consist of basalt flows under-
lain by purple shale. The shale is exposed to a thickness of only 50
feet, and this exposure is at Dark Harbour, on the western side of
the island. The basalts rest directly on older, metamorphic rocks
on the eastern side of the island; at Red Head, on the south, and
at the northwestern end of Flag Cove, on the north. At the
former locality the contact dips 35 degrees, suggesting a fault, but
the recent weathering of the rocks near the contact obscures the
exposure.
The basalt flows are thick at the base and thin at the top. The
exact thicknesses are given below with the résumé of the igneous
rocks. The dip of the flows is variable. At Dark Harbour it is
practically horizontal, but north of this place, the dip is down toward
the north at angles of 5 to 15 degrees. It is difficult to determine
the horizontal extent of any one flow. Diabase dikes are reported
by Bailey at several places, one of which is Swallow-Tail Light.
The faults on Grand Manan are obscured by the massive
character of the basalt. The major fault bounds the west side of
the island, and the cliffs, which run in an almost straight line for
15 miles, mark the fault-line scarp. East-west faults are less
prominent. One may occur at Dark Harbour, as many of the
streams flowing across the Newark basalts follow fault-lines. Minor
faults are seen in the shore exposures. ji
Split Rock.—Eighteen miles east of St. John, between Gardner’s
Creek and Tynemouth Creek, there is a strip of Triassic sediments
«The age of these rocks is probably pre-Cambrian, as they are older than the
Silurian rocks of the Eastport Quadrangle. See E. S. Bastin, U.S. Geol. Survey,
Geol. Atlas, Eastport Folio (No. 192) (1914), p. 14.
2 The term “Summit” peneplain is used instead of “Cretaceous”’ peneplain in
order to avoid any reference to the age of this topographic feature.
THE ACADIAN TRIASSIC II
about two miles long, and three-quarters of a mile wide at Split
Rock itself (Figs. 5 and 6). This point should not be confused
with one southwest of St. John by the same name.
This area is bounded on the north by a fault which has brought
the Triassic into contact with the Carboniferous. The dip of the
Fic. 6.—The Triassic shales near Gardner’s Creek (Split Rock), dipping north-
ward. The marine shelf has been cut at high tide level.
Triassic red sandstones, shales, and occasional conglomerates is in
general northward at angles of about 45 degrees, but the beds
flatten out at split rock itself. The sediments show occasional
cross-bedding. The conglomerates contain only occasional pebbles,
and these pebbles are subangular, with occasionally very angular,
and rarely rounded surfaces. They do not show striations or
sand-blasted surfaces. Fragments of silicified wood have been
found near Gardner’s Creek, and are noted by Dawson in his
Acadian Geology.
12 SIDNEY POWERS
Quaco.—A large area of Triassic sediments occurs at Quaco,
now known as St. Martin. The Triassic extends from West
Quaco to Melvin’s Beach, and includes the large area mapped as
Fic. 7.—Geologic cross-section, BB, from Quaco, on the north, through North
Mountain, the Annapolis Valley, and South Mountain, on the south. 4A, pre-
Cambrian; D, Devonian; Gr, Devonian granite; T, Triassic.
Fic. 8.—The contact of the lower red sandstone and the Quaco conglomerate
above, near Macomber Brook, Quaco. The contact is a conformity. There is a
very sharp boundary both in lithology and in color which is obscured by a pile of talus
in the center of the picture. °
Lower Carboniferous on the map of the Geological Survey of
Canada, issued in 1880. The length of the area is 73 miles and
the width 3 miles, as shown in Fig. 5. The shore exposures furnish
an excellent structural cross-section of the area.
THE ACADIAN TRIASSIC 13
The structure of the Quaco area is synclinal, with an east-west
axis (Figs. 7 and 8). The contact of the Newark rocks with older
rocks is shown at West Quaco, where there is an unconformity of
red Triassic sandstone on greatly pointed, pre-Triassic traps.
The basal sandstone contains occasional pebbles of various kinds
of rock but contains no residual soil of the trap. At the uncon-
formity there is minor cross-faulting in a northeasterly direction.
At Melvin’s Beach, on the northeast, the Triassic sandstones are
seen, with steeply dragged dips, in fault-contact with pre-Cambrian
metamorphics.
The stratigraphy of the area shows two normal red sandstone
members, separated by a conglomerate of pale yellow color. Inter-
bedded in the conglomerate are persistent beds of sandstone, a few
inches in thickness, at stratigraphic distances of 10-30 feet, as
shown in Fig. 8. The conglomerate is composed of rather loosely
consolidated subangular to rounded stream gravels. Many of the
pebbles show impressions of one pebble into another, and other
recemented fractures. In no other locality of the Acadian Triassic
is such a conglomerate found.
The section was estimated as follows:
Wppenmedisandstomencn Wit) ee a ccisn ee 800-1,000+
@uacorconglomeraten gy sae aualsles orale 450- 700
Wowermnedssandstonem ne ah, oye cnn ie) 300—- 300
T,550—-2,000
UNCONFORMITY WITH CARBONIFEROUS
Plant remains occur at several horizons in the Quaco series.
Silicified wood was found by the writer within 50 feet of the top
of the lower red sandstone, at Vaughan Creek, and by members
of the Geological Survey of Canada at other localities. These
fossils are correlated with the fragments of lignite from Split Rock
and Martin Head. On account of the exposure of the basal uncon-
formity of the Newark at West Quaco, it is probable that the
Quaco exposure is to be correlated with the Annapolis formation,
t These conglomerates are similar to those of Upper Devonian age on the north
side of Scaumenac Bay, Province of Quebec, described by J. M. Clarke, Bull. Geol.
Soc. Am., XXVI (1015).
14 SIDNEY POWERS
and that it is below the horizon of the North Mountain basalt, as
shown in Fig. 4.
Martin Head—Martin Head is 20 miles northeast of Quaco.
The Head itself is composed of a mass of pre-Cambrian strata,
too feet in height, connected to a point of land by a shingle beach
(Fig. 9). On the northern side of the Head is some red clay,
apparently of Pleistocene age, which may be underlain by Triassic
sediments.
North of the barrier beach are low cliffs of Triassic strata,
exposed only on the west side of the peninsula. The bedrock is
exposed for half a mile in the form of a syncline, with the longer
Fic. 9.—Cross-section of the Martin Head Triassic area. Martin Head itself,
composed of pre-Cambrian strata, is on the right. Between it and the pre-Cambrian
uplands on the northwest are the Triassic sediments. The unconformable contact
of the Triassic with the pre-Cambrian on the southeast is hypothetical.
limb on the south. On the north, the Triassic is faulted against
the pre-Cambrian, as shown in Fig. 9. In the southern limb 335
feet of sediments are exposed, in the northern limb 85 feet, and
between these two limbs there are no exposures. A fault probably
exists between the exposures, as the strata do not match on either
side of the gap.
The sediments in the Martin Head area are principally yellow
sandstones and shales, with occasional pale-red beds, and transition
colors. The yellow is a bright-chrome shade, much brighter than
that of the Quaco conglomerate, which is merely that of the common
stream gravels. Conglomeratic beds occasionally appear. The
sediments are characterized by a notable amount of muscovite
and of calcite. The former has evidently been derived from the
pre-Cambrian mica schists on the north.
Lignite occurs at several horizons in the yellow beds, as car-
bonized twigs, limbs, and bits of wood, often 2—3 inches in diameter.
This lignite has been described by Miss Ruth Holden,’ and the
* Ruth Holden, “Fossil Plants from Eastern Canada,” Annals of Botany, XXVII
(1913), 243-55.
THE ACADIAN TRIASSIC 15
paper is summarized below in treating of the age of the Acadian
Triassic. As the plant remains appear to be similar to those found
at Quaco, the sediments in the two areas may be correlated with
each other.
Waterside —On the north side of Chignecto Bay is a strip of
Triassic at Waterside, 20 miles northeast of Martin Head. The
length of the strip is
about 4 miles, ex-
tending from Den-
nis’ break-water on
the west to the east-
ern end of the marsh
at Little Rocher on
the east (Fig. 10),
but the length of the
actual exposures of
Triassic sediments is
about 14 miles.
The structure of
this area is anticlinal
on the west and synclinal] on the east, with the axis of the syncline
at the Waterside wharf. The dip of the folds is gentle, exposing
only 320 feet on the eastern limit of the anticline. On the west,
Fic. 1o.—Map of the Waterside area of Triassic
sediments.
T c sD C T 18 D =B
\
Cn
Fic. 11.—Geologic cross-section, CC, from Waterside, on the north, through
Cape d’Or, across Minas Channel, and through North Mountain. A, pre-Cambrian,
B, Meguma series (pre-Cambrian); SD, Cobequid group (Silurian, cut by Devonian ~
igneous rocks); D, Devonian; C, Carboniferous; 7, Triassic. The major fault of
the region is shown in the center of the section, where the Carboniferous and Triassic
are dropped down against the Cobequid group.
the Triassic is faulted against a sheared Carboniferous conglomer-
ate, but the contact is concealed by a Pleistocene delta deposit.
This same fault probably bounds the Triassic area on the north
and east, but it is not again exposed.
SIDNEY POWERS
16
The Waterside Newark strata consist of pale-red sandstones
with occasional conglomerates.
At the top of the series there are
voIv 10.P adej-o}eo0Apy oy} Jo depy—*z1 “OL
See
syjney
Bjoy-a00g x
NYIYNTS
suosepuog [ ]
NWINYATASNNIA
“WMAoy syodouuy Res
ANOGAD,
sie) AIPSOD YW YL4°A/ ae
ap,OIOAPY e
IISSVIUL
SN NN NN
ee SS a \
S\ a4 b20004 \
SS SO QNIDI7I
PHOT p2yig
EN
NEN
to peculiar
several calcitized sandstone beds, which weather out in
Persistent thin green shale or sandstone beds are present.
forms.
THE ACADIAN TRIASSIC 17)
Contemporaneous erosion channels are seen west of the Waterside
wharf.
The Waterside section is to be correlated with the Annapolis
formation, but, as no plant remains have been found in it, a more
definite correlation is impossible.
Advocate Harbour—At the southeastern end of Minas Basin
is Cape d’Or and north of it is Advocate Harbour. The shore from
Cape d’Or to Cape Spencer (Figs. 11, 12) is fronted by basalt
FARTRIOGE Is.
LEGEND
North Mt. Basalt
Annapolis Form.
TRIASSI |
Fic. 13.—Map of the Cape Sharp-Partridge Island region
cliffs too feet or more in height. The lowlands on the north are
underlain by Triassic sandstone, and, farther north, by Carbonif-
erous sediments. . North of the latter are the Cobequid Mountains,
fronted by a fault-line scarp rising abruptly from the lowlands.
The upland from Cape d’Or to Cape Spencer, and the islands,
Isle Haute and Spencer Island, are composed of basalt flows dipping
southward at a low angle. Five flows are exposed at Cape d’Or
in drill-cores. The base of the flows rests on Newark shale and
sandstone of a white or red color. Both the basal amygdaloid and
the underlying sediments are penetrated by gypsum veins.
North of Cape Spencer, very coarse conglomerates, which are
probably of Newark age, are exposed. The bowlders in this con-
glomerate are a foot or two in diameter.
On the shore near West Advocate is the only other exposure
of Newark sediments in this area. Red sandstone, with some red
18 SIDNEY POWERS
shale, and thin greenish or white bands of sandstone, are dipping
eastward. Adjoining these sandstones, on the north, is Silurian
carbonaceous schist of the Cobequid group, separated by a fault
which may be traced down the beach in a S. 71° W. direction.
This is the main Cobequid fault, shown in Fig. 10. Other minor
faults are shown in the same map. Ep
Fic. 14.—Partridge Island from the west, showing basalt flows overlying red
sandstones. The sandstones appear along the gentle slope at the left-hand side of the
cliff.
Cape Sharp.—To the east of Cape Spencer, Cape Sharp is the
first promontory. It consists of basalt, as does Black Rock on
the west (Fig. 13). On the north of Cape Sharp is a lowland
underlain by red Triassic sandstone and shale with occasional green
bands, and north of this is a rolling country underlain by Carbonif-
erous sediments.
The basalt on Cape Sharp consists of one or more flows—
probably two flows—which dip to the south at an angle of about
ug)
THE ACADIAN TRIASSIC
UOISII Spurs] OMT, 9y} Jo def{—'s1 “OI
SapliWs ;
ITVIS
HOUOUIIOS syodouuy SS
DISSYIUL Q
SIIUOIY spug/sy aAly POAT SONV7SI OML
nN
SING UHOSSDM
20 SIDNEY POWERS
~\2)
5-10. The shale and sandstone underlying the basalt are exposed
on the northeast side, for a short distance only. The sandstone
Frc. 16.—Structure section, G, through Clarke’s Head, on the south, and Swan
Creek, on the north. The structure of the pre-Triassic rocks isnot shown. Overlying
the Triassic red sandstone is a bed of tuff, overlain, in turn, by agglomerate. At Swan
Creek only agglomerate appears, but it 1s probably a part of the same flow.
Fic. 17.—A detailed view of the agglomerate which comprises a large portion
of the Five Islands volcanics. The photograph shows the center of a 1oo-foot bed
of the agglomerate east of Blue Sack. The angular blocks are composed of basalt, and
the matrix is tuffaceous.
is seen to be in fault contact with the Carboniferous shales and
sandstone to the north.
Partridge Island——East of Cape Sharp is a peninsula called
Partridge Island, formed of a mass of basalt connected with the
THE ACADIAN TRIASSIC
shore by a low, swampy area which is
covered by the sea at very high tides.
On the northwest is Gilbert’s Cliff, rising
to a height of 60 feet, and on the northeast
Parrsboro Pier (Fig. 13).
The basalt on Partridge Island (Fig. 14)
is partly columnar and partly vesicular. It
probably consists of two flows. Stilbite is
very abundant in geodes in the amygdaloid.
At the base of the lower flow the highly
weathered amygdaloid is 15 feet thick.
The Triassic shales and sandstones are
seen underlying the basalt on the west
side of the island, dipping southward at an
angle of.10 to 35 degrees. . Near Gilbert’s
Cliff are red clays of Recent age, overlying
the beveled, upturned edges of the ripple-
marked Pennsylvania shales. The Triassic
is not exposed to show whether this surface
was the one on which the Triassic was
deposited or whether it was the one made
by the Pleistocene ice-sheet.
Greenhill_-Five Islands—From a point
3 miles east of Parrsboro, near Greenhill, to
Five Islands, there is an almost continuous
strip of Triassic, faulted down against the
Riversdale—Union series of Pennsylvanian
age (Fig.15). The entire region has suffered
extensive faulting and, with these move-
ments, gypsum veins have been introduced.
The Newark comprises red sandstones
and some shales, with occasional beds of
green sandstone or shale; tuff and ag-
glomerate beds; and basalt flows. The dis-
tribution of these rocks is very irregular,
owing to the faulting, and is disturbed by
extensive landslides in the volcanics.
(
u E
at r
243
PRWIZ
s Hi? ire ve
Aap Ra
ae
IS
Fic, 18.—Structure section from Moose Creek toward Blue Sack, a distance of about 2 miles, showing the character of the
On the extreme
The height of the cliffs is 150-200 feet.
right, a bed of agglomerate of the Five Islands volcanics is shown, overlying sandstone.
folding and faulting in the sediments as seen in the shore exposures.
22 SIDNEY POWERS
West of Clarke Head is an excellent exposure showing sandstones
overlain by black ash, and this by agglomerate, the whole being
cut off by a fault (Fig. 16). North of Clarke Head, agglomerate
is exposed, and copper has been sought at this locality.
East of Swan Creek, sandstone appears, overlain by a volcanic
conglomerate—a mass of fragments 6 inches to 2 feet in diameter,
of various kinds of basalt and agglomerate, imbedded in a red sand-
stone matrix. Above this, with a gradual transition, comes a true
agglomerate of angular blocks imbedded in a tuffaceous matrix
(Fig. 17). Sandstone appears above the agglomerate, and the
contact is locally cross-cutting.
At Wasson’s Bluff, agglomerate appears above red sandstone,
with a conformable contact. East of Wasson’s Bluff the agglom-
erate rests unconformably on the sandstone. Another local uncon-
formity is found at McKay Head, where the sediments are overlain
by agglomerate with columnar basalt above. East of McKay
Head are two remnants of the same basalt, with faulted contacts.
The cross-cutting nature of some of the contacts may indicate
volcanic vents.
Two Islands, known also as The Brothers, consist of basalt
flows dipping gently northwest. The islands are probably sepa-
rated from each other and from the mainland by faults.
East of Moose River the sediments reappear and extend from
this point around Minas Basin, continuously as far as the Shube-
nacadie River. The structure of the sandstones between Moose
River and Five Islands may be seen in Fig. 18. Near Blue Sack
(see Fig. 19) they are greatly slickensided, as shown in detail in
Fig. 20.
On the top of the cliffs east of Moose River, tuff, overlain by
agglomerate, forms a capping for the sandstone. ‘The thickness of
the volcanics varies, but is only too feet at a maximum. Near
Blue Sack are two beds of agglomerate interbedded with sandstone,
the lower being too feet or more, the upper 20 feet, with to feet of
intervening sandstone. One of the contacts is cross-cutting, but
there can be little doubt that the volcanics were formed contem-
poraneously with the sandstone, as blocks of basalt occur in the
latter.
THE ACADIAN TRIASSIC
swsof syodouuy [S|
CH 8S09 WWW ‘gacd a1
sabwoong soom/y 97/1)
Vit
UOIZAI SPURS] OAT 94} Jo dvyy— Or “oy
Saw S
24 SIDNEY POWERS
This strip of Triassic is bounded on the north by a fault which
probably continues east almost as far as Truro. The fault may be
seen near the town of Two Islands, and between Moose Creek
and Blue Sack the older rocks may be seen in one place at the top
of the cliffs, in contact with the Triassic volcanics.
Fic. 20.—A detailed view of the slickensides north of Long Island of the Five
Islands. The polished surfaces strike at right angles to the beach and the movement
has been horizontal. Little or no vertical displacement is shown, but the slicken-
sided surfaces strike toward the Five Islands between each of which there is a fault.
It is impossible to determine which are the major fault-planes.
Five Islands.—The Five Islands are situated west of Gerrish
Mountain. Their names, from east to west, are: Moose, Diamond,
Long, Egg, and Pinnacle islands, and Pinnacle Peak (Fig. 21).
Moose Island is nearly a mile in length and half a mile in width.
The highest point on it is 350 feet above sea-level. Diamond
Island is a small, round island, Long Island is one-quarter of a mile
long and 180 feet in height at the center. Egg Island is smaller
THE ACADIAN TRIASSIC
and round. Pinnacle Island is
a quarter of a mile long and 130
feet in height in the center.
Pinnacle Peak is merely an ero-
sion pinnacle. East of Egg
Island at ebb tide is Egg Rock.
At low tide, with a high run of
tides, the sea-bottom between
the islands and the mainland is
left dry except for numerous deep
river channels through the soft
red clay.
Moose Island consists of
basalt flows on the north, under-
lain by red sandstones on the
south. On the west end there
is a fault between red amygda-
loid and the sandstone, with a
number of gypsum veins near
the contact. On the east side
the amygdaloid and basalt above
dip north at angles of 45° above
the sandstone. At the base of
the amygdaloid is greenish-
white ash, 2 feet thick, similar
to that at Gerrish Mountain.
Fletcher's mapping of Moose
Island and of the other Islands
is largely incorrect.
Diamond Island consists of
a portion of the same basalt
flows as on Moose Island and
the other islands. The dip of
the basalt is about 40° north-
east. ;
Long Island consists of basalt
on the north and sandstone on
On the left is Gerrish Mountain.
Egg, and Pinnacle islands, and Pinnacle Peak. Complex block-faulting separates these islands.
The Five Islands are, from left to right: Moose, Diamond, Long,
Fic. 21.—The Five Islands.
iS)
ial
26 SIDNEY POWERS
the south, with the contact striking nearly east and west. The dip
of the sandstone and basalt is variable owing to minor folds, but is
in general in a northerly direction about 20°.
Egg Island and Egg Rock on the east consist wholly of red
sandstone, dipping northwestward about 15°. Pinnacle Island
consists of red sandstone on the south and basalt on the north,
dipping northwest at angles of 20°-40°._ Pinnacle Peak consists of
basalt.
Each of the islands is separated from the others by a fault,
and they are probably bounded on the north by a continuation
of the Gerrish Mountain fault. On each island the flows or sand-
stones dip northward, but at different angles.
The basalt flows of the Five Islands were undoubtedly originally
connected with the flow on Gerrish Mountain and with those on the
Two Islands. They do not, however, appear to be directly con-
nected with the agglomerate and tuff which are exposed along the
shore. Probably the dike in Gerrish Mountain was the source
of most of the igneous material, part of which flowed out, and part
of which was blown out.. The relative age of the pyroclastic
material and the flows could not be determined.
[To be continued]
AVERAGE REGIONAL SLOPE, A CRITERION FOR THE
SUBDIVISION OF OLD EROSION SURFACES"
LEOPOLD REINECKE
Geological Survey of Canada
CONTENTS
INTRODUCTION
MetuHop oF MEASURING REGIONAL SLOPES
VALUE OF THE MEASUREMENT OF REGIONAL SLOPES
a) In Determining the Agencies Which Have Formed the Surface
6) In Separating Forms Due to Different Erosion Cycles
c) In Furnishing Accurate Data for the Quantitative Measurement of
Earth Movements
Value of Certain Criteria for Peneplanation
PROPOSED SUBDIVISION
GENETIC SIGNIFICANCE OF REGIONAL SLOPES
OBJECTIONS TO THE SUBDIVISION
a) The Subdivision Is Arbitrary
b) An Accurate Average of the Regional Slopes Is Not Easily Obtained
c) It Entails Added Field and Office Work
SUMMARY
INTRODUCTION
During the four field seasons from 1908 to 1911 the writer was
engaged in topographic and geologic work in the southern part of
the Interior Plateaus of British Columbia. Certain questions
which arose in the study of the physiography of that region are
discussed in this paper.
Information regarding the physiography was acquired from a
study of the Tulameen and Beaverdell map areas at the Southern
end of the Plateaus, of the Kamloops and Shuswap? map sheets
covering 9,000 square miles to the north of them, and from the
t Published by the permission of the Director of the Geological Survey of Canada.
2 The geological work upon the Tulameen map area was done by C. Camsell,
and upon the Kamloops and Shuswap areas by G. M. Dawson of the Geological Sur-
vey of Canada. Explorations in the country between these areas have been made
by the same men.
28 LEOPOLD REINECKE
descriptions of the region lying between. The locations of the
areas in question and of the Interior Plateaus are shown on the
index map, Fig. t. No detailed work has been done to the north
of the Kamloops area, but explorations have indicated that the
000 7,
\Hudsone Hope <2
A Kamloops map area
B Shuswap 4 ”
C Tulameen «
D Sesverde// .
48 Boundary of the
| Sr eS, Plateau
128
25 Scale yoo Miles
Fic. 1.—Index map
character of the surface resembles that farther south although the
general elevation is said to be less.
The southern part of the Plateaus consists of an old erosion
surface or upland, dissected by younger deep valleys (Figs. 2, 3,
and 4). The region appears to have been overridden by a conti-
Weird Creek
East- west pra
Ferroux Me
Arlington Mt
N°2 EFast-west profile |
Wallace Mountain
N°o3 North-south profile
Nipple Mt
N2S fast-west 2
2
=
S
8
o
~
5S
Tulameen River
N°6 East-west
S
22
POS
2
es
ss00' (55
frexetairexetenes
800° Beier ey
200° ——|
3600"
3000'.
North-east profile or
VD ei
Triassic Complex JSurass,
(mainly andesite Javes and wt¥s) and &
Fic. 2.—Character
CHINA
noon
- Re
ron Raeree®
Net East. west orofive scross mnyves in the Beaverdel! me arca, Uhistentings regional and local slopes
By JOM
nook
UTTMM re
”) >
Mall Cr
Arhegtan we
East. west erotife across muyos 02 the Beavenyel! mup ares, lustratag regional slopes towards large stream valleys
Matiace Mewrtarn
Corry me
ea enathiition
ats i“ Sey
DP er
Nortihseet) profile ao the Seavervie¥ map eared, iiustnating slopes along ridges and, on Wallace Mountain, accordance
between topography and structure
King Solomon Mauntarn Curry Mountain Crystal Mountain
West form River
10 the Beaverdell map ares iHustratng variations in the elevations of interstream blocks
“
i
>
2
Fatlx Crock
3
DISS
ri Stock: focene Batholith
(pa) Po f
Oligocene and River Allawium
Post haves
Fic. 2.—Character of the surface in the Interior Plateaus of British Columbia. Horizontal scale: 1 in.=about 2? miles
AVERAGE REGIONAL SLOPE 20
‘“nental ice sheet which removed the soil covering from the upland,
carved a few shallow rock basins, and left a thin irregular blanket
of drift upon its retreat, but which does not appear to have modified
the upland slopes in any essential manner. This old upland sur-
face has all the essential characters which are commonly used as
criteria to distinguish peneplains, but the average slopes on it,
measured from the higher areas or ridges toward main drainage
lines, vary from 150 to over 300 feet to the mile, and these slopes
Fic. 3.—View of a portion of the Interior Plateaus near the Tulameen Valley
are found on the surface as a whole, not merely on isolated portions
Giiestite
If the slopes on this land form had not been measured, the
dominant discordance of topography and structure and the general
evenness of sky line would have caused it to be classed as a peneplain.
The degree of slope present, however, led to a search for indications
that would point to the fact that in this instance the stage of old
age had just begun. It was found that the drainage system upon
the upland was apparently related to a system of shear zones in the
underlying rocks, and that in some of the areas underlain by certain
Tertiary sediments and lavas, topographic form was governed by
30 LEOPOLD REINECKE
geological structure. The accordance of topography and structure
might in this case be described as a dimmed and accessory char-
acter, while the discordance was sharply defined and extensively
developed, an essential character. It was found that on an old
surface, with slopes of 3 to 6 per cent, the characters developed in
maturity were just disappearing and those related to peneplanation
were strongly developed but had not yet entirely supplanted the
others.
According to the hypothesis of the geographic cycle this land
form, if it had been left undisturbed, would have been gradually
worn down; that is, its average slopes would have been gradually
diminished, the characters of maturity have gradually disappeared,
and the characters of peneplanation have prevailed everywhere.
It seemed possible then, by using the criterion of regional slopes,
to subdivide old land forms on a quantitative basis.
The primary object of this paper is to point out the importance
of the measurement of average regional slopes upon “‘old erosion
surfaces,” and to show that such data assist materially in the more
accurate study of the physiographic development of the region in
which these surfaces occur, and of the diastrophic movements
which have taken place there. The writer believes that it will be
possible eventually to subdivide old land surfaces on the basis of
their average slopes, and has attempted to do so here. The sub-
division proposed is necessarily imperfect, partly because of the
lack of accurate data regarding the slopes of old erosion surfaces,
and largely because of the writer’s imperfect knowledge of the
literature describing such surfaces. As more data upon the slopes
of old surfaces become available, however, the imperfections of a
subdivision of this kind can be remedied.
METHOD OF MEASURING REGIONAL SLOPES
By regional slope is meant the general slope of the land toward
main drainage lines. Slope is stated here as the percentage of
vertical to horizontal distance rather than as an angle, because the
measurement of the angles of slope on a land form of moderate relief
is generally impracticable in the field, and for that reason the degree
of slope stated as an angle, especially if the angle is small, does not
31
AVERAGE REGIONAL SLOPE
JOATY UsIUEIN,T, oy} JO AoypeA oy7 Ssor9e
qsvoy}IOU SuIxOo] snvoye]q JOU] 94} JO Mor A—? ‘Ol
32 "LEOPOLD REINECKE
carry a suggestion of the actual land form to the mind of the reader.
For the measurement of such slopes either topographic maps or a
number of traverses across the region to be examined are essential.
An appreciation of the significance of the slopes can, however, be
attained only by traveling over them.
The following is an outline of the methods followed in obtaining
data from topographic maps of portions of the southern section
of the Interior Plateaus of British Columbia. These methods
were applied, in part, to the measuring of slopes upon topographic
maps of certain sections of the United States, with satisfactory
results.
The first step to be taken is the drawing of a number ot profiles,
some in the direction of the main drainage and others at right
angles to it. The profiles should include as many of the pertinent
topographic features of the region as possible. If they are plotted
with a vertical scale somewhat larger than the horizontal, they will
assist both in determining whether the land form under considera-
tion is the result of one or more cycles of erosion, in discovering
whether processes other than subaérial erosion have been respon-
sible for existent forms, and in detecting tilting or warping of the
crust subsequent to the formation of the surface. The usefulness
of profiles is discussed more fully farther on. If forms due to more
than one cycle are present, slopes should of course be measured on
each of those forms separately. In the Interior Plateaus two cycles
are represented, an older upland and younger valleys intrenched
in it. There is a distinct break or topographic unconformity
between the upland and the valley forms (Fig. 2, profiles 1 to 7).
In this instance the measurements of slopes on the older land form,
the upland, were made by taking a large number of horizontal
measurements on the topographic map from a dominant ridge line
to the bottom of a large upland valley. If a deep valley of the
younger cycle occupied the site of the bottom of the old valley, the
measurements were made to the point where the break in slope
occurred between the old and the young forms (profiles 1 and 2).
Horizontal measurements were made as long as possible, and never
less than one mile. The vertical difference was read directly from
the topographic map. Measurements were taken in both directions
AVERAGE REGIONAL SLOPE 33
- at right angles to the trend of the ridge, and also along its crest.
Variations in the slopes along ridge crests in the Beaverdell map
area of southern British Columbia are illustrated in Fig. 2, profiles
3and 4. The average slope measured on four or five ridges in this
area lay between 100 and 300 feet to the mile, and averaged over
200 feet except in places where certain Tertiary formations occurred
over which the slopes ranged between 500 and goo feet to the mile,
and averaged 600. The Tertiary areas occupied less than one-
eighth of the area of the whole upland; the average slope along
ridges therefore averaged between 200 and 300 feet to the mile.
Slopes across ridges were in this area of very nearly the same
magnitude and did not average over 300 feet to the mile.
Slopes as high as goo to 1,000 feet to the mile were found in a
few places only, and could have been omitted from the general
average without changing the result to any great extent. Such
local irregularities of slope are more likely to occur in land forms
with fairly high slopes than in those which are of a plainlike char-
acter. Of twelve measurements on the Caldwell, Kansas, map
sheet for instance, six lay between 14 and 21 feet to the mile, four
between 32 and 35 feet, one was 47 feet, and one ro feet to the mile.
VALUE OF THE MEASUREMENT OF REGIONAL SLOPES
The study and determination of the regional slopes upon old
erosion surfaces is both useful and necessary. It is useful: (@) in
helping to determine the agencies which have carved and molded
the topography to its present form, and (0) in separating forms due
to different erosion cycles. It becomes necessary (c) when an old
erosion surface is to be used as a datum for measuring diastrophic
movements. :
a) The study of regional slopes often will indicate the agencies
which have carved or assisted in carving a land form. This is
illustrated by Barrell’st work along the New England coast. He
found that certain flat-topped ridges in the interior sloped gently
toward the coast, and the plainlike surfaces, of which the ridge
tops were residuals, occurred in terraces of successively higher
tJoseph Barrell, ‘‘Piedmont Terraces of the Northern Appalachians,” Bull.
Geol. Soc. Am., XXIV, No. 4 (December, 1913), 688-90.
34 LEOPOLD REINECKE
elevations, each being separated from the next by a shorter and
steeper slope. Further study proved that a number of flat hill-
tops in this region, which have for a long time been regarded as
residuals of a tilted peneplain formed by subaérial erosion, were in
reality parts of a series of wave-cut marine terraces.
b) The measurement of slopes and’ the study of profiles were
found very useful in determining the number of cycles of erosion
through which the uplands of the Interior Plateaus of British
Columbia had passed. The older uplands and younger valley
cycles were separated with comparative ease, but detailed study of
the slopes was needed to show that no remnants of an older plain-
like surface existed within the upland itself.
c) The measurement and recording of regional slopes will be
of the greatest value, however, in cases where old surfaces and their
residuals are used to determine the manner in which earth move-
ments have taken place or the amount through which a section of
the crust has moved. The manner in which movements of the
crust have taken place sometimes can be brought out by profiles
(see Fig. 2, profile 6), but it is necessary to determine the original
internal relief and average slope of an elevated or warped old
erosion surface before such a surface can be used for quantitative
measurements of movements of the earth’s crust.
In the uplands of the Interior Plateaus, for instance, the relative
relief of points within 10 miles of each other quite commonly is
from 1,500 to 2,000 feet. If such a surface be uplifted and dis-
sected until only remnants of it remain, the difference of elevation
between them could be 1,500 feet without the section of the crust
within which they occur having been either warped or tilted. Cal-
culations of earth movements based on the assumption that such
a surface was plainlike before uplift would be liable to errors of
1,500 feet or more. If the slopes are not measured, however, old
surfaces of marked relief are likely to be thought nearly flat or of
much lower relief than actually is the case. For instance in
describing an old erosion surface in the Colorado Front Range,
Davis' says: ‘In the highland west of Palmer Lake, between
Denver and Colorado Springs the sky line seems to be essentially
tW. M. Davis, ‘‘The Colorado Front Range,” Ann. Assoc. Am. Geog., I, 42.
AVERAGE REGIONAL SLOPE 35
~ level; much more so in the actual view than would be inferred from
the crowded contours of the Platte Canyon map sheet.”
Value of certain criteria of peneplanation—The reasons for mis-
takes of the kind referred to are, first, that an uplifted old erosion
surface of moderate relief is often seen in juxtaposition to younger
topographic forms upon which the slopes are much steeper, so that
by contrast the relief on the older surface appears much less than
it really is.
A second and less obvious reason is that certain of the more
important characteristics of plainlike erosion surfaces with average
slopes of less than 10 feet to the mile are found also on old erosion
surfaces with slopes as high as 300 feet to the mile. The criteria
referred to are a general flatness of sky line and the planing of a
rather flat topographic surface across rocks of different hardness
and texture without any apparent change in the character of the
topography.
Flat sky lines: In a rolling hill country ridge lines sloping from
100 to 300 feet to the mile may appear quite flat and the complete-
ness of the illusion will depend partly on the position of the observer
and partly on the distance of the ridge line or lines from him. Flat
sky lines often are caused by the blending of more than one ridge
line of entirely different elevation in the observer’s line of sight, the
irregularities of one being neutralized by the other (Figs. 3 and 4).
The writer knows of at least one locality in the Beaverdell map area
of British Columbia where an observer, climbing up one side of the
West Fork River valley and looking across to the opposite side,
would see first a flat sky line on a ridge with an elevation of 4,000
feet, and as he climbed higher another flat ridge line would come
into view with an elevation approximately 700 feet higher and
lying 3 miles farther away. The two ridges are shown in cross-
section in Fig. 2, profile 2, the flat top of the higher, the St. John
ridge, in profile 3. Between the two positions there is doubtlessly
one where both ridge lines would blend and appear as one. The
flat sky line in this instance evidently does not mean that the
ridge tops represented in the sky line are remnants of one nearly
flat plain, for the lower one is next to a large river, the higher 3 miles
from it, and the slope between them over 200 feet to the mile.
36 LEOPOLD REINECKE
Nor can the lower and flatter of the two ridges be considered a
peneplain remnant. Both ridges are, in fact, part of one surface
in the stage of early old age, a surface with average slopes of about
23 per cent. Their nearly flat surface is doubtlessly due to their
lying between nearly parallel drainage lines.
Measurements made along apparently flat ridges, moreover,
often show that they slope at a quite appreciable rate. The slopes
upon St. John ridge, one of the ridges referred to in the preceding
paragraph (Fig. 2, profile 3), vary from 100 to 300 feet to the mile.
In Fig. 4, an apparently flat sky line is shown between the points
a and 6 which are about 73 and 6 miles respectively, from the
camera. From the photographic work done at this place it is
known that a vertical shift of ;},5 of an inch in the sky line of the
picture represents an actual fall of 90 feet in the topography, and
that between a and 0 there is a broad upland draw which is 250
feet deep, and whose sides slope at the rate of 100 feet to the mile.
If the sky line in Fig. 4 were farther away, it would, without doubt,
appear much flatter. In the clear western air, ridges 20 miles
~ away often are plainly visible.
Discordance of structure and topography: Discordance of
topography and structure must also not be considered a final proof
that the land form being examined is at all plainlike. Relatively
flat surfaces planing across the contacts of rocks of different hard-
ness are quite common in the Interior Plateaus, but sloping surfaces
which plane across the structure are much more common. The
flat areas are local developments on the rolling-hill type of Interior
Plateau topography. In one instance a flat surface was seen planing
across a centroclinal basin of relatively soft rocks which were pro-
tected on the outside by hard layers. The flat surface is shown in
Fig. 2, profile 6, just east of the point marked Hamilton Hill, and
a part of the same surface in the foreground of Fig. 4. This is
undoubtedly a case of local base-leveling and not a proof of uni-
versal peneplanation. In another locality a flat ridge top lying
next to a large river at an elevation of 3,800 feet was found planing
across the structure. The ridge, a part of King Solomon Mountain
in the Beaverdell area, is shown in cross-section in Fig. 2, profile 4,
but the change of structure is not shown in the profile. This ridge
AVERAGE REGIONAL SLOPE 37
top represents the lowest part of the upland within an area of
several hundred square miles and within 10 miles of it there are
numerous ridges from 1,000 to 2,000 feet higher. The flat surface
is a small but integral part, not of a plainlike, but a decidedly hilly,
land form. Discordance between topography and structure is,
moreover, as well developed on the sloping hillsides of that land
form as on the few flat surfaces that are present within it.
Neither approximately even sky lines, nor flat or nearly flat
areas planing across the structure, are therefore in themselves a
proof that the land form within which they occur is of more moder-
ate relief than the upland of Interior Plateaus with average slopes
as high as 6 per cent. The measurement of the slopes on old
erosion surfaces must therefore be made before one can venture
to judge of its actual relief or use it in quantitative measurements
of earth warping.
PROPOSED SUBDIVISION
The following subdivision is concerned only with the stage of
old age in the normal cycle of erosion as outlined by Davis.
An old erosion surface is for the purposes of this discussion
defined as a geographic unit worn down by subaérial processes
alone to a state of moderate relief. By geographic unit is meant |
a portion of the earth’s surface over which topographic conditions
and the underlying rock structure were essentially similar at the
beginning of the erosion cycle, and over which conditions of erosion
remained essentially the same while the cycle was in progress. It
is proposed to treat all surfaces in this stage as varying from two
types, those of plainlike forms of peneplains and forms corre-
sponding in general features to the uplands of the Interior Plateaus
of British Columbia which may be referred to as “‘beveled hills.”
Following Smith? and Davis’ peneplains are defined as geographic
units worn down by subaérial processes alone to a condition of very
moderate relief. The theory of the formation of such plainlike
land forms does not necessarily imply that all parts of them lay
tW. M. Davis, ‘The Geographic Cycle,”’ Geog. Jour., XIV (18099), 481.
2W.S. Tangier Smith, “Some Aspects of Erosion in Relation to the Theory of
the Peneplain,”’ Univ. of California Bull. Dept. of Geol., II (1899), 155-77.
3 W. M. Davis, “The Geographic Cycle,” Geog. Jour., XIV (1899), 486.
38 LEOPOLD REINECKE
near the ocean at the time of their formation. If the geographic
unit be large, parts of it must lie far from the ocean and may be at
a considerable elevation above it.‘ The ‘Almost plains”’ are char-
acterized as presenting absolute discordance between topography
and structure, graded streams and hill slopes, that is, practically
a lack of cliff and local flat surfaces, and by deep soil covering.
These are the commonly accepted criteria for determining pene-
planation. In addition, we suggest that the term be restricted
to surfaces with average slopes of less than 2 per cent, 105 feet to
the mile. For examples of peneplains one may cite the Laurentian
peneplain? of Canada, and a peneplain in the Mississippi Valley
illustrated by the Caldwell, Kansas, topographic map sheet.
The Laurentian peneplain has an area of about two million square
miles, with average slopes of about one-tenth of 1 per cent. It
differs from an ideal type in that it has been modified by the
accident of glaciation in removing the residual soil, in substituting
an irregular drift mantle, and in slightly altering the form of the
original surface. Upon the Caldwell area, average slopes vary from
10 to 50 feet to the mile, that is from one-fifth of 1 per cent to
Ze per Cent:
“Beveled hills’ are characterized as geographic units worn
down to moderate relief by subaérial processes alone. Their
‘“‘essential’”’ characters are discordance of topography and structure,
graded slopes, smooth sky lines and contours, and a deep soil cover-
ing. ‘Their ‘‘accessory”’ characters are local accordance between
topography and structure, and the local occurrence of cliff faces
and flat areas, that is, of ungraded slopes. In this instance the
terms ‘‘essential’’ and “accessory”? are used in the same way as
they are in petrography, essential characters being those which
predominate within the land form, accessory those of which but
few examples can be found and which may be entirely absent.
“‘Peneplains” and ‘‘beveled hills” are distinguished therefore
by their degree of slope and also by the occasional finding in the
«W. M. Davis, “The Colorado Front Range,” Aun. Assoc. Am. Geog., I, 42.
2 A.W. G. Wilson, “The Laurentian Peneplain,” Jour. Geol., XI (1903), 628-29.
3Henry Gannett, “Topographic Atlas of the United States. Physiographic
Types,” U.S.G.S., Folio 1, Caldwell, Kansas, sheet, 1898.
AVERAGE REGIONAL SLOPE 39
“beveled hills” type of characters which are characteristic of the
stage of maturity.
It is suggested that the upland portion of the Interior Plateaus
of British Columbia be taken as a type of the “beveled hills” form,
and that the term therefore be restricted to old erosion surfaces
upon which the average regional slopes are from 3 to 6 per cent.
The upland of the Plateaus differs from an ideal type in that gla-
ciation has removed the soil covering and substituted an irregular
mantle of drift.
The term “‘beveling’’ was introduced into physiographic litera-
ture by Tarr. He applied the term to the process of the cutting
down of certain of the peaks and ridges on a land form, by differ-
ential erosion, to approximately uniform elevations. According
to Murray’s New Dictionary one of the meanings of “‘to bevel”’ is
“to reduce (a square edge) to a more obtuse angle.”’ As used in
this paper the adjective ‘‘beveled” is meant to suggest that the
land form so designated has been reduced to one on which nearly
uniform sky lines are a common characteristic, and one upon which
ridge tops have broadened or become rounded in cross-section;
that is, the angles which ridge sides make at their crests have
been increased to obtuse angles. ‘‘Hills” are meant to suggest that
the land form is composed of numerous eminences of moderate relief
and of smooth and rounded contours. Except in so far as it sug-
gests reduction from a higher and more rugged form, the term
“beveled hills” is intended to be descriptive, and is not meant to
suggest the agencies by which reduction was effected.
GENETIC SIGNIFICANCE OF REGIONAL SLOPES
The desirability of a subdivision of this kind is that it will
stimulate the gathering of data on the slopes of old erosion sur-
faces, and that it places definite limits on the term “peneplain.”’
The value of such data and of such a restriction have been referred
to before. An added argument in its favor is that the subdivision
is based upon a factor which is of genetic significance in the develop-
ment of land forms. For the slopes of a topographic form are not
only one of the results of its development, but the amount of slope
tR.S. Tarr, “The Peneplain,” Am. Geol., XXI (January—June, 1898), 351-70.
40 LEOPOLD REINECKE
present is also a factor in the rate of its further development.
Moreover, the rate of development decreases so rapidly with
decrease of slope that ‘‘beveled hills” are probably chronologically
closer to forms in early maturity than to peneplains.
It is proposed in the following section to give proofs for the
hypothesis that the rate at which a land surface progresses through
the geographic cycle is dependent on its average regional slope, and
that its progress becomes slower as the slopes become less. ‘This
hypothesis has of course been accepted by physiographers* for a
long time, and is discussed only because of the emphasis placed
in this paper on ‘“‘average regional slope’’ and because the writer
has found no presentation of evidence to prove this hypothesis.
The products of erosion in the normal geographic cycle are
practically all removed from the land by streams. The rock waste
is moved downstream partly as débris and partly in solution, and,
if one could compare the amount of load carried by the streams on
any land form during two stages of its progress, when average slopes
were known, a measure would be furnished of comparative changes
in the rate of erosion as the geographic cycle progresses toward old
age.
The load consists of débris dragged along the stream bed, débris
carried in suspension, and rock matter carried in solution, each of
which will be considered in the order named.
A series of experiments have been made by Gilbert? on the rela-
tions between the load of débris that a stream can drag along its
bed, and its slope.
The experiments proved that the quantity of load dragged
by a stream varies in a complex manner with a set of controlling
factors—such as slope of stream bed, discharge of water per second,
fineness of débris, and form of stream channel. The changes, in
amounts carried, vary at a different rate for each of the factors con-
cerned. Under the conditions of the laboratory, the load dragged
along the stream bed varied with the slope, but at a greater rate.
tW. M. Davis, “The Peneplain,’ Am. Geol., XXIII (January-June, 1899),
R.S. Tarr, “The Peneplain,” ibid., XXI (January-June, 1898), 354, 365.
2G. K. Gilbert, ““The Transportation of Débris by Running Water,” U.S.G.S.,
Professional Paper No. 86, pp. 10-54, 120, 121.
AVERAGE REGIONAL SLOPE | 4l
If, for instance, the slope, expressed in percentage of fall to hori-
zontal distance, was doubled, the load dragged was, in the experi-
ments, increased three to more than tenfold. Conversely as the
slope decreased, the load decreased, but at a greater rate.
The load carried in suspension is partly a function of the stream’s
velocity, and depends partly upon the fineness and amount of
débris supplied. In experiments made on streams without load,
the velocity was found to vary approximately as the 0.3 power of
the slope, and the 0.25 power of the discharge."
The size of pebbles which can be carried in suspension varies as
the fifth power of the velocity; that is, if velocity were unaffected
by the addition of débris, it would vary approximately as the 3
power of the slope. Velocity is diminished by suspended matter,
but not enough to make the factor of 3 less than unity. It is prob-
able that in the majority of cases the grading of débris supplied
to a stream is such that, if the slope be increased, the maximum load
of suspended material carried by a stream will increase at a rate
comparable to the rate of increase of the size of débris carried;
that is, it will increase at a slightly greater rate than the increase
‘in slope. Conversely if the slope be decreased, the maximum load
carried in suspension will be decreased but at a greater rate than
the slopes.
If discharge and fineness of débris supplied remain the same,
therefore, both the maximum load dragged along a stream bed and
that carried in suspension decrease at a greater rate than the slope,
and the difference in the rate of decrease of the two functions
becomes greater as the slopes decrease. ‘This law of variation is
applicable to natural streams as well as to those in the laboratory.’
But changes in discharge and fineness of débris as old age pro-
gresses, both tend to reduce further the load carried. For the rain-
fall on a land form, the size of a geographic unit is likely to decrease
as the land becomes lower, and the proportion of runoff to rainfall
will also decrease so that the discharge of the streams would
decrease. The débris supplied to the streams, moreover, becomes
tIbid., 225. Discharge is defined as the number of cubic feet of water passing
a given point per second.
2 Gilbert, op. cit., p. 233.
42 LEOPOLD REINECKE
finer with old age and its increasing depth of soil. But suspended
matter added to a stream retards its velocity, and the rate of
retardation becomes greater as the débris becomes finer.‘ Hence
as the slopes became lower, both the factors of decreased discharge
and increased fineness of débris would help to a further and more
rapid rate of decrease of maximum load carried.
Obviously also the amount of creep and wash of débris down
hillsides into the stream beds is smaller on gentle than on high
slopes. The rate at which a land form is worn down by mechanical
erosion must therefore diminish very rapidly as the slopes decrease.
On the other hand, lower slopes may aid chemical erosion, in that
more rain water is absorbed and the solution of the rock materials
near the surface is increased. Chemical erosion must, however,
be a very small factor in the wearing down of a land surface, for the
matter dissolved in river waters is derived from surface rocks in the
process of weathering, and the greater bulk of the rocks at the sur-
face lose on an average less than one-third of their original weight
by the process of solution when weathering is complete. Moreover,
part or all of this loss is compensated for, both in weight and in
bulk, by gains in the form of oxygen, water, and carbon dioxide
obtained from the atmosphere, and recombined as insoluble mineral
products in the residual soil.’
If the average slopes of a land surface, therefore, be reduced in
the progress of the geographic cycle from, say, 4 per cent to 2, the
rate of reduction of the land surface by erosion will be less than
one-half what it was before, and as the slopes decrease, the process
becomes slower and slower.
The final stages of old age in which the surface is reduced to
slopes as low as one-tenth of 1 per cent must therefore represent
a very much longer period of time than the stage of maturity or of
early old age. Chronologically, therefore, ‘beveled hills” are
probably closer to land forms in early maturity than to ‘“pene-
plains,’”’ and for that reason alone the subdivision proposed in this
paper should be justified.
t Gilbert, op. cit., p. 228.
2F. W. Clarke, ““The Data of Geochemistry,” Bull. 491, U.S.G.S., pp. 462
and 465.
AVERAGE REGIONAL SLOPE 43
OBJECTIONS TO A SUBDIVISION BY AVERAGE REGIONAL SLOPES
The objections which may be urged to a subdivision of this
kind are: (a) that it is an arbitrary one; (6) that the slopes on a
land form vary widely, and two observers may come to different
conclusions regarding it; (c) that it requires a greater amount of
detailed field and office work than is necessary when the average
slopes. are not taken account of.
a) The subdivision is arbitrary, for as far as we know there is
no distinct change in the cycle at either of the two limiting points
of 2 and 3 per cent, which is placed on the two type forms proposed
here. Moreover, it is probable that there are old erosion surfaces
to represent all stages of average regional slope from 6 per cent to
less than one-tenth of 1 per cent, and there may be as many examples
lying between the two types proposed as within the limits of the
peneplain type.
A parallel might be drawn between the classification of igneous
rocks and the subdivision proposed here. In 1886 or thereabouts,
when geologists of the United States Geological Survey found large
areas in the Sierra Nevada Mountains underlain by intrusive
masses of approximately similar composition lying between the
quartz-diorite and granite families, they suggested the name
granodiorite for them. ‘Thirteen years later Lindgren’ proposed
definite limits for the “granodiorite”’ family in regard to both its
chemical and mineralogical composition. The bulk of the rock
masses referred to in the Sierras, and later found to occupy great
areas in Canada, fall within the limits proposed by him. His
quantitative restriction of the term granodiorite is therefore justi-
fied, for it represents a natural group of rocks. The term gains
stability, moreover, because of the occurrence of this group within
a definite and accessible region.
This definition of granodiorite is of great value to petrographers
because it furnishes a clear-cut standard of comparison and datum
point within the scheme of classification. The occurrence of rocks
intermediate in composition between granodiorite and granite on
the one hand, or granodiorite and quartz-diorite on the other, does
t Waldemar Lindgren, “‘Granodiorite and Other Intermediate Rocks,” Am. Jour.
Sct., IX (1900), 269-82.
44 LEOPOLD REINECKE
not detract from the usefulness of the quantitative definition of the
family, but rather adds to the necessity of such a definition. In
the same way the term ‘“‘beveled hills” proposed here represents
a land form which actually occurs over the known portion of a large
geographic unit, the Interior Plateaus of British Columbia, and the
quantitative limits proposed for the type are those measured upon
the land form in question. The value of the establishment of a
subdivision centering about a quantitatively defined physiographic
type should also not be seriously impaired by the occurrence of
numerous intermediate forms.
b) The slopes on a land form vary widely, and an accurate
average is not easily obtained. Variation in slope will cause
trouble only in old surfaces of fairly high relief, that is, in the
“beveled hills” type. In the work in the Interior Plateaus, it was
found that the greater part of the surface within areas of about
200 square miles lay between 3 and 6 per cent, and where slopes of
a mile or more in length varied greatly from the general average
they occurred over small areas. By estimating the relation of the
size of these areas to the whole, irregularities of slope were cal-
culated into the whole, and found to change the general average
very slightly. If care is taken first carefully to separate forms due
to different cycles, and then to note the frequency of the occurrence
of irregularities varying from the average, the final results will be
found to be fairly consistent.
In land of lower relief, that is, in the peneplain division, the
results will be found to agree much more closely for the variation
in slope is very much less.
c) The amount of field work is greater than is necessary when
slopes are not measured.
This is true even when the measurements are made on topo-
graphic maps, for in order to appreciate the meaning of the forms
shown on a topographic map it is necessary that one examine them
closely at first hand. The extra time and energy which physi-
ographers will of necessity have to spend in traversing old land
surfaces before they can obtain data upon the nature and extent
of their slopes is one of the best arguments for the adoption of this
classification instead of an objection to it. The geologist knows
AVERAGE REGIONAL SLOPE 45
that rocks must be cracked if results are to be obtained, and the
physiographer who depends largely upon distant views will miss
a great deal of the detail which helps to prove or disprove field
hypotheses.
SUMMARY
In the study of the physiographic development of the Interior
Plateaus of British Columbia, certain characteristics commonly
accepted as criteria for peneplanation were found well developed
upon an erosion surface with regional slopes of 3 to 6 per cent.
Stress is laid on the value of the study and measurement of the
regional slopes of old erosion surfaces, and a quantitative subdivision
of old erosion surfaces on the basis of their average regional slopes
is suggested. Regional slope is defined as the general slope of the
land toward main drainage lines, and an outline is given of the
methods of measuring regional slopes, as followed in the work on
the Interior Plateaus of British Columbia.
The determination of the regional slopes of a land form is of
value in furnishing clews to the agencies which have affected its
development, and in separating the products of the different cycles
of erosion through which it may have passed. The measurement
of regional slopes is essential if a land surface is used as a datum
for the measurement of movements of the earth’s crust. For if
such measurements are not made, an uplifted old erosion surface
is very likely to be considered of much lower relief than is actually
the case. Such an assumption leads to serious errors in estimates
of the manner and extent of movements of the crust. It is caused
partly by optical illusions, and partly from the fact that the char-
acteristic flat horizon lines and the discordance of topography and
structure which prevail over old erosion surfaces of plainlike form
are also found well developed upon surfaces of much greater relief.
It is proposed that old erosion surfaces be divided into two
central types “‘peneplains” and “beveled hills.” Peneplains are
to be characterized by average regional slopes up to 2 per cent by
discordance between topography and structure, by the absence of
local irregularities of slope, such as cliffs and flat areas, and by
deep soil covering.
46 LEOPOLD REINECKE
“‘Beveled hills” are old erosion surfaces with dominant dis-
cordance between topography and structure, with a general absence
of irregularities of slope, and with deep soil covering. In addition,
one may expect to find on them the accessory characters of partial
accordance between topography and structure and occasional cliffs
and flat areas. It is proposed that the term be confined to forms
with average regional slopes of from 3 to 6 per cent and that the
upland portion of the Interior Plateaus of British Columbia be
considered the type of this land form.
The subdivision is desirable because it will stimulate the meas-
uring of regional slopes and thus assist in working out the physio-
graphic development of the surface and diastrophic movements of
the crust after its formation. It is not contrary to the accepted
hypotheses of the genesis of a land form through the normal cycle
of erosion, for the degree of slope is a factor in the manner, as well
as the rate of development, of an erosion surface.
The objections to the subdivision are that it is arbitrary, that
a true average of the regional slopes on a land form are hard to get,
and that it involves more field and office work than are otherwise
necessary. The objections are met in the following manner.
The type form “beveled hills’’ is represented by an old erosion
surface, which is found throughout the southern portion of a large
geographic unit, the Interior Plateaus of British Columbia. The
subdivision is therefore not entirely arbitrary. The difficulty of
obtaining a true average of the regional slopes on a land surface
can be met by taking account of the relative area occupied by slopes
departing from the general average. It is thought, finally, that
the extra field work involved in traverses over the region will be
of advantage in calling attention to details of physiographic interest
which can be obtained in no other way.
It is well to repeat here that the object of this paper is first of
all to point out the importance of the study and determination of
regional slopes on old erosion surfaces, and that the particular form
of subdivision proposed is not considered final.
CAIMANOIDEA VISHERI, A NEW CROCODILIAN FROM
THE OLIGOCENE OF SOUTH DAKOTA
MAURICE G. MEHL
University of Wisconsin
In the summer of 1to11, Mr. S. S. Visher, then connected with
the Geological Survey of South Dakota, collected some interesting
crocodilian material from the Oligocene of Washington County,
South Dakota. Some time ago, the attention of the writer was
called to these remains by Dr. Visher, and recently through the
courtesy of Mr. W. H. Over, director of the museum at the Uni-
versity of South Dakota, the collection was loaned to the writer
for study.
The material herein described consists of a goodly portion of
a skull, a nearly complete mandible, two femora and other limb
bones, a nearly complete series of vertebrae, many dorsal scutes,
and numerous fragments. According to Dr. Visher, the collection
was made from the Titanothere zone of the Lower White River
beds, perhaps 20 to 30 feet above their base.
THE SKULL
Of the skull, nearly the entire right half is preserved as well
as portions from the left side including the quadrate region, the
posterior half of the cranium roof from the median line to the middle
of the orbit and supratemporal vacuity, and fragments of the
maxilla along the alveolar margin. Of the base of the skull but
little remains save the separate occipital condyle and portions of
the exoccipitals.
In general shape and appearance it is quite similar to that of
the alligators. A lateral expansion of the maxilla in the region of
the third to fifth maxillary teeth produces a marked break in the
otherwise regular outline of the muzzle, more prominent, perhaps,
than in most of the Crocodilia. The width of the skull in the
region of this maxilla expansion is 72 mm. Immediately back
47
48 MAURICE G. MEHL
Fic. 1.—Caimanoideus Visheri, dorsal view of skull, about three-fourths natural
size.
CAIMANOIDEA VISHERI, A NEW CROCODILIAN
49
of the expansion, the width is but 66 mm. The greatest width,
across the quadrates, is
approximately too mm.
The length of the skull,
along the median line from
the posterior border of the
supraoccipital to the tip, is
some 180 mm. From the
posterior edge of the quad-
rates to the tip of the muzzle
the measurement is 203 mm.
Unlike the most of the Croc-
odilia, the inter-orbital
region is flat, or essentially
so, rather than presenting
the marked concavity.
All the bones of the facial
region of the skull are sculp-
tured by more or less pro-
nounced rounded pits or
longitudinal grooves except —
the posterior ends of the
nasals. In the maxillary
region, the markings are
more or less ill defined and,
for the most part, take the
form of long and narrow
longitudinal grooves. The
pits of the posterior frontal
region are round, well de-
fined, and deep. They are
crowded close together and
separated by narrow ridges
only. The pits average
2.5 mm. in diameter, per-
haps, in this region. On the
jugals and squamosals, the
SSS
RA
Lt
—
aT
LSS
- x
Fic. 2.—Caimanoideus Visheri, right lateral view of skull and mandible, three-fourths natural size
5° MAURICE G. MEHL
pits are shallow and varying in size, for the most part minute,
but well defined.
The relations of the various bones of the skull are quite alli-
gatoroid, as are their general proportions with few exceptions.
The prefrontal is relatively longer than in the genus Alligator and
extends at least half the length of the lachrymal.in advance of the
latter element. The nasals are relatively broad, the two making
nearly half the total width of that part of the skull.
Unfortunately, part of the anterior border of the snout is miss-
ing, but the portions present are sufficient to show some of the
important characteristics. Unlike the condition in all the true
alligators, the nasals, while projecting slightly into the external
narial opening, do not form a more or less complete bony septum.
Furthermore, the premaxillae do not form an arch over the anterior
border of the opening as is the case in all modern and extinct alli-
gators with one or two exceptions, perhaps. In this respect, the
skull simulates that of Brachychampsa Montana, an alligatoroid
form described by Gilmore from the Upper Cretaceous of Montana.’
To quote: ‘In the absence of a roof-like covering formed by the
premaxillaries over the anterior part of the external nares, Brachy-
champsa differs from all known alligators, both recent and extinct.”
The anterior border of the nares in the described form differs
from that of Brachychampsa, however, in that the premaxilla in
the former are still further reduced till the nares are directed
slightly forward and lack entirely the definite ridgelike anterior
border. This is the condition pointed out by Loomis in a specimen
described by him from the Oligocene of South Dakota and referred
to the genus Crocodilus.2 Quoting Loomis on this point: “The
undivided nasal opening is very far forward, and differs from that
of the other crocodiles in the lack of a distinct anterior border, this
portion of the nasal cavity having a smooth, rimless boundary
on the premaxilla. The nostril opening would seem, therefore,
to have been directed to the front, rather than upward on the snout.
«A New Fossil Alligator from the Hell Creek Beds of Montana,” U.S. Nat.
Mus., XLI (1914), 290.
2A New River Reptile from the Titanothere Beds,” Am. Jour. Sci., CLXVIII
(1914), 420. ‘
CAIMANOIDEA VISHERI, A NEW CROCODILIAN ~° 51
(The lack of a rim gives the snout a distinctly mammalian appear-
ance.) ”’
The teeth are well preserved for the most part and, with few
exceptions, have the crowns preserved entire. On the right pre-
maxilla, there are preserved four alveolae. On the portion of the
premaxilla broken away, there is apparently space for two addi-
tional alveolae, but there is possibly only one. In the latter case,
the total number is five, the number in the specimen described by
Loomis. Concerning this series but little can be said, as only the
circular roots of four remain. Of these the next to the last is the
largest, 5.5 mm. in diameter. In each maxilla there are appar-
ently thirteen teeth, a smaller number than is usually found in the
alligators. Of these the fourth is much the largest, fully 8 mm. in
diameter at the base and approximately circular in section. The
posterior maxillary teeth are all more or less laterally compressed.
The roots are oval in cross-section and in measurements range from
2.5mm.X4 mm. to4mm.xX7 mm., the more posterior teeth being
the larger in general. The crowns of the first four maxillary teeth
are somewhat flattened on the inner side and present a slight
trenchant anterior and posterior edge. They are sharply conical
and very slightly incurved, perhaps. The crowns of the posterior
teeth show a rapid transition from this type to those with swollen
crowns, rather sharply conical in the first of the series and more
blunt or even of a rounded form posteriorly. A brief description
of the well-preserved eleventh maxillary tooth will serve well to
characterize this type. The crown is subglobular and is flattened
somewhat on the upper, inner surface. It is sharply set off from
the root by a marked necklike constriction. The apex is marked
by an indistinct, antero-posteriorly Bee carina that does not
extend down on the sides.
Of the posterior part of the shel but little remains except
the basi-occipital. The condyle is more or less spout-shaped and
is divided into two distinct surfaces by a well-marked median
groove.
The palate is almost entirely lacking except for a small portion
along the maxilla-premaxilla union. At this point there is a deep,
sharply outlined pit for the reception of the fourth mandibular
52 MAURICE G. MEHL
tooth. The pit does not perforate the facial surface of the bone,
however, as is occasionally the case in the alligators.
The lower jaws are represented by an almost perfect right
ramus and a goodly portion of the left, including the symphyseal
and articular regions. The sculpturing of the mandible is much the
same as in any of the alligators; the dentary is marked by small,
deep pits and more or less prominent longitudinal grooves. In
the region back of and below the external mandibular foramen the
surface is dotted with deep rounded pits, irregular in size but dis-
tinct. In the relation of the various mandibular elements there is
nothing of particular interest except perhaps in the unusual for-
ward extent of the splenial. This element extends far forward
and takes an ample part in the symphysis. Each ramus bears
nineteen teeth, very similar, in general, to the maxillary teeth.
The fourth tooth is the largest in the series, round in section, and
measures fully 6 mm. in diameter at the base. The crown is
largely missing, but was apparently sharply conical, and the indi-
cations are that there was a faint anterior and posterior carina
extending down the sides. This was probably the condition of the
anterior four teeth in each ramus. The root of the first tooth
indicates that it was somewhat larger (about 4 mm. in diameter)
than the two subequal teeth that follow.
Immediately following the fourth tooth is a series of seven, all
comparatively short and slender and averaging about 2 mm. in
diameter at the base and 4.5 mm. in height. These small teeth
have slightly swollen crowns and a faint suggestion of anterior and
posterior carina. The posterior eight teeth are subequal in size
and quite like the eleventh maxillary tooth described above.
The nature of the bite is alligatoroid in that the teeth of the
mandible all close within the teeth of the upper jaw and the fourth
mandibular tooth fits into a deep socket in the palate surface.
THE VERTEBRAL COLUMN
Eight of the cervical vertebrae are present, all but the atlas.
With the exception of the axis, they are all very pronounced pro-
coelous. Although the union between the centrum and the arch
is clearly distinguishable, the two parts are as a rule closely united.
CAIMANOIDEA VISHERI, A NEW CROCODILIAN 53
There is nothing distinctive in this series that serves to set them
off from the other Crocodilia save perhaps in the atlas. The
odontoid process is very prominent, and in a superficial way
resembles the spout-shaped process of some of the mammals.
The total length of the series, allowing for the missing atlas, is
approximately 18.5 cm. Of the dorsal series all are preserved.
As the cervicals, they are of the pronounced procoelous type.
The total length of the series is about 23.7 cm. The five lumbar
vertebrae are well preserved. ‘The posterior.articular faces of the
centra are all highly convex and round in outline except the fifth.
In this the posterior face of the centrum is fully twice as wide as
high. The lumbars together measure 11.7 cm. The two sacrals
measure 4.7 cm. A noteworthy feature is the shifting of the
sacral ribs. The posterior rib forms a small part of the posterior
concavity into which the first caudal fits. The anterior rib is
shifted forward to such an extent that it might be said to articulate
intercentrally, for although it is solidly fused to the first sacral
vertebra, nearly half of its diameter extends beyond the anterior
face of that vertebra and articulates broadly with the last lumbar.
Of the caudal vertebra, there are 23 preserved. There are prob-
ably about 11 missing, almost entirely from the posterior end of
the series. The vertebrae present measure about 23.7 cm. To
this should be added perhaps 16.5 cm. for those missing, making
a total of 40. 2 cm. for the caudal series.
Of the numerous appendicular bones indiscriminately pre-
served the femora alone, perhaps, deserve special mention. Both
of these bones are nearly complete, but the right is the more nearly
perfect (Fig. 3). The head is broad and much flattened. The
articular surface extends entirely around the end and on the side
of the pronounced rounded cone that rises from the concave
lower surface close to the proximal end of the bone. The tro-
chanteric ridge on the flexor surface is very pronounced, more so
than usual. At this point, about 45 mm. below the head, the shaft
is bent abruptly back and from there sweeps backward in a broad,
anteriorly concave curve to the distal end.
The dorsal armor consists of a large number of pitted plates,
sub-rectangular in outline for the most part. Of these there are
54 MAURICE G. MEHL
several distinct types and a great variation in size. All bear a
more or less prominent antero-posteriorly directed carina on the
dorsal surface and are concave below from side to side to some
extent at least and often sharply so. The dorsal surface of all is
deeply sculptured by small, rounded, closely crowded pits. While
the anterior and posterior edges are smooth, the lateral edges of
Fic. 3.—Caimanoideus Visheri, right femur; a, from below; b, from above;
c, from behind; three-fourths natural size.
most of them indicate a more or less firm union with an adjacent
plate. In some plates, this union is indicated on one margin only,
and a few apparently were entirely free. The plates were prob-
ably arranged in more or less rigid transverse rows of five units
at least, and, in much probability, seven units for certain regions of
the back. Fig. 4 indicates the apparent arrangement of the plates.
As pointed out above, the affinities of this form with the genus
Alligator are marked. This is shown chiefly in that the fourth
‘CAIMANOIDEA VISHERI, A NEW CROCODILIAN 55
-mandibular tooth fits into a deep pit in the palate instead of closing
in a notch, as in crocodiles. Furthermore, all the mandibular
teeth close within those of the upper jaw. In the lack of a division
of the anterior nares and the lateral union of the dorsal scutes, the
form is quite similar to the genus Crocodilus. It apparently stands
much nearer to Caiman, however, than to either of the genera
mentioned above inasmuch as this group
combines the alligatoroid bite, the un-
divided anterior nares, and the lateral
union of the dorsal scutes. One of the
striking differences from Caiman is to be
seen in the entire lack of the anterior
border of the external narial opening in
the form here described. A new genus,
Caimanoeda, is proposed to include this
form C. Visheri, which may be considered
the type, and C. (Crocodilus) prenasalis,
Loomis,‘ a form that a careful examination
of the type skull has shown to be very
similar to C. Visheri.
, If one may depend on the figures of
C. prenasalis there is a noticeable differ-
ence between the dorsal scutes of this
form and those of C. Visheri. In the
latter, all the scutes are more or less
strongly keeled, and are much more finely
and regularly pitted than in the former. ae, A lation between academic scholarship and
i our new search for social justice. Yet
_ these movements have an extremely in-
| timate and vital connection, which comes
“into view as we go behind the scenes and
“i carefully observe the working of the
es 1 forces that control the evolution of hu-
_ man society.”’—The Author’s Foreword.
‘ The Struggle for Justice the Funda-
a - mental Theme in the Religion of the
‘ey | Bible and the History of the Church.
P cial pasteboard; net 25 cts., postpaid 27 cts.
a | The University of Chicago Press
__ CHICAGO ce ?: ILLINOIS
Do You Want to Know
What Your Handwriting
Reveals?
WE have published a fascinating
booklet of 32 pages on the sub-
ject of graphology, by William Leslie
French. Every reader of this publi-
cation will be interested in comparing
the examples of handwriting in judg-
ing character and disposition of the
writer.
A copy of this booklet and 12 differ-
ent patterns of The’ Spencerian
Steel Pens will be sent postpaid on
receipt of ten cents.
If you can do good work with a poor pen
you can do better work with a good pen.
Silver plated Falcon pens, smooth points,
wear long, will not corrode.
SPENCERIAN PEN CO.
349 Broadway - - : New York City
3 he Astrophysical J ournal
| The forty-third volume, January to June, 1916, among other papers
Foreign pasties, 62 cents
~~ - -- —_—_-_~--—- —
_} CHICAGO
will contain important articles on
ASTROPHYSICS
On the temperature and radiation of the sun, by Felix Biske, of the
University of Warsaw; on the albedoof the planets and their satel-
lites, by Professor Henry Norris Russell, of Princeton University
The Astrophysical Journal published monthly excepting in February and August
Subscription price, $5.00
Canadian postage, 30 cents
THE UNIVERSITY OF eee aa PRESS
. ILLINOIS
FINE INKS 4D ADHESIVES |
For those who KNOW
A Simplified Typewriter
The
Remington Junior
Drawin
Drawing iabs Ink
; ; Engrossing Ink ©
~ ° 9 Taurine Mucilage __
H | x gi ns Photo Mounter Paste
Drawing Board Paste
Liquid Paste
Office Paste ;
Vegetable Glue, Etc.
Are the Finest and Best Inks and Adhesives
Emancipate yourself from the use of corrosive and ©
ill-smelling inks and adhesives and adopt the
Higgins Inks and Adhesives. They will bea
revelation to you, they are so sweet, clean, well
put up, and withal so efficient,
At Dealers Generally
Small in size—but big in capacity
Light in weight—but heavy
in stability
Remington-built Remington-guaranteed
Price $50.00
Easy payment terms can be
arranged if desired
Write for Catalogue
REMINGTON TYPEWRITER CO.
(Incorporated)
New York and Everywhere
CHAS. M. HIGGINS & CO., Mfrs.
Branches: Chicago, eceessh
271 Ninth Street Brooklyn, N.Y.
Efficient for Classroom,
Club, or Platform —
The educator or lecturer requires of a oo
wk ern accuracy, brilliancy, simplicity, and dur-
a very feeiate ea definitely characterize all models of the
Bausch’ [omb —
BALOPTICON
THE PERFECT STEREOPTICON
They have been developed from our 60 years’ experience with the intricacies of lens-making,
in connection with our unusual facilities for research in the optical field and our command
of reliable and highly skilled workmanship. For whatever use you need a lantern, there is
a model of the Balopticon which meets it exactly.
Model C—ideal for use with slides. Has the new 400-watt automatic gas-filled Mazda lamp, giving more bril-
liant illumination than the arc—with much less current. Price, complete, $35.00. New Combined Model—for
both slides and opaque an (maps, photos, postcards, etc.) with instant interchange. Its 1000-watt lamp uses
but 9 amperes. Price,
Other models from $20.00 up.
Write for our interesting illustrated circulars on Balopticons, with price lists of all models
Bausch € lomb Optical G.
554 ST. PAUL STREET ROCHESTER, N.Y.
Leading American Makers of Microscopes, Projection Apparatus, Photographic Lenses, Stereo-Prism Binoculars,
and other high-grade optical products|
a NUMBER 2
a Te “ :
tae GEOLOGY
A SEMI- tl-QUARTERLY
\
EDITED BY
THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
ORY ae ang With the Active Collaboration of VE
SAMUEL ) W. ‘WILLISTON ; Sy ALBERT JOHANNSEN
Vertebrate Paleontology ; _ Petrology
_ STUART WELLER ROLLIN T. CHAMBERLIN
- Invertebrate Paleontology ~ : soviet Peclozy,
ee te doce || ASSOCIATE EDITORS
IBALD GEIKIE, Great Britain JOSEPH P.IDDINGS, Washington, D.C,
t RLES BARROIS, France - net R : JOHN C. BRANNER, Leland Stanford Junior University
T PENCK, Germany : f _ RICHARD A. F. PENROSE, Jr., Philadelphia, Pa.
WILLIAM B. CLARK, Johns Hopkins University
j / - _. WILLIAM H. HOBBS, University of Michigan
-E GEWORTH DAVID, dasigtealiag _' FRANK D. ADAMS, McGill University
j LLIS, Leland Stanford Junior Liven, CHARLES K. LEITH, University of Wisconsin
SILBERT, Washington, D.C. .. s WALLACE W. ATWOOD, ‘Harvard University
LES D. WALCOTT, Smithsonian Tnrstitiitior ; WILLIAM H. EMMONS, University of Minnesota
| vs. _ WILLIAMS, ‘Cornell Cy, hd 2 it ARTHUR L. DAY, Carnegie Institution |
ren ve FEBRU ARY-M ARCH oe
i ah kD eS
[Ee ACADIAN TRIASSIC. PART Leas - - - - - - Sheer POWERS 105
SMIBn MACE Se imi eres
, VROPHYLLITIZATION, PINITIZATION, AND SILICIFICATION OF ROCKS AROUND
K AB abe BAY, len ea - - - - - A. F. BUDDINGTON 130
NITED. STATES. “PART BE en ge ee aetna oh teen er aan ite ge N co 153
UDIES. IN HYDROTHERMAL ALTERATION. Pre: wees - E, A. STEPHENSON 180
WEATHERING 0 OF A HORNBLENDE GABBRO
ALBERT. D. BROKAW: AND LEon Pp. SMITH. 200
= mecat -— Jaf ye se Se eh = ay = pice ES ot = x PS 206
THE UNIVERSITY OF CU ECA GO PRESS
~ CHICAGO, ILLINOIS, U.S.A.
AGENTS
, THE CAMBRIDGE UNIVERSITY PRESS, Lonpon AND EDINBURGH
HV Dac : . KARL W. HIERSEMANN, LEtpzic
& * THE MARUZEN-KABUSHIKI-KAISHA, Toxyo, Osaka, Kyoto
The Journal of Geology
Vol. XXIV CONTENTS FOR FEBRUARY-MARCH 1916
THE ACADIAN TRIASSIC. PART Il -- =) =) = = 02 (> Ss 02 = = Spey’ Powers (iam
NOTES ON RIPPLE. MARKS¢01 i=. cei penetrate a eg rene mane Rr Ce Pe TIT SPIE ae
PYROPHYLLITIZATION, PINITIZATION, AND SILICIFICATION OF ROCKS AROUND CONCEPTION BAY, —
NEWFOUNDLAND - - - - - - - - - - - Eig o 7 A. F. BuppIncTton _
THE ORIGIN OF RED BEDS. A STUDY OF THE CONDITIONS OF ORIGIN OF THE PERMO- —
CARBONIFEROUS AND TRIASSIC RED BEDS OF THE WESTERN UNITED STATES. PARTI
C. W. TomMLinson§ 15
STUDIES IN HYDROTHERMAL ALTERATION. I - aie Na <4 = mle igen E. A. STEPHENSON
ZONAL WEATHERING OF A HORNBLENDE GABBRO - - - ALBERT D. Brokaw AND LrEon P. SmuitH
REVIEWS gsi im mes aba elim rage Se aah e D ince non cei nA SE Nace MNS TESpAah Cg St NR et et cera pret a 06
The Journal of Geology is published by the University of Chicago at the University Press semi-
quarterly, on or about the following dates: February 1, March 15, May I, June 15, August 1, September 15,
November 1, December 15. {] The subscription price is $4.00 per year; the price of single copies is
65 cents. Orders for service of less than a half-year will be charged at the single-copy rate. 4] Postage is
prepaid by the publishers on all orders from the United States, Mexico, Cuba, Porto Rico, Panama Canal a
Zone, Republic of Panama, Hawaiian Islands, Philippine Islands, Guam, Samoan Islands, Shanghe ai
{| Postage is charged extra as follows: For Canada, 30 cents on annual subscriptions (total $4. 30), on”
single copies, 4 cents (total 69 cents); for all other countries in the Postal] Union, 53 cents on annual
subscriptions (total $4.53), on single copies, 11 cents (total 76 cents). {Patrons are requested to make)
all remittances payable to the University of Chicago Press in postal or express money orders or ae c
drafts. . ‘q
The following agents have been appointed and are authorized to quote the prices indicated:
For the British Empire: The Cambridge University Press, Fetter Lane, London, E.C.— ‘Yearly
subscriptions, including postage, 18s. 8¢. each; single copies, including postage, 3s. 2d. each. 3
For the continent of Europe: Karl W. Hiersemann, Konigstrasse 29, Leipzig, Germany. ‘eat
subscriptions, including postage, M. 22.65 each; single copies, including postage, M. 3.80 each.
For Japan and Korea: The Maruzen-Kabushiki-Kaisha, 11 to 16 Nihonbashi Tori Sanchea
Tokyo, Japan. Yearly subscriptions, including postage, Yen 9.00 each; single copies, including ~
*
—
postage, Yen 1.50 each. 7
Claims for missing amber’ should be made within the month following the regular month of
publication. The publishers expect to supply missing numbers free only when they have been lost in”
transit. ~~
Business correspondence should be addressed to The University of Chicago Press, Chicago, Ill.
Communications for the editors and manuscripts should be addressed to the Editors of THE
JOURNAL OF GEOLOGY, the University of Chicago, Chicago, IIl. a
Contributors are requested to write scientific and proper names with particular care and in citations —
to follow the form shown in the pages of the Journal. ¥
Separates, if desired, must be ordered in advance of publication. Separates of leading articles will be
printed as ordered, of which 50 (without covers) will be furnished graizs, the actual cost of the remainde
(and covers, if desired) to be paid for by the author. The actual cost may vary, and will depend upon
the amount of work in re-making the pages into forms, presswork, paper, binding, etc. Separates
containing half-tones may be expected to cost somewhat more, the increase depending upon the number
of cuts and the amount of work required upon them.
Entered as second-class matter, March 20, 1893, at the Post-office at Chicago, Ill., under the Act of March 3, 1879.
VOLUME XXIV NUMBER 2
THE
FOURNAL OF GEOLOGY
FEBRUARY-MARCH 1916
THE ACADIAN TRIASSIC
SIDNEY POWERS
Troy, New York
IPENRCIE JOE
Gerrish Mountain.—Gerrish Mountain consists of a basalt flow
capping Triassic sandstones (Figs. 20, 22). The sandstones on the
west side of the mountain are horizontal, those on the east side
dip northward at angles of 15° or less.
Opposite Moose Island is a cross-section of the basalt flow
(Fig. 22), showing sandstone faulted against agglomerate on the
west, with the agglomerate overlain by sandstone in one exposure;
a columnar basalt dike east of the agglomerate, and probably
separated from it by a fault; and red sandstone, east of the dike,
overlain by a 3-foot bed of ash, above which is columnar basalt.
The dike is 50 feet thick. It extends northward for some distance,
but it is cut off on the south by a fault between the mainland and
Moose Island. In either the dike, or the basalt flow, magnetite
has been mined near Lower Economy.
The final exposure of Triassic basalt on the east, which may
originally have been connected with that at Gerrish Mountain, is
at Portapique Mountain, 12 miles distant, and north of Birch Hill
(see Fig. 23).
Gerrish Mountain—Truro—tThe broad lowland underlain by
Triassic strata east of Gerrish Mountain is interrupted by a long
Vol. XXIV, No. 2 105
106 SIDNEY POWERS
strip of Carboniferous conglomerates and shales forming a high,
rugged topography from Lower to Upper Economy, as shown in
Figs. 19 and 24, rising 250 feet, or more, from the lowland on the
south. The relation of the Triassic to the older rocks, as seen
along the shore, is a fault west of Carr Brook, and an unconformity
near Lower Economy (Fig. 25).
At the fault, the Triassic consists of very calcareous sandstones,
containing conglomerate lenses and cross-bedding. Calcite has
been introduced into the sandstone, forming dark-red concretions.
The unconformity near Lower Economy shows a basal con-
glomerate composed of subangular pebbles 1 to 3 inches in length,
resting on upturned and leveled Carboniferous red shale. The
shale within a foot of the contact is weathered into a clay, but this
Fic. 22.—The shore section along Gerrish Mountain, as seen from the eastern
end of Moose Island. The Triassic sandstone, at the left, is faulted against a mass of
agglomerate overlain by a capping of sandstone. The agglomerate is probably faulted
against the dike of diabase, which has fed the basalt flow which caps the cliffs on the
right. At the base of this flow is a bed of green ash, and beneath this is normal
Triassic sandstone, with some shale.
weathering is of recent date. The basal Triassic conglomerate
pebbles consist of slate, schist, quartz, and igneous rocks from.the
Cobequid Mountains. Above the basal conglomerate, which is
25 feet thick, are interbedded sandstones and conglomerates as
seen in Fig. 26. It is 1,200 feet stratigraphically between the basal
unconformity and the Gerrish Mountain basalt flow.
From Economy to Truro, Minas Basin is fronted by a compara-
tively low land underlain by practically horizontal Triassic sand-
stones, above which, in places, are Pleistocene gravels.
The northern contact is of importance because there is a ques-
tion whether there is a fault or an unconformity. The exposures
are confined to the steam valleys, and are quite unsatisfactory.
It may be briefly stated that the relation is probably a fault as far
as Chiganois River, with another fault from there to North River,
107
THE ACADIAN TRIASSIC
worousof. sypedouuy[\\|
f/esog TH)
P.
Ko,
YNY.
Es
me
SN
| SSW L
ONAIDIT \
2,
uIseg SVUIJ[ Jo pvay oy} Jo deyy—fe ‘ory
SHIH
06845 04;
; 46 SQ
ie tas aay
Py 12¢%y
AVG GNOFGOI
SS
108 SIDNEY POWERS
as shown in Fig. 23. The evidences which favor this conclusion
are the apparently dragged dips of the Triassic in several cases;
and the lack of pebbles of adjoining older rocks in the Triassic
conglomerates near by, and the actual fault seen in Harrington
River on the west."
At Birch Hill and at Folly Village, older rocks project through
the Triassic strata according to Fletcher, who mapped both
Fic. 24.—The base of the Triassic at Minasville, showing the basal sandstones
and conglomerates resting on horizontally trunkated Carboniferous shales. The
character of the erosion surface indicates a peneplain, and the composition of the
basal conglomerate indicates a lack of residual soil on this surface at the beginning
of Triassic sedimentation.
localities with exaggeration of their size. There are reasons for
questioning the existence of older rock at Birch Hill, but the copper
prospect where these rocks are supposed to occur was not visited
in the reconnoissance.
t Certain of the localities are described by H. Fletcher, Geol. Surv. Canada, Ann.
Rept., V (1892), 142-43 P.
THE ACADIAN TRIASSIC 10g
At Folly Village, Mississippian fossiliferous limestone and
gypsum, belonging to the Windsor group, appear on the northwest
side of Debert River. The Triassic sandstones are very calcareous,
and resemble the Windsor limestones, as both are red in color.
It appears that the limestone is overlain conformably by the gypsum,
and that these Mississippian strata are overlain disconformably
by the Triassic red sandstones. With this view, the Mississippian
is confined to a small area on the northwestern side of Debert
River where fossils are readily found."
Truro—W olfville—The end of the arm of Triassic in Minas
Basin lies near Truro, and the relation of these to the older rocks
Ss D
Pe Ls T UR
Bn Ln ie Ne
Fic. 25.—Section EE. Structure section through Minas Basin near Bass River |
to show the unconformity of the Triassic on an island of Permian strata, Parrsboro
formation, just north of the Basin. SD, Cobequid group; UR, Union-Riversdale
series (Pennsylvanian); Pe, Permian. The major Cobequid fault is shown at the
south of the Cobequid group. The closely folded syncline of the Parrsboro formation
is in part overlain by Triassic sediments (7), which appear to be down-faulted on the
north.
is an unconformity, as shown in Fig. 23. This unconformity is
well exposed in Salmon River and in Victoria Park Brook (where
there is also a fault). The underlying Carboniferous strata always
show a beveled surface. This unconformity continues along the
south shore of Minas Basin, and may be seen at Minasville, on the
sides of Moose Brook (Fig. 24), at Tennycape, and at Walton.
Over this area the Triassic sandstones show nothing unusual,
except for calcitization north of Maitland.
West of Cheverie, the first exposure of Newark rocks is at
Oak Island, north of Avonport (Fig. 3). On the east side of this
island, quartz-pebble conglomerate and sandstone are exposed,
overlain by stratified Pleistocene gravels, 6 feet thick, above which
is Wisconsin till.
t This view differs from that of J. W. Dawson, Acadian Geology, 3d ed., 1878,
p. 99.
110 SIDNEY POWERS
North of Oak Island is Boot Island, which is separated from the
mainland, called Long Island, by a narrow channel, formed within
the last two centuries. North of this channel is a buried forest,
exposed at low tide. North of Boot Island, and on the north side
of Long Island, are exposures of red sandstones with occasional thin
shales in which Dr. H. M. Ami reports the presence of Estheria ovata."
Fic. 26.—Details of the Triassic sandstone and conglomerate 30 feet above the
base of the Annapolis formation, one mile east of Lower Economy.
At Wolfville the basal Triassic unconformity is exposed in a
small brook west of the buildings of Acadia College, resting hori-
zontally on upturned and beveled slates of the Meguma series.’
The basal unconformity is again exposed at Kentville, just below
the mill on Black River.
t Verbal communication.
2 The writer is indebted to Professor Ernest Haycock of Wolfville for pointing out
this locality.
3 J. W. Dawson, op. cit., p. 92; L. W. Bailey, ‘‘Geology of Southwestern Nova
Scotia,” Geol. Surv. Canada, Ann. Rept., IX (1898), 128 M.
THE ACADIAN TRIASSIC TEE
W olfville-Scots Bay.—The Wolfville sandstone outcrops on the
exposed points between Wolfville and Pereau River, the most con-
tinuous exposure being near Kingsport. ‘The sandstone contains
occasional conglomerate beds and red shales. The proportion of
shale to sandstone gradually increases toward Blomidon. The
shale in this locality is largely a red clay, with occasional green
bands, persisting horizontally throughout the exposure. The
general dip of the strata is 5-10 northward. Small faults are
numerous.
About midway between Kingsport and Pereau River, Haycock
found fragments of well-consolidated fossiliferous red shale in till,
overlying the Triassic.‘ The fossils are Estheria ovata. Dipping
under North Mountain are poorly consolidated Blomidon shales,
with the characteristic thin green beds at distances of 1o~20 feet.
The Blomidon shale continues around the hook of North
- Mountain beyond Cape Blomidon, but not as far as Amethyst
Cove. At the latter locality, basalt cliffs, partly columnar, rise
abruptly from the sea to a height of 300 to 4oo feet. These cliffs
are kept vertical by frost action on the vertical joint planes parallel
to the shore. |
Two basalt flows are visible at Amethyst Cove, dipping gently
northward, with undulating folds. The collecting place for
amethysts is in a greatly veined area about too feet below the top
of the lower flow.
Scots Bay—Bennetts Bay.—In the region around Scots Bay
there are two points of especial interest: first, the origin of the
curve in North Mountain at this point, and, secondly, the presence
of the Scots Bay formation overlying the North Mountain basalt
along the southeast side of the Bay. Furthermore, the structural
evidence furnishes a clue to the former thickness of the younger
formation.
The curve in North Mountain is formed in a syncline pitching
down to the west, and in the nose of this syncline Scots Bay has
been eroded (see Figs. 27, 28). The basalt flows of North Mountain
dip toward the Bay on all sides at angles of 3°--5°. The topographic
tE. Haycock, “Fossils in the Boulder-Clay of Kings County, Nova Scotia,”
Trans. N.S. Inst. Sci., X (1901), 376-78.
» aaa
L2 SIDNEY POWERS
slope follows the dip slope closely, beveling it slightly. At the
water’s edge there is no sea-cliff, but merely a sheet of basalt
(where exposed) sloping upward from the shore. Farther southwest
along North Mountain there are low sea-clifis, but the general
dip-slope persists to the end of Brier Island. The crest of North
SCOTS BAY
LEGENO
Sco7s Bay fermotion
TRIASSIC (L | Werrn ar. Bosalt
Fic. 27.—Map of the Scots Bay—Cape Blomidon region
Mountain is a mile or two southeast of the Bay of Fundy shore.
It is a uniformly rolling surface which bevels the tilted basalt
flows and forms a remnant of the Summit peneplain.
Around Scots Bay the top of the uppermost basalt flow is
marked by a green amygdaloidal layer in which the amygdules are
one-half to three-quarters of an inch long. This amygdaloid
THE ACADIAN TRIASSIC
outcrops on the shore from Bennetts Cove
to Ells Brook (Fig. 27). From this point
to the north shore of the Bay there are
no outcrops. Along the north shore
toward Cape Sharp, the amygdaloid has
been eroded, exposing the solid basalt
beneath. In places this basalt is colum-
nar, and in other places it contains balls,
a foot or more in length, composed of
dense basalt surrounded by amygdaloidal
rims. The balls are not sufficiently
abundant for the basalt to be called a
pillow lava.
The younger, sedimentary formation,
named for its occurrence on the south
side of Scots Bay, the Scots Bay forma-
tion, has a thickness of 25 feet. It was
discovered by Ells in 1876, and described
by him? and later by Haycock.? It con-_
sists of white, very calcareous sandstone,
quite distinct in color from any other
Triassic sandstone of Acadia, with some
interbedded shale and normal sandstone.
The Scots Bay formation outcrops in
five small synclines between Scots Bay
and Bennetts Bay (formerly called Wood-
worth Bay). These small remnants rest
conformably on the basalt, contrary to
the opinion of Haycock, and are pre-
served in small synclines in the basalt.
They extend southeast only a few hundred
feet, as the topographic slope of the
The vertical
scale from Cape Split southward is exaggerated to show the overlying Scots Bay formation which is only 25 feet thick. The level of
the Summit peneplain is shown by the line with three dots and a dash, the top of the flows of North Mountain by the finely dashed line.
The area between these two lines must have been filled with the Scots Bay formation at the time the Summit peneplain was developed.
\Wueess
any Z
=
el
ES
=a
ss
re}
REE =
WW
yal
tR. W. Ells, ‘““Notes on Recent Sedimentary
Formation on the Bay of Fundy Coast,” Trans. N.S.
Inst. Sci., VIII (1894), 416-10.
Ernest Haycock, ‘Records of Post-Triassic
Changes in Kings County, Nova Scotia,” zbid., X
(1900), 287-302.
Fic. 28.—Section DD. Geologic cross-section through Cape Sharp on the north; Cape Split, Scots Bay, and Cape Blomidon, on
the south. C, Carboniferous; 7;, Triassic, Annapolis formation; T,, North Mountain basalt; 73, Scots Bay formation.
4
(=I
OW
II4 SIDNEY POWERS
29.—Structure sections of a syncline of the Scots Bay formation, lying conformably over the top of the North
Mountain basalt.
amygdaloidal.
Fic.
Above the Scots Bay formation is till, filling the pre-Wisconsin valley. The top of the upper flow is very
The basal beds of sandstone have been replaced by chert.
mountain cuts across them
and the flows at a low angle.
These synclines are shown
in Fig. 27.
The Scots Bay formation
consists of calcareous white
or gray sandstone, frequently
replaced by chert, and green-
ish sandstone or shale. The
exposures are nowhere over
15 feet in thickness (Fig. 29)
and are remnants of a forma-
tion which once filled the
syncline of Scots Bay up to
the level of the Summit pene-
plain, as shown in Fig. 28.
The white sandstone, or
chert, rests directly on the
amygdaloid at the top of the
basalt flows, and veins of
chert run downward from the
sandstone into the amygda-
loid. The beds in any one
syncline do not matchexactly
with those in any other, but
this condition is to be ex-
pected in basal beds of which
only a few feet are shown,
on the irregular top of .a
lava flow.
Fossils have been found
in the calcareous sandstones
by Haycock. They consist
of faint green markings,
probably plant remains;
worm burrows; fish scales,
bones, coprolites, and other
THE ACADIAN TRIASSIC II5
fragments of fish. The coprolites are from 1 to 13 inches in length,
an inch wide, and half an inch thick. In 1913, Haycock found a
portion of the head of a fish which has been identified by Mr. L.M.
Lambe as the Triassic genus, Semionotus fulius (Agassiz).
Digby Gut.—Between Kentville and Digby Gut there are few
outcrops of the Annapolis formation and no cross-sections of the
North Mountain basalt. The best cross-section of the latter is at
YS
(news me casait
Gulliver’s Cgve Ss . TRIASSIC. [\Neniden stale :
i SS \' QQ efile sandstone
KS
Sms les
Fic. 30.—Map of the Digby-Rossway region
Victoria Beach, on the east side of Digby Gut (Fig. 30). The
exposures on the west side of the Gut are disturbed by faulting.
The section of North Mountain basalt, except the lower flow,
which appears at the side of Digby Gut, commences on the Bay
of Fundy shore, where 7 flows may be seen (see Fig. 31), each hav-
ing a thickness ranging from 2 to 45 feet. All the flows dip toward
the Bay of Fundy at a low angle, as seen in Fig. 32, but this uniform
slope is in places interrupted by minor folds. The presence of a
low syncline and the lack of exposures make the exact thickness of
the lower flow uncertain, but it is probably about 600 feet.
116 SIDNEY POWERS
Faults occur at right angles to the axis of North Mountain, at
Digby Gut and at Bay View (Fig. 33). The physiographic evidence
of these faults is seen in the offset of the North Mountain basalt,
and in the valleys along the fault-lines.
On the shore of Annapolis Basin near Port Wade, and at Digby,
there are exposures of slightly cemented sand, containing blocks
Fic. 31.—Five lava flows of North Mountain at Digby Gut, as seen north of
Victoria Beach, on the northeast side of the Gut. The upper flow is the third from
the top of the series as exposed.
of basalt, which were considered by Bailey to be of Triassic age,
and to underlie the basalt flows of North Mountain.’
These beds are of post-Wisconsin age, because of (1) the lack
of consolidation, except very locally; (2) the yellow color, lke
ordinary stream gravels (unlike any Triassic deposit except the
“Lae Bailey, ‘Triassic (?) Rocks of Digby Basin,” Trans. N.S. Inst. Sct., IX
(1898), 356-60; also ‘Geology of Southwestern Nova Scotia,” Geol. Surv. Canada,
IX (1898), 126 M.
“uIeJUNOJ, YIION Jo
apis YINos ay} uo yuoWIdIvdsa ay} sdNpoid 0} Yorq posoy}voM Uosaq SLY YOTYA opvYS pot SI 9pyspury sty} Jo YSII sy} 07 pue Mopog
*(saysep Aq uMOYs sv) a1njoId dy} Jo 10799 dy} Iv9U UTeJUNOU oY} UO 9plspue] oy} YYeoueq ysnfl st SMOG oYyI Jo aseq sy, “Io WUIoI]x9
ay} 4 odojs-dip oy} ut Uses of8ue oy} Ayo}eUNLxoIdde ye YJI0U dy} 07 SuIddip smoy zeSeq Jo S}SISUOD UTe}JUNOT YON ‘aroys aytsoddo
dY} UO US ST YOVIG VIIOJTA JO WBRT[IA oy, “ND AQSIC JO opIs }Svoy}AOU 9Y} UO UTLJUNOJY YON YSnory} uorjoos oy[—ze “Oly
TL]
THE ACADIAN TRIASSIC
118 SIDNEY POWERS
Quaco conglomerate); (3) the lithological character and the
lack of green laminae; (4) the delta character of the deposit
at Digby; (5) the basalt fragments decreasing in number with
increasing distance from the talus of North Mountain basalt;
(6) the horizontality of the stratification (the red and green
Triassic shales near Victoria Beach dip northward at an
angle of 3°).
Rossway—Brier Island—At Rossway on St. Mary’s Bay (Fig.
30), there are excellent exposures of red shale, with occasional green
beds and red sandstone beds, comprising the Blomidon shale.
Rossway and Gulliver’s Cove are connected by a valley which
marks a north-south fault similar to that at Bay View. The dis-
placement of the fault may be seen at Gulliver’s Cove, in columnar
basalt. No thin flows are shown here, or along Digby Neck to
Brier Island.
The Blomidon shales at Rossway have a thickness of about
500 feet. They dip northward at angles up to 10°. No other
shales in the Acadian Triassic are as well consolidated. Ripple
marks, current undulations, cross-bedding, and rarely mud cracks
are seen in the shales.
On the shore of Digby Neck, west of Rossway, the shales are
exposed for a mile, dipping under the basalt. Half a mile west of
the first exposure are Pleistocene clays containing black lignite
and basalt fragments. This clay may have been deposited in the
post-Wisconsin submergence.
Digby Neck, Long and Brier islands show in common a depres-
sion in the center of the ridge, parallel to the strike of the lava
flows. This depression marks the amygdaloid at the top of the
lower flow, as portions of but two flows are shown above the sea.
No sedimentary rocks are shown on the St. Mary’s Bay side west
of the exposure near Rossway.*
Cross-faults are shown between Digby Neck and Long Island,
and between Long Island and Brier Island. Another fault prob-
ably occurs between Brier Island and the submerged ledge on the
: A. Gesner described red sandstone exposed off Brier Island at low tide, but, he
probably mistook either the red seaweed or a hematite stain over basalt for sandstone
(Remarks on the Geology and Mineralogy of Nova Scotia, Halifax, 1836).
11g
THE ACADIAN TRIASSIC
"JSIMYINOS VY} UO SI S}[NVJ-SSOID 9Y} JO MOIYJUMOP 9Y} asNed0q ‘IJo] VY} UO UILJUNO YON Jo Jopureuros
oy} ueyy AqsIq Jorvou ATIATWLIAI SpULIS SMOIIY BY} UIIMJOq YO] oy J, ‘“oUul]-}][Ney TepWMIs ve UO powI0J ATqeqoid sem yoryM “ny AqSIC,
0} sjutod }yS11 oy} UO MOIIY OY, “}NeF MotA AVG oY} SYTeW YOIYA Yoou ay} 0} szutod yo] oy} UO MoIIe oyy, ‘“Urefdousd yruMUNS
oY} SyIew “souIsIp oY} Ul “UIeJUNOPT YWON jo do} oy, ‘“urejUNOy YANO Jo Joo; oy} WoIy AqSIq pur yng AqsIq— Ef! “914
120 SIDNEY POWERS
west. Beyond this ledge there is no evidence of the existence of
any Triassic rocks.
AGE
The age of the Newark group must be determined by a compari-
son of its fauna and flora with that of Europe where the Triassic
system is well developed. As forms common to both countries
are not abundant, there are slight differences of opinion as to the
exact correlation. Table I gives a correlation scheme which is
modified from one given by Eastman."
Trias Great Britain Germany Eastern U.S.
Rhaetic Rhaetic
Keuper marl Upper
Upper Keuper marl Middle + Keuper
(Upper Keuper sandstone) | Lower
————._$ANN |__| Newark group
Lettenkohle
Middle | Lower Keuper sandstone
Upper
Middle + Muschelkalk
| tower
Upper variegated sandstone
Lower Pebble beds
Bunter sandstone Buntersandstein
On the evidence of the fish fauna Eastman? concludes that
the Newark is to be correlated with middle and upper divisions
of the Alpine Trias (the Upper Muschelkalk—Middle Keuper of
the German section). The plants indicate a similar age, and several
forms have been cited as the equivalent of the Lettenkohle forms
of Germany.
In the Acadian area the fossils which have been found are:
plant remains at Split Rock (Gardner’s Creek), Quaco, and
Martin Head, New Brunswick; fish remains in the Scots Bay
formation at Scots Bay; and impressions of the shells of bivalved
crustaceans in drift material from the Blomidon shale, found near
Kingsport.
«C. R. Eastman, ‘‘Triassic Fishes of Connecticut,” Conn. Geol. and Nat. Hist.
Surv., Bull. 18, t911, p. 26.
2 [bid., p. 29.
THE ACADIAN TRIASSIC IZ
The plant remains were described by Dawson’ from poorly
_ preserved material as Dadoxylon Edvardianum. ‘They consist
of silicified plant-stems and of lignite, showing pith-casts. At
Gardner’s Creek and at Vaughan Creek (Quaco), the material is
largely silicified, and appears to have been transported some
distance. At Martin Head, lignite is exposed in several horizons
and is quite abundant. Silicification has not replaced the plant
tissues to such an extent as in the other localities.
The Martin Head locality is the only one where material is
available for study. Miss Holden has recently examined the
lignite, and found two species of plants.*, The form which was
assigned by Dawson to the genus Dadoxylon has been found to be
identical with Voltzia coburgensis Schaur., from the Lettenkohle
and Lower Keuper of Germany. The other form is Equisetum
rogersii, Schimper, which has been described by Fontaine from
the Virginia Triassic.
The correlation of these forms is also considered by Miss
Holden. The Voltzia is apparently the same as the form described
by Newberry as Palissya from the New Jersey area,* and as the
form Cheirolepis from New Jersey and Virginia. The Equisetum
rogersit is probably identical with E. columnaris, described by
Bronn, from the Lettenkohle.
Fragmentary fish remains have been found by Haycock$ at
Scots Bay in the calcareous sandstones overlying the basalt.
Recently further collections have been made by Professor
Haycock and the material has been identified by Mr. L. M.
Lambe, of the Geological Survey of Canada, as probably Semzo-
notus fultus (Agassiz), a form common to the other Newark
areas.
tJ. W. Dawson, Acadian Geology, 3d ed., 1878, p. 108; also, Notes and Addenda,
Pp. 99-
2 Ruth Holden, “‘Fossil Plants from Eastern Canada,” Annals of Botany, XXVII
(r913), 248-54.
3 W. M. Fontaine, U.S. Geol. Surv., Mono. 6, 1883.
4J.S. Newberry, U.S. Geol. Surv., Mono. 14, 1888.
5 E. Haycock, ‘‘ Records of Post-Triassic Changes in Kings County, Nova Scotia,”
Trans. N.S. Inst. Sct., X (1900), 287-302.
122 SIDNEY POWERS
In fragments of shale found in the drift near Kentville, by
Haycock, are impressions of Estheria of two slightly different types,
both of which must be provisionally called E. ovata. The shale
fragments were evidently derived from the Blomidon shale, and
they are very similar to some of the hard barren shale exposed at
Rossway.
The paleontological and paleobotanical evidence proves that
the Acadian area is a part of the Newark system, and further shows |
a pronounced similarity between the Newark and the Lettenkohle
of Germany.
[To be continued|
NOTES ON RIPPLE MARKS
J. A. UDDEN
University of Texas, Austin, Texas
In a paper on ripple marks, recently published in the Journal
of Geology, by Dr. E. M. Kindle, the opinion is expressed that the
size of ripple marks may bear some relation to the depth of the
water in which they were formed. Entertaining the same idea,
I have on various occasions taken notes on the size of ripple marks.
That most ripple marks vary in size with depth of the water seems
to me hardly to admit of a doubt. Ripple marks from 3 to 4
inches in width appear to be most common. They are often to be
seen in thoroughly sorted beach sands of all ages, from the Cam-
brian up to the Pleistocene:
In the Lower Comanchean, in Pecos County, in Texas, I have
found some ripple marks of very small size, the smallest I have
seen, with one exception. ‘These were noted at several points in
some thin-bedded layers of sandstone of fine texture. These sandy
layers are interbedded with clays and limestones. A piece of this
ripple-bedded rock is shown in Fig. 1, in natural size. Twelve
ripples measure together 3 inches across, making an average of
one-fourth inch for each ripple, from crest to crest. The depth
of the troughs measures about one twenty-fifth of an inch. These
ripple marks are symmetrical. A rough mechanical analysis of
the sand in this rock is as follows:
Diameter of Grains Percentages
in Millimeters by Weight
fh Sea) is a ae Aa eas Gen ts REE 80
sty/ aN Oty le thas 8 artes) apeen nlc tr Ae OAR er Fg MR CR 20
Two years ago I found ripple marks of the same size, or possibly
slightly smaller, forming in some fine sandy silt in the Rio Grande,
in Webb County. The silt had been washed up on some large
blocks of sandstone, which were strewn in the channel of the river.
It lay in shallow depressions on these rocks, and the water covered
123
124 IA. TD DEN
the ripple marks from a half to one inch deep. The wind stirred
the surface of the water gently into small waves, and the ripple
marks in the sand were seen to be building, under the influence
of these waves.
Fig. 2 shows some ripple marks in a fine silty sand of the marine
Jurassic, near Minnekahta, South Dakota. They measure 13 inches
from crest to crest and have an average depth of fifteen-hundredths
Fic. 1.—Ripple marks in Comanchean sandstone, from Pecos County, Texas.
Natural size.
of an inch. These ripple marks are unsymmetrical, their longer
slopes bearing the average ratio of 152 to 100, to the shorter slopes.
A mechanical analysis of the sand in this rock was found to be,
roughly, as follows:
Diameter of Grains Percentages
in Millimeters by Weight
F/O PTAA esa ore a ee Ae Oke ae ee Trace
L/h pe 20 Bia tte cas tik ee a ee eee a A eee 55
1/8! SU TOn eae Seah ie ee OL eee 30
Tif NOS) SO ek teenth ce cde Stan Fea eas ere Roe RR I 15
Some large-sized ripple marks occur in the Ordovician dolomites
at Utica, in Illinois. In the old entries where cement rock long ago
NOTES ON RIPPLE MARKS 125
was mined for the Utica Cement Works, some ripples have been
disclosed that measure from 4 to 5 feet across from crest to crest.
This is in a somewhat thin-bedded dolomite, which contains some
sand. Evidently this limestone was not a shallow-water deposit.
The ripple-bedded layers lie some 100 feet below the base of the
St. Peter sandstone. .
The widest ripple marks that have come under my observation
are in a crinoide! limestone in the lower part of the Burlington,
Fic. 2.—Ripple marks on Jurassic sandstone, near Minnekahta, South Dakota.
One-half natural size.
in the southeast part of Louisa County, in Iowa. These ripples
measure nearly 6 feet from crest to crest, and are at least 6 inches
deep. ‘The presence of crinoidal remains in this rock, which con-
tains some shaly material, indicates, if not proves, deep-water
conditions. How deep?
Higher up in the geological column I have seen some quite
large ripple marks in the Comanchean, in Texas, in a horizon near
the Kiamitia clay. About 17 miles west-southwest from Kerrville
such ripple marks occur in the bed of Guadalupe River (see Fig. 3).
They measure about 14 inches across and are about 13 inches deep.
They are slightly unsymmetrical. The rock in this case is a mixture
of calcareous and shaly material, which contains variable quantities
of fine sand, so that some layers might more properly be called
126 J. A. UDDEN
sandstone. The same horizon is exposed in the bottom of Bosque
River, at Clifton, 155 miles northeast from the locality just men-
tioned, and again some 6 miles north of Clifton in the same beds in
the same stream. Some layers of limestone here show ripple
marks that measure 4 feet across, near Clifton (see Fig. 4), and from
2 to 3 feet across at the northernmost locality (Fig. 5). The lime-
Fic. 3.—Ripple marks in thin-bedded sandy limestone in the bottom of Guada-
lupe River, about 17 miles southwest of Kerrville, Texas.
stone layers here are compact and quite pure in composition, but
are interbedded with marly shales.
Perhaps it may be permitted to submit some general remarks
anent the phenomena of ripple marks. They shall be brief. Ripple
marks must be due to rhythmic variations in currents in the medium
of sedimentation. They are in this respect kin to wavelike etchings,
known to be caused by rhythmic movements of corrading currents.
Perfectly symmetric ripple marks are probably the result of to-and-
fro movements of equal extent in both directions, when these move-
ments are such that the velocity of the motion happens to be
NOTES ON RIPPLE MARKS E277
sufficiently strong to move material of the coarseness present where
the rhythmic motion prevails.
On the bottom of any billowy water, sufficiently shallow for the
size of the waves, there must be a to-and-fro motion for each passing
wave. For waves of the same size, the deeper the water the more
slow and the more limited will this motion be. Hence the less will
Fic. 4.—Ripple marks in Comanchean limestone in the right bank of Bosque
River, near Clifton, Texas.
be the diameter of the particles it will be able to stir. There must
be a certain depth where the motion will be just speedy enough
to stir particles of silt. Where the bottom lies at this depth, and
where it is covered with silt, ripple marks will form. Should not
their width be determined by the extent of the to-and-fro move-
ment in each direction? ‘This decreases downward according to a
known law.
It is evident that the velocity of each to-and-fro movement on
the bottom of an agitated body of water begins with zero, rises to a
128 J. A. UDDEN
momentary maximum, and falls again to zero. For particles of
different sizes, there must be different times of duration of speeds
attaining and exceeding the respective limits effective for their
transportation. This time, and hence the latitude of this effective
translatory motion, will increase with the fineness of the stirred
sediment. With waves of one and the same size, and with the
Fic. 5—Ripple marks in Comanchean limestone in the bed of Bosque River,
about 6 miles north of Clifton, Texas.
same depth of water, the width of ripple marks should be greater
in fine sediments than in coarse. The currents producing them
will carry fine elements farther than coarse. With waves of the
same size ripple-mark building in sand should then also take
place in somewhat more shallow water than ripple-mark building
in silt.
Some ripple marks must be produced by a wavelike or rhythmic
motion which results from a reaction by the transported material
on translatory bottom currents in water and in the air. No surface
NOTES ON RIPPLE MARKS 129
billows in the atmosphere can have anything to do with ripple
marks in dune sands. Do dune-sand ripple marks vary in size
with wind velocity and coarseness of the sand? They do not
vary very much. May ripple marks be formed by a like reaction
with bottom currents in deep water? If so, their variation in size
may also be small. Such ripple marks, like those in sand dunes,
should always be unsymmetrical. Their sizes are probably
independent of depth of the water.
PYROPHYLLITIZATION, PINITIZATION, AND SILICIFI-
CATION OF ROCKS AROUND CONCEPTION BAY,
NEWFOUNDLAND
A. F. BUDDINGTON
Princeton University
INTRODUCTION
This paper embodies the results of a study of the regional and
local alterations which have affected a series of volcanic rocks
lying around the borders of the head of Conception Bay, on the
Avalon Peninsula of Newfoundland. The field work was accom-
plished by the writer as a member of the Princeton Geological
Expedition in Newfoundland during the summers of 1913 and 1914,
in connection with a general study of the pre-Cambrian rocks of
this region. The writer is indebted to the Geology Department
of Princeton University for facilities for studying these rocks in the
field and laboratory; to Dr. C. H. Smyth for supervision in the
preparation of the report; to Professor G. Van Ingen for the
photographs with which this paper is illustrated and for his interest
in the work. The numbers used in this report refer to specimens
deposited in the museum of Princeton University.
LOCATION
Regional alterations, such as silicification and chloritization,
have affected the volcanic series wherever they outcrop, either in
the area here under consideration (Fig. 1), or at other points to the
north, such as Clarenville on Trinity Bay or Goose Arm on Bona-
vista Bay. The local alterations, comprising pyrophyllitization
and pinitization, have affected the volcanics only in limited areas;
the former being exhibited in a long narrow strip of rocks south
of Manuels and the latter in outcrops to the north of the mon-
zonite stock at Woodfords and in minute amounts associated with
the pyrophyllite rocks at Manuels.
130
HYDRON SILICATES IN ROCKS OF CONCEPTION BAY 131
STRUCTURE
The volcanic series forms the lowest member of the Algonkian
rocks in this region and has been mapped as Huronian by Howley
(1907). The volcanics at the head of Conception Bay outcrop on
CONCEPTION. BAY.
Nn
*Feip ssi."
Gre, GY
Ste,
"
-228F2
“
+
=
Ye,
4 Tale 2
he228r5
1
2 a a “
“4
.
. 4 “
eee
aos
Sketch Map of Geology at
the head of Conception Bay
Newfoundland
Tepagraphy Based en Admiral Cros! No 236
By AF Buddinglan iss
Legend
GlCambrian Shales & limestones
Mone onile
Ga Protas
(cman |
—— Railroad
Avondale Veianics
wee Aerial Tram
Tale Pyrophyliile) Prospect
Pa y
Fic. 1.
the core of a major anticline, the eastern limb of which has been
intruded by a huge batholith of granite. On the west side of Holy-
rood Bay they are also intruded by a stock of monzonite. : The
rocks are in addition excessively disturbed by profound and
intensive faulting, and usually dip steeply.
There is a strong probability that the line of contact between
the granite and volcanics at Manuels marks the approximate locus
132 A. F. BUDDINGTON
ofa fault zone. For at talc prospects 3, 4, and 5 the volcanics are
faulted against either granite or green slate beds, and at prospect
3 the granite adjacent to the fault plane is silicified and pyritized
and the rhyolite is silicified and carries traces of pyrophyllite.
The pyrophyllite veins in turn are offset by small cross-faults.
CHARACTER OF VOLCANIC SERIES
The volcanics comprise a thick series of rhyolite and basalt
flows with corresponding interbedded breccias, crystal tuffs, and
tufis, and a minor amount of waterworn material. The evidence
with respect to their origin all points to their having accumulated
under subaerial conditions.
TOPOGRAPHY
The topography developed on the volcanics at Manuels is that
of a long, narrow, more or less barren plateau about 600 feet above
sea-level. The volcanics at the head of Conception Bay are carved
into a series of rugged isolated hills or ridges with differential eleva-
tions of from 200 to 1,000 feet. Glaciation during the Pleistocene
period had a marked effect on the superficial features of the country,
and many of the outcrops were scraped and polished by this agency.
WALL ROCKS OF THE PYROPHYLLITE VEINS
The pyrophyllite is confined almost exclusively to the rhyolite
flows. Occasionally, however, pockets are found in the rhyolite
breccias and conglomerates, but none at all occurs in any of the
other rocks. The rhyolite flows exhibit three characteristic struc-
tures: flow or banded, spherulitic, and elliptical or lenticular.
The spherulites may range in size from micro-spherulites visible
only with the high powers of the microscope to huge spheroids as
big as a man’s head or even larger. They are usually more or less
replaced by quartz of chalcedony. The elliptical structure has
been called such because of its appearance on the weathered surface
of the rock, where it shows as an assemblage of rude ellipses, or
as lenses surrounded by a more or less schistose material which
may be pyrophyllitized (Fig. 2). The ellipses vary from several
inches to a foot in the direction of their longest axis. At talc
prospect 5 a rhyolite showing this structure also contains scattered
HYDRON SILICATES IN ROCKS OF CONCEPTION BAY 133
spherulites. This structure is characteristic of the white rhyolites
of this area and may owe its origin to primary flowage phenomena,
or to secondary dynamic forces, or probably to the former
accentuated by the latter.
DESCRIPTION OF PYROPHYLLITE
The pyrophyllite veins are of such an extent that they attracted
attention as a source of talc; many prospects were opened in the
Fic. 2.—Lenticular structure in rhyolite. The material surrounding the more
massive portions is partially pyrophyllitized.
deposits and a 24-mile aerial tram was built to the nearest mine.
But, owing probably to the difficulty in separating the pyrophyllite
from the admixed quartzose nodules, all work has been abandoned
since 1904. ,
The pyrophyllite where it replaces rhyolite flows, as it does
almost exclusively, is a soft cryptocrystalline, light greenish-yellow
rock with a waxy luster and a good cleavage parallel to the schis-
tosity. In one case where it replaces the matrix of a volcanic
conglomerate it is a light brown and in another where it replaces
the matrix of a volcanic breccia it is cream colored.
134 A. F. BUDDINGTON
The pyrophyllite may occur either as single well-defined veins,
or as a series of veins, pockets, and lenticels, which together con-
stitute what may be called a pyrophyllitic zone.
The former character is illustrated at talc prospect 5, where the
pyrophyllite forms a vein about 500 feet long and varying from 6
to 15 feet in width in a white, densely spherulitic rhyolite. Near
the one end of the vein which is exposed the pyrophyllite is full
of nodules and stringers of the rhyolite, but becomes almost clear
pyrophyllite in its central portion.
The latter character (pyrophyllitic zone) may be illustrated by
the character of the pyrophyllite deposits at talc prospects 1 and 2.
The country rock of the pyrophyllitic zones may be so altered as
to constitute a quartz-pyrophyllite schist consisting of micro-
crystalline quartz and pyrophyllite, as at talc prospect 1, or it may
be partially pyrophyllitized, as at talc prospect 2, or relatively
unaltered as at talc prospect 4.
At talc prospect 1 large masses of pyrophyllite occur in pockets
from 1 to 15 feet in diameter containing more or less country rock,
or as thin sheets incasing lenses of quartz-pyrophyllite rock oriented
parallel to the cleavage. It frequently occurs as an interlacing
network of films veneering lenses of the quartz-pyrophyllite rock
or as lenticels replacing the matrix between adjacent quartzose
nodules. The pyrophyllite (222 E 2 f x) usually serves simply
as a matrix for these nodules varying from a fraction of an inch to
several feet in diameter, and even hand specimens are infrequent
which do not contain one or more of them. Ramifying stringers
of country rock may wander aimlessly through the pyrophyllite
(Fig. 3) and veins of pyrophyllite reticulate in the country rock.
It is quite possible that the nodular structure originated through
the total replacement by pyrophyllite of the sheared zones between
lenses of a rhyolite like that shown in Fig. 2, and the alteration
of the lenses themselves to a quartz-pyrophyllite rock. On the
west side of the talc mine here small pockets of cream-colored
pyrophyllite, weathering green or yellow, are found replacing the
matrix of a very coarse rhyolite breccia.
At talc prospect 2 there is a pyrophyllite zone about 30 feet
wide in which pyrophyllite constitutes from a small percentage
HYDRON SILICATES IN ROCKS OF CONCEPTION BAY 135
to one-half of the rock. Paralleling this zone at a distance of about
20 feet is a pyrophyllite vein 18 feet in width with a 3-foot stringer
and many spheroids of altered rhyolite wall rock in its central
portion. The spheroids vary from an inch to a foot in diameter, but
average about 4 inches. A lenticular or elliptical structure (Fig. 2)
characterizes the rhyolite adjacent to the vein and the schistose
matrix of the lenses or ellipsoids is partially pyrophyllitized. A
few hundred feet north of here a light brownish pyrophyllite is
Fic. 3.—View of portion of pyrophyllite vein, showing intermingling of pyrophyl-
lite and country rock. =pyrophyllite; g¢=quartz-pyrophyllite.
found replacing portions of the matrix of a white rhyolite con-
glomerate.
DESCRIPTION OF PINITE
At Manuels the pinite is a relatively rare constituent and is
interesting only from the viewpoint of its origin. It is best
exhibited at talc prospect 5 and at a point marked 228 D 1 on the
map. Fig. 4 is a photograph taken at this latter locality and repre-
sents the matrix of a spherulitic rhyolite (228 D 1 h) replaced by
dark-colored pinite. The spherulites here average about 1 inch
136 A. F. BUDDINGTON
in diameter and are so intermingled with smaller ones as to make
up almost the entire bulk of the rock. The pinitized groundmass
possesses a waxy luster, dark dirty-green in color, and is quite soft.
The parting of the pinite is in general parallel to the cleavage of
the rhyolite, although in detail it is a series of curving shell-like
scales, owing to its parting following the circumference of the more
resistant spherulites. An analysis of this matrix is given in this
Fic. 4.—Pinite (p), replacing portions of the matrix of a spherulitic rhyolite
Journal on p. 137 (No. 7). Very rarely pinite is found along the
original contraction cracks of the spherulites or at the heart of
a spherulite. Patches, lenticels, and minute veins of pinite are
found throughout the rhyolite flows and agglomerates, often repla-
cing the matrix of spherulitic zones (228 G 1 k) or certain flow lines
(222 BE 2%).
In the valley of Harbour Main Brook, among a series of rhyolite
flows and tuffs, tuff beds up to 75 feet thick have been partially
altered to pinite, and spherulitic rhyolite flows up to 30 feet thick
are streaked and banded with pinite. These rocks have been
/
HYDRON SILICATES IN ROCKS OF CONCEPTION BAY 137
prospected to depths of 15 and 20 feet, probably under the
misapprehension that they carried pyrophyllite. A chemical
analysis of the pinitized groundmass of the spherulitic rhyolite is
given on p. 137 (No. 8).
CHEMICAL ANALYSES
Chemical analyses of eight typical rocks showing the various
types and some of the stages of the alterations and replacements
which have affected the volcanics are here given. These analyses
were recalculated to correspond approximately to the mineral
composition of the rocks. Small amounts of water of absorption,
iron oxides except in No. 7, excess alumina, etc., have been lumped
together as such under ‘other constituents.”’ This involves of
course a slight but inappreciable error in the proportions of the
other minerals. It is probable that some sericite is also present
in rocks Nos. 3 and 4, but owing to the difficulty of distinguishing
sericite from pyrophyllite under the microscope, and because
of the fact that the decrease in potash with an increase in water
TABLE I
SHOWING CHARACTER OF ALTERATIONS OF RHYOLITE
I 2 3 4 5 6 7 8
SIO ree sto: 76.24 | 80.60 | 74.51 | 72.10 | 65.04 | 88.09 | 54.47 | 61.07
AUG O ese nce 22 Ss USE OF | ln 7 ek fl2) e240 51/1 20.4G) © 19253) |) 27. LAs" 22.00
GOs Sea aeoees 0.89 | 0.89 T.28 | 0.54! 0.28 | 0.20 2.58 1.56
EO Ras. 0.13 | 0.08]. 0.08] n.d. n.d. n.d | 0.47 |) 0.42
IMIG OP.) OsDy OFS Ll OnO4 AMON OA MVOO4N I O05) |) 12244) ONOS
CAO Ree. TOT OHOOM ONT H OSA GIN OsTON || LOSS) | ovor 1.63
Naz OR elie: ASS TOM On4Onlow42h in O.33.|)) ned.) | OnOS qin o.03
IK AO) sco ie temp ; 4.05 | 4.68 | 3.68 202 Th 1O233 | nid.) Shon 7.58
Oa 0.15 0.49 2.44 | 3.09 | 4.84 1.68 | 3.44 2.93
AO ae ere 0.03 O.1I 0.09} 0.23 OXOZ sie OOM Oni On 28
EVEN O eat sy Trace | Trace | Trace | n.d. Gly) mk, |) G0 |) Gury
|
100.22 |100.25 | 99.85 |100.63 |100.48 |100.17 |100.40 | 99.86
SDRG ree. DV | BOA | QL7e | Beaty 2EOBH 2270 teen Se 2.70
!
I. Unaltered dark-gray flow rhyolite (228 D1 c).
2. Silicified drab spherulitic rhyolite (228 F 2).
3. Pyrophyllitized rhyolite. Matrix of lenses; talc prospect 2 (228 F 3).
4. Pyrophyllitized rhyolite. Matrix of spherulite; tale prospect 1 (222 E 2 j).
5. Pyrophyllite. Light greenish-yellow waxy pyrophyllite from talc prospect 1 (222 E 2 /).
6. Quartz-pyrophyllite schist. Nodule in pyrophyllite (5); talc prospect 1 (222 E 2 ).
7- Pinite; dark dirty-greea waxy, matrix of spherulitic rhyolite. Manuels (228 Dt h).
8. Pinite schist. Matrix of spherulitic rhyolite, Harbour Main (232 E 2 6).
138 A. F. BUDDINGTON
indicates that the replacing mineral is pyrophyllite, it has been
calculated as that alone. Owing also to the lability of error
involved in assigning the elements of the pinitic rocks to the correct
minerals in the right proportions, only a rough estimate of their
mineral composition is given. The iron oxides and magnesia of
No. 7 must be present as an integral part of the white mica molecule,
as no other mineral except quartz can be distinguished in thin
section.
TABLE II
RECALCULATED ANALYSES ©
| Quartz Orthoclase Albite Anorthite |Pyrophyllite oe eae White Mica
1 SEENON c 39.6 29.4 21.4 5 ed oul: eee oe, eee Fy Wed Weer oe er ae
Ore Sees 5367 27.8 9.9 Ea Gi lea ee Sho. eeieuate sayemts
By Botte 28.3 OTe 4.2 0.6 43.6 bay OPEN FE A AS te
TS Be beg cc 18:7 Tae3 3.6 Zs 61.1 0.8 “bean ee
Since Teg) |Secte aceck Stee seta vetoes 91.8 1.6 5-3
ORI LST P7 HEN Penta Stan mies ME Oe ol Oh A RBI, este 33-4 O.9' reece
Teas Present - [hss hinvacua|aacher ieee tell okt Stes Sei ae lee oes About 75
per cent
Ss ae Present’ || Present. || Present 71). 2's see] ses ee eee About 60
per cent
PETROGRAPHY
No. 1 (228 D 1c). This specimen was taken near the top of a
50-foot banded reddish-gray felsite flow. In thin section the tex-
ture varies from microfelsitic to very minutely microcrystalline and
the flow lines are marked by hematite dust. The flow lines are
sharply curved and crenulated and several are replaced by quartz,
especially in the loops of the curves, so that the rock analyzed
as representing the composition of the original rhyolite only approxi-
mates such an unaltered condition.
No. 2 (228 F 2). This rock is a drab to fawn-colored micro-
spherulitic rhyolite with secondary iron oxide in veinlets and specks.
In thin section the groundmass is a finely microcrystalline aggregate
of quartz and orthoclase, with fan-shaped microspherulitic areas.
Secondary quartz is present as grains and lenses, as well as replacing
portions of the spherulitic aggregates. A minute amount of sericite
and quartz occurs along fractures.
HYDRON SILICATES IN ROCKS OF CONCEPTION BAY 139
No. 3 (228 F 3). This specimen, a pyrophyllitized rhyolite,
was taken from the slightly sheared matrix surrounding lenses of
white rhyolite (Fig. 2) adjacent to pyrophyllite veins at talc pros-
pect 2. In thin section the rock shows as a microcrystalline
aggregate of granular quartz and feldspar and of scales and fibers
of pyrophyllite in about equal amounts.
Fic. 5.—Perlitic structure preserved in pyrophyllitized rhyolite. Ordinary
light, X60.
No. 4 (222 E 27). This is the matrix, a pyrophyllitized rhyo-
lite, in which a 6-inch spherulite was found essentially unaltered.
In thin section the rock consists of an aggregate of very minute
microscopic scales of pyrophyllite, complete except for a remark-
ably well-preserved perlitic structure, outlined by microcrystalline
quartz with probably some orthoclase (Fig. 5). The rock is in a
much more advanced stage of alteration to pyrophyllite than the
preceding specimen.
No. 5 (222 E 2f). Light greenish-yellow pyrophyllite with a
fair cleavage. In thin section the rock is seen to be composed of
140 A. F. BUDDINGTON
a homogeneous felt of exceeding minute microscopic scales and
fibers of pyrophyllite, with a strong tendency toward a very good
alignment parallel to the cleavage in a section at right angles to
it and with long, parallel, fibrous shreds in a section approximately
parallel to the cleavage.
No. 6 (222 E 2g). A white quartzose nodule or lense of quartz-
pyrophyllite schist about 1 foot in diameter taken from a pyro-
phyllite vein at talc prospect 1. In thin section the rock presents
what might be called a micro-blotchy groundmass composed of
aggregates of either microcrystalline quartz or of scales of pyro-
phyllite. Some fibers of pyrophyllite also occur interstitially in
the quartz areas.
No. 7 (228 D 1h). This is the dark grayish-olive, waxy-
lustered matrix of the spherulitic rhyolite illustrated in Fig. 4. In
thin section the rock is seen to consist of an aggregate of extremely
fine shreds and scales of white mica with lines of partially replaced
microcrystalline quartz which are probably replacements of certain
of the original rhyolite flow lines not yet entirely replaced by the
white mica.
No. 8 (232 E 2 6). Grayish-olive pinite schist with small
unaltered spherulites or spherulites partially replaced by quartz.
In thin section the material appears as a perlitic microcrystalline
groundmass of quartz and orthoclase partially replaced by sericite.
The perlitic cracks are outlined by threads of sericite fibers, as
illustrated in Fig. 6, and they often form the boundaries of sero-
citized areas which present the appearance of eyes, sometimes with
a reticulating network of sericite veins connecting two adjacent
eyes. Within the sericitic material, isolated microspherulites,
clusters of microspherulites, and long axiolites are often preserved
intact. A few phenocrysts of orthoclase are present and are
remarkably fresh, although occasionally flecked with sericite. The
secondary material consists of an aggregate of microscopic sericite
scales and fibers associated with grains and areas of secondary
quartz. Minerals originating through decomposition at the sur-
face are completely absent except for a trace of iron oxides in the
groundmass and a slight cloudiness in the feldspars, probably due
to kaolin.
ee,
HYDRON SILICATES IN ROCKS OF CONCEPTION BAY 141
PRELIMINARY SILICIFICATION
The first process of alteration which operated on the Avondale
Volcanics was that of regional silicification. On these preliminary
silicified rocks a local series of alterations, those of pyrophyllitiza-
tion, pinitization, and further local silicification, were superimposed.
Fic. 6.—Perlitic structure preserved in pinitized rhyolite. Ordinary light,
X35. m=microspherulites; p=pinite.
This is evidenced by the following data: (1) few later quartz —
veins are found traversing the pinite, quartz schists, or pyrophyllite;
(2) fragments of breccia in the volcanic breccias often exhibit
quartz veins which stop abruptly at the contact with the matrix,
and (3) under the microscope aggregates of sericite scales are found
replacing granular quartz which had previously replaced the heart
of a spherulite, and these sericite scales finger into and inclose
unreplaced fragments of quartz, proving definitely their later
origin.
142 A. F. BUDDINGTON
The spherulitic rhyolites are the rocks which exhibit most
clearly the manner in which the silicification has taken place.
The silica here is present for the greater part as a milky-white
chalcedonic quartz, but vitreous, granular, and white vein-like
quartz as well as quartz crystals are common. The chalcedony
usually forms the outer borders of the concentric crescent-shaped
areas, and of the hearts of the replaced zones of the spherulites,
while the inner portion may be recrystallized to form comb struc-
ture through the interlocking of quartz crystals, or little geodes
with terminated crystals projecting into a small cavity, or granular
vitreous quartz. When only one form of the silica is present it is
very generally of a chalcedonic nature. It is interesting to note
that while at Manuels it is the spherulites of the rhyolites which
are most generally replaced, at Clarenville it was the groundmass
which was replaced instead of the spherulites, because of the
perlitic structure of the former offering the most favorable surfaces
for attack. The banded rhyolites are often lined or streaked with
quartz veins parallel to the planes of flow, which in some cases are
a result of replacement and in others of vein filling. In thin
section, lenses, lines, and granules of secondary quartz are found
to be a common characteristic of the slightly silicified banded
flows. Fig. 7 illustrates the preservation of the perlitic structure
in the quartz which is replacing the groundmass of a spherulitic
rhyolite from Clarenville. The perlitic cracks are outlined by
sericite.
That the silicification of the rhyolites has been due to secondary
metasomatic processes and is not a primary phenomenon is indi-
cated by (1) the interruption of fluxion lines by the replacing
quartz, (2) by the presence of unsupported fragments of unreplaced
rhyolite in the quartz areas, and (3) by the preservation in the
quartz of original structures of the rhyolite, such as the perlitic
structure.
The first stage then in the alteration of these volcanics has
consisted in the silicification under relatively static conditions by
hot siliceous waters of rhyolite flows which may be represented as
having had a similar chemical composition to the present relatively
unaltered gray felsites. Analysis No. 1 may be taken as the com-
HYDRON SILICATES IN ROCKS OF CONCEPTION BAY 143
position of the original rock from which the silicified rhyolite
represented by analysis No. 2 has been derived.
Chemically this has resulted in a decrease in the percentages of
potash, soda, lime, and alumina, an increase in the percentage of
silica, and a relative decrease in the percentage of sodium with
respect to potassium. ‘The process operated through the replace-
ment of the feldspars by quartz and a relatively more rapid
Fic. 7.—Perlitic structure preserved in quartz replacing the groundmass of a
spherulitic rhyolite. Ordinary light, X35. s=spherulite.
replacement of the soda feldspars than of the potash feldspars.
The solutions which effected this alteration doubtless belonged to
the same general period of volcanic activity as the extrusion
of the lavas themselves.
PYROPHYLLITIZATION, PINITIZATION, AND SILICIFICATION
As has been remarked before, a later series of local alteration
processes has been superimposed on the already widespread slightly
siliciied volcanics. ‘The origins of the pyrophyllite, the pinite, and
144 A. F. BUDDINGTON
the quartz-pyrophyllite or quartz schists are so intimately inter-
woven that all may be treated together.
The proof that these rocks have originated through replace-
ment is based on the following data: (1) the preservation of the
structures of the primary rock in the secondary rock, (2) the pres-
ence of unattached and unsupported portions of the country rock
within the replacement products, (3) the introduction of large
quantities of some elements and the solution of others without any
notable change in volume or porosity, (4) gradational contacts,
and (5) the massive homogeneity of all the rocks, and especially
of the pyrophyllite, which does not show the foliated crystalline
structure so characteristic of pyrophyllite veins which fill pre-
existing fractures. To quote examples which belong to the first
category, we find the following structures preserved in pyrophyll-
itized rhyolite: (1) flow structure, (2) spherulites, (3) pebbles of a
partially replaced conglomerate, and (4) perlitic structure (Fig. 5);
these in the quartz-pyrophyllite rocks: (1) spherulites and (2)
breccia structure; the following in pyrophyllite: (1) fragments
of volcanic breccias, (2) pebbles of conglomerates, and (3) spheru-
lites; while in the pinite and pinite schists we have preserved
spherulites, traces of flow structure, axiolites, microspherulites,
and perlitic structure (Fig. 6). Additional evidence of replace-
ment is found in the inclusions and stringers of country rock
within the pyrophyllite veins and the intimate manner in which
the two are often intermixed. Not only this most convincing
field evidence but chemical considerations prove almost conclu-
sively that these rocks must have originated through replacement
of rhyolite or rhyolitic volcanics.
From a study of the foregoing field and chemical evidence, con-
clusions have been drawn as to the genetic relationships of the
eight different rocks described under ‘‘Chemical Analyses”? and
‘‘Petrography,”’ and as to the succession of processes which pro-
duced them. This relationship is graphically represented by the
following diagram, in which the numbers refer to the chemical
analyses given under ‘‘ Chemical Analyses,”’ which may be taken as
typifying the composition of the respective rocks:
HYDRON SILICATES IN ROCKS OF CONCEPTION BAY 145
(z) Gray Rhyolite
Dp
“101
uoly Roy
Vv
(2) Silicified Rhyolite
do1Ag
lox
Va
(3) Pyrophyllitized
Rhyolite
(4) Pyrophyllitized
Rhyolite
UOI}eZ
V \
(6) Quartz-pyrophyllite | (5) Pyrophyllite (7 and 8) Pinite
Schist
TEMPERATURE OF FORMATION OF PYROPHYLLITE
Clapp (1914, 120) assumes that alunite and pyrophyllite are
probably developed only under moderate conditions of pressure
and temperature such as exist near the surface. Although this
is a common mode of origin for both alunite and pyrophyllite, it is
certainly not the only set of conditions under which the latter
forms.
For instance, pyrophyllite is noted by Dana (1909) as a mineral
often forming the base of schists and gneisses, and by Lacroix
(1895) as a mineral of the crystalline schists and Paleozoic meta-
morphics.
Artificially, K. von Chrustchoff (1894) obtained what he
believed to be pyrophyllite by heating gelatinous silica, gelatinous
alumina, and gelatinous zirconium hydrate in a platinum tube at
146 A. F. BUDDINGTON
increasing temperature for six days. The product obtained was a
zirconia-bearing pyrophyllite. Its specific gravity was 2.87 and
it appeared in thin hexagonal plates, which he states are not true
hexagonal plates unless there be optical anomalies.
ALO; ZrO2 | H.20 | Total
23.76 14.54 | 7.86 | 99.81
Le Chatelier (1887) determined the points at which pyrophyllite
loses its water by noting the points at which the temperature
remained constant with absorption of heat and found two such
points, the first at 700° and the second at 850°.
From the foregoing data it is evident that pyrophyllite is a
mineral which may form under conditions varying from the high
temperatures of dynamic metamorphism to the near-surface tem-
peratures and pressures of solfataric agencies.
TEMPERATURE OF FORMATION OF PINITE
Pinite, if considered as an impure sericite, as suggested by
Clarke (1911), has a varied range of conditions under which it may
form. Clarke states, however, that ‘‘the alteration [to sericite] is
most conspicuous in regions where dynamic metamorphism has
been most intense, high temperature, the chemical activity of
water and mechanical stress all working together to bring it
about.”
A green micaceous mineral described as mariposite by Silliman,
and whose composition, shown by two analyses, as suggested by
Hillebrand (1895), resembles pinite, is characteristic of the mother
lode in Tuolumne and Mariposa counties, California.
Crosby (1880) describes pinite as a product of surface decom-
position of petrosilex and felsites in the vicinity of Boston, Massa-
chusetts. Bell (1887) found it at Ballater Pass interspersed through
granitic rocks and along their joint planes, and ascribes its origin
to the decomposition or alteration of orthoclase feldspar, an inter-
mediate stage in its conversion into kaolin.
HYDRON SILICATES IN ROCKS OF CONCEPTION BAY 147
Cole (1886) describes pinite occurring as an alteration product
of spherulitic rhyolites, in conjunction with silicified spherulites.
He suggests that thermal waters are responsible for the origin of
both the pinite and quartz.
From these references it is evident either that there is a differ-
ence of opinion as to the conditions under which pinite forms, or
that it is stable under widely variant temperatures and pressures.
It is probable, however, that it demands higher temperatures and
pressures than exist at the surface as conditions for its most favor-
able development, and such is doubtless the case with respect to
the pinite of Conception Bay.
ALTERNATIVE DEVELOPMENT OF PINITE OR PYROPHYLLITE
Since sericite or pinite is the usual product of hydrothermal
alteration it is pertinent to inquire if any reason can be found why
in certain cases pyrophyllite should be the product formed. A
possible equation (1) representing the formation of sericite from
orthoclase is quoted from Clarke (1911), and a similar possible
equation (2) representing the formation of pyrophyllite from ortho-
clase is given below:
Gp) 56 ST Or HO 2A Or 2 Oe
(2) 6 KAISi,0Os+3H.0s 6HAISi.0.+3K.Si0+3510,
(pyrophyllite)
From these equations three factors are suggested as the possible
elements influencing the alternative development of sericite and
pyrophyllite: (1) the effectiveness of hydrolysis, (2) the mass
action of the excess silica in solution, and (3) the mass-action effect
of excess potash in solution. The dominance of the first two
factors would be conducive to the formation of pyrophyllite, and
the dominance of the third factor would be favorable to the pro-
duction of sericite. This may be illustrated more graphically,
without however implying anything as to the actual mode of opera-
tion, by writing the equation for the formation of pyrophyllite from
sericite as a balanced reaction: .
2KH,AI,Si,O,.+6Si0.+H.O = 6HAISi,05+K.Si0,
(sericite) (pyrophyllite)
148 A. F. BUDDINGTON
If now the quantity of silica is present in the solution in large enough
excess and the effectiveness of hydrolysis is relatively stronger, the
reaction will produce pyrophyllite:
2KH.ALSi,O,.+-6Si0,+ H.0 > 6HAISi,05--K.SiO,
(sericite) (pyrophyllite)
while if K.SiO, or potash in some other form is present in large
enough quantity the alternative reaction will take place and sericite
will be produced:
6HAISi,06+K.SiO, > 2KH.AI,Si,0;,+6Si0,.+-H.O0
(pyrophyllite) (sericite)
CHEMICAL PHENOMENA CONNECTED WITH ORIGIN OF PYROPHYLLITE
From a comparison of the analysis (No. 2) of the silicified rhyo-
lite with that of the pyrophyllite (No. 5), it will be seen that the
change in composition has been such as might have been brought
about essentially through three processes: (1) the introduction of
alumina, (2) the replacement of the alkalies by hydroxyl], and (3) the
solution of silica. The analyses 2, 3, 4, and 5, recalculated into
their mineral composition, show a direct transition from the country
rock (the silicified rhyolite) into pyrophyllite through a decrease
in the quantity of quartz, feldspars, and impurities and a simul-
taneous increase in the content of pyrophyllite. In order that the
original rock may be so altered as to give the mineral analyses
shown by the transitional rocks, it is necessary that metasomatic
replacement of both the quartz and the feldspars should have pro-
ceeded synchronously and at a much faster rate with respect to the
quartz than with respect to the feldspars. This process would
involve the introduction of large amounts of alumina, the gradual
replacement of the alkalies by hydroxy] at a more rapid rate in the
case of the soda than of the potash, and the solution of portions of
both the silica existing in combination with other elements in the
rock and that present as free quartz.
The heterogeneous, blotchy character of the quartz-pyrophyllite
rock when seen in thin section suggests that the rock may have
been in the condition of a more or less homogeneous glass when
acted upon by the silicifying and pyrophyllitizing solutions, in view
of the fact that its chemical composition and mineral arrangement
HYDRON SILICATES IN ROCKS OF CONCEPTION BAY 149
would involve the simultaneous replacement of the feldspars of
a crystalline rock by silica and pyrophyllite, and of its quartz by
pyrophyllite.
ORIGIN OF PINITE AT MANUELS
From a further study of the chemical analyses, it becomes
evident that while the silicified rhyolites, pyrophyllitized rhyolites,
and pyrophyllite have all decreased in their content of iron, mag-
nesium, potassium, and soda, the pinite analysis (7) shows a decided
increase in the first three of these elements. During the formation
of pyrophyllite vast quantities of potash must have been liberated
and carried in solution in the circulating waters. Is it not possible
that away from the main channels these waters deposited their
load as pinitic replacements of the rhyolite under the control of
lower temperatures and pressures and the mass-action effects of
the excess potash in solution? It seems reasonable to suppose that
the pinite here was an essentially contemporaneous formation
with the quartz-pyrophyllite schists and pyrophyllite, receiving
some of the magnesia, potash, and iron released by the formation
- of the pyrophyllite, as the quartz schists have received some of the
silica originating at the same time.
ORIGIN OF THE PINITE SCHIST AT HARBOUR MAIN
The chemical analysis of the pinite schist recalculated for
sericite gives the rock a mineral composition of about # sericite
and ? quartz, feldspar, and other constituents. Examination of
thin sections shows that this result has been brought about through
the replacement of both the feldspar and quartz by sericite. If
we consider the rock previous to pinitization to have had the com-
position of the silicified rhyolite (No. 2), then the process cited
involves the substitution of potash for soda in the feldspars, the
addition of potash and alumina, and the subtraction of silica and
soda.
There is considerable evidence that this rock was not formed
at the surface. There are no secondary products of decomposition,
such as kaolin or limonite, associated with the pinite. It occurs
in quantity only in certain zones and extends to a considerable
depth, as exposed in a prospect pit for talc, south of Harbour Main.
150 A. F. BUDDINGTON
Where it occurs as patches or specks it bears no apparent relation
to the surface. Furthermore, the pinitic material has undergone
dynamic metamorphism and is sheared and cleaved, while chemi-
cally its origin involves the introduction of alumina and potash
through replacement.
GENERAL OBSERVATIONS
It is quite probable that the foregoing processes operated under
conditions of some dynamic movement, as their characteristic
development is along shear zones, and their products assume a
lenticular structure which is as characteristic of the minuter struc-
tures of the rocks as of the veins themselves. Moreover, the
rocks themselves have been sheared and possess a more or less
prevalent cleavage, conditioned by the growth of their constituent
minerals in more or less parallel arrangement.
It is probable that the factors determining which of these three
rocks—pyrophyllite, pinite, and quartz-pyrophyllite—shall form are
to be found in the temperature, pressure, and chemical content of
the solutions themselves, in the relative effectiveness of hydrolysis,
and in the mass-action effects of the compounds in solution.
The concentration of the potash in the pinite, and the silica in
the quartz-pyrophyllite rocks may be accounted for on the theory
of a redistribution of the elements, but the tremendous contribu-
tions of alumina represented by the pyrophyllite, and to a minor
extent by the pinite, must be accounted for otherwise. The close
connection between the pyrophyllite deposits and the granite-
Avondale Volcanics contact south of Manuels and between the
pinitized rhyolites and the Woodfords monzonite stock is hence of
significance. It may be that there is no genetic connection between
these minerals and the intrusives, and that their formation was
entirely dependent on the locus of fault zones in those localities.
But there are numerous other profound fault and shear zones in
this area with no exceptional alterations.
Hence it seems probable that when faulting took place between
the volcanics and the intrusive granite or monzonite, the still hot
magmatic waters were released and found their way upward along
these fault zones, either contributing the alumina directly, or per-
HYDRON SILICATES IN ROCKS OF CONCEPTION BAY 151
haps indirectly through mingling with already aluminous solutions. _
Such solutions, if present, would be those which had accomplished
the silicification of the volcanics with their attendant solution of
alumina under static conditions and hence before the period of
orogenic movement, which folded the volcanics and witnessed the
intrusion of the plutonic batholith and stock. The evidence bear-
ing on the exact dates of the periods of faulting and folding, however,
is not conclusive.
COMPARISONS WITH OTHER DEPOSITS
Comparisons with other deposits show that, according to the
descriptions, the pyrophyllite deposits of the Pambula goldfield,
New South Wales, and of Chatham and Moore counties, North
Carolina, are essentially similar to those in Newfoundland, and it
is here suggested that possibly they have had a similar origin. ©
Clapp (1914) described quartz-pyrophyllite rocks from Kyuquot
Sound, Vancouver Island, which may be taken as a type of pyro-
phyllite deposits developed by solfataric agencies under conditions
of temperature and pressure existing near the surface; while those
of Newfoundland are a type originating under intermediate con-
ditions of temperature and pressure.
In the first case the pyrophyllite rocks are associated with
alunite and in the latter case with pinite. In the Kyuquot deposits
the original quartz of the replaced dacite has not suffered any loss
except in one doubtful case, while the distinctive feature of the
Newfoundland rocks has been the replacement of quartz in rhyolites
by pyrophyllite.
The two deposits are similar in that, in both cases, the rocks are ~
associated with intrusive batholiths, the one with a feldspathic
quartz diorite and the other with granite. Both are metasomatic
replacements of acid volcanics, while in the zone of alteration there
seems to have been some transfer of material, and soda, lime,
magnesia, and iron oxides have been lost in each case.
CONCLUSION
From the foregoing evidence the conclusion may be drawn that:
the pyrophyllite, pinite, and quartz-pyrophyllite schists of the
152 A. F. BUDDINGTON
Avondale Volcanics owe their formation to metasomatic replace-
ment and alteration of previously silicified rhyolites or rhyolitic
volcanics by thermal waters, under conditions of dynamic stress
and intermediate temperatures and pressures, operating along
channels primarily determined by fault or shear zones. Chemi-
cally, the salient features of these alterations have been the intro-
duction of alumina, the more or less complete substitution of the
hydroxy! element in place of the alkalies, and the solution of soda.
The solutions instrumental in causing these alterations may have
been to a greater or less extent juvenile waters emanating from
the intrusive granite batholith and monzonite stock at some
period subsequent to the time of their injection.
May, 1915
BIBLIOGRAPHY
Bell, W. H. ‘“‘New Localities for the Mineral Agalmatolite with Notes on
Its Composition,” Miner. Mag., VII (1887), 28.
Chrustchoff, von K. ‘Artificial Zircons,” abstract in Miner. Mag., X (1894),
250.
Clapp, C.H. “The Geology of the Alunite and Pyrophyllite Rocks of Kyuquot
Sound, Vancouver Island,” Summary Rept. of the Geol. Surv., Dept. of
Mines, for 1913 (1914), pp. 109-26.
Clarke, F. W. “Data of Geochemistry,” U.S. Geol. Surv., Bull. 491 (1911),
p..567.
Cole, G. A. J. “On the Alteration of Coarsely Spherulitic Rocks,” Quart.
Jour. Geol. Soc., XLII (1886), 186-87.
Crosby, W. O. “Pinite in Eastern Massachusetts, Its Origin and Geologic
Relations,’ Am. Jour. Sci., 19 (1880), 116.
Dana, E.S. A System of Mineralogy (1909), p. 601.
Hillebrand, W. F. Quoted by H. W. Turner (1895).
Howley, J. P. Geologic Map of Newfoundland (1907).
* Lacroix, A. Minéralogie de la France (1895), I, 471.
Le Chatelier, M. H. ‘De l’Action de la chaleur sur les argiles,”’ Bull. Soc.
Min. France, X (1887), 207.
Powers, F. D. “The Pambula Gold Deposits,” Quart. Jour. Geol. Soc.,
XLIX (1893), 233-35.
Pratt, J. H. ‘Talc and Pyrophyllite Deposits in North Carolina,’ V.C. Geol.
Surv., 1900, Economic Paper No. 3, pp. 23-29.
Turner, H.W. “Further Contributions to the Geology of the Sierra Nevada,”
U.S. Geol. Surv., 17th Ann. Rept., 1895. Part 1, p. 520.
THE ORIGIN OF RED BEDS
A STUDY OF THE CONDITIONS OF ORIGIN OF THE PERMO-
CARBONIFEROUS AND TRIASSIC RED BEDS OF
THE WESTERN UNITED STATES:
C. W. TOMLINSON
University of Minnesota
PART I
PREFACE
SUMMARY DESCRIPTION OF THE FEATURES CONSIDERED
List of Formations
Colors of Gypsum and Limestone
Color in Clastic Strata
Distribution of Greenish Colors
Nature of the Coloring Matter
Is THE FERRUGINOUS MATERIAL AN ORIGINAL CONSTITUENT OF THE SEDI-
MENTS, OR A LATER INTRODUCTION ?
Hypothesis of Introduction of Iron from Igneous Magmas
Later Introduction of Iron by Meteoric Waters
Deposition of Coloring Matter Contemporaneous with Sedimentation
Microscopic Evidence
Extent of Known Secondary Redistribution of Coloring Matter
Is THE FERRUGINOUS MATERIAL IN THE SAME FORM AS AT THE TIME OF
SEDIMENTATION ?
Variations in Degree of Oxidation
Origin of Mottling
Cause of Gray and Green Bands in Red Beds: Barrell’s Hypothesis
Organic Matter the Controlling Influence in the Case of the Western Red
Beds
Variations in Hydration of Ferric Oxide
WAS THE COLORING MATTER A CHEMICAL OR A MECHANICAL SEDIMENT ?
t A revision of a thesis presented in partial fulfilment of the requirements for the
degree of Master of Arts at the University of Wisconsin, in June, ro14.
153
154 C. W. TOMLINSON
PART If
CONDITIONS OF DEPOSITION OF RED CLASTIC SEDIMENTS: MODERN TYPES
Red Clay of the Deep-Sea Bottom
Stream Deposits Derived from Pre-existing Red Beds
Arkosic Stream Deposits
Stream Deposits Deriving Their Coloring Matter from Ferruginous
Residual Soils
Terrigenous Marine Clastics
Deposits of Desert Lakes or Playas
Red Dune Sands
EVIDENCE OF FEATURES OTHER THAN COLOR AS TO THE CONDITIONS UNDER
WHICH THE RED BEDS WERE DEPOSITED
Evidence of Conglomerates as to the Sites of Land-Masses
Significance of Non-clastic Sediments
The Clastics: Minor Structural Features
The Clastics: Mineral Composition
Evidence Supplied by Fossils
Summary
RELATION OF OROGENIC HISTORY TO RED BEDS SEDIMENTATION
SUMMARY
RAR SI
PREFACE
Certain general facts concerning the origin of the western Red
Beds have been known for some time and have become incorpo-
rated into current textbooks. There has been, however, much
difference of opinion in the interpretation of some features of this
remarkable group of sediments, especially as to the significance of
the color itself. This paper is devoted to an investigation of the
causes and history of the coloring matter, which, more than all
other features put together, distinguishes the Red Beds from other
sedimentary series.
The investigation on which this paper is based’has been chiefly
a study of the literature to which reference is made in the footnotes,
together with all available published descriptions of the western
Red Beds, and much miscellaneous literature dealing with related
subjects. The writer’s first-hand acquaintance with the Red
Beds has been gained from two summers of field work in Wyoming
and Idaho (under the direction of Eliot Blackwelder, of the United
THE ORIGIN OF RED BEDS 155
States Geological Survey), and from laboratory study of thin
sections. For valuable suggestions and criticism and for review of
the manuscript the writer is indebted to Messrs. Eliot Blackwelder,
A. N. Winchell, W. J. Mead, and F. T. Thwaites, of the University
of Wisconsin; to Messrs. W. H. Emmons, C. R. Stauffer, F. F.
Grout, C. J. Posey, and A. W. Johnston, of the University of
Minnesota; and to Dr. R. D. Salisbury, of the University of
Chicago.
SUMMARY DESCRIPTION OF THE FEATURES CONSIDERED
List of formations.—Clastic sedimentary strata of reddish color
outcrop or constitute the uppermost part of the bedrock over about
4 per cent of the area of the United States and exist beneath a
cover of younger sediments under an additional area probably twice
as large. Much the greatest volume of such strata is included in
the single group of rocks which forms the subject of the present
study: namely, those Red Beds which outcrop in many areas from
Kansas and Texas to Arizona and Montana (Fig. 1). The forma-
tions included in this group are related closely in age, ranging
from Pennsylvanian to Triassic, or possibly Jurassic, and are prob-
ably for the most part physically continuous. They comprise the
Cimarron series of Kansas and Oklahoma, and the Wichita, Clear
Fork, Double Mountain, Greer, Quartermaster, and Dockum beds
of Texas; the Wyoming, Fountain, and Maroon formations of
central Colorado; the Cutler and Dolores of southwestern Colorado;
the Aubrey, Shinarump, Vermilion Cliff, and Moencopie of the
Colorado Plateau, with the Saliferous and Zuni of the Zuni Plateau
in New Mexico; the Spearfish, Opeche, and Chugwater of Wyoming
and southern Montana; and the Ankareh and Nugget of south-
eastern Idaho and northeastern Utah.
Similar Red Beds constitute a large part of the sediments of the
Newark series (Triassic) of the Appalachian Piedmont region—
typified by the Stockton and Brunswick formations of New Jersey."
They make up also, among others, much of the Catskill formation
(Devonian) of eastern New York and Pennsylvania; the Medina
and Clinton (Silurian) of New York; the Vernon shale (Silurian, a
«See H. B. Kiimmel, Ann. Rept. of the State Geologist of New Jersey, 1896.
TOMLINSON
W.
C.
Sprg pay W19}SeM IY} Jo UOTNALYsIp Surmoys deyy—'t “ony
"uo1s04q fq penouay Fea |
suclyouso} sabunch yjveusg pring lm |
aovfang ye pesedxy | ss
“S$d3g G4u NYSLSAM SHL
SPW 49 2189S
uoy1d2foig 21U05 243 UD
(sm) VOIMAWV |
mae
hie
WE
|
is
ose ieee
THE ORIGIN OF RED BEDS Ts5 7,
member of the Salina beds), the Bedford shale (Mississippian), and
the Dunkard series (Permian) of Ohio; the Lake Superior sand-
stone (probably Algonkian) of northern Michigan, Wisconsin, and
eastern Minnesota; and the Belt series (Algonkian) of Montana and
British Columbia. Occasional reference will be made in this paper
to these formations, and to Red Beds in other countries as well; but
this discussion applies especially to the western group, with which
the writer is most familiar. '
Colors of gypsum and limestone.—The beds of gypsum occurring
in many areas of Red Beds strata are described everywhere as
remarkably pure and white, except where stained by a red coating
washed down from overlying clastic sediments. The same is true
of a majority of the limestones and dolomites occurring in the red
series, most of which are gray or drab or bluish on fresh fracture.
Even the famous Redwall limestone (2,500 feet thick) underlying
the Aubrey Red Beds of the Grand Canyon section is gray on
fresh fracture; its surface color is due to concentration of iron oxide
by weathering, to wash from above, or to both of these causes.
Exceptions are found in limestone or dolomite bands in the lower
Chugwater in Wyoming,’ and in the Minnekahta limestone? of the
Hartville quadrangle, which are characteristically purplish or rosy
gray; and locally in certain limestones in northern Oklahoma,
where they are in transition to sandstone.* These limestones are
in most localities nearly or quite barren of fossils.
Color in clastic strata.— Another and perhaps a yet more signifi-
cant fact is the variation of hue among the clastic strata. Inter-
bedding of greenish, gray, or buff beds with red sediments is found
in a majority of Red Beds sections; notably in the Saliferous of the
Colorado and Zuni plateaus, in the Dockum group of Texas, and in
« G. K. Gilbert, ‘Geology of Portions of Nevada, Utah, California, and Arizona,”
U.S. Geog. Surveys W. of the tooth Meridian, III (1875), 177-78.
2 Eliot Blackwelder and C. W. Tomlinson, “Field Notes on Work in Western
Wyoming, roto and 1011,” unpublished; property of the United States Geological
Survey.
3W. S. T. Smith; Hartville Folio (No. 91), Geol. Atlas of the U.S., U.S. Geol.
Survey, 1903.
4J. W. Beede, ‘‘The Neva Limestone in Northern Oklahoma,” Okla. Geol. Survey
Bull. No. 21, 1914, p. 24.
158 C. W. TOMLINSON
the Red Beds of the San Juan region and of the Anthracite, Crested
Butte, and Tenmile quadrangles of Colorado. Alternation of
paler with darker and with brighter shades of red is remarked in
almost every occurrence of Red Beds. In all these instances it is
significant that the color boundaries tend to follow bedding planes,
LEG
INES
Put ple Plates
an apr ee e
IS Blark |Slates
2 aks SI f
o Be aN
nh . ‘
ef Aves *,
< oS e he SSK
= es Red ate c H Ba RS ‘
¢ i: Be ie
° aN VS
= cy £ NG
o 7\. (2) xx x
Swe RAS w Be
: Lf y 4 \ Ee oe
»/ \4AY we
i ee Ve Sa
~ ry x \x Ne
*9 d ™ < ES eA
an
SSS ee EN “
rf c < bs Af a S
x x x
of \e ss ver > N mane
\
‘
‘
£3¢
\
N
.
x
5
=
sg
i
a
3
Iv
a
7
N
x
X
\
N
‘
‘
\
Beery lt eh
2 3
Percent of Ferrous Iron (Fein FeO).
Fic. 2.—Diagram to illustrate the relation between color and the proportion of
ferric to ferrous iron in ferruginous slates. Analyses (from Dale) are lettered to
correspond with text:
and usually accompany changes in coarseness of grain. Many of
the color boundaries are distinct, even planes, but they may be
rendered irregular by downward migration of coloring matter.
Where alternations of light- and dark-red strata occur, the
more deeply colored beds are in most cases of finer grain than the
THE ORIGIN OF RED BEDS 159
others. The occurrence of coarse-grained massive buff sand-
stones in a series of maroon or chocolate shales has been noted by
many writers. ‘This association holds true in many other Red Beds
besides the group here under consideration. Thwaites' reports it
as an almost unfailing relation in the Lake Superior sandstone
series of northern Wisconsin, and Geikie? mentions its existence in
_ the Triassic New Red Sandstone of Great Britain. The respective
tints are understood to be uniform throughout the strata in which
they are noted, and not to be merely the surface staining of the
beds, which might have a very different origin.
Distribution of greenish colors.—Greenish tints occur in the Red
Beds as a fairly even color through continuous beds interstratified
more or less closely with red strata, in streaks and blotches in red
strata themselves, and occasionally in strips following joint planes.
The completely greenish strata, and likewise the mottled beds,
include both shales and sandstones, and are described from many
districts. Green spots in red strata are as a rule irregularly
ellipsoidal in shape, somewhat flattened parallel to the bedding,
and indefinite in outline. They may vary in diameter from a few
millimeters to several inches.
Variations in color along the strike are as common and as much
to be expected as similar variations in texture, cross-bedding, or
any other stratigraphic feature. The Red Beds of the Southwest
are noted for their inconstancy and frequency of change along the
strike; those of Central Wyoming and the Black Hills are fairly
continuous in lithologic characters for considerable distances.
Where other features are variable, the color is variable also; and
where other features are constant, color likewise is constant.
Nature of the coloring matter.—Available data as to the chemical
composition of the green bands and spots and other variations in
color in the western Red Beds are very meager; but many of the
same phenomena occur in roofing slates, whose commercial value
has been the cause of painstaking investigation of their occurrence
and character. The close dependence of color upon chemical
1F, T. Thwaites, ““Sandstones of the Wisconsin Coast of Lake Superior,” Buil.
Wis. Geol. and Nat. Hist. Survey No. 25, 1912, p. 31.
2 Archibald Geikie, Text-Book of Geology (London: Macmillan, 1903), p. 1064.
160 C. W. TOMLINSON
composition is brought out strikingly by the following analyses,
which are at least sufficient to show that the differences in color in
the Red Beds are caused by the same differences in chemical compo-
sition as those which cause corresponding differences in color in
slates. The analyses are plotted graphically in the diagram
(Big. 2).
The following analyses are taken from Dale:’
Fe.0; FeO Net Fe |Ratio Fe’”’: Fe’ Free Carbon
bau (a) yc eu sn chtiane: oe 5-30 I.20 4.69 | 4.04 :1.00
il BaP rc 5.61 1.24 4.89 | 4.09 (No free carbon found
fais Sys Wee ester 3.48 I.42 3.54 2.29 in any of the red or
3 NOP eee 3.86 T44 3.83 | 2.42 purple slates)
1 lad es eee 7.10 1.00 Saas 6.37
Average...| 5.26 it 4.62 giclose” Gitatole)
22 G, eae: 4.10 Dont 4.99 Te e{0) Qamatere)
pies baeoee coe 5.16 2.54 550). lb 84
To 8 Erect oe? 6.63 1.20 5-58 | 5.00
Average...| 5.30 Dy ils Suelo |) Qewe Sige}
AT aa ere 0.81 4.71 Ano 3teal OnD5 05100
S| Biba secre 1.34 5-34 x00)" 102.220 Trace
2 Cece at 1-23 4.73 4.54 ©. 234 Trace
rep WEG tocevare ci Sietecs Ter 6.58 Han. || Ce uss
5 Hin Sechaceal 1.24 6.81 6.16 | 0.165
co Olam arcterae 1.47 3.81 3.99 | 0.348
DG) OB Bo Miers eee Te33 5.64 agi 0.213 Trace
DIVES ae 2.24 4.07 4.73 ©.406
AVETALCs se lsat ss aoe AROOWMEON232n TROO
| et a | 0.52 4.87 4.15 | 0.095:1.00 | 0.46
TE INU cee see ode oe 9.03 7.02 | 0.000 1.79
ao | Re eas 1.98 3.65 4.23 | 0.490 0.77
OU rseter 0.53 3.52 Seu 0.135 1.54
Average...| 0.75 Seo AGO2 | NOnt20).0OOmleteetA
Se ES ric 3.86 1.44 3L03) 242) S100
sa OF esi igare 1.79 1.19 De Sw a | 3 4 le OO
Gans | Ree 1.09 1.06 1.58 | ©.027:1.00
* K2 is same slate as K, but finer grained. M-=red slate near green spot. Q=purple rim of spot.
R=green part of spot.
™T. N. Dale, “The Slate Belt of Eastern New York and Western Vermont,”
Ann. Rept. U.S. Geol. Survey No. 19, 1899, Part 3, pp. 232, 246-53, 257, 264; and
“The Roofing Slates of the United States,” U.S. Geol. Survey Bull. No. 275, 1905,
PP. 34-36.
THE ORIGIN OF RED BEDS 161
The following analyses are taken from W. J. Miller:
VERNON FORMATION, CENTRAL NEW YORK
Fe.0; FeO Net Fe | Ratio Fe’” : Fe”
IRGol Gk es 5-6 o ole emule wmminloe 2.25 0.75 2.16 D2 OO
Green spot in red shale........ 0.00 1.19 0.93 0.00:1.00
The following analyses were furnished by Eliot Blackwelder?
CHUGWATER FORMATION, WIND RIVER VALLEY, WYOMING
Fe.0; | FeO Net Fe Ratio Fe’” : Fe”
Nedisandstone we ee eneee 3.50 T.04 3.26 3.02:1.00
Greenish sandstone*.......... THOR 1.04 T53 0.89:1.00
*The greenish sandstone of the Chugwater in this case is a strip of the ordinary red sandstone,
leached along a joint crack.
The following analyses are taken from Richardson :3
SPEARFISH FORMATION, BLACK HILis
Fe.0; FeO Net Fe Ratio Fe’” : Fe”
(Creentshalesars cesar eee: 1.85 1.04 2.02 I.78:1.00
Red shale, adjacent to green... 4.601 1.24 4-55 BE 721 OO
Redyshal eee aati m seine natal: 3.64 0.65 3.05 5.04:1.00
Wedkshalewieie yee Meee 2.04 0.18 1.57 10. 20:1.00
The black color in the slates is due, not directly to any peculi-
arity of the iron content, but to the presence of carbonaceous
matter, which incidentally brings about the reduction of iron oxide
to the ferrous form. Black shales are very rare in the western Red
Beds, but highly carbonaceous and even coal-bearing strata occur
in the Newark series of the Atlantic Piedmont. The typical
Newark clastics are quite intensely red, many of them with a
purplish tone, but the carbonaceous strata are always gray or black.
The color of the prevailing red strata in the Red Beds series is
due to the presence of ferric oxide. The iron of the coloring matter
tW. J. Miller, ‘Origin of Color in the Vernon Shale,” Bull. N.Y. State Museum,
No. 140, in 63d Ann. Rept. N.Y. State Museum, 1909, 1, 150-56.
2U.S. Geol. Survey, Division of Chemistry, Analysis No. 2530.
3G. B. Richardson, ‘‘The Upper Red Beds of the Black Hills,” Jour. Geol., XI
(1903), 365-93.
162 C. W. TOMLINSON
is chiefly in the ferric state in light- and dark-red, buff, and yellowish
strata. A gray or green color, on the contrary, signifies a low pro-
portion of ferric oxide, and usually a preponderance of ferrous
over ferric compounds. The mineral composition of the coloring
matter is difficult to determine accurately because of its fine division.
A green color is “common with silicates in which ferrous iron is
prominent,’ and silicates may be important where the ratio of
ferrous to ferric iron is high.
IS THE FERRUGINOUS MATERIAL AN ORIGINAL CONSTITUENT OF THE
SEDIMENTS, OR A LATER INTRODUCTION ?
Hypothesis of introduction of iron from igneous magmas.—lt
the ferruginous matter was an integral part of the original sedi-
ments, we have no more difficulty in explaining its presence than in
accounting for any other common mineral constituent of sedi-
mentary rocks. Its source was most probably in the same rocks
which gave rise to other materials of the series, such as quartz, feld-
spar, and calcite, and the agencies of transportation were the same
as those which were responsible for the entire series. If, however,
we postulate that the iron has been introduced since the comple-
tion of sedimentation, after the series of Red Beds was otherwise
complete, we shall find it very difficult to reconstruct in imagina-
tion any natural agency which might have brought about such a
result, and we shall be puzzled to find an adequate source for this
vast amount of iron.
There is one hypothesis of this kind which received credence
and vigorous support in America for several decades of the nine-
teenth century, in explanation of the red stain in the Newark series
of the Connecticut Valley. The close association, in that series, of
clastic red sediments with contemporaneous extrusive and intrusive
basic igneous rocks of great thickness and extent made it a natural
suggestion that the exceptional color of the sedimentary members
was connected directly with igneous action. ‘The absence of any
'E.S. Dana, A Text-Book of Mineralogy (New York: John Wiley & Sons, i909)»
10s 2A
2See J. D. Dana, Manual of Geology, ed. 1880, p. 764; and also his review of
Russell’s bulletin on the “‘Subaerial Decay of Rocks” (U.S. Geol. Survey Bull. No. 52,
1889), in Am. Jour. Sci., 3d Ser., XX XIX (1890), 310.
THE ORIGIN OF RED BEDS 163
strong evidence in support of this hypothesis, aside from that of
association with igneous rocks, and the discovery of various lines
of evidence (among those outlined below) in direct opposition to it,
however, caused it to fall into disrepute. In the case of the western
Red Beds there is not even the association with igneous rocks to
suggest such an explanation. There are no contemporaneous
igneous rocks in any part of the Red Beds group, and in the greater
part of the area in which the group occurs there are no later igneous
rocks known. In no case is there a relation comparable to that
in the Connecticut Newark.
Where the effect of later intrusions upon Red Beds has been
observed carefully, that effect is not to heighten, but to destroy,
the red color. This action has been noted in the Tenmile district*
and in the Anthracite-Crested Butte district,? Colorado.
Later introduction of iron by meteoric waters——There is no
apparent reason why the Red Beds should have been favored by
post-sedimentational iron-bearing solutions while other clastic
series in the same region, both older and younger, were not stained.
It might be expected that the coloring matter would be most
abundant in the most pervious strata, especially along the lower
surface of such strata, where they are in contact with less pervious
rocks. It is quite true that color boundaries in the series follow
bedding planes very closely; but, unfortunately for the hypothesis
of later introduction, the more highly ferruginous strata of the
Red Beds are as a rule, and with few exceptions, the more impervi-
ous. As noted above (pp. 158-59), in a series of alternating sand-
stones and shales it is almost invariably the shales which are
deeper in color.
Ferric hydrates are not being introduced into the Red Beds
strata along the present joint planes. The analyses of Chugwater
sandstone given on p. 161 (see also footnote) show a marked leaching
of iron along a joint. Nor is iron commonly concentrated along
joints in paler sediments underlying the Red Beds.
«S, F. Emmons, Tenmile District Special Folio (No. 48), Geol. Atlas of the U.S.,
U.S. Geol. Survey, 1896.
2G. H. Eldridge, “Description of the Sedimentary Formations,” Anthracite-
Crested Butte Folio (No. 9), Geol. Atlas of the U.S., U.S. Geol. Survey, 1894.
164 C. W. TOMLINSON
Deposition of coloring matter contemporaneous with sedimentation.
—Tf the ferruginous material which furnishes the color was con-
centrated in the sediments chiefly at the time of their deposition,
this association of high color with fine sediment is explained readily,
as follows:
In the weathering of igneous rocks, ferruginous material is
separated out chiefly by the chemical decomposition of iron-bearing
silicate minerals, and is therefore at the time of separation in a very
fine state of division. At the same time ferrous salts of iron usually
are altered to ferric oxide or hydrate. During surface transporta-
tion and sorting it is segregated in whole or in part, by reason of this
fine division (if it persists) and in spite of its high specific gravity,
along with other finely divided materials constituting muds and
“clays.”
This does not apply to iron occurring in the parent rock in the
form of magnetite or other very stable minerals, which in most
cases are concentrated with the coarser products of mechanical
disintegration, such as sands and sandy shales. Ferruginous
materials firmly cemented to sand grains during weathering may
also be transported and deposited with the sand. Iron taken into
solution will have yet a different history.
In the weathering of sedimentary rocks, the behavior of their
ferruginous content is dependent upon the behavior of that material
in a former sedimentary cycle, and thus ultimately upon the con-
ditions already outlined for the weathering of the igneous rocks.
Ferric oxide, the form in which iron occurs most abundantly in
sediments, is, because of those conditions, usually finely divided,
and in a second cycle of transportation and deposition will be con-
centrated again chiefly with the muds. In so far as assortment is
imperfect, the ferruginous material may be deposited with any type
of sediment.
Because of the usual absence of any commercial value in
the series, there is an unfortunate dearth of analyses of Red
Beds shales and sandstones. The fact of the concentration of
ferruginous matter in the fine-grained sediments is well illus-
trated, however, by composite analyses of shales and sandstones
THE ORIGIN OF RED BEDS 165
from all sources. The following figures from Clarke’ are to
the point:
Percentage | Percentage
€:03 FeO Teen
Average of 78 shales (mean of two composites) . . 4.03 2.46 6.40
Composite analysis of 253 sandstones........... 1.08 0.30 1.38
See also analyses K and K’, on p. 160, supra.
Microscopic evidence.—Russell? has presented evidence to show
that the red coloring matter in sandstones of the Newark series in
Virginia occurs as a coating on the sand grains, and that it existed
in that form even before the transportation of the sand from the
residual soils from which it was derived. Since much of his argu-
ment would apply equally well to the red sandstones of western
Red Beds, it is worth investigation in this connection. In a few
thin sections of Newark sediments from Virginia which have been
available for study by the writer, it is shown clearly that ferruginous
matter exists there, both in the form described above and as a
later interstitial filling between grains. Many of the sand grains,
both of quartz and of feldspar, are well rounded. Most of them
are surrounded by a thin coat of hematitic material, whose outer
surface is smooth and even, but whose inner border may show slight
irregularities penetrating into the body of the grain. This red
film may not be entirely continuous around the grain; and this fact,
together with the smoothness of its outer surface, suggests, as
Russell maintained, that the coating was acquired by the sand grain
before its final deposition, and that the coating suffered wear during
transportation, without being completely removed.
In a number of instances it was found that part of the cementa-
tion of the rock had been accomplished by enlargement of the
original grains of quartz and feldspar in optical continuity, outside
of the red coating; and that outside of the enlargements there
existed other bodies of hematitic matter, irregularly scattered
1. W. Clarke, ‘‘The Data of Geochemistry,” 2d ed., U.S. Geol. Survey Bull. No.
491, 1911, chaps. lil, v, vi.
21. C. Russell, ““Subaerial Decay of Rocks,” U.S. Geol. Survey Bull. No. 52, 1880.
166 C. W. TOMLINSON
through the interstitial spaces. This material may have filtered in
during the process of cementation; or it may have been present at
the time of sedimentation and have been thrust out of the way by
the growing crystals during enlargement. Occasional specks of
red-stained material are found within the area of the enlargements
and distinct from the inner coating of the original grains; and where
the enlargement is missing, the interstitial hematitic matter may
be difficult to distinguish from that of the primary coating. The
stained areas probably do not represent pure ferric oxide, but ferric
oxide in such ratio to silica or clayey material as to render the
mixture nearly opaque and quite uniformly red or reddish brown;
for chemical analyses of the same rocks show the percentage of
ferric oxide in the rock to be much lower than the percentage of red-
stained area in the sections.
A similar microscopic investigation has been made by Richard-
son’ in his study of the Spearfish formation of the Black Hills.
He says: ‘Amorphous red pigment is prominent in the slides. It
irregularly coats and spots the minerals, and . . . . constitutes
the chief interstitial substance.”’ He also presents an analysis to
show that the ferric oxide of the pigment is essentially anhydrous.
Thin sections of Red Beds from all parts of the West are not
available at present, and it has not been practicable, therefore, to
make a thoroughgoing microscopic study of the group. Richard-
son’s description suggests a relation of pigment to cementation
similar to that found in the Newark sandstones: a twofold relation,
indicating that part of the pigment was transported and deposited
as a coating on sand-grains, and that the remainder constitutes an
important part of the cementing material of the rock and is coeval
with the rest of that material.
But what was the time of cementation? Was this process com-
pleted before the exposure of the Red Beds series to erosion, or is it
still going on, or did it cease at some intermediate time? In so far
as this question affects the iron content of the Red Beds we really
have answered it already; for if any considerable part of the iron
had been introduced as a cement later than the time of sedimenta-
tion it would not be found most abundantly in the strata which
r Op. cit. 2 Tbid., p. 379.
THE ORIGIN OF RED BEDS 167
afford the least ready passage to water, as is actually the case.
The cementing material of the Red Beds, in so far at least as it is
ferruginous—and the remainder of it has little or no bearing upon
the point in question—was therefore for the most part present in
those beds at the time they were deposited as sediments. |
Extent of known secondary redistribution of coloring matter.—
Although the evidence is convincing that the ferruginous matter in
the Red Beds was an integral part of the original sediment, and
that it was deposited originally in the series in practically its present
distribution and arrangement, it is equally certain that there have
been some later modifications of that primary distribution. A
large majority of all variations of color within the Red Beds are
limited by bedding planes; but there are numerous minor varia-
tions in color due to the migration of coloring matter along the
lines of movement of ground-water." Reducing solutions locally
extract ferruginous matter along joints, or cause a general down-
ward movement of iron. In the western Red Beds, as in Barrell’s
section of the Catskill formation in Schuylkill County, Pennsyl-
vania,” the lower boundaries of many deeply stained bands are
drawn less sharply than the upper. All of these are very minor
features, however, in the distribution of the coloring matter of the
series as a whole. The analyses (p. 161) furnished by Blackwelder
illustrate the effect of leaching along a joint; the color changes from
red to greenish, the net iron content is reduced from 3.26 per cent
to 1.53 per cent, and the ratio of ferric to ferrous iron drops from
BHO2 ICO LOOs60)1 200:
IS THE FERRUGINOUS MATERIAL IN THE SAME FORM AS AT THE
TIME OF SEDIMENTATION ?
Variations in degree of oxidation.—Is the color due to recent
oxidation in weathering? It has sometimes been asserted that the
color of the Red Beds is a superficial matter, due to the weathering
of originally dull-colored sediments. In support of this idea drill
records have been quoted, showing that beyond a certain depth
*Cfi. Richardson, op. cit., p. 376.
2See Joseph Barrell, “The Upper Devonian Delta of the Appalachian Geo-
syncline,” Am. Jour. Sci., 4th Ser., XXXVI (1913), 437 ff.
168 C. W. TOMLINSON
below the surface the rocks are no longer red. S.F. Emmons states,
respecting the Maroon formation of the Tenmile district, Colorado,"
that ‘‘in depth, as shown in underground workings, the red color
generally gives way to a greenish gray.’ In another paragraph of
the same folio, Emmons states that igneous or hot-water alteration
destroys the red color. Inasmuch as the ores of this district are
related intimately to igneous and hot-water action, it is natural
to suppose that mine workings would be the most likely of all
places in which to find such effects. The relation here described
is probably a local and abnormal phenomenon.
In his description of the sedimentary rocks of the Anthracite
and Crested Butte quadrangles, where the general situation is
similar to that in the near-by Tenmile district, Eldridge’ states that
“the upper division [of the Maroon conglomerate] is of a peculiar
red or chocolate color, except in regions of local metamorphism”’
of the kind mentioned also by Emmons.
Drilling explorations in the oil regions of Oklahoma and Texas
recently have given us some additional information on the behavior
of the color with depth. Gould? tells of a well some 3,300 feet deep
in southeastern Oklahoma, in which ‘‘the last of the typical Red
Beds was encountered”’ at a depth greater than’ 2,000 feet. The
underlying strata were dull-colored sediments like those outcropping
along the eastern (lower) margin of the Red Beds. Nowhere does
he mention any change in color due to depth. °
A well sunk 3,095 feet at Ashland, Wisconsin, passed through
typical red sandstones of the Lake Superior group all the way,
without any suggestion of a change in color with depth.‘
It is to be remembered that most of the western Red Beds
series are not colored uniformly throughout, but include many
lighter-colored strata; and that many of the Red Beds successions
include gray and green members. Any drill cutting through such
a series would find, of course, changes in color with depth, but they
would not be progressive, and they would have no causal connection
with depth whatsoever.
OPN Gis 2 Op. cit.
3C. N. Gould, “Petroleum in the Red Beds,” Economic Geology, VIII (1913),
768-80.
4 Data from F. T. Thwaites, op. cit.
THE ORIGIN OF RED BEDS 169
This variegation itself constitutes one of the most unanswerable
arguments against weathering in the present cycle as the cause of
the red color. The distribution of gray and green beds among the
red does not appear to have any definite relation to coarseness of
grain, as in the case of intensity of the red color, nor to any other
single stratigraphic feature; and it certainly bears no constant
relation to the topographic surface.
Origin of mottling —The green spots present in some otherwise
red strata have been explained, on the hypothesis that the red
color is due to recent oxidation in weathering, as remnants of the
original color of the beds; but, as will be shown presently, it is
much better in accordance with fact to explain them as spots in
originally red sediments, deoxidized by the agency of some particle
of organic matter which was present in the original sediment.
Dale? discusses the origin of the green spots in red and purple
slates in part as follows:
The difference in color from the green to purple to red is manifestly due to
the differences in the amount of hematite. [See analyses, p. 160.] The green
fossil impressions in purple slate may throw some light on the origin of these
spots. In this case the effect of organic matter, whether the carbonaceous
matter of the lining of an annelid boring or from a marine alga, has been to
diminish the quantity of Fe.O, in the slate. The increase of the carbonates
may be directly connected with the production of CO, by decaying organisms
and the consequent decrease of the Fe.O;. In view of all these facts and indica-
tions, the spots may be safely regarded as probably produced by chemical
changes consequent upon the decay of organisms.
The same conclusion is reached by Miller with respect to green
spots in the red Vernon shale (Silurian, central New York). Miller’
finds dark organic centers in many of the spots, and attributes the
color of green shales associated with the red strata to more abundant
dissemination of organic matter.
It is probable that a very small quantity of organic matter may
reduce or prevent the oxidation of a considerable amount of iron.
The ferruginous matter necessary to stain a sediment is so small in
amount that the quantity of organic matter necessary to accom-
plish the reduction of a patch less than an inch in diameter, like
«T. N. Dale, The Slate Belt of Eastern New York and Western Vermont, Ann.
Rept. U.S. Geol. Survey No. 19, 1899, Part 3.
2 Op. cit.
170 C. W. TOMLINSON
most of the green spots in Red Beds, is so small that it could easily
be effaced or removed. A tiny fragment of vegetable fiber or the
remains of a few minute organisms of any kind probably would
suffice.
Cause of gray and green bands in red beds: Barrell’s hy pothesis.—
Barrell’ states that in the Catskill formation of eastern Penn-
sylvania gray and green colors are typical of sandstones, and red
colors of shales. He therefore suggests a causal relation between
coarseness of grain and condition of the iron content, as follows:
These relations show that there was a tendency toward deoxidation during
the formation of the beds of sand, of oxidation during the deposition of the
Catskill muds. Where the clay and iron oxide were sparing in quantity, the
deoxidation was effective. The conditions which accompanied the deposition
of clay and iron oxide also permitted oxidation to dominate over deoxidation.?
The lack of oxidation of the iron in the sandstones, in spite of its lesser
quantity, suggests that more abundant ground-waters in the sands may have
kept out the air and permitted the organic matter to accomplish its effects, or
perhaps that here the ratio of organic matter was in excess of the ferric oxide.s
A few rare carbonaceous streaks have been observed in the Catskill and
the plant impressions are in places found in deoxidized shales. Coaly and
pyritiferous plant fossils are also preserved in some of the olive sandstones.4
No actual remnants of organic matter are reported to have been
found in red strata, though markings interpreted by Barrell as
rootlet marks are noted by him in certain horizons of red shales.
That physical Conditions of deposition alone should have favored
oxidation in the finer-grained sediments and retarded it in the
coarser seems highly improbable. Where meteoric water moves
most freely, there the most oxygen is carried in solution. The more
rapid the circulation of ground-waters, the more effective are those
waters as oxidizing agents, instead of vice versa, as suggested by
Barrell.
For the lesser quantity of iron in the sandstones we already
have offered an explanatory hypothesis (p. 164). The smaller the
amount of ferric oxide present in a sediment, the smaller, of course,
is the amount of organic matter necessary to bring about its reduc-
tion—or the reduction of a sufficient part of it to mask the color of
the remainder. If organic matter were distributed equally among
T Op. cit. 2 Tbid., p. 458. 3 Tbid., p. 460. 4 Ibid.
THE ORIGIN OF RED BEDS 17/1
all the sediments of the series, it would cause gray and green colors
in the sands rather than in the muds, by reason of the mechancial
concentration of ferric oxide in the latter. The ratio of ferruginous
materials to organic matter seems to be the dominating factor in
determining the colors of ferruginous beds. Barrell’s second
suggestion in the foregoing quotation, dealing with this point,
deserves more careful investigation.
Much of the organic matter carried as sediment in surface
waters tends to be concentrated with the muds, for reasons analo-
gous to those already suggested in the case of ferruginous material
(i.e., fine division); but the proportion so concentrated is probably
smaller in the case of organic matter than in that of ferruginous
material, because of the indiscriminate distribution of driftwood,
the growth of vegetation in most regions of clastic deposition, and
other similar factors. In any of these cases organic matter in
large quantities may enter into the composition of sands and muds
alike, and thus bring about a higher ratio of organic to ferruginous
matter in the sands than in the muds.
These controlling factors are so complex that no constant rela-
tion between coarseness of grain and distribution of organic matter
is to be expected. It is evident from the quotations on p. 170 that
definite organic remains in the section there under consideration are
confined chiefly to gray and green strata; and it is also evident
that such strata include both shales and sandstones. An examina-
tion of the detailed section! of the Catskill formation published by
Barrell in this paper reveals a somewhat less uniform relation
between coarseness of grain and color of beds than one would
understand to be the case from reading the text or the labels on
the graphic columnar section. Of the 3,864 feet of beds definitely
described as of one or the other type, 2,179 feet (56.4 per cent)
bear out Barrell’s generalization that gray and green colors are
typical of sandstones and red colors of shales, gor feet (23.3 per
cent) are noncommittal, and 754 feet (20.3 per cent) are in opposi-
tion to the rule. This variability is in better accord with the com-
plexity of the factors controlling the distribution of organic matter
in sediments than a more constant relation would be; and suggests
t Barrell, op. cit., pp. 451-50. 2 [bid., p. 457-
11s C. W. TOMLINSON
that even here the distribution of organic matter may be a con-
trolling influence in determining the colors of the individual strata.
Dawson,’ in discussing the Triassic (?) Red Beds of Nova
Scotia, says of the gray sandstones and shales interstratified with
them, that ‘‘where thick, they always contain either fossil plants,
bituminous matter or thin seams of coal, or all of these. The fol-
lowing sentence from Geikie,? relative to the Old Red Standsone of
the British Isles, is also interesting in this connection: ‘‘It may be
observed also that where gray shales occur intercalated among the
red sandstones and conglomerates they are often full of plant
remains, and may contain also ichthyolites and other fossils which
are usually absent from the coarser red sediments.”’
Organic matter the controlling influence in the case of the western
Red Beds.—Nowhere in the literature on the western Red Beds is
there suggested such a definite and relatively constant association
of green and gray colors with sandstones, and of red with shales,
as that which Barrell sees in the Catskill formation, and as that
which is described as occurring in the Siwalik formation of India.’
In the foregoing quotation from Geikie, the opposite relation is
implied in the Old Red Sandstone series of Great Britain. In the
Red Beds of the western United States variegation is perhaps more
common in shales than in sandstones, though it occurs to a marked
extent in both. The distribution of gray and green colors in
the Red Beds coincides very closely with the distribution of organic
remains in the same series, in so far as such remains are present;
and this close association, together with the chemical probabilities
of the case, suggest that organic remains now obliterated explain
at least the greater part of the remaining gray and green areas and
strata. The decolorization of these sediments may, therefore,
have been complete before their burial under later strata. The
«J. W. Dawson, ‘‘On the Colouring Matter of Red Sandstones and of Greyish
and White Beds Associated with Them,” Quar. Jour. Geol. Soc. London, V (1848),
25-30. Quotation from p. 26.
2 Geikie, op. cit., p. 1003.
3 Medlicott and Blanford, A Manual of the Geology of India, II (1879), 524-26.
Quoted by Barrell, op. cit., pp. 463-64.
4 Cf. Permian of the Pecos Valley and of the Zuni and Colorado plateaus; and
the Jura-Trias Painted Desert sandstone of the latter plateau.
THE ORIGIN OF RED BEDS 173
occurrence of traces of organic matter in red strata may be explained
by an unusually high content of ferric oxide in those strata, or by
later reoxidation of iron at one time in the ferrous state. The fact
that much the greater part of the occurrences of colors characteristic
of ferrous compounds are in distinct beds with definite boundaries,
indistinguishable in most other characteristics from other beds
which are not so colored, is good evidence that this distribution oi
ferrous and ferric compounds, or of the substances.responsible for —
these compounds, was accomplished for the most part at the time of
sedimentation. It is well to remember that the gray and greenish
strata are very subordinate in the Red Beds of the western United
States.
The general conclusion to be drawn from the preceding dis-
cussion is that there has been in the western Red Beds no extensive
change of ferrous to ferric iron, or vice versa, since the time of
sedimentation; and also that the original distribution of these
compounds in the series was influenced most largely by the dis-
tribution of organic matter.
Variations in hydration of ferric oxide.—That various degrees of
hydration exist in the ferric oxide of the Red Beds today is clear
from the variety of red, brown, and yellow hues which appear
in some members of the group. The major part of the ferric oxide
in the Red Beds is no doubt but poorly hydrated.’ The bright-
and deep-red and red-brown colors (which are most common in the
western series) may be attributed to hematite (anhydrous Fe.O;)
or to turgite (2Fe.0;-H.O). The lighter browns, yellow-browns,
and yellow tints are referable to gothite (Fe,0O;-H.O) or limonite
(2Fe,0;-3H.O), or possibly in some cases even to xanthosiderite
(Fe.O,- 2H.0).
The freer passage of water through the sandstones as com-
pared with the shales makes the constituents of the former, after
consolidation, more susceptible of hydration than those of the
latter. It is entirely probable that in some cases at least this factor
of porosity heightens the contrast in color between coarse and fine
sediments; but it apparently has not affected the greater part of the
Red Beds, in which the ferric oxide is relatively anhydrous. Van
Cf, Richardson’s investigation, discussed on p. 166.
174 C. W. TOMLINSON
Bemmelen has shown that chemically prepared ferric hydrate,
after being partially dehydrated, if placed in a medium saturated
with water vapor, at ordinary temperature, takes up again part of
the lost water.t. Brescius went so far as to say that “when nearly
dry, ferric hydrate has almost as great a tendency to take up water
as oil of vitriol itself.’”” This does not appear to be true, however,
of hematite found in nature. Once completely dehydrated, ferric
oxide becomes a stable compound.
It remains to inquire into the means by which dehydration of
the more hydrous compounds might have been accomplished to
produce the low hydrates, in case these were not originally in the
same condition. The first agent of dehydration which presents
itself is that of heat. Elsden makes the following statement:
The influence of temperature and moisture upon the iron hydrates is well
known. In the case of laterite in India, the yellow xanthosiderite soon weathers
to reddish-brown turgite, owing to dehydration. In the hot and arid regions
ot South California the soils are dark red in colour, the iron being in the form
of hematite instead of the hydrous forms, géthite or limonite. Dehydration
also takes place in the hot regions of the Southern Appalachians, where the air
is comparatively humid. It is only the deeper portions of the soil which retain
the iron in a hydrated form.
In all of the above mentioned cases, the source of the heat which
produces the reaction in question is the sun’s rays. Its action in
the soils is limited to a superficial stratum rarely more than 15 feet
in maximum depth.? Obviously, the direct influence of insolation
cannot be responsible for any extensive dehydration in the Red
Beds, whose characteristic colors are known to extend to depths of
more than 2,000 feet.
«J. M. Van Bemmelen, “Sur le colloide de oxyde ferrique,” Recueil des travaux
chimiques des Pays-Bas et de la Belgique, VIL (1888), 112.
>
2E. Brescius, ‘Researches on Ferric hydrate,” abstract in Jour. Chem. Soc.
London, XXIV (1871), 407.
3 J. V. Elsden, Principles of Chemical Geology (London: Whittaker & Co., 1910),
Pp. 97.
4W. O. Crosby, ‘‘On the Contrast in Color of the Soils of High and Low Lati-
tudes,” Amer. Geologist, VIII (1891), 74; E. A. Smith, Geol. Survey of Alabama, Reft.
Jor the Years r88r and 1882, p. 186.
5 See p. 168.
THE ORIGIN OF RED BEDS 175
Another source of heat which might be suggested is that of
igneous intrusions. The absence of igneous rocks in the greater
part of the western Red Beds, including the regions where drilling
has shown the colors to be unchanged at depth, proves that this has
not been a factor of widespread importance. Heat due to regional
metamorphism or to structural deformation of any sort must like-
wise be discredited here, as the Red Beds are substantially flat-
lying over vast areas, and are nowhere intensely deformed or
metamorphosed, except locally in the immediate neighborhood of
igneous bodies.t That compression due to the weight of overlying
sediments may have created sufficient heat for the accomplishment
of extensive dehydration must be recognized as a possibility,
although in many areas where the Red Beds occur the requisite
overlying sediments are not known ever to have existed, and the
uppermost members of the series in these localities are as brilliantly
red as any below them. Furthermore, pressure creates heat only
by the performance of mechanical work, and microscopic study of
the Red Beds reveals no evidence of internal deformation.
Crosby’ concludes that the process of dehydration of ferric oxide
is largely a spontaneous one, which goes on independently of any
outside influence whatsoever, though aided by high temperatures.
He states as evidence in support of this hypothesis that the red
sedimentary formations and the red iron ores of the world occur in
the older systems chiefly, while in the younger systems ferruginous
formations and ores are commonly yellow. ‘There are, however,
many exceptions to this rule, such as the buff Cambrian sandstones
of the Mississippi Valley, the modern red residual iron ores of Cuba,
and the dark-red hematitic bog ores in Sweden and elsewhere; and
furthermore, the dehydration of the pre-Cambrian red sandstones
and argillites may be attributed in some cases partly to regional
metamorphism, which has not affected the younger beds.
Richardson; has given much weight to this “essentially spon-
taneous’” process. He states that ‘‘the dehydration of ferric
hydrates tends to go on under ordinary conditions without any
unusual cause.”? ‘This has been repeatedly demonstrated by
experiment.’”’> But none of the experimenters to whom Richardson
t See p. 168. 2 Op. cit. 3 Op. cit., Pp. 392. 4 [bid. 5 [bid.
176 C. W. TOMLINSON
‘
refers' appears to have considered the observed dehydration as
truly ‘‘spontaneous”’; and certainly they have shown the process
to be closely dependent upon external conditions. The chemically
precipitated colloidal ferric hydrates possess, when first formed, a
higher content of water than any of the forms known to occur as
minerals. According to Van Bemmelen,? on standing in a dry
medium at ordinary temperatures these colloids gradually approach
the composition 2Fe,0;-H.,0, beyond which the percentage of
combined water is not reduced without the application of much
higher temperatures. Under water, or in air of moderate humidity,
they have not been shown to lose water beyond the composition
Fe.O;- 2H.O except at temperatures above 50° C.,3 and heating at
50-60° C. for 2,000 hours failed to bring about dehydration beyond
the composition 2Fe,0;-H.O0.4. Temperatures as high as these
cannot be assumed to have existed, except locally, in the Red Beds
sediments since burial. The so-called spontaneous dehydration
observed in the laboratory is probably subject to the terms of Van
Bemmelen’s conclusion: ‘‘The red-brown substance, which has
been considered to be a hydrate, is a colloid . . . . which has no
stable composition; it maintains an equilibrium with the tension of
the water vapour in the surrounding medium.’’> Since burial, the
great mass of the Red Beds sediments, except in the most arid dis-
tricts of the West, have been saturated with ground-water, a con-
dition decidedly unfavorable to dehydration at the temperatures
there existing.
Yet another agent of dehydration is mentioned by Elsden:
The presence of any substance in solution which lowers the vapour tension
of water will lower the inversion temperature of gypsum. ... . Even solid
‘J. M. Van Bemmelen, ‘‘Sur le colloide de l’oxyde ferrique,” Recueil des travaux
chimiques des Pays-Bas et de la Belgique, VII (1888),106-14; Edward Davies, ‘“ Action
of Heat on Ferric Hydrate in Presence of Water,’ Jour. Chem. Soc. London, XIX
(1866), 69-72; G. C. Wittstein, ‘Uber das Verhalten des Eisenoxyhydrates unter
Wasser,” Vierteljahreschrift fiir praktische Pharmacie, I. Band (1852), 275-76.
? Op. cit., pp. I10-11. :
’T. Carnelly and James Walker, ‘‘The Dehydration of Metallic Hydroxides by
Heat,” Jour. Chem. Soc. London, LUI (1888), 89; D. Tommasi, ‘“ Ferric Hydrates,”’
abstract in Jour. Chem. Soc. London, XLIV (1883), 24.
4 Davies, op. cit., p. 70.
5 Van Bemmelen, of. cit., p. 114. Translated from the French.
THE ORIGIN OF RED BEDS 177
gypsum ... . can be changed into anhydrite by a concentrated solution of
sodium chloride. ... . These facts are of interest as pointing to the possibility
of dehydration of minerals in rocks, in contact with salt solutions, at a tempera-
ture considerably below their normal inversion point.!
. .. . The occurrence of red ferruginous sandstone in conjunction with
layers containing brown hydrated ferric oxide is less readily explained [than
the superficial dehydration of soils, mentioned in the quotation on p. 174, supra],
but the dehydration of certain beds may have been effected by contact with
salt solutions, as in the case of gypsum already referred to above.”
Dehydration by contact with salt solutions presumably would
affect the more porous beds first; whereas in the western Red Beds,
as already described,’ it is generally in the more porous beds that
the lighter colors occur, and the shales are in general of deeper hue
than the sandstones. Just how far the action of salt solutions may
have been effective, both during and since sedimentation, in accom-
plishing dehydration in the neighborhood of such saline deposits as
occur in the Red Beds, it would be difficult to say; but for the group
as a whole it appears that this agency cannot have been of general
importance.
In summation, it may be said that while widespread dehydration
of iron oxide in the Red Beds since sedimentation cannot, at present,
be proved not to have taken place, the greater weight of evidence
now at hand is opposed to it; that the opposite process, hydration,
may well have been active in the more pervious beds of the series;
and that, therefore, the probabilities are quite as much in favor of a
lower degree as of a higher degree of hydration, on the average, in
the Red Beds at the time of sedimentation than at present.
WAS THE COLORING MATTER A CHEMICAL OR A
MECHANICAL SEDIMENT ?
Having determined as nearly as the available evidence permits
the condition of the coloring matter of the Red Beds at the time of
their deposition, we may proceed to inquire as to the geographic
conditions which gave rise to sediments so colored. The. first
t Elsden, op. cit., pp. 85-86. See also H. Stremme, “‘Zur Kenntnis der wasser-
haltigen und wasserfreien Eisenoxydbildungen in den Sedimentgesteinen,” Zeit. fiir
prakt. Geol., January, 1910, pp. 18-23.
2 Elsden, op. cit.? p. 97. P. 158-50.
178 C. W. TOMLINSON
question to be answered in this connection is: Was the ferruginous
matter deposited as a mechanical or as a chemical sediment ?
The general absence of coloring matter from the non-clastic
members," which are in very large part inorganic chemical precipi-
tates, indicates quite clearly that the conditions favoring free
chemical deposition of calcium and magnesium carbonate or of
calcium sulphate were not those under which the coloring matter
was usually deposited. The close limitation of ferruginous material
to the clastic sediments proves that the conditions under which
clastic sedimentation took place favored the deposition of iron
oxide also, and strongly suggests that that material itself was carried
and deposited as a mechanical sediment, for the most part at least.
In this connection it is of interest to note that Dawson? drew a
similar conclusion as early as 1848 with reference to the contrast in
color between the clastic and non-clastic strata of the Red Beds
of Nova Scotia.
The condition of the ferric oxide in the Red Beds sediments, as
revealed by the microscope, is one of very fine division. Since fine
division is to be expected from the mode of origin of the ferric oxide
in soils,’ this cannot be taken as evidence that it is a chemical pre-
cipitate, in place, in the rocks. If it were the latter, definite orien-
tation of crystals of hematite with respect to peripheries of grains
might be looked for. I never have seen this phenomenon in thin
sections of Red Beds sediments. The microscopic evidence is
therefore rather noncommittal as regards the present question.
The processes of weathering leave much the greater part of the
iron content of all types of rock as a residue in the soil, subject to
mechanical transportation. All of the other common chemical
constituents of rock, with the probable exception of alumina, are
leached from the soil more rapidly than ferric iron. The scarcity
of iron in any form in the surface waters of the continents, abun-
dantly shown by the analyses of lake and river water published by
Clarke, and its even greater scarcity in the ocean,’ testify to the
~See p. 157. 2 Op. cit. 3See p. 164.
4F. W. Clarke, “‘The Data of Geochemistry,” 2d ed., Bull. U.S. Geol. Survey
No. 491, 1911, chap. iii.
8 Ibid., chap. iv.
THE ORIGIN OF RED BEDS 179
fact that chemical deposition of salts of iron is only exceptionally
an important process in earth metamorphism. Glauconite, the
most common of such deposits at the present time, is of such
peculiar nature as to be readily recognized where it occurs in older
sediments: it certainly is not involved to any appreciable extent in
the origin of the Red Beds. Bog iron ore, the only other common
type of ferruginous chemical precipitate at present, is connected
intimately, in origin, with abundance of vegetation and with
peculiar and limited topographic conditions; and although deposits
of this type are scattered over many parts of the world, none of them
is comparable in extent or in thickness to even the smallest of
the Red Beds areas. Furthermore, no deposits similar in textural
character to bog ores are known in the western Red Beds.
In view of the facts above stated, it seems a safe conclusion
that the coloring matter of the Red Beds was transported and
deposited almost if not quite wholly as a mechanical sediment;
and, therefore, without danger of serious error, we may limit
investigations of possible conditions of origin of this coloring matter
to those which would produce it as a mechanical sediment purely.
This applies to the gray and green members of the Red Beds series
as well as to those in which the iron is present chiefly as ferric oxide;
for if the ferrous iron in the former be explained as the result of the
action of organic matter deposited in those strata,’ the ferruginous
matter may have been in the ferric form during transportation,
quite as well as in any other.
= SEO oh 27C—72-
[To be continued]
STUDIES IN HYDROTHERMAL ALTERATION
PART I. THE ACTION OF CERTAIN ALKALINE SOLUTIONS ON
FELDSPARS AND HORNBLENDE
EK. A. STEPHENSON
University of Chicago
In the study of ore deposits from a genetic standpoint the
subject of attendant wall-rock alteration has received deserved at-
tention from geologists. Profound changes of a chemical and min-
eralogical character have been recorded at many places, and the
relation existing between the various types of wall-rock alteration
accompanying ore deposition led to the suggestion that a knowledge
of the conditions which bring about such alteration would throw
great light on the problem of ore genesis. The data obtained in
regard to the temperatures, pressures, and nature of solutions would
also be of value in interpreting the geologic history of such occur-
rences.
The most important of these alteration minerals are kaolin,
sericite, and chlorite, and the knowledge concerning their origin is
chiefly confined at present to speculations based on their modes of
occurrence and their associated minerals. There is especially great
difference of opinion’ as to the origin of kaolin. By some writers
kaolinitic alteration is attributed to the action of meteoric waters
rich in carbonic acid, by others to meteoric waters which have made
a cycle of underground courses, and by still others to the emanations
from a cooling magma while these are possibly yet in a gaseous
state. In regard to sericite and chlorite associated with ore bodies
there is nearly general agreement that these have been formed by
the action of the solutions which deposited the primary minerals,
whether these solutions be magmatic or meteoric, upon the feld-
t Bibliographies of the literature on kaolin are given by Résler, Neues Jahrb.,
Beil. Bd. XV (1902), 231, and by Lazarevic, Zeit. prakt. Geol., XXI (1913), 345. An
introduction to a discussion of the origin of kaolin was initiated by Lindgren, Econ.
Geol., January, 1915.
180
STUDIES IN HYDROTHERMAL ALTERATION 181
spars and the ferromagnesian minerals. Calcite and quartz are
also prominent products of these reactions. Further, the relations
of these minerals to the ores indicate that the processes of altera-
tion and ore deposition have gone on contemporaneously. This is
shown by the progressive decrease in the intensity of the alteration
laterally from the veins, and by changes in the character of the
alteration in the same direction. For example, the following
extract from the report by F. L. Ransome! on the “Economic
Geology of the Silverton Quadrangle”’ illustrates these points.
At points 150 feet east of the lode the country rock is fine-grained and
faintly mottled, showing only a few pale phenocrysts of feldspar and an occa-
sional tiny grain of quartz. Under the microscope the rock reveals the char-
acter of a much-altered andesitic tuff or fine breccia. The feldspars have been
completely altered to aggregates of sericite and calcite, while areas of calcite
and chlorite probably represent former phenocrysts of augite. The ground-
mass is a rather indistinct aggregate of secondary quartz, sericite, and chlorite
with a little apatite and rutile. The rock is wholly recrystallized into a sec-
ondary aggregate while retaining the gross structure of the original.
At a distance of 100 feet from the vein the . . . . chlorite and calcite are
abundant, but much of the plagioclase is still recognizable. Sericite and
quartz are not such prominent constituents. ... .
At 50 feet from the vein .... the feldspar phenocrysts have been
changed to aggregates of calcite and sericite, while areas of chlorite and calcite
with sometimes rutile are all that remain of the phenocrysts of augite or
biotite. The groundmass also, while preserving the outlines and in small part
the substance of former lath-shaped feldspars, is now an aggregate consisting
chiefly of quartz, chlorite, sericite, and a little rutile and apatite. ....
At 2 feet from the vein .. . . it is seen that alteration has been more
thoroughen) oy.) The forms of the phenocrysts are preserved by pseudomor-
phous aggregates of sericite with some chlorite, calcite, and rutile apparently
after biotite, and quartz, sericite, and chlorite in varying proportions after
augite and plagioclase. The groundmass is entirely recrystallized . . . . and
the dominant minerals are quartz and sericite.
A specimen taken from the wall of the vein showed more evident alteration
. . and the rock is wholly recrystallized. The former phenocrysts of feld-
spar are replaced by pseudomorphus aggregates‘of quartz and sericite. ....
Of the augite no trace remains, but some sericite inclosing rutile is apparently
pseudomorphous after biotite. The groundmass is a finely crystalline mosaic
of quartz and sericite. The notable feature of this wall rock is the absence
of calcite and chlorite. ....
tF. L. Ransome, Bull. 182, U.S. Geol. Survey, pp. 116-18.
182 E. A. STEPHENSON
To sum up then, the alteration involves the change of the feldspars to
sericite, calcite, and quartz; of augite to calcite and chlorite; and of biotite
to chlorite, sericite, and rutile.
Chloritic alteration appears to precede sericitic alteration and
to require less intense or less prolonged action or solutions of a
different character, so that sericite is found closer to the veins than
chlorite, and chlorite dominates farther from the veins. It may be
in place here to note that many consider the solutions which ema-
nate from the magma in its final stages acidic in character while
others hold that they are alkaline. A study of volcanic gases and
of the sublimates present in craters indicates that the volcanic
vapors are quite certainly acid, and Day and Shepherd’ found that
the magmatic waters which they collected from the small dome
within the crater at Kilauea were acid. However, to conceive of
these solutions as remaining acid for a long journey through rock
masses after their escape from the magma requires a high degree
of acidity, and geologists have been loath to accept such a view.
It is clear then that the experimental formation of these altera-
tion products from the feldspars and ferromagnesian minerals will
give some clew as to the nature of the solutions and the tempera-
ture and pressure conditions that obtained during the deposition of
the associated primary ore bodies. NaAlISi,0¢,H,O+Si0O.+Na’.
The analcite was identified optically and also by sifting out the ~
unchanged feldspar with its adhering analcite, gelatinizing the
remaining crystals with hydrochloric acid, and allowing a small
portion of the solution to crystallize out under the microscope as
sodium chloride; the remaining portion of the solution was tested
for alumina with ammonia water. After drying at 110° C., the
crystals yielded water in a closed tube.
Group IIT: Sodium carbonate solutions on hornblende.—A series
of experiments, Nos. 11, 12, and 13, exactly like those in Group I,
were then tried with hornblende as the mineral (Table III). In no
TABLE III
|
Mineral Time Solution Concen: Vol. Sol. Nob Temp. ies Results
aa Tees este) |
.| Hornblendel3 yrs. 1 mo.| NazCO;| N/2 |1,200 c.c.|...... a (C5 ae 1 | Nochange
c 9o days : e BOOe Hlniacee Loon |G: wy
« 82 t s 60 85 c.c.|183° II ‘
192 E. A. STEPHENSON
case did there appear, under the microscope, to be any change.
No gelatinous silica separated from the solutions after long standing.
Group IV: Potassium fluoride solutions on feldspars and horn-
blende.—F luorine has long been looked upon as one of nature’s
important mineralizers;' it occurs in small quantities in the emana-
tions from Kilauea,? is abundant as fluorite in metalliferous veins, is
a constituent of many minerals such as apatite, amblygonite, lepi-
dolite, topaz, and cryolite, and is considered by Spurr? an essential
constituent of muscovite. Table IV shows the experiments con-
TABLE IV
No.| Mineral Ti Solution |CPS™Iyo1. Sol] VO | oT ues. Result
No. era | ime olution |} pation - Sol.) Tube emp. Aton, esults
a |
14..| Adularia 82 days} KF* | N/ro]| 60c.c| 85 c.c.| 183°C.| 311z |No change
Hse c “ 18 “ “ 50 80 233° 30 “ “
16..| Microcline | 18 mes en A Omen 715 233° 30 ~— | Minute rods
17..| Albite 18 Le oC eine | 30 |7o | 233° 30 No change
18..| Hornblende) 82 Femara tA &) 60 SSaeEOse 11 | Brown iron oxide
iQ z 55 283 30
15 | ESO = Tube burst
|
* This salt contained a small amount of the acid salt HKF:2.
ducted with potassium fluoride. In experiments Nos. 14, 15, 16,
and 17 the feldspars showed no change other than a possible slight
etching. In No. 16 there appeared some minute bacteria-like rods
that were not further identifiable. In No. 18 the hornblende was
vigorously attacked. The product is an amorphous brown mass
resembling limonite and consisting of hydrated iron oxide together
with grains of partially altered mineral. Some of these grains are
bleached to isotropic transparency, others have a rim of isotropic
matter surrounding ellipsoidal grains in the interior. No gelatinous
precipitate appeared in the decanted solution on standing in paraffin
lined bottles for several months. In No. 19 the tube burst and the
mineral appeared unchanged.
Group V: Mixtures of carbonate and fluoride solutions on feldspars
and hornblende.—Since the feldspars were not visibly attacked by
the fluoride solutions but had been attacked by the alkaline carbo-
™See especially C. Doelter, Allgem. chem. Min., p. 207, and W. Bruhns, Neues
Jahrb. Min. Geol., II (1889), p. 26.
2A.L. Day and E. S. Shepherd, Bull. Geol. Soc. Am., XXIV, 592.
3 J. E. Spurr, Professional Paper 42, U.S. Geol. Survey, p. 233.
STUDIES IN HYDROTHERMAL ALTERATION
1)5)
nate solutions, it was deemed advisable to try a mixture of the two
solutions to see if the traces of fluoride present would modify the
results in any way (Table V).
The feldspars in Nos. 20, 21, and 22
No.
DOM
Die g
DP 0
RE
24..
r
DS
20).
DG
DSi
ZO
30..
Bite
TABLE V
Mineral Time Solution Concentration |Vol. Sol.
Adularia | 90 days) NazCO,;+KF) N/2+N/r10|300c.c
“ 4 I “ “ “ (3 54
“ 82 “ « “ « Es
« 18 « « « « 16
« Is « « « « 65
Orthoclase | 15 “ “ « « 50
Microcline |} 18 “« « « « 48
Albite 18 “ « « « 48
Hornblende go “ “ “ « 300
Bus 41 « « « « 60
“ 8 2 “ (3 “ “ 60
e 3 “ « “ “ 60
Ae. Temp.
apt la ae too C.
80c.c.|183°
Som |n8an
85)" |233,
100. = |280"
100. = |280°
LOOM al2sem
Sommlescn
sre 100°
Soo alr8az
85 183°
Som |235u
Press.
Atm.
30
I
It
It
30
Results
No change
“ “
“ “
Analcite
Needles
Twins of
unknown
mineral,
also
needles
No positive
change
Analcite
No change
¢
were not visibly attacked and the decanted solutions gave no pre-
cipitate on standing. No. 23 showed crystals of analcite. No. 24
showed some needles with parallel, or
nearly parallel, extinction and pos-
sibly some isotropic forms, though
these were not positively identified.
No. 25 contained many needles like
those in No. 24 with no analcite.
These needles have an extinction
angle of less than 2°; index in the
direction of elongation is 1.490, and
at right angles to this 1.517; elonga-
tion is negative. The crystals after
drying at 110° C. yield no water in a
closed tube. Good terminations at
both ends are common. No. 25 also
Fic. 7.—Twinned crystals pro-
duced by experiment No. 25.
contained beautifully twinned crystals, illustrated in the accom
panying sketch (Fig. 7) made with a camera lucida. The crystals
194 E. A. STEPHENSON
are perfectly transparent, have an index close to but greater than
1.565, an extinction angle of 43°, and are probably monoclinic. In
experiment No. 26 no evidence of any change appeared. In experi-
ment No. 27 icositetrahedra of analcite appeared, some free and
some including fragments of the feldspar. The hornblende in all
of this group of experiments was unchanged. It is concluded that
the presence of the fluoride had practically no influence upon the
alteration.
Group VI: Sodium bicarbonate solution upon feldspars and
hornblende.—These experiments embody an attempt to increase the
pressure both by raising the temperature and by increasing the
concentration of the carbon dioxide through dissociation of bicar-
bonates (Table VI). In experiment No. 32 scarcely any feldspar
TABLE VI
Concen- Vol. Sol. Vol
No Mineral | Time Solution peatinn Tube Temp. eae Results
32..| Adularia 15 days NaHCO, N/2 | 45 c.c.| 85 c.c.| 233°C.| 30 | Analcite
Boer “ iis . Selso. 85 280° 65 é
34. .| Albite 15 & sn ic 85 2335 30 | Analcite and
needles
aie _ 5 A KOO") ss 280° 65 | Tube burst, but
needles formed
36..| Hornblende 15 £ eg 85 233° 30 | No change
« 15 “ “ 45 85 280° 65 “ «
remained and much analcite appeared as free crystals and as aggre-
gates. Gelatinous silica appeared in the decanted solutions after
some time. Similar results with decided etching of the feldspar
grains appeared in No. 33 where the pressure was practically
doubled. Possibly less analcite formed in this than in the previous
experiment at the lower temperature. In No. 34 with albite, anal-
cite also formed with many needles like those in experiment No. 25,
Table V. In experiment No. 35 the tube burst where poorly sealed,
but the mineral was nearly all altered to needles as in experiments
Nos. 24, 25 and 34. These were analyzed qualitatively and found to
consist of soda, alumina, and silica and yielded no water in a closed
tube. The writer was not able to find any natural sodium alumi-
num silicate whose properties agree with these. Needles having
STUDIES IN HYDROTHERMAL ALTERATION 195
the same optical properties as these also appeared in experiment
No. 46 and are undoubtedly the same thing.
The hornblende was unchanged in experiments No. 36 and 37;
the tube in No. 37 burst some time during the course of the heating.
Group VII: Potassium bicarbonate solutions on feldspars and
hornblende-—These are similar to the experiments of Group VI,
except that potassium bicarbonate solutions were substituted for
the sodium bicarbonate solutions (Table VII). In no case either
TABLE VII
Concen- Vol. Sol. Vol. Press.
No Mineral Time Solution aan Tube Temp. Nn. Results
38..| Adularia 15 days) KHCO,| N/2 | 45c¢.c.| 75c.c.| 233°C.| 30 | No change
30. i (73 15 “ “ 50 90 280° 65 (13 “
40. .| Albite 15 FAS 750) \233)0 04 3 Ol | aaraana
HD s 5 Y is 60 =|I05 280° 65 Y -
2..| Hornblende} 15 bs 45‘ |I00 Pyeles 30 be iS
with the soda or potash feldspar or with hornblende did any change
appear in the minerals. The writer is unable to give an adequate
explanation of this fact, but it may have some bearing on the
question whether potash is introduced or not in hydrothermal
processes.
Group VIII: Sodium tetraborate solution upon feldspars and
hornblende-—A few experiments were tried with borax solutions
with results very similar to those produced by the alkali carbonates
(Table VIII). In No. 43 well-formed crystals of analcite as rhom-
TABLE VIII
No. Mineral Time Solution Concent; Vol. Sol. Nel Temp. Eres : Results
43..| Adularia 15 days| Na2B,0,| N/4 | s50c.c.\100c.c.| 233°C.| 30 | Analcite
44..| Albite 15 - i 50 95 233° 30 | No change
45..| Hornblende| 15 g . 50 90 233° 30 ee is
bic dodecahedra appeared. No alterations occurred in the other
experiments.
Group IX: Sodium sulphide solutions upon feldspars and horn-
blende.—The presence of the metallic sulphides indicates that at
196 E. A. STEPHENSON
certain phases of the vein-forming process sulphide solutions must
be present. Though the solutions are undoubtedly very complex,
their efficiency as hydrothermal agents is very probably due to a
few components. The physical state of these solutions has been
recently shown by Tolman and Clark’ to depend decidedly upon the
composition, at least at ordinary temperatures, and it may also
have some decided influence upon the character of the alteration.
In the following experiments the copper tubes were vigorously
attacked and chalcocite crystals lined the walls of the tubes
(Table [X). In No. 46 needles of the anisotropic crystals like those
TABLE IX
No. Mineral Time | Solution
| | | =
Concen -|;; Vol. Press. é
tration Vol. Sol. Tube Temp. Aten Results
.| Adularia 15 days) NaS | N/2 | 5o0c.c./120¢.c.| 233° c.| 30 +| Analcite and
| | needles
..| Albite }) sets ng lea 50. ~=—|100 | 2320 30 | Analcite
.| Hornblende| 15 | - | 50 105 | 23 3° | 30 | No change
obtained in experiments Nos. 25 and 34 were formed, together with
well-formed analcite crystals. Very little of the original feldspar
remained. In No. 47 perfect analcite crystals appeared as icosite-
trahedra and as combinations of the cube and rhombic dodeca-
hedron. These vary in size from one-half to one millimeter in
diameter. The hornblende in experiment No. 48 was not attacked
and no pyrite could be identified in the product. No sulphur was
obtained by heating the mass in a closed tube. The results with
the feldspars are quantitatively greater than in any other experi-
ment; this was probably due to the fact that the hydrogen sulphide
is a weaker acid than is carbonic acid and the hydrolysis therefore
produces a more strongly alkaline solution.
Group X: Aluminate solutions on feldspars and hornblende.—In
the previous experiments the loss of silica from the minerals resulted
in an apparent rise of the alumina content of the new minerals.
With the thought that possibly an increase in the concentration of
the alumina in the solutions might cause the solubility product for
«C. F. Tolman and J. D. Clark, Econ. Geol., TX (1914), 550.
STUDIES IN ‘HYDROTHERMAL ALTERATION 197
compounds richer in alumina to be exceeded, a few experiments
with aluminate solutions were tried. These solutions were pre-
pared by taking a weighed quantity of aluminum sulphate, precipi-
tating the aluminum as hydroxide, washing the precipitate and then
adding it to normal sodium or potassium hydroxide and diluting
TABLE X
Concen-
No. Mineral Time Solution of Kor Vol. Sol. nce Temp. ies: Results
a
49..| Adularia 15 days} Sodium N/2 | 40c.c.| 80c.c.| 280°C.| 65 |Analcite
aluminate
50. S 15 Potassium | “ —| 4o 85 280° 65 |Hexagonal
aluminate plates and
| needles
51..| Orthoclase | 15 Potassium # 60 ~=|120 280° 65 |Hexagonal
aluminate, | plates and
needles
52..| Albite 5 Potassium S 30 70 280° 65 |Hexagonal
aluminate} | plates
53--| Hornblende| 15 Potassium = 35 75 280° 65 |No change
aluminate
one-half. After this had been allowed to stand for several hours it
was filtered from its slight precipitate (Table X). In No. 49 anal-
cite crystals formed, which were identified chemically and micro-
scopically. In Nos. 50, 51, and 52 twinned
hexagonal plates, with anomalous division into
fields under polarized light, resulted, as shown
in Fig. 8. These gelatinize with hydrochloric
acid and contain sodium, but no aluminum could
be detected in them by a microchemical test.
The hornblende was not attacked. Fic. 3—Twinned
Group XI.—Albite and hornblende were hexagonal plate result-
heated for 15 days at 280° C., with saturated Oe
solutions of calcium bicarbonate. The tubes ~~ ’ A
burst in each case and the minerals showed no change.
GEOLOGIC BEARING
Though the alteration of feldspars to analcite has not been com-
monly described, in many cases it is very possible that some of the
198 E. A. STEPHENSON
determinations of isotropic minerals as glass may be incorrect, and
that analcite has been overlooked. In examining the slides in the
University of Chicago collection a slide from a trachyte of Bannber-
scheid, Westerwald, Nassau, was found which showed the soda
feldspars altered to analcite though the original crystal boundaries
remained sharp. The alteration does not follow cleavage cracks
but appears in irregular patches. Mr. K. F. Mather in a forth-
coming paper will describe an eruptive cone of Quaternary age in
the canyon of the Mancos River ten miles southwest of Mancos,
Colorado—locally known as the “ blowout’’—which is cut by dikes
of augite minette. These dikes carry fragments of granite xenoliths
which are deeply corroded and partially assimilated. The feldspars
are altered to analcite—identified microchemically. A careful
study of rock specimens would probably show that this type of
alteration is much more common than has been supposed.
SUMMARY
1. Alkaline solutions of different characters dissolve the feld-
spars with separation of silica and crystallization of compounds less
rich in silica. The solutions are probably hydrolyzed since the
reactions are accelerated by the presence of alkalies, by increased
concentration of the alkalies, and by higher temperatures.
2. Feldspars and hornblende are not appreciably attacked by
pure water at temperatures up to about 300° C. adularia to at least
350 C., showing that the dissolved substances rather than water
alone must cause the differences in the nature of the alterations.
3. Albite and orthoclase feldspar seem to respond to the action
of the alkalies in nearly identical ways, and hence the conclusion
is patent that they have very similar chemical structures.
4. The influence of small amounts of fluoride and borates as
mineralyzers has not been found important, at least in the presence
of the other substances. This leads to the suggestion that possibly
the mineralyzing effect is merely that of causing solution at tem-
peratures where the silicates in question would otherwise be much
less soluble.
5. It is notable that no kaolin or kaolin-like substance forms
from alkaline solutions at temperatures up to 280° C. The sugges-
STUDIES IN HYDROTHERMAL ALTERATION 199
tion seems necessary that since pure water has practically no effect
on the feldspars, and that since the alkaline waters produce minerals
other than kaolin, kaolin probably forms by the action of acid solu-
tions upon the feldspars. The literature bearing on the field occur-
rences of kaolin shows a striking lack of references to association of
carbonates and kaolin, though this would be expected if carbonated
waters are the cause of the formation of kaolin from the feldspars.
6. The general agreement of the data obtained throughout the
range of temperatures used shows that the silicates may be studied
with the apparatus described, up to 300° C., with gratifying results.
and without great mechanical difficulties, and also without the
necessity of contamination from undesirable sources such as glass
tubes.
The writer is indebted to Professor W. H. Emmons for suggest-
ing the problem and to Professor A. D. Brokaw for sincere interest
and many suggestions during the progress of the work. Further
work of a similar sort is in progress and the next paper will deal
with the action of various acid solutions, especially hydrofluoric
acid on the same group of minerals.
ce
ZONAL WEATHERING OF A HORNBLENDE GABBRO
ALBERT D. BROKAW anp LEON P. SMITH
University of Chicago
In connection with a study of the alteration of the so-called trap
or diabase dikes at La Grange, Georgia,’ one of the writers collected
some interesting specimens showing a weathered zone in which the
decomposition is extreme, with an abrupt transition into fresh rock,
practically free from the effects of weathering. ‘This paper is con-
cerned with the description of a typical specimen, and with the
results of chemical analyses of the fresh rock, the partly altered
material, and the extreme phase of alteration present.
La Grange is in the extreme western edge of the state, not many
miles from the southern end of the belt of crystalline rocks which
extends from Maine to Alabama. The country rock is for the most
part gneiss, cut by granitic intrusions. Both gneiss and granite are
cut by pegmatites and basic dikes, the latter usually called diabase,
and supposed to be of Triassic age. At La Grange there is a series
of dikes, only a few feet apart, ranging up to forty feet in width,
with an average of about four to six feet. The dikes have a general
north-south trend, and are abundant over an area of a little more
than half a square mile.
The older crystalline rocks are very deeply weathered. The
basic dikes have been considerably altered at the surface, and in
many instances may be traced by the strong iron stain they have
imparted to the soil. In some excavations, however, material
showing no appreciable effects of weathering may be obtained. In
some case: weathering has been strongly marked along joints,
changing the character of the material for an inch or less, beyond
which the rock is fresh. Fig. 1 shows a specimen in which the zone
of alteration is about an inch thick. Analyses were made of the
tL. P. Smith, Alteration of Diorite by Weathering, Dissertation, University of
Chicago, 1915.
ZONAL WEATHERING OF A HORNBLENDE 201
outside, much-altered portion, and of the part of the weathered zone
adjacent to the fresh material. A specimen from an entirely fresh
portion of the same dike was analyzed for a comparative study.
The fresh rock is finely grained, holocrystalline, nearly black in
color, with small white feldspar crystals evenly distributed through
Fic. t—Specimen showing zone of weathering X2. Circle shows approximately
the part from which the slide shown in Fig. 3 was taken.
the mass, which is dominantly hornblende. Small garnets, irregu-
larly distributed, and small crystals of pyrite are present. Micro-
scopically, the rock is found to consist of hornblende (65 per cent),
which may be secondary, labradorite (32 per cent), with small
amounts of orthoclase and augite, and accessory magnetite, pyrite,
titanite, and apatite. One of the typical slides is shown in Fig. 2.
The rock is a hornblende gabbro. |
ALBERT D. BROKAW AND LEON P. SMITH
to
fe)
iS)
The partly altered material is notably lighter in color than the
fresh rock. Most of the
hornblende has been
weathered, leaving brown
iron stains and a small
amount of chlorite, but
some particles of appar-
ently fresh hornblende
are tobeseen. ‘The feld-
spar has been changed to
a chalky white material
in an iron-stained matrix.
Microscopical study re-
veals some unchanged
hornblende, but for the
most part only alteration
products are discernible.
Fic. 2.—Section of fresh hornblende gabbro 2 : ‘ :
X20. (Two rather large cracks appear as light Limonite, white mica
bands.) Ordinary light. (probably also gibbsite),
chlorite, zoisite, and a
small quantity of mag-
netite make up the mass.
The weathered zone is
sharply set off from the
fresh material even in thin
section, In Figs 92> the
fresh portion is shown on
the left, changing to
altered on the right.
The most completely
weathered portion its a fri-
able, earthy, non-plastic
mass, strongly iron
stained, and so thoroughly
disintegrated that the
- : Frc. 3.—Slide showing transition from fresh to
original texture of the altered portion of specimen. X25. Crossed nicols.
ZONAL WEATHERING OF A HORNBLENDE 203
rock is practically lost. No microscopical study of this material
was undertaken.
The results of chemical analyses, made in duplicate in every case
and in triplicate in a number of determinations, are given in Table I.
The following recognized effects of weathering are well illustrated:
loss of silica, apparent increase in alumina, increase in ferric iron,
decrease in ferrous iron, loss of bases, increase of combined water,
and decrease in specific gravity. The very small development of
carbonates may be due to the fact that most of the available carbon
dioxide has formed soluble bicarbonates in removing lime, mag-
nesia, and alkalies."
TABLE I
r* 2t 3t 1 2t 3r
SIO ee aay ae ASH LOM 20K02) 2334) lMiOsa. = asses .31 .18 gills
AIO; ee ee es 17634 || ASCO |) BAcGO. WIEN 505 aco 47 5 Sit tr
KeOe si osess: Qowy || Wie ss | Dies IlCOhs osotousoc none eI 382
LOO eps aia nis ea G.@0) || AoCe) ||| wen NSoseouaceonec .10 .04 | none
IN OF ale ies! 4.67 3-03 585)
CaO Re eran! 17.50 | 7.96 B75 ee MO talennmense 100.10 |100.23 |100.20
INE aetna A 6X0) |). wg Gy 39
KOR a ee it 4 BO 81 1.19 ||Total Fe...... 72O2\4\ PL. 78 | 15.24
Oe Sa 04 RS 7 esi 77anl|iSps Gres 3.020| 2.813] 2.340
BOR sin occ aoe .46 | 15.17 | 15.05
* Fresh Rock.
} Altered near the fresh rock.
{ Altered, most decomposed portion.
§ Pycnometer method.
On the assumption of constancy of alumina? the analyses may
be recalculated, and gains and losses estimated, as shown in Table II.
The change in total iron is worthy of note, in that there is a slight
loss shown in 2, with a marked increase in 3. A suggested explana-
tion is that during the early stages of alteration some soluble ferrous
compound was formed, which migrated, perhaps by capillary
action, to the outer zone before it was precipitated by oxidation to
t Tn this connection it may be noted that wells in or near the dikes are said to
yield water containing considerable amounts of lime, while those in the gneiss, farther
from the dikes, yield comparatively soft water. Unfortunately, no quantitative data
on these waters are available.
2G. P. Merrill, Rocks, Rock Weathering and Soils, p. 208.
204
the ferric condition.
ALBERT D. BROKAW AND LEON P. SMITH
That the removal of ferrous iron may take
place in the early stages of alteration has been commonly recog-
nized.*
TABLE II
I 2 Gain Loss 3 Gain Loss
SiOpe sce 5m ewer eee Aisa Koye |e atyaceyel |e. sas 2OR 22.3) ate Gi) || eats eeae 32.65
AOS se ee cee 7S Dia! | 7 en 2a | ee ll oe RS T7:..5 2) || 2 ey
HeOheiocs +c cee By 6.97 St ately ate 11.66 8: 54clia se eee
PeOe coos oan eh eee 6.99 Qt AIS Paar een 2 AMS Ase NONE |p eee 6.99
MaOcrnudie? iaesieeere 4.67 Tx GOR h eae ne 2.81 S30) (Sarees 4.36
CaO visio sone eee E750: | A Oia = Ae aie 12.63 A 34 all< eee 17.16
INGO. cid eee 2.39 BCOVI heats onder 1.45 SR Ol ees 5c 2.18
KO. 37 5 OMe eeness .87 HOAs Sets sae 73
H,0— OA Gi anes 3 PAO tescros 2.36 2:32: eae
H,O+ .46 9.29 SFO iste sie yets 8.06 7, OO hadeneene
iO. choc ne eee AB ses o | Gach create 20 COS alc hity Nene a23
MnO... cdiecusnoseeeee .47 COTeN oilers ae § FiO) EE? wiyeccueeee .47
CO} ee eee eee none 577 ROP Ale corse 28 /28) |) eee
Sa cis pa era rors Hist: .10 HODwilaicer ence JOS!s| WAMONE! |e eee 10
Totalcc «Ss he eee eee LOOMIOs | WOTS3 Of il ose teal hse 53.295) leone 2s Cee
Total Bey xs. yess 7.62 GA2Te en eee cine 4.05 9.33 1. 707
Essentially the same relations are shown by the ‘“‘straight line”’
In Fig. 4 the analyses of the altered portion
diagrams of Mead.?
are compared with that of the fresh rock. The full line represents
analysis 2, and the broken line analysis 3. In general, 3 is merely
an accentuation of 2, except for potash and total iron, both of which
show a change of sign in the direction of change. It is apparent
that in the later stage of alteration the removal of bases continues,
and that it is out of proportion to the further removal of silica as
compared with 2. The retention of potash is by no means unusual.
In Table III the analyses are recast to molecular proportions to
emphasize some of the chemical and mineralogical features. It is
to be noted that even in analysis 2 the amount of silica is insufficient
to combine with all of the alumina to form kaolin. The alumina:
silica ratios areas follows: 1, 524.3632, 371257; 3, 1:1.10, Farka.
olin 1:2 is required. On the extreme assumption that all of the silica
in 3 is present in the form of kaolin, the analysis may be said to
tC. K. Leith and W. J. Mead, Metamorphic Geology, p. 22, Henry Holt & Co.
(1915).
2W. J. Mead, Econ. Geol., VII (1912), 141-44.
ZONAL WEATHERING OF A HORNBLENDE 205
represent (by weight) kaolin, 50 per cent; limonite, 25 per cent;
bauxite, 18 per cent; other substances, 7 per cent. It is highly
probable that part of the silica is present in some compound not
containing alumina, and if so the amount of bauxite is correspond-
ingly greater. This lends a distinctly bauxitic-lateritic aspect to
the alteration.
Fic. 4.—“ Straight line diagram”’ showing changes in composition with alteration.
The full line represents analysis 2, the broken line analysis 3, compared with the
analysis of the fresh rock.
TABLE III
Per cent+mol. wt.
I 2 3 I 2 B
SiOz sae 747 431 387 CaOuan eae: .312 .142 013
INGOR 6 sods c a 7i2 . 280 1320 |\Na.O).-. 3) - 039 025 006
WE oo dec .020 .070 eX, WLRAD Se bo0 3 O15 .008 013
EO se Becks .097 .056 ooo |{/H.O+..... .026 845 .836
MgO...... . 116 .075 .OT4 COR oes . 000 .003 .O12
Specimens similar to the one studied are not uncommon in the
weathered part of the dikes, and the changes shown are believed,
to be fairly typical for the rock in question. It is to be noted that
the fresh rock is much richer in iron than rocks which yield bauxite
deposits, and richer in alumina than those yielding high grade
laterite deposits.
REVIEWS
Lockatong Formation of the Triassic of New Jersey and Pennsyl-
vania. By A. C. Hawkins. Annals N.Y. Acad. Sci., XXIII.
145-76, Plate 1, January 27, 1914.
The Lockatong formation is the middle member of the Newark
series of the Triassic, extending from a point just west of Phoenixville,
Pennsylvania, to Princeton, New Jersey. The rocks of the formation
are dense, fine-grained, massive argillites, with some shales. The forma-
tion as a whole has a decidedly lens-like character. On the basis of the
general structure, lithologic character, and type of fossils, which include
estheriae, fish-scales, ostracods, and plant remains, it is concluded that
the sediments were laid down near the center of an inland basin. The
particles of the argillite are for the most part cemented by silica, which
renders the formation very hard and a pronounced ridge-maker. The
color of the beds is due to iron in various states of oxidation. The
boundaries of the Lockatong are very uncertain, owing to the fact that
it passes by a series of transitional dovetailing strata into the other
formations of the Newark. Since part or all of the Lockatong may be
contemporaneous with portions of the Stockton and Brunswick forma-
tions elsewhere, it seems that as a definite geological time unit the
Lockatong is valueless. There are three principal joint directions in the
Lockatong formation, the most important of which is remarkably con-
stant, and extends into the borders of a diabase mass near Rocky Hill,
which is interpreted as an extension of the Palisade sill. Titanium
minerals, brookite and ilmenite, are found in this major joint series,
apparently far removed from the diabase. Analcite and barite also
occur. That these minerals are derived from the igneous rocks is indi-
cated by similar occurrences in New Jersey elsewhere. Parts of the
Lockatong argillite are very well adapted for commercial use.
R: C. Me
Geological Map of Tennessee. Compiled by Otar P. JENKINS,
A. H. PurpvueE, State Geologist.
This map represents Archean, Cambrian, Ordovician, Silurian,
Devonian, Mississippian, Pennsylvanian, Cretaceous (Upper), Eocene,
Pleistocene, and Recent formations. Few states have so wide a range
206
REVIEWS 207
of systems, Proterozoic, Permian, Lower Cretaceous, Miocene, and
Oligocene only being absent. Pliocene (Lafayette) is indicated in
the legend of the map but. not shown on the map itself, and the legend
seems to be intended to throw doubt on the validity of the formation
in Tennessee.
Under the designation “Columbia Formation,” loess, loam, and loose
sand are grouped. This seems to us an unfortunate classification.
The “Terrace Deposits” of the map are quite as appropriately classed as
“Columbia” as the loess and loam which are so classed. We are of the
opinion that the use of the term ‘Columbia Formation” should be dis-
continued (though possibly the term “‘Columbia Series”? may be useful
to include all Pleistocene non-glacial formations). What was originally
grouped under the name Columbia included several formations of which
the probable equivalents of the Terrace Deposits of this map were a chief
member. ‘Loess’? would seem to be an adequate designation of the
deposits included under that term, without classing them as Columbia.
Their classification as Pleistocene seems. altogether adequate. The
loess, of many regions at least, is of very different ages, and all of it
does not belong to one formation in the chronological sense.
The map is distinct and represents sufficient change from its prede-
cessors to be welcome. It is accompanied by elaborate explanatory
legends and by four cross-sections which represent well the structure
of the formations in the state.
The map may be had by application to the State Geologist, Nash-
ville, Tennessee. Postage, 8 cents.
ReaD aS:
Cretaceous Deposits of the Eastern Gulf Region, and Species of Exogyra
from the Eastern Gulf Region and the Carolinas. By L. W.
STEPHENSON. U.S. Geol. Surv., Prof. Paper 31, 1914. Pp.
is, OS Ait, (Goetecs,'o).
In eastern Alabama and Georgia a terrane, previously regarded
as forming the eastward extension of the Tuscaloosa series of western
Alabama, has been shown by its unconformable relations with overlying
formations, lithologic character, and contained plant fossils to be of
Lower Cretaceous (Comanchean) age, though probably somewhat
younger than the Patuxent. Belonging to the Upper Cretaceous
(Cretaceous) of the eastern Gulf region are four formations, Tusca-
loosa (regarded as Lower Cretaceous), Eutaw, Selma chalk, and
208 REVIEWS
Ripley. The first, consisting of irregularly bedded sands, clays, and
gravels, has an estimated thickness of 1,000 feet and rests unconformably
on a basement of Paleozoic metamorphics, and in the east on Pre-
Cambrian crystalline rocks and in part on Lower Cretaceous. The
Eutaw formation, somewhat similar to the Tuscaloosa in lithologic
character, is believed to be entirely marine, though much of the formation
was doubtless laid down in very shallow water. It is 400-500 feet thick,
rests conformably on the Tuscaloosa, and is overlain conformably in
part by the Selma chalk, and in part by the Ripley formation. The
Selma chalk consists mainly of more or less argillaceous and sandy
limestones rendered chalky by their large content of foraminiferal
remains. It is abundantly fossiliferous in certain portions, yielding
large numbers of the Exogyra described in the latter portion of the
paper. The Selma grades into the sandy member of the Tuscaloosa,
and the clastic beds of the Ripley formation when followed along the
strike. A thickness of 930 feet of the chalk formation has been measured
in western Alabama. The Ripley formation, 250-350 feet in thickness,
consists typically of calcareous and glauconitic sands, sandy clays, and
impure limestones and marls of marine origin. It extends through parts
of the Gulf states from southern Illinois to Georgia. A study of the
faunas of the various formations is detailed, and correlations with other
Cretaceous regions indicated by chart.
A description of the genus Exogyra, which includes three species
with two varieties, constitutes the second portion of the paper.
RC. Me
The Jurassic Flora of Cape Lisburne, Alaska. By F.H. KNowLton.
U.S. Geol. Surv., Prof). Paper 85; Part D, 1914: Pp. 25; plsyze
The Jurassic of the Cape Lisburne area is estimated to have a very
great thickness, 15,000 feet, and contains from 40 to 50 coal beds which
range in thickness from 1 or 2 feet to over 30 feet. Plant collections
from this area show 17 species of well-defined Jurassic types. The close
similarity or identity of a number of forms with species from eastern
Siberia and Mongolia is noteworthy. The flora indicates a warm-
temperate or subtropic climate and the geographic range, especially into
the Arctic and Antartic, is suggestive of the uniform mildness of the
Jurassic earth-climate.
RCE
| Outlines of Geologic History with
Especial Reference to North America
Symposium Organized by
BAILEY WILLIS
Compilation Edited by
ROLLIN D., SALISBURY
; = and all readers of geologic
literature will welcome the publication,
in book form, of an important series of
essays and discussions on the subject of geologic
1 correlation under the title, Outlines of Geologic
| History with Especial Reference to North America.
| They embody the present state of knowledge
| and opinion concerning many of the funda-
| mental problems of North American geology,
| and form an admirable supplement to earlier
| treatises and manuals.
| The value of the book is greatly enhanced
| by the fifteen paleogeographic maps by Bailey
| Willis which accompany the papers.
316 pages, 810, cloth; price $1.50, postage extra
(weight 2 Ibs.)
2 The University of Chicago Press
| Chicago - - Illinois
S— \
a
in correcting the proofs of Vol. IT.
or $15 net in half-leather.
A HISTORY OF ARCHITEGTUR
Vol. 1: Antiquity. Vol. il: Romanesque and Oriental. Vol. Ill: Gothic in Europe. Vol. IV: Gothic in England, Renaissance, Modern Architecture
This is the most extensive study of architecture in the English language, being the first attempt to cover exhaustively the
development of architectural form from the earliest monuments of Egypt and Chaldea to the buildings of the present day.
The work was originally planned by Russell Sturgis more than ten years ago to be a complete survey of the architectural
expression of the various peoples throughout theages. Mr. Sturgis unfortunately died before the publication of the second
volume in rg09. The completion of the work was thereupon undertaken by A. L. Frothingham, who had assisted Mr. Sturgis
THE BAKER & TAYLOR CO
FINE INKS 482 ADHESIVES
For those who KNOW
Drawing Inks
Eternal Writing Ink
Engrossing Ink
Taurine Mucilage
Photo Mounter Paste
Drawing Board Paste
Liquid Paste
Office Paste
Vegetable Glue, Etc.
Are the Finest and Best Inks and Adhesives
Emancipate yourself from the use of corrosive and
ill-smelling inks and adhesives and adopt the
Higgins Inks and Adhesives. They will bea
revelation to you, they are so sweet, clean, well
put up, and withal so efficient.
At Dealers Generally
Higgins’
CHAS. M. HIGGINS & CO., Mfrs.
Branches: Chicago, London
271 Ninth Street Brooklyn, N.Y.
Daus Improved Tip Top Duplicator
will reproduce them _ easily—quickly—neatly—cheaply.
The simplest and quickest duplicator on the market.
Makes rso handwritten copies or 50 typewritten copies in
afew minutes. No expensive supplies to buy. Lasts a
lifetime. No printer’s ink. No smudged copies. No
soiled hands. Ready instantly. Negatives require no
washing out after using. Complete outfit contains a con-
tinuous roll of Daus Non-Peeling Anti-Stick Negative
Roll, which can be used over and over again. Cap size
83x13 inches. Price complete $5.00.
Ten days’ free trial without deposit
LIX K. DAUS DUPLICATOR CO.
Daus Building, 111 John Street, NEW YORK
Volumes | and I by RUSSELL STURGIS
Volumes Ill and IV by A. L. FROTHINGHAM
Description of the Volumes :
The volumes are royal octavo, size 73 X to}, and contain about 400 pages each. The volumes are bound in two styles
—one a serviceable blue cloth with gold stamping and tops; the other a brown half-morocco with cloth sides for those who
require a more enduring form. ‘The paper is heavy coated, of fine quality, to reproduce the illustrations to the best ad-
vantage, deckle edged. The type used is large and clear. A complete index will be found at the end of Vol. IV.
4 Price and Conditions
The price of A History of Architecture, complete in four volumes, cloth, is $20 net; half-leather, $30 net. For the advan-
tage of those who purchased Vols. I and II when they were published, Vols. III and IV will be sold for $ro net in cloth,
Wholesale Dealers in the Books of All Publishers
e 354 Fourth Ave., NEW YORK, at Twenty-sixth St.
A Simplified Typewriter
The
Remington Junior
Small in size—but big in Capacity
Light in weight—but heavy
in stability
Remington-built Remington-guaranteed
Price $50.00
Easy payment terms can be
arranged if desired
Write for Catalogue
REMINGTON TYPEWRITER GO.
(Incorporated)
New York and Everywhere
Do You Want to Know
What Your Handwriting
Reveals?
WE have published “a fascinating
booklet of 32 pages on the sub-
ject of graphology, by William Leslie
French. Every reader of this publi-
cation will be interested in comparing
the examples of handwriting in judg-
ing character and disposition of the
writer.
A copy of this booklet and 12 differ-
ent patterns of The Spencerian
receipt of ten cents.
If you can do good work witha poor pen
you can do better work with a good pen.
Silver plated Falcon pens, smooth points,
wear long, will not corrode.
SPENCERIAN PEN CO.
349 Broadway - - New York City
Steel Pens will be sent postpaid on |
MICROSCOPE FS2 Ki
7.5X Eyepiece; two objectives, 16 mm. (3 in.) and 4 mm.
(4 in.) in dustproof revolving nosepiece. Price $34.00
Unexcelled for all-round
Laboratory uses
Several of our notable improvements are involved
in this example of the superiority of the
Bausch loa
Microscopes
It has our lever type of side fine adjustment—simple,
practical, and durable. The rate of movement is correct
for both high- and low-power objectives.
The stage is large and is completely covered with vulcan-
ized rubber. Its diaphragm is operated by a milled ring,
from any point of its circumference. ‘
The long handle arm is curved to give graceful appearance
and proper balance—also to afford more than usual space
for manipulation of the object.
Optical equipment and mechanical construction of the
highest standard.
Special Terms to Educational Institutions
Write for illustrated price list of all models from $2.50 up
Bausch £5 lomb Optical ©.
412 ST. PAUL STREET ROCHESTER, N.Y.
New York Washington Chicago
Leading American Makers of Photographic and Ophthalmic
Lenses, Projection Lanterns (Balopticons), Stereo-Prism Binocu-
lars, and other high-grade optical products. Spit
San Francisco
Go MOLUME XV". NUMBER 3
— THE ;
JOURNAL orf GEOLOGY
A SEMI-QUARTERLY
iin pride : EDITED By
THOMAS C. CHAMBERLIN AND ROLLIN D. CHa Surtees:
With the Active Collaboration of
SAMUEL W. WILLISTON, Vertebrate Paleontology ALBERT JOHANNSEN, Petrology
pelea WELLER, Invertebrate Paleontology ROLLIN T. CHAMBERLIN, Dynamic Geology
: ALBERT D. BROKAW, Economic Geology
’
ASSOCIATE EDITORS
‘SIR ARCHIBALD GEIKIE, Great Britain JOSEPH P.IDDINGS, Washington, D.C.
CHARLES BARROIS, France JOHN C. BRANNER, Leland Stanford Junior University
ALBRECHT PENCK, Germany ; RICHARD A. F. PENROSE, Jr., Philadelphia, Pa.
HANS REUSCH, Norway WILLIAM B. CLARK, Johns Hopkins University
GERARD DEGEER, Sweden WILLIAM H,. HOBBS, University of Michigan
“TT. W. EDGEWORTH DAVID, Australia FRANK D. ADAMS, McGill University
- BAILEY WILLIS, Leland Stanford Junior University CHARLES K, LEITH, University of Wisconsin
GROVE K. GILBERT, Washington, D.C. WALLACE W. ATWOOD, Harvard University
CHARLES D. WALCOTT, Smithsonian Institution WILLIAM H. EMMONS, University of Minnesota
' HENRY S. WILLIAMS, Cornell University ARTHUR L. DAY, Carnegie Institution
= es APRIL-MAY 10916
on aE A. DERBY BR Pa PF yee: Semen 8b a ith en canmaneanine SOHN Ca BRANNERS 0/300
gcieslgges) OF PRISMATIC STRUCTURE IN IGNEOUS ROCKS - - Ropert B. SOSMAN = 215
_ ELLIPSOIDAL LAVAS IN THE GLACIER NATIONAL PARK, MONTANA
LANCASTER D. BuRLING 235
THE ORIGIN OF RED BEDS. A STUDY OF THE CONDITIONS OF ORIGIN OF THE
PERMOCARBONIFEROUS AND TRIASSIC RED BEDS OF THE WESTERN
UNITED STATES: PART II - - - - - - - C.W. Tomitnson 238
‘THE ACADIAN TRIASSIC. PART II - - - - - - - SIDNEY POWERS 254
THE LOMBARD OVERTHRUST AND RELATED GEOLOGICAL FEATURES
Wintoror P. HAYNES 269
THE SKELETON OF TRIMERORHACHIS - .-. - .- .-.--...8..W. Wituston. — 201
JEL PL POE aR nat eel an Naar pa ea ey ines
eR PUETTCA TIONS ree PET sh ween me gor 6 kaa ode Sunes See Sarg
MeN Bol TY OR CHICAGO.-PRESS
CHICAGO, ILLINOIS, U.S.A.
AGENTS \
THE CAMBRIDGE UNIVERSITY PRESS, Lonpon anv EDINBURGH
KARL W. HIERSEMANN, Letpzic
THE MARUZEN-KABUSHIKI-KAISHA, Toxyo, Osaka, Kyoto
' ‘THE MISSION BOOK COMPANY, Suancuat
THE JOURNAL OF GEOLOGY
EDITED BY
THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
With the Active Collaboration of ,
SAMUEL W. WILLISTON ALBERT JOHANNSEN
Vertebrate Paleontology ee" Petrology
STUART WELLER - ROLLIN T. CHAMBERLIN
Invertebrate Paleontology Dynamic Geology
ALBERT D. BROKAW
Economic Geology
The Journal of Geology is published by the University of Chicago at the University Press semi-
quarterly, on or about the following dates: February 1, March 15, May I, June 15, August 1, September 15,
November 1, December 15. ‘[ The subscription price is $4.00 per year; the price of single copies is
65 cents. Orders for service of less than a half-year will be charged at the single-copy rate. {J Postage is
prepaid by the publishers on all orders from the United States, Mexico, Cuba, Porto Rico, Panama Cana}
Zone, Republic of Panama, Ilawaiian Islands, Philippine Islands, Guam, Samoan Islands, Shanghai
| Postage is charged extra as follows: For Canada, 30 cents on annual subscriptions (total $4.30), on
single copies, 4 cents (total 69 cents); for all other countries in the Postal] Union, 53 cents on annual
subscriptions (total $4.53), on single copies, 11 cents (total 76 cents). [Patrons are requested to make
all remittances payable to the University of Chicago Press in postal or express money abe or bank
drafts.
The following agents have been appointed and are authorized to quote the prices indicated:
For the British Empire: The Cambridge University Press, Fetter Lane, London, E.C. Yearly
subscriptions, including postage, 18s. 8¢. each; single copies, including postage, 3s. 2d, each.
For the Chinese Empire: The Mission Book Company, 18 Pekin Road, Shanghai, China.
Yearly subscriptions, $4.00; single copies, 65 cents, or their equivalents in Chinese money. Postage
extra, if mailed direct outside of Shanghai, on yearly subscriptions 53 cents, on single copies 11 cents.
For the continent of Europe: Karl W. Hiersemann, Konigstrasse 29, Leipzig, Germany. Yearly
subscriptions, including postage, M. 22.65 each; single copies, including postage, M. 3.80 each.
For Japan and Korea: The Maruzen- Kabushiki-Kaisha, 11 to 16 Nihonbashi Tori Sanchome,
Tokyo, Japan. Yearly subscriptions, including postage, Yen 9.00 each; single copies, including
postage, Yen 1.50 each. ;
Claims for missing numbers should be made within the month following the regular month of
publication. The publishers expect to supply missing numbers free only when they have been lost in
transit. \
Business correspondence should be addressed to The University of Chicago Press, Chicago, Ill.
Communications for the editors and manuscripts should be addressed to the Editors ‘oF THE
JOURNAL OF GEOLOGY, the University of Chicago, Chicago, Ill.
Contributors are requested to write scientific and proper names with particular care and in citations
to follow the form shown in the pages of the Journal.
__ Separates, if desired, must be ordered in advance of publication. Separates of leading articles will be
printed as ordered, of which 50 (without covers) will be furnished gvaéis, the actual cost of the remainder
(and covers, if desired) to be paid for by the author. The actual cost may vary, and will depend upon
the amount of work in re-making the pages into forms, presswork, paper, binding, etc. Separates
containing half-tones may be expected to cost somewhat more, the increase depending upon - number
of cuts and the amount of work required upon them.
Entered as second-class matter, March 20, 1893. at the Post-office at Chicago, IIl., under the Act of March 3, 1879.
VOLUME XXIV NUMBER 3
THE
JOURNAL OF GEOLOGY
APRIL-MAY 1916
ORVILLE A. DERBY
JOHN C. BRANNER
Leland Stanford Junior University
Orville Adelbert Derby, for many years one of the associate
editors of this Journal, was born at Kelloggsville, New York, on
July 23, 1851, and died by his own hand at Rio de Janeiro, Brazil,
on November 27, 1915.
After graduating at the high school, Derby entered Cornell
University in 1869, taking what was then called the scientific course.
While he was yet a Freshman, however, he became so interested
in geology and was such a promising student that he was selected
by Professor Charles Fred Hartt, then professor of geology at
Cornell, to accompany him on a trip to Brazil in the summer of
1870. That was the first trip made to Brazil by Derby; it deter-
mined both his career and the whole course of his life. On his first
voyage he visited Pernambuco, and made the first considerable
collection of fossils ever made at Maria Farinha, a locality that
has since been looked upon with especial interest by students of the
Mesozoic history of South America.
In the summer of 1871 he went to Brazil with Hartt again, this
time visiting the Amazon valley and making an important collec-
tion of Carboniferous fossils from the limestones at Itaitiba on
the lower Tapajos River.
Vol. XXIV, No. 3 209
210 JOHN C. BRANNER
In 1873 he graduated from Cornell University with the degree
of Bachelor of Science, and the year following he continued his
geological studies for the Master’s degree, which he received in
June, 1874. His thesis was “On the Carboniferous Brachiopoda
of Itaitiba, Rio Tapajos,’’ and was published as No. 2 of Vol. I
of the Bulletin of Cornell University, Ithaca, 1874. That was
Derby’s first publication on the geology of Brazil, and it is not only
a valuable paper in itself, but it is especially interesting in view
of subsequent developments. The Itaitiba fossils were in com-
pact limestone, but as they were silicified they could be obtained
in satisfactory form only by dissolving away the surrounding rock
—a long and tedious process which would have thoroughly dis-
couraged most young men of Derby’s age. The spires of many of
the specimens of these brachiopods have seldom been surpassed
for delicacy and perfection.
The art of illustration was far from being so well developed in
those days as it is now, and we thought ourselves very fortunate
in being able to make and use the crude photographs with which
that paper was illustrated.
In 1873 Derby was appointed instructor in geology at Cornell,
and in the summer of 1874 Professor Hartt made arrangements to go
to Brazil again. Leave of absence was obtained, Derby was placed
in charge of the work of instruction in the department, and in Sep-
tember, 1874, Hartt went to Brazil again, taking Branner with
him as his only assistant and going by way of Europe. It-is often
said that Hartt went to Rio on the invitation of the Brazilian
government or of the Emperor D. Pedro II. As a matter of fact
he went entirely on his own responsibility and without invitation
from anyone, but with the idea’ of inducing the Brazilian govern-
ment to establish a geological survey under his direction.
Arriving in Rio de Janeiro, he at once devoted all his energies
to interesting the leading men in a geological survey of the empire,
and by the end of the year the survey was authorized and provided
for, and O. A. Derby, Richard Rathbun, and E. F. Pacheco Jordao
were named as assistants of the new “‘Commissao Geologica do
Imperio do Brasil.”’ In December, 1875, Derby reached Rio de
Janeiro and began his work under the government. He held this
ORVILLE A. DERBY 25E
position less than two years, for through a change of ministry the
survey was abolished in 1877, and Hartt died in Rio that same
year. Shortly after the suspension of the survey, however, Derby
was given a position in the National Museum at Rio as curator in
charge of geology, a position which enabled him to continue his
studies on the geology of Brazil, and, to a certain extent, to pre-
serve the results of the work of the extinct survey. He remained
in the museum until 1886 when he was made state geologist of the
Brazilian state of Sao Paulo.
The establishment of the Sao Paulo survey was a step of great
importance to geological science in Brazil, for Derby’s knowledge
of and interest in the geology of the country as a whole enabled
him to grasp more firmly the geological problems of that particular
state, and at the same time he became and remained, up to the
time of his death, the leading authority on the geology of Brazil.
He was state geologist of Sao Paulo until 1904, when he resigned.
In 1907 a new federal geological service was provided for, and
Derby was made its chief, a position he held during the rest of his
life.
The first edition of Branner’s Geologia Elementar, a work pre-
pared especially for Brazilian students of geology, was thus dedi-
cated: ‘To Orville A. Derby, who has devoted his life to the study
of the geology of Brazil, and has done more than anyone else to
solve its many problems, this work is affectionately dedicated.”’
This is a brief and mild statement of Derby’s great services to
Brazil and to the science of geology, without mentioning his many
other services to science and to that country.
First and last Derby was a paleontologist. He had no fond-
ness for administrative work; he was but little interested in struc-
tural geology or in its methods; he was forced by circumstances
into some acquaintance with microscopic petrography; but his
interest in paleontology was genuine, deep, and all-comprehensive.
From all the cares of office and the worries of life he found relief
and happiness in boxes of poorly preserved fossils that most
paleontologists would have put away as not worth while.
It was chiefly to this interest of his in paleontology that we
owe Dr. C. A. White’s Contributions to the Paleontology of Brasil,
212 JOHN C. BRANNER
published at Rio in 1887; John M. Clarke’s Trilobites of the Ereré
and Maecuru Sandstones, Rio, 1896; Upper Silurian Fauna of Rio
Trombetas, Rio, 1899; Devonian Mollusks of the State of Parad, Rio,
1899;. and Devonian Fossils of Paranda, Rio, 1913. Besides these
excellent works there are many smaller papers on paleontology
that cannot be mentioned here, and there still remains unpublished
an important volume by D. S. Jordan on the Cretaceous fossil
fishes of Ceara.
During the last eight years Derby gave much of his time to the
study of Psaronius and its relationships. The last of his published
papers was on the stem structure of T7zetea singularis, and appeared ,
in the American Journal of Science for March, 1915, pp. 251-60.
Because he had to undertake work in regions but poorly supplied
with maps, one of his first and most important duties, when he
became state geologist of Sao Paulo, was the inauguration of topo-
graphic work. This work was intrusted to Horace E. Williams,
an able and energetic young American to whom the state of Sao
Paulo and the scientific world are indebted for an excellent series
of topographic maps on a scale of one to 100,000, to say nothing
of his explorations of the western portions of Sao Paulo, his work
on the Serra da Canastra, etc.
Derby’s own list of publications on the geology of Brazil num-
bers 125 papers. Naturally they embrace a wide range of sub-
jects. Ten of his papers relate to the geology and genesis of the
Brazilian diamonds. One of these, on the geology of the diamond
and carbonado region of the state of Bahia, was the first publication
to give an idea of the geology of that little-known district.
He became interested in the early cartography of Brazil, and
published a number of papers on that subject.
As an author and as a scientific reasoner he was an extremely
cautious man, so much so that the word “‘hedge”’ was constantly
on his lips both for his own guidance and as a warning to his
assistants.
The last evening I spent in his rooms at Rio de Janeiro he
referred to this personal trait, and remarked that it had prevented
his marrying—that he was too cautious to take the risk. This
cautiousness of his was probably the real reason for some of the
~
ORVILLE A. DERBY 213
long delays in publishing his results, delays which led to the tying
up of his own results and those of his assistants. Without doubt
“he hoped that the delays would enable him to put everything
beyond question and to make his reports final and complete instead
of preliminary and tentative. But the delays were prolonged from
year to year until his assistants became discouraged and the gov-
ernment more or less exasperated at the lack of practical results
for such great and long-continued expenditures. It was probably
this long delay that finally led to his resignation as state geologist
of Sao Paulo. 5
Derby never felt obliged to show results. After he had been
state geologist of Sado Paulo for ten or twelve years, and had pub-
lished next to nothing on the geology of that state, I asked him
point blank, and with some feeling, where his results were. He
replied: ‘‘They are in my head.” We had to change the subject.
But the important fact behind his delays is that the geology of Sao
Paulo is difficult and involves problems that he had not been able
to settle to his own satisfaction, and he was unwilling to commit
himself definitely to paper and thus lay himself open to adverse
criticism.
It seemed unfortunate for Brazil, for himself, and for the cause
of science that he was unable to bring himself to take an active
interest in the economic geology of the country. But his first and
only interest in geology was in geology as a pure science. To him
a fossil was a thing of beauty, of interest and value, and a joy
forever, but a mine or an industry was, after all, only an industry
whose main object was money-getting.
Derby was a man of unlimited grit. When once he decided
upon a course of action nothing turned him to the right or to the
left. His whole life is a demonstration of his power to make good
in spite of obstacles that would have been insurmountable for
most men—his determination to be the leading authority on the
geology of Brazil, cost what it might.
How many of us would have lived for forty years, in a foreign
country, cut off, as he was, from all personal contact with the
geologists of the world at large and from the people of his own race
and from his own family? And yet, from the time he went to Rio
214 JOHN C. BRANNER
in 1875 to the day of his death he visited the United States only
twice. One of these visits was in 1883 when he spent three
months at Washington; the other was in 1890 when he attended
the meeting of the American Association for the Advancement of
Science at Indianapolis.
When the Commissao Geologica was abolished in 1877 the rest
of us took to our heels. Not so Derby; he was not to be stampeded
by a simple lack of funds or of employment; he meant to save the
results of the work of Hartt and of his colleagues, and, in so far
as it could be done, he did it.
Personally Derby was one of the kindest-hearted and most
affectionate men I have ever known. His last dollar was at the
service of his friends, and his right hand knew nothing of the kind
deeds done by his left. The beggars in the streets found him their
easiest victim.
He was held in the highest esteem in the community in which
he lived. He stood for uprightness and honorable dealing, and he
was never the willing tool of designing adventurers. For many
years he has been justly regarded as the leading geologist in South
America, and his standing is due, not to the fact that there are but
few first-class geologists in South America, but to his ability and
to his excellent work.
In 1892 he was awarded the Wollaston prize of the Geological
Society of London, while his distinguished services led to his being
made one of the associate editors of the Journal of Geology and to
his election to membership in various learned societies in different
parts of the world. He was a frequent contributor to the American
Journal of Science and to this Journal.
A list of his papers on the geology of Brazil up to 1go09 is given
in the Bulletin of the Geological Society of America, XX, pp. 36-42.
To that list should be added thirteen additional titles of papers
that have appeared since its publication.
TYPES OF PRISMATIC STRUCTURE IN IGNEOUS ROCKS?
ROBERT B. SOSMAN
Geophysical Laboratory, Carnegie Institution of Washington
The question of the cause of columnar or prismatic jointing in
igneous rocks was thought to have been satisfactorily settled by the
writings of Thomson, Mallet, Bonney, Iddings, and others, until it
was reopened recently by the investigations of several French
physicists. As the subject seems to be in need of further discussion
and experimental study, I have brought together observations on
several hypotheses of prismatic jointing, hoping to show that
the study of these structures may yield much more precise
information than is now available as to the original conditions of
occurrence of the igneous rocks in which such structures are found.
CRYSTALLIZATION HYPOTHESIS
The first hypothesis as to the origin of prismatic structure which
had any experimental or observational basis was that of Gregory
Watt2 and may be entitled the “crystallization hypothesis.”’
Watt, in 1804, observed that a large mass of basalt which he had
melted down in a reverbatory furnace crystallized radially from
centers which were fairly regularly spaced in a horizontal plane;
the intersections of these radially growing fibrous bundles formed a
network of hexagonal partings through the mass, leading Watt to
the conclusion that this manner of crystallization, by its vertical
extension upward from the base of a mass of basalt, must have been
the cause of the prisms found in the Giant’s Causeway, Fingal’s
Cave, and elsewhere.
x Presented before the Geological Society of Washington, April 28, 1915.
2 Gregory Watt, ‘Observations on Basalt, and on the Transition from the Vitreous
to the Stony Texture,” etc., Phil Trans., 1804, pp. 279-314- Watt also explains
clearly the contractional origin of such structures as mud and starch prisms.
215
‘
216 ROBERT B. SOSMAN
This explanation seems to have been satisfactory to many of
the earlier authors of geological treatises,’ but before many years
had passed doubts began to arise as to whether this process could
have been an efficient cause of the numerous cases of columnar
structure which began to accumulate in geological literature as
travel became more extensive and observations multiplied. James
Thomson? in 1863 urged that contraction of a homogeneous mass
was a sufficient cause for all columnar structure, and that the
hypothesis of crystallization from centers was unnecessary and
improbable. Mallet’ discussed the contraction hypothesis in detail,
showing how it would account, in his opinion, for all of the struc-
tures found in columnar rocks. Bonney,’ Iddings’ and others have
followed the same lines of argument.
CONTRACTION HYPOTHESIS
The radial-contraction hypothesis is still the explanation gen-
erally accepted by the textbooks, and perhaps applies in the
majority of cases of prismatic structure. But a much more com-.
plete discussion of this hypothesis than has yet been published
could be profitably made, for there has been no attempt at any
quantitative application of it to actual occurrences. It has served
hitherto simply as a qualitative explanation: The relation of the
size, shape, curvature, jointing, and other properties of the columns
to the original temperature, viscosity, and rate and manner of cool-
ing of the rock is capable of more exact definition.
For instance, the time factor in cooling in its relation to the
elastic properties of the rock does not seem to have been considered
* More or less vaguely associated with this definite hypothesis was the idea of a
“‘concretionary force” which is frequently referred to. The idea that columns might
be due to the mutual compression of actual spheroids of lava (now understood as
‘‘pillow”’ lava) was also more or less confused with the crystallization hypothesis.
Watt’s idea of the matter seems to have been perfectly clear, but Mallet, for instance,
misunderstands Watt’s “‘mutual compression of spheroids” to mean actual compres-
sion (Phil. Mag., L [1875], 221-24); the words “mutual interference of radially
growing spheroids” state Watt’s meaning more clearly.
2 Brit. Assoc. Rep., 1863, Abstract, p. 89.
3 Phil. Mag. (4), L (1875), 122-35, 201-26.
4 Quar. Jour. Geol. Soc., XXXII (1876), 140-54.
5 Amer. Jour. Sci., XX XI (1886), 321-31.
PRISMATIC STRUCTURE IN IGNEOUS ROCKS —_.217
in previous discussions. If the mass is cooling slowly, the crystal-
lized shell may be able to adjust itself by a slow movement to the
stress produced by contraction, so that the strain does not for some
time pass a given value. If the cooling is rapid, on the other hand,
the strain may be rapidly raised through the inability of the mass
to flow as rapidly as the stress is applied. Under conditions of
rapid cooling, therefore, the temperature at which the stresses
become sufficient to produce rupture will be higher than under
conditions of slow cooling." :
- Another point concerns the conditions of rupture. Published
discussions of formation of columns by contraction have tacitly
assumed that the condition of rupture is that the extension shall
exceed a certain limiting value. This is only one out of several
possible conditions of rupture. Various hypotheses have been pro-
posed by physicists (limiting tension, limiting positive or negative
strain, limiting shear), of which the best founded experimentally is
that of Tresca and Darwin, according to which rupture occurs when
the maximum difference of the greatest and least principal stresses
. reaches a certain limiting value.? Although the acceptance of this
condition of rupture as the fundamental one does not simplify the
problem of calculating the actual physical magnitudes of tempera-
ture, temperature gradient, stress, and strain in any given case, yet
it should permit a more complete analysis of the kinds of structure
that will result from different conditions of cooling. Such an
analysis is; however, beyond the scope of the present article.
CONTRACTION OF PHYSICALLY HETEROGENEOUS MATERIAL
Prismatic structure is very common in materials which are
heterogeneous as regards their state of aggregation (such as mud
and wet starch), that is, in which solid matter is suspended in or
mixed with a liquid. It is a question whether the formation of a
prismatic structure in such materials is strictly comparable with
most cases of contraction prisms in igneous rocks. The pr-ncipal
The above-mentioned effect of the rate of cooling is quite distinct from the
commonly recognized effect, which appears in the temperature gradient away from the
surface of the cooling mass.
2 Love, Theory of Elasticity, 1906, p. 119. \
218 ROBERT B. SOSMAN
difference is in the strength of the materials. Very considerable
stresses may accumulate in a glassy or crystalline rock before rup-
ture occurs, and when it does occur, the crack extends suddenly a
considerable distance into the mass. A layer of wet mud, on the
other hand, accumulates practically no stresses, as the forces of
cohesion and liquid surface tension to be overcome are very small.
The cracks therefore form much more gradually, and grow little by
little as desiccation proceeds. ‘They have even been observed to
form under water,’ probably as a result of freezing and melting.”
It is possible that some basalt prisms have been formed in the
same way as the slowly formed mud cracks, by the slow shrinkage
of a material which is partly solid and partly liquid, for the normal
course of crystallization of an igneous rock consists in the separation
of certain portions as crystals while the remainder stays liquid until
a lower temperature is reached. It has been commonly observed,
however, that the boundaries of contraction columns frequently
cut across the crystals of the rock, showing that solidification was
practically complete before the crack formed. ;
An example of prismatic, although not columnar, structure pro-
duced in this manner is probably to be found in the ‘‘apparent sun-
crack structure in diabase,” described by Wherry as occurring in
the upper surface of the great diabase sill of Pennsylvania, west of
Philadelphia. He explains it as due to contraction jointing fol-
lowed by the penetration of still liquid material into the cracks from
below. At first sight this occurrence has some of the characteristics
of prismatic structure due to liquid convection accompanied by
segregation, but a re-examination of the structure by Dr. Wherry
and the author in May, 1915, showed that the angles and polygons
t Moore, Am. Jour. Sci., XX XVIII (1914), 101-2.
2 Mud cracks may also belong to the other types of columnar structure. Where
the deposit is very fine grained and homogeneous, the walls of the columns may show
the feathery patterns characteristic of a fractured solid, resulting from breaks (either
sudden or slow-growing) which occurred when the material was nearly dry, and
indicating the existence of tensional stresses. On the other hand, a prismatic structure
of apparently convectional origin has been observed by Guillaume (Soc. Franc. Phys.,
Bull. Seances, 1907, pp. 50-51) in mud flows in sub-Arctic regions.
3 E. T. Wherry, “‘Apparent Sun-Crack Structures and Ringing-Rock Phenomena
in the Triassic Diabase of Eastern Pennsylvania,” Acad. Nat. Sci., Philadelphia, Proc.,
LXIV (1912), 169-72.
PRISMATIC STRUCTURE IN IGNEOUS ROCKS 219
are those produced by contraction, not by convection (see p. 22 ie
A photograph of the occurrence is shown in Fig.1. An examination
by Wherry of the cross-section of one of the small ‘“‘dikes’’ shows
that it has an irregular boundary, that it grades off without a sharp
break into the surrounding rock, and that it is more coarsely crys-
talline than the surrounding material. It appears to be, therefore,
a case of prismatic structure due to contraction in physically hetero-
geneous material, and quite distinct from the usual type of con-
traction prisms. Dr. N. L. Bowen, of this laboratory, informs me
that he has seen a similar structure in the upper surface of a diabase
sill north of Lake Superior.*
CONVECTION HYPOTHESIS
E. H. Weber? described in 1855 a phenomenon observed by him
on microscope slides on which a solid was being precipitated from
alcohol-water mixtures. The liquid was observed to circulate and to
divide itself up into regular polyhedral cells. A similar phenomenon
was observed by James Thomson! in 1882, in a soap solution. It
remained for the French physicist Bénard,* in 1900, to make a
really thorough study of the subject, and his experiments have
brought out a number of new and interesting facts.
A polygonal structure is easily produced in a layer of liquid
which is shallow in comparison with its horizontal extent, and which
is losing heat from its upper surface or is gaining heat from its
lower surface. If the top surface is cooler than the bottom, then
the colder and denser liquid at the top tends to sink and the warmer
bottom layer to rise, and convection currents must be set up: if
the conditions are uniform and constant, a steady state of flow of
some kind must ultimately be set up. In a flat liquid sheet of
indefinite extent this state of flow must take the form of parallel
rising and descending currents, and these will flow with minimum
«Canada, Bur. Mines, Ann. Rep., XX (1911), 125-26.
2 Pogg. Ann., XCIV, (1855) 452-59-
3 Phil. Soc. Glasgow, Proc. XIII, (1882), 464-68. Thomson recognized the simi-
larity of the pattern to that of the Giant’s Causeway.
4H. Bénard, Les tourbillons cellulaires dans une nappe liquide, etc., thesis, Paris,
1901; Rev. gén. Sci., XI (1900), 1261-71, 1309-38.
ROBERT B. SOSMAN
220
“eluvA[ASUUO
‘erydjapeiyd JO }SoM [IIs aseqetp Jo doy, “[erayeuI snoauasosoyoy Aqpeoisyd ut uorjseI}UOD 0} onp sinjonI}s OeUSTIG—I “OI
PRISMATIC STRUCTURE IN IGNEOUS ROCKS 221
friction only when they divide the liquid into hexagonal cells, as
can be shown by the same line of argument as is used to prove that
a uniform shell, under tension due to its own contraction, breaks
with minimum energy expenditure when it divides into hexagons.
Fig. 2 is a cross-section of one of these hexagonal cells, showing
how the currents rise in the middle of each prism and flow down at
FREE SURFACE
!
{
|
|
|
|
|
|
|
|
|
|
|
eee we we ea
U/
Fic. 2.—Cross-section of a hexagonal cell, showing how the currents rise in the
middle of each prism and flow down at the boundaries.
the boundaries. The contour of the surface of the liquid is exagger-
ated in the figure, but the relief is quite sufficient to permit the
structure of the circulating liquid to be observed by various optical
methods. Fig. 3 shows three examples of these structures in a
melted wax, taken under different conditions of temperature and
thickness and before the final steady state of circulation had been
attained.
A state of subdivision into irregular cells of from four to seven
sides is attained in a few minutes, even in a viscous oil. These
cells then join and subdivide repeatedly until finally, if the condi-
tions are constant, a perfect system of hexagonal cells is produced.
Even when the liquid is originally in motion, convection cells form
which show little or no trace of the original direction of movement
of the liquid as a whole.
ROBERT B. SOSMAN
bo
bo
bo
Waxes and oils were used for most of Bénard’s experiments,
because at his working temperatures of 100° and lower the requisite
conditions as to viscosity and low volatility could best be obtained
with these materials. By suspending in them finely powdered sub-
stances such as graphite or lycopodium, Bénard was able to show
visually and to photograph the cells produced, without the aid of
special optical devices.
As is to be expected, the dimensions of the cells depend upon the
thickness of the liquid layer, the temperature difference between
top and bottom, and the viscosity and temperature of the liquid.
Fic. 3.—Three examples of hexagonal cells formed in a melted wax, taken under
different conditions of temperature and thickness and before the final steady state of
circulation had been attained.
In a given liquid at a given temperature, and at a constant tem-
perature difference, the ratio of diameter to height is found to be
constant. Other laws governing the form and size of the cells were
found by Bénard, but it is unnecessary to discuss these in detail.
Following Bénard, Dauzére* in 1907 showed that crystallization
in salol and wax mixtures begins on the boundaries of the convec-
tion cells. A mixture of beeswax and stearin, on solidifying, sepa-
rates spontaneously into hexagonal prisms coinciding with the
original convection cells. In pure stearin, also, crystallization
begins at the corners of the cells. In every case the cells leave a
permanent record of their existence in the crystallized solid,
although in some cases the structure is quite invisible, and only
*C. Dauzére, Jour. physique, VI (1907), 892-99; VII (1908), 930-34; Assn.
franc. av. sci., 1908, pp. 289-96.
PRISMATIC STRUCTURE IN IGNEOUS ROCKS 223
appears when the wax is bent. Dauzére pointed out the strong
probability that certain symmetrical columns in Auvergne have
been due to convection in the basalt in which they are formed.”
In a horizontal sheet of molten rock which has come to rest after
extrusion or intrusion it is obvious that we have some at least of
the conditions necessary for the formation of convection cells. Hi
the cells succeed in leaving any permanent record of themselves
when the sheet solidifies, then subsequent contraction may bring
out the structure by cracking the rock along the boundaries of the
cells.
In general there are two ways in which the convection cells
might impress themselves on the crystallized rock. In the first
case the axes of the liquid convection cells and of the solid prisms
are coincident. Bénard found that a finely powdered substance
which is heavier than the liquid tends to gather on the bottom of
the vessel in little heaps situated on the axes of the convection
cells, giving an appearance from above of uniformly spaced round
spots. A floating substance, on the other hand, gathers along the
boundaries of the cells at the surface. A substance in suspension
gathers within the interior portion of the closed curves of Fig. 2,
so that the liquid shows transparent both on the axes and along the
boundaries of the cells. In a mixture, therefore, in which different
crystalline phases are separating at different temperatures, a Cer
tain amount of segregation is to be expected, and the solid prisms
will coincide with the convection cells.
In a substance which crystallizes as a unit, on the other hand,
whether it be a pure substance or a considerably undercooled mix-
ture, prisms may be formed without segregation. Bénard observed
that in spermaceti the crystallization began at the corners of the
cells. In pure stearin Dauzére found that crystallization beginning
at centers on the cell boundaries extended uniformly in all directions
until the growing cylindrical groups intersected to form prisms. It
is evident that in this case the prisms will not coincide with the
convection cells, but will nevertheless be symmetrical and regularly
spaced.
1C. Dauzére, Assn. franc. av. Sci.; 1908, pp. 436-38; also Longchambon, Bull.
Soc. Geol. Fr., XIII (1913), 33-38-
224 ROBERT B. SOSMAN
It is of interest to note that this convection-crystallization
hypothesis explains the original observation of Watt on the forma-
tion of columns in a cooling artificially melted basalt mass (see
p. 215). He accounted for his columns on the assumption that they
were produced by the mutual interference of radially.growing crystal
bundles, uniformly spaced in a horizontal plane. Why the crystal-
lization centers should be uniformly spaced he was unable to say.
The existence of convection prisms in the still liquid basalt provides
the missing link in the series of phenomena. Crystallization may
have begun at the axes of the convection prisms where a few early
separating crystals had collected, or at the corners as observed by
Bénard; in either case the crystallization centers would be uni-
formly spaced horizontally.'
If liquid convection is really the cause of all or any of the familiar
naturally occurring basaltic columns, then it is important to know
what criteria will help to decide the question in a given case.
Furthermore, a systematic examination of natural columns will
throw light on their history, whatever may be their mode of origin.
What are the important characteristics of a given occurrence which
should be observed in the field ?
CHARACTERISTICS OF CONTRACTION AND CONVECTION PRISMS
1. Altitude-——The original attitude of columns formed by con-
vection should be vertical, or very nearly so. Contraction columns,
on the other hand, are usually perpendicular to a cooling surface;
irregular conditions of cooling, furthermore, may cause them to
curve in a great variety of ways.
2. Dimensions—Convection columns should be much wider, in
proportion to their length, than contraction columns, which are
commonly very longand narrow. The columns at Murols described
by Dauzére are 1.5 to 2 m. wide and 5 to 1o m. high; those
measured by O’Reilly in the Giant’s Causeway are 0.4 to 0.5 m. in
width; the Causeway columns vary from 3 to 25 m. in total height.
Scrope describes columns near La Queuille as much as 5 m. in
diameter, and ro m. or less in height.2, The common contraction
«See Longchambon, Bull. Soc. Geol. France, XIII (1913), 33-38.
2 Volcanoes of Central France, London, 1858, p. 136.
PRISMATIC STRUCTURE IN IGNEOUS ROCKS 225
columns, on the other hand, are usually about o.2 m. or less in
diameter; their length is often 20 m. without a joint, and their
total length may be over 40m. It should be noted, however, that
the composition of the rock may have a considerable effect on the
size of columns under given conditions of cooling, the more salic
rocks forming larger columns than the more femic rocks.
3. Shape of cross-section.—Convection columns, if perfect,
should all be hexagonal. The more uniform the conditions have
been, the greater the proportion of hexagons; in any case, the
_ hexagonal sections will be in the majority. Seven-sided figures
will be common, produced by the trunkation of one angle of a
hexagon; pentagons will also occur frequently, by the elimination
of one side of a hexagon. But three- and four-sided figures will
be very rare. :
In contraction columns, on the other hand, pentagons are likely
to be the prevailing type, and four-sided figures are fairly numerous,
while hexagons become less important. This distribution of poly-
gons arises from the fact that a mass cracking under the stresses of
its own thermal contraction, although theoretically it should break
into perfect hexagons of equal area, actually tends to yield by the
formation of master-cracks which are then joined up by the forma-
tion of shorter cracks.* An example of thermal contraction prisms
on a large scale is seen in the soil polygons of Arctic regions; a map
of a set of these polygons, in a recent article by Leffingwell, shows
clearly the contraction-type fissures described above.
The relative frequency of polygons in some of Bénard’s artificial
convection cells,? in the Giant’s Causeway,‘ and in a columnar dike®
is Shown in Table I.
t “The rock may rather be said to be divided into numerous perpendicular fissures,
than to be prismatic, although the same picturesque effect is produced.”—Lyell,
description of Torre del Greco.
2E. De K. Leffingwell, Jour. Geol., XXIII (1915), 653.
3 The photograph used for this computation was one taken while the liquid was
cooling and the polygons were undergoing gradual changes, leading to the formation
of 5- and 7-sided figures. Under steady conditions of heat flow the cells were hexagons
almost without exception.
4J. P. O’Reilly, Roy. Irish Acad. Trans., XXVI (1879), 641-734.
5 A. Geikie, Ancient Volcanoes of Great Britain, illustration, p. 459.
226 ROBERT B. SOSMAN
Bénard’ has recently shown photographically the identity of
pattern between his convection cells and the cross-section of the
basalt columns of the flow of Estreys (Haute-Loire), and has also
pointed out the qualitative differences between this pattern and
that produced by contraction.
TABLE I
COMPARATIVE FREQUENCY OF POLYGONS (PERCENTAGE)
Grant’s CAUSEWAY
: 4 ARTIFICIAL COLUMNAR
No. or SIDES Gane Tee
Alonga 50-Meter Within
Line Measured Area
Sil will dised sare ee ° ° ° 5.2
ye aE a eI POR ene ks S GAG 230 Bu5 28.4
Biola nistnin/s = 0a cies erm sasaki ai 36.3 30.7 | 24.8 ASCE
CRIS On mirtcrets crs oc 45.2 Agen 50.5 20.7
Do shosdjs ose Ost aed een ae ee 12.7 -19.6 19.2 2.6
Steves SU a rhe 0.3 0.6 20 °
Total number counted. . 292 | 153 | 206 116
4. Frequency of angles——The angles of convection columns
should approximate to 120°, while contraction columns will have a
large proportion near go’. While the frequency of angles is a much
more logical criterion than the frequency of different polygons, it
is much more difficult to apply on account of the large number of
angular measurements to be made. Such a series was made with
great care by O’Reilly on the Giant’s Causeway, and I have sum-
marized his results in Table II. O’Reilly’s deduction from his
TABLE II
FREQUENCY OF ANGLES IN 206 POLYGONS OF THE GIANT’S CAUSEWAY
Range No. of Occurrences Range No. of Occurrences
64° to “Sse a meee 9 ETS 0) COWL 5 ww. 2 2383
E> gor tO! JSG ua ee 19 mac sOntOiras clas. cu 2363
$5430 HtO OS oc 563 T35; ee .to waste, eras
Q5° 30) tO Tose. tee, 1033 TAG BON EO TOS ocho 183
EOS” 30" LOVERS uae ees 215 ROGeGetO Esso. . Jee 5
measurements was that the form of the columns had been governed
by the principal angles of the constituent minerals of the basalt, a
view which has not met with general acceptance.
2 Compt. rend., CLVI (1913), 882-84.
PRISMATIC STRUCTURE IN IGNEOUS ROCKS 227
5. Difference in composition and texture between the axis and the
periphery of the columns.—Obviously, no variation whatever should
appear in contraction columns. If the columns are due to convec-
tion, however, there might or might not be a differentiation, depend-
ing upon whether the rock crystallized practically as a unit, or
whether it crystallized in stages which permitted of segregation in
the convection cells (see p. 223).
In 1914 Dr. H. S. Washington, of this laboratory, examined, in
the museum of the University of Catania, a polished section of a
column from one of the prehistoric basaltic flows of the Mount
Etna region, and observed no variation of texture across the
section. From their shape and manner of occurrence, these
columns at Etna would seem to be due to pure contraction, and
no variation is to be expected.
On the other hand, evidence is not lacking in geological litera-
ture of what seems to be a differentiation between the border and
axis of some basalt columns. Scrope, in his description of the vol-
canoes of central France, states that “occasionally (as for example
at La Tour d’Auvergne, in the Mont Dore), the columns show a
cylinder of compact black basalt within a prismatic case of lighter
colour and looser texture, a segregation of dissimilar matter having
accompanied the concretionary action.’’* Delesse? made in 1858
an interesting comparison of the density of the interiors and
exteriors of a variety of columns, the results of which are shown
in Table III. Here again a difference between the interior and
exterior is indicated in some of the columns, though not in all.
Unfortunately the source of the samples which showed small differ-
ences is not stated; it may be that they are columns of the narrow
contraction type. Delesse took care to assure himself that the
differences were real and were not due to weathering of the columns,
but it is not impossible that the differences are really due to weather-
ing, since he had not the modern microscopic facilities for examining
the individual minerals in thin section.
t Volcanos, 1862, p. 100. In speaking of ‘‘concretionary action” Scrope seems to
be referring to the rather vague hypothesis of columnar structure which prevailed at
the time (see note, p. 216).
2 Delesse, ‘Variations dans les roches se divisant en prismes,’’ Compt. rend.,
XLVII (1858), 448-so.
228 _ ROBERT B. SOSMAN
The regularity and symmetry of the columns of the Giant’s
Causeway suggests the convectional origin. It seemed of interest,
therefore, to examine a polished cross-section of one of these columns
for evidence of differentiation. Through the kindness of Dr. G. P.
Merrill, of the United States National Museum, a polished section
was cut for us from a Giant’s Causeway column in the Museum,
and also one from a column from near Bonn on the Rhine.
TABLE III
DIFFERENCE IN DENSITY BETWEEN AXIS AND SURFACE OF BASALT COLUMNS (DELESSE)
DENSITY
DIFFERENCE OF
DENSITY
Center Outside
Per Cent
rachyte, Icelande- eras 2.404 2.478 0.64
Mrachyte, isle Bonces. 424° eee 2.469 2.439 ea
Phonolite, Isle Lamlash.....:.... 2.541 2.500 1.26
Trap yAntrims 294 s2-4 ae aoe 2.QI1 2.857 1.85
Basalltc.2 2 ciscshie oes see 2.930 2.933 —o.10
Basalt: Saenotecticn = oer Gee eee 3.030 3.030 0.00
Basalticnk 2 As pac etn cee eee 2.924 2.916 One
Basalt: 5/2 8i\\acc ce cee ee 3.053 3.030 0.75
Basal tsi. hcl aks tae ge eee 3.044 3.008 1.18
The Bonn column was five-sided, with a maximum cross dimen-
sion of 18 cm. The cross-joint near which the section was cut
showed fracture lines radiating from one corner, and the joint passed
straight across. What appeared to be an inclusion about 16 mm.
in diameter showed near the center, and another of similar size
seemed to have been cut in two by one face of the column. A sharp
weathered zone 3 mm. wide showed clearly, but no other difference
between center and border appeared.
The Giant’s Causeway column was also five-sided, with a maxi-
mum cross-dimension of 37 cm. ‘The section was cut near the
convex side of a shallow ball-and-socket joint; the fracture of this
joint seemed to have radiated from the center, not from any point
of the border. The rough surface gave an appearance of finer
grain at the border than at the center. On the polished face, how-
ever, no such gradation was visible. There was a sharp weathered
zone 3 mm. wide, inside of which was a zone varying from 6 to
PRISMATIC STRUCTURE IN IGNEOUS ROCKS 229
22 mm. in width, with an ill-defined wavy border. This also may
have been due to weathering. Within the central eighth of the
area appeared 5 amygdules from 2 to 4 mm. in diameter, and filled
with a greenish opalescent mineral. Five others, from 1 to 2 mm.
in diameter, appeared in the remaining seven-eighths of the area,
none being closer than 25 mm. to the border. The section therefore
offers no decisive evidence of a differentiation, although meiesealy
different in character from the Bonn column.
6. Types of cross-jointing in the columns.—A differentiation due
to convection might be expected to affect the cross-joints of the
columns. The peculiar convex-concave or cup-and-ball joints are
seldom found in irregular narrow columns of the typical contraction
type, and might have some direct connection with a convection
structure. Another type of cross-jointing of columns is the “platy”
variety, which is sometimes very regular; its origin has not been
satisfactorily explained from the physicist’s standpoint.
Certain special peculiarities of the cross-jointing may also have
to do with the mode of origin of the columns. For instance, James
Thomson! observed that the symmetrical concave-convex joints of
columns from the Giant’s Causeway have their origin in a small
spot or knob which lies at or near the axis of the column, and differs
in texture and hardness from the rest of the rock; from this origin
the crack has spread outward, as shown by the radial fracture lines.
This same form of fracture has just been described above, as occur-
ring in the National Museum’s specimen from the Giant’s Cause-
way. Dauzére mentions the same peculiarity in the columns at
Murols, and compares it with the core (noyau) which forms in the
convection prisms of his wax-salol mixture.
There seems to be good foundation for the opinion that some
sort of original structure is responsible for the spheroidal weathering
of columns, and that it is not due solely to the rounding off of
jointed blocks by weathering, as some have claimed. ‘Thus Bonney
cites numerous examples of spheroids formed from columns which
showed no cross-joints whatever.2. Whether these latent spheroids
have any connection with the manner of growth of the column it is
t Belfast Nat. Field Club, Ann. Rep., VII (1869), 28-34.
2 Quar. Jour. Geol. Soc., XXXII (1876), 140-54.
230 ROBERT B. SOSMAN
as yet impossible to say. LLongchambon’ suggested that the super-
imposed spheroids are due to a breaking up of long liquid convec-
tion cells into a number of shorter ones, each with its own local
circulation, but there is no experimental evidence to support this.
7. Irregularities of faces of prisms.—Some basalt prisms show the
‘“‘feather-patterns”’ characteristic of fractures in homogeneous
solids. Their occurrence points strongly to a purely contractional
origin. They have been observed in the joint planes of slates, and
have been made the subject of an interesting study by Woodworth.”
SURFACE STRUCTURE PRODUCED BY INTERNAL EXPANSION
In addition to the prismatic structures produced by contraction
and convection or by convection combined with crystallization and
contraction, still another type needs to be considered, namely that
due to expansion.
The accompanying photograph of a polygonal structure in a
cement briquette (Fig. 4) is an illustration of the formation of this
structure by internal expansion. This sample, which was kindly
furnished us by Mr. A. A. Klein, of the Bureau of Standards in
Pittsburgh, was made from a cement which contained free lime;
this by its hydration and absorption of carbon dioxide from the air
has expanded and destroyed the briquette.
It is possible that the ““weather-crack”’ structure on the surface
of diabase bowlders is likewise caused by internal expansion.
Wherry? has shown that there is no visible difference in texture
underlying these weather-cracks. Expansion of the surface by
hydration has been assumed as the cause of the structure; but this
would produce compression in the surface, accompanied by the
formation of shells (as indeed often occurs), whereas the ‘‘weather-
crack”’ structure is one indicating tension. It is necessary for
hydration to proceed into deeper portions of the rock before tension
t Soc. Geol. France, Compt. rend. somm., 1912, pp. 181-83; Bull., XIII (1913),
33-38.
2 Proc. Boston Soc. Nat. Hist., XXVII (1896), 163-83. For an extended study of
these feather fractures in glass and metals see Ch. de Fréminville, ‘“‘Recherches sur
la fragilité; L’éclatement,” Rév. metallurgie, 1914; also Mallock, Proc. Roy. Soc., A,
LXXXII (1909), 26-20.
3 Loc. cit.
PRISMATIC STRUCTURE IN IGNEOUS ROCKS 231
is set up in the surface; the cracks then produced are soon widened
by solution. A photograph of an excellent example of this type of
structure in diabase is given in Fig. 5. Internal expansion may also
account for the prismatic surface structure of ‘‘bread-crust bombs,”
although this remains to be proved.
Fic. 4.—A polygonal structure in a cement briquette, caused by internal
expansion.
SUMMARY
From the physical standpoint, several types of prismatic struc-
ture in igneous rocks can be distinguished. The first and most
common is due purely to thermal contraction in the crystallized
rock; examples are numerous and familiar. A subordinate type
of contraction structure is produced when the contraction and
separation occur while the magma is still partly crystalline and
partly liquid; this type is illustrated by an occurrence in a diabase
sill in eastern Pennsylvania.
ROBERT B. SOSMAN
Jop[Moq asequip ¥ JO aov]INs ay} UO aINJONAYs ,, YovId-19y}9\\ ,,—'S “OI ci
PRISMATIC STRUCTURE IN IGNEOUS ROCKS 233
The second general type is produced by convectional circulation
of the magma while still liquid. The cells so produced persist until
solidification begins, and may leave a record in the rock either by
causing segregation in the cell walls and axes, or by originating
regularly spaced centers of crystallization. The experimental and
observational data on the occurrence of this type in igneous
rocks are suggestive, but cannot yet be said to amount to decisive
proof.
A third type of prismatic structure is produced by internal
expansion. It has been produced artificially, and is offered as the
explanation of the “weather-crack”’ structure seen in diabase
bowlders.
In the study of these structures, the following field observations
are those which will be of greatest interest in the further study of
the problem: (1) attitude of prisms, (2) their diameter and length,
(3) frequency of four-, five-, six-, and seven-sided polygons, (4) fre-
quency of angles (especially 90° and 120°), (5) variation, if any, of
composition and texture in the cross-section, (6) types of cross-
jointing (platy, concave or convex, spheroidal), (7) spacing of cross-
joints, (8) peculiarities of cross-joints (e.g., whether cracked from
center or from borders), (9) degree of irregularity in sides of prisms,
(10) other peculiarities, such as tapering, partial longitudinal joint-
ing, etc.
The primary object of this discussion is to call attention to the
possibilities of the prismatic structure of a given rock body as an
index of its conditions of formation. Quantitative data on col-
umnar structures are very scarce; yet quantitative measurements
must precede quantitative deductions. We wish to know the tem-
perature of the rock when it was intruded or extruded; its viscosity
when it began to cool and when it began to crystallize; the amount
and kind of gases which it released; if extrusive, the climatic con-
ditions under which it cooled; if intrusive, the properties of its
inclosing strata at the time of intrusion. These and other facts are
deducible only from the present properties of the rock, among which
its prismatic structure will prove of great importance.
Equally necessary with the field data are experimental studies
of the structures produced in a cooling magma under conditions
‘
g
234 ROBERT B. SOSMAN
that can be controlled and measured. Such experiments will
require the melting and handling of larger quantities than it has
been customary to use for laboratory experiments, but the diffi-
culties ought not to prove serious. Even in the absence of such
experimental data, much can be learned from a careful field exami-
nation of prismatic and columnar structures.
ELLIPSOIDAL LAVAS IN THE GLACIER NATIONAL
PARK, MONTANA!
LANCASTER D. BURLING
Geological Survey, Ottawa, Canada
The paper by Capps on “Some Ellipsoidal Lavas on Prince
William Sound, Alaska,” recalls to my mind a similar occurrence
which [ visited in 1907. The locality is now so accessible and the
flow is so clearly subaqueous in character that a brief description
of it may be of interest. Its outcrop appears in the ridge (Shepard
Mountain) northeast of Flattop Mountain, Glacier National Park,
Montana, and the features described are in that portion of the bed
which overlooks the Shepard Glacier. The lava, to which the name
Purcell lava has been commonly applied, interrupted the sedi-
mentation of a flat-lying, greenish argillite which forms the upper-
most part of the Siyeh formation of the pre-Cambrian. This
argillite lies in normal position, and the portions above and below
the lava bed are macroscopically identical.
The Purcell lava is approximately 150 feet thick on Shepard
Mountain and can be traced for miles to the southeast, north, and
northwest. It is composed of six or more successive flows, each
-of uneven and more or less ropy surface, separated by small and
more or less local accumulations of shale. The lower 25 or 30
feet of the flow is composed of a conglomeration of dense, homo-
geneous, spheroidal masses averaging 1 to 2 feet in diameter.
They preserve their shape in the lower layers, being separated
from each other by chert or drusy cavities, and many individuals
have displaced considerable portions of the mud upon which they
were rolled or shoved, even to the extent of complete burial. The
bottom of the flow is therefore exceedingly irregular. Toward the
top of this bed the individual spheroids yield more or less to the
‘Published by permission of the Deputy Minister of Mines. .
2 Jour. Geol., XXIII (1915), 45-51.
235
236 LANCASTER D. BURLING
pressure of their fellows, and they unite to form an upper surface
of moderate unevenness. The upper part of the entire flow is
composed of a bed about 20 feet thick, which, though massive in
character, is very porous. Vesicles are common near the base of
several of the individual flows in the lower portion of the lava.
On Mount Grinnell, to miles to the southeast, Finlay’ gives the
thickness of the lava bed as 42 feet, but does not mention the ellip-
soidal masses which Daly later describes from the same locality.”
Finlay records the discovery of five genetically connected dikes
on Flattop Mountain close to the localities where the ellipsoids
are present. Elsewhere, though the lavas reached the surface
through numerous widely scattered dikes, ellipsoidal structure has
not been recorded. This period of igneous activity has been
described’ as having genetically connected extrusive and intrusive
phases, and it is interesting to note that strata, upon whose upper
subaqueous surface lava was being extruded, should have been
able, at a depth of only 600 feet, to accommodate themselves to the
essentially contemporaneous intercalation, along single planes, of
intrusive sills scores of square miles in extent.
This flow seems to afford an excellent opportunity for determin-
ing the value of certain criteria for distinguishing (1) subaerial
from subaqueous flows, and (2) the top from the bottom of sub-
aqueous flows. Here the normal attitude of the flow and its includ-
ing sediments is unquestionable, and the bottom of the bed in which
the ellipsoidal structure is developed is far more uneven than the
top, an observation which lessens the importance of one of the
criteria advanced by Capps. Furthermore, the silting up of cracks
in the surface of the flow would seem more natural than the upward
penetration, into cracks several feet in height, of mud sufficiently
resistant to flatten the bases of individual ellipsoids. That the
latter is true for the Prince William Sound locality? merely illus-_
trates the difficulty of obtaining competent and unconflicting
criteria.
t Bull. Geol. Soc. America, XIII (1912), 350.
2 Memoir Geol. Survey Canada, No. 38, Part I (1912), p. 217.
3 Daly, ibid., pp. 218-20.
4 Capps, Jour. Geol., XXIII (1915), 40.
ELLIPSOIDAL LAVAS IN GLACIER NATIONAL PARK 237
So far as the Glacier National Park exposure of the Purcell lava
is concerned, the following criteria would seem to indicate the
bottom of a subaqueous flow: (1) discreteness of the basal spheroids
and their relative competence to resist mashing; (2) comparative
unevenness, with reference to the top; (3) the irregular displace-
ment of the underlying shale by the basal spheroids; and (4) the
presence of vesicles near the base of the individual flows. Criteria
indicating the top are: (1) the common ropy structure; (2) more
or less complete fusion of the individual spheroids; (3) comparative
evenness, with reference to the bottom; (4) silting up of hollows
in the top by strata whose laminae parallel those of the adjacent
strata; and (5) the absence of vesicles in the upper portions of
the individual flows.
The flow under discussion covers an area hundreds of square
miles in extent, and while its extrusive character has been recog-
nized by various observers, the ellipsoidal structure has only
been found at the localities described. It may have been sub-
aqueous in places, subaerial in others (the Siyeh argillites are
abundantly ripple-marked and sun-cracked in places), but many
lines of evidence seem to prove its subaqueous character at the
locality described, and indicate that ellipsoidal structure is a com-
petent criterion of subaqueous extrusion. —
THE ORIGIN OF RED BEDS
A STUDY OF THE CONDITIONS OF ORIGIN OF THE PERMO-
CARBONIFEROUS AND TRIASSIC RED BEDS OF
THE WESTERN UNITED STATES
C. W. TOMLINSON
University of Minnesota
PART II
CONDITIONS OF DEPOSITION OF RED CLASTIC SEDIMENTS:
MODERN TYPES
Seven distinct types of partly or wholly clastic modern red
sediments have come to the attention of the writer, some of which,
however, are closely related. The occurrence of each one of these
types and its application to the Red Beds of the western United
States is discussed in the following paragraphs.
Red clay of the deep-sea bottom.—This material is invariably very
fine-grained, it contains little or no terrigenous matter of any kind,
and it accumulates very slowly indeed, so that a thickness of it
comparable to the total thickness of shales in any series of the
western Red Beds is practically inconceivable. Nearly every part
of all the series included in the Red Beds group exhibits incon-
testable evidence of shallow-water deposition, while the oceanic
red clays are exclusively abysmal deposits. Such arguments could
be multiplied almost indefinitely; it is quite clear that deep-sea
red clay is not related to our problem in any way whatsoever.
Stream deposits derived from pre-existing Red Beds.—This type
of deposits is illustrated by the flood-plain deposits of the Red
River of the South, in Texas, Oklahoma, and Louisiana. This
type cannot be dismissed so easily, for there are yet in existence
masses of pre-Cambrian red sediments within the possible drainage
areas tributary to some of the areas of the Red Beds. One objection
to this source for the ferruginous matter of the Red Beds is that
there were other sources for the sediments in question, nearer than
238
THE ORIGIN OF RED BEDS 239
the pre-Cambrian series, and that much of the material of the Red
Beds is known to have been derived from other rocks.
Arkosic stream deposits.—These are illustrated by deposits of
limited extent in and downstream from the region occupied by
the Sherman granite of Wyoming, which weathers to a coarse
pink gravel, owing its color to a high content of undecomposed
pink orthoclase. It is obvious that much the greater part of the
color of the Red Beds is not due to pink feldspar; but in some of
the very arkosic sediments of the Cutler and Dolores formations,
and probably elsewhere, this is an element not to be ignored.”
Stream deposits deriving their coloring matter from ferruginous
residual soils.—The fourth type of modern red sediments is exempli-
fied by the continental portion of the deposits of the lower Amazon,
and by smaller deposits in some of the rivers of the United States.
Russell says:
Each grain [of sand in residual soils left by the decomposition of crystalline
rocks in the southern Appalachian Piedmont] is coated with a thin shell having
a brownish or red color. Prolonged washing fails to remove this superficial
coating, a fact which is well illustrated by the color of the sands deposited by
the streams of Virginia and the Carolinas in the regions underlaid by crystalline
rocks.?
Russell appears to assume that all of the ferric oxide produced
by the decay of the crystalline rocks of this area is attached to
grains of other minerals in this way. That which fills interstices
between grains of sand in the final deposit,3 as distinct from that
which occurs in coatings on the grains, probably persisted inde-
pendently, however, and was transported as a fine sediment like
clay.
The relation between surface weathering of the Piedmont
crystalline rocks and the color of the Newark clastics in the neigh-
boring areas, as developed by Russell, is very much the same as a
relation recently advocated by Beede* between weathering of lime-
t Cf. Whitman Cross, Telluride Folio (No. 57), Geol. Atlas of the U.S., U.S. Geol.
Survey, 1899, p. 2.
21. C. Russell, ‘“Subaerial Decay of Rocks,” U.S. Geol. Survey Bull. No. 52, 1889,
5 Wl
3 See p. 164, this volume.
4]. W. Beede, “Origin of the Sediments and Coloring Matter of the Eastern
Oklahoma Red Beds,” abstract in Bull. Geol. Soc. America, XXIII (1912), 723-24.
240 C. W. TOMLINSON
stones and the color of the Red Beds of eastern Oklahoma. He
Says:
The coloring matter is thought to have been derived from the solution of
the 7,000 or 10,000 feet of pre-Carboniferous limestone which formerly covered
the Arbuckle-Wichita Mountains and much of the surrounding region. The
solution of the limestone furnished optimum conditions for the oxidation of
its iron content, as it does at the present time in the limestone regions of the
Mississippi Valley, southern Europe, West Indies, and elsewhere. Moreover,
the solution of the pre-Carboniferous limestones and the conglomerates of the
Arbuckle-Wichita region now in progress produces a red residuum practically
indistinguishable from Red Beds sediments. ‘The red granites, red porphyries,
and other crystalline rocks of the region under discussion contributed their
shares of material to the Red Beds.*
The Red Beds of the Grand Canyon section are underlain by
the famous Redwall limestone, and limestones underlie the Red
Beds practically throughout the Plateau province and in the San
Juan region. Areas in Colorado of history similar to that of the
Arbuckle-Wichita region, in that highlands existed there after the
earlier Paleozoic limestones were deposited, and during Red Beds
times, may well have played the same part in the central Rocky
Mountain region that Beede assigns to the Arbuckle-Wichita
uplift in Oklahoma. The existence of such highlands is demon-
strated by the great conglomerates in the Colorado Red Beds.
Various other land-masses which contributed material to the sedi-
ments of the Red Beds’ may have been quite as efficient as the
Arbuckle-Wichita highlands in producing residual soils stained by
ferric oxide.
It is evident from the foregoing discussion that stream deposits
deriving their coloring matter from ferruginous residual soils are
probably of no little importance in the Red Beds, and may con-
stitute a major part of the series of sediments included under that
term.
Terrigenous marine clastics—The fifth type of modern red
sediments is illustrated by deposits in the Atlantic Ocean off the
mouth of the Amazon River.‘ This is an exceptional occurrence,
* Beede, op. cit.
* See pp. 244-245. 3 See pp. 245-246.
4 John Murray, Challenger Reboris: Deep Sea Deposits, 1891, p. 234.
THE ORIGIN OF RED BEDS 241
as most terrigenous red muds lose their color on entering the sea.
A vivid description of this process of loss of color in the case of
certain rivers in Nova Scotia is given by Dawson, as follows:
This harbour [Pictou] receives the waters of three rivers and several smaller
streams, which in times of flood carry into it large quantities of reddish mud,
which sometimes discolours the whole surface. This mud, with similar sedi-
ment from the shore of the harbour, is deposited in the bottom, and there
undergoes a remarkable change of colour. A portion of old mud recently
taken from the bottom is of a dark grey colour, and emits a strong smell of
sulphuretted hydrogen... . . The iron of the red clay has entered into
combination with sulphur, and this is probably obtained from the sulphates
contained in the sea-water, by the deoxidizing influence of decaying vegetable
matter . . . . which grows abundantly on the mud flats. ... . In some parts
of the deposit forming in Pictou harbour, the vegetable matter which caused
the change of colour is so completely decomposed that no visible fragments
of it remain.t
The chemical action of marine organic matter is summarized
by Clarke in part as follows: ‘‘ Decomposing organic matter reduces
the sulphates of sea-water to sulphides, which by reaction with
carbonic acid yield sulphuretted hydrogen. Bacteria also assist
in the process.’”
The interbedding of marine limestones with Red Beds shales
in the Texan section is consistent with an origin for the shales
similar to that of the semi-oceanic sediments from the Amazon
River. The interbedding of gray and green strata with red ones
in certain of the Red Beds series indicates an oscillation of domi-
nance between oxidizing and deoxidizing conditions, such as might
be caused at the margin of the sea or in the waters of an inclosed
basin by variations in the rate of sedimentation or in the abundance
of organic matter. The marine type of deposition of red sediments
is not to be neglected, therefore, in an attempt at reconstruction
of the conditions of origin of the Red Beds; though the complete
absence of marine fossils from other parts of this group of sediments,
together with independent proof of the continental origin of most
of the group, shows that the marine type cannot be of more than
subordinate importance.
tJ. W. Dawson, “On the Colouring Matter of Red Sandstones and of Greyish
and White Beds Associated with Them,” Quar. Jour. Geol. Soc. London, V (1848), 29.
2F, W. Clarke, “The Data of Geochemistry,” 2d ed., U. S. Geol. Survey Bull.
No. 491, 1911, pp. 136-137.
242 C. W. TOMLINSON
Deposits of desert lakes or playas.—For an example of the sixth
type of present-day red sediments, deposited under water in desert
lakes or playas, we turn to Chinese Turkestan. The following
description, by Huntington, relates to the northern extremity of
the bed of Lop Nor, near the southern base of the Kuruk-Tagh
or Dry Mountains: ‘Beyond the fatiguing plain of salt [dry bed
of the dwindled lake Lop Nor] we found easy traveling for a time.
A fantastic red plain, the soft, dry bed of an older expansion of the
lake, glittered with innumerable gypsum crystals.”
Here we have a recent deposit of gypsum (or, more properly,
selenite), in which the crystals presumably are imbedded in a red
clay or mud. The relations here described could be duplicated by
many minor deposits of gypsum in the Red Beds of the western
United States. Farther out toward the center of the lake floor
occur the purer non-clastic sediments, which in the case of Lop Nor
are described as salt beds. The coloring matter of the clays
probably was derived, as in the two preceding types of modern
red sediments, from the decay of rocks on the neighboring uplands.
Red dune sands.—The seventh and last type differs from all
the others in being an eolian deposit. Red dune sands are excep-
tional rather than the rule in the desert regions of today, but they
occur in sufficient abundance to warrant attention. Their most
striking occurrence is in the Nefood or Red Desert of North-
western Arabia. The following quotation is from Palgrave’s
narrative of a journey taken in 1862: ‘‘We were now traversing
an immense ocean of loose reddish sand, unlimited to the eye, and
heaped up in enormous ridges, . . . . undulation after undulation,
each swell two or three hundred feet in average height.’”
The extreme breadth of the Nefood is about 150 miles, its
greatest length about 400 miles.$
Huntington mentions ‘an almost absolutely barren area of
reddish or yellowish sand dunes, from ten to a hundred or more feet
‘Ellsworth Huntington, The Pulse of Asia (Boston and New York: Houghton
Mifflin Co.), p. 254.
2W. G. Palgrave, Central and Eastern Arabia (London: Macmillan, 1908), pp.
62-63.
3 See J. A. Phillips, ‘‘The Red Sands of the Arabian Desert,” Quar. Jour. Geol. Soc.
London, XX XVIII (1881), 110-13.
THE ORIGIN OF RED BEDS 243
high’? between Karakir and Keriya River, in the southern border
of the Takla Makan Desert, Chinese Turkestan. Some 40 or 50
miles farther north is the district described in the following passage:
ss . ridge after ridge of sand, fifty to one hundred feet high.
.... Their gently sloping backs to windward were gray with a
cover of rather coarse sand, while their steep fronts to leeward were
pale brick-red with the fine sand of the main desert.’”
_ There are in the Red Beds of the western states no sandstones
of this type of such great thickness as that of the Nefood sands,
yet the possibility must be recognized that there may be local
sandstone members of this origin in the series. A region dry
enough to admit of the production of great bodies of gypsum might
easily be transgressed by shifting sands; or the two types of deposi-
tion might exist side by side, as they do today in the region of
Lop Nor and Takla Makan. The coarsely cross-bedded sandstones
of the Chugwater formation along the eastern base of the Wind
River Range in Wyoming, for instance, will bear further inves-
tigation with this possibility in mind.
EVIDENCE OF FEATURES OTHER THAN COLOR AS TO THE CONDITIONS
UNDER WHICH THE RED BEDS WERE DEPOSITED
The wide range in grain shown by the Red Beds of various
parts of the West, and the varying quantity of non-clastic sedi-
ments in the group, show that a variety of conditions existed in this
region during the time the Red Beds were accumulating, as is
to be expected from the great extent of the group. What the
varying relations were will be pointed out as accurately as possible
in the following pages.
Evidence of conglomerates as to the sites of land-masses.—Con-
glomerates, by the pebbles which they contain, display more clearly
than other sediments the source of their component materials. We
can therefore determine with some confidence the sites of the land-
masses which gave rise to the Red Beds, where these are con-
glomeratic. In southeastern Oklahoma, Beede* has presented
facts to show that the lower Red Beds sediments were derived from
Ree Huntington, op. cit., pp. 183-84.
2 [bid., pp. 184-85. 3 Op. cit.
244 C. W. TOMLINSON
the Arbuckle-Wichita region. Near the border of the present
Arbuckle and Wichita mountains, limestone conglomerate and
conglomerate of crystalline rocks dovetail into Red Beds sediments
of finer grain. The limestone undoubtedly was derived from earlier
Paleozoic formations, and the crystalline fragments from more
ancient rocks, both of which are known to have been exposed in the
uplifted region just named. Increasing thickness of sediments
toward the mountains testifies to the same relation. To what
distance sediments from this isolated highland may have been
distributed is largely a matter of conjecture. The entire Red
Beds series thins northward from this area to the northern limit
of their outcrops in Nebraska, and in the same direction clastic
sediments give place in part to limestones: both of which facts
signify increasing distance from the source of terrigenous material.
The small outlier of Red Beds in central Iowa, which probably
is to be correlated with the Cimarron series of Kansas," is composed
chiefly of red shale and gypsum, likewise indicating relatively
clear-water conditions. It would be an unwarranted assumption,
however, to assume that the Kansas and Iowa Red Beds were
derived wholly from the Arbuckle highlands. The greater areas
of upland which probably existed in the region surrounding and
including the pre-Cambrian areas of Minnesota and Wisconsin
may have been important sources of material, as may also the
ancient Appalachian continent of the East; but it may safely be
said that their influence is not exhibited in the strata now available
for study, as the influence of the Arbuckle highland so clearly is.
Similar criteria may be applied to the great conglomerates of
the Fountain and Wyoming formations of the Front Range, and
to those of central and southwestern Colorado. The conglomerates
of the Front Range Red Beds and of the Maroon formation of the
Anthracite, Crested Butte, and Tenmile districts are made up
chiefly of fragments from pre-Cambrian crystallines,? which still
«Cf. F. A. Wilder, “The Age and Origin of the Gypsum of Central Iowa,” Jour.
Geol., XI (1903), 723-48.
2 See Whitman Cross, Pikes Peak Folio (No. 7), Geol. Atlas of the U.S., U.S. Geol.
Survey, 1894; G. K. Gilbert, Pueblo Folio (No. 36), 1897; and G. H. Eldridge,
“Description of the Sedimentary Formations,’’ Anthracite-Crested Butte Folio (No. 9),
1894.
THE ORIGIN OF RED BEDS 245
outcrop in wide areas in various parts of the ranges. The Maroon
conglomerates include also fragments of quartzite and limestone
from older sediments. The composition of these formations
renders it certain that their materials were not carried far from their
sources; it is therefore certain that there were highlands, and there
may have been mountain ranges of no insignificant relief in various
parts of Colorado during Red Beds time—which here probably
was included for the most part within the Pennsylvanian and
Permian periods.
The coarser beds of the Cutler and Dolores formations in south-
western Colorado show by their composition that they also were
derived very largely from igneous and metamorphic terranes.*
The studies of Cross? have shown that the northern part of the
San Juan region itself, as well as the neighboring Uncompahgre
Plateau, was exposed to erosion between early Cutler and Dolores
time—at or near the beginning of the Mesozoic era. This upland
may have furnished sediment to a considerable part of the plateau
province to the west and southwest. Cross is of the opinion that
the absence of the Red Beds on the Uncompahgre Plateau is due
to post-Dolores erosion; but the conglomeratic character of the
Red Beds in the San Juan Mountains demands that a source for
those sediments be found close at hand. In the absence of any
conclusive evidence that the Red Beds ever were deposited over
the plateau in question, it may be regarded at least provisionally
as the probable site of that source.
The sediments of the Plateau province, on the whole, do not
indicate mountainous topography in the vicinity; but their great
thickness (maximum more than 5,000 feet, excluding non-clastic
beds) calls for the existence of a land area contributing sediments
to this region for a long period of time. Such an area may well have
existed toward the south and southwest, in Mexico, southwestern
«See Whitman Cross and others, in the following folios of the Geol. Altlas of the
U.S., U.S. Geol. Survey: Telluride (No. 57), 1899; LaPlata (No. 60), 1899; Silverton
(No. 120), 1905; Needle Mountains (No. 131), 1905; Ouray (No. 153), 1907; Engineer
Mountain (No. 171), 1910.
2 Whitman Cross, “Stratigraphic Results of a Reconnaissance in Western Colorado
and Eastern Utah,” Jour. Geol., XV (1907), 648-49, 654-56.
3 [bid., pp. 648-49.
246 C. W. TOMLINSON
Arizona, and southeastern California, or farther north in the Great
Basin, where no sediments contemporaneous with those in question
are known to occur.t The absence of sediments between the
Mississippian and the Cretaceous in the El Paso quadrangle? in
western Texas may be due altogether to erosion following deforma-
tion at the close of the Jurassic period, but this gap in the record
makes it possible that land may have existed even here during Red
Beds times. |
Richardson has concluded from his studies of the Black Hills
Red Beds? that those sediments were derived chiefly from the
Rocky Mountain area to the southwest and west. West of central
Wyoming, the Red Beds group thickens, and the quantity of lime-
stone and gypsum in it diminishes, continuously westward across
the Idaho border, suggesting a source of sediments in that direction.
The great thickness of the group all along the Wasatch Range,
wherever it is exposed, extends this suggestion to include a con-
siderable land area trending north and south from southern Idaho
into central Utah.
Significance of non-clastic sediments~—The more important
limestone members of the Red Beds record the existence of exten-
sive bodies of clear and not excessively salty water during parts of
the Pennsylvanian period in central Texas, in the Plateau Province,
in the San Juan region, and in southeastern Wyoming; during
the Permian, in the region north and east of Great Salt Lake (in
the early part of the Permian, marine deposition throughout much
of Wyoming, prior to the initiation of Red Beds sedimentation
there), and in western Texas; and in the Triassic, in northeastern
Arizona.
«Cf. paleogeographic maps by the following authors: T. C. Chamberlin and
R. D. Salisbury, Geology (New York: Henry Holt & Co., 1909), II, 545; ILI, 3 and
62; W. B. Scott, An Introduction to Geology (New York: Macmillan, 1909), pp. 616,
662; Charles Schuchert, ‘“‘ Paleogeography of North America,” Bull. Geol. Soc. America,
XX (1909), Pls. 84-88 inclusive.
2G. B. Richardson, El Paso Folio (No. 166), Geol. Atlas of the U.S. U.S. Geol.
Survey, 1909.
3G. B. Richardson, ‘‘The Upper Red Beds of the Black Hills,” Jour. Geol., XI
(1903), 365-93.
THE ORIGIN OF RED BEDS 247
The extraordinary development of gypsum in the Permian
Red Beds deserves more than passing comment. In association
with salt, deposits of gypsum are interpreted as indicating aridity
of climate at the time of deposition, and of formation in at least
partially inclosed basins by the evaporation of bodies of water
not freely connected with the open sea.t. This occurrence of
gypsum, supported by independent evidences of continental origin
for the Red Beds, has been the one strongest influence in establish-
ing the idea that the red color itself is an indication of aridity.
The absence of gypsum from many series of Red Beds, and its
occurrence in series free from Red Beds, make it necessary to investi-
gate the two problems on their own independent merits.
Rock salt is of relatively rare occurrence in the group of sedi-
ments under discussion. Since the saturation point of gypsum in
aqueous solution is much lower than that for common salt, it is
logical to suppose that the deposition of gypsum unaccompanied
by rock salt signifies.a condition of aridity and of continuous or
' intermittent supply of normal sea-water or of fresh water such as
to maintain a degree of salinity more moderate, for example, than
that of Great Salt Lake at present, but sufficient to cause the con- _
tinued precipitation of gypsum. Such a condition might be kept
up by a limited or intermittent connection between the open sea
and the basin of deposition.
The relation of the gypsum and salt deposits of the West to
the Red Beds proper suggests a relation similar to the relation
between marine limestones and terrigenous sediments. The
Rustler dolomite and the Castile gypsum of the Texan portion of
the Pecos Valley give place northward to typical Red Beds with a
few interbedded strata of dolomite and gypsum. May not the
gypsum, as well as the dolomite, be but the complements of the red
clastic sediments, deposited in the clear central waters of an inland
sea, or in lagoons near or at sea-level but partly or wholly cut off
from the sea; while clastic sedimentation went on nearer the shores
and on river deltas or flood-plains yet nearer to the sources of
sediment ?
t Cf, Wilder, op. cit.
248 C. W. TOMLINSON
The clastics: minor structural features —Returning to the clastic
sediments, we may draw still further inferences regarding the con-
ditions under which they were deposited, from their structural
characteristics and mineral composition. Ripple-marks and mud-
cracks in the majority of Red Beds sections testify to the prevailing
shallowness of the water in which these sediments were laid down.
Mud-cracks repeated in layer after layer, as in some parts of the
Red Beds, mean complete emergence and at least partial drying,
after the deposition of each stratum and before that of the next
following. Shallow water means shifting currents, and these too
are recorded clearly by cross-bedding in most sandstones of the
series, and by rapid variation along the strike in the shaly members
as well. We do not have, in the clastic portions of the Red Beds,
and seldom do we find in the non-clastic members thereof, the
continuity of a single type of sedimentation over wide areas and
through long periods of time, which are to be expected in truly
subaqueous or marine deposits. Furthermore, imperfect assort-
ment, which is one of the universal characteristics of fluviatile
deposits, is the rule in the Red Beds. The sandstones are earthy,
the shales sandy, the conglomerates gritty, etc. Each of these
characteristics is suggestive of subaerial conditions, and the occur-
rence of all of them together in the same series, and widely dis-
tributed through that series, is conclusive testimony to such an
origin.
The clastics: mineral composition.—From the mineral composi-
tion of the clastic sediments we may infer something of the con-
ditions of weathering and transportation which preceded their
deposition. The high proportion of feldspar in many of the Red
Beds shales and sandstones indicates a preponderance of mechanical
disintegration over chemical decomposition. The abundance of
undecomposed mica flakes in most Red Beds confirms this inter-
pretation. ‘Transportation may precede complete decomposition
because of exceptional rapidity of disintegration, exceptional slow-
ness of decomposition, or both. Rapid disintegration may be
caused by such factors as high relief and great daily or seasonal
range of temperature; slow decomposition by low rainfall or low
temperatures. Low temperatures throughout the year explain
THE ORIGIN OF RED BEDS 249
the slowness of chemical decomposition in polar regions; aridity
explains it in the desert, where disintegration is accelerated by
great daily range of temperature; and disintegration is acceler-
ated on mountain peaks by all of the factors mentioned. Absence
of vegetation, which itself is dependent chiefly on climatic factors,
is unfavorable to rapid decomposition of rocks because of the
important part played by organic acids in the chemical processes
of weathering.
As we have seen, the occurrence of gypsum indicates aridity
and high temperatures, so that we may rule out the hypothesis
of Arctic conditions as applicable to the Red Beds. The coarse
conglomerates in certain parts of the Red Beds are indications of
high relief in certain areas and at certain times.
The occurrence of limestone conglomerate in the Red Beds
of the Arbuckle-Wichita region emphasizes the predominance of
disintegration over decomposition in that area, as limestone is one
of the most readily decomposed of rocks. If the limestone con-
glomerates of the Cutler formation were detrital, it would have the
same significance concerning the processes of the San Juan region;
but it has been interpreted otherwise.
Evidence supplied by fossils——It has been stated that marine
limestones. carrying abundant faunal remains occur in central
Texas interbedded with the Permo-Carboniferous Red Beds.
The significance of the relations found in this region is well sum-
marized by Chamberlin and Salisbury, as follows:
The oldest part of the Permian system (Wichita formation) indicates that
the critical attitude which characterized the surface farther east during the
Pennsylvanian period now affected Texas, for the beds are partly of marine
and partly of fresh-water origin. These beds are succeeded by a formation
of limestone (the Clear Fork) of marine origin, which overlaps the Lower
Permian. The Upper Permian (Double Mountain formation) which follows
indicates a reversal of relations, for much of Texas was again cut off from the
ocean, and converted into an inland sea, or into inland seas, in which the
phases of deposition common to such bodies of water took place. Occasional
beds of limestone with marine fossils point to occasional incursions of the sea,
while deposits of salt and gypsum point with equal clearness to its absence, or
to restricted conditions, and to aridity of climate.!
tT, C. Chamberlin and R. D. Salisbury, College Geology (New York: Henry Holt
& Co., 1909), p. 661.
250 C. W. TOMLINSON
The large and varied vertebrate fauna which has now been
described from the clastic members of the Red Beds series in various
parts of the Southwest' includes no forms requiring other than
a land or fresh-water habitat, with the exception of fish remains
in some of the marine beds just mentioned. In general, then, it
is true that the paleontological evidence corroborates the purely
stratigraphic and lithologic evidence for a continental origin for
at least the greater part of the Red Beds. In certain places and
at certain horizons the fossil remains, both plant and animal, are
sufficiently abundant and of such types as to eliminate the possi-
bility of extreme aridity as a continuously prevalent condition.
The bone beds and petrified forests of northeastern Arizona, for
instance, prove that during the time of deposition of the Shinarump
group,” at least, there was a water supply in that vicinity sufficient
to permit the support of abundant land life, both vegetable and
animal. It is possible, however, that this water supply was derived
from precipitation in a distant region, like the waters of the Nile
delta. In the underlying Permian, which contains more salt and
gypsum than the other members of the series in this district,
vertebrate remains are absent. The Permian of the neighboring
Kanab Plateau has yielded an extensive invertebrate fauna} sug-
gesting brackish-water environment.‘
Summary.—The most salient of the facts and inferences brought
out by the foregoing discussion of the significance of features other
than color as to the conditions of deposition of the Red Beds may
be summarized as follows: (1) rapid erosion on land-masses of
considerable relief; (2) decomposition not complete in advance of
transportation; (3) sediments diminishing in thickness and in
coarseness of grain away from sources of material, and clastic
« See especially various publications by S. W. Williston in the Journal of Geology,
1903-13.
2L. F. Ward, “Geology of the Little Colorado Valley,” Am. Jour. Sci., 4th
Ser., XII (1901), 401-13. On p. 405 is the following statement: “‘The Shinarump
constitutes the horizon of silicified trunks and there is no part of it in which fossil
wood does not occur in great abundance.”
3See C. D. Walcott, ‘The Permian aid Other Paleozoic Groups of the Kanab
Valley, Arizona,” Am. Jour. Sci., 3d Ser., XX (1880), 221.
4 Interpretation by Eliot Blackwelder (personal communication).
THE ORIGIN OF RED BEDS 251
sediments giving place to non-clastic in the same direction; (4) flu-
viatile deposition most important; (5) all deposits in relatively
shallow water, or subaerial; (6) oscillating marine and non-marine
conditions at edge, non-marine in most of region of deposition;
(7) moderate aridity long continued in some parts of the region
of deposition, alternating with less arid conditions in other parts.
These conditions coincide to a remarkable degree with those
inferred from the study of modern red sediments.
RELATION OF DIASTROPHISM TO RED BEDS SEDIMENTATION
It may well be asked at this juncture why it is that earlier
Carboniferous clastics underlying the Red Beds of Oklahoma and
other states are not similarly colored. The difference in color,
since this has been shown to be a feature dating from the time of
sedimentation,’ must be due to differences of some sort in the geo-
graphic conditions of the times when the successive series were
deposited. One of these differences is the emergence of the plains
of deposition. Another may be found in the fact that some, at
least, of the highlands from which the Red Beds derived their
materials were not in existence in the earlier part of the Paleozoic
era. The Arbuckle-Wichita uplift probably dates from the later
part of the Pennsylvanian period; and there may have been
mountain-building in Colorado at the same time, as the strati-
graphic relationships of the scattered Paleozoic sediments in that
state seem to indicate. Dr. Blackwelder’? calls attention in this
connection to the fact that the general trend of the Arbuckle-
Wichita folding is directly in line with the suspected areas in
Colorado. Local climatic changes influencing the type of sedi-
mentation may have been brought about by these changes in topog-
raphy. The general continental expansion of North America
from Pennsylvanian to Jurassic times leads one to expect extreme
types of continental climate, including aridity, the localization of
which would depend largely on the configuration of the continent.
The deposition of red sediments derived from ferruginous soils
means either the development of red soils and the transportation
of the material thereof without hydration, or the development of
t See discussion of this point, pp. 162-67, this volume.
2 Personal communication.
252 C. W. TOMLINSON
limonitic ferruginous soils and the dehydration thereof during
transportation. The development of ferruginous soils is the chief
prerequisite to the deposition of Red Beds of the western type.
The areas from which the Red Beds derived their materials
certainly included uplands, and in part at least they are known to
have been possessed of fairly rugged relief; they were therefore
in all probability the sites of more abundant rain than fell upon the
plains or delta flats upon which the Red Beds were in large part
deposited. The combination of well-watered highlands with less
humid or semi-arid lowlands furnishes the conditions for the devel-
opment of red soils, and at the same time provides for the trans-
portation and deposition of the sediments derived from them.
without extensive hydration or reduction of the ferric oxide con-
stituent during the transfer.
An unusually extensive development of red soils during the
time of deposition of the Red Beds might have been due, in some
part at least, to the higher proportion of oxygen inferred by
Chamberlin and Salisbury’ to have existed in the atmosphere at
this time.
SUMMARY
The several steps which have been followed in the interpreta-
tion of the color of the Red Beds, and the results obtained, may be
summarized as follows:
1. The ferruginous matter which gives the Red Beds their
color has been present in the series in very nearly its present dis-
tribution and arrangement since the time of sedimentation.
2. This material has suffered no extensive change of ferrous
to ferric iron, or vice versa, since the time of sedimentation; the
proportion and present distribution of these compounds in the
series were influenced most largely by the original distribution of
organic matter.
3. Changes in the degree of hydration of the ferric oxide in the
Red Beds since sedimentation probably have not been of great
importance; and hydration probably has been quite as active as
the reverse process during this time.
tT. C. Chamberlin and R. D. Salisbury, Geology (New York: Henry Holt & Co.,
1909), II; 665.
THE ORIGIN OF RED BEDS 253
4. The ferruginous matter of the Red Beds was transported
and deposited almost, if not quite, wholly as a mechanical sediment,
both independently and as a coating upon grains of other material.
5. The types of sediments probably most important in the Red
Beds group are stream deposits, submarine fluviatile deposits,
and playa deposits, all predominantly of red color, and all deriving
at least the greater part of their ferric oxide from ferruginous
residual soils. Of these types the first is by all odds the most
important.
6. The study of characteristics of the Red Beds other than
color bears out the conclusion stated in No. 5.
7. The inauguration and cessation of Red Beds sedimentation
probably were connected closely with climatic and topographic
changes involved in the orogenic history of the continent.
The colors which distinguish Red Beds from other series are
due to a combination of lithologic, topographic, and climatic fac-
tors in the regions of denudation and in those of deposition, which
have not been reproduced over so great an area in more recent
times.
It is apparent that, in accordance with Barrell’s view,’ ‘‘red
color in sediments is not in itself an indication of aridity’’; for
the material of red ferruginous soils may be transported and
deposited in regions of high rainfall, or even under the sea, with-
out change of color; and red soils themselves develop in regions
of heavy rainfall. But since the dehydration of the limonitic
material of non-red ferruginous soils, as well as the continuance
of the relatively anhydrous condition of the hematitic material of
red soils, is favored by aridity in the regions of transportation and
deposition, therefore red sediments should form a larger part of the
sediments of arid than of humid regions.
1 Joseph Barrell, ‘Upper Devonian Delta of the Appalachian Geosyncline,”
Am. Jour. Sct., 4th Ser., XXXVI (1913), 437.
THE ACADIAN TRIASSIC
SIDNEY POWERS
Troy, New York
PART III
STRUCTURE OF THE ACADIAN TRIASSIC
The Newark rocks in the Acadian area exhibit a monoclinal
structure, with a prevailing northwesterly dip, interrupted by
broad, low folds. The monocline is broken by numerous faults
with a small displacement and by occasional faults with a displace-
ment of hundreds of feet. The other areas of Newark rocks have
undergone deformation of a similar nature, but the direction of the
monoclinal tilting differs in the various areas. In the case of the
Connecticut Valley, the Pomperaug Valley (Connecticut), the Deep
River (North Carolina), and the Wadesborough (North Carolina)
areas, the dip is southeast, where as in all the other areas it is
northwest.
The two structural features, the folds and faults, will be treated
separately and finally some attention will be given to the theories
of origin of this structure.
FOLDS
The most important and the most conspicuous fold in the
Acadian area is that shown by the hook in North Mountain wHich
incloses Scots Bay. The point of the hook forms Cape Split, and
the back of the hook, Cape Blomidon. This syncline pitches down
on the north side and is cut off on the north by a fault shown in
cross-section DD, Fig. 28. The syncline is shown principally in
the North Mountain basalt which dips toward Scots Bay on all
sides of the Bay at angles of about 5°. Under the basalt flows the
Blomidon shale is seen following the erosional escarpment, on the
south side of North Mountain, around to Cape Blomidon, near
which point it disappears under the waters of Minas Basin, as
254
THE ACADIAN TRIASSIC 255
shown in Fig. 27. Above the North Mountain basalt comes the
Scots Bay formation, the youngest formation in the Newark group
of the Acadian area. The Scots Bay formation is exposed on the
south side of the Bay, as shown in Fig. 27.
The eastern extremity of Minas Basin, east of Economy Point
(the area shown in Fig. 23), also forms a syncline which has been
disturbed by faulting at various points. The beds of red sandstone
on either side of Cobequid Bay dip toward the bay at angles of
about 3°—-5° except where they have been tilted by faulting. This
gentle dip must simulate that of the strata when they were first
deposited in the slowly subsiding geosyncline.
A syncline, which is well shown in a shore section, is found at
Quaco, between West Quaco and Melvin’s Beach, on the north
side of the Bay of Fundy (see cross-section BB, Fig. 7). The
sediments of the Quaco section are readily identified by the Quaco
conglomerate in the center. This conglomerate is exposed on the
shore near Vaughan Creek with a dip of 30° to the north and again
a mile inland (northwest) with a corresponding dip to the south.
The syncline is cut off obliquely on the north by a fault in such a
way that the axis of the syncline is shown in the shore section near
Melvin’s Beach, but the Quaco conglomerate of the northern limb
does not reappear.
At Split Rock a low anticline is shown, at Martin Head a syn-
cline, and at Waterside an anticline and the adjoining syncline.
In each of these cases the folds are cut off by faults. The folds
are at a low angle with broad arches or troughs.
Cape d’Or shows a small syncline in the basalt flows where the
basalt ridge turns, from its east-west course, to make the Cape on
the south. Horseshoe Cove has been formed at the axis of the
syncline. The basalt is also faulted as is shown in Fig. 12.
Everywhere in the sea-cliff exposures there are minor flexures
in the Acadian Triassic, both in the sediments and in the igneous
rocks. In Fig. 19, an example of the folds in the sediments west
of Five Islands is given. In the North Mountain basalt, gentle
folds are shown at Scots Bay, where the Scots Bay formation is
preserved in synclines (Fig. 29), and at Digby Gut, where a long
syncline is shown at Victoria Beach.
256 SIDNEY POWERS
FAULTS
The disturbance at the close of the Newark sedimentation threw
the rocks of this group into fault-blocks with a monoclinal tilting
toward the northwest. With such a structure, the major faults
would tend to assume a northeast-southwest trend, and some of the
more important faults should bound the formation on the north
and northwest.
The faults at the margin of the Triassic area are confined to
the northern and western sides. ‘Thus the basalts of Grand Manan
are faulted down on the west side, while the pre-Triassic rocks on
the east side of the island are probably tilted up. The older forma-
tions against which the basalts were downthrown have since been
eroded away, because they were less resistant than the basalts, and
Grand Manan Channel has been formed in them.
The northern and northwestern sides of the Triassic areas at
Split Rock, Quaco, Martin Head, and Waterside are all dropped
down as fault-blocks against older rocks. At Martin Head the
pre-Cambrian rocks form Martin Head itself, which is south of
the exposure of the Triassic sediments. This exposure of older
strata may be explained either as a horst or as the basement upon
which the southern limb of the Triassic syncline rests. The latter
view is favored, making the Triassic and the exposure of pre-
Cambrian part of one fault-block, with a fault south of the pre-
Cambrian. There also appears to be a minor fault in the axis of
the Martin Head syncline.
The fault of greatest displacement in the Fundy region is the
Cobequid fault (shown on the general map of the region), which
stretches from West Advocate, north of Cape d’Or, to a point
northeast of Truro, a distance of go miles. On the north side of the
fault is the Cobequid group of sedimentary and igneous rocks which
composes the Cobequid Mountains. On the south side of the fault
are Triassic sandstones at West Advocate and Advocate Harbour,
and Pennsylvanian rocks east of Advocate Harbour. The displace-
ment of this fault is probably 2,000-3,000 feet.
South of the Cobequid fault is another east-west fault which
bounds the Triassic on the north from Cape Sharp to the Chiganois
River (northeast of Truro). The displacement of this fault appears
THE ACADIAN TRIASSIC 2
to be greatest on the west, with a downthrow of 1,500 feet or less.
_ Parallel to this fault is another at Clarke Head which has brought
the Triassic down on the north against older rocks on the south,
forming a small graben shown in Fig. 17. All the rocks at Clarke
Head are intensely faulted.
The remnants of North Mountain basalt at Cape Sharp and
at Partridge Island appear to be faulted off on the south side.
The throw of this fault is uncertain in direction, but it may be a
continuation of the southernmost fault at Clarke Head.
The exposure of North Mountain basalt at Cape d’Or exhibits
several faults in a north-south direction, as shown in Fig. 12. The
end of Cape d’Or is probably on an east-west fault line. This
same fault may extend eastward.
The Five Islands region exhibits complex block-tilting with
blocks of relatively small size. Besides the fault bounding the
Triassic on the north, and the Cobequid fault farther north, an
east-west fault is shown at Gerrish Mountain (Figs. 20, 22). The
Five Islands are each separated by faults and are each tilted in
different directions. These faults on the north become lost in a_
greatly slickensided region shown in detail in Fig. 21. The slicken-
sided surfaces are usually vertical and have a north-south direction.
The major movement appears to have been in a horizontal plane,
but the stratification shows that there also has been vertical move-
ment. Many other north-south faults are shown along the shore
from Clarke Head to Five Islands, and a typical section is shown
in Fig. ro.
Near Lower Economy a strike (east-west) fault brings the
Triassic down into contact with a mass of Pennsylvanian strata
on the north on which the Triassic rests unconformably.
The hook of North Mountain, at Cape Split, is cut off by a
northeast-southwest fault which gradually cuts across this limb
of the Scots Bay syncline.
North Mountain is composed of basalt flows tilted to the north-
west so that an erosion escarpment is produced on the south side
ef the mountain and a gentle dip-slope on the north side. The
sea-cliffs on the north side are never very high for this reason.
With a continuation of the dip-slope, the erosion top of the flows
258 SIDNEY POWERS
appears to extend under the Bay of Fundy. The coast charts do
not show any pronounced submarine ridges parallel to North
Mountain, such as some authors have referred to, and therefore
there is a lack of evidence of any major fault parallel to North
Mountain. Moreover, no geological structure under the Bay oi
Fundy appears to be deducible from the submarine topography.
Cross-faults in North Mountain are readily shown by offsets
in the ridge of basalt flows because the flows are dipping at a low
angle northwest. The offsets are at Digby Gut, Bay View, Gulli-
ver’s Cove, Petit Passage, Grand Passage, and southwest of Brier
Island. The line of these faults is north-south. The displacement
of the flows by these faults, with the exception of the first and last
faults, is to the north on the west side of the fault. These offsets
are shown on the accompanying general map of the region. The
offset at Digby Gut is shown on Fig. 30, and that southwest of
Brier Island is shown by the position of a short submarine ridge
on the coast chart.
As shown by Daly" and by Haycock,? these fault lines across
North Mountain, and also the depressions at Parker Cove and
Sandy Cove were occupied by rivers at the time that the Summit
peneplain was being developed over the region. When the pene-
plain was uplifted the rivers became rejuvenated and persisted in
their courses until the present valleys were cut. Headward erosion
up the valley which is now St. Mary’s Bay diverted the streams
flowing across the basalt south of Bay View, and the more rapid
erosion in Digby Gut caused the abandonment of the Bay View and
Parker Cove valleys.
THEORIES OF ORIGIN
The faults which traverse the rocks of the Newark group are of
deep-seated origin, extending into the older formations. The
character of the underlying formations varies with the different
areas. Thus the Acadian Triassic is underlain in part by Carbonif-
erous folded sediments, in part by Silurian and Devonian slates and
tR. A. Daly, “The Physiography of Acadia,” Bull. Mus. Comp. Zool., Harvard
College, XX XVIII (1901), 92.
2 E. Haycock, “Records of Post-Triassic Changes in Kings County, Nova Scotia,:’
Trans. N.S. Inst. Sci., X (1900), 297.
THE ACADIAN TRIASSIC 259
Devonian granite, and in part by pre-Cambrian slates (the Meguma
series) and other metamorphic rocks (the pre-Cambrian complex
of New Brunswick). The Connecticut Valley area is underlain
by gneisses and schists, the New Jersey area by gneisses and some
Paleozoic sediments, and the Richmond area by gneisses and
granites. A theory which accounts for the structure of the Newark
beds must therefore suit the various basement rocks.
Davis,’ in studying the Connecticut area, reached the con-
clusion that the origin of the monoclinal fault structure was the
slipping of blocks of the underlying crystalline rocks on each other
along cleavage planes. As pointed out above, although the Con-
necticut area is underlain by gneisses and schists, the other Newark
areas are not. Suitable cleavage planes would therefore not be
expected in the other areas.
In the Minas Basin region, the crystalline rocks are several
thousand feet below the base of the Triassic. Furthermore, the
planes of slipping in these crystallines are parallel to the main struc-
tural lines of the formation. These lines run at an angle to the
axis of Minas Basin, as is seen In the nearest exposures of the
crystallines (the Meguma, or Gold-bearing series). The theory
proposed by Professor Davis does not seem, therefore, to apply to
the Acadian area.
Hobbs? considers that Professor Davis’ theory does not suit
the facts in the Connecticut Valley or in the Pomperaug area.
For the latter area, Hobbs proposes another theory to account for
the peculiar system of quadrangular block-faults. As this detailed
faulting is not typical of all the Newark areas, the theory is of
limited application.
Professor Barrell’ has recently ascribed the origin of the Con-
necticut Valley Triassic area to the gradual development of a fault
on the east side of the geosyncline, contemporaneously with the
tW. M. Davis, “The Structure of the Triassic Formation of the Connecticut
Valley,” U.S. Geol. Surv., 7th Ann. Rept., 1888, pp. 486-89.
2 W. H. Hobbs, ‘‘The Newark System in the Pomperaug Valley, Connecticut,”
U.S. Geol. Surv., 21st Ann. Rept., Part 3 (1901), pp. 122-33.
3J. Barrell, “‘Central Connecticut in the Geologic Past,” Proc. Wyo. (Penn.)
Hist. and Geol. Soc., XII (1912).
260 SIDNEY POWERS
filling of the basin with sediments. This fault is supposed to have
been initiated after sedimentation commenced, and to have increased
in displacement with the accumulation of the sediments.
In the Acadian area a corresponding fault is found on the north
and west, but there is no evidence that this fault developed until
sedimentation ceased. No completely satisfactory theory to account
for the structure has yet been presented.
IGNEOUS ROCKS
DISTRIBUTION
A description of the igneous rocks in each locality has been
given in the description of the general stratigraphy of the region,
and therefore merely a summary is attempted here. The flows
at Cape d’Or have been especially studied, and will be considered
in a separate paper by Professor Alfred C. Lane and the writer.
All of the igneous rocks associated with the Acadian Triassic
are of a basaltic composition. From the form of occurrence, they
are grouped into dikes and flows. According to the time of forma-
tion, they are classified as the Five Islands volcanics and the North
Mountain basalts. Dikes are so rarely exposed that it is necessary
to consider the rocks from the point of age, rather than form.
In Nova Scotia, outside of the Triassic area there are some dia-
bases and basalts which are probably of Triassic age. At Cheverie,
near the Avon River, there is a sill of diabase intruding Pennsyl-
vanian. strata." Again, in Guysborough County, near Guys-
borough, Fletcher has mapped on the sheets of the Geological
Survey of Canada masses of diabase cutting the Union-Riversdale
series. The nature of these masses is described by Fletcher? as
partly amygdaloidal, partly dioritic.
Dikes of Triassic age occur in a number of places between Nova
Scotia and the Connecticut Valley. The large majority of them
are of diabase composition.
« Verbal communication from Mr. W. A. Bell, of the Geological Survey of Canada.
2H. Fletcher, Geol. Surv. of Canada, Annual Report, 1886, pp. to1-3 P; also
Geol. Surv. Canada, Maps, Nova Scotia, Nos. 30, 31, 35, 36.
THE ACADIAN TRIASSIC 261
FIVE ISLANDS VOLCANICS
Under the heading Five Islands volcanics are included the tuffs,
agglomerates, and basalt flows in the vicinity of Swan Creek and
the Five Islands.. The thickness of the volcanics is estimated as
at least 350-400 feet. One associated dike is exposed at Gerrish
Mountain.
The Gerrish Mountain diabase dike is almost vertical and
about 20 feet or more in thickness. The diabase shows marked
columnar jointing, the columns being rather short and largely
horizontal or dipping at a low angle to the horizontal. The dike
is connected with the basalt flow which caps the sandstones of
Gerrish Mountain, and it has evidently furnished the material for
this flow and perhaps for a large part of the other igneous rocks
for the vicinity.
The basalt flows associated with the Five Islands volcanics
are found at Gerrish Mountain, on four of the Five Islands, on
Two Islands, and at Portapique Mountain (east of Gerrish Moun-
tain). It is noteworthy that the relation of these flows to the
agglomerates is unknown, and that there is no proof that they are
not connected with the North Mountain basalt instead of with the
Five Islands volcanics. The structure of these flows is in large
part columnar, and the base and the top of each individual flow is
marked by amygdaloid. The basalts are the usual fine-grained,
dark-gray, heavy rocks composed of augite and plagioclase with
accessory amounts of magnetite and occasionally olivine. A more
detailed petrographical description will be given below for the North
Mountain basalt, which will apply equally well to these flows.
Only one flow is exposed in Gerrish Mountain. This has a
thickness of over 75 feet. Three flows are exposed on the north
side of Moose Island, the upper one being agglomeratic. A portion
of a single flow is exposed on Diamond Island and on Long Island.
Two flows are seen on Pinnacle Island. The northern of the Two
Islands consists of three flows, the southern of probably only one.
The base of the series of flows is exposed on the eastern side of
Moose Island and on Gerrish Mountain. Under the amygdaloid
which marks the base of the flow is a layer of green ash 2-3 feet in
262 SIDNEY POWERS
thickness. A similar ash-bed is exposed west of Swan Creek under
the agglomerate flow mentioned below. The thickness of the flows
on Gerrish Mountain may be considerable, as the basalt covers
a large area.
The agglomerate beds, with associated tuffs, are exposed from
Greenhill eastward to Five Islands, in disconnected areas. The
relation of these remnants of flows and volcanic ejectamenta to
the sandstones is a problem only partly solved because of the faulted
contacts, with possibly minor thrust-faults, and the landslides which
are especially abundant in the tuff. The tuff underlies the agglom-
erate in most cases. The thickness of the tuff varies from a few feet
to 50 feet, and that of the agglomerate flows from 20 to 150 feet or
more. Exposures show that the agglomerate is overlain by red
sandstone, and is therefore older than the North Mountain basalt.
The agglomerates consist of a mass of angular fragments of
basalt and amygdaloid in a dark-green matrix of a basaltic com-
position. The exact character of the matrix is difficult to determine
because it is everywhere so badly weathered that a solid specimen
could not be procured. The field evidence, however, indicates that
this matrix is in part tuffaceous and in part a normal basalt. At
the sides of some of the masses of agglomerate are blocks of angular
basalt and amygdaloid imbedded in a red sandstone matrix, showing
that the breccia was either blown out into the area where sandstone
was being deposited, or washed out from a bed of tuff and breccia.
The cross-cutting contacts at one side of the masses of agglomerate
in two instances give them the appearance of intrusive bodies
rather than of flows. If the agglomerates are intrusive, rather
than extrusive, they probably fill volcanic necks.
NORTH MOUNTAIN BASALT
Under the term North Mountain basalt, used in a generic sense,
are included the basalt flows of Grand Manan, Isle Haute, Cape
d’Or, Cape Sharp, Partridge Island, and North Mountain. The
series of flows at these localities are correlated either for structural
reasons or because they are underlain by shale correlated with the
Blomidon shale.
THE ACADIAN. TRIASSIC 263
In each locality there are several flows, indicating successive
extrusions within such a short time of each other that no sediments
were deposited between the flows. It is impossible to state whether
any single flow originally covered the geographical area over which
the remaining exposures indicate that the formation once extended.
The Palisade diabase formes one sill too miles long on the out-
croping edge, while North Mountain is 120 miles long. In the
former case the igneous material was intruded at some distance
below the surface and had to push up this great weight of rock,
which, however, acted as a blanket over the feeder. In the latter
case the igneous material was extruded at the surface, with no
roof to sustain, but the feeders were constantly subjected to the
great heat loss by radiation at the surface, which would tend to
freeze them up.
Dikes associated with the North Mountain basalt are rare.
Several were reported on Grand Manan by Bailey,’ but they were
not observed by the writer. The largest of these is 50 feet wide,
and occurs at Flag Cove, near Swallow-Tail Light.
Other narrow dikes occur on the south side of Scots Bay, just
east of the Scots Bay formation exposures. These dikes cut the
basalt within 25 feet of the top of the upper flow. From the other
exposures of this flow it is judged to be at least roo feet thick, and,
if so, it is quite evident that the dikes cut the upper flow and are
not the feeders. With the dikes are many fissures filled with vein
material which is seen under the microscope to consist largely
of silica stained red with hematite. The width of both the veins
and the dikes varies from one to ten inches, and in the field they
look very much alike.
In thin-section the dikes are seen to consist of a very fine-grained
diabase, greatly altered and stained with limonite. The rock is
similar to that of the flows near the center, but shows some glass.
From the field evidence of the dikes and veins side by side in the
upper part of this thick flow, and from the microscopic evidence,
it is concluded that the dikes were formed from the basalt of the
upper flow after the crust of the flow had solidified and while the
L. W. Bailey, Geol. Surv. Canada, Report of Progress, 1870, pp. 216-21.
264 SIDNEY POWERS
center of the flow was still liquid. The crust appears to have
become fissured, with some of the fissures reaching down to the still
molten rock, and other of the fissures having no great depth and
therefore being filled with quartz from above at a later stage.
The structure of the flows is similar to that of all basalt flows.
The individual sheets are clearly distinguished by a relatively
thin amygdaloidal base and a relatively thick amygdaloidal top.
Flows composed entirely of amygdaloid were observed only at
Cape d’Or. The basalt is closely jointed and columnar joining
is frequently developed. The angle at which the columns and
planes between the sets of columns stand with respect to the vertical
and horizontal, respectively, indicates the dip of the flow. Faulting
in the sheets is frequently obscured by jointing.
In North Mountain, from Cape Blomidon to Cape Split, and
along the Victoria Beach shore of Digby Gut, the thickness of the
flows may be estimated. A partial section is exposed at Sandy
Cove and at Freeport, on Long Island, and at Tiverton, on Brier
Island. In most of the sections the lowest flow is the thickest,
and at the top of the series are several thin flows.
The section from Cape Blomidon to Cape Split shows two and
probably three flows, each with an estimated thickness of 150-300
feet. The top of the upper flow is exposed around the edge of Scots
Bay. It exhibits the small folds into which all the basalt flows
have been thrown. No other sections of the North Mountain
basalt are exposed until Digby Gut is reached, because the sea-
cliffs are low and expose only the upper flow or flows.
At Victoria Beach the best section is found. There is some
doubt if the lower flow, as here estimated, is not composed of
two separate flows, but the microscopic examination of slides made
from the first exposures above and below the blank in the section
indicates a coarseness of grain which characterizes the center of a
thick flow. Erosion has probably removed several flows from the
top of the section. The section consists of:
Top. Six flows 2-45 feet in thickness...... 160+ feet
Bases (Main flow’ :.:rcd Ss .tneete ts eae 600+
The upper flows of the Victoria Beach section are absent from
the exposures at the end of Digby Neck. They have either been
THE ACADIAN TRIASSIC 265
removed by erosion or were never deposited there. The thicknesses
of the portions of the flows remaining between the waters of
St. Mary’s Bay on one side and the Bay of Fundy on the other are
estimated as:
Sandy Cove Tiverton
(Ujoyovere wilon s's\ais Seeeeadinin UBI6 Wor 300+feet 150+ feet
MO werploware Mia ctje cic « oluscsr 3 ths TSO ie te (Satie
On Grand Manan the section is quite similar to those given
above. The number of thin flows on the top of the series was not
counted accurately. The section is:
Top. Ten(?) thin flows averaging 10-15 feet in
AV EKTIESS Naty nic eres efits august senenecey Set 100 feet
SCEOMAPMOW asl eas Monta cemenns Bee)
Base ues tnt Ow ar enee a slvars/ a) on eiclicveus beleuclietn ces sole ASO ts
The number of flows exposed on Isle Haute is unknown. The
section at Cape d’Or consists of 5 flows, of which the lower one
(556 feet) is the thicker. At Cape Sharp and at Partridge Island
two flows appear to be shown.
Only one petrographic description of the basalt of North
Mountain has been published. On account of the similarity of
the basalts associated with the Newark group little attention has
been paid to those of the Acadian area.
The basalt is a dark-gray or dark-greenish fine-grained rock
composed of plagioclase feldspar and augite with accessory amounts
of magnetite, olivine, and glass. The feldspar is a labradorite,
varying slightly in composition. The texture of the rock is ophitic,
laths of feldspar inclosing augites, or masses of augite inclosing
small feldspar laths. Chlorite, magnetite, limonite, hematite,
and serpentine are present as alteration products.
The proportion of glass to crystalline matter, of labradorite
to augite, and the presence of olivine each depend on the proximity
of the section to the top or bottom of the flow. The top of the
flow is always quickly chilled in contact with the atmosphere, and
solidifies with a large amount of glass and a large number of gas
cavities. These cavities later become filled with quartz, calcite,
1\V. F. Marsters, “Triassic Traps of Nova Scotia,” Am. Geol., V (1890), 140-43.
266 SIDNEY POWERS
or some other mineral to form amygdules. At the base of the flow,
rapid chilling also takes place; less glass is developed, but well-
crystallized magnetite is found. Alteration, however, soon com-
mences in the base of the flow because of the reaction of heated
waters on the basalt.
The glass, characteristic of the top and the bottom of a flow,
frequently contains most of the feldspar in laths already formed,
showing that the feldspar had commenced to crystallize before the
augite. In other cases the glass is accompanied by both augite
and feldspar. The glass always has a cloudy appearance.
Gravitative adjustment takes place in all flows which are
sufficiently thick, and which remain hot sufficiently long for a
movement of the crystallizing magma to take place without
being recorded in flow structure. As in the case of the Palisade
sill, olivine tends to form near the base of the flow and in the quickly
chilled top.
Gravitative differentiation is also shown in the relations of the
labradorite to augite. The augite settles toward the base of a
flow as in the case of a sill, and the feldspar rises.
The chemistry of the Cape d’Or flows will be treated in a sep-
arate paper, but it may be stated here that those basalts show a
normal composition, averaging about 52.5 per cent silicia, 14.3
per cent alumina. 9.8 per cent lime, 2.5 per cent soda, and 1 per
cent potash.
Rosiwal measurements on thin sections from the center of a
556-foot flow show a mineralogical composition of 40 per cent
plagioclase feldspar, 56.5 per cent augite, and 3.5 per cent iron
ores.
All the basalts show more or less alteration and disintegration
except where rapid marine erosion exposes fresh rock. The
amygdaloid, even where fresh, is always altered. In the drill-
cores at Cape d’Or, the same character of alteration was shown in
each amygdaloidal layer. A certain amount of hematite, with
limonite, is developed, giving these rocks a reddish color.
Veins are very common in the dense basalts as well as in ithe
amygdaloids. The veins are formed of jasper or quartz, with
either reddish (hematite) or greenish (malachite or chlorite) walls.
THE ACADIAN TRIASSIC 267
ORIGIN
The basalt unconformity of the Acadian Triassic always shows
upturned and beveled rocks overlain by Newark sandstones or
conglomerates with bedding parallel to the underlying erosion
surface. This fact indicates that the Newark sediments were
deposited on a peneplain, as has been found the case in the
Connecticut? and Richmond? areas.
On this peneplain, an orographic basin was formed, and into
the geosynclinal area sediments were brought from all sides. An
equilibrium between the rate of sedimentation and of subsidence
_of the geosyncline appears to have been reached when the Blomidon
shales were deposited at the top of the Annapolis formation.
The Wolfville sandstone at the base of the Acadian Newark
shows red sandstones and occasional conglomerates and shales,
in general evenly bedded. ‘The pebbles in the conglomerates are
stream-worn, but are frequently subangular. The character of the
Quaco conglomerate has been sufficiently treated. The Wolfville
sandstone indicates stream transportation, with deposition in
flood-plains, and perhaps in past in broad alluvial fans.
The Blomidon shales are generally evenly bedded, but show
occasional ripple or current marks, and rarely mud cracks. The
presence of Estheria indicates temporary bodies of water. Flood-
plains of mature rivers would furnish the necessary conditions for
the deposition of shales, with cut-off lakes in which the crustaceans
could live.
The red color of the Annapolis formation evidences long oxida-
tion of the iron during transportation and deposition. The white
or gray color indicates a lack of hematite, and the green color is
caused by the presence of chlorite.
The climate during the deposition of the Annapolis formation
was apparently hot and dry, with occasional floods. The presence
of calcite in nearly all the sediments, and the scarcity of arkose,
tW. M. Davis, U.S. Geol. Surv., 18th Ann. Rept., 1898, p. 20.
?N.S. Shaler and J. B. Woodworth, U.S. Geol. Surv., roth Ann. Rept., 1899,
p. 408.
3 J. Barrell, “Relation between Climatic and Terrestrial Deposits,” Jour. Geol.,
XVI (1908), 159-90, 255-95, 363-84.
268 SIDNEY POWERS
and of plant and animal remains, all favor long oxidation of the
sediments in a dry tropical climate.
The Scots Bay formation was deposited in sie at least, in a
lake, because fish remains occur in the strata. This lake came
into existence soon after the extrusion of the North Mountain
basal flows, as is indicated by the lack of erosion in the upper
amygdaloid.
The Five Islands volcanics are interpreted as representing a
phase of igneous activity slightly earlier than that in which the
North Mountain basalt flows were extruded. The volcanics may
have come from central vents as well as from fissure eruptions.
The North Mountain basalt must have come from fissure
eruptions, and spread out over a large portion of the Triassic
geosyncline, as is indicated by the widely separated areas at
North Mountain and at Grand Manan. The geographical extent
of any individual flow is impossible to determine, but it appears
that the earliest flow, or series of flows, was the thickest.
The physiographic conditions accompanying the formation
of the Five Islands volcanics and the North Mountain basalts
are poorly shown. The base of the North Mountain basalt is
exposed only on Grand Manan, and there it is greatly weathered.
No evidence of contemporaneous lakes over which the lava
flowed has been found.
THE LOMBARD OVERTHRUST AND RELATED
LOGICAL FEATURES
WINTHROP P. HAYNES
Harvard University’
CONTENTS
TOPOGRAPHIC AND STRUCTURAL FEATURES
Folds
Faults
The Lombard Overthrust
A Normal Fault
STRATIGRAPHIC GEOLOGY
Pre-Cambrian
Spokane Formation
Empire Shale
Paleozoic
Cambrian
Absence of Ordovician and Silurian Strata
Devonian
Jefferson Limestone
Three Forks Formation
Carboniferous
Madison Limestone
Quadrant Formation
Mesozoic
Tertiary
Pleistocene
IcNEous Rocks
Granite
Diorite
Diabase
SUMMARY
TOPOGRAPHIC AND STRUCTURAL FEATURES
GEO-
The region involved in this discussion lies near the head of the
Missouri River in Montana. The chief topographic features are
hilly dependencies of the Little Belt Mountains.
2690
270 WINTHROP P. HAYNES
=
=
“Das da Formato
>
z
z
3
=
=
AER te
Fide hou Rormcioe
eS
| etic 7
a |
Beit Fremetion
HGNEOUS ROCKS
di +
of insler
wen ng
val 2eofert
+
ntowe Inter
Fic. 1.—Geological map of the region about Three Forks, Montana
THE LOMBARD OVERTHRUST AND RELATED FEATURES 271
The principal structural features are shown on the map (Fig. 1)
and in the structure sections (Fig. 2). The dynamic features
consist of folds and faults.
FOLDS
There is no indication that any marked deformation took place
in this region during the Paleozoic and Mesozoic eras. At the
close of the Cretaceous period, probably, the great series of sedi-
ments which had been accumulating began to be deformed. In
this region they were compressed into a series of closed folds with
a general northeast-southwest trend. These folds are usually
overturned to the southeast and pitch to the southwest. Two of
these folds were named by Dr. Pealet the Horsehoe anticline and
the Cottonwood isocline, both situated north of Logan, Montana.
East of Lombard, in the vicinity of Crane Station, there is a
northward-pitching anticline. In the long ridge west of the Mis-
souri River there is an elongate domal structure (Fig. 3) the
western side of which is interrupted by a normal fault and obscured
by an extensive overthrust. The southern part of this elongate
dome is overturned to the east and pitches steeply to the south
(Fig. 1; Fig. 2, section D-D; and Fig. 4).
FAULTS
The Lombard overthrust—The most important feature of the
structural geology of the region is an extensive overthrust fault
which has its southern end in the ridge north of Three Forks, and
extends a distance of at least 13 miles along the ridge to the north-
ern border of the map. The writer proposes the name ‘‘ Lombard
-overthrust” for this feature, because it is well exposed in the
canyon of the Missouri River near Lombard. Here the fault plane
dips about 40° to the west. This fault has brought strata of the
Belt Series over strata of Cretaceous age in the north, near Lom-
bard, and has brought the upper member of the Cambrian into
contact with the Carboniferous Madison limestone in the southern
end of the ridge (Figs. 2 and 5). The maximum displacement on
the fault plane near Lombard cannot be very closely estimated,
t A.C. Peale, Bull. U.S. Geol. Survey, No. 110, 1893.
WINTHROP P. HAYNES
N
Nn
SUOTJDIS [BOISO[OIH—'z ‘OI
AO ee STINET SO
ee e el ee
3 GOS Sham
cN
LP
ROKK EEE
Si 4
ats ; NS ae EEE
a
Higgs :
oS ps
ee eS er * ROK
SONG
Sire 1
mm lNee oats
ee
{egeNa
- ikea ah au eu |
YS ais! We -
Zy~ (St
THE LOMBARD OVERTHRUST AND RELATED FEATURES 273
but it is approximately two miles, and strata which are strati-
graphically about 6,800 feet apart are here in contact.
The age of the Lombard overthrust cannot be definitely deter-
mined, but it is certainly younger than the Cretaceous strata ex-
posed near Lombard, and probably older than the Lower Oligocene
deposits which occur near the southern end of the ridge and are
apparently undisturbed. It may therefore be assigned with some
uncertainty to very late Cretaceous or early Tertiary time.
A normal fault.—The only normal fault observed in this region
appears in the highest part of the ridge north of Three Forks and
west of the Missouri River. ‘This fault cuts across the western limb
of the elongate dome already noted, and has caused a repetition
of the upper part of the Gallatin formation and the base of the
Jefferson limestone (see Fig. 2, section C-C). This fault has a
length of about two miles and a diminishing throw to the south.
It could not be traced to its intersection with the overthrust fault,
but the displacement apparently dies out in that direction also.
The age of the normal faulting is considered to be the same as
that seen farther south in the Three Forks quadrangle, which is
dated as probably Pliocene.
STRATIGRAPHIC GEOLOGY
PRE-CAMBRIAN
The oldest rocks exposed in this region are a series of somewhat
altered sediments which occur below the base of the Cambrian,
and are considered to be part of the Belt Series, which are typically
exposed in the Little Belt Mountain region to the north and north-
east. The exposures of the Belt formation occur along the Gallatin
River east and northeast of Logan, and also north of Three Forks,
in a widening strip which trends northeastward and crosses the
Missouri River at the double horseshoe bend west of Lombard
(Fig. 1).
The exposures north of the Gallatin River are of rather coarse
micaceous sandstones and shales with thinly bedded siliceous lime-
stones. They are not divisible on the basis of lithological char-
acters into the various formations which characterize the Belt
Series at the type localities.
274 WINTHROP P. HAYNES
The extensive exposure of the Belt Series north of Three Forks,
which, so far as the writer was able to ascertain, has not been
described before, consists of two fairly distinct formations which
are considered to be equivalent to the Spokane and Empire forma-
tions of the Belt Series.
Spokane formation.—In the vicinity of the double horseshoe
bend of the Missouri River there is a fine section through the
Fic. 3.—Domal structure in ridge west of the Missouri River
Spokane formation. The formation at this place consists of a thick
series of well-stratified red and green slates with frequent layers of
ripple-marked and mud-cracked sandstone. The finer beds are
mostly very hard and siliceous and may be called argillites or even
metargillites. At several places in the section distinct folds are
visible, and also some faults. The minimum thickness of the
formation in this section is 1,650 feet, but the average thickness
is probably considerably greater than these figures.
Empire shale-—This formation, which overlies the Spokane
formation, 1s exposed in a long strip west of the Missouri River,
THE LOMBARD OVERTHRUST AND RELATED FEATURES 275
extending from near the southern border of the Fort Logan Quad-
rangle near latitude 46° to the double horseshoe bend. It consists
of evenly bedded, pale greenish shales with a few bands of quartz-
ite. The quartzite occurs in beds from 1 to 25 feet thick. The
formation is in apparent conformity with the overlying Cambrian
Fic. 4.—Folded Madison limestone near southern end of ridge, north of Three
Forks.
quartzite near the southern end of the exposure, but inasmuch as
the contact was traced for only a short distance an unconformity
with very slight angular discordance may have been overlooked.
Although the complete section of the Empire shale was not seen,
it is probable that 800 feet is a conservative estimate for the thick-
ness of the formation in this area.
276 WINTHROP P. HAYNES
There is still much disagreement among the various geologists
who have worked in the parts of the Cordillera where the Belt
Series is exposed, in regard to the age of the series and the corre-
lation of the different formations in it. The writer is disposed to
agree with the correlation in a recent report on the Philipsburg
quadrangle in Montana," in which strong evidence is shown for
a rather long erosion period between the Belt Series and the over-
lying Cambrian quartzite. The two formations identified by the
writer as the Empire and Spokane formations are therefore con-
sidered to be of Pre-Cambrian, Algonkian, or Proterozoic age.
PALEOZOIC
The Paleozoic formations recognized by the writer in this region
are for the most part continuous with those described by Dr.
Peale in his report on the “Paleozoic Section in the Vicinity of
Three Forks, Montana,’” and later in the Three Forks Atlas Folio.
His descriptions of the formations are very good and apply equally
well to the exposures In the region to the north, on the Fort Logan
Sheet. There are some additional facts concerning the thicknesses
and ages of the formations and a few changes in the nomenclature
which will be discussed under the following headings:
Cambrian.—A comparison of sections made by different geolo-
gists in the neighboring quadrangles shows that the seven lithologic
divisions noted by Dr. Peale in the Three Forks quadrangle are
persistent throughout southwestern Montana and the neighboring
part of Wyoming. It seems advisable to have but one name for
each of these divisions, and since locality names are preferable to
descriptive names the writer suggests that the nomenclature used
by Dr. Weed‘ in the Little Belt Mountains Folio be adopted for the
Cambrian throughout the whole region where these seven lithologic
divisions are recognized.
For purposes of mapping it seems best to keep the broader
divisions used by Dr. Peale, the two lower members forming the
Flathead formation and the upper five the Gallatin formation.
t Prof. Paper 78. U.S. Geol. Survey. 2 Bull. U.S. Geol. Survey, No. 110.
3 Atlas Folio, U. S. Geol. Survey, No. 24.
4 Atlas Folio, ibid., No. 56.
THE LOMBARD OVERTHRUST AND RELATED FEATURES 277
Ko
Be
JSNIYJAIOAO pIVGwO'T IY} JO UOIQDes IVRUTWTLIBeIGa— S$ “O1T
Be
278 WINTHROP P. HAYNES
The following section of the Cambrian northeast of Logan,
Montana, was measured by the writer.
Dr. Peaie’s Nomenclature Dr. Weed’s Nomenclature Thickness
1. Pebbly limestone = Yogo limestone 75 feet
2. Dry Creek shale = Dry Creek shale 20
3. Mottled limestone = _ Pilgrim limestone 300
4. Obolella shale = Park shale 280
5. Trilobite limestone = Meagher limestone 175
6. Flathead shale = Wolsey shale 450+
7. Flathead quartzite = Flathead quartzite 200
Total 1,500+ feet
Fossils from the Yogo limestone have been submitted by the
writer to Dr. Walcott, who considers them of Upper Cambrian
age, while those from the Meagher limestone are regarded by him
as of Middle Cambrian age. Apparently Lower Cambrian strata
are entirely absent in sections in this region. Although the bound-
ary between the Middle and Upper Cambrian strata has not been
definitely ascertained, it is likely that it comes between members
2 and 3.
Absence of Ordovician and Silurian strata.—In all of the sections
studied by the writer in the Three Forks quadrangle and the
neighboring district to the north, the Jefferson limestone lies in
apparent conformity on the Yogo limestone without any inter-
vening formations. The lower portion of the Jefferson limestone
has been considered by Dr. Peale and others as probably of Ordo-
vician and Silurian ages, although no fossils of those periods have
been found in it. Dr. Kindle’ has described the Jefferson lime-
stone and its fauna and established its age as chiefly Middle Devo-
nian with the lower part probably Lower Devonian.
In one or two good sections studied by the writer some rather
poorly preserved corals were found within 25 feet of the base of the
formation. These were identified as Favosites cf. limttaris Rom.,
which is rather common in much of the Jefferson limestone. The
presence of these fossil corals is regarded as indicating the Devonian
age of all of the Jefferson limestone, and since the gray Yogo lime-
tE. M. Kindle, Bull. Amer. Pal. No. 20, 1908.
THE LOMBARD OVERTHRUST AND RELATED FEATURES 279
stone immediately below the brown Jefferson dolomitic limestone
contains Upper Cambrian fossils, the writer believes that at this
contact there is a disconformity involving a hiatus in the sedi-
mentary record of this region from the close of the Upper Cambrian
to Lower Devonian time.
Further evidence in favor of this disconformity and strati-
graphic overlap is brought out by the presence in sections in neigh-
Fic. 6.—Cliff of Jefferson limestone north of Crane Station
boring regions to the west and southwest of intervening strata of .
different lithologic character between the Yogo limestone and the
Jefferson limestone, which in some cases contain fossils of Ordo-
vician and Silurian ages. One very complete section from the
Randolph quadrangle’ in northeastern Utah, with 3,000 feet of
Ordovician and Silurian strata between the Upper Cambrian lime-
stone and the Jefferson limestone, shows very clearly the hiatus
in the sections in the Three Forks quadrangle and the neighboring
region to the north and northeast.
«G. B. Richardson, Amer. Jour. Sci., XXXVI (1913), 406-416.
280 WINTHROP P. HAYNES
Devonian.—The strata of Devonian age in this region are
divided into two distinct formations, the Jefferson limestone and
the Three Forks formation.
Jefferson limestone: The Jefferson limestone is well described
by Dr. Peale’ as a massively bedded brown to dark-gray or black
crystalline magnesian limestone with the composition of a dolomite.
It is well exposed in the region under discussion in the form of
brown cliffs too to 200 feet high (Fig. 6). In a few of the ridges
Fic. 7.—Valley in Three Forks formation, near Rekap Station
north of Three Forks the limestone is black in color, but shades of
brown are the customary colors. In this region the Jefferson
limestone has a thickness of about 500 feet, but it diminishes in
thickness to the north and northeast, ,as noted in the sections in
adjacent quadrangles.
Three Forks formation: Lying upon the Jefferson limestone
is a series of shales and limestones which have been described by
Dr. Peale? and named the Three Forks shales. The writer has
made a careful study of this formation in all of this region, and has
measured numerous sections and made extensive collections of
A.C. Peale, Bull. U.S. Geol. Survey, No. 110, 1893, pp. 27-28.
2 [bid., pp. 29-30.
THE LOMBARD OVERTHRUST AND RELATED FEATURES 281
fossils from certain of the members. A detailed account of the
formation and a description of some of the fauna is in process of
publication elsewhere,’ so that only the more important points
will be mentioned here.
In all of the region included in Fig. 1 the Three Forks formation
shows seven fairly distinct lithologic divisions. These members
are well shown in the following section of the formation made
northeast of Logan near the Gallatin River.
Base of Gray Madison Limestone
1. Yellow arenaceous limestone............. 30 feet
2. Pale-yellow arenaceous shale............ 30
Bar lunplemissilershalernss amc uve wo. 8 0.5
4. Dark bluish-gray nodular limestone....... 9.5
Eemrssileyoreemsialeny. sau etes..c0 iia. 4 hae Os 47
(Yellow crystalline limestone............ 15
oe \ Gray MINES TOME He Peete Acca ean Tushar 12
7. Yellow and orange shales............... 78
Top of the Jefferson limestone. Total...... 222 feet
Another section farther north along the Missouri River at
Rekap Station (Fig. 7), shows the variation in thickness of the
different members.
1 and 2. Yellow sandy limestone and shale . 74 feet
Bepplackncoalivgshal emia arise caine elec ars 6
Ae Nodwlanerayalimestone yo) 0.0 2 rt 7
5. Fissile green shale |
SEH GVGL, Sepsis ula wl” A oeea ea goers Ae mee 120
6. Gray and yellow limestone
7. Pebbly yellow and reddish limestones and
ESN AVE WUSIS) 5a hae) Gay cee 80
SUroy eral heer Ae en een nn EL a 287 feet
It will be noted from these two sections that the members con-
sist of limestones as well as shales, so that the term “Three Forks
formation” is preferable to Dr. Peale’s name “‘ Three Forks shales.”’
In the region north of Three Forks and west of the Missouri
River there are numerous good exposures of the Three Forks
t Annals Carnegie Museum, Pittsburgh.
282 WINTHROP P. HAYNES
formation, whose erosion has formed some rather prominent valleys,
as shown on the map and in Figs. 7,8,andg. These valleys extend
in a general north-south direction and are nearly parallel with one
another. This repetition of the formation is due partly to folding
and partly to faulting.
The easternmost valley eroded in the Three Forks formation is
very narrow and shallow and extends northward along the eastern
Fic. 8.—Great valley in Three Forks formation. Ridge north of Three Forks
slope of the range of hills for five or six miles. The exposures are
poor because the strata are vertical or overturned and much crushed
by close folding.
This valley, at its southern end, swings around to the west and
opens into a much larger valley, which extends to the north for about
two miles. The structure which is the cause of this curious arrange-
ment of the valley is that of a southward-pitching anticlinal fold
which is overturned to the east. The strata in this very large
valley are in the western limb of the anticline (Figs. 8 and 9).
THE LOMBARD OVERTHRUST AND RELATED FEATURES 283
West of the. overthrust fault there is another valley formed in
the Three Forks formation. Numerous good sections of the forma-
tion were obtained in the small tributary gullies which cut across’
the dip of the strata on the western sides of these valleys.
The fossiliferous members of the formation are Nos. 1, 2, 4,
and 5. The general conclusions from a study of the fauna are that
the formation is very late Devonian in age, as reported by Dr.
Fic. 9.—View north from southern end of valley, at apex of southward pitching
anticline.
Raymond in 1907,’ and probably represents a transition into the
Mississippian in its upper part in members 1 and 2.
Carboniferous.—Throughout the mountainous part of south-
western Montana the Carboniferous formations are very prominent
and form conspicuous and precipitous cliffs. In the region about
Three Forks the Carboniferous strata attain a thickness of from
1,500 to 2,000 feet.
tP. E. Raymond, Amer. Jour. Sci., XXIII (1907).
284 WINTHROP P. HAYNES
Madison limestone: The lower formation has been named by
Dr. Peale’ the Madison formation and was subdivided by him into
three members; (1) the Laminated limestones at the base; (2)
Massive limestone in the middle, and (3) Jaspery limestone at the
top. The thickness of the Madison formation near Logan is about
1,300 feet. Although it forms conspicuous gray cliffs along the
ridge west of the Missouri River, its best exposures ate seen where
Fic. 10.—Missouri River in canyon in Madison limestone
the river has cut a deep canyon through it near Lombard, and also
in the smaller canyon along Sixteenmile Creek, east of Lombard
(Figs. ro and 11). -
A large collection of fossils was made by the writer from the
Madison formation in all parts of the region. ‘These fossils all
pointed to the general Lower Mississippian age of the Madison
limestone.
Quadrant formation: Lying in apparent conformity upon the
Madison limestone in this region is the Quadrant formation which
TAe CuLeale vOpNGl-433¢
THE LOMBARD OVERTHRUST AND RELATED FEATURES 285
forms the upper part of the Carboniferous system. The Quadrant
formation consists of two members, as noted by Dr. Peale.t
The lower is a red arenaceous limestone overlain by bands of
shale and limestone. The upper member is thinly bedded cherty
limestones alternating with quartzite layers. The top of the
formation is somewhat arbitrarily placed by Dr. Peale at the
base of a very massive and persistent quartzite layer which: is
Fic. 11.—Double horseshoe canyon of the Missouri River. View east showing
Lombard Station, and mouth of Sixteenmile Creek canyon.
considered to be the basal member of the overlying Ellis formation
of Mesozoic age.
The writer obtained a thickness of about 400 feet for the Quad-
rant north of Logan and 674 feet near Lombard. The exposure
of the Quadrant formation in the canyon near Lombard is excellent,
and a section was measured straight up the side of the canyon from
the top of the massive cliff of the gray Madison limestone to the
TAS ©. Reale, opi icit., p. 30:
286 WINTHROP P. HAYNES
top of the massive quartzite layer which forms the rim of the
canyon. The strata here strike N. 40° E. and dip 30° west (Fig. rr).
Massive pink and yellow quartzite (base of Ellis formation ?)....... 16 feet
Quartzite and arenaceous limestone in alternating layers........... 60
Massive white quartzite, limonite stains.................... Jon ee
Limestone .brécelan ie 2. 7 ee ae aA ce ee ee ee 2
Brown: arenaceous limestones. +) seer ee ee eee 62
Grayish-brown arenaceous limestone and talus................... 62
Pink ‘arenaceous limestone anyelitie ee eye ee ee ee 36
Yellowish-red arenaceous dimestonecee tee es a ee 47
Gray limestoneuni clifis /shalyyamibase pears eae. it ee eae 10
Reddish'shale:, 2 :oia Ge. Bee ee eee ioe a ans 5 ee 30
Greenish shale 22:4. 2.597) oyn 6 ee Pee os Se ee en ae 57
Bufi. shaly-limestoneand talus) eee eee ee ee ee 100
Gray bituminous limestone in cliff, with black shale layers......... 45
Compact gray and yellowish-brown limestone.................... 2
Black coaly shale with calcareous bands and gypsum veins......... 20
Brown-crystalline limestoneswaa nee ea eet es ee 4
Coaly ‘black ‘shales very tossiliferousicmrcme ome tee ante ce ee 50
Yellow arenaceous limestone in cliff, some quartzite bands......... 46
Red. shaly lmestomess" ter ae goer oe ee noe eI ete ee 10
Potak sere se et ee ee Sete une ER SAY RU SEER 674 feet
The fossils collected from the Quadrant formation indicate
that it is probably of Lower Pennsylvanian (Pottsville) age. The
absence of any strata referable to the Tennesseic suggests the
presence of a disconformity between the Madison and Quadrant
formations, although no other evidence of such a hiatus was
observed by the writer.
MESOZOIC
Mesozoic formations are rather poorly exposed in this region
and were not studied in detail by the writer. They consist of
shaly limestones and sandstones which are generally much less
resistant than the Paleozoic limestones and therefore usually
occupy lowland areas. These Mesozoic strata border the Missouri
Valley on both sides, and the more resistant layers form low ridges
which are parallel with the trend of the higher Paleozoic hills.
THE LOMBARD OVERTHRUST AND RELATED FEATURES 287
In this region the Ellis formation, consisting of sandy shales
and limestones with numerous layers filled with pelecypod shells,
lies on the Quadrant formation with no observed discordance of
dip. In the region to the south there is a well-marked reddish
sandstone formation of probable Triassic age intervening between
the fossiliferous Ellis and the Quadrant. Since the Ellis fossils are
considered to be Jurassic in age, it seems clear that there is a dis-
conformity in this part of the sections of this region.
Above the Ellis formation is a series of sandstones and con-
glomerates which have been called the Dakota sandstone by Dr.
Peale, but they have recently been shown to be more probably the
equivalent of the Kootenai formation of the region to the north.
These sandstones are therefore of probable Lower Cretaceous age.
Strata of Montana and Colorado age were identified by Dr. Peale
in the hills north of Logan, but there is now some doubt as to
whether they can be referred to a horizon as high as that.
TERTIARY
All of the Mesozoic and Paleozoic strata were involved in the
extensive orogenic movements which began at the close of the
Cretaceous in this region.
The type of folding and the associated overthrust faulting has
already been described in this paper. Extensive erosion reduced
the region to comparatively low relief in Tertiary times. . The
great lowland areas were filled in by sedimentary deposits of sand-
stone, limestone, and volcanic ash to a great depth. The major
features of the present drainage were established on this late Ter-
tiary surface and gradually, through uplift and erosion, they were
brought into discordance with the underlying structure, as is well
shown by the double horseshoe canyon of the Missouri River west
of Lombard.
This whole series of Tertiary valley sediments has been grouped
under the heading of the Bozeman formation for convenience in
mapping. Dr. Peale’s name ‘‘Bozeman Lake Beds” seems no
TW. R. Calvert, Bull. U.S. Geol. Survey. No. 471—-E, 1912, p. 53-
288 WINTHROP P. HAYNES
longer applicable, since they have been shown to be due to sub-
aerial and fluviatile deposition rather than to lakes."
The Bozeman formation here is chiefly of Miocene age, but in
some parts of the region strata of Oligocene (White River) age have
been identified.
PLEISTOCENE
The hills in this region were evidently too low for local glaciation
and no signs of regional glaciation have been observed as far south
as this in Montana. Gravel terraces. along the rivers indicate
greatly increased stream action in Pleistocene times.
IGNEOUS ROCKS
The igneous rocks in the region north of Three Forks are rela-
tively unimportant, and are in the form of rather small intrusions
of three different rock types.
GRANITE
About two miles west of Lombard, in the double horseshoe bend,
the Missouri River flows for a short distance through a gorge cut in
an intrusive mass of granite. Only the eastern boundary of this
granite could be accurately mapped, but the approximate western
limits are noted on the map.
The granite:is of a light-gray color, with a medium fine texture
and a somewhat porphyritic structure. The minerals recognized
in a megascopic examination are white and grayish feldspar some-
what kaolinized, quartz in small amounts, and hornblendes mostly
altered to chlorite. Under the microscope the feldspars are seen
to be deeply kaolinized, but are chiefly orthoclase with some albite.
There is a considerable amount of hornblende which is altered in
part to chlorite and epidote. Some biotite and magnetite are also
present.
In places this rock is almost entirely without quartz and there-
fore grades into a syenite. It seems to correspond closely with the
description of the syenite of Yogo Peak’ and vicinity in the Little
Belt Mountains, which is noted as grading into a granite-syenite-
tH. F. Osborne, Bull. U.S. Geol. Survey, No. 361, 1909, p. 28.
2 Atlas Folio, U.S. Geol. Survey No. 56, 1890.
THE LOMBARD OVERTHRUST AND RELATED FEATURES 289
porphyry. The granite has a well-developed set of joints which
strike northeast and dip 80° east, and are about parallel with the
contact with the Belt Series.
The age of the granite cannot be definitely determined at this
place, but it is probably about the same age as the granitic and
syenitic intrusions of the Little Belt Mountains, which are post-
Cretaceous and probably early Tertiary in age.
DIORITE
Small irregular intrusive masses of diorite and diorite porphyry
occur in the vicinity of Dunbar’s mine, north of Three Forks.
These intrusions cut the white Tertiary limestones which at this
locality are considered to be of Lower Oligocene age. The diorite
was observed to have nearly vertical contacts with the limestone
and to occupy a much smaller area than is indicated on the geologic
map of the quadrangle. The diorite porphyry seems to be a local
variation in the normal diorite and its distribution can be shown
only on a detailed map of the district.
Specimens of fresh diorite were obtained from the dump at
Dunbar’s mine. The rock from the main shaft is of medium fine
texture and evenly crystalline. It consists of an even mixture of
black hornblende and gray feldspar. Under the microscope the
rock is seen to consist of greenish-brown to dark-green pleochroic
hornblende and labradorite feldspar. Apatite, olivine, and mag-
netite occur in small amounts as accessory minerals. Specimens
of diorite from a shaft about a half-mile to the south show a small
amount of pale-pink orthoclase feldspar scattered through the
rock.
Some of the diorite from a small intrusion which cuts the
Cambrian formations a few miles north of the mine is distinctly
porphyritic and consists of hornblende phenocrysts in rather
slender crystals about a half-inch long in a gray ground-mass of
plagioclase feldspar and hornblende. Magnetite and apatite occur
in small amounts scattered through the ground-mass and are
visible under the microscope. The rock is deeply weathered at the
surface and the hornblende is mostly altered to chlorite, and the
feldspar is kaolinized.
290 WINTHROP P. HAYNES
There are zones of altered rock along the contacts of the diorite
and the Tertiary limestone which are well exposed about Dunbar’s
mine. In this contact zone are many secondary minerals which
include garnets, and several copper-bearing minerals, chiefly
chrysocolla, with some malachite and azurite. It is the presence
of these minerals which has caused the development of Dunbar’s
mine. This mine was not in operation during the summers of 1912
and 1913 when the writer visited the region.
DIABASE
A rather large intrusion of diabase was observed by the writer
in the extreme northern part of the region, about a mile west of
Lombard. This somewhat irregular dikelike intrusion follows
the plane of the thrust fault across the double horseshoe bend of
the Missouri River and varies in width from roo to 500 feet. The
intrusion has produced a noticeable contact effect on the country
rocks, particularly on the Cretaceous rocks on the east side, which
are indurated near the contact.
The diabase is deeply weathered near the surface and has a
rusty brown color. It forms a very conspicuous massive wall on
the north side of the Missouri canyon, northwest of Lombard. The
rock shows the ophitic structure well and is composed of augite
and labradorite with some olivine, magnetite, and apatite. The
age of this intrusion cannot be very definitely placed but it is clearly
post-overthrusting, and therefore of Tertiary age.
SUMMARY
The contributions of this article may be summarized as follows:
rt. A new geologic map of a portion of the Fort Logan region,
and a revised geologic map of a part of the Three Forks region.
2. The recognition of an extensive overthrust in the north-
western part of the region, ‘‘the Lombard overthrust.”’
3. New facts relative to the stratigraphy of the region mapped,
including the identification of a portion of the Belt Series, and the
recognition of a disconformity between the Yogo limestone and the
Jefferson limestone.
4. Detailed sections of some of the Paleozoic formations.
5. The igneous rocks and their manner of occurrence.
THE SKELETON OF TRIMERORHACHIS
S. W. WILLISTON
University of Chicago
A year ago, in a paper on the structure and habits of Tri-
merorhachis, I said, that “‘it will only be by the fortunate discovery
of a connected skeleton that the tail, ribs, and feet will be made
known.’* Such a specimen has been discovered and _ skilfully
worked out by Mr. Paul Miller, a photograph of which, as pre-
pared, is shown in Fig. 1. The specimen came from the pale-
ontologically famous Craddock Ranch, near the town of Seymour,
Texas, from the same horizon as that of the skeleton of Seymourza,
described by me a few years ago, and within a stone’s throw of its
locality. Its horizon seems to be nearly the same as that of the
Craddock bone-bed, from which so many remarkable specimens
have come. When found, the specimen was inclosed in a large,
irregular nodule of bright red claystone; nothing was visible of
it except the extreme tip of the nose and the base of the tail, as
shown by a fracture. The under side of the nodule was smoothly
convex both longitudinally and transversely; its upper side was
irregular and gnarly. With this specimen, and in immediate rela-
tion with it as it lay upon the surface, were found a number of
pieces, which, when fitted together, formed a block about one foot
in length, which seemed to be a continuation of the tail end of the
larger block. When fully prepared, however, the smaller block
proved to belong to a second specimen of Trimerorhachis, includ-
ing about twenty chiefly precaudal vertebrae, with their ribs and
an imperfect femur.
The larger specimen, that figured herewith, is a nearly complete
skeleton as far back as the sixth or seventh caudal vertebra. The
1 Cope, Proc. Amer. Phil. Soc., XVII (1878), 524; XIX (1880), 54; Amer. Nat-
uralist, XVIII (1884), 32; Case, Revision of Amphibia and Pisces of North America
(1911), 39, 106; Huene, Bull. Amer. Mus. Nat. Hist., XXXII (1913), 372; Broom,
Anatom. Anzeiger, XLV (1913), 73; Bulletin Amer. Museum, XLV (1913); Williston,
Journal of Geology, XXI (1913), 625; XXII (1914), 160; XXIII (1915), 246.
291
S. W. WILLISTON
bones, as usual in such nodules, are white and rather soft, rendering
Fic. 1.—Trimerorhachis.
in original matrix.
Specimen No. 1271,
About one-fourth natural size.
their preparation in the
hard matrix difficult. It
has been worked out so
far as was possible
without going below the
surface of the bones.
The
come to rest in a prone
cadaver had
position, apparently,
with the head and tail
directed obliquely up-
ward, its vertebrae con-
nected throughout in a
sinuous curve, and the
ribs nearly all in im-
mediate connection
with their articulating
The right
humerus had been dis-
diapophyses.
located, and lay near
the posterior end of the
right mandible, with its
radius a little distance
The
right femur lay nearly
from its distal end.
in apposition with the
acetabular part of the
ium; its distal part
had been eroded away.
Doubtless both the front
and the hind legs of the
left side are buried some-
where in the matrix.
The
wholly unexpected fact
remarkable and
disclosed by these speci-
THE SKELETON OF TRIMERORHACHIS 293
mens is the presence of a thin bony skin or armor closely
sheathing the whole body, with the exception of the skull and
clavicular girdle. As the cadaver came to rest it was immersed
in the soft mud to near its middle. The skin lining the cavity thus
made retains its original position. On the decay of the body, the
bones fell to the lower part, closely covered everywhere by the skin
of the upper part of the body. On the right side the skin had
bulged outward near the middle. When first uncovered the bones
were concealed everywhere by the skin. It has been removed on
one side or the other to expose the bones, and between them, in a
few places, to show the skin of the under side of the body, which
in some places lies in juxtaposition with that of the upper side,
in others séparated by a thin layer of the matrix.
A dermal covering of peculiar type in Trimerorhachis has been
several times observed by Cope, Case, and myself, but it was
assumed that it covered the ventral region only, and its nature
was ill understood. The present specimens show very conspicu-
ously that it covered the whole body, with the exceptions men-
tioned; in the preparation of the skull not a trace of it was seen,
but it is closely connected with its hind margins. In no place in
these specimens does it appear to have been more than a milli-
meter in thickness. It is composed of slender and delicate bony
fibrillae, in short pieces, and apparently in several layers. In
another specimen (Fig. 3, B, C,) transverse sections show that the
bony rods were in numerous layers. As these fibrillae lie in this
specimen they extend through a thickness of 6 or 8 mm., and are
separated from each other by intervals greater than their own thick-
ness. It seems hardly possible that postmortem causes could have
separated them so uniformly, and one must conclude that they were
imbedded ina considerable thickness of integument, at least a fourth
ofaninch. How long any of the rods were I cannot say; the longest
connected piece that I trace is scarcely a fourth of an inch. It is
still possible that the sections represent the ventral skin, since
nothing of their character is visible in the connected skeleton.
Notwithstanding this thickness, the skin must have been
flexible to have followed every inequality of the bones below it.
It was doubtless covered by a smooth epidermis.
204 S. W. WILLISTON
Thirty-one precaudal
vertebrae are visible, all
in close articulation, the
first one apparently with
the condyle. That the
vertebral column was
very flexible is evident
from its sinuosity as it
lies in the matrix, with-
out break. The general
structure of the verte-
brae is well known from
isolated specimens.
The pleurocentra are
very small, and the
intercentra are more or
less U-shaped, indicating
a large amount of carti-
lage. The spines are of
nearly uniform height
throughout the column,
curving backward and
upward, and slightly
dilated at their extrem-
ities. Their het@he
above the plane of the
zy gapophyses is nowhere
more than 14 mm.; their
width at the ends from
8 to 10 mm.
The ribs are preserved
very completely in posi-
tion; all have been ex-
posed on one side or
the other except two,
Fic. 2.—Trimerorhachis. Skeleton, from above, th ‘ddl Th
as restored from specimen shown in Fig. 1. One- ai - ven &. =
fourth natural size. first eight -arew te
THE SKELETON OF TRIMERORHACHIS 205
longest, measuring about 52 mm. They also have a considerable
curvature and are more or less expanded at their extremities.
With the tenth or eleventh they have decreased in length to 45 mm.,
are less curved, and not dilated at their distal ends. Thence to
the tenth precaudal they are of uniform length, more slender, and
pointed. When seen from above these are all slender and nearly
straight, with a moderately expanded proximal end; when turned
upon their sides they are broader, somewhat curved, and with
a more dilated head. Apparently some of them at least have a
capitular prolongation in articulation with the intercentra. The
first two precaudal ribs are slender, pointed, and entirely free,
and about one inch in length.
The right humerus lies near the angle of the right mandible,
as will be seen in the photograph, with its head directed forward,
and with the radius somewhat removed from its distal end. There
are no remains of the skin either above or below these bones.
Some half-dozen skulls of Trimerorhachis have now been obtained
with the peculiar clavicular girdle in position or nearly so, lying
more or less between the mandibles posteriorly. In the drawing
(Fig. 2) I have outlined in interrupted lines a clavicular girdle of
another skull of the same size as the present one, in position,
placing it farthest back of any of the connected specimens. The
angles of the clavicles with their ascending process must indicate
the position of the scapula and articulation of the humerus. The
scapula is hidden and not certainly determinable in this specimen,
though the edge of a protruding bone at the inner side of the distal
end of the humerus, as it lies in the matrix, is probably that of the
scapula. The scapula, ilium, and limbs of the left side are doubt-
less preserved in this specimen covered by the skin and matrix,
but it has not been thought wise to sacrifice so much of the speci-
men as might be necessary in the search for them. In all the
material from the bone-beds so far examined not a trace has been
found of hand or foot bones, so that nothing can be said of their
structure.
The right ilium lies in place in the matrix, in a vertical position
opposite the ends of the first two presacral ribs. The bone is
relatively very small, as will be seen from the figure. Among the
206 S. W. WILLISTON
numerous ilia in the collections (I have seen about two score)
there is no indication of roughening for attachment to sacral ribs.
So far as was prudent the matrix has been removed about the
ilium; there are no indications of ossified pubis or ischium. The
proximal end of the right femur lies nearly in place opposite the
Fic. 3—Trimerorhachis Integument. Properties of Matter, 1902, p. 181.
3 The chief conclusions reached by Mare are contained in the following brief
citations (Zeitschr. f. phys. Chem.):
“Tt was found that the rate of crystallization, so far as it could be determined,
of all the substances investigated was proportional to the square of the supersatura-
tion”’ (op. cit., LX VII [1909], 500).
a . that a very rapid change precedes the crystallization proper, which is
interpreted to be an adsorption phenomenon. Support is given to this view by the
THE LINEAR FORCE OF GROWING CRYSTALS BBY]
again, ““On Adsorption and Saturated Surfaces” (1913),’ without
developing any single fact in support of the hypothesis advanced
by Bruhns and Mecklenburg. |
Neither capillarity nor adsorption exerts any upward pressure
on the loaded disks of porcelain in the experiments under discus-
sion, while adsorption does not prevent the exercise of the very
great downward pressure due to the surface tension of water. Yet
the alum crystallized and the disks were raised.
In the opinion of the observers it was essential to the elevation
of the disks that evaporation should be complete.t Was the eleva-
tion, then, produced after the crystallization was complete and the
mass solidified? ‘The observers make no such statement, which,
indeed, would seem absurd. But if the raising was not effected
after solidification, it must have been produced before solidifica-
tion, or while the underlying film was liquid and while crystalliza-
tion was in progress, in opposition to capillary force as well as to
the weight of the disks and their load.
Liesegang appears to have appreciated this anomaly in Bruhns
and Mecklenburg’s statement, though accepting their conclusion,
for he sought to relieve it by the following explanation (referring
to the experiments of Bruhns and Mecklenburg): ‘‘ Nicht ein Wach-
stumsdruck der Krystalle sondern Capillar- und Adsorptionskraite
bewirkten hier also die Hebung. Das heisst die Leistung war schon
volbracht ehe Kristalle auftraten.”? ‘‘The lifting was done before
the crystals formed.” This is not claimed by Bruhns and Meck-
lenburg, nor supported by any experimental evidence which they
fact that this preliminary phenomenon is particularly sensitive to slight impurities
upon the crystal surface” (ibid., LX XIII [1910], 718).
“No relation could be established between concentration and the quantity of
adsorbed material” (ibid., LX XIII [1910], 686).
“Tn all cases the rate of crystallization is diminished by the addition of substances
which are adsorbed by the crystal, eventually even to the point of becoming practically
zero”’ (tbid., LX XIII [1910], 718).
“Tt was shown that the substances chiefly adsorbed by crystals are colloids, while
the crystalloids are adsorbed only very slightly” (zbid., LXXXI [1913], 692).
t Bruhns and Mecklenburg, op. cit., p. 106: “‘Es sei aber ausdriicklich betont
dass der Versuch nicht gelang, wenn wir nicht die Masse bis zum Grunde trocken
werden liessen.”’
2R. E. Liesegang, ‘“ Kristallisationskraft,’ Naturw. Rundschau der Chem. Zig.,
Zweite Jahrg. 1913, p. 183.
328 GEORGE F. BECKER AND ARTHUR L. DAY
offer, and indeed would seem to be without any foundation
whatsoever.
We fail to see any reason for connecting the rise of the porcelain
disks with capillarity or with adsorption. These could only
obstruct the elevation, and must have been overcome by a linear
force attending the crystallization of the alum, as in our own
experiments.
It is not expedient, however, to rely on reasoning alone in
matters of physics if experimentation is practicable, and we accord-
ingly made the effort to separate the forces to which Bruhns and
Mecklenburg appeal, through evaporation of solution of a colloid
(gum arabic) in which was immersed a block of glass replacing the
alum crystal between the two plates of glass (Table VII). Evap-
oration to dryness caused no rise of the upper glass plate as it
TABLE VII
BLock OF GLASS REPLACING THE ALUM CRYSTAL (Fic. 1). Loap (Grass PLATE) =
24 Gm. GLAss BLock AND LOAD COMPLETELY IMMERSED IN 2 PER CENT SOLU-
TION OF GuM ARABIC IN WATER. ROOM TEMPERATURE
Time (Hours) Sean ‘Thickness Notes
ORiii. eee eee | 37.2609 | o mm.
i fa pen aarti ic | 37.2649 +o.004
Donte ee WRe nee 37.2654 +0.0045
PA Est ie eRe ghey Pein 37.2621 -++o.001
[OCR aces ao Bis ecko | 37.2615 | +o.001 Evaporated to dryness
Refilled with 2 per cent gum arabic solution; all conditions unchanged
CO Be has Ce te | 37.2669 +o .006
ci ee eee | 37.2670 +0.006
WORT vo cisucntess ane | 37.2670 +o.006
TLORO weiss ace Or | 37.2653 +o.004 Evaporated to dryness
should have done were capillarity and adsorption the source of
energy. A saturated solution of alum added to the colloid
(Table VIII) starts crystal formation and growth at once, but at
a rate much slower than in the cases where no colloid was present.
This is in full accord with the experiments of Marc.t
In addition to confirming the results of Marc, Table VIII offers
independent and explicit experimental proof that the “linear force”’
appears here also in spite of the action of the colloid in retarding
t See footnote, p. 326.
THE LINEAR FORCE OF GROWING CRYSTALS 320
diffusion through increased viscosity and in interposing an adsorp-
tion film at the crystal surface.
Conditions in ore deposits appear to correspond very well with
those in the laboratory, for crystallization may be found accom-
panied by local evidence of linear thrust or not, according to the
magnitude and distribution of the opposing forces. Its failure is
most often manifest in comb structure, found: in crevices whose
walls are each lined with tightly adhering crystals which either
interlock and extend quite across the crevice or grow together near
the central plane and mutually exclude further development.
Such comb structure is common in veins, but far from universal.
TABLE VIII
SAME PLATES, BLOCK OF GLASS, AND CONDITIONS, EXCEPT
THAT THE 2 PER CENT Gum ARABIC SOLUTION HAs
BEEN SATURATED WITH POTASSIUM ALUMINIUM SUL-
PHATE
Time (Hours) Reine in Thickness
(Oh yee nei Nae ee 37.2653 ° mm.
AP OR aurea tae ee 37.2694 0.004
Das Ne cslgiat iad ipsa err ee 37.2721 0.007
QO} wetieepaiese ee aval caen: 37.2812 0.016
MOB eG ieine nets see meastyee 37.2818 0.017
TO ath eh a, deni yee ee 37.2842 0.019
OG ete ears vatiois eae es 37.2857 0.020
TAO agi ites eared enero tac 37.2873 0.022
DEG Ae eect er Cr eae 37.2916 0.026
Diamante a eek Anan ae 37-3079 0.043
DSi te a eee see RET cE Bo QUge) 0.053
3 OOPaae es nsec: Sensi BY] sf) 0.052
AOOii te corset ees as 37.3185 0.053
It may be inferred, further, that linear pressure plays a subordi-
nate part in much more complex occurrences.
Messrs. Bruhns and Mecklenburg seem to have misunderstood
the last paragraph of our paper in which we called attention to the
fact that the linear force of growing crystals cannot be disposed of
as a mystery comparable to the growth of plant roots. It is a
sharply defined physical process open to quantitative experimental
investigation. It may not be fully understood, but it is no mystery.
330 GEORGE F. BECKER AND ARTHUR L. DAY
. The conclusion of these authors seems to be that during growth,
material is added only to the upper and lateral faces of the crystal,
so that a molecule once added remains at its original level. This
was Kopp’s contention in opposition to Lavalle, whose conclusions,
however, were confirmed by Lehmann and others, including our-
selves. ‘This is in fact the root of the matter. Ifa given increment
of the mass after deposition remains at its original level throughout
the subsequent growth of the crystal, this exerts no linear force;
while if the motion of the particle has a vertical component in
consequence of the vertical extension of the lateral faces of the
crystal, linear force is exerted. .
On the other hand, if several crystals are immersed, one or more
of them being loaded while others are not loaded, the loaded crystals
grow only when the concentration of the solution in contact with
them exceeds the saturation concentration for each crystal. Pres-
sure, of course, increases solubility or raises the point of saturation
for most salts.‘ Hence in such circumstances the unloaded crystals,
or, more strictly, the less loaded crystals, usually are the only ones
to exert lifting power, but in this case, also, growth raises the weight
of each crystal.
Thus Bruhns and Mecklenburg’s results with loaded porcelain
disks are readily explicable. They experimented with solutions
containing many small crystals, some of them weighted, others free.
The disks did not rise measurably until the liquid was low and its
surface (and consequent rate of evaporation) greatly increased by
protruding solid matter, or until the crystals reached from the
bottom of the dish to the disks, after which the disks were
lifted.
Repetitions of this operation, extending over a few days, pro-
duced aggregate displacements of 5.o mm. If to this be added our
original measurement, twice confirmed in the course of the present
control tests, that this linear force, because of the narrow rim
« As is well known, if the solution of a solid at constant temperature is attended
by a diminution in total volume and a liberation of heat, pressure increases solubility.
Such is the case for most crystalline solids including the alums. If the change in
volume accompanying solutions is an increase, as in ammonium chloride, pressure
decreases solubility.
THE LINEAR FORCE OF GROWING CRYSTALS 331
through which it acts, actually exerts a pressure of the same
order of magnitude as the breaking load of the solid crystals, need
there be further hesitation in assuming that this is a force to be
reckoned with in engineering" or in geology ??
SUMMARY
In 1905 we showed by appropriate experimental evidence that
a single crystal immersed in its own saturated solution, and growing
by reason of the potential supersaturation of the solution resulting
from evaporation will lift a weight placed upon it. This observa-
tion has been confirmed in the present paper.
In 1913 Bruhns and Mecklenburg placed two crystals in a similar
saturated solution, one loaded and the other free, and noted that the
load upon the one crystal was not raised, although the free crystal
grew rapidly. From this experiment they were led to deny the
power of a crystal to lift a weight of foreign substance, although
admitting the power of the unloaded crystal to lift its own substance.
They appear to have overlooked in this conclusion the fact that the
solubility of the loaded crystal is for most substances greater than
that of an unloaded one, and also that this is a difference in degree
only, for the unloaded crystal also supports weight (its own).
In consequence of this greater solubility, with an unloaded and
a loaded crystal in the same solution, the necessary condition of
potential supersaturation will be reached in the liquid adjacent to
the unloaded crystal before it is reached in the other, and the
growth of the unloaded crystal thereafter may keep the concentra-
tion below that necessary for the growth of the loaded crystal.
This appears to be the condition reached in Bruhns and Mecklen-
burg’s experiment. If it happens, however, that the rate of growth
1Cf. the investigations of Dr. Hans Kiihle, ‘“Die Ursache des Treibens der
Zemente,” Tonindustrie Zig., XXXVI (1912), 1331-34; and of Klein and Phillips,
“Hydration of Portland Cement,” Technologic Papers of the Bureau of Standards
No. 43 (1914), pp. 50, 56, 57.
2Cf. the recent observations of Stephen Taber, Virginia Geol. Survey Bull.,
No. VII (1913), p. 222; also G. D. Harris, ‘Rock Salt, Its Origin, Geological Occur-
rences and Economic Importance in the State of Louisiana,” Geol. Survey of
Louisiana, Bulletin No.7 (1907), p- 75.
332 GEORGE F. BECKER AND ARTHUR L. DAY
of the unloaded crystal is insufficient to take up all of the excess
concentration provided by the continued evaporation, then super-
saturation will increase. It is entirely possible under these condi-
tions that the potential supersaturation necessary for the growth
of the loaded crystal may then be attained or even exceeded, and ©
that the loaded crystal will also grow and lift its load. This condi-
tion was attained experimentally without difficulty in the observa-
tions recorded in this paper. If concentration increases still more
rapidly, and exceeds the ability of both unloaded and loaded crystals
to take up, through their continued growth, all the matter in excess
of the saturation concentration, then additional nuclei may form
upon which excess matter may be deposited. This appears to have
been the condition attained in the last series of Bruhns and Meck-
lenburg’s observations in which the solution was evaporated to dry-
ness.
Here six disks of porcelain loaded with weights were all raised
a millimeter or more in the same solution, but Bruhns and Mecklen-
burg attribute this result to the action of capillarity and adsorp-
tion, and deny the competence of the “linear force of growing
crystals”’ to effect such mechanical displacements.
A simple analysis suffices to show that capillarity in a solution
evaporating to dryness can have no other effect than to press the
crystal down upon its base with a force equal to 27 V/d?, where T
is the surface tension, V the volume of the drop of liquid between
the crystal and its base, and d the distance separating the two, and
that the lifting action observed by Bruhns and Mecklenburg has
occurred in spite of this opposing force and not because of it.
Adsorption delays diffusion and diminishes the rate of growth, but
does nothing to promote it. These forces therefore cannot be
appealed to in explanation of the lifting observed by Bruhns and
Mecklenburg and by us.
We therefore return to the original thesis that the growth of
crystals in saturated solution develops a linear force in the direction
of the load, and that neither the magnitude of the load (up to the
breaking load) nor its character (whether exclusively crystal sub-
stance or partly foreign substance) has any other effect than to
THE LINEAR FORCE OF GROWING CRYSTALS 333
increase solubility and so to raise the concentration necessary for
potential supersaturation and growth upon the loaded crystals.
This degree of supersaturation is readily attainable through evapo-
ration or otherwise, and when attained the loads are lifted. With
this thesis established, there is no conflict between the observations
of Bruhns and Mecklenburg and our own, and all the experimental
evidence offered is perfectly correlated.
CARNEGIE INSTITUTION OF WASHINGTON
GEOPHYSICAL LABORATORY
February, 1916
THE CLASSIFICATION OF THE NIAGARAN FORMATIONS
OF WESTERN OHIO"
CHARLES S. PROSSER
Ohio State University
CONTENTS
INTRODUCTION
DESCRIPTION OF SECTIONS
Ludlow Creek Sections
Section of Ludlow Falls and the Smith Quarry
Section of Western Wall of the Smith Quarry
Section of the Otto Ehlers Quarry
Section of the Maxwell Quarry
General Section along Ludlow Creek
Correlation of the Brassfield Limestone
Other Sections of Western Ohio
Sections in and near Covington
Section of the Jackson Stone Co. Quarry
Section of the J. W. Ruhl Quarry at Covington
Section near Lewisburg
Section at the Lewisburg Stone Co. Quarry
Section near Laurel, Indiana
Derbyshire Falls Section
INTRODUCTION
There has been more or less uncertainty concerning the names
which ought to be used for the Niagaran formations of the Silurian
system in western Ohio together with their correlation with the
formations of the same series in eastern Indiana. Field work in the
summer of 1914 in this area has cleared up some of this uncertainty
and part of the results are deemed of sufficient importance to war-
rant their early publication.
t Presented at the Ohio Academy of Science meeting in Columbus on November 28,
1914, and at the American Association for the Advancement of Science meeting in
Columbus on December 28, 1915. Published by permission of the State Geologist
of Ohio.
334
THE NIAGARAN FORMATIONS OF WESTERN OHIO — 335
A series of sections at Piqua, along the Stillwater River between
Covington and West Milton, and along Ludlow Creek in Miami
County, and in the vicinity of Lewisburg, Eaton, and New Paris
in Preble County, has furnished the writer the complete section
from the Ordovician to the highest Silurian rocks of this area.
DESCRIPTION OF SECTIONS
The contact of the Ordovician and Silurian systems is clearly
shown at Ludlow Falls, and the succeeding rocks as high as they
extend in this region are admirably exposed at the falls and in the
series of quarries which border the creek for some distance above
the falls. Sections at other localities agree with the ones along this
creek and show that the general order of succession is essentially
the same for these counties.
LUDLOW CREEK SECTIONS
Four of the series of sections measured along Ludlow Creek will
be given, which were checked by several other sections along the
same stream. From these a general section of the rocks shown
along this creek can be compiled.
The following section is based on the outcrops in the north-
eastern corner of the Colonel Samuel B. Smith quarry and the bank
at the northern end of Ludlow Falls:
SECTION OF LUDLOW FALIS AND THE SMITH QUARRY
ToTaL
: THICKNESS TD SiSSESE
No. Feet Inches Feet Inches
6. Dayton limestone——Northeast corner of the
Colonel Samuel B. Smith quarry. The rock
varies from light gray to somewhat darker gray
on fresh fracture and some as weathered is
bluish-gray. Other layers on the weathered
faces are buff to brownish or rusty color from
disintegrated iron pyrite. The rock splits into
even-bedded layers; but the surfaces of the
bedding planes are frequently rather rough and
show stylolites structure. The majority of the
layers vary in thickness from 2 to ro inches,
most of them ranging from 4 to 6 inches. The
lowest layer is from 3 to 4 inches thick, and the
336 CHARLES S. PROSSER
THICKNESS eno
No. Feet Inches Feet Inches
next one above 10 inches, which in places splits
into 2 layers with hackletooth structure at con-
tact. The lower layers contain iron pyrite,
which stains them on weathering. There are
also calcite crystals, but no fossils were noted 8 2 AI 5
. Brassfield limestone.—Crystalline and crinoidal
light-gray to pinkish limestone, with very ir-
regular bedding planes. Specimens of corals
and Stromatopora are rather common, and
there is an occasional Brachiopod shell. In
places there are irregular masses of blue shale
which contain a good many corals. This is the
bottom of the quarry at this corner, and the
barometer with an interval of only 7 minutes
read the same at the highest outcrop of the
Brassfield limestone on the northern bank of
Ludlow Creek, just above the Dayton, Coving-
ton, and Piqua traction bridge and Ludlow
On
4. The upper 5 feet of the bank at the northern
end of Ludlow Falls varies in color from light
gray to pinkish and greenish, while some of it
when weathered is brownish. Most of it is
coarsely crystalline, part of it is very crinoidal,
and it contains large numbers of Bryozoa,
corals; and"Stromatopora, .4-- see ee oa: 5 ° 28 2
3. Rather massive, more or less crystalline, lime-
stone, which is of light-gray color, somewhat
brownish as weathered; and some of it is very
light gray, almost white, and is locally called a
“marble.” It contains very few fossils, if any.
At the center of the falls there are 11 feet of the
Brassfield limestone undercut by the water of
the Stream: 02 foc. aik ss a ee 16 6 23 2
2. Belfast bed*—Blue rock, which is probably
argillaceous and rather sandy, with layers from
2 to 6 inches thick and the average about 3
inches. This zone was thought by Dr. Foerste
t The writer understands Dr. Foerste to now refer the Belfast bed to the Rich-
mond, which is also the opinion of Dr. E. R. Cumings, based on a study of its
Bryozoa. Dr. W. H. Shideler, however, has found certain Brachiopods in the Bel-
fast which he thinks allies it with the Brassfield.
THE NIAGARAN FORMATIONS OF WESTERN OHIO — 337
: TOTAL
THICKNESS GRTIORNESS
No. Feet Inches Feet Inches
to represent the Belfast, since he wrote, “If
they [the layers] represent the Belfast bed of
more eastern sections, as is believed to be the
case, they certainly have changed considerably
from the typical form of the rock.”?......... 2 8 6 8
1. Richmond formation—Rather thin-bedded
blue rock to shaly layers, perhaps with sandy
to calcareous composition. This zone extends
to water level and blue shale is washed out of a
pit that has been dug still deeper by the water.
About 5 feet of this zone are shown in the bank
Peomechersouthermusider cry cet a2 ei) eye 4 ° 4 °
The foregoing section gives 26 feet 7 inches for the thickness of
the Brassfield limestone. This agrees fairly well with the estimate
based upon the thickness of the Brassfield on the northern bank
at the falls and the section in the Big Four Railway cut west of the
station on the southern side of the creek. Mr. W. Z. Miller, my
assistant, made the top of the Brassfield limestone in the railway
cut about 7 feet higher than the top of the ledge on the northern
bank of the creek, which gave 284 feet for the total thickness of the
Brassfield limestone on Ludlow Creek.
The general section of Ludlow Creek is continued by the section
of the western wall of the Colonel Samuel B. Smith quarry and the
bank above it, below the house of Patrick Gallagher.
SECTION OF WESTERN WALL OF THE SMITH QUARRY
THICKNESS ee
No. Feet. Inches Feet Inches
26. Laurel limestone-——Top of bank just below
house of Mr. Patrick Gallagher. Light- to
bluish-gray rock in fairly even layers varying
from 2 to 5 inches in thickness. The upper
weathered ones are rather buff and finely
OOKOUS Pen Merwe rare Arline eaayd cua vote: om Reelerstots 3 5 PE So)
25. Partly covered interval. Light- to brownish-
gray, rather thin-bedded, dolomite .......... 2 8 21 5
24. Osgood beds.—Partly covered zone; but at top
bluish-gray shale to shaly limestone......... I 3 18 9
t Journal of the Cincinnati Society of Natural History, XVIII (1896), 182.
338 _ CHARLES S. PROSSER
arcewess py ZORA
No. Feet Inches Feet Inches
23. Brownish- to bluish-gray, thin layer, from 1 to
2 inches thick 4}: 3)) {22 3acee eee ee z= 17 6
22. Bluish-gray shaly limestone to shale, from 6 to 7
inches thick. A specimen of Leptaena rhom-
boidalis (Wilckens) was noted.............0.. 6S ==) iy, 4
21. Dayton limestone—Top layer of western bank
of the Colonel Samuel B. Smith quarry. Light
gray, with rusty spots due to iron pyrite, from
tolH
3 ‘to 4*inches' thick’... 7 ie aes eee tirt ok se 352% #16 n0
go. Layer 2== inches thick? 13 seer eer ese. a= | go 63
19. Layer from 3 to 4 inches thick with dark-gray
blotches inatshipper partes eee. 33 16 Ae
18. Dark-gray irregular bands in the lighter colored
rock. It contains iron pyrite and varies from
4, to5 inches in-thickmess eve ats. ashes ists 45 16 I
17. Light-gray rock without much dark color,
which contains some iron pyrite and varies from
5 to.6 inchésam: thickness tae see ake 5 8
16. Three-inch layer at bottom of more or less
massive zone (Nos. 16 to 21, inclusive), with
average thickness of 1 foot 10 inches at top of
tl
quarry wall on the western and northern sides. . 3 15 3
15. Two rather compact layers, the upper one 4
inches and the lower, 6 inches thick......... ike) 15 °
14. This layer will split up into thinner ones and it
contains iron pyrite 2's fc. tee ae eh 9 14 2
73. ‘Compact layer =: 2 3: aes reese ee 4 13 5
12. This layer may split up to some extent on
weathering sy iat aes ne eee ee oe 9 13 I
11. This layer on weathering splits into various
layers from’ sto’ 5inches thick = ( tO 17 3
15. Light-gray to bluish-gray, compact layer... .. 5 15 5
14. Thin-bedded, light- to bluish-gray zone, with
irregular bedding planes..’:.-5y. cas eerer = 10 rs
13. Compact, light- to bluish-gray layer......... 5 14 2
12. Rather /shaly layer iio... Sage seria A 5 13 9
11. Two compact, light-gray layers, the upper 9
and. the lower 8 inches thick< 2 act jcoesn esc I 5 13
10. Light-gray, shaly dolomite and blue shale... . 6 TE) eae
g. Thin-bedded dolomite splitting into 3 or 4
laverss Wiis atelier eter tetors = I 4 II 5
THICKNESS
on
nN
20 9
Clave sa) Had fas Bicia ines Se See eee eter I 8 ie) I
. Rather coarse, blocky blue shale which forms
the lower part of the shale zone. Nos. 7 and 8
constitute the shale zone in the upper part of
the Osgood beds with a thickness of 2 feet 2
INCHES so elave oc ok DNR RIN a tee ee 6 8 5
a |
THE NIAGARAN FORMATIONS OF WESTERN OHIO — 343
8)
THICKNESS Teacentse
No. Feet Inches Feet Inches
6. Dayton limestone.—Massive zone at top of Day-
ton limestone with a thickness of 2 feet 3 inches,
which splits into 5 layers and the first three in
descending order are from 4 to 5 inches each in
thickness, while the fourth from the top is 8
inches and the fifth 4 inches thick. Light-gray
with blotches and spots of dark-gray, compact
rock with stylolites or hackletooth structur2 at
thelbeddinepplameseiey. seein ces sce. et eiele 2 3 Te
5. Layer of shaly, greenish limestone........... 10 5 8
4. Compact layer of light-gray color with some
‘dark-gray blotches containing iron pyrite and
Call CHC HEE y aU ete te oars Wig Mes I ° Li Sie)
3. Shale to shaly limestone parting............ 2 LO
2. Dark- to light-gray limestone which splits into
Severdlulavenst asin iment aytiki ed we 3 2 3 8
1. To water level in old quarry pit............. 6 6
In the foregoing section, Nos. 7 and 8 correspond to the shale
zone (No.7) of the Ehlers quarry and form the upper member of
the Osgood beds. The Laurel limestone comprises Nos. 9 to 16,
inclusive, with a total thickness of 7 feet 2 inches. The extreme
upper part of this quarry wall shows nearly 3 feet of light-gray
fossiliferous rock which is referred to the Springfield dolomite.
Professor Bownocker has recently published a bulletin on the
“Building Stones of Ohio’’ which contains a section of this quarry.*
In this bulletin the zone called the ‘‘ West Union limestone” corre-
sponds to the “‘ Mottled zone,”’ No. 17 of the foregoing section, and
the upper limestone of the ‘“‘Osgood beds” is what the writer is
correlating with the Laurel limestone of Indiana, and includes Nos. 9
to 16, inclusive, of the foregoing section. The blue shales overlying
the Dayton limestone of Professor Bownocker’s section correspond
to Nos. 7 and 8 of the writer’s section, the top of which he regards
as corresponding to the top of the Osgood beds of Indiana.
GENERAL SECTION ALONG LUDLOW CREEK
A general section of the formations exposed at Ludlow Falls and
in the series of quarries on the northern bank of the stream has been
t Geological Survey of Ohio, 4th Ser., Bull. 18 (1915), Pp. 37-
344 CHARLES S. PROSSER
compiled from the separate sections described above, which shows
the formations from the upper part of the Richmond in the Ordo-
vician system to the lower part of the Springfield dolomite in the
Silurian system. Some of the zones or formations vary in thick-
ness in different outcrops, in which case the variation in thickness
has been given. This necessarily causes a variation in the entries
in the column of total thickness.
GENERAL SECTION ALONG LUDLOW, CREEK
Thickness of Zone
r : Feast Gopaet re ues
or Puneet Names of Series and Formations
Total Thickness
sat toi6r” old ecee ee
hy’ | Springfield dolomite (only lower part shown)
Niagaran Series
| Mottled zone
nm
tae
~
7h Laurel limestone
, |
42)’ to 45y%" | Top of Osgood beds
THY’ to 3%’ Shale zone
|
Aad toast [ee ee ieee oe Dayion limestone
II yy’ Base of Osgood beds
Oswegan Series
26} to 28}’ Brassfield limestone
a? RAS 8 ee ee | Cincinnatian Series
23’ Belfast bed at top of Richmond formation
,
Ol: 1. 2 pibexcee namie se
A mere outline of the classification of the formations of the
Niagaran series along the Ohio-Indiana state line was published
by the writer on April 20, 1915, and the Brassfield limestone was
given in the Oswegan series.”
Correlation of the Brassfield limestone—The limestone in the
foregoing sections, which is called the Brassfield, is the one which in
Ohio has generally been called the Clinton and correlated with the
well-known New York formation of that name, which forms the
* Outlines of Field Trips in Geology for Central Ohio, The College Book Store,
Columbus, Ohio, p. 18.
2 Ibid.
THE NIAGARAN FORMATIONS OF WESTERN OHIO — 345
basal part of the Niagaran series of that state. As early as 18096
Dr. Foerste stated that—
The identity between the Clinton faunae of the two states [Ohio and New
York] on closer examination is not found to be sc close as at first supposed.
Whether this is due to geographical causes, the Clinton of New York being
more litoral, or whether it is due to moderate differences of horizon, can not be
told until the Clinton of New York is much more closely studied. Although
I have been accustomed to call the Ohio formation the Clinton, yet I should
be willing to recognize the fact that the identity is not very marked, by giving
it a name of its own, for instance, the Montgomery formation, on account of its
typical development in Montgomery County, in Ohio.t
In 1906 Dr. Foerste proposed the name Brassfield formation for
this limestone from outcrops ‘“‘along the Louisville and Atlantic
Railroad, between Brassfield and Panola, in Madison County,”
Kentucky.? It was stated that “for the . . . . limestone section
at the base of the Niagaran division of the Silurian, hitherto identi-
fied with the Clinton of New York, the name Brassfield limestone
is proposed.’
After listing the fauna of the Brassfield limestone in Kentucky,
Ohio, and Indiana, and noting the absence in it of certain charac-
teristic Brachiopods of the New York Clinton, Dr. Foerste wrote
as follows:
The identification of the Brassfield limestone of Kentucky, and of its
northern extension in Ohio and Indiana, in former years, with the Clinton
limestone of New York, rests rather upon a somewhat similar facies of
the two faunas, and upon the general absence of the more typical species of
the Rochester shale fauna of New York in these limestones at the base of the
Silurian in Ohio, Indiana, and Kentucky, than upon the presence of any con-
siderable number of species common to both areas. On closer inspection, the
fauna of the Brassfield limestone of Ohio, Indiana, and Kentucky appears to
differ sufficiently from the fauna of the Clinton limestone of New York to
warrant the assumption of the presence of some sort of barrier between these
two areas.4
Dr. Foerste has also stated in a later publication that “the
Brassfield limestone is the southern continuation of the strata
which were identified in Ohio, by Professor Orton, as Clinton.’’s
t Journal of the Cincinnati Society of Natural History, XVIII, 189.
2 Kentucky Geological Survey, Bull. 7, p. 27. 3 [bid., p. 18. 4 [bid., p. 35.
5 Journal of the Cincinnati Society of Natural History, XXI (September, 1909), I.
340 CHARLES S. PROSSER
e |
At the 1912 meeting of the Geological Society of America, Pro-
fessor Charles Schuchert proposed the Cataract formation: ‘‘a new
formation at the base of the Siluric in Ontario and New York,”
from a locality called the Cataract in the Credit River region of
Ontario, 48 miles northwest of Toronto.' In August of the same
year Professor William A. Parks in describing “The Palaeozoic
section at Hamilton, Ontario,” stated that ‘“‘a new formation—the
Cataract— . . . . represents an invasion from the north and west
at the commencement of Silurian time. The upper limestones and
shales of this formation are highly fossiliferous and present a fauna
comparable with that of the Brassfield formation of Ohio and
Kentucky.’”
Dr. Merton Y. Williams described a series of sections in the
Niagara escarpment of Ontario in a paper before the Geological
Society of America in December, 1913, in which he reported that
“the Medina sandstones of Niagara gorge (125 feet thick) are
represented farther north by dolomite and shales (Cataract forma-
tion).’’s
An article by Dr. Kindle on *‘What Does the Medina Sandstone
of the Niagara Section Include ?”’ contains the following sentence:
“The examination by the writer of a number of sections holding
this fauna [Cataract] in connection with a review of the Niagara
section has convinced him that all of the terranes associated with
the Cataract fauna are represented in the Medina of the Niagara
section.’
In a later and exhaustive paper on the “‘ Medina and Cataract
Formations of the Siluric of New York and Ontario,”’ Professor
Schuchert shows the close relationship of the Brassfield fauna to
that of the Cataract formation of Ontario and also “that the
Cataract is a close correlate with the Medina” formation of New
York. In another place is the statement that ‘in other words, the
t Bulletin of the Geological Society of America, XXIV (March, 1913), 107.
2 Guide Book No. 4 (Twelfth International Congress of Geologists), “Excursions
in Southwestern Ontario,” B;, p. 128.
3 Bulletin of the Geological Soctety of America, XXV (March, rgr4), 40.
4 Science, N.S., NXCXTX (June ro, ror4), 918.
S Bulletin of the Geological Society of America, XXV, (September, 1914) 291.
THE NIAGARAN FORMATIONS OF WESTERN OHIO = 347
typical Medina formation shades through lateral alteration into
the typical Cataract.’
This apparently agrees with the idea expressed by Professor R.
Zuber, of the University of Lemberg, on the escarpment at Hamil-
ton, Ontario, in August, 1913,’when he said that the Medina and
Cataract appeared to him to be different facies of the same forma-
tion. Concerning the relation to the Brassfield, Professor Schuchert
wrote:
The Cataract may also be compared with the Brassfield formation of Ohio
and Indiana, as the two are clearly related, and also both are of a limestone
facies. The former has 76 species and the latter 140. Between the two there
are 24 forms in common... . . When the two biotas are finally carefully
compared with each other, there will undoubtedly be added more significant
forms strengthening the view that the Cataract and Brassfield are fairly close
correlates in time. However, as these two faunas are not of the same epicon-
tinental basin, one cannot expect a large percentage of the forms to be common
to both; the Brassfield element came in from the Gulf of Mexico region, while
the Cataract migrated into Ontario through the Gulf cf St. Lawrence embay-
ment across the Province of Quebec or came in from the Arctic
A little later Dr. M. Y. Williams, in his article on the ‘‘Stra-
tigraphy of the Niagara Escarpment of Southwestern Ontario,”
has stated that ‘“‘Medina is used in the sense in which Grabau
has redefined the term, that is, to include the beds above the
(Queenstown shale and below the Clinton formation. It is extended,
however, laterally to include the Cataract formation as defined by
Scehuchert.:3
The Medina sandstone underlies the Clinton beds of New York
and is not included in the Niagaran series, but is the upper forma-
tion of the Oswegan series as classified by the New York Geological
Survey. Therefore, if the correlation reviewed above be accepted,
then the Brassfield limestone (formerly called Clinton) of Kentucky,
Ohio, and Indiana is to be transferred from the Niagaran to the
Oswegan series of the Silurian system.
Furthermore, Professor T. E. Savage believes that in the Mis-
sissippi Valley the Sexton Creek limestone “‘represents about the
t [bid., p. 204. 2 Thid., p. 291.
3 Summary Report of the Geological Survey [Canada] for the Calendar Year 1913
(1914), p. 182.
348 CHARLES S. PROSSER
same general period of deposition as the Brassfield limestone.”*
The Sexton Creek limestone is the upper formation of the Alexan-
drian series, named and described by Professor Savage,” a series
that in Illinois and Missouri contains all the formations between the
Richmond-Maquoketa formation, at the top of the Cincinnatian
series, and the base of the Niagaran series.
Since the above was written, advance pages of a work on
Historical Geology by Professor Schuchert have been received in
which the following correlation appears:
Lower Silurian (Medina, Cataract, and Brassfield formations.
or Oswegan \ Becsie limestone.3
OTHER SECTIONS OF WESTERN OHIO
Sections farther up the Stillwater River toward Covington show
the middle and upper parts of the section exposed along Ludlow
Creek, while those in Covington carry the general section still
higher. Sections farther west, near Lewisburg and New Paris,
agree essentially with those of the Stillwater Valley.
Sections in and near Covington——About two miles south of
Covington is the Jackson Stone Co. quarry, near the Stillwater
River, on the Charles H. Jackson farm. It is easily reached by the
Piqua, Covington, and Dayton trolley line, leaving the car at stop 45,
which has the name of Sugar Grove. The section given below is
of the eastern wall of the quarry, the top of it near the engine
house, a short distance southwest of the crusher.
SECTION OF THE JACKSON STONE CoO. QUARRY
THICKNESS eee
No. Feet Inches Feet Inches
22. Cedarville dolomite-—Buff, mostly porous, crys-
talline dolomite, with Pentamerus oblongus
Sowerby common all through the outcrop.
Zone at base with large number of specimens
of Pentamerus oblongus Sowerby as well as
Favosites niagarensis Hall. ...............-. 3 8 109 9
I Illinois State Geological Survey, Bull. 23 (1913), Pp. 33.
2 American Journal of Science, 4th Ser., XXV (1908), 434, 443; Illinois State
Geological Survey, Bull. 23, pp. 14, 15.
3 A Text-book of Geology, Part II, Historical Geology (1915), p. 661.
No.
21.
20.
IQ.
18.
17e
16.
4.
THE NIAGARAN FORMATIONS OF WESTERN OHIO
Springfield dolomite.-—Buff-colored, rather thin,
layers of even-bedded dolomite. The layers
vary in thickness from 2 to 8 inches and the
majority of the layers are probably from 4 to 6
inches thick. No one of the exposed layers is
blue. Fossils, as Pentamerus oblongus Sowerby,
and corals are common and certain layers con-
tain numerous specimens of Pentamerus ob-
longus. ‘This zone, with its thin even beds of
buff color, has clearly the lithologic appearance
of the Springheld dolomite: ) 5255.5... 05. 242
Bluish-gray, weathering to a buff color, rather
compact, slightly porous, dolomite which gener-
allyssplitswmto\twolayersiac:2c).)..). 2.00 Jeo)
Bluish-gray, somewhat mottled, layer which
Containssbut tewstossilstmens qc. .s seo
Bluish-gray layer, fairly compact, in part sub-
crystalline, with some small holes and contain-
ing large numbers of Pentamerus oblongus
Sowerby. On account of the large number of
fossils this zone may be called a Pentamerus
layer and clearly belongs in the Springfield
GKENGICAMIYS 5c, Hide Gite ih ain GuSeNS Ieee Neer A
Motiled zone.—Massive layer of bluish-gray
dolomite marked with large, irregular-shaped
spots of light-gray color, so that the entire sur-
face has a coarsely mottled color. It has a
porous structure with medium-sized cavities.
It contains some fossils, as, for example, cup -
corals and crinoids, with an occasional specimen
of Peniamerus. At the base is a stylolites part-
Laurel limestone.—Lithologically like lower
layers, thickness varying from 9 to ro inches,
more porous in upper 4 inches, with small and
larger holes. Some fossils, as a cup coral and
LEG HOTIGLUSG 9.5 Se tii es Sa Re MRE RE Eee
. Bluish-gray, somewhat porous, limestone. A
CUprcoralpwasimotediyy jr mera my. 5.0 rae
Layer of light-gray mottled with dark-gray,
fairly compact, limestone, varying in thickness
HOM PA VLOMTGh IM CHES ewes vrene sre toe ciscccs eich
THICKNESS
Feet Inches
Io 6
I 2
105
Io
ii 2
1
oz=
Io
I z+
349
TOTAL
THICKNESS
Feet Inches
106 I
95 Uf
94 63
Q3) aS
92 10
85 8
84 10%
84 2
350 CHARLES S. PROSSER
" TorTraL
THICKNESS THICKNESS
‘No. : Feet Inches Feet Inches
13. Light-gray limestone in 4 layers, with shaly
partings, varying in thickness from 19 to 21
inches. Lithologically similar to subjacent
layers . hc. iS bak cnievec Rae eee epee I 8+ 83 °
12. Light-gray, with dark-gray spots and blotches,
compact limestone, which is harder than lower
layers and varying in thickness from 12} to 13
INCHES «y's lace bak We AI tee i fu: = Sr 32
11. Gray, weathering to a brownish color, gritty
shale, about’ r.inch: thick ino. aot sateen os. x 1 = 80 3
ro. Layer lithologically about the same as the sub-
jacent OME. < achcos ccc’ ee eRe et ede
491°" an
Ww
Io
(os)
fon
>
On
Bate
Light-gray, compact course.........-- Ga
12.
Il.
THE NIAGARAN FORMATIONS OF WESTERN OHIO
base of the mottled zone and the top of the
Osgood shale is about the same in all three sec-
TSR TERED Wislentiste/aielelansnlc
Laurel limestone-——The following courses all
have a bluish-gray color when seen on fresh
surface:
Light-gray, compact course.......---- Aa
Light-gray course, the upper part
blotched with dark-gray spots, but not
many in lower part........----+---- 8
Shaly limestone parting. ......------- <-1
Light-gray, compact layer.........--- 8
Light-gray course, with dark-gray spots
and bands which tend to split into 2
AWA so nig bb babiooeeesosocdeaenMe avr ats)
ight-oray, layenun ie. « aoa) 9-92
Very mottled light- and dark-gray, thin
ANE 6 Soup des bavbansesnowooocueOn Ze
Light-gray layer..........-----++-+:- ie)
Similar to above layer with a broken
parting at base.........--++----+--> 8
Bluish-gray layer with dark-gray streaks
HAG NOUS, obeccseesaaecseneecocoous 6
The total thickness of the above layers varies
from s feet 103 inches to 6 feet 2 inches.
The three following layers are of light-gray
color with dark-gray spots, blotches, and
streaks and have about the same lithologic
appearance:
Feet Inches
Idle JERE oo oo Kaboom ea don oO oUOK I 3
Secondilayerme aes] oe ie)
Compact, massive layer containing
calcite) crystalsy. 222.522 ---5-5---- 2 I
Osgood beds.—Bluish-gray, soft shale which
forms the floor of the quarry. Six inches or
more are shown in the quarry. Mr. Robert
Mollett, foreman of the quarry, stated that at
the time of the March flood of 1913 the shale
was shown by the side of the railroad track
THICKNESS
Feet Inches
4 I
§=5 ©
4 2
Syl
TOTAL
THICKNESS
Feet Inches
33 9
29 8
23 8
Io.
Q.
wy
Os
below the crusher and varies in thickness from
2 feet 6 inches to ¢ feet. cosh eens tins
Dayton limestone.—Mr. Mollett stated that the
upper surface is somewhat uneven and that the
limestone extends about 1 foot higher than
the top of the exposed ledge on the south bank
of Twin Creek below the Lewisburg Stone Co.
crusher.
Upper foot, according to Mr. Mollett, not ex-
POSE. ck eee ee
Light-gray layer, very rusty colored from
weathered iron pyrite. Varies in thickness
from ‘r ‘to:ak INChes ones eee ee
Mostly light-gray, thin-bedded to shaly, lime-
C1 KO) 0 RE a TE ies cho Choe wank ce eh AG een c
. Thin layer of more or less crystalline structure,
Which:containS 1OSSIIS wa eee eee eee
. Bluish-gray, thin-bedded layers, weathering to
a very light-gray or whitish color. Rarely thin,
somewhat irregular, finely crystalline layers in
which is an occasional fossil. ...............
. This zone will split into 3 layers. ‘The upper
one contains much pyrite and has weathered in
spots to a very rusty color. The middle and
lower parts of light-gray color with spots and
irregular layers of dark-gray color from iron
PYTICEN Fe CRs RS Pe ees
. Light-gray to bluish-gray, rather thin-bedded
layers on bank of creek, with slightly glistening
surface. Upper part of zone contains imperfect
BrachiGbods scis..5% Shacsa ao eee
. Light-gray, compact layer which is harder than
rock above. Base at creek level on Septem-
BOP TOG Sh oon 5 x ical v4 an te
. Two thin layers of compact, bluish-gray rock,
the upper one 2 inches and the lower one 23
ches thiee s. 4 vou. tess eee Rte ew igs
. Brassfield limestone —The upper surface rough.
Mottled pink and gray crystalline limestone in
bed of creek, just below the bank of Dayton
limestone. In the bed of the creek 13 inches
CHARLES S, PROSSER
THICKNESS
Feet
to
Inches
Io
~]
bol
TOTraL
THICKNESS
Feet Inches
19 6
16 re)
15.) "Gee
ee
14 867
14
oe
wn”
nm
role
ws
bol
THE NIAGARAN FORMATIONS OF WESTERN OHIO 359
THICKNESS cae
No. Feet Inches Feet Inches
of Brassfield limestone was measured; but it
extends on down the creek and a quarryman
stated that about 8 feet is shown along the
CLEC Kite oe nn Lea eaR agen ess) oe 2 otmanal 8= oO 8 °
A view of the southern wall of the Lewisburg Stone Co. quarry
is shown in Fig. 2. The lower part of the wall is the Laurel even-
bedded limestone, the top of which Mr. Cottingham is indicating
by the hammer, above which is the conspicuous ‘“‘mottled zone,”
and above this zone is the Springfield dolomite:
In the foregoing section the Laurel limestone is called the “blue
building stone” by the quarrymen and comprises Zones 12 and 13
with a thickness of about 1o feet 2 inches. A section at a different
part of the southern quarry wall gave a thickness of g feet 10
inches. It is well shown in the picture of the southern wall of this
quarry (Fig. 2) where Mr. Cottingham is marking its top with the
hammer. Samples of the Laurel limestone from the southern wall
of this quarry were analyzed by Professor Demorest with the
following result:
Silicious Residue | Fe.0; and Al.0; CaCO;
MgCo,
8.85 1.20 56.00 BO) Ot
The massive ‘“‘mottled zone,” with a thickness of 4 feet 1 inch,
immediately above the Laurel limestone, is also well shown in
Fig. 2. Samples from this zone in the southern wall of the quarry
were also analyzed by Professor Demorest with the following
result:
Silicious Residue | Fe.O; and Al.O3 CaCO; MgCO;
ary 0.75 BA pL2 42.13
2.55 0.80 54.12 42.31
The following analysis by Professor Demorest of samples of
the West Union limestone from Sproull Ravine, about 14 miles
360 CHARLES S. PROSSER
northeast of Duncanville and 73 miles northeast of West Union,
Adams County, is given for comparison with that of the ‘‘mottled
zone:”’
SiO, Fe:O; and ALO, CaCO, MgCO,
20.24 | 4.05 44.67 290.14
It will be seen from these analyses that the West Union is a
much more silicious rock than the “‘mottled .zone”’ and that the
latter is a dolomite. It is to be noted that the chemical composi-
tion and lithologic character of the ‘‘mottled zone” differ consider-
ably from those of the West Union limestone in its typical region.
The rock between the first and second cap rocks of the quarry-
men is called by them the ‘buff building stone” and corresponds
to Zones r5 and 16 of the last-given section, all of which evidently
belongs in the Springfield dolomite.
All the rock above the shale zone (No. 11) of the Osgood beds
is quarried and crushed for concrete and road material. The fine
rock, which the men call “‘sand,” binds well on the roads, and it was
stated that the entire product of the quarry for 1914 was used on
the Ohio roads by the State Highway Commissioner.
Dr. Foerste some years ago published a brief description of the
Weaver quarries, located on the northern side of Twin Creek, oppo-
site the eastern part of the Lewisburg Stone Co. quarry. Recently
Professor Bownocker has published a section of the Lewisburg
quarry in which the upper limestone of the Osgood beds with a
thickness of 9 feet 11 inches corresponds to the Laurel limestone of
the last-given section.? The 3 feet of blue clay beneath is the
Osgood shale and the subjacent 1o feet of ‘‘blue-gray limestone”
the Dayton. The ‘‘West Union limestone,” 43 feet thick,> corre-
sponds to the ‘‘mottled zone” of the last-given section, overlying
which is the Springfield with a thickness of 8 feet and then the
Cedarville which forms the highest part of the quarry. Apparently
the line of division between the Springfield and Cedarville dolomites
* Journal of the Cincinnati Society of Natural History, XVIII (18096), 183, 184.
2 Geological Survey of Ohio, 4th Ser., Bull. 18 (1915), p. 40.
3 Ibid., p. 39.
361
THE NIAGARAN FORMATIONS OF WESTERN OHIO
snonoidsuod ay} St sUOJSOWT Janey] oy} 2
qied IMO] ay, “OIyO ‘SInqstMo'T Jo JSoMTIIOU oTTU ou
AOqY
‘ayWMOTOP ppeysurds ay} st yTyM SutAj19A0
‘IoWUIeYy 94} AQ poyYIeUr st YOIyM Jo do} ay} ‘
,¢9U0Z poa]}jOUr,,
QUO}SIUN] JOINe'T IY} SI
‘Arzenb °07) 9u01¢ SanqsimeT 9 O ]]/eM WINyIN0G—*z “OIF
) S qSIMa'T 9} Jo T {INOS A
362 CHARLES S. PROSSER
is drawn at the same horizon as the top of Zone 16 in the writer’s
section, which gives a thickness of 8 feet 7 inches for the Spring-
field or 8 feet as measured by Professor Bownocker.
SECTION NEAR LAUREL, INDIANA
In the foregoing sections the correlation of the terranes referred
to the Osgood beds and the Laurel limestone, both of which were
named by Dr. Foerste,* was decided upon after visiting Laurel,
Indiana, and studying some of his sections in that typical region.
A section at one of these localities, in a somewhat condensed form,
is given below. The section is on the bank of a stream at a locality
known as Derbyshire Falls, on the C. J. Valkenburg farm, nearly
3 miles southwest of Laurel and some 47 miles southwest of the
Lewisburg Stone Co. quarry. A section of the Laurel limestone,
Osgood beds, and Clinton limestone measured at this locality and
the Lower Derbyshire Falls was published by Dr. Foerste in 1898.?
The measurements in the following section are those of the writer
and his assistant, Mr. Kenneth Cottingham; but the classification
is in accordance with that of Dr. Foerste, except where differences
are noted:
DERBYSHIRE FALLS SECTION
THICKNESS Tee
No. Feet Inches Feet Inches
18. Laurel limestone—This limestone is shown in
the old quarry just across the quarry road to
the south of Derbyshire Falls and this zone
extends to the top of the quarry wall. It is
light gray, as weathered, rather thin-bedded,
the layers varying from 2 to 8 inches in thick-
ness. There are also at least 3 chert layers
ranging from 1 to 3 inches in thickness....... 4 7 52 °
* Osgood beds: Indiana Department of Geology and Natural Resources, 21st Annual
Report (1897), pp. 217, 227-29.
Laurel limestone: Journal of the Cincinnati Society of Natural History, XVIII
(February, 1896), pp. 190, 191, and Indiana Department of Geology and Natural
Resources, 21st Annual Report (1897), pp. 217, 230, 231.
2 Indiana Department of Geology and Natural Resources, 22d Annual Report (1808),
pp. 244, 245. An illustration of Derbyshire Falls is given on Pl. XVI, which faces
Pp. 244:
No.
i
16.
is,
14.
13.
2.
If.
Io.
THE NIAGARAN FORMATIONS OF WESTERN OHIO
Thicker layers of compact limestone, light gray
to buff, when weathered, with shaly partings.
The majority of the layers are perhaps 3 to 5__
inches in thickness; but there are thicker ones
which apparently range from 8 to 14 inches.
No chert was noticed in this zone...........
?Top of Osgood beds.—Buff, compact, 8-inch
layer at top of ledge on south side of falls, which
is apparently the one across the quarry road in
the base of the old quarry at the spring. The
top of this layer is apparently the horizon where
Dr. Foerste has drawn the line of separation be-
tween the Osgood beds and Laurel limestone.
Lithologic characters, however, in the vicinity
of Laurel would apparently favor classing it
withthe Iaurel limestones. ....2..-..--..<
Blue, argillaceous, soft shale or clay. This is
the blue-clay stratum of Dr. Foerste.........
Shaly, light-gray limestone................
Light-gray, compact, even-bedded limestone;
some of the bedding planes rather rough. The
layers vary in thickness from 5 to g inches, and
perhaps the majority of them average about 8
inches. This is the Lower Quarry or Osgood
rock of Dr. Foerste, and is apparently the con-
tinuation of the Dayton limestone in Indiana
Brassfield limestone.—Light-gray, crystalline
limestone. Apparently the upper foot and 3
inches of this zone was regarded by Dr. Foerste
as a “‘doubtful horizon: White Clinton or base
ofiNiagara rocks? Gin en haere Payee ees 2
Crystalline gray to pinkish limestone. It is
very irregularly bedded and contains pyrite, so
that it is frequently rusty colored on the
weathered surface. Dr. Foerste’s section re-
ports ‘‘Clinton; 7 feet 6 inches; reddish”’....
Richmond formation.—Light-gray, impure lime-
stone with portions that are darker colored...
. Gray, impure limestone, the upper layer a foot
thick separated by a shaly parting from a lower
layer of similar limestone, 1 foot 3 inches thick
THICKNESS
Feet Inches
5 3
8
I 6
4
Oa
2 3
Oly
I 6
2 3
363
TOTAL
THICKNESS
Feet Inches
47 5
42 2
41 6
40 fo}
fo ain,
33 4
Bia I
24 6
23
364 CHARLES S. PROSSER
THICKNESS Tee
No. Feet Inches Feet Inches
8. One layer of gray, massive, impure limestone.
No fossils seen, 4 6... Ga Oe Sertraline cx 4 fo) 20 fe)
7. Layer similar to one above. .iie¢...60..55.- 2 2 16 9
6. Massive, light-gray layer with dark-gray spots.
No fossils noted).<\/c. See ree eios tak ee 3 ° 14 7
5. Shale parting GO. > Jin meee mere eres 3. I II 7
4. Grayish, somewhat crystalline, limestone which
tends to split into thinner layers............ ) Il 6
3. Bluish shales alternating with gray, fossilifer-
GUS LIMeOSEOME :s:/c5-.icicrs ete eI ecdeos FR 2 3 ate) 9
2. Grayish, somewhat crystalline, limestone, hard
and ‘very fossiliferotiss eee os ee. SS cals 5 4 8 6
1. Grayish to bluish shales which are not very
fossiliferous.< (Foot or falls es yoatce es cae a 3 2 3 2
In the foregoing section Zones 11 and 12, with a thickness of
8 feet ro inches, have been classed together and considered the
western continuation of the Brassfield limestone of Ohio. Zones 13
and 14 of light-gray limestone with a thickness of 6 feet 8 inches
are considered the western continuation of the Dayton limestone
of Ohio. Dr. Foerste has stated that ‘in Ohio Pentamerus oblongus
occurs in the Dayton limestone, equivalent to the base of the
Osgood bed.’’* The soft blue shale or clay of Zone 15 is believed
to correspond to the blue shale of Zone 11 in the Lewisburg Stone
Co. quarry and the shale at the same horizon in the various quarries
along the Stillwater River. As stated above in the description of
the section, the lithologic break occurs at the top of this shale,
which appears to the writer from the sections which he has studied
to be the horizon where he would draw the line of division between
the Osgood beds and Laurel limestone. If the 8-inch layer of
compact, buff limestone (No. 16) immediately above the soft blue
shale zone be classed with the Laurel limestone, then ro} feet of
it are shown in the wall of the old quarry on the bank above and
south of the falls. It is believed to be the eastern continuation
of this limestone which makes Zones 12 and 13 with a thickness
of ro feet 2 inches in the Lewisburg Stone Co. quarry and the
t American Journal of Science, 4th Ser., XVIII (1904), 341.
THE NIAGARAN FORMATIONS OF WESTERN OHIO — 365
limestone which has been called the Laurel in the sections farther
east along the Stillwater River.
Samples of the Laurel limestone were collected at the quarry
above Derbyshire Falls and analyzed Bx: Professor Demorest with
the following result:
SiO. FeO; and ALO; CaCO; MgCo;
17.84 I.00 47.89 31.54
This analysis shows that the Laurel limestone at Derbyshire Falls
is a more silicious one than that at the Lewisburg Stone Co. quarry ,
which contains but 8-85 of silicious residue. On the other hand,
the Lewisburg stone contains a larger percentage of CaCO,, where
it amounts to 56 per cent of the rock; the other constituents at the
two localities do not differ to any marked degree.
ORIGIN OF THE LYMAN SCHISTS OF NEW HAMPSHIRE
FREDERIC H. LAHEE
Massachusetts Institute of Technology
TABLE OF CONTENTS
: PAGE
INTRODUCTION. , 3 % « SEE Cs 4 os Ne
SUMMARY oo o) 0) QpteRUee eens A 3. | ll
TEE LISBON AND LYMANISERIES (7705 5 450. 6) 4s 4 2
GENERAL DISTRIBUTION OF THE LYMAN SERIES... . . . . 369
Frecp Retations AND MerGAscopic DESCRIPTIONS OF THE LYMAN
SERIES
The Young’s' Pond Locality." ek ws Le
The Mormon: Bill Locality “ark Ge kk
The Parker Hull Locality. "cage ehh) ss
Microscopic DESCRIPTIONS
Porphyry Schist of the Young’s Pond Locality . «4
Pebbles of the Conglomerate Schist of the Young’s Pond Locality . 374
oy
Parker Hill White Schist . SAdss ey ek ioe NS Goya 5
Parker Hill Dark Schist #S) si ixie ees he ae) cs 8s a a
GENERAL CONCLUSIONS ON THE ORIGIN OF THE LYMAN SCHISTS
Porphyry Schist of the Young’s Pond Locality . . ... . . 377
Patker Fill “White Schist ~) “2 cite ee x
Conglomerate Schist of the Young’s Pond Locality . . . . . 3790
STRUCTURAL RELATIONS OF THE LYMAN SERIES... . . . . 380
Acipic ErFrusIve Rocks EAst OF THE APPALACHIAN PROTAXIS . . . 380
INTRODUCTION
During the summers of tort and 1912, through the generosity
of Mr. R. W. Sayles, I made a geological investigation of part of
the townships of Littleton, Lisbon, Lyman, Bethlehem, Bath, and
Landati, in New Hampshire. In the fifteen weeks devoted to this
work about 250 square miles were examined. The results that have
been published' have reference to an area of only eight or nine
square miles (Fig. 1), in the study of which three of the fifteen
«F. H. Lahee, “Geology of the New Fossiliferous Horizon and the Underlying
Rocks, in Littleton, New Hampshire,” Am. Jour. Sci. (4), XXXVI (1913), 231-50.
3 60
THE LYMAN SCHISTS OF NEW HAMPSHIRE 367
weeks were consumed. ‘The survey of the rest of the area amounted
to a reconnaissance of intricately metamorphosed schists, regarding
which final conclusions were deferred until more could be learned.
Having had opportunity to revisit some parts of the field where the
“Lyman schists’”’ are exposed and having examined a suite of thin
sections of these schists, I submit the present paper as a second
chapter on the geology of the ‘“‘Ammonoosuc District.”
Fic. 1.—Index map of the localities mentioned in the text. The shaded rec-
tangular area. is the strip of country described in the article on the Littleton
fossiliferous horizon. 1, Blueberry Mountain. 2, Bald Hill. 3, Young’s Pond.
4, Partridge Lake. 5, Parker Hill. 6, the “Parker Hill locality.” 7, Lyman village.
8, Black Mountain. 9, the “Black Mountain locality.” 10, Mormon Hill. 11, Lit-
tleton. 12, Lisbon. Only a few roads are drawn.
I am happy to express my gratitude to Mr. W. L. Whitehead,
a candidate for the doctorate of science in geology at the Institute,
for making the accompanying microphotographs, and to Mr.
Sayles for the use of Figs. 2 and 15.
SUMMARY
1. The term ‘“‘Lyman schists’? was applied by Hitchcock to
a group of schists many of which are characteristically whitish on
their weathered surfaces.
368 FREDERIC H. LAHEE
2. These Lyman schists are broadly exposed in the area north-
west of the Blueberry Mountain—Bald Hill range and its south-
westward extension.
3. Hitherto the Lyman series has been regarded as a group
of metamorphosed sedimentary rocks.
4. Field evidence, megascopic examination of hand specimens,
and microscopic examination of thin sections indicate that the
Lyman series contains interbedded members which appear to be
of volcanic origin.
5. These metamorphosed volcanic rocks include, among others,
species related to the quartz keratophyres and the keratophyres,
and probably also tuffs and agglomerates of similar composition.
6. It seems more reasonable to attribute the origin of the coarse
conglomerate schist near Young’s Pond, Lyman, to vulcanism
than to glaciation.
7. The association of acidic effusives with the Paleozoic rocks
east of the main Appalachian protaxis is not exceptional for New
Hampshire. Such effusives are found in Maine, in the Maritime
Provinces of Canada, and in the Piedmont Plateau of our middle
and southern Atlantic border states.
THE LISBON AND LYMAN SERIES
On the northwestern side of the Blueberry Mountain formation"
are highly metamorphosed greenish and whitish schists which out-
crop over many square miles. The greenish varieties are often
chloritic. They and certain other associated rocks were called
by Hitchcock the “Lisbon group.”’ The whitish schists belong
to his ‘Lyman group.” In his earlier reports he relegated these
two formations to the Huronian,? the Lyman group being con-
sidered the younger member; but subsequently he referred them
to the Cambrian or to the Ordovician,’ and concluded that “the
Lyman schists . . . . do not represent a stratigraphical terrane”’;
the term “is a petrographical designation.’”
*F. H. Lahee, op. cit.
2 C. H. Hitchcock, Geology of New Hampshire (1877), I, 277.
8 Ibid.; Geology of Littleton, New Hampshire, reprint from the History of Littleton
(1905), pp. IX, 20.
4 Ibid., p. 31.
THE LYMAN SCHISTS OF NEW HAMPSHIRE 369
GENERAL DISTRIBUTION OF THE LYMAN SERIES
No attempt will be made here to mark out the exact distri-
bution of this series. It is exposed over broad areas west of the
Blueberry Mountain Siluro-Devonian belt and it may be related
to schists on the east of this belt. The principal localities (Fig. 1)
to which reference will be made in the sequel are Mormon Hill,
the valley just northwest of Young’s Pond, and Parker Hill.
Lyman schists are also exposed on the hill southwest of Young’s
Pond, on the lower eastern slope of Black Mountain, near Partridge
Lake, and elsewhere in the broad valley between Gardner Mountain
and the Mormon Hill-Parker Hill range. In all these places the
group has a breadth of outcrop of several hundred feet, the rocks
are schistose, the strikes are roughly northeast-southwest, and the
cleavage and the bedding (where visible) have steep dips.
FIELD RELATIONS AND MEGASCOPIC DESCRIPTIONS OF THE
LYMAN SERIES
The Young’s Pond locality—Near a small schoolhouse about
one-third of a mile northwest of Young’s Pond is a large outcrop
of a conglomeratic schist which we used to speak of as the ‘“school-
house conglomerate” (Fig. 2). It is the rock which Mr. Sayles
has recently described as possibly being a tillite.". This conglom-
erate schist appears to rest unconformably upon a whitish or light-
grayish porphyritic sericite schist. The contact, which is very
irregular, runs northeast-southwest and may be seen not only near
the schoolhouse, but also, a few hundred feet southwest, near the
brook that flows into Young’s Pond. ‘The conglomerate schist is
on the northwest, the porphyry schist on the southeast, of this con-
tact. The conglomerate schist is between 300 and 400 feet wide
across the strike, and the porphyry schist is between 150 and 250
feet wide. This statement should not be understood to imply
that these rocks have no variation across their outcrop belts.
There is evidence that the porphyry is interrupted at least at one
horizon by a bed of fine conglomerate schist.
West of the “schoolhouse conglomerate”’ is a series of whitish
rocks including fine, non-porphyritic schists, fine porphyritic
«R. W. Sayles, ‘‘Tillite in New Hampshire,” Science, N.S., XLI (1915), 220.
370 FREDERIC H. LAHEE
schists, tine conglomerate schists in which the pebbles and paste
are of similar whitish materials and the pebbles are much sheared,
and schists of the texture of medium sandstones. The last-
mentioned material and some of the finer conglomerate schists
looked so much lke altered pyroclastics that they were called
tulls in the field. (See description of the Parker Hill white schist,
below.) All these rocks are exposed more than once across the
strike.
The porphyry schist that underlies the -“‘schoolhouse con-
glomerate”’ has an exceedingly fine groundmass, which is sericitic
and in places rich in
chlorite. The pheno-
crysts, ranging up to
nearly 3 inch in diam-
eter, but averaging
$-i5s inch, are of
quartz and plagio-
clase. They are uni-
formly distributed
and constitute about
Lyman (‘schoolhouse’) conglomerate, half of the rock. The
showing obscure outlines of pebbles. The dark masses, .
cee a ee ocak tas at a eee “quartz has a very high
edged with black enamel, are of the fine drab schist. ; Sc oe
Photograph by Mr. Sayles. luster, is somewhat
| bluish and very trans-
parent, and has tendency to break with a rude cleavage. The
plagioclase is so fresh that the striations are distinct and the frac-
ture surfaces are brightly reflecting. The shearing of the rock
seems to have been localized in the groundmass. Within its own
mass this schist has no bedding.
The conglomerate schist (“schoolhouse conglomerate’’), also,
is quite devoid of bedding. It contains many large and small
fragments of the porphyry schist, together with pieces of other
whitish rocks of the Lyman series, and masses of rust-brown,
smooth-looking schist, which are conspicuously darker than the
Lyman varieties. All the pebbles have been more or less sheared
and in such a way that their longest axes are parallel with the
dip of the cleavage. Some seem to have been roundish, but more
Fic. 2.
THE LYMAN SCHISTS OF NEW HAMPSHIRE Dia
often they were obviously angular. Naturally the shearing has
increased the irregularity of their shapes.
The quartz-plagioclase porphyry pebbles have been deformed
less than the other varieties. Their average dimensions may be
expressed by the ratio 2:1.25:1. They range up to two feet in
length.
The dark fragments, mentioned above, are often drab-colored
on the weathered surface, but dark-greenish when fresh. As will
be explained presently, they are chlorite and actinolite schists.
They are of medium fine grain and of uniform texture, they are
markedly sheared, and their shape is very irregular, even jagged.
Some were found to be ro or 12 feet long and only 1 or 2 feet wide.
Others are less elongate (Fig. 2).
As compared with the pebbles, the paste of this conglomerate
schist is in relatively small amount. Nor does it seem to have
been derived from an argillitic substance. It looks rather as if
it had been fine clastic débris, of texture ranging from fine sand-
stone to fine conglomerate, derived from the same sources whence
came the larger pebbles. Its appearance is that of metamorphosed
tufaceous material. Partly on account of the metamorphism and
partly because of similarity of character, the paste is not sharply
defined from the pebbles. On fresh surfaces of the rock the pebbles
are distinguished with difficulty, and even on weathered exposures,
where the psephitic structure is best brought out, the details are
blurred.
The Mormon Hill locality—On a traverse across the strikes
on Mormon Hill, one passes over a series of schists much like those
near Young’s Pond. ‘They are porphyries, tuff-like clastic rocks,
and fine and coarse psephites, all sheared. They dip steeply north-
west. In one place obscure cross-bedding indicated that the
stratigraphic sequence was younger westward; and in another
locality the same fact was shown by an unconformable contact
between tuff-like schist on the southeast and conglomerate schist
on the northwest. The series was roughly measured as having
a breadth of outcrop of 800 feet.
The porphyry schist of this region differs from that near Young’s
Pond in lacking quartz phenocrysts. Its phenocrysts are all of
372 FREDERIC H. LAHEE
plagioclase. Otherwise, in respect to size, abundance, and arrange-
ment of phenocrysts and characters of the groundmass, it is mega-
scopically like the type above described.
The coarse psephitic rocks here contain fragments of whitish
and drab schists, as at Young’s Pond.
The Parker Hill locality.—Por-
phyry schists, tuff-like schists, and
psephite schists are here exposed in
a belt several hundred feet wide.
The porphyry schists are finer than
the Young’s Pond type. Along the
road that crosses Parker Hill between
Lisbon and Lyman villages exposures
near the top of the hill exhibit curi-
ous relations. A dark-gray schist
Fic. 3.—Rounded plagioclase (called hereafter the Parker Hill dark
phenocryst surrounded by ground- schist) is associated with a whitish
Tae lice ee ain se rock of the Lyman series. The latter,
imperfections on the negative. which will be called the Parker Hill
white schist, in several outcrops, con-
stitutes a matrix in which are scattered
large and small irregular blocks and strips
of the dark schist, many being greatly con-
torted. The phenomenon resembles intra-
formational pebbles in clastic material.
The white schist is of the texture of a
medium sandstone. Quartz and feldspar
are both abundant and the interstices
between the larger grains are filled with finer
particles ot quartz and feldspar, together chenéect Thee
with secondary mica. The dark schist is ines indicate the arrange-
phyllitic. Some specimens of it have mi- ment of mica laths. En-
nute phenocrysts in a still finer groundmass. @tged_ 16 diameters.
Fic. 4.—Broken quartz
MICROSCOPIC DESCRIPTIONS
Porphyry schist of the Young’s Pond locality —Thin sections of
the porphyry schist from near the schoolhouse northwest of Young’s
Pond show a nearly uniform groundmass. The diameters of the
THE LYMAN SCHISTS OF NEW HAMPSHIRE aya
smaller phenocrysts are thirty or forty times those of the larger
groundmass grains and there. is no gradation between the two
(Fig. 3).
Clear, but with a few vacuoles, the quartz phenocrysts display
only slight crushing, and this is mostly peripheral (Figs. 4-7).
Their corners have been rounded. Several individuals are invaded
by long narrow bays of the groundmass (Figs. 5 and 8). It is
worth while noting that, although the outer borders of these pheno-
crysts are jagged on’ account of granulation
and penetration by mica laths, the edges of
the embayments are clean-cut and smoothly
curving.
\\ee7 ff
Z
Fic. 5 Fic. 6 Fic. 7 Fic. 8
Fic. 5.—Quartz phenocryst with edges serrate on account of marginal granu-
lation and penetration by mica laths. Note smooth outline of the embayment (a).
Enlarged 26 diameters.
Fic. 6.—Detail of outer edge of the quartz phenocryst represented in Fig. 5.
The shaded area is quartz (Q). The small laths are mica (M/).
Fic. 7.—Quartz phenocryst showing terminal granulation at pole of minimum
compression (¢). a-—b is the edge of the thin section. Enlarged 20 diameters.
Fic. 8.—Part of a large quartz phenocryst. The border zone, a—b, is a granu-
lated portion of the phenocryst. Outside this zone is the much finer, uniform ground-
mass (not figured). Several embayments of the groundmass are shown, one cut
longitudinally (¢), and the others intersected transversely at various angles. Note
regular outlines of these embayments as compared with the jagged border of the grain
as a whole. The figure is drawn from a microphotograph, but not with absolute
precision in the finer details. Enlarged 16 diameters.
Like the quartz, the plagioclase phenocrysts are not severely
crushed (Fig.9). The angle of extinction on sections approximately
perpendicular to the albite twinning varied between 13° and 17°.
This and the fact that the index of refraction was always lower than
that of balsam indicate that the mineral is albite. Some grains
have very good crystal outlines (Fig. 10), but as a rule they have
had their corners more or less rounded (Fig. 3).
374 FREDERIC H. LAHEE
As for the groundmass, it consists of abundant quartz and
chlorite, with some sericite and feldspar. It is so fine that micro-
scopic discrimination between quartz and feldspar is almost
impossible. Both chlorite and sericite show some tendency to
parallel arrangement. The chlorite is likely to occur in larger flakes
in the lee of the phenocrysts and in
the quartz embayments—in other
words, where there was some protec-
tion from the shearing stress, such
as it was. Neither quartz nor feld-
spar phenocrysts contain scattered
inclusions of the groundmass.
The porphyry from the channel
of the brook running into Young’s
Pond is somewhat more sheared than
Fic. 9.—A plagioclase pheno- that from the schoolhouse ledge. The
cryst showing the bundles of seri- quartz and feldspar phenocrysts are
cite laths that wrap round it at : :
the poles of maximum compression. more strained and granulated, and in
Enlarged 11 diameters. some places the broken fragments
are separated by a strip having cata-
clastic structure (Fig. 11). Sericite is more
abundant and has better orientation. It is
often thickly plastered against the pheno-
crysts about which it wraps at the poles of
maximum compression (Fig. 9). In other
respects this schist is similar to the less meta- Fie, 16.2—-Plawioelaee
morphosed specimens. phenocryst with zonal
Pebbles of the conglomerate schist of the SE
Young’s Pond locality—FPebbles of the por- ted ort eae Bs
phyry schist are identical with the bedrock js somewhat decayed.
of thesame. They need no further descrip- Enlarged 32 diameters.
tion here.
The dark masses which have been mentioned as greenish when
fresh, but drab when weathered, are of peculiar interest, since
they have been regarded as highly metamorphosed blocks of argil-
lite. They have been compared with the slate blocks in the Squan-
tum tillite.t. Thin sections were prepared from several fragments
*R. W. Sayles, op. cit.
THE LYMAN SCHISTS OF NEW HAMPSHIRE 375
taken from different outcrops of the ‘schoolhouse conglomerate.”
Microscopic examination revealed two distinct varieties. One is
composed largely of zoisite and bundles of parallel actinolite needles,
with some chlorite and titanite and a
little plagioclase. The other is rich in
chlorite, plagioclase, and zoisite, and
contains titanite and a little epidote
and sericite. This schist is finely por-
phyritic, the phenocrysts being of
plagioclase (Fig. 12). Many have
been bent, sliced, or granulated by
the shearing. The white mica is
fairly well oriented and, together
Fic. 1r.—“Torn” plagioclase With the other minerals, is inclosed
phenocryst. The large dark area jn an irregular background or net-
in the middle of the photograph : L.
Fy ne Ms eee work of chlorite. There are some
crystal, the other two-thirds being chlorite aggregates which look as if
below the picture. The irregular they had formed from a mineral that
ee Pane ae SS as once present as phenocrysts. No
quartz is recognizable in either rock.
With reference to the origin of
these rocks, it would seem as if
their source was most probably igne-
ous. Some of them might have been
derived from sedimentary products of
incomplete decomposition, but they
can hardly have come from normal
argillitic material.
Parker Hill white schist—The
whitish schist that contains the dark
phyllitic fragments is composed prin-
Fic. 12.—Section of a pebble of
* j fine porphyry schist from the
cipally of quartz and orthoclase in “schoolhouse conglomerate” at
nearly equal proportions, somewhat the Black Mountain locality.
less plagioclase, and some chlorite and Balad tO) tr:
sericite. The particles of quartz and feldspar have every gradation
in size from the largest to the smallest (Fig. 13). There is relatively
little matrix, the larger grains being so numerous that they nearly,
76 FREDERIC H. LAHEE
&»
if they do not quite, touch one another. Many of the grains are an-
gular; none is conspicuously rounded, and they do not seem to have
been rounded before metamorphism. Of the two minerals, sericite
and chlorite, the latter is most plentiful. The chlorite is least likely
Fic. 13.—Section of a typical Fic. 14.—Section of a por-
psammitic member of the Lyman phyritic pebble of the ‘Parker
series. Enlarged r2 diameters. Hill dark schist.’’ Enlarged 15
diameters.
to have parallel orientation. Another specimen from farther north-
east near this horizon exhibited similar characters in thin section.
Parker Hill dark
schist.—The specimen
from which the sec-
tion was cut was ob-
tained northeast of
Parker Hill along the
strike of the rock ex-
posed in the Lisbon-
Lyman road, and it is
thought to belong to
the same horizon Fig. 15.—Part of the “egg conglomerate’? where
the majority of the pebbles are angular and subangular.
Che phyllite is a small Photograph by R. W. Sayles.
angular fragment ina
whitish clastic matrix of the kind just described. It is porphyritic
(Fig. 14), having small phenocrysts (o.13-1.0 mm.) of plagioclase,
often with well-preserved crystal form, distributed in a very fine
groundmass of plagioclase and chlorite. The phenocrysts do not
THE LYMAN SCHISTS OF NEW HAMPSHIRE ea
contain inclusions of the groundmass. This rock is remarkably
like a pebble taken from a conglomerate which Hitchcock’ called
the “egg conglomerate” (see Fig. 15), a pebble which would be
called a felsitic rock without hesitation.
GENERAL CONCLUSIONS ON THE ORIGIN OF THE LYMAN SCHISTS
Among the characters described in the foregoing paragraphs
many are of such a nature as to suggest that at least some members
of the Lyman schist group are igneous rocks—probably volcanic—
more or less modified by dynamic metamorphism. For the sake
of clearness and emphasis, the significant facts which lead to this
conclusion are reviewed below in summary form for three typical
rocks.
Porphyry schist of the Young’s Pond locality.—The quartz-
plagioclase porphyry schist which has been described from the
Young’s Pond locality is assumed to have been an effusive rock
for the following reasons:
t. It has a strong resemblance to the quartz porphyry type of
igneous rock. ;
2. It is massive, without bedding.
3. Locally it has faint indications of flow structure.
4. The phenocrysts are rather uniformly distributed through
the groundmass.
5. The quartz phenocrysts have high luster and high trans-
parency, a faint bluish opalescence, and a tendency toward
cleavage, all these being features not uncommon in true quartz
porphyries.
6. Some of the feldspar phenocrysts have crystal form.
7. There is a great difference between the sizé of the smaller
phenocrysts and that of the larger groundmass particles.
8. Many. quartz phenocrysts and some feldspar phenocrysts
contain embayments of the groundmass, these embayments having
1 C. H. Hitchcock, Geology of New Hampshire (1877), I, 333. This “egg con
glomerate” is exposed on the northwest slope of Blueberry Mountain and may grade
laterally into the Fitch Hill arkose. Most of its pebbles are of quartz porphyry,
quartz keratophyre, granophyre, devitrified rhyolite, and other felsitic types. The
great preponderance of effusive rocks among the pebbles is to be noted for comparison
with the Lyman series.
378 FREDERIC H. LAHEE
regular curving edges evidently due to magmatic corrosion and not
to subsequent localized granulation or recrystallization.
g. Some feldspar phenocrysts have zonal structure parallel to
the outlines of the corrosion inserts of the groundmass (Fig. 10).
1o. Both quartz and feldspar phenocrysts, and even those
feldspar crystals which have zonal structure, are quite free from
the type of inclusion of the groundmass which is so common in
many metacrysts.
11. Although two or three feldspar crystals are sometimes
attached as if they had grown so (Fig. 16), quartz and feldspar
never occur thus together. If the materials of
the schist were derived from the breaking up
} of a granitoid rock, small pebbles composed of
both quartz and feldspar would be expected.
Fee cena 12. All, or nearly all, of the feldspar pheno-
attached plagioclase crysts are albite. A clastic rock would be likely
individuals which to contain several species of fragmental feldspar,
a: Sane for there are plenty of rocks in this region which
diameters, ~~~-—«zave orthoclase, microcline, microperthite, micro-
pegmatite, etc., among their constituents.
13. The abundance of albite in this rock suggests that the
content of Na may be abnormally high for an argillitic sediment.
However, I have not analyzed the rock chemically, and the Rosiwal
method would be unsatisfactory on account of the difficulty of
determining the particles of the groundmass.
14. The preponderance of easily recognized pebbles of felsitic
rocks in the “egg conglomerate”’ proves that acidic effusive rocks
may be expected in the region.
If, then, we grant that the quartz-plagioclase porphyry schist
is effusive, its composition places it in the class of quartz kera-
tophyres, and the similar quartzless rock of Mormon Hill belongs
to the keratophyres. :
Parker Hill white schist—This is taken as representative of the
“tuff-like schists’? of the Lyman group. It is undoubtedly a
metamorphosed clastic as is demonstrated by the following facts:
t. Megascopically and microscopically it has a distinctly frag-
mental aspect.
os ne
ve
THE LYMAN SCHISTS OF NEW HAMPSHIRE 379
2. Locally it contains angular blocks and sometimes isolated
pebbles. ;
3. It grades into the fine variety of Lyman conglomerate schist.
4. It has obscure bedding (layers differing in texture) in some
places. :
5. There are all gradations in size between its largest and small-
est particles.
6. There is a relatively small proportion of small grains as
compared with the porphyry schist.
This Parker Hill white schist certainly was never a normal
clastic in the ordinary sense of the term. It might be called an
arkose schist on account of its having abundant clastic feldspar.
However, its more or less intimate association with effusive rocks,
the presence in it of the constitutents of the porphyry schists, both
as small particles (quartz and albite grains, etc.) and as larger
fragments (some whitish like the Lyman schists and some dark
like the Parker Hill dark schist), and the observed gradations
between it and the fine Lyman conglomerate schist which is com-
posed chiefly of sheared pebbles of felsitic nature—these facts
induce me to classify the rock as a metamorphosed tuff.
Conglomerate schist of the YVoung’s Pond locality.—There is no
doubt that this “‘schoolhouse conglomerate”’ looks very much like
a glacial deposit, as stated by Hitchcock’ and recently by Sayles;
but if the accepted criteria for till ever did exist here, they have
been entirely destroyed by metamorphism. For this reason it is
futile to look for signs of glacial abrasion on an underlying rock
pavement. ‘The weakness of the evidence for glacial origin was
fully appreciated by Mr. Sayles, and I may add,that evidence
against such glacial origin is almost, if not quite, as inconclusive.
However, one should bear in mind that great variation in size of *
constituent fragments and absence of bedding are characters shared
by talus, landslide débris, pyroclastic materials, and not infre-
quently even by river-laid alluvial cone deposits. Is it not more
probable that the “‘schoolhouse conglomerate,” being closely asso-
ciated with an effusive rock (quartz-plagioclase porphyry schist),
« C. H. Hitchcock, ‘‘ New Studies in the Ammonoosuc District of New Hampshire,”
Bull. Geol. Soc. Am., XV (1904), 472, and Geology of New Hampshire (1877), Il, 302.
380 FREDERIC H. LAHEE
having a large proportion of its pebbles and bowlders consisting
of effusive rocks, and having a paste which resembles the Parker
Hill white schist (cf. above), is a coarse pyroclastic, an agglomer-
ate, rather than a tillite ?
It is important to note that both Hitchcock and Hawes! main-
tained that rocks of the Lyman group were the outcome of the
metamorphism of sediments. Neither of these geologists held
the view that these schists were of volcanic origin, yet both were
struck by the resemblance between some members of the series
and ordinary felsite.
STRUCTURAL RELATIONS OF THE LYMAN SERIES
The structural relations, and therefore the age, of the Lyman
schists still remain obscure. These rocks are surely not younger
than Devonian, and they may be older, as has been stated by
Hitchcock. In several places on the Parker Hill-Mormon Hill
range stratigraphic structures point to an anticlinal axis eastward.
If this is so, since the Blueberry Mountain—Bald Hill range is
regarded as synclinal, the intervening valley is anticlinal. Again,
if this is so, it becomes necessary to explain the lack of correlation
between the Lyman schists on the western range and the marine
argillites and sandstones of the eastern range. Unconformity or
extensive faulting may be the cause. At present I do not feel
justified in discussing this subject further. More time should be
given to field investigation. The region offers ample opportunity
for research in petrology and in structural geology.
ACIDIC EFFUSIVE ROCKS EAST OF THE APPALACHIAN PROTANIS
South of the latitude of New York City the Appalachian
Mountains are flanked on the east by the Piedmont Plateau.
North of the same latitude, the New England Province corresponds
to the Plateau. Both regions are underlain by plutonic rocks and
folded, sheared, sedimentary rocks, chiefly of Paleozoic and pre-
Cambrian age. With extended study of these complex rocks two
results stand out conspicuously: an increasing number of meta-
*C. H. Hitchcock, Bull. Geol. Soc. Am., XV (1904), 468, 469; and G. W.
Hawes, “Mineralogy and Lithology of New Hampshire,” p. 176, in Hitchcock’s
Geology of New Hampshire, III (1878).
THE LYMAN SCHISTS OF NEW HAMPSHIRE 381
morphosed rocks is being transferred from the pre-Cambrain to
the Paleozoic, and the origin of the schists is found to be more
diverse than was at first conceded. It is in line with these results
that the variety and distribution of effusive rocks, both flows and
pyroclastics, interbedded with the schistose Paleozoic sediments;
are being expanded as investigation proceeds. In a paper written
in. 1894, G. H. Williams called attention to this fact.1 He briefly
described the following localities in eastern North America, where
volcanic rocks were known at that time: Newfoundland, Nova
Scotia, New Brunswick, that part of the province of Quebec lying
west of Maine and north of Vermont and New Hampshire, Maine,
Massachusetts, Pennsylvania, Maryland, Virginia, and the Caro-
linas. To this list it is probable that Rhode Island and New
Hampshire may now be added. Williams mentioned New Hamp-
shire in his text, but did not show any volcanic rocks in this state
on his map. He observed that ‘in New Hampshire felsites and
quartz-porphyries abound. They were regarded as eruptive by
Hitchcock and by Hawes when they occur in dykes, although the
latter regarded many of them, especially when interstratified, as
sediments fused in situ.’ This paper by Williams contains numer-
ous references. A list of more recent articles on the subject is given
by J. E. Pogue, Jr., in his “Geology and Structure of the Ancient
Volcanic Rocks of Davidson County, North Carolina.’’s
« “T)istribution of Ancient Volcanic Rocks along the Eastern Border of North
America,” Jour. Geol., II (1894), 1-31.
ZO Dp cits, Dp» 24:
3 Am. Jour. Sci. (4), XXVIII (1909), 218-38.
NOTES ON THE DISINTEGRATION OF GRANITE
IN EGYPT:
DONALD C. BARTON
Washington University, St. Louis, Missouri
INTRODUCTION
THREE PERIODS OF DISINTEGRATION IN THE ASWAN DISTRICT
THe RATE OF THE DISINTEGRATION OF THE GRANITE
At Aswan
At Luxor and Gizeh
THE CAUSES OF THE DISINTEGRATION
The Conventional Explanation
Inadequacy of This Explanation in the Case of the Disintegration in
Egypt
Moisture and the Disintegration
Agreement of the Observations in Egypt with Those Made in Europe
and in the Eastern United States
INTRODUCTION
The disintegration of the granite in Egypt has been treated
in a general way by Walther in his discussions of disintegration
in desert regions. It has been commented on by Ball and others.
The disintegration of the New York obelisk, composed of the
Syene red granite, has been reported upon by Julien. The follow-
ing notes were made by the writer in a recent trip to Egypt in
which especial attention was paid to the disintegration manifested
by the granite in the ancient quarries and ledges of the Aswan
district and in the temples and monuments of Upper and Lower
Egypt.
THREE PERIODS OF DISINTEGRATION IN THE ASWAN DISTRICT
The disintegration in the Aswan district seems to belong to two
periods other than the present. The products of what seem to be
the earliest period of disintegration are found at the contact of
« This paper is the result of work done as Sheldon Traveling Fellow, Harvard
University.
382
THE DISINTEGRATION OF GRANITE IN EGYPT 383
coarse. Syene red granite with the base of the overlying Nubian
sandstone (Cretaceous) (Fig. 1): They form a zone of what Ball
designates as “‘broken-down granite, a kaolinic mass with quartz
grains.” The zone is 1 to 13 m. in thickness, has a relatively
sharp even contact with the overlying sandstone and conglomerate,
but below grades through less and less disintegrated granite into
comparatively unaltered rock. The upper part of the zone is
composed of material that has suffered slight rearrangement, but
the middle and lower portions consist of the untransported débris
of disintegration. The feldspar of the upper portion is almost
completely kaolinized.. In the middle portion, the kaolinization
i! GH NA
Fic. 1.—Diagrammatic section across the region of the Aswan Cataract. 1, Dis-
integrated and decomposed zone at the base of the Nubian Sandstone. 2, The massive
granular disintegration. 3, Disintegration of the present.
is much less and in the lower portion it is not megascopically
noticeable. Although the disintegration was seemingly not of the
exfoliation type,’ it nevertheless took place roughly parallel to the
very level upper surface of the granite. The surface is so level as to
suggest a peneplain surface. The disintegration would seem to have
taken place contemporaneously with or immediately preceding the
deposition of the Nubian sandstone, and the kaolinization may
t According to the present use of the term, it is possible to distinguish several
types of disintegration. The term is applied in some cases to the breaking up of a
rock-mass into blocks and in other cases to the breaking up of a rock-mass through
the loss of cohesion between the constituent grains. The former process may be
termed ‘‘block-disintegration” and the latter, “‘granular-disintegration.”’ Allied
to the block disintegration is what may be termed the ‘‘exfoliation”’ type of dis-
integration in which thin plates of rock rift off parallel to the surface of a ledge or
block. The process seems to involve considerable loss of cohesion between the grains
and readily goes over into granular disintegration. The term disintegration is also
used in a loose sense to denote the chemical breaking up of the rock-mass. But as
Merrill advises, it would seem better exclusively to use for that process the term
““decomposition”’ and to reserve the term “disintegration” for the process of mechan-
ical breaking up.
384 DONALD C. BARTON
have taken place under the estuarine or marine conditions then
prevailing or at some later time under the action of ground-water.
The disintegration and decomposition penetrate cracks to the
depths of ro to 20 ft. and in one or two places may be seen to have
taken place before the disintegration next to be mentioned.
~ The effects of the second period of disintegration are mani-
fested in a tendency toward deep, granular disintegration massively
affecting the coarse Syene red granite at a level which is approxi-
mately that of the Aswan Reservoir when full. This disintegration
is best seen on the island of El Hesa, in some recently excavated
graves at the site of the former village of Garba. The graves are
cut back into hill slopes of various inclination and have a hori-
zontal depth of about 3 meters on the average and a height of about
1; m. The roof at the back commonly has a thickness of 1 to 2m.
The greatest distance to which a grave was seen to extend hori-
zontally backward from the surface of the hill slope was 4 m.
The height of the grave was about 13 m. and the roof at the back
was slightly over 2 m. in thickness. The graves are cut entirely
in the disintegrated, or rather, partially disintegrated, granite
and in no case were they seen to penetrate unaffected rock. The
disintegration has therefore penetrated to a depth of at least 3 to 4
meters from the surface. The disintegration is of the granular
type and, although affecting the rock uniformly, is not quite com-
plete; blocks of the granite may be obtained which to the eye
seem entirely sound but which crumble readily under the hammer.
In the shallow sections that are afforded there is not any appreci-
able decrease of intensity of the disintegration with depth. The
disintegration has been accompanied by slight but megascopically
noticeable kaolinization and in its products resembles closely the
partial granular disintegration which is found at a depth of about
4m. in the Morvan and Plateau Central regions of Central France.
This tendency toward massive granular disintegration is mani-
fested also at several points along the old Nile Valley about 1 km.
north-northeast of Shellal, at several points along the river trail
from Shellal to the Aswan Dam, at several points immediately
north of the village of Kuror along the river trail to Aswan, and
about one-half mile northeast of Kuror in a small pass on the trail
THE DISINTEGRATION OF GRANITE IN EGYPT 385
to Aswan. The disintegration in each of the cases is approximately
at the elevation of that on El Hesa. It is a distinctly noticeable
fact that in many of these cases, as for instance in the case of the
grave on El Hesa cut 4 m. back into a northerly facing 40° slope
lying at the foot of a cliff about 25 m. high, the disintegration has
penetrated to a depth of at least 3 to 4 m. in spite of the fact that
direct isolation is received only during the summer and then only
at a low angle.
Disintegration taking place under the present conditions is
abundantly shown by most of the exposed ledges and loose blocks
of the region and is manifested in three ways: (1) Surfaces which
have been exposed for a relatively short while show a slight rough-
ening. Individual grains and fragments of feldspar and of quartz
become loosened and are removed. (2) Surfaces which have been
exposed for a longer time show in addition exfoliation of thin
superficial layers commonly of about two-thirds of a centimeter in
thickness. Cross-sections afforded by broken blocks show that
megascopically noticeable incipient exfoliation has penetrated to
a depth of 10 to 15 cm. from the surface. (3) Disintegration takes
place also by the spalling and splitting of large blocks and frag-
ments, but the amount of disintegration taking place in this
manner in the Aswan region is not very great. Of these three
methods of disintegration that by exfoliation is by far the more
important. In the excavation for the dam and navigation canal,
concentric disintegration and decomposition were found to have
penetrated to a depth of several meters below the high Nile
level and are probably to be considered as going on at the
present.
The chief granite of the Aswan region is the famous Syene red
granite, a coarse red porphyritic granite composed chiefly of large
phenocrysts of orthoclase. Where the joints are comparatively
far apart, its outcrops under the effect of the concentric exfoliation
of the joint blocks resemble huge piles of bowlders. Where the
jointing is more pronounced and the joint blocks of much smaller
size, the concentric exfoliation is much less in evidence and the
outcrops are composed of, and surrounded by, detrital masses of
angular and subangular blocks and in appearance are very similar
386 DONALD C. BARTON
to the outcrop and surrounding detrital slopes of similar types of
rocks in New England.
The fine-grained granite of the region, somewhat similar in
composition to the coarse red granite, although with a lower
content of colored silicates, is not so severely affected by the dis-
integration. Exfoliation takes place very slowly, and although
the edges and corners of exposed blocks have in most cases been
rounded, the general form of the blocks is angular. The outcrops
in general aspect are not unlike these of the -more jointed phases
of the coarse red granite. The fine-grained granite is, however,
itself much jointed. It was not seen massively disintegrated and
small dikes cutting the massively disintegrated coarse granite
showed merely slight exfoliation of the edges and corners of the
joint blocks into which the dike is broken. Flaking and the loosen-
ing of single grains on exposed surfaces do not seem severely to
affect the fine-grained granite.
THE RATE OF THE DISINTEGRATION OF THE GRANITE
The rate of disintegration of exposed surfaces of granite at
Aswan is not as rapid as at first might seem. Many of the numer-
ous hieroglyphic inscriptions of this region show noticeable disin-
tegration and on this account relatively rapid rates of disintegration
have been postulated. These inscriptions almost without excep-
tion are carved on bowlders of exfoliation, and in but few cases
was there seemingly much effort on the part of the ancient Egyp-
tians to remove more than the most readily detachable plates of
exfoliation. The greater number of the inscriptions therefore
were carved on surfaces that were already partially disintegrated.
In the few cases in which the writer was able to satisfy himself that
the inscriptions had been cut in surfaces dressed back into fresh
rock, there was no disintegration noticeable and the inscriptions
were entirely fresh and sharp. Such inscriptions can be seen on one
of the two natural obelisks on the island of El] Hesa. The inscrip-
tions date from the reigns of Mentuhotep I, about 2100 B.c.;
Thutmoses IV, 1420-1411 B.c.; Amenhotep III, 1411-1395 B.c.;
and Psammeticus II, 588-583 B.c. The inscriptions show no
noticeable disintegration, and tapping with the finger or hammer
THE DISINTEGRATION OF GRANITE IN EGYPT 387
does not reveal the presence of incipient exfoliation or flaking.
The exposure is southerly and therefore one that affords the maxi-
mum exposure to insolation. These rocks, as can be seen from
Fig. 2, rise directly out of the Nile and there would seem to have
been no chance of their having been buried and protected by accu-
mulations of sand or débris. Other examples of inscriptions
carved in fresh surfaces and not showing disintegration are those
Fic. 2.—The Island of Konosso. View taken looking north-northeast. : The
hieroglyphics mentioned are on the south face of the right hand of the two natural
monoliths.
along the trail from Aswan to Shellal numbered by Weigall 323,
320, 334, 343, and 350 and dating from the eleventh, twelfth, and
thirteenth dynasties; an obelisk and a statue lying unfinished in
the ancient quarries and referred by Wiegall to the reign of Amen-
hotep III, 1411-1375 B.c., and numerous discarded quarry blocks
in the ancient quarries and along the ancient quarry roads, dating
probably from not later than the last century B.c. These blocks
in many cases consist of a half, a quarter, or an eighth of a bowlder
of exfoliation and in most cases it is readily possible to determine
which were the originally fresh and which were the originally exfo-
liating surfaces. The surfaces which were originally fresh are still
388 DONALD C. BARTON
fresh and show merely an infinitesimally thin film of tarnish and
alteration. Tapping revealed no incipient exfoliation. In micro-
scopic thin sections taken at right angles to the surface of a block,
the orthoclase is seen to be comparatively fresh; the oligoclase is
much clouded by decomposition products, but the alteration is not
sufficient to obscure the specific determination of the feldspar.
The ferro-magnesian minerals show slight decomposition and in
one of the sections there is considerable limonitic staining. The
degree of decomposition is no greater than -that which is very
commonly observed in sections of granite and is no greater toward
the surface than deeper in. There is no tendency, as far as could
be seen, toward incipient rifting parallel to the surface. The
sections were taken at right angles to surfaces which had a southerly
exposure and which were therefore exposed to the maximum heating
effects of the insolation.
Farther north in Egypt the rate of disintegration is more rapid.
At Luxor, Thebes, Gizeh, and in the museum at Cairo, the granite
(chiefly the coarse Syene granite) of statues, of obelisks, of por-
tions of the temples, and of the facing of the pyramids, shows in
the greater number of cases noticeable disintegration. That
manifested by the statues is manifested chiefly as exfoliation of a
thin film, o.5-o.7 cm. in thickness, from the pedestal, feet, and
lower portion of the legs. Above the knees, the original high polish
is commonly still intact, and tapping does not reveal incipient
exfoliation or flaking. Examples of this type of disintegration
can be seen on many, but not all, of the statues of Rameses II in
the Forecourt of the Temple of Luxor and by the statue of Rameses
II at the north entrance, by the colossal statue of Rameses II at
the entrance to the great Hypostyle Hall, Karnak (Fig. 3), and
by the medium-sized statue in the temple of Ptah, and by about
half the statues of the coarse red Syene granite and also those
of dark medium-grained rock possibly diorite in the museum at
Cairo. The statue in the Temple of Ptah is situated in a small dark
sanctuary and is not directly exposed to insolation. The other
statues at Luxor and Karnak are less well protected, but neverthe-
less are only very poorly exposed to the temperature changes con-
sequent upon solar heating. In the Great Temple of Karnak,
THE DISINTEGRATION OF GRANITE IN EGYPT 389
disintegration manifests itself as the spalling of the corners of the
uprights; as the exfoliation to the depth of about 1 cm. of the walls
in the Granite Sanctuary, erected in 313 B.c. by Phillip Arrhidaeus;
and as spalling and exfoliation of the lower 6 to 8 ft. of the fluted
columns in front of the Sanctuary, and also of the obelisk of Queen
Hatshepsut, 1591-1447 B.c. The obelisk of Thotmes I, now lying
in pieces on the ground, shows scattered, patchy flaking and under
tapping much incipient exfoliation is revealed. At the Temple of
Fic. 3.—Statue of Rameses II. Entrance to the Great Hypostyle Hall, Karnak,
showing in a characteristic manner the exfoliation of the pedestal, feet, and lower legs.
Medinet Habu, Thebes, disintegration is shown by the granite
pillars of the doorway both on the sides which are exposed to the
sun and on those which are not. In the Serapeum at Sakkara,
on the other hand, the surfaces of the huge sarcophagi, which are
hewn out of the coarse Syene red granite, still retain the high per-
fection of their original polish and show not the faintest trace of
incipient disintegration or exfoliation. The sarcophagi, however,
are in dry underground chambers whose temperature, according
to Baedecker, remains very constantly at about 80° F.
At Gizeh, the granite blocks which formed a part of the facing
of the second and third pyramids show for the most part on their
390 DONALD C. BARTON
exposed surfaces a very marked exfoliation to the depth of 0.5 to
o.8 cm. Minor exfoliation, in addition, is found along the joints
between the blocks. Exposed surfaces not exfoliating commonly
show marked granular flaking. The orientation of the surface, with ~
north, east, south, or west exposure, does not seem appreciably to
affect the intensity of the disintegration and exfoliation. Disinte-
gration and exfoliation are shown also by the granite facing that
extends for 30 ft. down the shaft on the north side of the second
pyramid, by the granite pavement of the temple at the east base
of the second pyramid, and by the granite blocks immediately to
the north of the east entrance to the temple. A striking feature
Fic. 4.—Diagrammatic sketch showing the greater degree of disintegration
below the old soil line than above. East entrance to the temple of the second
pyramid, Gizeh.
in this latter case, as can be seen from the accompanying sketch
(Fig. 4), is that the disintegration is distinctly stronger below what
seems to have been an old soil line than above it. A similar case
was noted at one of the pyramids at Sakkara. The débris resulting
from the disintegration and exfoliation in all these shows slight
but megascopically noticeable decomposition. The degree of the
alteration of the colored silicates is greater than that of the feld-
spars, and that of the plagioclase is greater than that of the ortho-
clase.
The pyramids of Gizeh date from the Fourth Dynasty, about
2850-2700 B.c., the statues of Rameses II at Karnak and Luxor
date from the Nineteenth Dynasty, 1292-1225 B.c., and the Granite
Sanctuary, Karnak, dates from the reign of Phillip Arrhidaeus,
318 B.c. The average rate of disintegration and exfoliation would
therefore seem to be about 1 cm. to 0.5 cm. in five thousand years.
THE DISENTEGRATION OF GRANITE IN EGYPT 391
The maximum rate, shown by the Granite Sanctuary, would seem
to be about 1 cm. in two thousand years, and the minimum rate
_would seem to be so low that the effects are not apparent in three
thousand years. In addition to this variation in the-rate of dis-
integration apparently corresponding to a variation in the conditions
to which the granite is exposed, there is apparently also a variation
depending upon the orientation of the disintegrating surface in
reference to certain directions within the rock, possibly the rift and
the grain, or possibly a faint schistosity which is almost universally
present in the Syene granite.
THE CAUSES OF THE DISINTEGRATION
The conventional explanation of disintegration in a region of
desert climate like that of Egypt is that the disintegration results
_ from the racking to pieces of the rock through the contraction and
expansion consequent in the high-temperature ranges. In the
case of Egypt, there would, however, seem to be serious objections
to this explanation, although some disintegration undoubtedly
does take place in that manner. The first objection is that,
although the temperature range is of the same magnitude at both
Aswan and at the pyramids of Gizeh, the rate of exfoliation is very
much less at the former place than at the latter, and furthermore,
that, although the statues in the temples are exposed in many cases
only to very low temperature ranges, the rate of exfoliation in
many of these cases is of the same magnitude as that at the pyramids
of Gizeh. The second objection is that the massive granular dis-
integration of the Aswan region penetrates to a greater depth than
appreciable temperature changes can be expected to extend. The
depth of the zone of warming at midday in desert regions is given
by Walther as the result of many observations as only about 19 cm.
The annual temperature variation is said by Sir William Thompson .
to be reduced at a depth of 8 m. (25 ft.) to one-twentieth of its
superficial amount. The mean annual temperature range in
Egypt is less than 20° C and, at the depths to which disintegration
can be seen to have penetrated at Aswan, 3 to 4 meters, must be
reduced to amounts which are essentially negligible, especially
since the period of the range is so long. The mean monthly range
392 DONALD C. BARTON
is only 24°C. and at those depths must be even more seriously
reduced in amount. The diurnal temperature range, furthermore,
should be entirely absent at those depths, especially on slopes such
as those in which many of the graves on El Hesa are cut, where
direct insolation is received only during the summer and then at
a low angle. Granite itself has a low coefficient of conductivity
and that of dry granitic sand must be much lower; it would there-
fore not seem surprising that a blanket of several feet of disinte-
grated granite is found to be an effective insulating agent for the
fresh rock beneath.
At Aswan and at the pyramids of Gizeh, the only factor by
which the conditions of exposure of the exfoliating rock differ is
in the humidity. At Aswan there is no rainfall, there is only a light
dewfall at night, and the relative humidity at 8:00-9:00 A.M. varies
from 28 to 58, average 39; while at the pyramids of Gizeh there
are several light showers,each year, there is a moderately heavy
dewfall at night, and the relative humidity at 8:00-9:00 A.M. runs
from 64 to 87, average 72.
In the case of the exfoliating statues, their sheltered positions
in the temples and the connection between the exfoliation and the
lower portions of the statues would seem to indicate that the cause
of the exfoliation lay not so much in the temperature changes as
in some factor connected with the ground, as for instance, in the
ground-water or moisture, and it is to such a cause that the exfoli-
ation is ascribed by G. Daressy of the Department of Antiquities,
Egypt, who says: “Les granites exposés continuellment a leau
ou au soleil se conservent bien, mais ot ils se degradent, c’est
lorsqu’ils ont été enfouis dans un sol humide. La formation de
sels nitrate et autre fait alors decomposer le granite, sirtout lorsque
le terrain est alternatement sec et humide.” The expansion con-
sequent upon the kaolinization of the feldspar is emphasized by
Merrill as the cause of the disintegration of the granite near
Washington, D.C. Although kaolinization is megascopically very
noticeable in these cases, it would scarcely seem to be of sufficient
amount alone to account for the observed disintegration and
exfoliation.
THE DISINTEGRATION OF GRANITE IN EGYPT 393
The massive granular disintegration of the Aswan region
possibly also may be attributed directly or indirectly to the effect
of moisture. The disintegration is found at and for some few
meters below the level at which the Nile must have flowed when
in the old Nile Valley between Aswan and Shellal. At that time
the granite at the level of this disintegration must have been
alternately above and below the ground-water level, as the Nile
rose and fell, and must consequently have been alternately wet
and dry. At the present level of the Nile, the granite was found
in the excavations for the navigation canal and for the dam founda-
tions to be almost completely disintegrated and decomposed to a
depth of several meters below the level of the high Nile. Decom-
position in this case has, however, rather predominated over simple
disintegration.
These observations in the light which they throw on the cause
of the disintegration of granite are in agreement with similar
observations which the writer made in the Odenwald, in the Vosges ©
Mountains, in the Norvan and Auvergne districts of France, and
in the eastern United States. In the many places in which the
disintegration has reached the depth of 20, 30, or even 4o ft., it
seems impossible to believe that the temperature changes are of
sufficient amount to be of any appreciable effect. Diurnal, weekly,
and monthly temperature changes must be completely eliminated
at those depths, and according to Sir William Thompson the
annual temperature range is reduced at a depth of 25 ft. to one-
twentieth of its superficial amount. The disintegration in these
places is accompanied in many cases by very much more and in
other cases by only slightly more decomposition than is the dis-
integration in Egypt.
A RECORDING MICROMETER FOR GEOMETRICAL
ROCK ANALYSIS
S. J. SHAND
Victoria College, Stellenbosch, South Africa
The quantitative éstimation of minerals in rock sections is
generally recommended as a valuable exercise, but in practice it is
far too seldom performed. The reason is that the recognized
methods of estimation are very tedious, while the results, when
obtained, have not hitherto been put to any systematic use in the
classification of rocks. The usual methods are of two kinds, viz.,
(1) separations, either gravitational or magnetic, the separated
portions being weighed directly; and (2) geometrical methods,
involving measurement either of areas or of diameters, and sub-
sequent calculation of percentage volumes and percentage weights.
Of estimations of the latter class, the following variants are
known to me:
t. The method of Delesse: The surface of the rock is polished
and oiled, and the outlines of the grains are traced on transparent
paper, the areas corresponding to different minerals being distinc-
tively colored. The paper is then pasted upon tinfoil, and cut up
along the boundaries of the grains. The fragments having been
grouped according to color, the paper is removed and the tinfoil
weighed. The weights so found are proportional to the areas traced
upon the paper, hence also to the volumes occupied by the different
kinds of grains, provided that the rock is uniform throughout. To
get the proportions of the various minerals by weight, each volume
must be multiplied by the specific gravity of the corresponding
mineral.
2. The outlines of the grains may be traced upon squared
paper, and the areas obtained by counting the number of squares
occupied by each mineral, all broken squares being reckoned as
half-squares.
394
MICROMETER FOR GEOMETRICAL ROCK ANALYSIS — 395
3. Methods 1 and 2 can be applied to microscopic sections by
the aid of a camera lucida attached to the microscope. An ordinary
photographic camera can also be used, the outlines of the grains
being sketched from the enlarged image on the focusing screen.
4. Ifa dark room is at hand, it is sometimes preferable to photo-
graph a rock section instead of sketching it. The print can be
examined either by weighing or by means of squared paper.
5. A squared ocular micrometer, by means of which the areas
of the grains in a section can be measured directly under the
microscope, was tried by Rosiwal. It was found to be less advan-
tageous than the following method, viz.:
6. Rosiwal’s linear traversing method:" If the work be executed
with care and under all necessary precautions, this is the simplest
and perhaps for that reason the most accurate of all geometrical
methods of rock analysis. The measurement of areas is replaced
by the measurement of: diameters along a selected line or lines.
Either a microscopic section or the smooth face of a hand-specimen
of the rock may be employed, according to whether the rock is of
fine or coarse grain. In the latter case, a graduated rule or tape
is required; in the former, an ocular micrometer. Any kind of
micrometer will do, but the estimation is facilitated by the use
of certain special types, such as the “‘planimeter ocular” of Hirsch-
wald.? Subject to certain conditions, the number representing
the sum of the diameters of all grains of one kind is proportional
to the volume of the mineral concerned. .
So far as tediousness is concerned, all these methods are more
or less on the same level; the measurements are very wearisome
and take a long time to perform. Generally speaking, one would
expect weighing to be a more exact process than the use of squared
paper, but then the weighing must be preceded by sketching and
cutting out, and appreciable errors may creep in during these
manipulations; furthermore, one cannot be sure that the material
weighed, be it tinfoil, cardboard, or paper, is everywhere of the
same thickness. On the other hand, the counting of innumerable
« Rosiwal, ‘Uber geometrische Gesteinsanalysen,’ Verhandlungen der k.k. geolog.
Reichsanstalt, Wien (18098), No. 5.
2 J. Hirschwald, Centralblatt fiir Min., Geol., Pal. (1904), No. 20.
306 S. J. SHAND
tiny squares is a most aggravating business, and the fewer the
squares, the greater the probable error in the result. On the whole,
the advantage seems to be with the Rosiwal method, as being both
simpler and more direct than the others. The practical disad-
vantages of the method are two: First, the making of very many
minute measurements by the aid of the scarcely visible scratches
on the eyepiece micrometer puts a severe strain upon the eyesight,
as well as upon the patience, of the observer. After an hour or
two of such work I have sometimes been nearly blind. Secondly,
the writing down and adding up of some hundreds or even thousands
of measurements is itself a most tedious operation.
To obviate these serious disadvantages of the Rosiwal method,
I have devised a stage micrometer which both makes the measure-
ments and performs the addition of them; it consequently effects a
great reduction in the time needed for the estimation, and inci-
dentally reduces the strain on the eyes to a minimum. The first
instrument was made from my drawings by Mr. T. A. Linton, at
the South African College, Cape Town, and I have pleasure in
expressing my appreciation of his excellent workmanship.
The design is very simple, and will easily be followed with the
aid of the drawings (Figs. 1, 2, 3). The rock section, mounted as
usual on a glass slide, fits into a rectangular brass sledge A, which
is movable to right or left of the observer, within another sledge B,
the movement being accomplished, and its amount recorded, by
the micrometer screw L. Sledge B moves in the same manner and
direction within sledge C, the movement being performed and
recorded by the micrometer screw R. Sledge C has no transverse
movement; it carries two runners on its under surface which
travel in grooves on the sides of the rectangular stage of the micro-
scope; the only movement of this sledge is to and from the observer
and is effected simply by hand. .
Suppose it is required to estimate the volume of augite in a
dolerite. The section is put in place and adjusted till one edge
of it appears against the point of intersection of the cross-wires
in the eyepiece of the microscope. The readings of screws R and
L are written down. Then screw & is turned continuously until
a grain of augite is brought up to the cross (i.e., the point of inter-
MICROMETER FOR GEOMETRICAL ROCK ANALYSIS 397
S J SHAND.
|
1 mE
LARAANUUIUUUTL
Micro S)iide
! RG mimi mutans: ae
Fig. J
|
|
|
!
}
\
l
t
Working drawings of recording micrometer.
FIGS. I, 2, 3.
308 S. J. SHAND
section of the cross-wires); screw Z is now turned until the grain
travels past and its other margin lies exactly beneath the cross;
then screw X is turned till the next augite grain comes into position;
then screw Z till the grain has passed, and so on. When the
traverse has been completed, which with a section of ordinary size
may take from one to three minutes, the readings of the microm-
eter screws are again noted and written down below the former
readings. It is obvious that the difference between the two read-
ings of screw L gives the sum of the diameters of all the augite
grains which were intersected during the traverse, while the differ-
ence for screw RX gives the sum for all other minerals in the rock.
Without stopping to make these subtractions, however, sledge C
is pushed forward into a new position and a second traverse is
made in the return direction; at its completion the micrometers
are again read and the readings jotted down beneath the previous
ones. Sledge C is again. pushed forward, and another traverse
made, and so on until the number of traverses is considered sufhi-
cient. One may now proceed to the subtraction of the successive
readings, and the calculation of the percentage of augite, which is
obviously
sum of successive differences of L
sum of successive differences of L + sum of successive differences of R
2 TG0:
The most expeditious manner of recording the readings is to write
them down in parallel, vertical columns in the middle of the page;
then, when all the measurements have been made, the differences
of ZL are quickly filled in to the left and the differences of R to the
right, as in Table I, on p. 399, which is part of an actual
estimation.
It will be seen that by this method only two numbers have
to be recorded for each traverse after the first, while by any other
method some twenty or more may be necessary.
It may be advisable at this stage to recall the conditions which,
as Rosiwal has pointed out, must be observed if the linear traversing
method is to give reliable results.
1. The length measured must be at least one hundred times the
average grain of the rock. (With the additional facility afforded
by the recording micrometer, it would involve little extra labor
MICROMETER FOR GEOMETRICAL ROCK ANALYSIS 399
to increase this minimum to two hundred or even four hundred,
and I strongly advocate the increase.)
2. Two measured lines should be at least the width of a grain
apart.
3. When the constituents are fine-grained and uniformly
distributed, measurement of a single section may be sufficient; if
coarse-grained, several sections may be necessary in order to satisfy
conditions 1 and 2.
TABLE I
Diff L R Diff
| 3.82 8.05
6.43 16.60
I0.25 24.65
9.18 13.40
TOT EE GAG
5.86 17.45
6.93 28.70
6.93 16.25
0.00 12.45
7.62 15.23
7.62 27.68
36.02 78.93
oc 36.02 fie
Percentage = |-5 o> +7803 X100= 31.3
Total distance traversed, 57.5 mm.; time taken
for measurements and calculation, 12 minutes.
4. In the case of a rock with parallel structure it is necessary,
and in most cases it is desirable, to take measurements both along
and across the section.
5. The most accurate method is to measure all the minerals
present at the same time, rather than one at a time, although the
latter is the quicker way. (This recommendation applies to the
use of an ordinary micrometer; it is of course inapplicable to the
recording micrometer.)
6. In the case of coarse-grained rocks it is often quickest to
measure a polished face macroscopically, using sections only for
minor or microscopic constituents. |
Rosiwal’s practice is to draw fine lines on the cover-glass with
ink, and then measure along these lines. This is not necessary
400 S.J: SHAND
if the stage of the microscope happens to be ruled with cross-lines,
as is often the case.
The method having been described, it remains to add some
details about the construction of the instrument. In making the
first model, we took the micrometer screws out of two small spherom-
eters; these had just the right length (about 1} inches) and pitch
Fic. 4.—Photograph of original micrometer
(o.5 mm.) and were used almost without modification. The num-
bers on the graduated disk run in the correct direction for screw L,
but must be reversed for screw R. These screws proved, on trial, to
be unsatisfactory, having been taken from a cheap type of spherom-
eter (the only kind obtainable in South Africa at the time), and
better ones have since been substituted for them by Messrs. Swift
& Son, London. It is of course essential that the screws shall be
machine-cut with the highest degree of accuracy; that the axis
shall be perfectly straight; and the graduated disks truly plane
and set exactly at right angles to the axis. The precise pitch of the
MICROMETER FOR GEOMETRICAL ROCK ANALYSIS 401
screw does not matter at all, but a pitch of about one-half to one
millimeter is convenient. The scales which record the movement
of the screws are of course graduated to correspond to the pitch,
and the divisions on both scales are numbered from right to left.
Fic. 5.—The micrometer in position on the stage of an “ Allan Dick”’ petrological
microscope (Messrs. Swift & Son, London).
The ends of the screws may be rigidly attached to the sledges A
and B, but can be more simply secured by means of backlash springs.
The innermost sledge A carries two slots, one of them (abcd) made
to take the standard English size of slide (75X25 mm.), the other
402 S. J. SHAND
(efgh) to take German slides (48X28 mm.). Two small spring
clips (not shown in the figure) serve to prevent any slight movement
of the glass. In order to allow of measurements being made in
two perpendicular directions across a rock section, four short pins
are inserted in the sides of sledge A; these make it possible to fix
a German-sized slide in cross position upon the micrometer, but
the English slides are too long to permit this. .
The attachment of the outermost sledge C to the stage of the
microscope is effected by means of runners with beveled edges which
fit into grooves in the sides of the stage. One runner is fixed
directly to the under surface of the sledge, the other is attached by
a simple wire spring to a fixed cross-bar on the under surface of
the sledge. This simple arrangement could be replaced, if desired,
by a mechanical movement; in any case it would be an advantage
to have an additional screw (V, Figs. 1, 2) by means of which the
instrument could be clamped to the stage in any desired position.
My instrument was made to fit the stage of an ‘Allan Dick”
microscope (Swift & Son), but it is obviously adaptable to any
microscope with a rectangular stage. It could even be adapted
to a circular stage by means of a rectangular plate clamped
temporarily on top of the stage.
The instrument, as actually made for me, differs in some minor
points from the drawings. For instance, the micrometer screws
are not rigidly connected to the sledges A and B, as the drawing
suggests, but are attached by simple backlash springs which can
be seen in the photographs (Figs. 4, 5). The dimensions of the
side- and end-pieces of the sledges were slightly increased for the
sake of greater strength. The figures relating to these parts are as
follows:
Length of sledge A, 85 mm.
Width of sledge A (including bevel), 37 mm.
Travel of sledge A, 16 mm. (this might be increased).
Length of sledge B, 108 mm. (this might be increased).
Width of sledge (including bevel), 45 mm.
Travel of sledge B, 35 mm.
Length of sledge C, 127 mm.
Width of sledge C, 54 mm. (might be reduced to 52).
Thickness of material throughout, 3.5 mm.
MICROMETER FOR GEOMETRICAL ROCK ANALYSIS 403°
It would be well to allow a greater travel to sledge A by slightly
increasing the length of sledge B—say to 112 mm.
A well-finished instrument of this kind could not be made for
much less than £5, hence it is not likely to become part df every
-petrologist’s equipment; but in view of the saving of time and
eyesight which it effects the initial outlay is inconsiderable, and
the gain to descriptive petrography, if it should succeed in
popularizing the geometrical analysis of rocks, would be very
great.
The instrument has been examined by Messrs. J. Swift & Son,
London, who have all the information necessary for executing
copies of it.
EXPRESSION OF THE “COLOR RATIO” OF A ROCK
It has always appeared to me to be a matter of great importance
in rock descriptions to state the proportion of light to dark minerals
accurately. The terms “‘leucocratic” and “melanocratic’”’ have
proved extremely useful in giving a rough indication of this pro-
portion (which I am in the habit of calling the “color ratio” of
the rock), but something more is urgently required. Of course
the fundamental point of difference between the light and the
dark minerals does not lie in their color, but in their specific gravity,
to which, however, the color affords a convenient index, inasmuch
as all minerals of gravity less than 2.8 are leucocratic (predomi-
nantly light-colored) and those of higher gravity are melanocratic
(predominantly dark-colored). It is becoming more and more
apparent that differences of specific gravity must be reckoned
among the chief causes of magmatic differentiation, and for this
reason, as well as for its purely descriptive value, the color ratio
must receive quantitative recognition in the future.
With the micrometer described above, it is possible to measure
the color ratio of a fine-grained rock with a high degree of accuracy
in a period of ten to thirty minutes, according to circumstances.
Having ascertained the ratio, the next question is how best to
express it, and the way which does least violence to our accepted,
illogical system of nomenclature is to resort to a system of prefixes.
404 S. J. SHAND
The following ratio and the corresponding prefixes are simple and
expressive :
Light minerals more than er cent lo or L
8
“ “ “ “ go a“ 1 i
“ “ “ “ oO a9 ; or l
So ls {
“ “ “ “ 70 a lL \
: ‘ oe or
“ “ “ ‘ 60 le J
“ “ “ “ i
« « « oa « s | or lm
Dark 50 m; if
“ “ “ “ 60 a m6 \
« «“ «“ «“ 70 « m; f or m
“ “ “ “ So ac ms \
“ “ “ “ 90 iT; m J Or 7
= 9
“ “ “ “ 07 “ Myo or M
Examples: L=granite (alaskite); ls=syenite; Im=dolerite; m=syenite
(shonkinite); myo=pyroxenite, etc.
REVIEWS
Origin of the Bighorn Dolomite of Wyoming. By Exior BLAacK-
WELDER. Bull. Geol. Soc. Am., XXIV, 607-24, plates 8,
. December 22, 1913.
The Bighorn dolomite is widely distributed in northwestern Wyo-
ming. Its fossils, mostly corals and crinoid stems, are rare and seldom
well preserved, but indicate an Ordovician age, possibly including
Silurian also. Chemically the formation is a very pure, normal dolomite,
with very little terrigenous matter. Its weathered surface is character-
istically coarsely pitted and fretted, owing, not to intermingling of sili-
ceous with calcareous matter, but to compact fine-grained dolomite
structures imbedded in a matrix of more coarsely crystalline and porous
dolomite. The ill-defined branching patterns due to differential weather-
ing are probably of organic origin, more likely representing banks of
calcareous algae than plantlike animals. The obliteration of original
organic structures is assigned to the process of crystallization of the
dolomite, probably taking place almost simultaneously with deposi-
tion on the sea floor. The deposits were doubtless made in an epicon-
tinental sea less than 100-120 meters deep.
Re CaaVie
On Oceanic Deep-Sea Deposits of Central Borneo. By G. A. F.
MOoLeNGRAAFF. Koninklijke Akademie van Wetenschappen
te Amsterdam, Proceedings of the meeting Saturday, June 26,
1909. Pp. 7, map tr. .
The Danau formation, which outcrops over an area of approxi-
mately 40,000 sq. km. in central Borneo, consists of cherts and hornstones
formed almost entirely from the tests of Radiolaria. The char-
acter of the formation is very constant throughout the area. It consists
of two types: the one, a true Radiolite, is semitransparent, hard, and
brittle, with a color varying from milk-white to red or green, and is
composed almost exclusively of the closely packed tests of Radiolaria;
the other is an argillaceous chert, always red in color. The latter con-
tains fewer Radiolaria and is analogous to modern deep-sea red clay
deposits. The former corresponds to Radiolarian ooze. This large
405
400 REVIEWS
area of deep-sea deposits clearly indicates a very deep submergence of
this region, probably during the Jurassic period. The deposits probably
occur in geosynclines developed at the edge of the permanent Australa-
sian continental segment.
R. Ca Mie
Glaciology of the South Orkneys: Scottish National Antarctic Expedi-
tion. By J. H. Harvey Pirie. Trans. Roy. Soc. Edin.,
XLIX, Part IV, pp. 831-61. Figs. 14, pls. 11, including one
map.
The South Orkneys have such a climate that the line of perpetual
snow is practically at sea-level; the summer temperatures are rarely
above freezing-point. The mean annual temperature is 22°7 F. The
mean temperatures of the warmest and coldest months are 31°5 and
12°0 F., respectively. Foehn winds having passed over the central
highlands sometimes produce as high a temperature in midwinter as in
summertime.
The islands are almost entirely snow-covered throughout the year.
The resulting glaciers are characteristically antarctic in type. The
surfaces are practically all covered with névé, there are no surface
moraines, crevasses are rare except at escarpments, the whole mass of
the glaciers shows stratification, and the glaciers terminate in sea-cliffs.
The land: relief gives rise to various forms of glaciers:
I. Ice-sheets, including:
a) Inland ice.
b) Ice caps of the Norwegian type.
c) Much of the Spitzbergen type of ice caps. These are ice sheets which
conform to the topography, overlying both valley and hill.
II. Glaciers properly so called.
a) Valley glaciers.
b) Suspended cliff glaciers.
III. Piedmont glaciers.
These cover the low slopes between the mountain sides and the seashore.
They end in cliffs from 15 to 20 meters high; their surfaces are uniform
and snow-covered, having a gentle slope from the sea to the hills behind.
They are fed by local precipitation and are not dependent upon snow-field
reserves; they show well-marked horizontal stratification:
IV. Glaciers of the coastal belt and shelf.
a) Shelf-ice, such as the Great Ross Barrier.
b) Ice-foot glaciers which lie in the zone between land and sea. They
’ are composed of layers of névé ice formed in place chiefly of drift snow
supplied by wind action.
REVIEWS 407
The surface of the ice is undulatory, conforming to the surface of the
underlying ground. In one place the slope is opposite to the movement
of the ice. The glacier as a whole may be traveling uphill for several
hundred feet, but the total rise of the upper surface is thought not to
exceed 20 feet.
The glaciers are not notably advancing or retreating; in most places
cliff terminations at the shoreline indicate advance, but occasional
rounded ‘‘snout’’ endings bear witness to a slight retreat. The small
number of ice falls from the cliffs also disproves any notable advance.
Tn certain places the ice strata are slightly turned up at the glacier edges,
but there is no sudden upturning at the end; this conforms to the other
indications of but slight movement.
Englacial material is rare and consists chiefly of wind-dropped rock;
sand, pebbles, and bowlders are uncommon. In one place the ice
grains were seen to be drawn out and arranged in sweeping curved lines
which follow the direction of glacial flow. The pounding crystal faces
are usually not plane but curved.
From imperfect data collected on the speed of temperature waves
through the ice, it appears that a wave of about 5° change in temperature
_ penetrates 2 feet in about 2 days, and 4 feet in about 5 days.
The islands seem to be the serrated tops of a mountain range which
has been deeply dissected by glaciers while the islands stood at a mark-
edly higher elevation above the sea.
Hie 03),
The Upper Devonian Delia of the Appalachian Geosyncline. By
JosEPH BarRELL. In three parts. Am. Jour. Sci. [4th Ser.j,
XXXVI (November, 1913), 429-72; XXXVII (January,
1914), 87-109; XX XVII (March, 1914), 225-53, Figs. 5.
The Upper Devonian Oneonta and Catskill formations, that consist
of alternating red shales and gray sandstones, of the Appalachian geosyn-
cline in southeastern New York and northeastern Pennyslvania are
believed to be “‘subaerial delta deposits [of westward-flowing streams}
in a dry but not arid climate; a climate probably equable in temperature
but subject to seasonal rainfall.” The Oneonta is 1,000 feet thick in
the Catskill Mountains; the Catskill runs up into thousands of feet in
thickness. The Portage and Chemung formations are the shallow-sea
equivalents of the Oneonta and Catskill beds. The inland sea in which
the former were deposited bordered the subaerial delta on the west and
southwest. ‘The included map ‘“‘shows the shore line at the close of the
408 REVIEWS
Devonian farther west than any previous map but the margin of the
sediments farther east, except for the New Jersey strait of Schuchert
which is here eliminated.”” The Upper Devonian sediments are believed
to have extended northward beyond Lake Ontario and as far eastward
as the margin of the present coastal plain; their removal over a great
part of this area is referred to pre-Newark (Mid-Triassic), Jurassic, and
post-Jurassic (Comanche and Cretaceous) erosion epochs. These
Upper Devonian beds apparently formed a great piedmont plain that
stretched westward from Appalachia; the Skunnemunk conglomerate
(2,500 feet thick) is aremnant. This plain thickened from east to west
and in so doing changed from coarse to fine sediments. The indications
are that the drainage divide of Appalachia ‘“‘was at least as far east as
the present 100-fathom line southeast of Long Island and New Jersey.”
V- O28)
Geology and Ore Deposits of the Monarch and Tomichi Districts,
Colorado. By R. D. CRAwrorp. Bull. Colo. Geol. Surv.
No. 4, 1913. Pp. 317, pls. 15 (including 4 maps), figs. 15.
The Monarch district les in the southwestern part of Chaffee
County, Colorado, on the east slope of the Sawatch Range. The
Tomichi district, which is in Gunnison County, is on the west slope of the
range and joins the Monarch district on the west.
The sequence of formations is as follows: pre-Cambrian gneisses,
schists, granites, pegmatite, and quartzite; the probably Upper Cam-
brian Sawatch -quartzite (20+ feet); the mid-Ordovician Tomichi
limestone (400 feet); the Upper Devonian and early Mississippian
Ouray limestone (600-800 feet); the Pennsylvania Garfield formation
(2,800 feet); the Permo-Pennsylvanian (?) Kangaroo formation (about
3,000 feet); post-Carboniferous quartz monzonite, granular rocks,
porphyries, flow, and volcanic breccia; Pleistocene and later glacial
and fluvio-glacial deposits; recent deposits.
The Sawatch quartzite does not outcrop in the Monarch district.
In the Tomichi district, the Garfield formation is only a few hundred
feet thick, and the Kangaroo formation is wanting.
Unconformities exist between the following formations: the pre-
Cambrian and Sawatch, the Sawatch and Tomichi, the Ouray and
Garfield, the Garfield and Kangaroo, the Kangaroo and _ volcanic
breccia, the Pleistocene and older deposits. Regarding the interval
between the Tomichi and Ouray, the author notes that “although one
REVIEWS 409
or more stratigraphic breaks may be present, the beds show no angular
unconformity.” An unconformity is probable between the Devonian
and Mississippian portions of the Ouray.
Pronounced folding and faulting occurred in post-Kangaroo (Permo-
Pennsylvanian(?)) time.
The primary ore minerals of the Monarch and Tomichi districts are
believed to be genetically related to the quartz monzonite intrusion.
_The principal ores produced in the Monarch district are of lead, silver,
gold, copper, and zinc. They occur as replacements in limestone and
dolomite, filling of fault fissures in limestone and quartzite, fissure veins
in igneous rocks, contact deposits, and as deposits in pegmatite, gneisss,
and schist. Further development is encouraged.
The silver-lead ores now mined in the Tomichi district are chiefly
sulphide ores. The iron ore bodies are of magnetite and limonite. The
ores occur as replacements in limestone and dolomite, contact deposits,
fissure veins, and as bog iron deposits. The future of the district lies
in ‘the development of claims in groups.”
Detailed descriptions of the mines of both districts are given.
WeOe AR
Reconnaissance of the Geology of the Rabbit Ears Region, Routt,
Grand and Jackson Counties, Colorado. By F. F. Grout,
P. G. WorcesTER, and Juntus HENDERSON. Bull. Colo.
Geolj Surva No, 5, Part 1, 1913. Pp. 57, pl: 1:
The Rabbit Ears region includes about 212 square miles in Routt,
Grand, and Jackson counties, Colorado, ‘‘along and near the west end
of the Rabbit Ears Range.”’
The geological sequence is as follows: Archean gneisses, schists, and
granites; Permian or possibly Triassic ‘‘Red Beds”; the Upper Jurassic
or Lower Cretaceous Morrison formation; the Cretaceous Dakota(?),
Benton, Niobrara, and Pierre formations; early Eocene coal-bearing
beds; post-Eocene volcanic breccia, dikes, and sheets; Pleistocene and
Recent deposits.
Unconformities occur between the Archean and the “Red Beds,”
the ‘Red Beds” and the Morrison, probably between the Morrison and
the Dakota(?), the Pierre and the early Eocene coal-bearing beds, and
the coal-bearing beds and later deposits.
Folding “began at or just after the close of Cretaceous time, probably
2)
continuing for some time into the Tertiary. .... It is ‘‘probable
410 REVIEWS '
that igneous activity began in late Cretaceous or very early Eocene
time and continued till very recently, and that there were several quite
distinct periods.”
VOU
Permian of “ Permo-Carboniferous” of the Eastern Foothills of the
Rocky Mountains in Colorado. By R. M. Burrers. Bull.
Colo. Geol. Surv: No. 5, Part 2, pp. 6s-xor. Fig. 1-
This report is concerned with the determination of the age of the
Lykins formation, which was assigned by Fenneman to the upper part
of the ‘‘Red Beds”’ in the Front Range of eastern Colorado.
The Lykins formation, which varies considerably in thickness, con-
sists of red shales and shaly sandstones, with a few sandy or shaly
limestone beds. On the basis of the faunal evidence, the lower part
of the Lykins is placed in the Pennsylvanian and an intermediate zone
above is tentatively correlated with the Rico formation (Permian( ?))
of the San Juan region. ‘This leaves too-400 feet of shales to represent
the Permian or the remainder of the Permian, the Triassic, and all the
Jurassic up to the Morrison.”
V. Oise
The Geology of Central Ross-shire. By B. N. Peacu, L. W. HInx-
MAN, E. M. ANDERSON, J. Horne, C. B. Crampton, R. G.
CARRUTHERS. Petrological Notes by J. S. FLrerr. Memoirs
of the Geological Survey of Scotland, No. 82, 1913. Pp. 114,
pls. 8, figs. ro.
The western quarter of County Ross is cut off by the great Moine
thrust line. The Strathconan fault is the dominant one in the area
considered. It is of the type described as a “wrench fault.”” The direc-
tion of the fault line is a little east of north, and the lateral movement was
to the northeast on the east side, and to the southwest on the western
side. There are many Lewisian inliers thrust upon the younger Moine
series.
The Lewisian gneiss is a basement complex of various rocks of differ-
ent ages and includes altered sedimentary rocks that were denuded and
affected by contact metamorphism before the deposition of the Moine
sediments.
The Moine series comprises quartzose schists or quartz-biotite
granulites and garnetiferous mica-schists or pilitic gneiss, representing
REVIEWS 411
respectively metamorphosed silicious and argillaceous sediments.
Locally the base of the series is conglomeratic. “a are divided into
an upper and a lower silicious zone.
Torridonian strata occupy most of the unmoved area east of the fault
line. The beds are chiefly coarse, chocolate and red arkoses and pebbly
grits which carry occasional layers of shale and flagstone.
Unconformable upon the Torridon beds lie the Cambrian. The
Cambrian is based with a gritty quartzite; the upper Fucoid limestones
carry an Olenellus fauna.
An apparent metamorphic transition of Torridon into Moine schists
is reported, but no suggestion is made as to the age of the Moine schists
relative to the Cambrian and Torridonian.
The petrology of the district is marked by unusual lamprophyre
dikes of minette and monchiquite relationships.
The last twenty pages are given to a discussion of Pleistocene glacia-
tion and glacial deposits.
©}
The Archean Geology of Rainy Lake Re-studied. By ANDREW C.
Lawson. Geol. Surv. Canada, Memoir No. 40, 1913. Pp.
115, pls. 9, map 1.
Field study confirms the author’s earlier opinion (of 1887) that the
Coutchiching sedimentary series is older than the Keewatin igneous
rocks. He found that there were two widely separated periods of plu-
tonic activity; to the earlier he proposes to confine the name Laurentian,
and for the younger he introduces the term Algoman.
Lawson’s classification of Archean formations from the top down-
ward is as follows:
1. Eparchean interval—peneplanation.
2. Algoman. Vast batholiths of granite- and syenite-gneisses.
3. Seine series (Upper Huronian, Middle Huronian of some authors).
Conglomerates, quartzites and slates.
4. Uplift, deformation and erosion, followed by depression.
s. Steep rock series (Lower Huronian). Sediments and volcanics.
Several hundred feet of fossiliferous limestones.
Erosion which extensively exposed the granite batholiths.
7. Laurentian. Granites and granite-gneiss.
8. Keewatin. Chiefly volcanic rocks with intercalated sedimentary
beds. Certain intrusive gabbros.
g. Coutchiching. Sedimentary strata. Mica schist and paragneiss.
412 REVIEWS
Only two divisions of the Huronian are admitted, and the Animikie
and Keweenawan are not grouped with the Archean but with the Paleo-
zoics. However, these two divisions are associated under the higher
name Algonkian. He also proposes the name Ontarian to cover the
closely associated Keewatin and Coutchiching.
The major part of the report is given to a detailed discussion and
description of the criteria whereby the Coutchiching is represented to be
older than the Keewatin. The arguments presented are based upon
structural relations, and actual contacts at which the Keewatin lies
upon the Coutchiching.
The conglomerate which Lawson formerly thought part of the
Coutchiching, and which others used to show that the Coutchiching
is younger than the Keewatin, Lawson now distinguishes as part of
another, very much younger, group, the Seine series. The stratigraphical
position of this series is not clearly established, and therefore the upper
part of his Archean classification is not much more than tentative.
TRE
The Pre-Cambrian Geology of Southeastern Ontario. By WILLET G.
MILLER and Cyrit W. Knicur. Report of the Bureau of
Mines, Vol. XXII, Part II, t914. Pp. 151, illustrations 67,
portraits 4, maps 13.
The chief results of the work were to show that: (1) the sedimentary
rocks have a basement of Keewatin green schists and ellipsoidal lavas;
(2) the Grenville series were deposited upon the Keewatin lavas, but
no erosional interval has been proved; (3) granites of two ages have been
recognized; the older one is gneissoid and intrudes the Keewatin and
Grenville rocks, the younger granite intrudes all the local pre-Cambrian
rocks; (4) most of the metamorphosed blue limestones are classed with
the Grenville series, but the conglomerates and some other sediments
are younger and differentiated as the Hastings series; (5) post-Hastings
igneous rocks are gabbro, basalt, and tuffs, and the Algoman granite
which is later than the gabbro group.
Because the great Grenville limestone series (94,000 feet thick—
Adams) was pre-Laurentian, the authors think there is no special sig-
nificance to be attached to the Laurentian as an epoch-marking time.
They drop the terms Algonkian and Archean, and Proterozoic and
Archeozoic. They do not reach definite conclusions about the correla-
tion of the limestone conglomerate and other formations in the Madoc
area.
REVIEWS . 413
As an appendix the authors present their correlation of the pre-
Cambrian rocks of Ontario, western Quebec, and southeastern Ontario.
They follow Lawson in calling the older granites Laurentian and the
younger ones Algoman. They drop the name Huronian because they
think confusion of application has ended its usefulness. They group
the sedimentary rocks of the classic Huronian district at Bruce as
“Animikean,” and correlate with them the Cobalt and Whitewater
series and the Ramsey Lake Conglomerate. All post-Algoman, pre-
Keweenawan rocks are classed as Animikean. Pre-Algoman, post-
Laurentian rocks are ““Temiskamian.” This name covers the Sudbury,
Temiskaming, and Hastings series. For the group including the
Keewatin and Grenville they propose the name ‘“Loganian.”” They
think it unnecessary to retain the name Coutchiching, nor do they con-
sider that the position of those beds has been proved to be below the
Keewatin.
Their classification is as follows:
Keweenawan. Upper copper-bearing rocks of Lake Superior. Igneous rocks
are both massive and in flows. Sedimentary rocks are little
altered in horizontal positions.
Unconformity.
Animikian. Upper Huronian, Cobalt series, etc. Quartzite, arkose, con-
glomerates in usually only gently folded positions.
Great unconformity.
Algoman. Lorrain, Moira, Killarney, Younger Laurentian granites.
Generally massive, color pink.
Temiskamian. Lower Huronian, Sudbury series. Quartzites, arkose, con-
glomerate, Hastings limestone. Usually dips at high angles
and is schistose.
Unconformity.
Laurentian. Granites and gneiss. Color typically gray.
Loganian. Grenville and Keewatin. Highly metamorphosed. Lime-
stones, iron formations, and igneous flows.
at. ©)
RECENT PUBLICATIONS
—FIELDNER, A. C., Smiru, H.I., Fay, A‘H., AND SANFORD, SAMUEL. Analyses
of Mine and Car Samples of Coal Collected in the Fiscal Years 1911 to
1913. [U.S. Bureau of Mines, Bulletin 84. Washington, 1914.]
—Futron, C. H. Metallurgical Smoke. [U.S. Bureau of Mines, Bulletin
84. Washington, 1914.]
—Ger, L. C. E. (Compiler). A Review of Mining Operations in the State
of South Australia during the Half-Year Ended December 31, 1914.
{South Australia Department of Mines, No. 21. Adelaide, ror5.]
—Geological Survey of Canada. Summary Report of the Geological Survey,
Department of Mines, for the Calendar Year, 1914. [Ottawa, 1915.]
—GotptHwait, J. W. The Occurrence of Glacial Drift on the Magdalen
Islands. [Canada Department of Mines, Museum Bulletin 14, Geological
Survey, Geological Series, No. 25. Ottawa, 1915.]
—GREEN, J. F. N. The Older Paleozoic Succession of the Duddon Estuary.
[London: Dulau & Co., 1913.]
———. The Structure of the Eastern Part of the Lake District. [Reprinted
from the Proceedings of the Geologists’ Association, Vol. XXVI, Part 3,
1915. London.]
—Grover, N. C., Chief Hydraulic Engineer; and Hoyt, U. G., Horton,
A.H., anp Covert, C. C., District Engineers. Surface Water Supply
of the United States, 1913. Part IV. St. Lawrence River Basin. [U.S.
Geological Survey, Water-Supply Paper 354. (Prepared in co-operation
with the states of Minnesota, New York, and Vermont.) Washington,
1915.]
—Hackman, Victor. Der gemischte Gang von Tuntijiérvi im Nérdlichen
Finland. [Bulletin No. 39 de la Commission Géologique de Finlande.
Helsingfors, 1914.]
Ueber Comptonitginge im Mittleren Finnland. [Bulletin No. 42
de la Commission Géologique de Finlande. Helsingfors, 1914.]
—Hancocx, E. T. The History of a Portion of Yampa River, Colorado
River, and Its Possible Bearing on That of Green River. [U.S. Geological
Survey, Professional Paper 90-K. Washington, r915.]
—Havusen, H. Studier dfver de Sydfinska Ledblockens Spridning i Ryss-
land, Jamte en Ofversikt af Is-Recessionens Férlopp i Ostbaltikum.
Preliminairt Meddelande med Tvenne Kartor. Mit deutschem Referat.
[Bulletin No. 30 de la Commission Géologique de Finlande. Helsingfors,
Mars, 1912.]
Undersékning af Porfyrblock fran Sydviastra Finlands Glaciala
Aflagringar. Mit deutschen Referat. [Bulletin No. 31 de la Commission
Géologique de Finlande. Helsingfors, Mars, 1912.] ;
414
RECENT PUBLICATIONS 415
—Hawaiian Volcano Observatory, Weekly Bulletins of the. Vol. II, Nos.
28, 29, 30. (Honolulu, 1914.]
—Hay, O. P. Contributions to the Knowledge of the Mammals of the
Pleistocene of North America. No. 2086. [From the Proceedings of the
‘U.S. National Museum, Vol. XLVIII, pp. 515-75, with Plates 30-37.
Washington: Government Printing Office, 1915.]
—HENNEN, R. V., AND REGER, D.B. Report on Logan and Mingo Counties.
With Part IV, Paleontology, by U. Armstronc Pricr. Accompanied
by maps showing topography and general and economic geology. [West
Virginia Geological Survey, County Reports, 1914. Morgantown, 1or1s.|
—Hicks, W.B. The Composition of Muds from Columbus Marsh, Nevada.
[U.S. Geological Survey, Professional Paper 95-A. Washington, 1915.|
—Hi1, J. H. Some Mining Districts in Northeastern California and North-
western Nevada. [U.S. Geological Survey, Bulletin 594. Washington,
1915.|
—Hinps, H., AND GREENE, F.C. The Stratigraphy of the Pennsylvanian
Series in Missouri. With a Chapter on Invertebrate Paleontology, by
G. H. Girty. [Missouri Bureau of Geology and Mines, Vol. XIII,
Second Series. Rolla, 1o15.]
—Hinxman, L. W., AnD ANDERSON, E. M. The Geology of Mid-Strathspey
and Strathdearn, Including the Country between Kingussie and Gran-
town. (Explanation of Sheet 74.) With contributions by J. Horne,
R. G. CARRUTHERS, and C. B. CRAMPTON, and a Petrographical Chapter
by J. S. Fretr. [Scotland Geological Survey, Memoirs of the, No. 74.
Edinburgh: Morrison & Gibb, at Tanfield, ro15.]
—Hosss, W.H. The Role of the Glacial Anticyclone in the Air Circulation
of the Globe. [Proceedings of the American Philological Society, Vol.
LIV, No. 218, August, 1915.]
—Horton, A. H., Hatt, W. E., AND JAcKson, H. J. Surface Water Supply
of the United States, 1913. Part III. Ohio River Basin. [U.S. Geo-
logical Survey, Water-Supply Paper 3 53. (Prepared in co-operation
with the State of West Virginia.) Washington, ro15.|
—Horcnkiss, W. O., AND STEIDTMANN, E. Limestone Road ewe riale of
Wisconsin. FW iceonsin Geological and Natural History Survey, Bulletin
XXXIV. Madison, 1915.]
—Hovyt, W. G., anp Ryan, H. J. Gazetteer of Surface Wiener of Iowa.
[U.S. Goolonieal Survey, Water-Supply Paper 345-1. Washington, 1915.|
—Hunrt ey, L. G. The Mexican Oil Fields. [Transactions of the American
Institute of Mining Engineers. New York, 1o15.|
—Ippincs, J. P. The Problem of Vulcanism. [New Haven: Yale Uni-
versity Press, 1914.|
—JIMENEz, CarRtos P. Estadistica Minera en 1913. (Boletin del Cuerpo
de Ingenieros de Minas del Peru No. 81. Lima, 1o15.]
416 RECENT PUBLICATIONS
—Jounson, R. H., AND Hunttey, L. G. The Influence of the Cushing Pool
in the Oil Industry. [Proceedings of the Engineers’ Society of Western
Pennsylvania, Vol. XX XI, pp. 460-87. Pittsburgh, 1915.]
—Jounston, R. A. A. Gay Gulch and Skookum Meteorites. [Canada
Department of Mines, No. 1533, Museum Bulletin 15, Geological Survey,
Geological Series No. 26. Ottawa, 1o15.]
—Jones, F. A. The Mineral Resources of New Mexico. [Mineral Resources
Survey of New Mexico, Bulletin 1. Socorro, 1915.]
—Kay, F. H. Coal Resources of District VII (Coal No. 6 West of Duquoin
Anticline). [Bulletin 11, Illinois Mining Investigations. Co-operative
Agreement. Illinois Geological Survey, Department of Mining Engi-
neering, University of Illinois; U.S. Bureau of Mines. Urbana, 1915.]
—KEELE, J. Preliminary Report on the Clay and Shale Deposits of the
Province of Quebec. [Canada Department of Mines, Memoir 64, No.
1451, Geological Survey, Geological Series, No. 52. Ottawa, 1o15.]
—Keves, C. Chart of the Geologic Terranes of Iowa. [Des Moines, 1914.]
Iowa’s Great Period of Mountain Making.
———. Our Pre-Cambrian Rocks.
Serial Subdivision of the Early Carbonic Succession in the Conti-
nental Interior.
Syllabus of a Course of Lectures on Geologic Processes and Geo-
graphic Products. [Socorro: New Mexico School of Mines Press, 1914.]
—Kwnoprr, A. A Gold-Platinum Palladium Lode in Southern Nevada. [U.S.
Geological Survey, Bulletin 620-A. Washington, 1915.]
—Kress, C. E., anp TEETS, D. D., Jk. West Virginia Geological Survey,
County Reports, 1915. Boone County. Part IV. Paleontology, by
W. ARMSTRONG PRICE. With Maps of Topography, and General and
Economic Geology, 1914. [Morgantown, 1o915.]
—KREISINGER, H. Hand-Firing Soft Coal under Power-Plant Boilers. [U.S.
Bureau of Mines, Technical Paper 80. Washington, 1914.]
—LamBE,L.M. On Eoceratops canadensis, gen. nov., with Remarks on Other
Genera of Cretaceous Horned Dinosaurs. [Canada Department of
Mines, Museum Bulletin 12, Geological Survey, Geological Series No. 24.
Ottawa, 1915.]
—LEE, W. T., STONE, R. W., GALE, H. S., AND OTHERS. Guidebook of the
Western United States. Part B. The Overland Route, with a Side
Trip to Yellowstone Park. [U.S. Geological Survey, Bulletin 612.
Washington, ro915.|
—Lewis, J. V. Determinative Mineralogy, with Tables. [New York: John
Wiley & Sons, ro1t5.]
—Locan, W. N. The Structural Minerals of Mississippi. A Preliminary
Report. [Mississippi Geological Survey, Bulletin 9. Jackson, 1o11.]
—Lowe, E. N. A Preliminary Study of Soils of Mississippi. [Mississippi
Geological Survey, Bulletin 8. Jackson, 1911.]
THE SUMMER QUARTER | 3 one
OF THE UNIVERSITY OF CHICAGO A New P roposition
Afford ot . oe A TYPEWRITER BY PARCEL POST
ords opportunity for instruction on the same basis
as during the other quarters of the academic year. ON TEN DAYS’ FREE EXAMINATION
The undergraduate colleges, the graduate schools, and
It is the
' the professional schools provide courses in Arts,
Literature, Science, Commerce and Adminis-
eration: ewe Medicine, eee eae } ‘
ivinity. Instruction is given by regular members p
of the University staff which is augmented in the sum- Remington
mer by appointment of professors and instructors
J e
Summer Quarter, 1916 unior
ist Term June 19--July 26 gee
2d Term July 27--Sept. 1 the very latest addition to the great
Remington fami iters.
Detailed announcement will be sent upon application gto amily of ‘YB (ave s. Anew
tothe and smaller Remington—built for the
Dean of the Faculties needsof the professional man and thehome
from other institutions.
THE UNIVERSITY OF CHICAGO
Mail this coupon today
_ Chicago, Illinois é ie
EE Se ES Remington Typewriter Company
(Incorporated)
327 Broadway, New York |
= _Send me a Remington Junior Typewriter,
The Botanical Gazette price $50, on free examination. It is understood
that I may return the machine, if 1 choose,
within ten days. If I decide to purchase it, I
Edited by John M, Coulter e agree to pay for it in ro monthly payments of
Published monthly, with illustrations. Subscription $5 each. §
price, $7.00 a year; single copies, 75 cents; foreign
postage, 84 cents
THE UNIVERSITY OF CHICAGO PRESS CUP
< CHICAGO, ILLINOIS
Daus Improved Tip Top Duplicator
is an ideal assistant, always ready to reproduce clean, clear,
perfect copies of letters, manuscripts, price lists, bills, in-
voices, reports, drawings, menus, etc., etc. Don’t take
our word, try it yourself for
Ten days’ trial without deposit
Tf not satisfactory, return and no questions asked. Makes
rt50 handwritten and 50 typewritten copies in a few min-
utes. Negatives require no washing out after using, and
negative rolls can be used from 15 to 20 times. Complete
outfit contains a continuous roll of Daus Non-Peeling Anti-
Stick Negative Roll. Capsize,8$x13inches. Price $7.50
FELIX K. DAUS DUPLICATOR CO.
Daus Building, 111 John Street, NEW YORK
the American Library Association’s meeting to be held at Asbury
Park, June 26th to July 1st and we should be very glad to have
you visit our establishment while here. You will welcome an opportunity
“ to see how the various functions of a large book concern operate, and to
become acquainted with the facilities and methods of a business of such vital
and economic importance to your profession.
D7Ka0 doubt you will stop over at New York on your way to and from
THE BAKER & TAYLOR CO.
354 Fourth Avenue © ©
At Twenty-sixth Street Wholesale Booksellers
NEW YORK
FINE INKS 4x» ADHESIVES
For those who KNOW
Drawing Inks
Bternal Writing Ink
Engrossing Ink
e e 9 Taurine Mucilage
Hig eins’ ¢ proto Mounter Paste
Drawing Board Paste
: Liguid Paste
Office Paste
Vegetable Glue, Etc.
Are the Finest and Best Inks and Adhesives
Emancipate yourself from the use of corrosive and
ill-smelling inks and adhesives and adopt the
Higgins Inks and Adhesives. They will bea
revelation to you, they are so sweet, clean, well
put up, and withal so efficient,
At Dealers Generally
CHAS. M. HIGGINS & CO., Mfrs.
Branches: Chicago, London
271 Ninth Street Brooklyn, N.Y.
Practical Projection
Do You Want to Know
What Your Handwriting
: Reveals?
WE have published a fascinating
booklet of 32 pages on the sub-
ject of graphology, by William Leslie
French. Every reader of this publi-
cation will be interested in comparing
the examples of handwriting in judg-
ing character and disposition of the
writer.
A copy of this booklet and 12 differ-
ent patterns of The Spencerian
Steel Pens will be sent postpaid on
receipt of ten cents.
If you can do good work with a poor pen
you can do better work with a good pen.
Silver plated Falcon, pens, smooth points,
wear long, will not corrode.
SPENCERIAN PEN CO.
349 Broadway Pe New York City
for Schools
For classroom work, lecture platform, or lyceum
N use, in school or college—or for home entertain-
ment and _ instruction—every requirement of a picture projection is met by the
Bausch |omb
BALOPTICON
THE PERFECT STEREOPTICON
Our recent application of the gas-filled Mazda lamp to projection gives the Balopticon an il-
luminator far superior to the old-style arc lamp—and one using less current for equal power.
The New Combined Balopticon projects either lantern slides or opaque objects, with instant
interchange. It has the new lamp of 1,000 watts, using but 9 amperes of current, instead of
35 amperes as used by the arc lamp of equal illumination, and giving much better results on
alternating current. Price $120.00.
Other models for lantern slide or opaque projection from $20.00 up.
Special terms to Educational Institutions. Write for illustrated catalog.
Bausch €F lomb Optical GC.
554 ST. PAUL STREET ROCHESTER, N.Y.
NEW YORK WASHINGTON
CHICAGO SAN FRANCISCO
Leading American Manufacturers of Microscopes, Projection Apparatus, Photographic Lenses, Engineering Insirumenis,
Binoculars, and other high-grade Optical Products
~ VOLUME XXIV é NUMBER 5
THE
A SEMI-QUARTERLY
EDITED BY
THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
With the Active Collaboration of
SAMUEL W. WILLISTON, Vertebrate Paleontology ALBERT, JOHANNSEN, Petrology
STUART WELLER, Invertebrate Paleontology ROLLIN T. CHAMBERLIN, Dynamic Geology
ALBERT D. BROKAW, Economic Geology
ASSOCIATE EDITORS
JOURNAL or GEOLOGY
SIR ARCHIBALD GEIKIE, Great Britain JOSEPH P.IDDINGS, Washington, D.C.
CHARLES BARROIS, France JOHN C, BRANNER, Leland Stanford Junior University
ALBRECHT PENCK, Germany _ RICHARD A. F. PENROSE, JR., Philadelphia, Pa.
HANS REUSCH, Norway WILLIAM B. CLARK, Johns Hopkins University
GERARD DEGEER, Sweden WILLIAM H. HOBBS, University of Michigan
T. W. EDGEWORTH DAVID, Australia FRANK D. ADAMS, McGill University
BAILEY WILLIS, Leland Stanford Junior University CHARLES K. LEITH, University of Wisconsin —
GROVE K. GILBERT, Washington, D.C. WALLACE W. ATWOOD, Harvard University
CHARLES D. WALCOTT, Smithsonian Institution WILLIAM H. EMMONS, University of Minnesota
HENRY S. WILLIAMS, Cornell University ARTHUR L. DAY, Carnegie Institution
JULY-AUGUST 1916
THE GEOLOGICAL ‘SIGNIFICANCE AND. GENETIC CLASSIFICATION OF ARKOSE
DEPOSITS - - - - - - - - - - - - Donatp C. BARTON
AN UNUSUAL FORM OF VOLCANIC EJECTA - - - - WALLACE E. PRATT
RIPPLE-MARKS IN OHIO LIMESTONES_ - - - - - Cartes S. Prosser
THE RELATIONSHIPS OF THE OLENTANGY SHALE AND ASSOCIATED DEVONIAN
DEPOSITS OF NORTHERN OHIO - - - - - - - C. R. STAUFFER .
EVOLUTION OF THE BASAL PLATES IN MONOCYCLIC CRINOIDEA CAMERATA. I
Herrick E. WILSON
VARIATIONS OF GLACIERS. XX - : = bids tease ar - Harry Frerpivc Rep
REVIEWS - - - - - - - Ea = < - = i ee z uh is
RECENT PUBLICATIONS - - - - e = = A y es a 4 =
THE TUNIVERSITY OF (\CHICAGO” PRESS
CHICAGO, ILLINOIS, U.S.A.
AGENTS
THE CAMBRIDGE UNIVERSITY PRESS, Lonpon anp EDINBURGH
KARL W, HIERSEMANN, Letpzic
THE MARUZEN-KABUSHIKI-KAISHA, Toxyo, Osaka, Kyoto
Pee THE MISSION BOOK COMPANY, SHANGHAI
4l7
450
456
476
488
THE JOURNAL OF GEOLOGY |
EDITED By
THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
With the Active Collaboration of
SAMUEL W. WILLISTON : ALBERT JOHANNSEN
Vertebrate Paleontology Petrology
STUART WELLER ROLLIN T. CHAMBERLIN
Invertebrate Paleontology Dynamic Geology
ALBERT D. BROKAW
Economic Geology
The Journal of Geology is published by the University of Chicago at the University Press semi-
quarterly, on or about the following dates: February 1, March 15, May 1, June 15, August 1, September 15,
November 1, December 15. {| The subscription price is $4.00 per year; the price of single copies is
65 cents. Orders for service of less than a half-year will be charged at the single-copy rate. { Postage is
prepaid by the publishers on all orders from the United States, Mexico, Cuba, Porto Rico, Panama Canal
Zone, Republic of Panama, Hawaiian Islands, Philippine Islands, Guam, Samoan Islands, Shanghai,
] Postage is charged extra as follows: For Canada, 30 cents on annual subscriptions (total $4.30), on
single copies, 4 cents (total 69 cents); for all other countries in the Posta] Union, 53 cents on annual
subscriptions (total $4.53), on single copies, 11-cents (total 76 cents). {| Patrons are requested to make
all remittances payable to the University of Chicago Press in postal or express money orders or bank
drafts.
The following agents have been appointed and are authorized to quote the prices indicated:
For the British Empire: The Cambridge University Press, Fetter Lane, London, E.C. Yearly
subscriptions, including postage, 18s. 8d. each; single copies, including postage, 3s. 2d. each.
For the continent of Europe: Karl W. Hiersemann, Konigstrasse 29, Leipzig, Germany. Yearly
subscriptions, including postage, M. 22.65 each; single copies, including postage, M. 3.80 each.
For Japan and Korea: The Maruzen-Kabushiki-Kaisha, 11 to 16 Nihonbashi Tori Sanchome,
Tokyo, Japan. Yearly subscriptions, including postage, Yen 9.00 each; single copies, including
postage, Yen 1.50 each.
For the Chinese Empire: The Mission Book Company, 18 Peking Road, Shanghai, China.
Yearly subscriptions, $4.00; single copies, 65 cents, or their equivalents in Chinese money, Postage
extra, if mailed direct outside of Shanghai, on yearly subscriptions 53 cents, on single copies II cents,
Claims for missing numbers should be made within the month following the regular month of
publication. The publishers expect to supply missing numbers free only when they have been lost in
transit.
Business correspondence should be addressed to The University of Chicago Press, Chicago, III.
Communications for the editors and manuscripts should be addressed to the Editors of THE
JOURNAL OF GEOLOGY, the University of Chicago, Chicago, Ill.
Contributors are requested to write scientific and proper names with particular care and in citations
to follow the form shown in the pages of the Journal.
Separates, if desired, must be ordered in advance of publication. Separates of leading articles will be
printed as ordered, of which 50 (without covers) will be furnished gva¢zs, the actual cost of the remainder
(and covers, if desired) to be paid for by the author. The actual cost may vary, and will depend upon
the amount of work in re-making the pages into forms, presswork, paper, binding, etc. Separates
containing half-tones may be expected to cost somewhat more, the increase depending upon the number
of cuts and the amount of work required upon them.
Entered as second-class matter, March 20, 1893 at the Post-office at Chicago, Ill., under the Act of March 3, 1879.
‘hee m
a ee a oe
VOLUME XXIV NUMBER 5
THE
hROURNAL OF GEOLOGY
JULVAUGUSE 1016
THE GEOLOGICAL SIGNIFICANCE AND GENETIC
CLASSIFICATION OF ARKOSE DEPOSITS?
DONALD C. BARTON
Arkose has been held by different geologists to be significant
respectively of several different types of conditions at the time of
its formation. By Walther,? for instance, it is considered to be so
distinctive of desert formations as to be, next to salt deposits, the
the most important index of. the desert origin of a formation.
Mackie,’ although not mentioning arkose by name, in his discus-
sion of the significance of fresh feldspar in sediments seems to con-
sider the rock especially characteristic of deposits that have formed
under rigorous climatic conditions. Von Hauer‘ believes that
arkose is especially characteristic of coal-bearing formations.
Shaler is of the opinion that it is formed when a granitic terrane,
long under moist temperate climatic conditions, is exposed to more
rigorous conditions or to marine or lacustrine transgression. Mans-
field® believes, on the other hand, that the conditions for the formation
t Portion of a thesis accepted in partial fulfilment of the requirements for the degree
of Doctor of Philosophy at Harvard University.
2 J. Walther, Das Gesetz der Wiistenbildung, 2d ed., p. 174.
3 William Mackie, Trans. Edin. Geol. Soc., VII (1898), No. LV.
4 Franz von Hauer, Die Geologie, 1875.
5 W.S. Shaler, U.S.G.S. Monograph XX XIII, 1899, pp. 50-55.
®°G. R. Mansfield, Bul. Mus. Comp. Zoél. Harvard, XLIX (1906), 293-04.
Vol. XXIV, No. 5 417
418 DONALD C. BARTON
of arkose are intermediate between these extremes, and that
a moderately cool and arid climate such as would prevail at mod-
erately high altitudes in the lee of high mountain ranges or in con-
tinental interiors would more probably be suitable. The present -
paper is an attempt to delimit the significance of arkose.
The fundamental conditions essential for the formation of
arkose’ are: (a) a granitic terrane, (b) conditions favorable to the
disintegration of the granite or gneiss with but slight accompanying
decomposition, and (c) conditions favorable to the erosion and
deposition of the débris of disintegration with merely slight loss
of the feldspar. In the investigation of the regions which today
can supply débris of disintegration for the formation of arkose
(Figs. 1 and 2), it was found that disintegration is much more
widespread than is perhaps usually realized, and that it takes
place in marked amounts under practically all the conditions under
which a granitic terrane is exposed (see Table I, a list of the occur-
rences of disintegration which have been observed by the writer,
or which he has been able to find described in the literature, together
with a tabular view of the conditions under which the disintegration
is taking place). The investigation of the conditions under which
the disintegrated material could be eroded and deposited as arkose
seems to show that in some cases the conditions favorable to the
disintegration are likewise favorable to contemporaneous erosion
and deposition of the disintegrated material as arkose, as, for
instance, in desert regions, and that in other cases erosion can take
place only after some change of conditions, as, for example, a
change from the conditions of a moist temperate climate to those
of a semi-arid climate. In yet other cases, erosion may take place
contemporaneously with disintegration but be followed by decom-
t Arkose by original definition and according to most general usage is a rock
formed of the relatively undecomposed débris of granite or of rods of granitic mineral-
ogical composition. It may be thought, however, that the original definition should
be extended to cover feldspathic clastics derived from the disintegration of syenites,
diorites, gabbros. Feldspathic clastics of this type, however, should be rare, since
there are practically no purely syenitic, dioritic, or gabbroic terranes, and since the
plagioclase feldspar of the diorites and gabbros is more or less readily decomposed.
No specimen of this type of feldspathic clastic has been seen by the writer, and only
one or two reputed occurrences are reported in the literature.
Loca
EK
S.E. Ireland . lies
Dartmoor, Engl
Forez, France. |
Plateau Central)
|
|
|
|
|
NTER TEMPERATURE
Morvan, Francéut the same as above
Hohkénigsburg
Alsacee ice Sib
Heidelberg Shee, .
|
Adlersberg, Thi, .
Grimsel Pass, A. .
Mer-de-Glace, A d
Aswan, Egypt. r.
Pyramids of Giz,
Bushmanland, ¢.
Tits
th
a)
Himalayas.......
Ceylone sos. |
Lung-wang-shar, ie
Around Inland § :
Mt. Chocorua, 1 ..
Jackson, N.H.....
Rockport, Mass.
Sykesville, Md.) .
Washington, D.|.
H
Richmond, Va...
Georgia...... 4.
\t-
)
Tron Mt., Mo...
Mt. Stuart, Was.
Wasatch, Utah ,.
Butte, Mont.. .).
Pike’s Peak, Col ..
|
Globe District, 2.
California: si
Sierra Madre, .
Lower Califerni¢ .
Valparaiso, Chil, _
Sao Francisco, E |.
Min Mean
sl) 2186 43 F.
(Mean
min.
Jan.)
7F. 36 F.
Lil Seaevaiten este 34 F.
St a octets 34 F.
21k. 32F.
45 F. 62 F
30 F. 55F
aie oe 80 F
SEAR Io F.
B aieichinecaye 32F
—13F. 65 F.
(For
Boston)
—8F 44F
45F 74 ¥F
—29F 24 F
eee ee: 6F.
22F 50F
Re oeyete 62F
a Vnchaparenete 82 F
RAINFALL
aL
4
+ in Oct.—-Nov.
REMARKS
Medium-grained granite
Coarse porphyritic granite; fine-
grained granite not affected
Coarse and porphyritic granites;
fine-grained granite not affected
Coarse, porphyritic granite
Coarse, porphyritic granite
Medium-grained granite
Monthly
Summer] Winter
4 in. 5 in.
4 in. 5 in.
4 in. 3 in.
)
° °
fo) 0.3in
12 in.
1.5to4|1.2to2
in. in.
AAT 8\| (Seyret te
in June and July
oin. |r to 2 in.
Medium-grained gneissic granite
Medium-grained gneissic granite
Coarse, porphyritic, biotite granite
Coarse, porphyritic, biotite granite
Medium-grained pyroxene granite
Medium-grained, with a slight
amount of biotite _ :
Medium- to coarse-grained granite;
hornblende granite
Fine-grained biotite granite
Moderately fine mica granite
Medium-grained mica granite
Fine- to medium-grained, porphy-
ritic mica granite
Medium-grained granodiorite
Medium to coarse-grained mica,
hornblende, quartz monzonite
Coarse to coarse and porphyritic
granite
Granodiorite
Granodiorite
Fe-bearing minerals decomposed
Fic. 1.—Distribution of the occurrences of marked granular disintegration as reported in the literature or observed by the writer.
TABULAR VIEW OF THE OCCURRENCES OF DISINTEGRATION AND OF THE CONDITIONS UNDER W
TABLE I
HICH THE DISINTEGRATION Is Taxtnc PLACE
RAINFALL
3 DEPTH To Warcu| AMOUNT OF DE- SuaoreR TEMPERATURE Winter Tew:
Lat. | Lone. | Torocrapay ELEVATION BOLLUATION ore Depta to Warcy Dis- | tye coxposrtion |q COMPOSITION | VEGETATIVE CovER- s SERRE
LocaLit¥ GRATIO INTEGRATION EXTENDS TSSaS SHowN By Distn- ING Monthly REMARK
TEGRATED RocK | Yearly —
. . la
Max Min. Mean | Max Min. Mean | Summer} Winter
windee 53 N. 7 W. | Mature to old WRONG |s6o565e58e8 cn00| endo cnnacecbosonocuee: | poe asecedunenccel be asudenonenonoL Grass and brush |........].......- Pe al Meee |S nea Pea can AW in
gp. Ireland «---+" an F ‘ sses} Soin, ‘ sin.
ogee stN.| 4W. 1,500 ft. General 6 to rs ft. 3 to8ft. Local-| Considerable Heather and moss | 68F. |........] 60F. |........| 3 3 i ; i
Partmoor, England. «-« a ds of f bun (Mean max. into) i fen iS Seite Soi fcada. Sin. | Medium-grained granite
reds of fee ; :
min.
5 Jan.)
ae 4s N. 4 E. Nod 1,500 ft. 1 Noticeable Grass and woods | ae automa fey WS | boats Sse 36F 9 ; . +
Forez, France: i ncuaee 46 N. 3 EI 5 Genera To to 30 ft. to 4 ft. thoughiaoe 95 (Man Sine 7F. 36F. | 32in. | gin. Sin, | Coarse porphyritic granite; fine-
Plateau Central, Fre . B ltora eK a ' : - F ee advanced grained granite not affected
/ nas i eneral 5 to 25 ft. 1 to 4 ft. oticeal ‘ASS 2 v
ita ranceneeenerre?e 47 4 ae ae Grass and woods About the same About the same as above |........{e. ccc ce cde sec ee Coarse and Rerahyritic granites;
very advanced | fine-grained granite not affected
mi wes Mts.,
fohkanigsburg, Vosses 3.N. E. | Mature 1,500 ft. General 8 to 20 ft. plus 1 to 4 ft. Noticeabl Fores : eau Pon ~
Hahn Le iereke|| <4 7 r 04 aaa oe INTE = [logo nndllocoascus (YO |isspe3 fon) bonedscn 34 FP. UY. |andosue | Rratstercntete Coarse, porphyritic granite
very advanced
. j E. | Mature 800 ft. General to ro ft. 1 ft. Noticeabl F a4 FE wah A aie
Heidelberg Shect..--- +++ 0+" 49 N 9 s thee et Forests) nny | sestetaieers | eitenietars CEOS | eons cq) soneoune 34 F. Gans | okereerers | hiertaenrahe Coarse, porphyritic granite
. very advanced
ey 3 E. | Late maturit AI, = Wesgandocacooars to 8 ft. 3 Noti oF 32 F , . ;
Adlersherg, Thirringerwald . I SXEN 11 y sto 8 ft 1 to 2 ft “though not Forest = © ||Ratemecel| Soisrcis sta] tieeneccisn hoe eee 2F. RE) oh Vl ogoacian pucknond todirotesd Medium-grained granite
very advanced
0 , glaciated 6 i f i J i ig! ei-K 9 . - =
Grimsel Pass, AIDS. .-+-07+* 47 N. 8 E. Boung, slacia e 500 ft Only valley seen} Superficial 8 8 = |................ Very slight Light or none (Rigi-Kulm) RX) Ona Peettors Sas| eoodo tod Runoporal osostned ncacacd cera Medium-grained gneissic granite
Merde-Glace AlpS.ceee cere 40.N. 7 E. surface of alpine 5,500 ft. Surface Sicsitiel = ane cansanoccand Very slight NOT CS 8 opeerond bsdodard sopaceed onde tcl hoo ona) saqdecad acto camo maancaurd ke Medium-grained gneissic granite
etle-Grace, “Oi glacier eS 3 a
7 ; LE. | Shall oun 00 ft. i ia 2 | a 2F. R : nae Be Oh ‘
Avan, Egypte esvceeeeerers a4.N. | 32 alley 14 400 General Superficial, locally 10 ft.) None Torche mort part None 112 LN eee aS 1 oof 4sF 62 F. a) ° ° Coarse, porphyritic, biotite granite
Pyramids of Gizch, Egypt.-..| 30N. | 31 E. paremids ona Less than 400 ft. Surtaceiof the ees. Sue) ileatosaBencoodoas Very slight None 104 F. 64 PF. 82 F. 75 BR. 30 F. ssF. | xr.sin ° 0.3 in, | Coarse, porphyritic, biotite granite
Gindbssserececeenernenrerer SINE |) Ky BO) BOL be phaneanaaenpsced Valley sides artlyssuperticial aan | ettectciseretel erie Very slight 1\ Ci nn Soe poeas ssonasee| Poasomadl adoot 10 dllecsoacedlonqostsee MEP} Segdosn|lavoasnae
CORSE al a than
roin
S, Africa....-| 30 S. fe} 105 |k. Anneetoadoo sons dlacsgcontonoooaisend sodmoaodada apie SUDETCia] Me | (essen Very slight None or very light ]........]........ sr F. EPI. llsnananas|jasoceoud Less
Hushmanland, S ~ (Coldest (Warm- han
month) est ro in
month
mean)
Himalayas, .ss+ 20 GonGuGOO 34. N. | 76 E. | Young, moun- Above 44,000 ft. | Exposedsurfaces} Superficial 8 = |..............-. Very slight None se GB reaetoces | frases | Sosnreers AA chal loemnocod laaaqooenl Ketneacd Hatheeah hociicanc!
tainous
Ceylon. sss ccrcseesereeeers 8N.| 80 E. | Mountainous |.................. General Few feet GQianF nna ntencucessane Forests smn | sect tetcseys £2 eel esood onllondnooed 80 Fr Over |} in June-July
so in. |} in Oct-Nov.
Lung-wang-shan, China ..... 4x N. | 124 E. | Mountainous |................. Rolling alley “Tiefgreifend”” Slice h (inne eerste erst Nome et eteteyetstetite! | nverersrererax 75\Be: [ieee = Siete] cereinieiere 10 F. Op ockecerel hecannc
in mountains
Around Inland Sea, Japan ...] 38 N. | 138 I. | High coast hills ].................- @ayae flan canueooeooegs sagiceannn Slight Very slight egneyee Haag conelicononce FAPLOH: lence, ool ooumenae 32 FP. 85 in. 7in oin
Mt. Chocorua, NH... 0... 44.N. | 71 W. | Mature, moun- 3,500 ft. Summit and Mostlyjsuperficial mes! Sete eetetletertetiele Very slight Mostlysnome;ssOme) frelateretersiel| tierra erorete|(evehsier eh tent |(cxeverercl@tatel | etetetareratere | (etetsteyar sists | eturstatertcts | ciateearencitte | Rretetetereraes Medium-grained pyroxene granite
tainous flanks of forest
: mountain
Jackson, NW... AUCOURUOD 44.N. | 71 W. | Mature, moun- joo ft. Valley 5 ft. plus Slight Noticeable Rorestuand serassia| ererrelaere | eeetrerersters)| chetereteterars | steecate iS AllapBeearcl MEROOROA HoBobood loadanatd| actrorscac Medium-grained, with a slight
tainous though slight ; i é amount of biotite
Rockport, Mass......seee ee 43. N. | 71 W. | Glaciated pene- zoo ft. Chiefly shown in| Superficial = =... . 0.0 eee Noticeable Lichens 100 F 45 F 65 F 70 F. 45 in. |3 to 4 in./3 to 4 in.| Medium. to coarse-grained granite;
plain glacial boul- though slight (Bor ) hornblende granite
ders oston
Sykesville, Md... ..cssseees 30 N. | 77 W. | Old 4oo ft. Surface generally} 30 ft. plus and minus 1.53 i tn | petetetor sdoaRenobeN Grass and forest See Washington Ant cojlooboanoo Inoooacool rar Sets | aersrane saislecsia's ....| Eine-grained biotite granite
Washington, D.C, .s.sseeeee 39 N. | 77 W. | Old 50 ft. Surface generally] 20 to 80 ft. Considerable Combis at| Grass and forest 104 F. 36F. 75F. 78 I. jrin, |3toqgin| gin, | Moderately fine mica granite
surface com-
plete ; P i * .
Richmond, Va... cece eserves 37 N. | 77 W. | Old 50 ft. Surface generally| 10 ft. plus 5 ft. plus Considerable; at} Grass and forest SeeWashington Jue fiuleieecewe|eeercees|aeesnese|isinest ss) sssiern es Medium-grained mica granite
" surisce com-
; plete : A . 0 t , '
UTA snungonnoasnn Dnacen 34.N. | 84 W. | Old 1,200 ft. Surface generally| Incipient decay to 350 ft.| 95 ft. Considerable; at| Grass and forest 100 F 5s F. 75T. 73K. | -8F. | 44F. | goin. [3 togin.) sin, | Fine. to medium-grained, porphy-
(around Atlanta) saree com- (tos - ritic mica granite
plete lanta ‘ ‘
Won Mt, MO csseseece ees 37 N. | 01 W. | Old 1,200 ft. Surface generally} 20-80 ft. 20 to 8o ft. Consider ble; upeobonaanonsocosdn 105 F 45 7F (I 76 P. 457 74F. | goin 4in |2to2a.s5
surface com- in.
Mt$ Y plete : i i i
Stuart, Washi.....seeee 47 N. | 121 W. | Ruggedly moun- 9,470 ft. Summit and ex-| Superficial 8s [www see eee Slight Wight) ~ © © |! steyeyerer[
CLASSIFICATION OF ARKOSE DEPOSITS 4I9Q
ae | Set
ATU ISB
hy eeieers
eerie!
ruse
Fic. 1.—Distribution of the occurrences of marked granular disintegration as reported in the literature or observed by the writer.
DONALD C. BARTON
420
Ss !
“IOWIM IY} Aq paaresqo IO 9INYVI19}I] VY} UT poz1odar se s}isodap asoyIv Jo 9dUEIINIQ—"z “OIT
. or or oe co oF 09 0; cy oor ‘on roy co oF ont on oir oar ou oy Ost oer coy or ou oo g
= Ra oe ——— oo =
| ve vy —
wes
se uted’ = !
os 2 '
"'S : i.
, 4 > a 0 [ =! P 4
; fs I a MM
‘| o
vie
2
fais
i
PR
&
7 os oF "oe oz ot oF
Be
“op. Os °°
CLASSIFICATION OF ARKOSE DEPOSITS 421
position of the feldspar, with the consequent loss of the material
as a possible source of arkose. It was therefore found impossible
to limit the significance of arkose to significance of any one or two
special sets of conditions. The arkose deposits forming under the
different conditions should expectedly be of certain characteristic
types, which as a matter of fact agree with the types of arkose
deposits as they are found (see Table II). The genetic classification
of arkose deposits which appears in the following pages is therefore
intended to embrace these various types of arkose deposits.
GENETIC CLASSIFICATION OF ARKOSE DEPOSITS
Arkose deposits may be divided broadly into two classes:
(a) those formed directly through the effects of rigorous climatic
conditions; and (b) those formed, at least indirectly, through the
effects of moist and more temperate climatic conditions. The latter
conditions allow much decomposition, which, however, commonly
takes place at a slower rate than the disintegration. The arkose
formed directly or indirectly under these conditions therefore has
feldspars showing considerable decomposition, has in many cases
a matrix of argillaceous material derived from the more easily
decomposed grains of feldspar and other silicates, and is associated
with beds of argillaceous material derived from the totally decom-
posed portions of the rock. The former conditions are unfavorable
to decomposition, and the arkose deposits forming under them have
comparatively unaltered feldspars, have little or no argillaceous
matrix, and are not associated to any great extent with argillaceous
beds. The distinction, however, is not absolute. At Aswan,
Egypt, in a region in which no rain is recorded over a period of
many years, the disintegrated granite in some places shows marked
decomposition, and the feldspar of modern arkose deposits in the
beds of the wet-weather streams of the region is deeply decomposed.
In regions of moist, temperate climate it is not uncommon, on the
other hand, to find below the zone of complete disintegration a
zone of rock which to the eye seems fresh but which crumbles
readily under blows from the hammer, and from this rock, within
a region of moist, temperate climate, it would be possible for arkose
with relatively fresh feldspar to form.
DONALD C. BARTON
422
Ssurppoq
-ssoia. ‘syuuid = dorpures
‘syovIo-pnyy ‘ossoOyIe ov
Spoq AY-AJ1OJ JO JNO DIT,
97IS
zjrenb oy} Jo asvyd ouo ssoyry
yy ynq ssoyre you ATqissog
a}ULIZ 9Y} OVUL SapeIs ssoyly
IPURIS IY} OUT pue
ayizyrenb our YoOq uoTIsuRIy,
uolyPoy
-1}81}S OU IO 9]}}I] YIM osoyTy
peyesys [Pa speMAII4)
paevadn sur
-peis ‘aseq ye osiv0d ‘osoyIy
poqysosse Ay100d ‘ensure surery
xLI}eul ouy ut redspyay
poAvoop pure zyienb svjnsuy
X1I}eU OUT
pue vor ‘siedspyey ‘zj1en()
spueq AAvoy UT
I}IIIsS pue asoz}1eN¢)
siedspyoy puv zyrenb ‘sures3
SULYPOIO}UL «= “SUL YOOT-OTFIS]O YT
asSeIO
-1svid pue zy1enb ssepoyj10
JO SUIRIS Iv[NZuUR sso] 10 dIO[T
redspyay
pue zjienb jo sayqqod pure
SuIvIs PopuUNOI sso] IO IIOP,
asoyie pur ‘9}vI10
-wo[su0D pur 9uU0}js
-purs ‘sys ‘aeys poy
APULIS PURBES
asOyLY
asOYIV
9}1Z}12NQ)
aye190
-Wwosse ‘a}TWIOTOp ‘931Z
-yarnb ‘oysemAoIs ITM
ayUPIy
dSOYIV
O}IUVIL)
asOyl
peed aecs
dSOYLV
ayoeMmAdIry
9}1Z}1"NC)
ayIeM
-A913 pur ‘9}eI1IWO[SUO0D
‘oyizjienb ‘oyWOTOp YIM
asOYIY “VJ oor
dyIVMADIS PUL ISOYIY *}J CO
MpeMAIIS pure 941]
-[Is1e pure ou0yspues pay
"yy OFZ
NVIVENVO-dad
VOIMANV HLYON
SyILUIy,
asOyIY JO 1o,vILYD
u0rq9ag
“SIM ‘TOA
4S “UOIJRULIOLT UO STUWLYy
sInoT
95110 ALO
Jowoedns ayv'y ‘yo1y4stcy
soyousg ‘9}R[S zyienb ‘asoyly
“WUO “pen? JAY Youd]
“WUO “WLASIC
SuIssIdINN ‘asoyie SUTUeOSTUIO T,
‘quo ‘WeqoD ‘osoyie oureI0'T
‘yug ‘Ainqpng ‘asoyie Pyo soddog
IX ‘X ‘TIT sesuey ‘yoy
4G ‘OAR APMLIION :daqGan()
(qsvoo ysva) Avg uospnyT
UOIZdY PUP UOT}RWIO J
NOILVAYASHQ IVNOSYTG HONOYH], YO AWALVAALI'T AHL HONOUHT,
UAL, AHL OL NMONY Siisodaq ASOMAY AHL AO SNOILVIOOSSY GNV ‘AALOVAVHD ‘AONTANIOIG AHL AO MAIA AVINAV,
Il WlaViL
423
CLASSIFICATION OF ARKOSE DEPOSITS
931z}1enb ay} Jo osvyd v asoyIY
oq1zy1enb
dq} JO [eseq 94} SI dsOxIe oY,
poy10suyy
aqzyrenb ay} Jo aseyd yeseq
ayeUIpPIOgns v A][vII SI BSOyIY
SUIPpoq-sso19
‘syurid doipurei ‘syor19-pnyy
oTYydr0ureya JL
XLIVeUL OU UT Ivdspyoy pue
zyienb = papunor AyeyeIIpoyy
X11] VUL
9} 119S-Z}1eND poureis
-ouy =e ul siedspjay pue
zyienb papunoil Ajaye1opoy[
9}VIDWIO]SUOD IISOYLY
auojspues Avis pure poy
auo}SOUN'T
SsIous puv oTURID
9} eIOWO[SUOD VSOYIY
a}IZJAeNC)
UOJSOWNT
dUO}SOUN] puv ozTURIT)
aSOYIV PUL 9}1Z}.1eNC)
dU0}SOWNT
ssious puv o}1URI4)
d}PIOWO[SU0D =|
pue asOYIe YIM 9}1Z}1eNC) {
sUO}SOWN] pur
ouoyspurs d1y}edspyoj
pue ‘oyxoemAois ‘9327S
-OFIV YIM 9} eIIWIO[SUOD
asoyie pue }"zy 1&2
"yy O00'S
—oS¢
“yy OOS‘T
—006
“yy 00S‘z
—oof
JUOWLIIA 0} VISIOI) DISOYIe uvlquiey jo oseq oy],
NVIYaNVO
poesoydioweyz yy
SNOIETIIBIV 9S0zZ}1eN()
IIOP Z11eNC)
OqT[Is1v asoyre =)
pue 9}e19WIO[SUOD ssOyTV {
9U0}SOWTT
aque
aISOyly
d}IZJILNC)
d[Is1e puv 9uo}soUTT
asoye
0jUT SuIpess ‘ouojspues
ayyM pue ‘por ‘uMmoIg
auo}spues yurd
pue o71yM ‘ouo0}sUMOIG
‘QUO}SpURS Pot PUL 9}IT
W9°0
“VJ COg'I
*qy OOS‘T
91ST [A JO ses
JAOPDAQDT
JUOUIIN A pur s}yosnyo
-eSSeT, ‘UOTVEUIO JUOUTIOA
Aasiof
MON ‘9}1Z}JIVND a{[IAUO}STIpav yy
euI[OIR)
‘UOT}BUWIOY prIqaous
SIDS pay) Udaysvy
YON
oJOD “pend
ouNUIYS ‘d}eIOWIO[SU0D ONeOFT
‘Od
‘uoAuR) Jloq;y ‘UoTRWIO, 39g
UISUODSI\ ‘QUO}SPURS LIUITIO
DONALD C. BARTON
424
saoRJINs poyeq
-uns pu sjurid dorpures sey
yoryM ‘ayeys pot oy} YA
pappeqiejut — pappaq-ssoi9
yonut 10 dAISSeUI—o}TURIS
OJUL Sapeis ssoyIe AT[RIO'T
auojspurs 94}
jo oseyd yeseq & SI 9sOyIV ay,
UOI}VIYIVLIYS JULIET
ayUeis
24} OUI sapvis ssoyIe jeseg
SYILUIIY
Jojoo ut Avis yIoq
*XLIJeUL OUTF YIM 9S0z}1eNb
poureis-ouy ssoyie soddq
ISIVOI—XU}VU UT T
oye)
asOyly J oor >
a[eys pay yjoor >
9} P1IWIO[SUOD
pue |eoo pur 9ssoyie
‘gjeys pue ouo}spurg “yj OOl <
asozyienb uazjo a10ur ‘o171
“URIS SOWIT}IWIOS ‘asOyIR [eseg
SNOUAIINOAAVO
aqui)
asoyle
ystuse13s pue YsIppory “3y Ob—of
souvivodde ur dy1URI4 QUO}SPULS
NVINOADA
SSI9US-o} TURIN)
ayizjrenb pure ssoyly “jf Og—z
doy dUO0}SOUI’T |,
j Jah ((olora
ye o1V1ZJ1eNb saurosaq ‘WLIO; a}¥IS pur dUOJSOUT’T {
-Tun a10ul ‘19uy ssoyire raddyQ asoyly “J Oof
xiyew ouy ur zj1enb —007
pue siedspjoy ‘aouvired aT[Ls1e “AI “44 COS
-de ul o1jtueis ‘asoyie yeseg —OST
NVIaNTIS
sslous pur oye)
saseyd pur x11}euUl
SOI YIM 94}1Z}IeNC)
ArAydiod pur oyu
ayizjrenb pur ssoyxly “yy Of
Arp pur lay oie
asizoo ‘ssoyry |‘pues useIS YIM pues ‘IID [
panuyuoj—NVIAANVO
asOYIY JO JojovieyD u01q99S
UISeg JOSUvdvIIT Ny
purjusei4y ‘auo}spurs O¥[eBT
"HN “voy AWT
‘Zl1y ‘vaqsig ‘a}Izj1eNQ) esjog
PULOYLLYQ ‘VUOJspuvS URdvIY
uolsoY pue uoTzeUWIO,T
Pero A Lay di
425
CLASSIFICATION OF ARKOSE DEPOSITS
SOSU9]
IO spoq YIy} Ur ssoyIy
gsoyle Jeopie~sng se owes
‘Oyo ‘syoRIy 9]
-das ‘syurid dorpures ‘syaei9
“pout yy 3eyS ~PePPpeq
-SSOID YONUE v[RYs Jnq spoq ][V
UOWUIOD SUIPpeq-sso1g
a WERE PMloy SME BO REG
UOWUIOD SUIPpeq-sso1g
as SIPEKEL PERI SMR BO ENE
S[ISSO}
-quejd §=SurArzed = suorjeyeo
-I0JUI 9[eYS pol YM ooyxIy
P9IPPeq-sso1o ssoyly
SnOIaJIUOG
-ID 94} Jo asvyd [eseq osoyIy
ISOYIV JVOPIVSNG Sv sues
[WHoJeUI SNOsdeTIISIV JO XIIARIY
S}IIS JISOYIV 0} pur
ISOYIV IIIUVIS 0} 9} eIIWIOTS
-U0D ISOYAV WOT] SOLIVA ISOYIV
Ystppot SyxoOr TLV
ysippor ‘ysnor ‘asivog
YSIpped pue 9s0z}1eNQ)
AvIS SNOIdBOTUL
‘gouvivedde ut o1jtuRIs
‘pouieis-ouy pue wIniIpoyy
_ Avi8-ysippor *A}}118 ‘asrv0y
ARIS ‘9SIvOD
aseq 94} }¥ 9710
-WO]sU0D pue adIsOyIV
pure o9]eys pot suwos
Y}IM ouUO}SpuRS AVIS 0} *zj COI‘E
YSIMo]aA pue Ysippoxy —oo*z
“JJ 009'E
aTS1y — —Oog*T
SSIoUS Pue o}TURIN
asOyIV aseq—ovys
YUM 9} RIOUIO[SUOD
pue souojspuvs dISOWLV
SIEuS
auo}spurs
OISSVIUL
per ][z—ouo}spurs
pur ‘ayeys ‘o}e19WI0;SU0D = *7y. COST
0]UI SUIPLIS VsOyIV YSNoyYy, —oo$
auoYS (aSOYIP)
-OUIT pur ‘ayeys ‘soye1a = -yy. «Sz
-wojsuo0d ‘s}Is ‘asoyry (e104)
SoUO}SpULS YSIPpoy “IJ CoS‘1
NVINaudd
SJUJUIIpEs puv 9}1URID)
ISOYIV
ISOYIV
SYA [PEEL “ak C19)
spoq
[eoo uly} YIM oseys
pue ‘auojspues ‘asoyry “3 OFS
"PIN “EN “ACN ‘9S0¥1V 107319015
“UUOD PUL ‘sseP “IOATYT
yNoauuO, ‘ssoyIy Jroy avsng
‘o]OD ‘UOTRULIO UTe}UNO,T
‘O[OD ‘UOT}VULIO J9]IND
BI}JOIG VAON ‘SITIIG W0IOFT
‘eATM “STN
youvig Moprayy ‘ayeyS sIoATY
"PAM “SIA Tourrg
MOpray, ‘UOVUIOT aM xoY
asoyie
ay} pur oyeys oy} Ur SsyxIeUL
-gjddiu pue surewer jug
soyeys oy} ul pue
dSOYIV oY} Ul SUTeWIOI JUr[
yuosoid sjueyd pissoy
z
5
Re ISOYIV OY} UT STISsOy OUTIL]
=i
isa)
S)
Q
eS)
=
=
Q
UOUIUOD
SUIppoq-sso1d "suOZLIOY
[[@ Ayavou ye speq ur ynq
aseq 7e ATUO JOU SIND9O BSOYIV
SyILUIDY
Aqye9 0]
SnOddLUOGILI ISOYIe puv a[vys
pesodurosa(
Spoq YOry} ut ‘aAIs
“seul pure privy “‘ouy 0} asIv0d
OATS
seul ‘Ud015-y1lep ‘pouless-ul yy
AVIS ISOYIV ULL]
ysippor osoyie roddy
X11} PUL
poureis-ouy = =out = sivdspypoy
pue zjienb sureis airpnsuy
souvivedde ur oIV1UeI4)
asoyIY Jo JayoRIeYyD
Surposoid oy} 0} reps Aa
asoyIe
pure gyeys ‘auo0}satuty
puv ou0}spurs SUTYeUIOITY
asoyie pue ‘auoyspurs
‘QUOYSIUNTT [JIM sayeys
snosseuoqied pue Yxory{q
SNOUOVLAYO
ayluris
‘Avp pue ‘asoyie ‘pues yy ost
NV@HONVWNOO
9}VIIWIO[SUOD PUL ISOYIV
ISOYIL-9}LIOIp pur
‘saqRIs ‘souojsouy oanduty
asoyie pure ‘soqeys ‘syn 7,
oissvaal
oyUPI
dsOyy
a[eys ‘souo}spurg “jj COf—-o
souoyspurs styyed |
-ppey ‘soyeys yoriq Geog 1 00S
9uoSpuvs
Avis YM aeys Oe “3 C00'z
(oryyedspyay
ud}JO) oUOJSpuRS os1V0D “zy COS
panuyuoj—OISSVIXL
W01499S
BYSLTY ‘SOLIS VIIQ ‘SoIag UNTO
BYSLLY ‘SOG YNUYAOF]
BYSLLY ‘SOIG O[[Ips0 J,
COE dt TEASE)
‘UOI}BULIO, = JUaXnyeg
suey
BYSeTY ‘Saag youyeN
BYSLLY ‘SIIIG ¥}}09-V1I9 T,
VYSELY ‘SOLIIG VJUIMYS
“RA SUIS
[vod puowyory ‘dno soyryor J,
UOISIY Pu UOTJLUIOT
426
panuy
“od—II UTEV.L
427
CLASSIFICATION OF ARKOSE DEPOSITS
Surppeq
-SSOID. yonu «yy = =pue
peppeq Ajury} SI UWoOneUWIO.T
SNOIsdBUOGIeS Spaq 9} [TV
suozii0y OM}
ye sjissoy jurjqg ‘worry
-17P1S 9]}}1] pue 19}9eIeY UT
UOI}LIIVA 9]}}I]T SMOYS VsOyIV
souvived
-de ur o1jtuvis yred ut ssoyry
ut Avis-ystnjq
IOTOO
‘QUO]SpuUvS
0JUI SuIpeis owos ‘souvIved
-dv Ul o1y1UvIS 9UIOS—SIDAP]
quUsIoyIp Ut
I]qeueVaA IsoyIy
9S0Z}1BN0)
dPIOIP Z31eNC)
ISOYIY
survas
jeoo yWM ‘97eIIWO]S
-u0d pur ‘ayeys ‘au0}Spues
spoq [evo pur oyeys
YJIM soy puv sUoJspursg
aseq oy} 32
d}VIIWIO[SUOD IO SOE
YjIM ouojspues ‘soyeys
snosovuoqivs ‘asoyay
IsOyIV
pue ‘soyeys snosveu0q
-Iea ‘guojspuvs oul
puv 9siv09 ‘9}e1OWIO;sU0D
ANHOOSTIO GNV ANHOO
asoyIe
ySOUL UL UeY} JoYsory reds
-P]ey fx1yeu ou YIM. z}1enb
pue siedspyej jo sures repn3
-ue ‘souvivedde ur o1y1uRI38
‘poureis-wmnipoul
‘ABI3-VYSVT
a}1OIpoursy
d}PIOWIO[SS ITULITOA,
ISOYIV IAISS IA
9u0}s
-purs puv oq]]Is1e poy
auo}spues dy} edspjo,T
9} PIOUIO[SUOD
auojspurs
oryyedspyay use13 0} Avid)
9VIDULO[SUOD 9SIVOD
au0js
-puvs o1yyedspjey use14
oy
d}LIOWIO[BUOD VSIvOD
SOSUZ] O}T[Id1e
rq YM suo}Spurs
o1yyedspyey ude18 07 AvIn
a}IT[Is1eV Yyoejq 07 AeriH
"yy O0S'S
*7J C00'S
—o00S‘f
"JJ OOOO
Ay C29)
“YJ OO1‘T
“YJ OO
"yy O0S‘T
"yy 002
“yy 0oS‘E
"JJ COf
"J OOb'T
“yy oor‘
"}¥ OOO'f
VYSLTY ‘UOLVULIO LeU sy
UO}SUTYSE
‘punog josng ‘uonjeuUio,, josng
UO}SUTYSe A
‘AQT[VA CUTYVA “UOIZVULIO YURMS
Oa
‘xTUs0Yg ‘UOTIVULIO IOART 971993T
10) tel
‘UdIUIOZOFT “I ‘osoye uoqyesheg
DONALD C. BARTON
428
ISOYIV UPTUOPIIIOT, 0} ILTLWUTS
qnoysnoiy}
wiaojytun AIZA SI 9SOYIe IY,
quasaid Ayjeuorse990 squid
doipurel puv = sajue yer
Ppeppeq-sso1a sARMR JSOUITe
pure poappeq A]PAIsseU VsOyIY
uornedar snouojouout
Ul d1B SYDOI yUdIOyIp IY,
zyienb pur zedspyay
|YselJ JO SUIvIS PpapuUNoOI-]jaM
|Ajoye1opour §=0}—s AR[NSueqns
XTI}VU OU YIM zyrenb
pue aedspjey ysory Airey
jo suleis popunol-jaMm 0}
/pepunos Aja}e19pour Jo pasod
-woo ‘gouvivedde ut o1y1uPIs
(ssorsajddy) osoyie soddq
SouTT[eySAID Uva xPIY
aseq 7® ssoyIe
O}JUL SUIpeis 9UO0}SpUues
NVIwaWvo
ayueiry
ISOYLY
d}LIOULO[SUOD YIM
pue oyeys uMOIq YIM
ay1zyVNb MoTPA 10 JT
9}eIOWIO][SUO0I pur
‘aqyizqyrenb ‘e1s901q YIM
JUOJSPURS PUL ISOYIV poy
SSIOUS UPISIMIT
asoyie
yoq pue ‘Avis ‘aAys uy
aseq Je BIII0Iq
ayeys yep YIM ou0js
-pnul puv 9uoyspurs poy
sayeys
poet d121 YIM VSOIe pdr
soyeys yep ‘ssvy pur
auoyspurs Avis puR pdx
NVIadnvo-dad
adOdna
a} eIOWIO[S
-uod pue ‘asoyie ‘[Roo
YIM 9UOSpues puP aeYS
panuyuo) —ANHOIOOITO AGNV ANAOOW
"yy C00'S <
“yy 007‘
"yy 008
"yy 000'R
—000'S
“yy CooL
—000'£
"yy 0OS‘z
PIAPUIPURIS
puryjurunosuy ‘ueruy0f
ARMION ‘oyusvieds
purp}oos ‘ouospuvs uUPIUOpLO y,
uoise1 Avg Jo][O1]U0_
SYIPWIIY
asOylY JO JojovIeyy)
wo1y295
UOIsayY PUP UOTJRWIO TF
panuyuoj—{y ATAVL
429
CLASSIFICATION OF ARKOSE DEPOSITS
ISOYIL
UI SUIeUel yuR{d poztuoqgie)
UOWWOI SUIPPIq-sso1d Vs1vOD
QSOFIL 9G 0} Wes
Pjnom suoyspuesS pay PIO
IaMOT 943 JO soseyd [eIaAIS
S[ISSO]
QUIIVU YIM Spoq po}eIossy
‘yspIy} “yy S-€ spoq ul ssoyIy
uaA9 SUIPpeg
SNOIIEUOILS ‘IAISSPUL
‘QUIf SOWITJIUIOS ‘9STVOD U9}JO
‘gouvivedde ul dIyIURIS BsOyIYy
ssoyxIv puv 9}v][SsS Apues
SoInsvoul [VOD JO oseq
[Zevw pur ajeys pur
JUO}SPUYS YSIPpat ‘9soylV
OTTTSTV
ISOyIY
OUTST YR
adUOJSpuvs
ARID
ISOYLY
Avo Apues o}IYM pue poy
SSIOUL)
ISOYI ISIVOD
au0ys
-pures snosovoIu UuMOIg
auo}spurs
pue jroo YM oss0xI1y
Surpedeid oy} 0} APIS YONUI UISeq [[eUIS
ssfous pur oyIUPRIN
d}PIOUIO[SUOD pur ‘ayeys
‘jeoo ‘asoyle pappoqiszUy
SNOWAATINOGAVO
ysory redspja,q
pei 0} yurd ‘10jo9
IIJLIOWIO[SUOI IUIOS
‘gsouvivodde ul o1ytUeIs UIOS
pepunod Ayjensed sureis zz1eN0)
ISOYIV-BYIU 9}IOIIG
9} VIOUIO[SUOD UTYY
‘guojspues pue dssoxIy
Souo}SpuRS PUL SoTeYS
NVINOAGG
"yy 06
“Vy Of
"yy OOf
"JJ CO£-O1
UISEG [VOD J9ZUOYLY-OUpryy
aSIIGISUISOTY
SUOT}VULIOT VUlRY pur neuneig
a“
UISeg [VOD Uss[axy
uopeg ‘xpospporosusyor,
uopeg ‘neusdg
uIseg YORqs[yo1yUTFY
uepeg ‘uapeg-uopeg
uopeg ‘uoydneysiog
UIeYIg yaIy ‘aUO}spuRS Poy PIO
SOUISIP [aya pur
souusply ‘UOT}VUIO,, UeIUUIpey
DONALD C. BARTON
430
UOWIUOD SUIPpaq
-SSOID ‘peppeq = ATYysnoxy
SUIppoq-sso19
yonut ‘fpappoq Ayrepnsory
Aasiaf MaN pue ‘x10 XK
MAIN ‘s}jJasnyoesseypy JO oIs
SULIT, JO oSOYIV 0} ALTIUS A19 A,
uoWOD ~SuIppoq
-sso1o ‘yporyy “4p © ATYysnor
speq ‘ysnor uoNPoyeys
ysodap v}jap B aq 0} JYySnoy Ty,
asoyle oy}
UL suTeUOI yuRTd paztuoqieg
9u0}s
ou] puv gfeys Avis
dIPI YIM 9} R.1OUIO[SUOD
pasoduioo [pu ‘ayeys ‘asoxre ‘au0}s
-9p Mou sedspyey ‘asozjien() |-purs o1yzedspyey Yystppory
STAONAOAITLON
souvived
-dv ur o1jmueis f10;09 ut Ain
ystXvis 10 ystnyq
tojoo ‘faouvivedde ur oy1uURIy
quad iad oz ynoqe xtyeu
‘rejnsueqns sureis ‘asozjz1vN()
SoINsvou [VOD UT
a[vys puv 9UO}SpuURS PdY
ayeys Avan
auojspues o1y}edspyey
puv ‘aeys ‘asoyre YSIPpIy
jee Ra Be
a[eys pue suojspurs AeIny
9} LIIWOTSUOI 9S1BOD
YIM 9UOspuRSs pue s[vYS
9UO}SpULS PIUTeIS-dUy
‘MOT[PA pu aeYys Ywrypq
auoyspurs o1y}ed
-Sppy pure o}RIBWIO[SUOD
SUOT}VIII PUL IOJOVIvVYO TLITWIS JO ISOYIV
xL}eu su ut reds
-PppPy} pezruyory yonut pue
zyienb «sures = re_nSueqns
soouvivodde ur o1y1uvs13 Javed uy
sstoury
ASOYI YSIAvID
eee Ope eS 5.32
9} LIIWIO][SUOD VSIvOD "1 9
9} eIDULOTSUOD
ou YIM ssoyre YSstAviy “VJ O1Z
panunuoy—SNOUATINOPAVO
Auruliory “Jouysiq, ayeN pure
Ievg ‘spog JaAajoy, J, pue sJopasng
purysug “ploy pure urginy FIP
pursuy ‘pp [vog s11ysy10 x
QOUTAOI
DUTY ‘IOTI9M7}O ‘Snossjruoqiey
Joddy pue sopuasajoy JoMO'T
“STA
sossoA “AITIOM, pue Yorquoply
“S}IN SosSOA “YOeR'T
SyIRUII x
IsOYIY JO 1ojvIvyO
u01q99g
UOLsay pPue UOT]UIO.T
Pannyyod— Th w Tav.L
431
CLASSIFICATION OF ARKOSE DEPOSITS
quojspurs ay} jo osvyd
yeooy] B AyUO SI gSsOyIV oy,
yuosoaid s]issoy quLTg
qyuosoid
Ajqissod sojqqed = peaqjaoe
“QAISSVUL
‘UdAd JOYJVI = WOTPBOYT}LI}S
QTPYs oY} Ul suorssoidurt jury
Agsiof MON pur ‘YOK MON
‘qnoTJDIUUOD ‘s}Josnyoesse
JO OSISSVIIT, 94} JO soy
0} IepTUMIs ATOA AT[VIISOT[OYIWT
Ssurppeq
-SSOID IVI YUM ‘sIoAVT
UdAD ‘QAISSVUL UL SI ISOYIV
9S0Z}.1UNQ)
souvived
-de ut omiueis ArvA yied uy
pozrurjory Aja}e[du109
mou iavdsppoy} por ‘asozj1enQ)
g0ue
-Ivoddv ul o1y1UeIs pue ss1v0D
pesodwuiosep Ajojo,d
-ul0d Mou Iedspfay ‘fesozjreN)
BIIIIIG
pure ‘o}e10UL0;sU0D
‘soyeys ‘osoyre YSIpparyy
speq yorq
Ud] 10 Ystyos ‘oyuUvIs
9} VIIULO[SUOD YTM ISOYIV
greys YIM osoyre Avi
SUOT}L[VIIOJUL
asOYIV YIM g[eys oding
9uo}Sspues
pur ‘osoyre ‘9}e1VWO[SUOD
souo}s
YSIPp9ad
oq TUL
-O]Op pur osoyIe YIM
guoyspues s1yyedsppaT
gjeys pur
ssoyie Avis SuryeUIoy
9d} V.IOULO[S
-uod pur ‘auojyspues
‘so[evys YIVp YIM ssoyIy
oyURID)
ayeys
poyesouvA pure 9s9soyIy
a[BYSs poyeSoIva pue Yyorlq_
ISOYIV YIM 9} LIOWIO[S
-U0d aTvYS ‘VUO}SpURS PIY
oyIURID
syn} pue osoyiy
-pniu ‘sayeus
1
syny
[zew pur ‘au0js
-pnur ‘auoyspuvs ‘oyeys
pol YUM ss0yxIe por
“YF OOO
-obS
“VW C9
34 09
“yy 06
“JJ COI
‘UISeg
“S}JAL SOBSOA ‘Spoq JoyDeqTYyosy
SJ], SossOA ‘spoq Yyoequorty,
solo] Joryg ‘wreyydgyos
}S010,J
yprpg ‘sioquivry9s ‘spaq yorqoy]
ysolo,y yorpg_ ‘neusddg
Auvulloy ‘uspeg-uopeg
Auvulioy ‘s1oqjeploy
AUBULIO)
ZUR, ‘spaq JaAoOUL,
DONALD C. BARTON
432
XLIJUI SNOddETIBIV
Sutppaq-sso1o auros = |ssay «IO 910W YM AT[ensn
St o19y} Ajarer {spaq oats |‘sourreodde ut = orjURIZ
-SPUI SSd] JO 91OU UI SI asOyIY [AIBA Jed ul ‘AUG 0} asIROD
a}UPIDy
(Ayuo urseq
24} Jo aed wroyznos
ul 9soyIe jeseq pur
auojsouy ~‘sAep> Apues)
s}113 ‘spew
pue soauojspurs ‘sosoyly
JUOJSOUT] PUL SLIP]
ASOMAV AUVILAAL
a
syisodap a10ys aq 0} yoRIny
Aq _ pesoddns oie ‘asoyie xl}eW YON yNoYyyIM
ay} JO Ayeiadsa ‘sjisodap ayy, |10 AIM 9sozjenb Aaa ATISOPL
asoyle
pur ‘jrew ‘Arp ‘au0jspues
yew
pue ‘Avo ysippel ‘au0js
-suT] ‘asOyIe dIITULO[O
oryyeds
-PpPy Ayyeooy = ‘auoyspues “qj 09
ose pay yy OS1
AYTUIIA pur Ule}SyxIeY 1B
a7eurye[eg 9} UI asoyIe
OJUL Suipeis ‘auojspues “4 009
asoyie Surpadeid ay JO yuayeAtnba ayy Ayqissod ‘asoyre IepIUIS JEYMIWIOG
syoei} atdor YIM
do} 94} pieMo} speq afeys |poureis-ouy ‘surpunor yonut
UIYy} YIM ‘aseq oy} 3e Speq BZuLmoys sureiZs yuanzsuOos
UIAI ‘JAISSBU UI VSOYIV IOMOT ‘payflopIs A[IAvaY pu 9SOZ}IENC)
XEJeUL_PayLoryis
ayUeIL)
SuOI}e[eO
-Iajyut AVARPD YIM VsOyIy “J 06
pew pur ssoyxiy 3 Of
uinsdAS pue sU0}SoWII'T
OISSVIAL
ayueis Sursjiopun
94} WOIJ psatiep jOU SI yng
‘aseyd yeseq & SI asoyIe ayy, [xLyew ouy YIM ‘AvIZ ‘asivO_ |
aque
BID991q
pue ‘asoyie ‘au0jspues
‘gjeys ‘a}eIIWIO;ZU0d
panuyuo)j—_SAGNADaITLOa
syIeUlaYy aSOxIY JO JoyovIeYyD
w01999S
panuyuwoy—iIl TTaVL
aouRiy ‘ouseuT
spoq uPIstIouuRs
speg uvidure}s
eIUOIUPL
spoq rodnay jung
SRee eet ct
suoa’yT Ieou ‘Assay
ayspeply ‘sreuaqny
uoli] re9U ‘AT]TUUD
aouely ‘OLMISIP UPAIOSY
yso10,q BIsuLINy J,
uolgay pur uor}eUIIO.J
433
CLASSIFICATION OF ARKOSE DEPOSITS
o}ULIS 94}
OUI Sopeis ssOyIe IY} AT[RIO'T
asOyIe
quosoider 0} Ajqissod wey
“PIO Aq paararaq st sstous oy,
souvivodde ur dIy1UPID
ays pur Z}1eNb jo x1yVeU
‘souvivodde ut d1y1uPIs ‘osre0*
ayuPIS SulAjIopun
oy} 0} oduervedde ul Ir]
-IWIS AI9A puv OT}TURIS syed UT
.
pesoydiouejyour yonzy
URI
9} LIDULO[SUOD
S}Is
o1qyedspjoy pure osoyiy
UO}SOWIN'T
VOTSAV
ISOYIV IWOS YIM ATQIS
-sod ‘so}v1aWOp, suo. pue
SauO}SpURS SNODUASO19}9F]
aque
SOIL PUL 9}1Z}1eN()
sayeys sno
-OVUOGIVS PUL JUOISOWTT
ouIZ
-yzenb pur ‘ystyos ‘sstour)
ISOWIL
YM —-941z} RNC)
SSIoUS ULYS-IP, J,
aSOYLy
SoPIUIWUeS J
Be lec
ayuedyy
d}eIOULO[SUOD pue a
ayeIOULO[S +4 OST
-U09 PUP 9UO}SpURS as1vOD |
yeseq
(aeEqureD) OTL
VISV
wy} 0} JuaTeAinbs ATqeqord pue Ssurpaseid oy} 07 reprams sjisodep ssoy1y
AUOTOD
adey ‘yoox] your ‘sattag osuo)
Auojog odey
‘ATY salyepy ‘soag osuo0d
snpuy toddyQ ‘spoq sus007%y
VIPU] ‘UOT}VUIOY IeMeg
eipuy ‘dnorry oArry
PIPUT ‘UOTJVULIO IVMTY
WI9}ShG 12, I-NA\
DUTAOLY IZ [Suv A
OURI
Z910.J JO ulseg
UOIquIO'T JO Use
DONALD C. BARTON
434
IOJUM 9Y} JO 1jOU dy} 0} JWOD SPY BOLOUY YINOG UL JO VITPAYSNY UL
oyueid ayy 07UL
soprid ssoyie ayy ‘asoyie
ayy jo yard szoddn ut yuososd
Ajqissod = uoreoyryesys jure y
SHIVUIY
VOIMAWNVY HLNOS GNV VITIVALSNV
pies)
ISOLY
dVRIDULO[JU0D pur
souravodde ut o1ytueid AIDA aUOJSpuRS snNoddeT[1y
xXUyeuL SISIYIS DUI[eISAI
auy YIM ssozjienb ‘ysippory ISOYI PUP OYOBMNIL)
S}SIYOS OUI][eISAI)
ISOALY
souojspurs
snoaieo[v9 pur sareys
ysippet pure ysrudasry
S19AR] DITWO[Op pur
aUOTSPURS YSIIYM ‘osoyry
sures spaq Ayqqad
iepndue yy ys Ysippay [pur Addvpo YIM ssoyLy
OUP)
AVPIDULO[SJUOD puv asOyLy
Aes pur oyIZ41eNC)
Ssstaury
DUOSpURS PUP oyeYsS
YIM 9VBIDULO[SUO0D IISOYLY
JUOJSPURS PUR 9[PYs YLVC]
panuyuoy—VOTAAV
AIYWO IDOYAV JO JUNOIOV ON
JUOPSPULS UPICN NT
wOLYY Sey YSN Gopny oye]
OAUOD) YOUIL ST
‘URIUOAX(T ~=pur = SNoOsayruOqan,
ysVoy ploy
Auopodg adey ‘satag jaoy yori
Auojog adeyg ‘sarsiag ysnsaMmnoryy
aBOYLY JO 1ayIvILY u01499g
panuyuoj—Il ATAVL
uoWsay pue UOIyeULIO
CLASSIFICATION OF ARKOSE DEPOSITS 435
A. ARKOSE DEPOSITS FORMED ENTIRELY UNDER RIGOROUS
CLIMATIC CONDITIONS
Feldspar showing merely slight decomposition.’ Argillaceous
material absent or present in minor amounts.’
1. Deposits formed in desert regions.—The deposits are massive,
homogeneous, and in some cases of very large size. In desert
regions, the disintegration takes place chiefly on outcrops directly
exposed and not protected, as in moist temperate regions, by a
mantle of vegetation. The débris of disintegration is easily
eroded and the processes of erosion and disintegration and deposi-
tion of the eroded, disintegrated material as arkose can therefore
take place contemporaneously, and can continue as long as the
desert conditions persist and as long as the granitic terrane remains
unburied. The size of an arkose deposit formed under such con-
ditions will therefore depend chiefly on the size of the terrane of
disintegration, the size of the basin of deposition, and the length
of time the desert conditions prevail. ‘The constancy of the condi-
tions during the period of formation should be marked by a massive-
ness and homogeneity of the deposits.
a) Terrestrial: In deserts, wind action prevails the greater part
of the time, but rare storms do occur and in the short space of their
existence do an immense amount of work. Deposits of arkose
formed in desert regions therefore are likely to be in part of eolian
and in part of aqueous origin. The arkose shows in part the
eolian characteristics of well-rounded sand grains, faceted pebbles,
local lag-gravels, dune stratification, etc., and in part the ordinary
characteristics of water action. In deposits of arkose forming in
arid mountain regions, the greater part of the transportation of
the disintegrated material may be by water action, during the rare
cloudbursts, and by the streaming of the débris down the hill slopes
under gravity. The constituent grains in this case are subangular,
and quartz and feldspar grains should be present in about the same
proportions as in the original granite or gneiss, since the amount of
t At the time of formation of the arkose. Subsequent exposure may produce
complete decomposition.
2 The possibility of the presence of exotic material brought in by a river whose
headwaters lie in a temperate or tropical region should not be forgotten.
436 DONALD C. BARTON
transportation undergone should not be sufficient to cause marked
comminution and loss of the feldspar. The deposits as a whole
should be rather massive, but with cut-and-fill stratification rather
common, and with considerable intercalation of coarse block débris
toward the sides of the valleys.
An example of this type of deposit is found in the Applecross
group of the Torridonian sandstone, a pre-Cambrian formation
extensively developed in the Northwest Highlands of Scotland.
The ideal section of the Torridonian sandstone is given by the
Geological Survey* as shown in Table III. The Applecross group
TABLE III
Groups Thickness Composition Chief Occurrence
3. Aultbea....| 3,000-4,000 ft.| Sandstone, flags, dark and black; Loch Ewe and
shales, and calcareous bands) Loch Broom
passing down into chocolate and
red sandstones, and gray micace-
ous flags with parting of gray and
green shale
2. Applecross..} 5,000-8,000 ft.| Chocolate and red arkose with peb-| Cape Wrath to
bles of quartzite, quartz-schist| Skye
(felsite, jasper, etc.), and occa-
sional red and chocolate shales
2. Diabaig....} 500 ft. in Gair-| At top, fine red sandstone with red} Assynt to Skye
loch; 7,000/ mudstone and gray shale; at
ft. in Skye base,’ coarse breccia of Lewisian
gneiss. In Skye, gray and buff
arkose in great thickness
is a formation composed of massive arkose of very uniform character
(Fig. 3), marked off by thin intercalations of fine quartzitic and shaly
sandstone into persistent layers of rather uniform thickness—in each
case three, six, or ten feet or so. Although extremely massive in
texture, the arkose shows most irregular stratification and almost
invariably is strongly cross-bedded. Walther reports cross-bedding
indicative of dune formation, and faceted pebbles. The lithologic
character of the arkose may be seen from the accompanying photomi-
crograph. In the finer-grained phases, quartz composes a slightly
greater proportion of the whole than in this medium-grained phase
(quartz about 60 per cent and feldspar 4o per cent), and the grains
«B. N. Peach, J. Horne, and others, ‘‘The Geologic Structure of the Northwest
Highlands of Scotland,” Mem. Geol. Surv. Great Britain, 1907.
CLASSIFICATION OF ARKOSE DEPOSITS 437
show a slightly greater degree of rounding. It is notable that the
predominant feldspar of the arkose, microcline, does not occur in
the underlying terrane. Where the arkose rests directly on the
mountainous topography of the underlying terrane, the arkose
basally becomes a coarse breccia. One of the most striking features
of this formation, with the exception of this basal portion, is its
uniformity throughout its great thickness.
To this type of arkose
deposit should be referred
the following:
The Torridonian Arkose,
pre-Cambrian of Scotland.
Arkose of the Sparagmite
formation, pre-Cambrian of
Scandinavia
Lower Old Red Sand-
stone, Scotland (in part)
Paysaten Arkose, Creta-
ceous, British Columbia-—
Washington
b) Marine: If marine
conditions prevail adja-
Fic. 3.—Photomicrograph of Terridonian
cent to a granitic terrane arkose, Applecross, Scotland, showing the lack of
in a desert region, marine matrix in a desert arkose. The rounding of the
grains is rather obscured by secondary growth of
the grains. Magnification, 15 diameters.
arkose may form, having
in part the characteristics
of an eolian arkose. Some of the constituent grains in this case
should show the rounded outlines of eolian sand grains. The
deposits as a whole, however, should show the structure and
stratification of marine sediments. To this type of deposit should
be referred the arkose that is now forming along the east shore of
the Gulf of California. :
2. High-altitude deposits—Local deposits, of small size and
extent. The conditions of high altitude, according to Oldham and
others, are peculiarly favorable to disintegration. Erosion of the
disintegrated material takes place rapidly, with rapid deposition
of it in many cases as arkose in local catchment basins of the
intra-mountain valleys. As such a region is subject to general
438 -» DONALD C. BARTON
degradation in the course of time, the deposits must be temporary in
character, and usually of recent geologic age. ‘They may be wholly
or in part lacustrine, fluviatile, alluvial (cone or fan), landslide, or
fluvioglacial. The stratification should be rather irregular, and
the constituent grains should be angular to subangular.
To this type of deposit should be referred possibly some of the
deposits of the Upper Indus Valley, although from the descriptions
of the deposits it is not
quite clear whether they
are really arkosic or not.
3. Deposits of cold
(high-latitude, subglacial)
climate.—In the high lati-
tudes, the effects of dis-
integration are not pro-
nounced, or at least they
are, not noted in the lit-
erature. ‘‘Disintegra-
tion’ is reported many
times, but in most cases
1G. 4.—Photomicrograph of Pondville (Mass.) it is clearly’ block disin-
arkose, an arkose formed under moist temperate tegration that is meant,
conditions, showing the quartz and feldspar grains and in no case has the
in a fine-grained matrix of quartz and argillaceous :
material. Magnification, 15 diameters. writer been able to make
it out clearly to be granu-
lar disintegration. ‘That the effects of the latter are not notice-
able may be due in large part to the relatively recent glacial
erosion of the products of the preglacial disintegration, or, in
regions of considerable relief, it may be due in part to excessive
block disintegration and erosion. As the temperature range is
often great, and the lower part includes the critical point of
freezing, and as, furthermore, hydration can take place at the
surface during the summer and, in regions not too far north,
at all times below the level of freezing, there would seem to
be no theoretical reason why granular disintegration should not
take place. Granitic and gneissic blocks exposed on the surface
of glaciers in many cases show noticeable disintegration, although
CLASSIFICATION OF ARKOSE DEPOSITS 439
the amount that takes place in this manner is slight. If disintegra-
tion takes place, the conditions would seem favorable to the erosion
of the disintegrated material and its deposition in arkose deposits
of small or moderate size, probably in association with glacial or
fluvioglacial beds. ‘To this type of deposit may possibly be referred
some of the pre-Cambrian arkose of Canada.
B. DEPOSITS FORMED DIRECTLY OR INDIRECTLY THROUGH THE
EFFECTS OF MOIST AND USUALLY TEMPERATURE CONDITIONS
Deposits of small or moderate size; the arkose commonly with
a matrix of fine-grained argillaceous material and usually associated
with argillaceous beds; feldspars commonly showing a moderate
amount of decomposition (Fig. 4).
In the present regions of moist temperate climate, especially
where the topography is in a mature or old-age stage of develop-
ment, there is almost universally present a very considerable
accumulation of disintegrated material which is available as a
source of material for the formation of arkose. The following
section, from the vicinity of Autun, France, in its essential features
is characteristic of such regions as the granite terranes of Morvan,
the Plateau Central, and Forez, France; the Vosges Mountains,
the Odenwald, and the Thiiringerwald, Germany; Dartmoor,
England; the Piedmont belt and the Pike’s Peak region, United
States.
iLO PR anon sae Mantle of vegetation; surface soil and subsoil of
gritty brown clay with quartz and feldspar grains
6ft.........Granitic sand and gravel, stained with limonite; feld-
spar showing considerable decomposition toward the
surface, the amount decreasing with depth
Dy on Granite more or less fresh on superficial examination,
but crumbling under light blows of the hammer;
depth difficult to estimate; fresh granite
The relative and absolute proportions of these zones vary greatly.
The maximum depth to which disintegration was observed by the
writer to have extended was 4o feet, at Royat (Puy-de-Déme),
France, and at Hohkénigsburg, Vosges Mountains. On Dartmoor
and in the Piedmont belt decomposition is more in evidence than
in France and, in the Piedmont belt especially, the zone of soil and
440 DONALD C. BARTON
subsoil is much larger in proportion to the zone of disintegrated
material. The rate of disintegration under the conditions of a moist
temperate climate seems to be rather slow—in New England there
has been since the Glacial Period disintegration sufficient barely
to efface the glacial striae and polish on granitic and gneissic
ledges—and the very considerable amounts of disintegrated material
generally found in those regions are the result of slow accumula-
tion under the protection of the mantle of vegetation. General
erosion of this disintegrated material and its subsequent deposition
as arkose can take place only when the mantle of vegetation is
critically weakened or destroyed. When this has once happened
and the mantle of disintegrated material has been swept away, a
long time must elapse before considerable amounts of the disin-
tegrated material can again accumulate. The arkose deposits
formed from the accumulated débris of disintegration in a moist
temperate climate will therefore be of small or moderate size. As
the mantle of soil and completely decomposed rock is eroded at
the same time as the mantle of disintegrated material, the arkose
is commonly associated with mudstones and shales, and, as
the disintegration is accompanied by considerable decomposition,
the arkose itself is likely to contain much argillaceous material
and to have feldspars showing noticeable decomposition. Since
stream transportation of débris results in the rather rapid elimina-
tion of the feldspars, the arkose is likely to grade into quartzite.
The causes which might critically weaken or overcome the
mantle of vegetation and result in the erosion of the accumulated
products of disintegration are: introduction of arid or semi-arid
conditions, introduction of subglacial or glacial conditions, a marked
increase of rainfall, a marine transgression, deforestation by forest
fire, and marked upwarping. A marked change of climatic con-
ditions toward aridity in a region previously of moist temperate
climate would necessarily result in a marked diminution of the
vegetation and in the exposure of the underlying disintegrated
material to erosion during the occasional storms. Glacial condi-
tions might result either in the erosion of the disintegrated material
by the ice itself or in the exposure of the disintegrated material
to erosion through the destruction of the vegetation of the temperate
CLASSIFICATION OF ARKOSE DEPOSITS 441
conditions without the introduction of an arctic flora sufficiently
luxuriant to form anew the protective mantle of vegetation. A
marked increase of the rainfall, it was suggested by Shaler, might
be such that the streams would be competent to waste generally
the land surface. A marine transgression would necessarily result
in the working over of the materials of the regolith, irrespective of
the luxuriance of the mantle of vegetation, and might easily result
in the deposition of arkose. Forest fires are not uncommonly due
to lightning and often are effective agents of deforestation. It
would seem possible that a period of heavy rains following a
severe forest fire might result in the géneral erosion of the mantle
of disintegration. Upwarping of considerable amount would result
in an increase of the stream gradients, in an increase or decrease
of the rainfall, and in the lowering of the mean temperature. The
total effect might possibly be conditions favorable to the general
erosion of the mantle of disintegration. A very special cause is
to be found in volcanic activity of the explosive type, which not
uncommonly results in deforestation and desolation in limited local
area. Of this type of deposit, in which the arkose should be asso-
ciated with tuffs, there is at least one example, the Rotliegendes
arkose north of Heidelberg, Germany.
In regions of youthful topography and considerable relief in a
moist temperate climate, there would seem to be no reason why
disintegration should not take place. That it is not seriously in
evidence is probably due to the fact that it is masked by block dis-
integration and by rapid erosion. If it does take place, the débris
that can be eroded at one time is of small amount and is lost through
decomposition of the feldspars or through intermixture with the
heterogeneous stream-borne sediment.
In tropical regions, decomposition commonly prevails over
disintegration, but in two localities disintegration is reported as
occurring with but slight accompanying decomposition. The débris
in these cases, if eroded under normal conditions, would probably
be lost through decomposition, but if eroded under the conditions of
a marine transgression, or under the conditions of aridity, there
would seem to be a strong possibility that a deposit of arkose might
be formed. Except by means of a contained fauna or flora, such
442 DONALD C. BARTON
deposits would probably be indistinguishable from the correspond-
ing types of deposits of the temperate zone. No deposits have been
recognized to be of this type.
. Terrestrial—(a) Deposits laid damn under semi-arid condi-
es Arkose reddish, composed of subangular iron-stained grains
of quartz and partially decomposed. feldspar deeply in an iron-
stained matrix of fine-grained quartz and of argillaceous material.
When the moist temperate conditions give way to those of
aridity, the mantle of vegetation, weakened by the change, is
no longer able to protect the accumulated products of decomposi-
tion and disintegration, and during the occasional violent storms
they are quickly eroded, to be deposited with rapidity usually in
the near-by valleys and catchment basins. Owing to deposition
from torrential streams, the materials of the mantle of disintegrated
material are laid down in coarsely stratified banks and lenses of
arkose, showing much foreset and cut-and-fill cross-bedding. The
soil and mantle of completely decomposed rock are deposited,
partially sorted, as cross-bedded, argillaceous sandstones and as
more finely and evenly stratified gritty mudstones. As the
temporary lakes dry up, these mud beds become sun-baked and
glazed and cracked and may receive raindrop prints. Under the
conditions of alternate wetness and dryness, there should be almost
complete decomposition of organic matter and oxidation of the
iron.
Deposits of this type are not rare, and a good example may be
found in the Sugarloaf arkose of the Connecticut River Triassic.
The formation occurs in what was possibly a Triassic basin, and
consists essentially of an unordered alternation and repetition of
gritty, argillaceous sandstones, conglomerates, arkose, and sandy
and calcareous mudstones. There is a coarse, general stratification
whose dip initially was apparently low. In the beds of mudstone,
even, fine stratification is the rule, but cut-and-fill bedding is found
in a few places. The coarser strata are strongly cross-bedded,
mostly with the foreset type of bedding. Cut-and-fill bedding,
however, is common. The mudstones show mud-cracks, raindrop
prints, glazed surfaces, and reptile footprints. The arkose is
found in banks and lenses, chiefly at or near the base, but also at
CLASSIFICATION OF ARKOSE DEPOSITS 443
numerous higher horizons. It is.composed of subangular grains
of quartz and subangular grains and pebbles of feldspar in a fine-
grained matrix of argillaceous material. The color of the whole
formation is deep red, due to a heavy stain of ferriciron. Fossils are
rare in the formation.
The following deposits are apparently of this type:
Arkose of the Amnicon formation, pre-Cambrian, Wisconsin
Sugarloaf arkose (Triassic), Connecticut River area, Massachusetts and
Connecticut
Stockton arkose (Triassic), New York, New Jersey, Pennsylvania
Arkose of the Upper Carboniferous, Ottweiler, Rhine Province, Germany
Arkose of the Lower Rotliegendes, Rhine Province, Germany
Arkose of the Rotliegendes, Mainz Basin, Vosges Mountains and Black
Forest, Germany
Arkose of the Old Red Sandstone, England
Arkose of the Cutler formation, Permian, Colorado( ?)*
Arkose of the Fountain and Lower Wyoming formations (Permian),
Colorado(?)!
(b) Deposits laid down under moist, chiefly temperate, condi-
tions of climate: Arkose grayish, composed of subangular grains
of quartz and of considerably decomposed feldspar in a matrix
of fine-grained quartz and argillaceous material, in most cases
carbonaceous, and in some cases carrying plant fossils; the arkose
commonly associated with coal deposits.
The causes of a general erosion of the regolith in a region of
moist temperate climate are not completely evident. The sug-
gestion of the introduction of subglacial conditions as a possible
cause seems not well founded, since the several glacial epochs of the
Pleistocene do not seem to have caused a general erosion of the
regolith of the Piedmont belt to the south of the glaciated area.
It would seem reasonable to expect, furthermore, that the effect
of the change on the mantle of vegetation would be a replacement
of the temperate by arctic flora. The suggestion that a marked
increase in the amount of the rainfall might be a sufficient cause
would likewise seem not well founded, as an increase in the rainfall
characteristically results in more luxuriant vegetation, with a con-
sequent increase in the protective power of the mantle of vegetation.
* Commonly considered marine, but apparently very like the Newark beds of the
Connecticut River and the New York-New Jersey Triassi ‘»reas.
444 DONALD C. BARTON
Forest fires are another possible cause. They are very commonly
due to natural causes and often are effective agents of deforestation.
It would seem possible that a period of heavy rains following a
severe forest fire might easily result in the general erosion of the
regolith. Upwarping of considerable amount, with the consequent
increase of stream gradients and lowering of the mean temperature,
if associated with decrease in the amount of the rainfall, might
possibly result in the general erosion of the regolith.
While these causes are thus in doubt, the fact of the formation
of deposits under these general conditions seems to be indubitable.
There is a characteristic type of arkose deposit which is usually
associated with carboniferous beds or coal, which is itself carbona-
ceous or may even carry carbonized plant remains, and which there-
fore must have formed under moist climatic conditions. As the
feldspar shows much decomposition, as there is an argillaceous
matrix, and as the quartz and feldspar grains are distinctly angular
to subangular, the constituent materials of the arkose would seem
to have been derived from the débris of disintegration under moist
temperate conditions. The arkose, commonly in part, is coarse
and granitic in appearance and seems not to have been transported
far from the point of origin of its constituent material, and in part
usually is finer and less feldspathic, and seems to have been trans-
ported for a greater distance. Besides being associated with coal
beds, the arkose is associated with conglomerates, impure sand-
stones, and silty mudstones. Cross-bedding is common, and many
of the beds seem to be the result of rather rapid deposition. The
color of this type of arkose is gray.
As an example of this type of deposit, there may be taken the
arkose of the Richmond (Triassic) Coal Basin in Virginia. The
lower portion of the section in the basin is as follows:
Productive Coal Measures.....500 ft. Interstratified beds of bituminous
coal, black shale, feldspathic and
micaceous sandstones
Lower Barren Beds.........0-300 ft. Sandstones and shales under the
coal beds, often with arkose
Boscabel Bowlder Beds....... o-so ft. Local deposits of bowlders of gneiss
and granite
tN. S. Shaler and J. B. Woodworth, U.S.G.S. Nineteenth Ann. Rept., Part II
(1897-98), pp. 423-26.
CLASSIFICATION OF ARKOSE DEPOSITS 445
The arkosic beds are best developed about the granitic masses of
the eastern margin, but reappear from horizon to horizon with
increasing marks of waterwear. ‘The arkose of the basal horizons
is granitic in appearance, and by the inexpert eye might not be
distinguished from the granite. The arkose is gray in color and
is composed of subangular grains of quartz and much decomposed
feldspar in an argillaceous matrix of small amount. The arkose of
the higher horizons is not so granitic in appearance, there is a
somewhat lower content of feldspar, and the quartz and feldspar
grains are slightly more rounded. Some of the associated shale
beds are carbonaceous, and locally there are small intercalations
in the arkose of carbonaceous silty material. .
To this type of deposit there should probably be referred:
The Carboniferous arkose of the Narragansett Basin, Rhode Island and
Massachusetts ‘
The arkose of the Rockwell formation (Mississippian), Meadow Branch
Mountains, West Virginia
The arkose of the Vosges Mountains, the Black Forest, and adjacent
parts of Bavaria
The arkose of the Coal Measures of the Yorkshire Coal Field, England
The arkose of the Coal Measures of the Flint, Rhutin, and Mold districts,
England
The arkose of the Richmond (Triassic) Coal Basin, Virginia
The arkose of the Corwin formation (Jurassic), Alaska
Comanchean arkose at the base of the Coastal Plain series, Maryland,
Virginia, North Carolina
The arkose of the Swauk formation (Tertiary), Washington
The arkose of the Puget formation (Tertiary), Washington.
The arkose (Early Tertiary) of the Matanuska and Controller Bay regions,
Alaska
c) Deposits formed under glacial conditions: If an ice sheet
advances over a granitic terrane in which there is a mantle of dis-
integration, it would seem possible for small amounts of this débris
locally to be preserved as arkose among the various glacial deposits.
In New England, there is in several localities deep preglacial dis-
integration, showing that the mantle of disintegration of the
Piedmont district probably extended in former times northward
over this area. Arkose is apparently lacking however, in the New
England glacial deposits. No example of this type of deposit is
known to the writer.
446 DONALD C. BARTON
2. Marine and lacustrine—(a) The basal member of a new,
transgressive marine series is commonly composed of the materials
of the former regolith. If the shore forces are not too violent in
their working over of the débris, the basal deposit in regions of
granitic rocks may be arkosic. The constituent grains show more
or less rounding. There may be present a small amount of argil-
laceous matrix. Through the elimination of the feldspar the arkose
may grade into quartzite. Arkose deposits of this type may grade
into deposits of the type discussed in (0).
To this type of deposit (a) there should be apparently referred:
Arkose of the Hotauto formation (pre-Cambrian), Shinumo Quad., Arizona.
The Cambrian arkose of Eastern United States (in large part)
The arkose (Silurian) of Littleton, New Hampshire (in part)
The arkose of the Igaliko formation (Devonian), Greenland
The arkose (Triassic) of the Morvan (in part), France
The arkose (Tertiary) of the Limagne (in part), France
(b) When erosion of the mantle of disintegration in a granitic
terrane adjacent to the sea or to a lake occurs, deposition of the
disintegrated material is likely to take place in the sea or lake with,
as a consequence, the formation of arkose. Near the shore the
arkose is in banks and lenses and is interstratified with beds com-
posed of the material from the soil and zone of decomposition and
of argillaceous material eliminated from the débris of disintegration.
The constituent grains of the arkose are subangular to poorly
rounded, the degree of rounding being greater in the more quartzose
beds. There may in some cases be a slight amount of argillaceous
matrix. Unless the feldspar is itself reddish, the arkose is
grayish in color. Although not necessarily basal, the arkose is
more likely to be near the base of the formation than not, since
the change of conditions which causes the erosion of the mantle
of disintegration is likely to mark the inauguration of a new period
of sedimentation. The arkose formed far from shore is less granitic
in appearance than that formed immediately at the shore, there is
considerable rounding and sizing of the constituent grains, and there
is elimination of much feldspar and argillaceous material. The
arkose in many cases grades into quartzite.
An example of this type of deposit is the Tertiary arkose of the
Limagne, France. During the Oligocene times the Limagne was
CLASSIFICATION OF ARKOSE DEPOSITS 447
first a brackish-water basin some thirty km. in width and later a
fresh-water lake lying then as now in the granite plateau of the
Plateau Central. The arkose is found chiefly near the base and is
found in banks alternating with greenish marl and in some cases
extending out a considerable distance from the edge of the basin.
Some of the arkose, especially that at Royat, is massive, coarse,
composed largely of good sized fragments of the coarse phenocrysts
of the underlying granite, and is extremely granitic in appearance.
The greater part of the arkose, however, is much finer, is more
quartzose, is composed of more-rounded grains, and grades into
quartzite. There is in some cases an argillaceous matrix, in some
cases a sericitic matrix, and, in some of the more quartzose phases,
there is very little matrix. There is a general even horizontal
stratification. Where cross-bedding is present in individual strata
it is usually of the simple foreset type.
To this type of deposit are probably to be referred:
Much of the pre-Cambrian arkose of Ontario
Arkose of the Congo Series, French Hoeck, Cape Colony
The Cambrian arkose, North Carolina-Tennessee
Fitch Hill arkose, Silurian, Littleton, New Hampshire
Haybes arkose and Weismes arkose (Devonian) Ardennes—Eifel District
Arkose of the Grés bigarrés and Grés vosgien (Triassic) of the Morvan
region, France
Dolomitic arkose (Keuper), Franconia and Thuringia
Arkose of the Blasensandstein and Coburgerbausandstein (Keuper),
eastern Palatinate
Lower Stampian-Sannoisian arkose (Oligocene), Limagne, Forez, and
Roannais basins, France
Much of the Jura—Cretaceous arkose of southwestern Alaska
Arkose of the Cutler formation (Permian), Colorado( ?)
Arkose of the Fountain and Lower Wyoming formations (Permian),
Colorado( ?)
C. UNTRANSPORTED OR SEDENTARY ARKOSE
Basal, unstratified deposits grading into the underlying granite.
When deposition begins in a district, the original regolith locally
may be buried before it has been eroded to any considerable extent.
It is thus possible for arkose to be formed without the usual inter-
mediate steps of erosion, transportation and deposition of the
448 DONALD C. BARTON
disintegrated material. The arkose is composed of the constituent
minerals of the granite or gneiss in essentially their original propor-
tions. Some of the silicates, especially the biotite, hornblende, and
plagioclase, are in many cases highly decomposed. Theiconstituent
grains are angular. The upper part of the arkose may show a
rude stratification and may grade upward into a well-stratified
deposit. The lower portion is massive and grades downward into
the granite, and may show the unaltered cores of bowlders of exfolia-
tion.
A good example of this type of arkose is to be found in the lower
arkose in the Silurian at Littleton, New Hampshire. Between the
Niagaran Limestone and the granite there is from two to eighty
feet of arkose which is coarse and granitic in appearance. The
quartz and feldspar are the same as those of the underlying granite
and are present in practically their original proportions. Thereis a
slight amount of a fine-grained dark matrix. In its upper portion,
the formation shows faint traces of stratification and in its lower
portion it grades into the underlying granite-gneiss. Locally the
original spheroidal weathering and the unaltered cores and shells
of concentric weathering are distinguishable.
To this type of deposit are to be referred:
The arkose (in part) of the Vermont formation (Cambrian), Massachusetts
and Vermont
The basal arkose (Silurian) at Littleton, New Hampshire
Pre-Cambrian arkose (in part) of the Cobalt District, Ontario
Basal arkose, Narragansett Basin, Massachusetts and Rhode Island
Nubian arkose, Aswan, Egypt
D. SUMMARY
The geological significance of arkose in brief, then, varies from
case to case and cannot be limited in the general statement to
significance of a special set of conditions. Each deposit is sig-
nificant of some special set of conditions and these in many cases
can be determined from the individual deposit or its associations.
In the preceding discussions an attempt has been made to show a
grouping of these in conformity with a genetic classification of
arkose, each type of which is significant of some special type of
CLASSIFICATION OF ARKOSE DEPOSITS 449
conditions. But even if the premises of this classification should
be seriously disputed, it still remains a fact that most formations
lying unconformably on a former granitic terrane have arkose at
or near the base, and there seems to be a more or less general rule
that, whenever a period of deposition is inaugurated over a granitic
terrane, arkose is the first or one of the first deposits to be laid down,
whatever the prevailing conditions. ‘This basal arkose commonly
shows but slight effects of wear and is apparently near the point
of origin of its constituent material. At higher horizons, there
often is yet other arkose, in most cases showing more signs of wear
and apparently having been transported for a greater distance;
and in still other cases, as has been noted, arkose composes the whole
of a formation, thousands of feet in thickness. The deposits are
of such differing types and have such different associations with
coal measures, with mud-cracked red beds, with beds containing
faceted pebbles, and with beds carrying marine fossils, that the old
conception of the limited significance of arkose is manifestly
incorrect, and arkose must be significant of several types of
conditions.
AN UNUSUAL FORM OF VOLCANIC EJECTA?
WALLACE E. PRATT
Chief Division of Mines, Bureau of Science, Manila, Philippine Islands
In the course of a study of the eruption of Taal Volcano, in
southwestern Luzon, Philippine Islands, during the month of
February, 1911, I noted the presence of small concretion-like
bodies in the finest-grained portion of the blanket of fragmental
ejecta which the eruption spread over the surrounding country.
It will be recalled that the eruption in question was characterized,
by the expulsion of great volumes of water-vapor, charged with
ash or sand, together with a small proportion of coarser fragmental
material. The eruption destroyed completely a dozen small
villages, with attendant damage to crops and live stock, and killed
1,335 people. A thin layer of mud and dust was spread over an
area of about 1,000 square kilometers, extending principally to the
north and west of the crater. I commented upon the presence of
the spherical bodies in the ash-fall at the time as follows:
An interesting feature of the fall of the ejecta is the formation of drops
or balls of mud. These were observed most abundantly on the island itseif,
but were seen at Talisay and Banadero also. They range in size from large
shot to hazelnuts, and when broken sometimes show concentric markings.
Apparently they fell late during the activity, being found just below the sur-
face of the deposit. These mud balls cannot be classed as lapilli in the strict
sense of that term, since they are built up, probably through the condensa-
tion of steam into drops of water. The accompanying vertical section of the
fall of mud or ash [text Fig. 2] was taken on the southwest slope of the volcano?
Text Fig. 2, referred to in the quotation, is reproduced here-
with as text Fig. 1.
Taal Volcano forms an island near the center of a lake from
15 to 20 kilometers in diameter. Thus the mud balls, which were
found both on the slopes of the volcano and at the villages of Talisay
« Published by permission of the Director, Bureau of Science, Manila, Philippine
Islands.
2 Wallace E..Pratt, Phil. Jour. Sci., Sec. A (t911), VI, 71.
450
AN UNUSUAL FORM OF VOLCANIC EJECTA 451
and Bafiadero on the margin of the lake, from 6 to 8 kilometers
distant from the crater, must have been widely distributed; never-
theless, at the time I was inclined to attribute their formation
to accidental, rather than to common, conditions of explosive
volcanism. The literature accessible to me revealed little evi-
dence that ejecta of this character had been observed generally,
although the following description by Edward Otis Hovey of
“drops of mud,’ which he encountered after the eruptions on
‘Martinique in 1902, shows that simi-
lar phenomena have been noted: Present Surface
ane Very fine ash
In addition to the showers of dry dust |
and ashes, there fell during the eruption
an immense amount of liquid mud which
had been formed within the eruption cloud
through the condensation of its moisture.
This mud formed a tenacious coating over
everything with which it came in contact.
That drops of mud, too, formed in the air
and fell as a feature of the eruption is
proved by the condition of the walls the of
houses in Precheur, on which I found flat-
tened spheroids of dried mud which could [/ermer Surface
have formed only in the manner indicated.
These flecks of mud were two, four, and Gill om ine soniimedion loss of
even six inches across, where two or more Jaaj Volcano in January, rgrr,
had coalesced. They occurred mostly on showing balls of dried mud near top
the northern and eastern walls of the of layer.
houses. The testimony of the people as
to the occurrence of rain during the great eruption is conflicting, but the evidence
of the coating and these drops of mud proves that much aerial condensation
of steam accompanied these outbursts.t
Mud balls (ash)
|
|
|
|
§
|
|
|
|
Fic. 1.—Section of ash which
More recently I have come upon evidence which leads me to the
belief that the formation of mud balls has been rather character-
istic of that type of volcanic activity which results in the explosive
eruption of great clouds of dust-laden steam, at least where atmos-
pheric conditions similar to those on the island of Luzon prevail.
In the examination of samples of strata pierced in drilling for artesian
water at the towns of Bauan and Taal, distant 25 and 15 kilo-
raeters, respectively, from the crater of Taal Volcano, abundant
1 Edward Otis Hovey, Am. Jour. Sci., XIV (1902), 343.
{
452 WALLACE E. PRATT
spheroidal and ellipsoidal inclusions were found which are indis-
tinguishable from the mud balls of the last eruption of Taal.
These ejecta may have come from Taal itself, or from some other
of the numerous small craters which are known to have existed
in southwestern Luzon formerly. The wells were drilled by the
Bureau of Public Works with standard drilling rigs, and the samples
Pe | |
=
Fic. 2.—Photograph of balls of dried mud which fell with the fine tuff portion
of the ejecta of Taal Volcano, in the eruption of rort.
studied were submitted by the drillers. The balls of dried mud
came from depths of from too to 150 meters in very loosely con-
solidated, silt-like volcanic tuff, fragments of which had evidently
caved into the well and had been brought to the surface by the
sand pump or bailer. Some of the balls were broken, but many
were intact in spite of the disintegrating effect which the rushing
action of the water into the bailer must have caused.
The size and appearance of the balls are well shown in the
accompanying photograph (Fig. 2). One specimen still imbedded
AN UNUSUAL FORM OF VOLCANIC EJECTA 453
in the tuff appears near the center of the photograph. The broken
surfaces display clearly the concentric structure which is charac-
teristic of these bodies. The balls can be disintegrated between
the fingers when wetted, and the individual particles prove to be
like dust in size. That these aggregates have not resulted from
solution processes nor from dynamism is evidenced by the facts
that they do not contain calcium carbonate nor any other extra-
neous cementing agent, and that the beds in which they occur have
certainly not experienced metamorphism. The theory which
Dr. Hovey advanced to explain the presence of ‘‘drops of mud”’
in the ejecta from Mont Pelée accounts satisfactorily for the
similar, although apparently smaller, balls of dried mud in the
loose tuffs of southwestern Luzon.
W. H. Brown, botanist, Bureau of Science, has submitted to me
several hundred balls of dried mud which he found included “in
the upper part of a thick bed of volcanic tuff”? on the slopes of
Mount Maquiling, an extinct volcano about 20 kilometers north-
west of Taal. He had been engaged in a study of the flora of
Mount Maquiling and had encountered these balls in the course
of a soil survey. They are precisely like those already described
in shape and structure, but many of them are larger and they
have a brownish-yellow color, whereas the Taal products are light
gray in color. They consist of the same material as the inclosing
bed—clayey, fine-grained tuff. The balls from Maquiling attain
a diameter in rare specimens of as much as 4 centimeters, thus
being comparable in size with the drops of mud observed by
Dr. Hovey, and are so hard that they can be broken only with diffi-
culty between the fingers. The appearance of a face in the tuff bed
containing these balls is shown in Fig. 3. The concentric structure
of the balls is again revealed in this photograph.
Recently, also, I have encountered well-preserved balls inclosed
in clayey tuff on Bondoc Peninsula, Tayabas Province, and near
the Santa Lutgarda iron mine at Angat, Bulacan Province, widely
separated parts of Luzon. The tuff beds in these localities are of
greater age than the recent tuffs in the Taal volcanic region,
dating back, probably, to the late Miocene. The tuff is slightly
indurated, but the balls have retained their form and display
454 WALLACE E. PRATT
clearly the characteristics already recorded in describing the ejecta
from Taal. Iam confident that they originated in the same manner
in each case.
The suggestion arises, in view of the foregoing observations,
that the condensation of mud into drops or balls must be a rather
common feature of volcanic eruptions which throw out great clouds
of water-vapor and fine sand or dust. The product may be
Fic. 3.—Photograph showing close view of a face in a bed of clayey tuff con-
taining “‘mud balls’’; slopes of Mount Maquiling, southwestern Luzon. About one-
third natural size.
described, perhaps, as a volcanic hailstone. Undoubtedly, the
contour of such bodies is often destroyed by the impact of the fall
to the ground surface. Probably only where the drops have had
opportunity to dry out somewhat before reaching the earth and
where they strike in soft, unconsolidated beds of recently fallen
tuff, is their form preserved under subaerial conditions. It would
appear to be equally remarkable that they should retain their form
upon falling into water. Yet it is beyond question that the tuff
series into which the wells at Bauan and Taal penetrated is in
great part water-laid, and it is to be presumed that the mud
AN UNUSUAL FORM OF VOLCANIC EJECTA 455
balls encountered in the wells at these towns fell into the sea
originally.
Unless conditions peculiar to the tropics, such as high temper-
ature and, perhaps, excessive humidity, are essential factors in the
phenomena which have been described, it would appear that mud
balls should have been formed in the eruption cloud from Katmai
Volcano in Alaska and in the recent eruptions of Mount Lassen
in California. So far as I have observed, none of the published
accounts of the eruptions of these volcanoes have mentioned ejecta
of this character.
RIPPLE-MARKS IN OHIO LIMESTONES*
CHARLES S. PROSSER
Ohio State University
INTRODUCTION
ORDOVICIAN RIPPLE-MARKS
Elk Run
Cherry Fork
Trebers Run
Review of Previous Work
SILURIAN RIppLE-MARKS
Beasleys Fork
Lick Fork
Sproull Glen
Lawshe Quarry
Elk Run
Sharpsville
Near Peebles
Near Locust Grove
Leesburg
Monroe Formation
DEVONIAN RIPPLE-MARKS
Sandusky
INTRODUCTION
Dr. Edward M. Kindle, in a “Note on a Ripple-Marked
Limestone” in the Devonian of northern Manitoba, published in
1912, stated that: ‘‘the occurrence of ripple-marks on sandstone is a
common phenomenon to every geologist... . . The literature
on ripple-marks relates almost entirely to these familiar sand or
sandstone ripples. The occurrence of ripple-marks on limestone
seems to be a phenomenon of such relative infrequency that it
appears desirable to record an example which has come under the
writer’s notice.” In a later paper Dr. Kindle has described ripple-
t Published by permission of the State Geologist of Ohio.
2 Ottawa Naturalist, XX VI (December, 1912), 1 (reprint).
450
RIPPLE-MARKS IN OHIO LIMESTONES 457
marks in the Trenton limestone near Hull, Quebec,’ and given a
summary of previously described ripple-marks in American lime-
stones.? At an earlier date Dr. August Foerste had noted the
occurrence of wave-marks (ripple-marks) in the Ordovician and
Silurian limestones at a number of localities in Kentucky, Ohio,
and Indiana. Recently Professor J. A. Udden has described
ripple-marks in the Burlington limestone of Iowa and in limestones
of Comanchean age in Texas.4
On account of the comparative infrequency of described observa-
tions of ripple-marks in limestone the writer has concluded to record
the most conspicuous of those which he has seen while engaged
in field work in Ohio. These will be grouped in the several geologic
systems in which they were observed, arranged in ascending order.
ORDOVICIAN RIPPLE-MARKS
Elk Run.—The best ripple-marks seen in the Ordovician are in
the upper part of the Richmond formation on Elk Run in the
northwestern part of Adams County. This locality is on the
Marion Dunlap farm, about 14 miles east of Winchester and 3 miles
west of Seaman, where the ripple-marked layer of limestone forms
the floor of the run for a considerable part of the distance between
the Norfolk & Western Railway trestle and the highway bridge.
An excellent view of these ripple-marks may be had from the
Norfolk & Western passenger trains while crossing the trestle
if one looks downstream to the north.
The first series of ripple-marks is on a layer forming the bed of
the run a short distance below the trestle and continuing up a
branch from the west for about two rods. The direction of the
ripple-marks is about due north and south. The more gradual
slope (stoss) is to the east, and the steeper (lee) to the west. The
distance apart (amplitude) of the crests varies from 28 to 32 inches
t Jour. Geol., XXII (1914), 707-0.
2 [bid., pp. 709-11.
3 Jour. Geol., III (1895), 50-60 and 169-97; 1-40 (reprint); Jour. Cincinnati Soc.
Nat. Hist., XVIII (1896), 167; Am. Geologist, XX XI (1903), 333-61.
4 Jour. Geol., XXIV (March, 1916), 125, 126; illustrated by Fig. 3, p, 126, Fig.
4, Pp. 127, and Fig. 5, p. 128.
458 CHARLES S. PROSSER
in the more normal ones, with, in some instances, shorter and more
irregular ones between these crests. The depth of the troughs,
from the crest to the bottom, varies from 2 to 3 inches. The
crests undulate or curve slightly in crossing the surface of the lime-
stone, and this undulation is conspicuous in the bed of Elk Run
a little below the branch. Fig. 1 shows the ripple-marks in the
Fic. 1.—View of ripple-marks in bed of Elk Run, just below the Norfolk &
Western Railway trestle, 1} miles east of Winchester, Ohio. Photograph by C. S.
Prosser.
bed of Elk Run, just below the railway trestle, and also on the
same layer of limestone in the bed of the small western branch.
There is a dip of at least 1° to the east as measured on the
crests of the npple-marks in the lower part of the branch, and
farther up this stream it increases to 2°. The layer of limestone
contains large numbers of shells which Dr. Foerste states are
covered by sand.t It is rather difficult to make out the sand,
although there is granular material to some extent. This horizon
t Jour. Geol., III (1895), 50.
RIPPLE-MARKS IN OHIO LIMESTONES 459
is given by Dr. Foerste as 60 feet below the top of the Richmond
formation.*
The dip downstream carries this ripple-marked layer down Elk
Run to where it covers the entire bed of the stream for some dis-
tance above the highway bridge. At this locality the bed of the
stream which is covered by the ripple-marked layer is some 60 feet
wide and extends 156 feet along the bed of the stream. This is a
beautiful example on a large scale of a ripple-marked limestone.
The trend of the crests of some of these ripple-marks is N. 3° W.,
and they undulate to a considerable extent in crossing the stream.
The crests of the normal ripple-marks are from 27 to 32 inches
apart. The crests of about three out of five are 29 inches apart, and
the average over different parts of the surface of this layer is 29,
30, and 31, inches apart. The more gradual and longer slope
(stoss) is to the east, the steeper and shorter slope to the west, and
the ripple-marks are clearly asymmetrical. A view of the ripple-
marked bed of Elk Run at this locality, looking downstream
toward the highway bridge, is shown in Fig. 2. A view of the bed
of Elk Run from the highway bridge looking upstream, with the
railway trestle in the distance, is shown in Fig. 3.
The layers on the western side of Elk Run below the highway
bridge are dipping from 3° to 425 N. 10 E. The majority of
readings on the different layers, however, gave 3° for the amount of
dip. The barometer gave a dip of 5 feet to the east for the surface
of the ripple-marked layer from the branch to the bed of Elk Run
under the highway bridge, a horizontal distance of 500 feet.
Just below the highway bridge on the western bank is a ripple-
marked layer, between 2 and 3 feet higher than the fine one in the
bed of Elk Run which has just been described. The ripple-marks
of this higher layer run N. 30° W., are not so conspicuous as in
the lower layer, and do not show much difference in the slope of
the two sides. On the western side of Elk Run, not far below the
highway bridge, is the house of Mr. Charles L. Bailey, and near
water-level above the house is a set that runs about northwest
and southeast. The eastern slope of these ripple-marks is more
gradual than the western slope. Just below the Bailey house a
Ibid., p: 58.
460 CHARLES S. PROSSER
fall is formed by a ripple-marked layer in which the ripples run
N. 3-5° W., and the steeper slope is to the west. The crests are
from 27 to 28 inches apart, and the ripples are more irregular than
those in the bed of Elk Run above the highway bridge. It is not
certain that this is the same layer as the one above the highway
bridge, and Mr. Bailey, who is interested in geology, states that
~
‘5
~w
Fic. 2.—View of ripple-marked bed of Elk Run, looking downstream toward
the highway bridge. Photograph by C. S. Prosser.
it is lower. Below the ripple-marked layer in the fall is another
one with the ripples running N. 10° W., and the steeper slope
to the east, with a more gradual one to the west.
Farther down Elk Run, shown for some rods in the bed of the
stream and making a lower fall, is a conspicuous ripple-marked
layer, which is 5+ feet below the one forming the Bailey fall.
These ripple-marks run N. 1o-16° W., the crests are undulating, the
slopes steeper to the west than to the east, and the crests from 21,
26, to 27 inches apart. Farther down the run on the eastern side,
opposite the E. E. Jamison house, where the pike comes down into
RIPPLE-MARKS IN OHIO LIMESTONES 461
the valley of the stream, is a ripple-marked layer. The ripple-
marks are not so clearly defined as in the layers farther up the
stream; but they apparently run about north and south. Loose
blocks of limestone containing pebbles were noted at this locality;
but the layer was not located in place. Probably this is the
locality described by Dr. Foerste when he says, “Within half a
Fic. 3.—View of ripple-marked bed of Elk Run from the highway bridge looking
upstream, with the railway trestle in the distance. Photograph by C. S. Prosser.
mile of the bridge, farther down, opposite a house on the east bank,
plenty of pebbles occur in the rock.”* Farther down the stream,
below the next house on its western side and a ford, is a still lower
layer, with not very clear ripple-marks.
As noted above, the ripple-marks in the limestones along this
stream were first described by Dr. Foerste as wave-marks on
Elk Horn Creek.?
Cherry Fork.—Ripple-marks in the Upper Richmond were
also seen in the bed of Cherry Fork, below the highway bridge at
1 Op. cit., Pp. 59. 2 Ibid., pp. 58-60.
462 CHARLES S. PROSSER
Harshaville, 4 miles southeast of Seaman, Adams County. The
ripple-marks in the highest limestone layer below the bridge run
about N. 60° W. and have the more gradual slope ‘to the east of
south, and the more abrupt to the west of north. ‘The crests vary
from 20 to 28 inches apart. In another limestone layer about 6
inches lower than the first one the ripple-marks run north and
south, with the steeper slope to the west and the more gradual one
to the east. The crests are from 20 to 30 inches apart. Over part
of the floor of the creek below the bridge is a less distinctly ripple-
marked layer between the two which have just been described.
These run almost directly northwest and southeast, the crests are
from 22 to 28 inches apart and are rather flat, and the slope is
about the same on each side, making them nearly symmetrical.
The northeast slope on a few of them is a little steeper and these
do not have such flat crests. Perhaps the tops of the crests of the
others have been worn away, which gives them the present some-
what flattened form,
Trebers Run.—This stream is a western tributary of Lick Fork
(called Lick Creek on the Highway Map of Adams County), about
5 miles northeast of West Union, 2} miles below Young’s Chapel,
about a mile above Dunkinville, and 9 miles southwest of Peebles.
On the southern bank of Trebers Run, about 150 yards above the
covered bridge on the West Union and Jacksonville Pike, is a
ripple-marked limestone layer exposed for 90 feet or more along the
bank. This limestone layer is in the upper part of the Richmond
formation. At the time this locality was visited the streams were
high and the layer was partly covered by water, so that the con-
ditions were not especially favorable for study. Three adjacent
ripple-marks run as follows: N. 12° E., N. about 12° E., and the
third one about N. and S. The distance between the crests varies
from 2 feet 2 inches to 2 feet 7 inches, while the depths of the
furrows (troughs) is from 23 to 3 inches. The eastern slope of the
ripple-marks is perhaps a little steeper; but there is comparatively
little difference in the slope of the two sides. There is a heavy
dip for this region downstream to the east, and certain layers on the
northern bank some rods farther up the run dip from 4°5 to 5° N.
100 E.
RIPPLE-MARKS IN OHIO LIMESTONES 463
This stratum is known locally as the ‘‘washboard” layer, and
it is apparently the one described by Dr. Locke in 1838. He stated
that ‘‘the waved stratum at Treber’s is exposed in the bed of the
fork, about 400 feet in length, and 50 feet in width.”* Mr. William
Treber, now eighty-nine years old (July, 1915), who lives on the
Treber farm just south of the run, remembers when Dr. Locke
studied this locality, and his daughter, Lizzie Treber, stated that
the layer described by Locke is believed to have been exposed in
the field a few rods northeast of the lower part of Trebers Run, on
the eastern side of the Pike. Lick Fork has shifted its bed some-
what to the east and the locality is now covered by soil. The
strong easterly dip would probably carry the layer now exposed on
Trebers Run down to the locality where it is stated that the ripple-
marks described by Dr. Locke were exposed. The barometer gave a
difference in altitude of 110 feet from Lick Fork at Trebers to the
top of the Richmond formation on Lick Fork above Young’s
Chapel, 25 miles above Trebers. Miss Treber also stated that
formerly the ripple-marked layer was exposed in Lick Fork, about
opposite their house, as well as above it; but the high water at
the time this locality was studied prevented determining whether
any of the layer is now shown when the water in the stream Is at its
normal height.
Review of previous work.—Ripple-marks in the Upper Richmond
in Ohio, so far as known to the writer, were first described by
Professor John Locke from outcrops on Lick Fork,? about 5 miles
northeast of West Union, Adams County. Locke called it the
““waved stratum”’ and located its horizon as 55 feet below the top
of the blue limestone, No. V of his section, and he stated that
near a house known as Trebers it was exposed ‘“‘in the bed of the
fork, about 400 feet in length, and 50 feet in width.’ Professor
Locke, however, stated that ‘‘these waves are not local, but may
be traced in the same stratum over tracts of many miles. They
have been called ‘ripple marks’; but all geologists will agree that
the blue limestone has been formed far below the reach of ‘ripples.’’”4
* Second Ann. Rept. Geol. Survey Ohio, 1838, p. 247 and bottom of Pl. 6, opposite
Pp. 242.
2 Second Ann. Rept. Geol. Survey Ohio, 1838, pp. 246, 247, and Pl. 6, opposite p. 242.
3 [bid., p. 247. 4 [bid., p. 246.
464 CHARLES S. PROSSER
Messrs. Joseph Moore and Allen D. Hole have described
“ripple-marks in Hudson River limestone, in Wayne County,
Indiana, 5 miles southwest of Richmond,” which are illustrated
by 3 plates... These are probably in the Richmond formation and
it is stated that ‘‘the mean distance from crest to crest is approxi-
mately uniform for the series, and the average for twenty such
distances is found to be 2.63 feet. The average depth of lowest
part of troughs below crests is 14 to 1;%y inches.’ At an earlier
date W. P. Shannon had described ‘“‘wave-marks on Cincinnati
limestone”’ in the bed of Salt Creek, 3 miles west of Oldenburg,
in the southwestern part of Franklin County, Indiana.
Dr. Orton called attention to the observations of Professor
Locke and stated that ‘it is an even more striking characteristic of
the rock in its lower beds [Cincinnati group], as shown in the river
quarries of Cincinnati, or in the lowermost too feet that are there
exposed. . . . . The interval between the ridges varies, but in
many instances it is about 4 feet. The greatest thickness of the
ridge is 6 or 7 inches, while the stone is reduced to 1 or 2 inches at
the bottom of the furrow, and sometimes it entirely disappears.’
Dr. Foerste also noted wave-marks and ripple-marks in the “ Lower
Hudson, or Utica’ opposite Cincinnati, at West Covington,
Kentucky,’ which in general “run slightly east of north.’
Recently Dr. Kindle has reported Dr. Foerste as stating that
“wave-marks (ripple-marks) occur in Ohio, Indiana, and Kentucky,
in abundance in the Lower Eden, Upper Richmond, and Upper
Brasstield limestones. They occur in great numbers, but not so
abundant, also in the Middle Eden. In Kentucky they are
common also locally in the Mount Hope bed, at the base of the
Maysville. They occur often near the middle of the Arnheim and
at various intervals in the Lower and Middle Richmond in the
three states mentioned.’”
* Proc. Indiana Acad. Sci., t901 (1902), pp. 216-20.
2 Tbid., p..217.
3 Ibid., 1894 (1895), pp. 53, 54.
4 Rept. Geol. Survey Ohio, I (1873), 377-
5 Jour. Geol., III (1895), 56-58.
® Tbid., p. 58. ? Ibid., XXII (1914), 709, 710.
RIPPLE-MARKS IN OHIO LIMESTONES 465
SILURIAN RIPPLE-MARKS
Beasleys Fork.—Ripple-marks in the upper part of the Brass-
field limestone (formerly called Clinton) were noted at several
localities in Adams County. One of these localities is in the bed
of the upper part of Beasleys Fork, some distance above the house
of Walter D. Grooms, which is about 1} miles south of West Union
on the Wrightsville Pike. This stream is crossed by three layers
of limestone in which ripple-marks are conspicuously shown.
The lowest layer is a very crinoidal limestone, from 3 to 10
inches thick, which forms a small fall, and its top is about 8 feet
3 inches below the top of the Brassfield limestone. The ripple-
marks run about east and west, with the more gradual slope to the
north and the steeper toward the south. ‘The top of the second or
middle ripple-marked layer is 4 feet 11 inches below the top of the
Brassfield formation, and the layer itself is 5+ inches thick, but,
the ripple-marks are not so conspicuous as in the layer below and the
one above. These ripple-marks run north and south with the
steeper slope on the east side and the more gentle slope on the
west. Finally, there is the third or highest ripple-marked layer,
the top of which is 4 feet 5 inches below the top of the Brassfield,
and opposite the small house on the bank of the creek on the Joe
Morrison farm. The layer is a grayish, somewhat greenish-
spotted, crystalline limestone, 8+ inches thick. The ripple-
marks run about north and south, with the steeper slope to the
east and the more gradual to the west. ‘These ripple-marks are
heavy and the crests are 26, 31, 34, 35, and 38 inches apart. The
distance from the bottom of the trough to the top of the ridge
varies from 3 to 9 inches.
These ripple-marks were noted by Dr. Foerste in his description
of the section ‘‘along the road to Beasley Fork.” The following
is that part of this section in which the ripple-marks occur, as
described by Dr. Foerste:*
Ft. In
WESTON eC BWAVC-INAE KEG Meme ce til heres cece aie gies ¢ aedldie ni coetargiehens mie eters a
CERT dio ao MRIS Oop CHAE aE ol errene cathe INIA” Searls IMR ERR Bein ESTE eRe ANre vere SLA 8
TGA ESEOMLC MN ONT soe ret eric AS cavalrou vlc Ye drs carats By a areal ceapha see 3
CEST @ Bach aight PMN SINS 0) 2 Dad a a a anaes ee airs Mad Sa 3
t Kentucky Geol. Survey, Bull. No. 7, 1907, Pp. 42.
466 CHARLES S. PROSSER
Ft. In
Limestone, with large waveamarksys a. 2.0). ss. 0.5245 aes ee ate 6
LAMIESCONENS gi) ice As jae Fekete Mem RS ETA aS ed sesisLxeh es ocek gtd eke oy 6
Clay, witha little thimilitnest@ner cack. s cits ds. oe cs aie ee ee Ee O
Limestone with large wave-marks and containing large crinoid beads. . 6
Lick Fork.—At least two ripple-marked layers in the upper
part of the Brassfield limestone occur on Lick Fork (called Lick
Creek on the Highway Map of Adams County) above and below
the highway bridge on the West Union and Jacksonville Pike,
about 2} miles northeast of West Union and about opposite the
house of J. Frank Young. Stratigraphically, what is apparently
the lowest ripple-marked layer outcrops a few rods above the
bridge, where there is a strong dip downstream. ‘The rock of this
layer is a very crystalline and crinoidal limestone containing large
cup corals and numerous fragments of other fossils in its upper
surface. The ripple-marks are large and one of them runs N. 70°
E., although some of them run perhaps more nearly east and west.
The crests of two of them are 30 inches apart, and of another set
31 inches apart. The trough is 33 inches deep and the slope
much steeper on the southern than on the northern side. A few
rods below the bridge is a layer with ripple-marks which run N. 20°
W. and S. 20° E. The crests of these ripple-marks are about 31
inches apart and the western slope is steeper than the eastern one.
This ripple-marked layer is about 19} feet higher than the base
of the Brassfield limestone. Not far above the highway bridge
are ripple-marks running N. 18° W. and S. 18° E., which apparently
occur in the same layer as those below the bridge, which ‘have
just been described. Farther upstream the direction of the ripple-
marks, apparently on this same layer, has changed to N. 74° W.
Not much farther upstream than the ripple-marked layer first
described one is shown in the bed of the stream, which may be
higher than the others; but its stratigraphic position was not
certainly determined. The ripple-marks of this layer run north
and south, the crests are 30-35 inches apart, and there does not
appear to be a marked difference in the angles of the slopes.
This is probably the locality where Professor John Locke noted
two waved layers in the Flinty limestone (Brassfield), No. III of his
RIPPLE-MARKS IN OHIO LIMESTONES 467
section, on Lick Fork.t He gave the top of the upper one (No. 13)
as 4 feet 93 inches below the top of a flinty layer (No. 1) (appar-
ently one of the layers of the Dayton limestone), which he seemed
to consider the top of the flinty limestone. This upper “waved
stratum” is given as 3 inches thick, with 20 inches mostly of marl
between it and the lower “‘ waved layer” (No. 17) which is reported
as 7 inches thick.
Sproull Glen.—This glen is on the R. C. Sproull farm, now owned
by Mrs. Jennie Black and Dr. O. T. Sproull, not far from Sproull
Bridge over Ohio Brush Creek, 6 miles southwest of Peebles. The
heavy rains of July, 1915, had deepened and cleared out the bed of
this stream to such an extent that three layers of ripple-marked
limestone were exposed which on a visit to the same glen in Sep-
tember, 1914, were not seen.
The lowest ripple-marked layer was shown on the northern side
of the stream with ripple-marks running N. 10° W. to N. 30° W.
One foot 5 inches higher is another limestone layer 7 inches thick
with ripple-marks imperfectly shown on its upper surface. Also
3 feet higher ripple-marks occur on thin layered limestones; but
the last two layers were so poorly shown that not many data could
be obtained concerning the ripple-marks. The top of the third or
highest ripple-marked layer is 9 feet 9 inches below the base of the
to-inch zone of Whitfieldella quadrangularis Foerste} in the Brass-
field limestone, and 9g feet 3 inches below the top of this formation
as exposed in the third fall, or 13 feet 6 inches below the top of the
very hard Dayton limestone as exposed in the stream above this fall.
Lawshe quarry.—This old quarry is located on the Vincent
Robbins farm, north of Lawshe, Adams County, on the Cincinnati
Division of the Norfolk & Western Railway. Ripple-marks were
noted near the western end of the quarry, which are not well exposed
but run N. 16° E. The ripple-marked layer occurs from 1 foot
4 inches to 2 feet below the base of a rather conspicuous 2 foot 2 inch
Second Ann. Rept. Geol. Survey Ohio, 1838, pp. 244, 246, and Pl. 6, opposite p. 242,
on which only one waved layer is indicated in the flinty limestone.
2 [bid., p. 244, where he states that ‘‘the upper layer of the flinty stratum is
peculiarly marked. It is about one foot thick, and contains so much silex that it has
the sharp conchoidal or flinty fracture, and gives fire with steel.”
3 Kentucky Geol. Survey, Bull. No. 7, 1906, p. 41.
468 CHARLES S. PROSSER
layer, which is 12 feet 10 inches above the top of the ‘‘chert zone”’
in the basal part of the Brassfield limestone and 16 feet 10 inches
higher than the lowest outcrop in this quarry. The 2 foot 2 inch
layer is variously colored crystalline limestone, which on the
weathered faces is apparently cross-bedded and contains a good
many pebbles, more or less flat, and some of them of considerable
size. The top of the massive layer just described is about 22 feet
below the top of the Brassfield limestone and nearly 243 feet below
the top of the hard Dayton limestone.
Elk Run.—On Elk Run (called Elm Run on the Highway
Map of Highland County), 2} miles northeast of Belfast, High-
land County, are ripple-marked layers in the Brassfield limestone,
which are well shown in the stream a few rods below the iron high-
way bridge on the upper road from Belfast to Elmville. This layer
is a crystalline limestone, from } to 3 inches thick, which contains
fossils and some pebbles. The ripple-marks run N. 80° E., the
steeper slope is to the north and the more gradual one to the
south. The crests range from 26 to 36 inches apart, 32 inches being
the most frequent distance. The deepest trough noted is about
2} inches lower than the crest. A ferruginous limestone 1 foot
4 inches thick occurs just above the crystalline, ripple-marked
layer, and another 4-inch ferruginous limestone layer just above
this, the upper surface of which is apparently ripple-marked.
Below the ripple-marked, crystalline limestone is a layer 1 foot thick
containing fossils and numerous pebbles of Brassfield limestone.
The majority of the pebbles are rather flat and fairly well rounded
on the margins. The size of some of the larger pebbles is indicated
by the following figures: one 8} inches long, and three rectangular
ones respectively 9X6, 9X8, and 9X83 inches. The pebbles asia
rule lie flat (horizontal) or at least nearly so in the rock; but there
are some that are imbedded at more or less of an angle.
Attention was first called to this locality by Dr. Foerste, who
has written as follows concerning it:
By far the most interesting feature of the locality, however, was the
presence of great wave-marks, wonderfully distinct and well exposed for a
distance of a hundred feet down the creek. The line of strike of these wave-
marks was magnetically about north 65° east. The crests of the wave-marks
RIPPLE-MARKS IN OHIO LIMESTONES 469
were about two inches above their greatest depressions, and the distance
from one crest to the next was on the average about 28 inches. They sloped
northwards a little more steeply than southwards. This wave-marked layer
is only from one to two inches in thickness; and immediately overlies a
great mass of pebbles, imbedded in the Clinton just beneath. These pebbles
sometimes project strongly into the sandy layer above, which shows the
wave-marks. The pebbles are on the average larger than at any place where
pebbles have so far been seen in the Clinton. Plenty of them are 12 inches in
Fic. 4.—View of ripple-marks as formerly shown in the old Schoepfle quarry,
Sandusky, looking southeast. Photograph by C. W. Platt.
diameter, and many of them range between four and eight inches. As usual,
the pebbles are only an inch to an inch and a half in thickness. Lithologically
they are similar to the sandy stratified layers of the Clinton limestone, found
characteristically in the lower half of the Clinton in this part of the state, and
occurring also at higher levels. If there had been any doubt hitherto about
the Clinton age of these pebbles, it was dispelled by the fossils found in some
of the pebbles at this locality.t
Shar psville-—On Turtle Creek, above Sharpsville, in the western
part of Highland County, ripple-marks were noted in the Brass-
field limestone; but there was not an opportunity to measure
t Jour. Geol. III (1895), 184.
470 CHARLES S. PROSSER
them. Opposite Sharpsville and farther down Turtle Creek than
the place above mentioned Dr. Foerste reported “‘a thin, sandy
layer, very undulated, like ripple-marks where waves have crossed
from various directions. Their importance was not appreciated,
when observed, and their direction was not carefully noted.
Judging from the memory alone the larger ripples had a general
northeast course and indicated currents transverse to this direc-
tion.””?
Near Peebles ——In the Peebles Stone Company quarry, on the
northern side of the Norfolk & Western Railway, one-half mile
west of Peebles, is a layer 7 feet 10 inches above the base of the
West Union limestone, the surface of which is conspicuously ripple-
marked. The rock is bluish gray in color, massive, contains
Brachiopods, and the upper surface is very crinoidal. On the
crests of the ripple-marks are furrows which are apparently trails,
The majority of the ripple-marks run in a regular direction, which
is N. 6° W.; but an occasional one runs in an irregular direction.
The distance between two parallel crests is 27 inches and the trough
is 17 inches deep. The distance between two other conspicuous
crests is 3 feet ro inches, with a much smaller ripple-mark about
half-way between them. In general the eastern slopes appear
to be the steeper, although part of them do not show any particular
difference, and one is apparently steeper on the western side.
About one-fourth mile west of Peebles in the bank of a small
stream on the northern side of the Norfolk & Western Railway
ripple-marks occur in Niagaran limestone. Ripple-marks are
clearly shown in two layers of crinoidal limestone at this locality.
In the lower layer one of the ripple-marks runs N. 6° W., and another
one, N. 2? W. The crests are 22-23 inches apart and one trough
is 4 inches deep. In general the more gradual slope is to the east
and the steeper to the west, although in one of them the eastern
slope appeared to be the steeper. In the upper layer the ripple-
marks run N. 5° E., the crests are 44-45 inches apart, a trough
is 43 inches deep, and the steeper slope is to the east.
This locality was described as follows by Dr. Foerste:
Along the railroad about a quarter of a mile west of Peebles, where the
railroad crosses a creek, there are very good wave-marks in the rock on the
t Jour. Geol., III (1895), 178. ,
RIPPLE-MARKS IN OHIO LIMESTONES A471
north side of the railroad, in a sort of quarry. The rock is of a bluish tint,
and is some distance above the Niagara shales. It is presumably of the
Springfield horizon. The crests of the waves run here north 3° east; they are
about 3% inches above the troughs of the waves, and are about 42 inches apart,
showing therefore approximately the same characteristics as the waves of
Clinton age in Elk Run. They descend more rapidly eastward than westward.
The wave-marks are seen at several levels through a thickness of 23 feet
oe
Fic. 5.—Nearer view of part of layer shown in Fig. 4. Photograph by C. W.
Platt. s ;
Ole LOCK oc a. Where the railroad crosses the creek, 50 feet towards the
southeast, the wave-marks are shown over a larger area. ‘The crests here run
north 5° west.t
s
Dr. Kindle has also made reference to this locality.
Another locality of Niagaran ripple-marks is southwest of
Peebles on the dirt road for Lawshe, about one-fourth mile west
of the West Union and Locust Grove Pike. The ripple-marks
are shown in the highway to the west of a run, and the first house
to the west is that on the farm of James Graham. The ripple-
marks run north and south, the crests are 20, 21, and three of them
24 inches apart. The more gentle slope appears to be to the west
t Jour. Geol., III (1895), 190. 2 [bid., XXII (1914), 711.
472 CHARLES S. PROSSER ;
and the steeper to the east. These ripple-marks occur in somewhat
thin-bedded dolomites, like those to the west of Peebles, called
Springfield by Dr. Foerste, and apparently are in the southern
continuation of those beds.
Near Locust Grove.—On the western side of Locust Grove branch
of Crooked Creek, 1 mile west of Locust Grove and nearly opposite
the house of James Ogden, in the West Union limestone are ripple-
marks running N. 12° W. and S. 12° E. Some rods farther down-
stream and 30 feet higher on the bank in the West Union limestone
are rather large ripple-marks running N. 10° W. and S. 10° E.
Leesburg.—Ripple-marks occur in Lee’s Creek in the gorge
below the Davis Mill and north of Leesburg in the northern part
of Highland County. The ripple-marks occur in the Blue Cliff
dolomite, which Dr. Orton correlated with the Springfield dolomite,
and just below a massive layer 7} feet thick, which is well shown
on the eastern side of the creek where the rock has been quarried
to a small extent. The ripple-marks are rather irregular; but
one runs N. 30° E. and they appear to be steeper on the western
slope than the eastern.
Monroe formation.—Ripple-marks were noted at three horizons
in the Monroe formation, 23 miles east of Peebles; but the area
exposed in each case was too small and the ripple-marks too imper-
fect to make any definite measurements. The lowest layer is
exposed in the bed of Morrison Run some distance below the spring |
and house of John K. Morrison, on the road to Bacon Flat school-
house, and it is about 15 feet higher than the base of the formation.
The highest one is shown in the highway leading up the hill to the
west of the John K. Morrison house, and is stratigraphically some
86 feet higher than the base of the Monroe. The direction of ‘these
ripple-marks is somewhat irregular; but they run about east and
west. The third and intermediate horizon is on a layer in the
Virginia Product quarry, just south of the Norfolk & Western
Railway, about 25 miles east of Peebles, and it is more than 25 feet
above the base of the Monroe dolomite.
DEVONIAN RIPPLE-MARKS
Sandusky.—The best example of ripple-marks in the Devonian
limestone that the writer has seen is in Plant No. 2 of the Wagner
RIPPLE-MARKS IN OHIO LIMESTONES 473
Stone Company (formerly known as the Schoepfle quarry), on
Hancock Street in the southern part of Sandusky. Formerly there
was a considerable area of the floor of this quarry on which ripple-
marks were beautifully shown, the three views of which repro-
duced in this article were furnished by Mr. DeLos C. Ransom, of
Fic. 6.—View of ripple-marks as formerly ‘shown in the old Schoepfle quarry,
Sandusky, looking northeast and at right angles to Fig. 4. Photograph by C. W. Platt.
Sandusky, Ohio, who first called the writer’s attention to them in
January, 1902. Most of this area, however, has been destroyed
by the work of the Wagner Stone Company, and when studied on
September 19, 1914, only a small portion of it remained, which was
located about east of the crusher and on both the east and west
sides of the quarry track running from the crusher around to the
new part of the quarry to the northwest. This ripple-marked
474 CHARLES S, PROSSER
layer is in the upper part of the Columbus limestone, the western
continuation of the Onondaga limestone of New York.
In general, the crests of the ripple-marks which remained in
September, 1914, run N. about 20° W., but those farthest to the
west run N. about 25° W. Occasionally~two will run together
and, in one case at least, then diverge again. The crests of those
studied vary from 22, 24, 25 to 26 inches apart, the greater number
of them being about 2 feet apart. Mr. Ransom reported those
shown in the half-tones as ‘‘being 3 to 4 feet from crest to crest.’
In the somewhat worn surface of the layer it is dificult to distin-
guish any particular difference in the angle of slope of the two sides;
although, perhaps, some of the ripple-marks west of the quarry
track are a little steeper on the southwest side, with a little longer
slope on the northeast side. The troughs of these ripple-marks are
rather shallow, although the exact depth was not determined.
Figs. 4, 5, and 6 are from photographs, furnished by Mr. DeLos C.
Ransom, of the floor of the old (Schoepfle) quarry, showing the
tipple-marks as they formerly appeared before this layer was
mostly destroyed by the extensive work of the Wagner Stone
Company. Mr. Ransom has stated that in Figs. 4 and 5 the
camera was pointed toward the southeast and parallel to the direc-
tion of the ripple-marks. In Fig. 6 the direction across the ripple-
marks is toward the northeast, at right angles to Fig. 4, and the
crests are three or four feet apart.2 Mr. Ransom has written
several times concerning these: ripple-marks, and the following
quotation is from one of his letters:
Now such ripple-marks 3 or 4 feet wide as are in limestone must have
been constructed in water 50 to roo feet deep and waves of immense size in
the ancient comparatively shallow and wide sea when our limestones were
laid down. “Ripple-marks” hardly expresses or describes these large parallel
stone waves. They are perpendicular to the direction of the wind, hence aeons
ago winds were as now largely S.W. and N.E. and hence the poles of the earth
have not changed since.
t Letters of January 25, 1902, and October 28, 1903.
? Letter of September 25, rors.
3 Letter of October 28, 1903.
RIPPLE-MARKS IN OHIO LIMESTONES 475
On September 19, 1914, a considerable area in the new (north-
west) part of the quarry had been stripped of soil and this upper
surface of the limestone was beautifully glaciated. It was all worn
smooth and marked with striae of various degrees of strength;
but part of them are rather strong. ‘The direction of the striae
was determined at different places on this surface and in all cases
they ran N. 100° W. (W. 10° S.) and N. 80° E. (E. 10° N.).
THE RELATIONSHIPS OF THE OLENTANGY SHALE
AND ASSOCIATED DEVONIAN DEPOSITS
OF NORTHERN OHIO'
C. R. STAUFFER
The University of Minnesota
In the flat glaciated region to the south and east of Sandusky
there are few outcrops of the older rocks. The drainage is mostly
by small, weak streams which have not yet had time to erode exten-
sive valleys, and railroads have not been compelled to cut deeply
in order to establish their grades. About seven miles south of
Sandusky, however, where the land is a little higher than in the
city and the mantle rock is exceedingly thin, some of the creeks
have exposed small sections of bedrock which are somewhat
exaggerated by a considerable local dip. Two of the more impor-
tant of these are to be found along Plum and Pipe creeks. These
sections have been discussed elsewhere,’ but a recent study of the
region has added some valuable facts to those formerly given and
has made it possible to correlate this Ohio Hamilton with the
Devonian deposits of the same age to the north of Lake Erie.
Plum Creek heads about nine miles southeast of Sandusky and
flows, in a general northerly direction, to the lake. At a point
about two miles east-northeast of Prout station, on the Baltimore
& Ohio Railroad, it cuts into Huron shale, and a little farther north
into the Hamilton beds, exposing the following section:
SECTION OF THE HAMILTON ROCKS AND HURON SHALE ALONG PLUM CREEK
Thickness
Huron Shale Ft. In.
PRM SHAE, BICHDIIGHS DUAR Senin GMC Toile, sia shaw cca nase ante 4 °
Widder Beds
11. Prout or Encrinal limestone. A very hard siliceous blue lime-
stone containing a little chert and much pyrite. Silicified corals
and crinoid stems are abundant, the latter especially in the
WICH Gs FAVORS suey ttre 6,5 0 cee eee aie oleae Fares Ke 8 10
* Published with the permission of the Deputy Minister of Mines, Ottawa,
Canada.
2 Geological Survey of Ohio, Bulletin No. 10, 4th Series, 1909, pp. 119-22, Pls. VIII
and IX.
476
OLENTANGY SHALE AND DEVONIAN DEPOSITS 477
FAUNA
Favosites billingst, Zaphrentis prolifica, Fenestella sp., Atrypa
reticularis, Spirifer sp., Stropheodonta per plana
Olentangy Shale
On SOVELe dsl Lenya oy pyeennpamiastemarit cee s asec sods ode 9 yo vans Geen 6 fo)
FAUNA
Autodetus lindstroemi, Spirorbis angulatus, Streblotrypa hamilto-
nensis, Fistulipora corrugatus ?, Hederella canadensis, Tremato-
spira sp., Chonetes deflectus, Crania hamiltonensis, Leiorhynchus
kelloggt, Leiorhynchus laura, Rhipidomella cyclas, Sprifer mucro-
natus, Stropheodonta demissa, Stropheodonta concava, A ctinopteria
boydi, Aviculopecten fasciculatus, Glosseletina triquetra, Leiopteri
rafinesquit, Muicrodon bellistriatus, Modiomorpha subalata,
Mytalarca oviforme, Pterinea flabellum, Pterinopecten vertumnus,
Schizodus appressus, Tellinopsis subemarginata, Bembexia
sulcomarginata, Cyrtonella mitella, Pleurotomaria capillaria, Or-
thoceras sp., Bairdia devonica, Bollia sp., Bythocypris indianensis,
Primitiopsis punctulifera, Phacops rana, Fish plates
Seolalewargillaceous sort yblucsa ane iens ake c\sciusls sie eter eae 3 6
FAUNA
Chonetes deflectus, Chonetes setigerus, Crania crenistriata,
Leiorhynchus kelloggi, Spirifer mucronatus, Styliolina fissurella,
Bythocypris indianensis
FAmimestone ys Gquite Inara DIMEN tania. so eer: we ce Eee fo) 6
FAUNA
Cystodictya hamilionensis, Trematopora sp., Chonetes deflectus,
Leiorhynchus kelloggi, Leiorhynchus laura, Spirifer mucronatus,
Actinopteria boydi, Platyceras erectum, Phacops rana
GeO ewSOlemOlI Chee a rms cat eiltre Na oe Us aleccteie) om atroeniare ae cmet 5 fe)
FAUNA
Chonetes deflectus, Bythocypris indianensis
5. Limestone, blue, lower part shale, very fossiliferous.......... ° 6
FAUNA
Ambocoelia umbonata, Chonetes deflectus, Leiorhynchus kelloggi,
Stropheodonta demissa, Cypricardinia indenta, Glyptocardia
speciosa, Grammysia arcuata, Grammysia bellatula, Grammysia
bisulcata, Grammysia constricta, Modiomorphia subalata, Nucula
corbuliformis, Nuculites oblongatus, Nuculites triqueter, Nyassa
recta, Pholadella radiata, Schizodus appressus, Bellerophon lyra,
478 C. R. STAUFFER
Pleurotomaria planodorsalis, Pleurotomaria rotalia, Orthoceras
sp., Bairdia devonica, Barchilina sp., Bollia sp., Primitiopsis
punctulifera, Bythocypris punctatus, Phacops rana, Fish plate
4. Shale, argillaceous, soft, blue. This shale contains numerous
small pyrite concretions, some of which are beautifully twinned
crystals. The fossils are probably rare in most of it and appear
to be in streaks or layers:,; Mostly covered .5.... 5. oc o.Neee Io oO
FAUNA
Orbignyella monticula, Leiorhynchus laura, Spirifer mucronatus,
Athyris spiriferoides
3. Shale, blue; with pyritized fossils’) ).0.4.. car oo wate soeuee o. 66+
FAUNA (PYRITIZED)
Leiorhynchus sp., Leda rostellata, Nuculites triqueter, Bactrites
arkonense, Tornoceras uniangulare
2. Shale, blue... Fossilsirather abundant. < .c5 ssi .cdn yc ec ae 3+ o
FAUNA
Alveolites monroei, Aulopora cornuta, Aulopora serpens, Cerato-
pora rugosa, Zaphrentis prolifica, Spirorbis omphalodes, -Acan-
thoclema hamiltonense, Ascodictyon stellatum, Batostomella
obliqua, Fistulipora involvens, Fistulipora spinulifera, Hederella
canadensis, Hederella filiformis, Heteronema monroei, Orbignyella
monticula, Orbignyella tenera, Athyris spiriferoides, Chonetes coro-
natus, Chonetes deflectus, Crania hamiltoniae, Cryptonella plani-
rostra, Cyrtina hamiltonensis, Leiorhynchus kelloggi, Phili-
dostrophia iowaensis, Spirifer mucronatus, Stropheodonta demissa
Tropidoleptus carinatus, Styliolina fissurella, Bairdia devonica,
Primitiopsis punctulifera
1. Shale, soft blue, with some flat calcareous concretions. Fossils
TARO Sie cp ss ais 8 Wale cree Ree RIN RRR reece Seat re 5+ o
The other important Ohio outcrop is along the south branch
of Pipe Creek, one-fourth mile east of Bloomville and about three
miles west of the one just given on Plum Creek. At that point
the Prout limestone has been quarried to a limited extent, and is
therefore well exposed, although the beds of shale below are pretty
well sodded over.
SECTION OF THE HAMILTON BEDS ALONG SOUTH BRANCH OF PIPE CREEK
Widder Thickness
Beds Ft. In.
4. Prout or Encrinal limestone. An impure blue limestone some
layers of which are very crinoidal and the upper one containing
TALE MAUMIGLOUS CORAIS saci otto iete cer Aes wer< Gisle ex cle ner 9 °
OLENTANGY SHALE AND DEVONIAN DEPOSITS 479
FAUNA
Baryphyllum verneuilanum, Cladopora canadensis, Cladapora
roemert, Cystiphyllum vesiculosum, Favosites alpenaensis, Favo-
sites billingsi, Favosites placenta, Favosites radiciformis, Fav-
osites turbinatus, Heliophyllum halli, Syringopora intermedia,
Zaphrentis prolifica, Polypora; sp., Atrypa reticularis, Athyris
vittata, Chonetes mucronatus, Chonetes scitulus, Rhipidomella
vanuxemt, Schizophoria striatula, Spirifer audaculus macronotus,
Spirifer mucronatus, Stropheodonta demissa, Platyceras erectum,
Phacops rana
Olentangy
Shale
3. Shale, blue, alternating with blue argillaceous limestone; very
poorly exposed but weathered blocks of the limestone lie on the
steep bank and numerous fossils have weathered out of the
SOLLCTMMANVICES ep intesrs ema airs HueinMerumtareeriscern tM uN 2 MaMa I5= o
FAUNA
Ceratopora rugosa, Zaphrentis prolifica, Spirorbis, angulatus,
Spirorbis omphalodes, Acanthoclema hamiltonensis, Batostomella
obliqua, Botryllopora socialis, Cystodictya hamiltonesnsis, Fis-
tulipora spinulifera, Hederella filiformis, Orbignyella monticula,
Polypora sp., Ambocoelia umbonata, Atrypa reticularis, Chonetes
deflectus, Chonetes scitulus, Crania hamuiltonensis, Cryptonella
planirostra, Leiorhynchus laura, Rhipodomella cyclas, Schizo-
phoria striatula, Spirifer mucronatus, Stropheodonta demissa,
Fish plate
2. Shale, marly, blue, badly weathered and soil-covered........ Io oOo
1. Shale, blue, with disk-like blue limestone concretions......... 5+ 0
The lower part of the shales in these sections is apparently not
very fossiliferous. ‘The same is usually true of the Lower Hamilton
of Ontario and in many places of the similar deposits in New York.
This is probably even more characteristic of the Olentangy shale in
central Ohio. However, at Delaware, Winchell’s type section
of the Olentangy, a few poorly preserved fossils' were found which,
although only given’ generic identification, are believed to be
identical with others found in the shales of the Sandusky region.
It was at Delaware also that the crinoid bed was found in the
Olentangy shale—a lens corresponding in every way with the
thin lenses of crinoidal limestone common in the lower shales of
t Geological Survey of Ohio, Bulletin No. 10, 4th series, 1900, p. 89.
480 C. R. STAUFFER
the Hamilton beds exposed along Aux Sable River in Ontario. The
general make-up, appearance, and physical properties of the shale
below the Prout limetsone and the Olentangy shale are the same
(Figs. 1, 2, and 3). Moreover, the Delaware limestone, which
underlies this deposit at Delaware and at Sandusky, carries the
Fic. 1.—A weathered bank of fossiliferous Olentangy shale showing one of the
common calcareous layers in this shale along Plum Creek, near Prout station.
Fic. 2.—A bank of Olentangy shale along the Olentangy River at Delaware,
Ohio. The limestone disks in this bank contain an occasional fragmentary fossil.
The lens of crinoidal limestone was found at this locality. This is Winchell’s type
locality for the Olentangy shale and shows its marked contrast to the Ohio or even to
the blue bands occurring in the middle portion of the latter.
same fauna at both places and extends northward into Ontario.
Whitfield found the lower part of the Delaware to be the western
extension of the Marcellus shale, to which he considered it to be in
part equivalent. Wherever the Delaware limestone becomes
™R. P. Whitfield, Proceedings of the American Association for the Advancement of
Science, XXVIII (1879), 208.
OLENTANGY SHALE AND DEVONIAN DEPOSITS 481
especially shaly, as is often the case, the fauna tends to revert to
that of the more typical Marcellus, so that these forms are not
limited to the basal portion. But the occurrence in it of certain
fossil forms more characteristic of the true Hamilton beds of New
York than of the Marcellus of that region has led to the use of
Marcellus-Hamilton or Lower Hamilton for the Delaware. In
this use of the Hamilton, it is the older and broader sense of that
term, rather than the restricted present usage, that was intended.
It would more properly be called the lower Erian. The Olentangy
Fic. 3.—A bank of Olentangy shale downstream a short distance from the one
illustrated in Fig. 2.
shale is overlaid by the Ohio shale in the central part of the state
and by the Huron or lower Ohio shale at Sandusky. ‘The strati-
graphic position of the blue shale in question, therefore, suggests
the same correlation that has been made on the meager fauna and
the lithological similarity. When it is recalled that the regions
in question lie within the same Devonian basin and that the deposits
are a continuation of the same general line of Devonian outcrops,
traceable by well-records in the covered interval between, this
relationship seems worthy of consideration.
The relation of the Sandusky deposit to the Hamilton beds of
Ontario is much more easily determined. In a memoir on the
Devonian of southwestern Ontario, which was recently published by
the Geological Survey of Canada, the correlation of the shale below
the Prout limestone with the Olentangy has been adopted, and the
482 C. R. STAUFFER
Hamilton beds have been divided, in descending order, into the
Ipperwash limestone, the Petrola shale, the Widder beds, and
the Olentangy shale. In the sections at Arkona, Lambton County,
the two lower stages are well exposed. At no place in the province
is the bottom of the Olentangy shale exposed, although well-
records indicate that it rests directly upon the Delaware limestone.
This latter formation is well shown in the excellent outcrops at
St. Mary’s and at several places in the vicinity of Brussels and
Goderich. In the following section of the Hamilton beds in Rock
Glen at Arkona, only the fauna of the Encrinal limestone and of the
beds below are given, since the subsequent comparison is made
with those portions of the section only."
SECTION OF THE HAMILTON Rocks AT ARKONA, ONTARIO
Widder Thickness
Beds Ft. In.
ri. Soil and drifts os5 (eo ie eee res Ne eee Cee 15 °
1o. Limestone, argillaceous, massive, blue, partly cystalline, alter-
nating with thin layers of shale. These beds form the falls at
the ‘old:mill’.. oko sek se ree eee ee ene Secret ree 10 8
g. Shale, soft, blue, with calcareous nodules or concretions...... 8 4
8. Limestone, argillaceous; blues.5,.a. 13Scas000 525 260s. 0 seek I 6
7. Shale, usually soft, blue, but some layers harder and more
THASSEVE 2.55 Sh ORS Ses retort rea eI eck ee ah eae 17 5
6: ‘Shale.and shaly ‘blue limestones 2-3 jr se 52 sae Seles sk wees 7 °
5. Coral zone. A decomposed blue or gray shale, often an impure
shaly limestone, filled with corals’). ..00i. 2.02. s oeee eects 3 6
4. Encrinal limestone. A hard, pyritiferous, bluish-gray limestone
which is full of crinoid segments, coral fragments, and other
fossils. It includes some brownish shale near the base....... 2 4
FAUNA
Aulopora serpens, Ceratopora dichotoma, Cladopora canadensis,
Cladopora roemeri, Craspedophyllum archiaci, Cystiphyllum
vesiculosum, Favosites alpenaensis, Favosites placentus, Favosites
turbinatus, Heliophyllum halli, Syringopora intermedia, Syringo-
pora nobilis, Trachypora elegantula, Zaphrentis prolifica, Dola-
tocrinus liratus, Hederella filiformis, Streblotrypa hamiltonensis,
Taeniopora exigua, Ambocoelia umbonata, Atrypa reticularis,
Athyris vittata, Chonetes coronatus, Chonetes lepidus, Delthyris
« The fauna of the other beds may be found listed in the Geological Survey of Canada
Memoir (No. 34, p. 164), on the Devonian of southwestern Ontario.
OLENTANGY SHALE AND DEVONIAN DEPOSITS 483 |
sculptilis, Leiorhynchus laura, Pholidops hamiltoniae, Pholido-
strophia iowaensis, Productella productoides, Rhipidomella
penelope, Rhipidomella vanuxemi, Schuchertella perversus,
Spirifer divaricatus, Spirifer mucronatus, Stropheodonta concava,
Stropheodonta demissa, Stropheodonta perplana, Pterinea flabel-
lum, Platyceras erectum, Tentaculites bellulus, Phacops rana
Olentangy
Shale
3. Shale, soft, gritless, blue, containing few fossils except in certain
SELEAKSHOLMAV EES ero nameatia | Cormtara ge acs ed Mic veh airine, aie 19 °
* FAUNA
Microcyclas discus, Arthracantha punctobranchiata, Chonetes
lepidus, Pholidostrophia iowaensis, Platyceras erectum
2. Shale, soft, gritless, blue, with a few thin lenses of very fossilif-
erous crinoidal limestone. These beds include a thin zone in
which the fossils are small and always pyritized............. 6 °
FAUNA (PYRITIZED)
Leda rostellata, Nucula lirata, Nuculites triqueter, Paracyclas
lirata, Bactrites arkonensis, Tornoceras uniangulare
FAUNA (NON-PYRITIZED)
Arthracantha punctobranchiata, Gennaeocrinus arkonensis
Palaeaster eucharis, Chonetes deflectus, Chonetes lepidus, Chonetes
scitulus, Cyrtina hamiltonensis, Parazyga hirsuta, Productella
spinulicosta, Schuchertella perversus, Spirifer mucronatus,
Actinopteria boydi, Glypodesma erectum, Bellerophon triliratus,
Platyceras erectum, Platyceras rarispinosum, Platyceras sub-
spinosum, Pleurotomaria delicatula, Styliolina fissurella,
Tentaculites attenuatus, Tentaculites bellulus, Primitiopsis
punctulifera, Phacops rana
1. Covered interval to the level of the Ausable River.......... sie) °
The most important point of similarity between the Ohio and
Ontario sections is to be found in the fauna of the thin layer about
25 feet below the base of the Prout limestone, and at a similar dis-
tance below the Encrinal limestone of Ontario. In both cases
the fossils are pyritized and of small size. Although the fauna of
this layer is somewhat more limited in Ohio, the four species that
have been found in it are identical with those of the similarly
located layer of the Arkona section. At no other horizon has this
fauna been found in Ohio, and three of the species have not been
484 C. R. STAUFFER
found outside of it in Ontario, and even the fourth but sparingly.
It seems certain, therefore, that this is the same horizon in both
cases. From the prominence of Bactrites arkonensis in this layer
at Arkona and Sandusky, it may be termed the Bactrites horizon.
The question next arises as to the relationship of the beds above
the Bactrites horizon. In the Sandusky region the fossils of this
portion of the formation seem to be more abundant in certain
streaks or beds. To a limited extent the same is true of the shales
below the Encrinal limestone in Ontario, but there the great body
Fic. 4.—The Prout or Encrinal limestone overlain by the Huron shale at Slate
Cut along the Lake Shore and Michigan Southern Railway three miles east of San-
dusky, Ohio.
of the deposit between the Bactrites layer and the Encrinal lime-
stone is very sparingly fossiliferous. The Encrinal limestone may
be described as several layers of a hard, pyritiferous, bluish-gray
limestone which is often full of crinoid fragments—a description
which fits equally well the Prout limestone (Fig. 4) in the sections
here under consideration and especially the middle layers at
Bloomingville. Along Eighteen Mile Creek, New York, one of the
important fossils of the Encrinal limestone is Delthyris sculptilis.
Grabau says: ‘‘This species is entirely restricted in this region to
the Encrinal limestone, and may be regarded as the typical fossil
of the fauna.’’' This is also the case in Ontario and probably led
Shimer and Grabau to correlate the limestone in Ontario with
t Bulletin of the Buffalo Society of Natural Science, Vol. VI (1898), 32.
OLENTANGY SHALE AND DEVONIAN DEPOSITS 485
the similar one in western New York,’ although many other forms
are also common to the Encrinal limestone of the two regions.
The fossils in the beds immediately below the Prout limestone
are more abundant than in the shale just below the Encrinal lime-
stone of Ontario. In this respect the northern Ohio deposit shows
more decided relationship to the western New York section. In
fact, the upper part of it includes a portion of the fauna of the
“Demissa bed,” although it lacks Spirifer granulosus and some of
the other prominent forms. However, this suggested relationship
with the New York section is not fully substantiated.
In addition to the marked lithological similarity and strati-
graphic relation of the Prout and Encrinal limestones, over 75 per
cent of the fauna of the Prout limestone also appears in the Encrinal
limestone of Ontario, and the upper layers contain many of the corals
of the coral zone at Arkona, Ontario. It seems reasonably certain,
therefore, that the Prout limestone is the Ohio representative of
the Encrinal limestone to the north and perhaps to the east as well.
At Kettle Point, Ontario, the Devonian black shale rests upon
a limestone of the Hamilton which lies about 150 feet above the
Encrinal limestone, and well-records? show that this is the usual
succession of beds in Lambton County, Ontario. In Middlesex
and Kent counties, which lie to the south of Lambton, this limestone
is sometimes present, but at other places is wanting,’ as might be
the case where erosion has taken place prior to the deposition of
the black shale. The Huron, or basal portion of the Ohio, lies
directly upon the Prout limestone at Sandusky. It therefore either
represents the upper Hamilton shale and limestone of Ontario, or
these deposits are wanting in northern Ohio and the Huron shale
rests unconformably on the Encrinal limestone. On the basis of
the fossils and the occurrence of spheroidal concretions in both
deposits, Kindle has correlated the black shale at Kettle Point,
Ontario, with the Huron shale of northern Ohio.’ If this correlation
t Bulletin of the Geological Society of America, Vol. XIII (1902), 164, 166.
2H. P. H. Brumell, Geological Survey of Canada, Ann. Rept., V, Part Q (1892),
61-70.
3 Ibid., pp. 52, 73, 74-
4 Geological Survey of Canada, Summary Report for 1912 (1914), pp. 287, 288.
486 C. R. STAUFFER
is correct, as seems probable, the Huron shale does not repre-
sent the Upper Hamilton, but rests unconformably on the Prout
or Encrinal limestone.
Mr. Allen R. Stuckey, who has drilled numerous wells in
Crawford and adjoining counties, reports that at Bucyrus’ the
drift ranges from 55 to 80 feet in thickness. Under this is 35 to
200 feet of black shale, which is usually succeeded below by about
10 feet of gray shale, so tough and sticky that it is difficult to drill.
This gray shale immediately overlies the limestone, but in a few
wells it has been found to be absent where the black shale rests
Fic. 5.—The Olentangy-Ohio shale contact at ‘Dripping Rock,” near Liberty
Church, Delaware County, Ohio. Here again there is an undulating contact.
directly upon the limestone. In the eastern part of this county,
30 feet of the gray shale is found at many places. It is evident,
therefore, that in Crawford County the Olentangy shale is even
more variable in thickness than it is in central Ohio and that the
Prout limestone of the Sandusky region has disappeared. At
“Dripping Rock” (Fig. 5), in Delaware County, where the Prout
limestone is wanting and the Olentangy shale is only about 31 feet
in thickness, the contact between it and the overlying Ohio shale
is most marked and slightly undulating. The contact is equally
marked at High Banks, near the Franklin-Delaware county line,
and again in the town of Delaware (Fig. 6). At this latter place
the basal Ohio shale is somewhat arenaceous. Near the Ohio
River, at Kinkead Springs, Pike County, the Ohio extends down
to the Silurian limestone and is firmly welded to it.
OLENTANGY SHALE AND DEVONIAN DEPOSITS 487
Southward from Kettle Point, Ontario, therefore, the Huron or
lower portion of the Ohio shale rests on older and older beds to
which its relationship must be that of unconformity (disconformity).
This relation is not strikingly perceptible at any one place, but in
southern Ohio the time interval between the Silurian and Devonian
strata, which are in contact, is enormous. When it is recalled that
the first effect of running water on a newly uplifted land surface is
to roughen it, and that continued erosion tends to produce planeness,
it is clear that, where little or no folding or tilting of the stratified
rocks has taken place, slight (apparent) unconformities are likely to
Fic. 6.—The sharp and slightly undulating contact between the Ohio and the
Olentangy shales in the clay pit at Delaware, Ohio.
represent great intervals of time, while conspicuous ones may stand
for shorter intervals. Or, in other words, the greater the time inter-
val whichis represented by an erosional unconformity (disconformity)
in undisturbed strata, the more evasive it is likely to be. This is
probably one of the chief reasons for the marked differences in the
interpretation of sections where such gaps in sedimentation occur.
With the Hamilton beds at Sandusky and in central Ohio resting on
the Delaware limestone (Lower Erian) and overlaid uncontormably
by the Ohio shale in both places, the advisability of calling the soft
marly beds to the south of Sandusky, Olentangy shale seems to be
justified, even though the faunal evidence may not be as conclusive
as could be desired.
EVOLUTION OF THE BASAL PLATES IN MONOCYCLIC
CRINOIDEA CAMERATA. I
+ HERRICK E. WILSON
United States National Museum, Washington, D.C.
CONTENTS
PAR EE
INTRODUCTION
ACKNOWLEDGMENTS
REVIEW OF WACHSMUTH AND SPRINGER’S THEORY OF BASAL PLATE
EVOLUTION
REVIEW OF CERTAIN PHYLOGENETIC CHARACTERISTICS IN MONOCYCLIC
CAMERATA :
DETAILED STUDY OF PROCESSES ACTIVE IN PLATE EVOLUTION
1. Changes Not Primarily Modifying the Relations of Plate Contact and
Position
a) Symmetrical Growth
b) Reduction of Parts by Absorption
c) Anchylosis
PARESTE
2. Changes Primarily Modifying the Relations of Plate Contact and
Position
a) Reduction and Compensating Growth
b) Enlargement and Compensating Reduction
c) Plate Division
d) Plate Migration
e) Plate Interpolation
tf) Anchylosis
ANCHYLOsSIS: ITs ANTECEDENTS AND CONSEQUENCES
1. Anchylosis and Reduction
2. Delayed Anchylosis
3. Anchylosis and the Phylogenetic Reappearance of Sutures
DEVELOPMENT OF THE INTESTINE AND THE CONSEQUENT ZONES OF POTENTIAL
WIDENING
ORIGIN OF THE ANAL PLATE
488
BASAL PLATES IN CRINOIDEA CAMERATA 489
PART III
EVOLUTION OF THE BASE IN MoNocycLic CAMERATA
1. Evolution of the Pentagonal Base
2. Theories for the Evolution of the Base in Hexagonal Camerata
a) Enlargement of the Posterior Basal
b) Development of the Quadripartite Base
c) Development of the Tripartite Base
3. Evolution of the Base in the Hexacrinidae
a) Evolution of the Tripartite Base
b) Evolution of the Bipartite Base
4. The Succession of Basal Changes in the Platycrinidae and the Hexa-
crinidae
SUMMARY OF CONCLUSIONS
BIBLIOGRAPHY
PART I
INTRODUCTION
Most students of fossil crinoids have been interested in the
morphological results of evolution rather than in the morpho-
logical processes of evolution and their results, and the description
of extinct, fossil crinoids as well as of most living ones has been in
general a tabulation of those results. In many cases the tabulation
is incomplete, not only because of the rarity and incompleteness
of the specimens described, their poor preservation and sometimes
poorer preparation, but also because the obscure morphological
processes which have given rise to their characteristics are either
overlooked or misinterpreted. The greatest difficulty in estab-
lishing a natural classification lies in the fact that processes giving
rise to morphological characteristics must be known before a cor-
rect interpretation and classification can be made. From necessity
paleontologists are familiar with the obscurity of processes. The
ontogeny of the fossil crinoid is only partially revealed, and that
mostly in the phylogenetic succession, for the delicately constructed
embryos are ill-adapted for preservation, and comparatively few
immature individuals have been preserved. The complete em-
bryonic and larval development of modern crinoids is known only
in one highly specialized genus, Antedon; the larval stages, however,
are partially known in four other genera, Promacocrinus, Thaumato-
crinus, Comactinia, and Hathromeira.
490 HERRICK E. WILSON
Various phases of the evolutional changes in the basal plates of
crinoids have been considered by both paleontologists and zodlogists.
The relation of these plates to the column, their modification by
the anal plate, and their characteristic decrease in number and
size with the passage of geologic time attracted attention long
before the importance of tegminal structure was realized," and
some interesting though unsuccessful attempts have been made to
use basals as a foundation for classification.? Such artificial classi-
fications have been swept away, but the fact remains that the
changes of each plate and system of plates, as they have passed
through the varying stages of evolution, must have classificatory
value. When, where, and from what the monocyclic Crinoidea
originated are questions of great importance, yet not of special
import for the subject as herein discussed. The fact that mono-
cyclic crinoids have existed, that their basal plates exhibit a series
of remarkable changes, and that certain features in their phylogeny
throw much light upon the character of the changes and their
succession, is sufficient for present purposes. The process by
which these changes came about is the problem to be considered
here.
In this paper no attempt at reclassification will be made, but
the changes exhibited by the basal plates will be reviewed, the
nature of these changes studied, and suggestions arising from these
studies will be applied to certain theories of descent that have
arisen from similar studies made by others.
ACKNOWLEDGMENTS
The writer desires to express his sincere appreciation to Professor
Stuart Weller, of the University of Chicago; Mr. Frank Springer,
Mr. Austin Hobart Clark, Dr. E..O. Ulrich, and Dr. R. S. Bassler,
of the United States National Museum; and to Professor R. A.
Budington, Dr. Charles G. Rogers, and Dr. Maynard M. Metcalf,
of Oberlin College, for the material assistance given by them in
the use of specimens and literature, and for a broad view of the
* Ref. 38. (The reference figure is the number assigned to the work cited in the
Bibliography.)
2 Ref. 2; ref. 22.
BASAL PLATES IN CRINOIDEA CAMERATA 491
processes operative in the growth and modification of many groups
of invertebrates.
To Professor Weller, Mr. Springer, and Mr. Clark the writer
is especially indebted for their many kindnesses, their helpful
advice, and the privilege of freely studying their collections of
fossil and recent crinoids.
REVIEW OF WACHSMUTH AND SPRINGER’S THEORY OF
BASAL PLATE EVOLUTION
While various phases of basal plate evolution have been touched
upon by numerous writers, the discussion by Wachsmuth and
Springer’ is the only one in which a general treatment of the sub-
ject has been undertaken, and, in order that the reader may have
their theory clearly in mind before going farther, it will be quoted
in substance.
The base of a monocyclic crinoid is composed of a single cycle
of plates, termed the basal plates, lying at the proximal end of the
cup, between the stem and the first plates of the radial series.
This plate cycle was primarily composed of five separate plates,
but, by anchylosis or the union of two or more members, they were
reduced from five plates to four, three, two, or one. The first
monocyclic crinoids had five basals.
Before the close of the Lower Silurian (Ordovician) there appeared two
monocyclic genera with four basals, both having a special anal plate inter-
posed between the radial. The quadripartite base reached its culmination
in the Upper Silurian (Silurian), and disappeared before the close of the
Devonian. The earliest genera with a tripartite base occur in the Upper
Silurian; some of them have an anal plate, and others not. When that plate
is represented, the basals are of equal size; when absent, two of the basals
are equal, and the third about half smaller. The two forms continue to
exist side by side to the end of the St. Louis group of the Carboniferous (Missis-
sippian) when both became extinct. The bipartite base is restricted to the
Carboniferous (Mississippian and Pennsylvanian). It occurs from the Kinder-
hook group up to the Coal Measures, but is found only among genera with a
large? anal plate.
t Ref. 39, pp. 52-68.
2 The exact meaning of the statement that the bipartite base is found only among
genera with a large anal plate is doubtful, as Pterotocrinus, a genus with a hexagonal
bipartite base, usually has, in proportion to the size of its basals and radials, the
492 HERRICK E. WILSON
It is evident from these observations that the number of basals was gradu-
ally reduced in Paleozoic times, and that in the Camerata the anal plate was
introduced after the quadripartite base had made its appearance. It will
now be shown that this diminution of number was the result of fusion of two
or more of the five original plates, and that by the introduction of the anal
plate the base underwent further modifications. The manner in which the
modifications in the number of basals were effected may be best understood
by reference to the diagrams on Table A. [This table is photographically
reproduced as Fig. 1 of this article.]
Looking at these diagrams, the transmutation in the Camerata from five
basals to a less number is readily understood among genera in which the anal
plate is wanting. When the base is quadripartite, it is invariably the two
anterior plates of the elementary five which are consolidated (2). In the
tripartite base there is a fusion of the posterior with the left postero-lateral
basal, and another between the right posterior and the adjoining antero-
lateral plate (3). The figure shows that a bisection of the two larger plates
will reproduce the original five pieces, interradially disposed.
The case is not so simple in genera with an anal plate, where the form of
the basal disk is changed from pentagonal to hexagonal (4), as a bisection of
smallest anal plate.now known among Camerata in which the anal plate is in
apposition with the base. See Pl. IIT, No. 11, and Ref. 30, Pl. 70, Figs. 2-0.
When preparing figures for this paper from specimens in Mr. Springer’s collection,
with his permission, I overlooked the fact that the dorsal cup of this Species had never
been described or figured. As to this, Mr. Springer has furnished me the following
note:
“When proposing the species Pierolocrinus coronartus (Geology of Kentucky, III,
476, Pl. I, Figs re, 6) Lyon described and figured only the tegmen with the ponderous
wing plates, as did Wachsmuth and Springer after him (V.H. Crin. Cam., p. 795).
While this work was in press I discovered in the Museum of Comparative Zodlogy
at Harvard a lead cast of what was apparently the same specimen, with the dorsal
cup attached, which fact I mentioned in a footnote on the page cited. When I acquired
in 1903 the collection of the late Col. Sidney S. Lyon, I found associated with the
tegmen constituting the published type the dorsal cup reproduced in the cast; the
two parts were separated, but I have again united them. It is probable that they
belong to the same specimen, and the fact that they pertain to the same species is
proved beyond question by another specimen from the same locality having the same
dorsal cup with one of the wing plates attached. The species is remarkable, not only
for its extraordinary wing plates, but also for the construction of the dorsal cup, in
which the basal plates are very small and flat, while the radials are of enormous size,
larger than all the other plates of the cup combined; this being the reverse of the
structures in Pt. capifalis and all other known species of the genus. It occurs in the
Birdsville formation of the Kaskaskia group, in Crittenden County, Kentucky, where
it is extremely rare; and also in the Renault formation in Monroe County, Illinois,
from which region a fragmentary specimen was described by Hall (Geol. Towa, IT, 689,
Pl, XXV, Fig. 7) under the name Dichocrinus protuberans.”
BASAL PLATES IN CRINOIDEA CAMERATA 493
the larger plates would produce six plates instead of five. This difficulty,
however, is overcome if we consider that the introduction of the anal plate
into the ring of radials necessitated corresponding modifications among the
basals, as otherwise these plates would lose their interradial position. It
3 4
Ichthyocrinidg. Tehthyocrinidas
18
Rhodocrini a 6
ocrinide. Thysanocrinide Apiocrinides (yonng). Apiocrihidw (adult)
Fig. 1.—Diagrams illustrating the evolution of the basals and infrabasals: all
figures represent the anal side at the top; @=posterior basal; b and e=postero-lateral
basals; ¢ and d=anterior basals; f, g, h, 7, k=infrabasals.
required either the introduction of a basi-anal plate, or an increase in the size
of the original pieces. That the latter occurred among the Camerata is clearly
shown by the diagrams, and the evidence leaves no doubt at what part of the
base the extra width was inserted.
404 HERRICK E. WILSON
Taking first the quadripartite base, and comparing 2 of the diagrams with
8—one pentangular, the other hexangular—we find that in the latter the
posterior basal has doubled in size (7), without materially changing the orien-
tation of the plates, or disturbing their general arrangement. ... .
In the tripartite base the change was accomplished in a different way.
There x is added to plate c (9 and 10), and plates ab and ed have coalesced,
and hold relatively the same position as in 3.
The bipartite base is probably derived from the tripartite (4), which pre-
ceded it in time, and x, which in the latter constituted a part of c, is united
with de, and ab with c (11 and 12).
Now taking up 7 and eliminating x, so that the side of plate a rests against
the plate e, we obtain 2, and by a similar procedure we are enabled to trans-
form g into 3. The hexagonal base is thus restored to its primitive pentagonal
form without disturbing the orientation of any plate, compound or simple.
This theory was thought by Wachsmuth and Springer to have
been confirmed by an abnormal example of Teleiocrinus umbrosus
n which the anal plate was wanting.
Teleiocrinus umbrosus has normally three equal basals, but in this specimen
the basal plate to the left of the anterior ray is reduced to one-half its normal
size, leaving the basal disk exactly like that of forms which are normally
without the anal plate.
It is very remarkable that while in all crinoids with an unequally tripartite,
monocyclic base, the smaller plate is located to the /eft of the anterior radial,
this plate in the base of the blastoids lies invariably to the right (6).
In the discussion of the changes from the pentagonal, five-basal
form to the hexagonal, four-basal form, it is stated that the enlarge-
ment of the posterior basal took place upon the right side of that
plate, but no evidence is submitted for this statement. Why
could not the enlargement have taken place as well upon the left
side, or by symmetrical development upon both sides of the pos-
terior basal? The statement that ‘“‘the evidence leaves no doubt
at what part of the base the extra width was inserted” is not sufh-
cient, and it in itself creates a doubt. Again we are told that “the
introduction of the anal into the ring of radials necessitated cor-
responding modifications among the basals, as otherwise these
plates would lose their inter-radial position.’ However, in the
discussion of the basals in dicyclic crinoids the statement is
made that ‘“‘the introduction of the anal plate into the ring of
TRef. 39, p: 50:
BASAL PLATES IN CRINOIDEA CAMERATA 495
9
radials did not affect the basals of dicyclic crinoids” in the same
manner as in the monocyclic. While in the latter, when the plate
is represented, the orientation of the basals is slightly disturbed,
in the dicyclic forms it remains unaltered. The anal plate of the
latter rests invariably upon the trunkated upper face of the pos-
terior basal; while in monocyclic crinoids it is supported by the
basals a and e (Nos. 1o and 12), or occasionally by a and x (No. 8).
This statement leads one to believe that no widening of the
posterior basal took place upon the introduction of the anal plate
in the dicyclic form, but Nos. 15-18 in Fig. 1 show a decided widen-
ing of that plate. Overlooking this inconsistency and the fact that
trunkation of the posterior basal is in itself an alteration, we are
still unenlightened as to why alteration is demanded in the one
case and not in the other, as no explanation of an alternative
phenomenon is given. Neither is any reason given, other than the
position of sutures, for the markedly different positions of enlarge-
ment in basal plates of the four-, three-, and two-basal hexagonal
forms. By reading between the lines one is able to supply various
explanations, yet they are not the explanations of the writers, nor
what is needed and demanded by the conditions of the problem.
Furthermore, no reasons nor illustrations are given showing why
the abnormal specimen of Teleiocrinus umbrosus, by which the
theory was apparently confirmed, was oriented with the smaller
basal in the left.anterior interray. The questions in the writer’s
mind are: Why should the stimulus of enlarging the anal area in
the quadripartite form cause enlargement of the right side of the
posterior basal and not of the left or of both sides as well? Why
should the same stimulus in a dicyclic crinoid have no effect upon
the adjacent basal plates? Why should the same stimulus cause
the enlargement of the left anterior basal in the equibasaled, tri-
partite form, and of the left side of the right anterior basal in the
equibasaled, bipartite form, derived therefrom? What was the
nature of the change in shifting factor x from basal c to basal d?
How could such changes take place without disturbing the orien-
tation of any plate, compound or simple? What were the reasons
for the orientation assigned to the abnormal specimen of Teleio-
crinus umbrosus ? These questions have led the writer to investigate
496 . HERRICK E. WILSON
the evolution of the basal plates in the monocyclic Crinoidea,
and the result of this investigation will be stated in the latter part
of this study. .
REVIEW OF CERTAIN FHYLOGENETIC CHARACTERISTICS IN
MONOCYCLIC CAMERATA
In this review the phylogenetic characteristics of the various
groups of monocyclic Camerata will be considered, for it is in this
order that the succession is better understood and that the evolution
of the basal plates is the most complex. There exist in this order
two great groups, separated structurally but not phylogenetically
according to the outline of the basal cup, and therefore according
to the presence or absence of an anal plate in contact with and
trunkating the posterior basal. The first of these groups possesses
an anal plate in apposition with the posterior basal, and has in
consequence a hexagonal basal. The second group, in which plates
of the anal series are either present or absent but not in contact
with the posterior basal, has a pentagonal base. In considering
these facts, questions of descent and relationship necessarily arise.
In the ontogenetic development of the external skeleton in the
living Antedon' so many of the phylogenetic steps found in fossil
crinoids are illustrated, that it may well be looked upon as a key
to their methods of development and perhaps to their interrelation-
ships. Leaving out of consideration the earlier embryo-logical
stages, let us follow in detail .the methods of plate intercalation
and development after the formation and contact of the basal and
oral plates (Fig. 2).
About the time of the attachment of the pentacrinoid larva,
the basal plates assume a regular, trapezoidal outline, the lower
part of each being an acute-angled triangle with its apex distally
directed (Fig. 2, No. 1). The sides of the lower triangle are bor-
dered by a somewhat thickened edge of solid, transparent stereom,
the presence of which indicates that the plate has received its full
proportionate increase in that direction.?, Even after the plate
t Antedon, while more highly specialized in its larval development than some of
the other modern crinoids, is chosen for comparison with the Camerata because it is
the best known of any of the genera in which the larval development has been studied.
2 Ref. rr, p. 720-
BASAL PLATES IN CRINOIDEA CAMERATA 497
edges are thus defined, the plates steadily increase in size, appar-
ently by interstitial growth.t The adjacent borders of the plates,
however, do not come into absolute contact, as a thin lamina of
sarcode is interposed between them until the sutures are closed by
anchylosis. The upper margins of the basals have at this time no
distinct border,” but are still growing by the process of branching
and anastomosis (see p. 501, plate growth).
Fic. 2.—Formation of the dorsal cup and migration of the anal plate in Antedon
rosaceus: 1, 2, after Thomson; 3-5, after Carpenter; 6, original from specimen in
Oberlin College Museum; o=orals; 6=basals; r=radials; a=anal.
Shortly after the fixing of the pentacrinoid and the opening of
the cup, a third series of plates, the radials, make their appearance
in the space left by the beveling off (absorption) of the adjacent
lateral angles of the basals and orals (Fig. 2, No. 2),3 the beveling
being caused apparently by the encroachment of the radials.4 About
the period of the development of the second radials (costals) a
forked spicule makes its appearance between the upper parts of
the posterior radials. This plate gradually increases in the regular
t Interstitial growth: ref. 35, p. 538. 3 Ref. 35, p. 530.
2 Ref. 11, p. 720, Pl. 41, Fig. 1, 0. 4 Ref. 11, p. 720.
408 HERRICK E. WILSON
way (see p. 502), until it develops into a round, cubiform plate, the
anal plate (Fig. 2, No. 3).1_ The radials, with the anal plate between,
now form nearly a complete circle, resting on the basals and sepa-
rating them completely from the orals.?,- Although greatly enlarged,
the radials are still subquadrangular in outline, the proximal angle
occupying the enlarged portion of the interbasal suture, and the
distal angle, now trunkated, supporting the narrow costals.3 Con-
siderable space still exists between the adjacent radials, except
where they are in apposition with the anal plate (Fig. 2, No. 4),
and these spaces are filled only with sarcodic substance. The anal
plate from proximal growth now comes into apposition with the
posterior basal, and the two are mutually trunkated. Upon fur-
ther development the radials meet, and their margins assume the
finished appearance previously noted in the proximal portion of
the basal plates. The posterior radials, especially the right, how-
ever, show marked asymmetry, owing to the non-development of
the sides adjacent to the anal plate (Fig. 2, No. 5). Growth in
the radials does not cease upon their meeting, and as the basals
do not now further enlarge, the radials and the anal are forced by
contact with each other to extend themselves in an oblique direc- —
tion, thus enlarging their distal perimeter, and increasing the
diameter of the tegmen.
The anal plate by this time has reached its full development
and, being more firmly attached to the visceral mass than to the
adjacent radials,5 is gradually lifted out of the cup by the extension
of the anal tube. The space left by the withdrawal of the anal is
gradually filled by lateral growth from the adjacent radials, which,
however, do not immediately come into contact. Before the anal
is completely withdrawn from the radial cycle, however, the pos-
terior radials meet below it, and, as withdrawal continues, cor-
responding and continuous enlargement of the radials fills the
re-entrant angle, and gives to the plates their bilaterally sym-
metrical outline (Fig. 2, No. 6).
About this time a very remarkable change takes place in the
tegmen. The oral cycle, like the basal one, does not partake of
* Ref. 35, p. 529 (anal). 3Ref. 11, p. 720.
2 Ref. 15, p. 314 (radianal). 4 Ref. 11, p. 729. SRef. a ipayse
BASAL PLATES IN CRINOIDEA CAMERATA 499
the pronounced enlargement noted in the radial cycle, its diameter
being neither increased by growth of its component parts nor
augmented by their separation from one another; but, as the
ventral disk expands, the orals become separated from the radials
upon which they were previously superimposed and are carried
upward and relatively inward and the costals and lower distichals
are incorporated into the cup. The space now existing between
the radials and orals generally remains as a simple, membranous
perisome, traversed by the five ambulacral canals; but, in some
specimens of Antedon rosaceus,’ and in other modern crinoids,
well-defined groups of interradial plates develop in the angles
between the brachials. When these plates appear in the cup they
are known as interbrachials, and in the tegmen as interambulacrals.
Further tracing of the development of the basals and the orals
and consideration of stem formation are not here necessary,
although they may at times be referred to in the following dis-
cussion. ;
In tracing the phylogeny of the Batocrinidae and Actinocri-
nidae, the anal plate is found as a constant characteristic and
the base throughout the series is hexagonal. Complete incorpora-
tion of the ambulacral grooves has taken place in the tegmen, and
the arms are incorporated in the cup up to and often beyond the
second distichals. In Tanocrinus, a genus probably closely related
to the ancestors of the Batocrinidae,? five basals are present; the
anal plate separates the posterior radials, and is in apposition with
and trunkates the posterior basal.
In Xenocrinus, Comprocrinus, and Abacocrinus only four basals
are present, the anterior pair being obviously united and somewhat
reduced in width. In the other genera of the Batocrinidae and
Actinocrinidae there are three equal basals, the basal sutures meet- -
ing the antero-lateral radials and the anal plate. Why the third
basal suture meets the anal plate will be considered later (Plate III).
The Melocrinidae, while not showing as complex a basal evolu-
tion as that shown in the hexagonal Camerata, are interesting in
showing the absence of an anal plate in contact with and trunkating
the posterior basal, and in some genera an absence of all plates of
t Ref. 35, p. 540. Rete On ps LOA:
500 HERRICK E. WILSON
the anal series. The base throughout this family is pentagonal,
and the basals number either five, four, three, or one. When five
basals are present the basal sutures meet the radials in the normal
manner. When four basals are present either the anterior or left
anterior suture is missing, and when only three basals are present
the sutures meet the anterior, left-anterior, and right-posterior
radials.
The Calyptocrinidae have throughout a pentagonal base and
only four basal plates, and the anal plates are entirely missing.
In considering these families the question arises as to whether
the base has been pentagonal throughout its whole phylogenetic
history or whether there has been a hexagonal stage, as in the
Batocrinidae and Actinocrinidae.
The Platycrinidae and Hexacrinidae are characterized by having
the ambulacral grooves and lower brachial plates but slightly
incorporated in the calyx. The orals in the simpler forms are well
developed, and the base is either pentagonal or hexagonal. In
the Platycrinidae ‘no anals have been positively determined, and
the base is pentagonal. Throughout this group there are ordinarily
but three basals, five in youth and sometimes but one in age.
Two of the basals are large, the third smaller. In the Hapalo-
crinus,* the smaller basal is the right-anterior one, and the basal
sutures meet the anterior, right-anterior, and the left-posterior
radials, as in Stephanocrinus. In the other genera of Platycrinidae
the left-anterior basal? is the smaller, and the basal sutures meet
the anterior, left-anterior, and right-posterior radials. In the
Hexacrinidae there are usually three, or two, equal basals, some-
times only one. The base is hexagonal and the anal plate well
developed. The basal sutures in the three-basal forms meet the
antero-lateral radials and the anal plate; in the two-basal forms
the sutures meet the anterior radial and the anal plate.
A discussion of the monocyclic Inadunata as a whole cannot
now be undertaken, but certain species of Larviformia which in
their development illustrate very clearly, even diagrammatically,
t Ref. 21, pp. 94-110.
? Exceptions are noted on p. 507 in the description of Fig. 5, No. 6.
3 Ref. 6, p. 158.
BASAL PLATES IN CRINOIDEA CAMERATA 501
some of the slighter morphological changes found in the Camerata
will be considered in the discussion of morphological principles.
Having noted the more conspicuous changes through which
the basal cup has passed, a detailed study of the processes involved
in these may be undertaken.
DETAILED STUDY OF PROCESSES ACTIVE IN PLATE EVOLUTION
The processes active in the evolution of crinoid plates, especially
the basals and radials, may be divided into two broadly separated
though often co-operating groups: (1) those which do not necessarily
modify the relation of contact and position of the plates; and (2)
those which do modify these relations. The discussion of the first
group of processes includes: (a) symmetrical growth; (0) sym-
metrical reduction; and (c) anchylosis. The second group includes:
(a) reduction and compensating growth; (b) enlargement and
compensating reduction; (c) plate division; (d) plate migration;
(e) plate interpolation; and (/) anchylosis.
I. CHANGES NOT PRIMARILY MODIFYING THE RELATIONS OF PLATE
CONTACT AND POSITION
a) Symmetrical growth—Plate growth in the Echinoidea and
Crinoidea’ is due to the deposition, by amebod cells, of crystalline
calcium carbonate, or calcium and magnesium carbonate’ in re-
ticulate pattern in the mesenchyme. Three, or perhaps more, of
the ameboid calciferous cells fuse by means of pseudopodia into a
plasmodium or reticulate tissue. There the pseudopodia meet,
the protoplasm forms a small calcareous nodule (intracellular secre-
tion, according to Theel; extracellular, according to Semon), which
gradually increases along the pseudopodia, forming a triradiate
spicule. By further branching and anastomosis, the branches of
the spicule meet and fuse at the tips of their processes (Fig. 3,
No. 3), thus building up a hard tissue (stereom), showing a strongly
t Although no observations have been made upon the early details of plate deposi-
tion (stereom formation) in the Crinoidea, the growth of the plate from the primary
spicule on so closely parallels that in the Echinoidea that there can be no doubt con-
cerning the method of formation.
2 Composition of crinoid skeletons: ref. 25, p. 31; ref. 14, p. 488; ref. 17.
- 3Stereom formation: ref. 34.
502 HERRICK E. WILSON
reticulated structure (Fig. 3, No. 4) when sectioned in any direc-
tion. The co-ordination of deposition is such that each plate acts
optically and mineralogically as a single crystal of calcite, without
other planes of weakness than the cleavage planes developed by
crystallization. The margins of the plates are at first rough with
sprouting spicule branches (Fig. 2, No. 2, R), but later, upon
coming into mutual contact, become smooth (Fig. 2, No. 5).
Growth by branching and anastomosis gives way to interstitial
growth,’ and the increase in size is more gradual. Each plate, as
Fic. 3.—Stereom formation: 1, formation of the triradiate spicule by the fusion
of seven calciferous cells; 2, basal from a larva of Antedon on the sixth day; 3, basal
on the tenth day; 4, ideal representation of regular, reticulate stereom. (1, after
Theel; 2, 3, after Bury; 4, after P. H. Carpenter.)
it now enlarges, is carried relatively outward and away from-the
adjacent plates, and in the basal cycle not only away from the
adjacent plates, but also away from the axial canal, as is shown
by growth lines whenever present. When growth of the plates
is symmetrical, each plate in a cycle is the equivalent in size and
shape of every other plate in that cycle, and has the same angles
with reference to the central axis of the cup as the other plates in
the cycle.
b) Reduction of parts by absorption —This also is a function of
ameboid cells, which are similar in appearance to the calciferous
PURGE IS, Db beter
BASAL PLATES IN CRINOIDEA CAMERATA 503
cells, but take the calcareous salts into solution and transmit them
to the deposition cells... When reduction by proximal or distal, or
proximal and distal, absorption is symmetrical throughout a cycle
of plates, the relation of parts is not disturbed, unless the reduction
Fic. 4.—Stereom absorption; absorptive cells operating upon the posterior end
of a calcareous rod in a mature pluteus: 1, one portion of rod separated, the second
partially cut; 2-4, advancing stages up to the nearly completed absorption of portion
one, the separation of portion two (after Theel).
of the cycle is complete, thus bringing previously separated cycles
into apposition with each other.
c) Anchylosis—Anchylosis is the uniting of apposed plates by
an unbroken deposit of stereom in the sutures, and is, as far as we
know, an ontogenetically repetitive process, taking place only
*Ref. 34, pp. 349-351.
504 HERRICK E. WILSON
between plates and not between their formative cell groups. The
intrasutural deposit is formed through the activity of the ameboid,
calciferous cells, and the firmness with which the plates are united
depends upon the amount of stereom deposited. In youth the
deposit is slight, the plates are easily separated, and the sutures
are usually discernible as external or sometimes as internal grooves.
In age, however, much variation exists, for the extent of deposition
depends upon the stage of development reached by the group and
upon the vitality of the individual. In some cases immature (in-
complete) anchylosis is apparently an adult characteristic and the
plates are easily separated.t In other cases the deposit is as strong
as the stereom of the plates, and fracturing results as readily in
the plates as in the old suture plane. Again, in cases where firm
union is the rule, as in the Camerata, lowered vitality, or other
physiological disturbance, sometimes results in the partial or total
inhibition of anchylosis. Such abnormalities, or reversions, are of
great value in determining the position of sutures otherwise un-
traceable, and will be more fully considered under the topic of
delayed anchylosis.
From the foregoing definition of anchylosis the conclusion is
drawn that any suture or group of sutures appearing in the primitive
basal cup may be lost through anchylosis, and the following dis-
cussion will show the actual and possible combinations due to simple
anchylosis alone.
In order to facilitate this description and the tabulation of the
variations to be cosidered, the convention of lettering the basal
plates from the posterior to the nght-posterior, in an anticlockwise
direction, has been adopted, the letters separated by dashes
making up the basal formula. The letters from @ to e denote
the plates and the dashes the intervening sutures; a dash over a
letter shows trunkation of that plate, while the absence of a
dash between the letters denotes the absence of the suture between
those plates. Thus, a—b—c—d—e— is the formula for the simple,
pentagonal base while a—b—cd—e— shows a hexagonal base with
the posterior basal trunkated and the anterior pair of basals
united.
Ref. 1, p. 20; ref, 10;'pp- 36, 37-
BASAL PLATES IN CRINOIDEA CAMERATA 505
From a study of Figs. r and 9g it will be seen that eight types of
basal modification, by the reduction in number of the basal plates,
occur in the Camerata during the Paleozoic era. The primitive
base (a—b—c—d—e—), Fig. 1, No. 1, appears in the Ordovician,
but it probably originated long before that time. The four-basal
type (a—b—cd—e—), Fig. 1, No. 2, appears in the Ordovician,
becomes abundant in the Silurian, and disappears before the close
of the Devonian. The three- inequi-basal type (ab—c—de—),
Fig. 1, No. 3, makes its appearance in the Ordovician, increases in
the Silurian, reaches its climax in the Devonian, and disappears
in the Mississippian. The three- inequi-basal type (ea—bc—d—),
Fig. 1, No. 6, is present during the Silurian, Devonian, and Missis-
sippian, but never becomes very prominent. The one-basal type
(abcde), Fig. 1, No. 5, occurs at various times during the Paleozoic
period, but not as a generic or specific characteristic. The hexag-
onal, five-basal type (a—b—c—d—e—), Fig. 9, No. 6, is present
in the Ordovician. The hexagonal, four-basal type (a—b—cd—e—),
Fig. 1, No. 8, appears first in the Silurian (Richmond) and dis-
appears during the Silurian. The three- equi-basal type (al—ca—
de—)', Fig. 1, No. 10, appears in the Silurian, increases in the
Devonian, reaches its climax in the lower part of the Mississippian,
and then disappears. The two- equi-basal type (abc—a«de—),'
Fig. 1, No. 12, 1s introduced in the Kinderhook and becomes extinct
in the lower part of the Pennsylvanian.
Possible combinations of the primitive five-basals: Since
Wachsmuth and Springer have assumed that all crinoids having
an unequally tripartite base have the smaller basal in the left-
anterior interray, it may be well to consider what combinations
may be expected from anchylosis of the primitive five-basals.
These combinations are explained below and illustrated in Fig: 5.
Fig 5, No. 1, illustrates the primitive basal cup of pentagonal out-
line, represented by the formula a—b—c—d—e—, and found in
Glyptocrinus, Schizocrinus, Stelidiocrinus, and young individuals
of Platycrinus.
Fig. 5, No. 2, shows a common Ordovician and Silurian type of
reduction (a—b—cd—e—), in which the two anterior basals are
t Formula based upon Wachsmuth and Springer’s theory.
506 HERRICK E. WILSON
anchylosed. In this group there are five possible combinations:
ab—c—d—e—, a—bc—d—e—, a—b—cd—e—, a—b—c—de—, and’
ea—b—c—d—. Of these combinations, a—b—cd—e— has been
the only one described in the four-basal Melocrinidae; however,
the writer has found the a—bc—d—e— (No. 2a) combination in
the following specimens in the Springer collection: of eight speci-
mens of Melocrinus calvini from Calloway County, Missouri, four
©oe@
2ee
Fic. 5.—Diagrams illustrating types of the possible combinations due to anchylosis
of two or more of the primitive five-basals.
could be properly oriented’, and these showed the bc anchylosis
(Pl. II, No. 4), as did two specimens of M. obconicus ? Hall, and one
of the type specimens of M. roemeri. The other four-basal forms
of the Melocrinidae(?) and the Eucalyptocrinidae? have the
a—b—cd—e— type of base.
Fig. 5, No. 3, illustrates a type in which three adjacent basals
have been anchylosed (abc—d—e—). Here again five combinations
‘In orienting these specimens the anal tube was used as the reference point.
? This orientation of Eucalyptocrinus is strictly arbitrary, as no indices for proper
orientation have as yet been discovered.
BASAL PLATES IN CRINOIDEA CAMERATA 7 507
are possible: abc—d—e—, a—bcd—e—, a—b—cde—, b—c—dea—,
and c—d—eab—. Of these combinations one, the abc—d—e—
combination, is found in Zophocrinus, as figured. This orientation
does not agree with Bather’s interpretation of the genus,’ but is
based upon the discovery of the anus in a large number of speci-
mens studied by the writer in the Springer and Walker Museum
collections. ;
Fig. 5, No. 4, shows the anchylosis of four adjacent plates
(abcd—e—), leaving but one free plate. Here, however, any plate
of the five might have been the free plate, and five combinations
are possible: abcd—e—, a—bcde—, b—cdea—, c—deab—, and
d—eabc—. Of these combinations none have been discovered.
Fig. 5, No. 5, illustrates one of five possible combinations in
which only one suture exists (abcde—). Combinations 4 and 5
seem too asymmetrical from a structural viewpoint to occur as
either generic or specific characters, but might appear in cases of
delayed anchylosis, in which complete anchylosis is the normal
result.
Fig. 5, No. 6, illustrates the simple tripartite combination
(ab—c—de—), in which two pairs of basals are anchylosed. Of
the five possible combinations of this type four are now known:
a—bc—de—, in Allagecrinus americanus;? b—cd—ea—, in Stor-
thingocrinus’ and Hyocrinus (No.6,a)4; ab—c—de—, in S ybathocrinus
and the Platycrinidae (No. 6, 6); bc—d—ea—, in Hapalocrinus’ and
Stephanocrinus® (No. 6, c). The fifth combination (al—cd—e—)
has not yet been discovered.
Fig. 5, No. 7, illustrates one of the five possible combinations
in which three- and two-basals are anchylosed, as abc—de—, etc.
Of these only one is known, abc—de— in Mycocrinus,' as figured.
Fig. 5, No. 8, shows the complete type of anchylosis (abcde).
While this formula recognizes but one type of complete anchylosis,
= IRGi5 Oy 10/05 WSO), isi
2 This combination was found recently, by the writer, in two specimens of Allage-
crinus americanus in a large collection of that species made by Professor Weller at
Louisiana, Missouri.
3 Ref. 3, p. 426.
4 Ref. 6, p. 153. 6 Ref. 19, pp. 212, 351.
5 Ref. 21, pp. 95-105, Pls. 9, to. 7 Ref. 28, p. 110, Pl. 7, Fig. 4.
508 HERRICK E. WILSON
the type may have been derived by the simultaneous anchylosis
of the five primary plates, or from the closure of the remaining
sutures in any of the thirty possible combinations given above.
Dealing here with results alone, we see that thirty-one possible
modifications of the five primary basals are obtainable through
simple anchylosis.
[To be continued]
EXPLANATION OF PLATES
PLATE I
Teleiocrinus umbrosus Hall. Abnormal specimen cited by Wachsmuth and
Springer as confirmation of their theory
No. 1.—Oblique view of posterior interray, showing absence of anal plate
and one of the first interbrachials, and the reduction of the right-posterior basal.
Basal formula, ab—cd—e—; formula of posterior interray, o—1—3—4—2-.
No. 2.—View of right-posterior interray, showing normal arrangement of
interbrachials r—2—2—2-—, and reduction of right-posterior basal.
No. 4.—Posterior view.
No. 6.—Tegmen, showing position of anal tube.
Teleiocrinus umbrosus Hall. Springer collection; normal specimens
Fig. 3.—Posterior view, showing normal posterior interray and normal
base. Basal formula, a)—cd—ex—; formula of posterior interray, A —2—3—
4—1—. To be compared with Nos. 1 and 4.
No. 5.—Tegmen, showing position of anal tube in another specimen; to
be compared with No. 6.
PLATE II
Glyptocrinus decadactylus Hall. Springer collection, specimens having a
pentagonal base
No. 1.—Basal view, showing normal pentagonal base with five basals.
Basal formula, a—b—c—d—e-.
Chicagocrinus inornatus Weller (type). University of Chicago Paleontological
Collection, No. 10787
No. 2.—Basal view, showing anchylosis and reduction of antero-lateral
basals and compensating enlargement of postero-lateral basals. Basal formula,
a—b—cd—e—.
Melocrinus calvint Wachsmuth and Springer. Springer collection
No. 3.—Posterior view.
No. 4.—Basal view of same specimen, showing anchylosis and reduction
of sinstro-lateral basals and compensating enlargement of posterior and right-
anterior basals. Basal formula, a—bc—d—e—.
BASAL PLATES IN CRINOIDEA CAMERATA 509
Stephanocrinus angulatus Conrad. University of Chicago paleontological
Collection, No. 10787
No. 5.—Basal view, showing anchylosis and reduction of right-posterior
and posterior and sinstro-lateral basals, and compensating enlargement of
right-anterior basal. Basal formula, ea—bc—d—. Note reduction of right-
posterior and left-anterior radials.
Platycrinus subspinosus Hall. Springer collection
No. 6.—Basal view, showing normal Platycrinus type of anchylosis.
Basal formula, a—c—de—. To be compared with No. 5.
Abacocrinus tesselatus Angelin. Springer collection, specimens having a
hexagonal base
No. 7.—Basal view, showing asymmetry of posterior radials, enlarge-
ment and trunkation of posterior basal, and anchylosis and reduction of
antero-lateral basals, coupled with compensating enlargement of postero-
lateral basals. Basal formula, a—b—cd—e-—.
Melocrinus sampsoni M. and G. (type). University of Chicago paleontological
collection, No. 6958; probably Actinocrinus chouteauensis S.A.M.
No. 8.—Basal view showing reappearance of anterior basal suture. Basal
formula, ab—c—d—ex—.
_Batocrinus. University of Chicago paleontological collection No. 9082
No. 10.—Basal view of normal specimen. Basal formula, ab—cd—ex—.
No. 11.—Basal view of abnormal specimen, showing reappearance of
anterior basal suture. Basal formula, ab—c—d—ex—.
Actinocrinus multiradiatus. University of Chicago paleontological
collection No. 8959
No. 9.—Basal ‘view with basé removed, showing asymmetry and reduc-
tion of posterior radials. Compare with Nos. 7-14.
Steganocrinus pentagonus Hall. Springer collection
No. 12.—Basal view of normal specimen, showing asymmetry and reduc-
tion of posterior radials. Basal formula, ab—cd—ex—.
No. 13.—Basal view of abnormal specimen, showing loss of the antero-
lateral and posterior basal sutures and the reappearance of the anterior and
left-posterior sutures. Basal formula bc—dea—; factor x may or may not
be present.
No. 14.—Basal view of another abnormal specimen, showing loss of right-
anterior basal suture and reappearance of anterior suture. Basal formula,
WG On.
No. 15.—Basal view of abnormal specimen, University of Chicago pale-
ontological collection, No. 8979, showing loss of anal plate. Basal formula,
b—cd—ea—. See Plate III.
510 HERRICK E. WILSON
PLATE III
Steganocrinus pentagonus Hall
No. 1.—Posterior view of abnormal form of PI. II, No. 15.
No. 2.—Tegmen of same specimen, showing position of anal tube.
No. 3.—Posterior view of normal specimen in Springer collection. To be
compared with No. 1.
Hexacrinus elongatus Goldiuss. Springer collection
No. 4.—Basal view of normal form. Basal formula ab—cd—ex—.
Note reduction of posterior radials.
Hexacrinus anglypticus Goldfuss. Springer collection
No. 5.—Basal view of abnormal form, showing loss of posterior basal
suture and reappearance of left-posterior suture. Anchylosis of anterior
basals normal. Basal formula, b—cd—ea—; factor x may or may not be
present.
No. 6.—Basal view of another abnormal specimen, showing loss of right-
anterior basal suture and reappearance of anterior suture. Basal formula,
ab—c—dex—.
Talarocrinus patei M. & G, Springer collection
No.7.—Basal view of normal specimen. X2. Basal formula, abec—dex—.
No. 8.—Basal view of abnormal specimen, showing reappearance of left-
posterior basal suture. X2. Basal formula, a—bc—dex—.
No. 9.—Basal view of another abnormal specimen, showing reappearance
of left-anterior basal suture. X2. Basal formula, ab—c—dex—.
No. 1o.—Basal view of another abnormal specimen, showing loss of
posterior basal suture and reappearance of left-posterior and right-anterior
sutures. X2. Basal formula, bc—d—ea—. Factor «x may or may not be
present.
Pierotocrinus cirnarius Lyon, Springer collection; Tegmen figured by
Wachsmuth and Springer, ref. 39, Pl. LX XIX, Figs. 7a, 76
No. 11.—Basal view, showing great reduction of anal plate, and asym-
metry of posterior radials. Basal formula, abc—dex—.
Dichocrinus inornatus W. and Sp. Springer collection
No. 12.—Lateral view of normal specimen. Xr}.
No. 15.—Tegmen of normal specimen showing flexible condition of anal
tube and interambulacral areas. X 2.
Platycrinus symmetricus W. and Sp. Springer collection
No. 13.—Lateral view, showing similarity to No. 12. 1}
No. 14.—Tegmen of young specimen, figured by ref. 39, Pl. LXIX, Fig.
1c. Note flexible condition of anal tube and interambulacral areas, and
general similarity to No. 15. X2.
PLATE I
JournaL oF Grotocy, Vou. XXIV, No. 5
JourNaL or Georocy, Vor. XXIV, No. 5 PrAny 1t
Journat oF Grotocy, VoL. XXIV, No. 5 ~ Prats TI
VARIATIONS OF GLACIERS. XxX?
HARRY FIELDING REID
Johns Hopkins University, Baltimore, Maryland
The following is a summary of the Nineteenth Annual Report
of the International Committee on Glaciers.”
THE REPORT OF GLACIERS FOR I9g13
Swiss Alps.—Sixty-one glaciers were measured in 1913; a
larger proportion were retreating this year than in 1912. The
Rhone Glacier, however, has grown in thickness, throughout, with
an increase of velocity and an advance of the tongue.
Eastern Alps.—The summer of 1913, like its predecessor, was
very wet, especially on the north side of the Alps; the conditions
during both summers must have influenced the glaciers in 1913. Of
the 37 glaciers observed 8 were advancing, 4 were stationary, and
only 25 continued their retreat. The increase in the number of
advancing glaciers is certain, and the retreat of the glaciers of the
Eastern Alps has diminished; it is doubtful if the retreat can now
be said to be the prevailing condition.
Italian Alps.—In the Piedmont Alps the snowfall has been too
heavy to permit of good observations, but the glaciers are appar-
ently retreating. Careful photographic surveys have been made
of three of the large glaciers on the south side of the Mount Blanc
massif; these glaciers are retreating; but the snowfall in the higher
regions has increased, so much so in places as to, cause a marked
change in the appearance of the mountains. In the Monte Rosa
group the observed glaciers were retreating. In the Lombard
Alps some glaciers were making slight advances, some slight
retreats. On the whole, the large glaciers of the Italian Alps were
retreating, but a number of the smaller ones were slightly advancing
or were in a doubtful condition.
t Earlier reports appeared in the Journal of Geology, Vols. III-X XIII.
2 Zeitschrift fiir Gletscherkunde, [X (1914), 42-65.
Gara
HARRY FIELDING REID
on
m
bo
Swedish Alps —But one glacier, the Mikka, was observed, and
it showed no change.
Norwegian Alps.—All the 16 glaciers examined in the Folgefon
and the Jostedalsbrae were retreating with one exception. On
the other hand, in the Swartisen, the Okstinderne, and the
Frostisen, 7 glaciers were advancing, one retreating, and two were
stationary.
Russia.— Observations in the Caucasus and in Turkestan have
laid the basis for the determination of future changes. One glacier
in the Caucasus was retreating and two were stationary.
Canada.—No observations have been recorded in the last two
years;' but during the few years before r1o1o the Illecillewaet,
the Asulkan, the Victoria, and the Yoho glaciers were all re-
treating. Shortly before 1909, however, the Asulkan made an
advance.
Himalaya.—The greater part of the information collected refers
to variations which occurred some years ago. The positions of the
ends of many glaciers were determined in 1906, but later observa-
tions are not available. At that date there was evidence that the
glaciers were generally retreating.
New Zealand Alps——Here also observations are scanty. For
about ten years aiter the middle of the nineties, several of the larger
glaciers advanced. Later conditions have not been reported.
REPORT ON THE GLACIERS OF THE UNITED STATES FOR IQI4
Mr. F. E. Matthes sends me the following information:
The snowfall during the winter of 1913-14 in the Sierras was so heavy
that the glaciers were still completely covered at the end of September; the
snow extended even beyond some moraines which encircle the glaciers at a
short distance. These moraines are recent; the youngest is comparable to
the moraines which marked the advance of the Alpine glaciers at the end of the
eighteenth and the beginning of the nineteenth centuries. Historical evidence
is not available to determine the actual time when these moraines were formed;
but the presence of big trees (Sequoia Washigtoniana) near the glaciers may
supply the information; for their rings of growth contain a trustworthy record
of the climatic fluctuations of the last three thousand years.
«The last report on the Canadian glaciers in this series was in Variations of
Glaciers, XIII, report for 1906. See Journal of Geology, XVI (1908), p. 665.
VARIATIONS OF GLACIERS 513
Professor Lawrence Martin sends me the following information
regarding the Alaskan glaciers:
College Fiord.—Miss Keen visited Prince William Sound during the sum-
mer of 1914 for the exploration of the Harvard Glacier, and made careful
observations of the variations of a number of other glaciers.t | She found that
the Harvard Glacier is 18 miles long, or about 28 miles if the Brunonian
Glacier tributary is included. It rises at an elevation of about 7,500 feet.
The eastern side of the end of Harvard Glacier seems to have retreated slightly
between 1910 and 1914, but the western edge near Radcliffe Glacier was still
advancing. There was no observable change in Downer, Baltimore, and Smith
glaciers. Bryn Mawr may have retreated slightly; the barren zone at its
northern border was widest, but the evidence was conflicting, for a shrub north
of the glacier was being overturned at the time of Miss Keen’s visit. Vassar
Glacier was more crevassed Jn t914 than in 1910, but had not advanced appre-
ciably; Wellesley Glacier had retreated slightly; Yale Glacier seems to have
advanced a little; Barnard had a slight forward movement.
Harriman Fiord.—The-recession of Barry Glacier, observed in 1913, con-
tinued in 1914. The total recession of different parts of the ice front, from
1910 to September 25, 1914, was 3,000-7,000 feet. Cascade Glacier was
nearly independent of the Barry in 1914. Of the other ice tongues in Harriman
Fiord the Baker Glacier advanced at least 1,000 feet between 1910 and 1914,
and spread considerably at both borders. The Harriman and Roaring glaciers
seem to be still advancing. A small unnamed ice mass on the slopes of Mt.
Muir moved forward slightly. The Surprise, Cataract, Serpentine, Toboggan,
and Dirty glaciers were unchanged.
Eastern Prince William Sound.—The Valdez Glacier, continuing its long-
maintained recession, melted back about 200 feet from 1909 to August to,
1914. Shoup Glacier advanced very slightly. Columbia Glacier, the largest
ice tongue in Prince William Sound, is also the most interesting, for it has
continued the slow forward movement that has been in progress since before
1908. Miss Keen found that the eastern border advanced 1,500 feet between
1910 and September 30, 1914, and spread laterally; in other parts the advance
was less, being perhaps 1,300 feet on Heather Island. Photographs of Childs
Glacier, by Robert Sewall, show that in July, 1914, its northern border was
retreating.
Southeastern Alaska.—It was reported in the Juneau papers that Norris
Glacier, in Taku Inlet, had made a considerable advance. A photograph of
the Taku Glacier, taken about 1907, shows a distinct advance since 18go.
Dr. Martin has tabulated the snowfall and temperature as
recorded at several Alaskan stations. He finds not only great
differences in different years, but the years of maximum snowfall
t Bulletin of the American Geographical Society, XLVII (1915), 117-19.
514 HARRY FIELDING REID
at the various stations are different, so that it is not safe to draw
any detailed conclusions about the snowfall in the mountains from
the records at the stations; though the general trends are the same.
The annual snowfall at Killisnoo, somewhat more than one hundred
miles southeast of Muir Glacier, between 1891 and 1896 was about
twice as great as it has been since then; but the glaciers do not show
corresponding variations. Temperature records have been kept
at Sitka, with two short intermissions, since 1828. The average
temperature for the five months from May to September in the
years 1828-77 and in the years 1906-13 differs by only one-tenth
of a degree Fahrenheit. The average temperature at Juneau for
the same months during the years 1906-13 is about 2° F. higher than
during the years 1883-96. It does not seem possible to infer any
definite relations between temperature and glacier variations from
these records.
The United States Geological Survey has published a map of a
portion of the Chugach Mountains, northeast of Prince William
Sound, on a scale of about one inch to the mile (Port Valdez District,
Alaska; sheet 602 B). It shows a large area of glaciers and snow-
fields. Parts of the Columbia, Shoup, and Valdez glaciers appear
onit. Unfortunately the contours are not carried over the glaciers,
but the altitudes of a number of points are indicated so that marked
future changes in the thickness of the ice will be determinable.
Other new maps of Alaskan glaciers cover the Haganita~-Bremner
region, northeast of the Copper River Cafion,' the Bering Glacier,
and the western border of the Malaspina Glacier at Icy Bay,? and
part of the Kenai Peninsula.s An excellent topographic map, on
the one-inch scale, showing all the glaciers and their relations to the
mountains and rivers, accompanies M. C. Campbell’s Popular
Guide to the Glacier National Park.*| Pamphlets containing popular
accounts of the glaciers of Mount Rainier and of Glacier National
Park have been issued by the Department of the Interior.$
t Bull. U.S. Geol. Surv. No. 576, Plate I. 3 Tbid., Plate VIII.
2 Bull. U.S. Geol. Surv. No. 592, Plate IV. 4 Bull. U.S. Geol. Surv. No. 600.
5 Mount Rainier and Its Glaciers, by F. E. Matthes; Glaciers of Glacier National
Park, by W. C. Alden.
REVIEWS
Climates of Geologic Time. By CHARLES SCHUCHERT. Carnegie
Institution of Washington, Publ. No. 192, pp. 263-98, Figs.
87-90.
There has been a progressive advance, in late years a most rapid
one, from the conception of a former hot, dense, vaporous earth atmos-
phere, the natural corollary of the Laplacian hypothesis. Knowledge
of glacial climates, which had its beginning in studies in the Alps early
in the eighteenth century, has grown until not only has there been
demonstrated a world-wide lowering of temperature with glaciation of
much of the Northern Hemisphere in recent geologic time, but there
has been proved as well a number of such glacial periods in earlier
times. The cold climates which have periodically affected the earth
more or less widely since the beginning of geologic history have been of
short geologic duration. The data at hand indicate at least four well-
marked glaciations: (1) earliest Proterozoic, shown by the widespread
“slate conglomerates”’ at the base of the Lower ‘Huronian in Canada;
(2) latest Proterozoic, marked by thick, widespread tillites beneath the
Lower Cambrian of Southern Australia, and by the Gaisa formation of
Northern Norway, both now thought to be latest Proterozoic instead of
Lower Cambrian; (3) Permian, abundantly proven by tillites in many
parts of the world, mostly between latitudes 20° N. and 40°S.; and
(4) Pleistocene, the deposits of which mantle much of the Northern
Hemisphere. Less well-marked cold periods seem to have occurred (5) at
another part of the Proterozoic, for the glacial materials of this age in
South Africa represent neither the earlier nor the later part of the era;
(6) in the Lower Devonian of.South Africa, shown by the Table
Mountain series, and (7) in the early Eocene, indicated by deposits
in the San Juan Mountains of Colorado. The greatest reductions of
temperatures, so far as known, varied between the hemispheres.
Guided by the postulate that the living things of sea and land always
have been affected by climatic conditions much as now, climate varia-
tions are to be observed in the succession of plants and animals recorded
as fossils. In addition, the color and general character of the sedimen-
tary deposits afford light on climatic conditions at the time of their
515
516 REVIEWS
deposition. In spite of widespread glaciation at certain periods, the
Proterozoic era had, in the main, a rather warm, equable climate. This
is shown by the enormously thick limestone deposits (50,000 feet in
Canada), abundance of large Archaeocyathinae, widely distributed
graphites, and presence of coal. The Cambrian, with an abundance of
shallow-water life, had a uniformly warm temperature which continued
into the Ordovician and Silurian. The red shales, gypsum deposits,
salt beds, and scant, depauperate fauna of the late Silurian indicate
aridity and possible coolness, the latter expressed perhaps by local glacia-
tion (South Africa). The deposits of Northern Europe in the Devonian
probably marked a cool, somewhat arid climate, and the great change in
the life-forms in the Middle Devonian may be further evidence of the
same thing. The climate of the middle and later part of the Devonian
was warm; that of the Carboniferous, warm-temperate to subtropic.
The great variety of marine life, abundance of reef corals in high lati-
tudes, extensive coal deposits, subtropical flora, and large-sized insects,
all suggest this. The adverse climate of the Permian is clearly shown in
the glacial tillites, red shales, salt and gypsum deposits (to thickness of
3,300 feet), and depauperate, scanty fauna. The sweeping change in
the types of life seen in the Triassic is most convincing proof of climatic
severities at this time. Large trees (to 8 feet diameter), and their absence
of rings, luxuriant ferns, and thick deposits of limestones in high lati-
tudes, all suggest warmth. The late Triassic-Lias probably saw a
reduction of temperature, for of the Triassic ammonites (1,000 species)
none passed into the Jurassic, the insects were uniformly dwarfed, and
the corals, both numerically and geographically, were very much re-
stricted. The Jurassic was a period of remarkably warm, equable climate.
The wide distribution and variety of ammonites (15,000 species), their
presence with corals and marine saurians in very high latitudes, and the
very cosmopolitan, luxuriant floras are to be noted. The Comanchean-
Cretaceous marks the introduction of hardwood forests and may indi-
cate a cooler climate than the Jurassic; but the presence of magnolias
in Greenland and Alaska shows at least warm-temperate conditions
there. The Cretaceous is distinguished by a remarkable deployment of
the immense land reptiles and very thick limestone deposits. Climatic
conditions in the Tertiary are not sharply different from those of the
Cretaceous. Middle and late Eocene floras show many tropical marks,
Oligocene faunas are varied and large sized, especially the foraminifers
(nummulites), the Miocene shows a distribution of warm-temperature
plants in Spitzbergen and Grinnell Land, but the late Miocene was, at
REVIEWS 517
least in many places, cooler. The Pliocene was rather warm but un-
doubtedly became colder toward the beginning of the Pleistocene when
glacial conditions reached full expression.
The author concludes that the marked climatic variations of the
past are primarily due to periodic changes in the topography of the land
surface, modified by the variations in the amount of heat stored in the
oceans, and the change in the composition of the atmosphere which
conditions the storage of solar radiation. Supplementary notes with
quotations from original descriptions of pre-Permian tillites and a bibliog-
raphy of the subject are appended. ee
= Cae
Oceania. By P. Marswatyt. Handbuch der regionalen Geologie,
5. Heft, Band VII, Abteilung 2. Heidelberg, 1912. Pp. 36,
figs. 10.
Oceania, limited on the west by the Marianne, Pelew, and Caroline
islands, on the east by the Sandwich Islands, is a region measuring about
8,400 miles east and west, and 4,200 miles north and south. Most of
the islands are small, aggregated in rather well-defined groups or lines,
and within the limits of each group the geological and physical structures
are somewhat uniform. With the exception of the largest only, the
islands are volcanic or composed of coralline limestone, and almost
every island is fringed by coral reefs. The basin of the Pacific is of
great, and nearly uniform, depth (2,500-3,000 fathoms), but in the west
part of Oceania the ocean depths are far less regular. Very deep troughs
are found subparallel to some of the island chains and their connecting
submarine ridges, and the location of the shallows and basins is suggestive
of important structural relations. The island chains seem to define
at least four mountain ranges which are seen to converge toward North-
ern New Zealand, a region therefore of great structural importance. The
true border of the Pacific basin segment of the earth’s crust is marked
by a fairly definite line, indicated by the submarine elevations, areas of
raised coral rock, and the distribution of andesitic rocks. This line
passes through the Kermadec, Tonga, Fiji, New Hebrides, and Solomon
islands, and is noteworthy as the belt of present volcanic activity.
Triassic fossils in New Zealand and New Caledonia indicate their coastal
connection in the past, and the present faunal and floral distribution
is strongly suggestive of the former existence of a continental area
limited by the island line mentioned. Coral growths of the Pacific
518 REVIEWS
generally imply considerable subsidence, though in places this has been
superseded by elevation. A brief description of the physical character
and geology of each of the island groups, so far as known, comprises the
central part of the paper. A bibliography of the subject is appended.
RCo
Geology of the Gold Belt in the James River Basin, Virginia. By
STEPHEN TABER. Virginia Geol. Surv., Bull. No. VII, 1913.
Pp. 271, figs. 23, maps 2, pls. 8.
The gold mines are localized mainly in Goochland and Fluvanna
counties. Free gold occurs in quartz veins which cut pre-Cambrian
quartzites, schists, and gneisses. The gold seems to be associated with
granite intrusions, possibly of Cambrian age.
The author suggests that this district illustrates the formation of
quartz veins by the force of crystallization. The value of the gold
produced in this region amounts to about $6,000.00 per annum.
T Te
Pre-Cambrian Algonkian Algal Flora. By CHARLES D. WALCOTT.
Smithsonian Misc. Coll.; LXIV, No. 2, 1914. Pp. 153, pls. 19.
Fossil algal flora, produced by blue-green algae, are found in the
Algonkian formations of the Cordilleran region. Walcott describes
and figures 8 new genera and 12 new species of algae from the Belt series.
Before the discussion of the algal remains, there is a discussion of the
continental conditions and sedimentation of Algonkian times. From
Robson Peak, British Columbia, to Arizona and southern California, a>
distance of over a thousand miles, there is a marked Algonkian-Cambrian
unconformity. Preceding this advance of the Cambrian sea, the
Algonkian was a time of continental elevation and of largely terrigenous
sedimentation in non-marine bodies of water; also there was some sub-
aerial deposition. Marine sediments accumulated along the shores of
the continents, but they are now far buried, and everywhere lost to our
knowledge. This unknown marine life, preceding the Cambrian
invasion, belongs to what the author calls “Lipalian” time. Red
sandstones and shales in the west suggest an arid and, possibly, a cold
climate. The thick limestones in the western interior are explained as
having been deposited from non-marine waters by algae.
Ts Tate
RAGE OBLIGATIONS
—LuL1, R. S. Triassic Life of the Connecticut Valley. [Connecticut Geo-
logical and Natural History Survey, Bulletin 24. Hartford, 1915.]
—Martitanp, A. G. Annual Progress Report of the Geological Survey of
Western Australia, for the Year 1913. [Perth, 1914.|
Annual Progress Report of the Geological Survey of Western Aus-
tralia for r914. [Western Australia Geological Survey. Perth, 1915.]
MAKINEN, Erro. Die Granitpegmatite von Tammela in Finnland und ihre
Minerale. [Bulletin No. 35 de la Commission Géologique de Finlande.
Helsingfors, January, 1913.|
—MarsHatt, R. B. Profile Surveys in Bear River Basin, Idaho. [U.S.
Geological Survey, Water-Supply Paper 350. Washington, 1914.|
Profile Surveys in Willamette River Basin, Oregon. [U.S. Geo-
logical Survey, Water-Supply Paper 349. (Prepared in co-operation
with the State of Oregon.) Washington, 1914.]
Results of Spirit Leveling in Idaho, 1896 to 1914, inclusive. [U-S.
_ Geological Survey, Bulletin 567. Washington, 1915.]
Results of Spirit Leveling in Minnesota, 1897 to 1914, inclusive.
[U.S. Geological Survey, Bulletin 560. (Work done in co-operation with
the Sate of Minnesota from 1909 to 1914, inclusive; Geo. A. Ralph, Chief
Engineer of State Drainage Commission.) Washington, 1915.|
—McLetsu, Joun. Annual Report on the Mineral Production of Canada
during the Calendar Year 1913. [Canada Department of Mines, Mines
Branch No. 320. Ottawa, 1914.]
—Metnzer, O. E., anp Hare, R. F. Geology and Water Resources of
Tularosa Basin, New Mexico. [U.S. Geological Survey, Water-Supply
Paper 343. (Prepared in co-operation with the New Mexico Agricultural
Experiment Station.) Washington, 1915.]
—Merrii1, G. P. On the Monticellite-like Mineral in Meteorites, and on
Oldhamite as a Meteoric Constituent. [Proceedings of the National
Academy of Sciences, Vol. I, p. 302. Washington, 1915.]
The Fisher, Polk County, Minnesota, Meteorite. [No. 2084. From
the Proceedings of the U.S. National Museum, Vol. XLVIII, pp. 503-6.
Washington: Government Printing Office, May 3, 1915.]
—Michigan College of Mines, Year Book of the, 1914-1915. Announcement
of Courses for 1915-1916. [Houghton, 1915.]
—Mwpteton, J. The Production of Sand-Lime Brick in 1914. [From
Mineral Resources of the United States, 1914, Part IJ. Washington,
1915.|
51¢
520 RECENT PUBLICATIONS
—MINERALCHEMIE, Handbuch der. Bd. II 8 (Bog. 21-30). [Dresden und
Leipzig: Verlag von Theodor Steinkopff, 1915.]
—Mines and Metallurgy, School of, University of Missouri. Catalogue, 1914-
to1s. Bulletin, March, 1915. Vol. VII, No. 2. [Rolla, ro15.]
Bulletin, June, 1915. Vol. VII. No. 3. ([Rolla, r915.]
—Mining Congress Journal, The. Vol. I, Nos. 1 and 2. [Washington,
February, 1915.]
—Mississippi Geological Survey Commission, Third Biennial Report of,
June 30, 1909—June 30, r911. [Jackson, ro1t.]
—Missouri Bureau of Geology and Mines. Base Map of Missouri. Com-
piled in co-operation with the U.S. Geological Survey. [Rolla, 1914.]
—Perkins, G. H. Report of the State Geologist on the Mineral Industries
and Geology of Vermont, 1913-1914. [Burlington, 1914.]
—PocuE, J. E. The Turquoise, A Study of Its History, Mineralogy, Geology,
Ethnology, Archaeology, Mythology, Folklore, and Technology. [Mem-
oirs of the National Academy of Sciences. Vol. XII. Third Memoir.
Washington, 1915.] :
—REINECKE, L. Physiography of the Beaverdell Map-Area and the Southern
Part of the Interior Plateaus of British Columbia. [Canada Department
of Mines, Museum Bulletin No. 11, Geological Survey, Geological Series
No. 23. Ottawa, ror5.]
—Resources of Tennessee, The. Vol. V. [Nashville: Tennessee Geological
Survey, I915.]
—Rice, G. S. What a Miner Can Do to Prevent Explosions of Gas and
Coal Dust. [U.S. Bureau of Mines, Miners’ Circular 21. Washington,
IQI5.|
—Royal Geographical Society, Year-Book and Record, tg914. [London:
Kensington Gore, S.W., 1914.]
—ScHRADER, F. C. Mineral Deposits of the Santa Rita and Patagonia
Mountains, Arizona. With Contributions by James H. Hitz. [U-S.
Geological Survey, Bulletin 582. Washington, rors.]
—SEDERHOLM, J. J. Weitere Mitteilungen iiber Bruchspalten mit beson-
derer Beziehung zur Geomorphologie von Fennoskandia. [Bulletin
No. 37 de la Commission Géologique de Finlande. Helsingfors, June,
1913.]
—Seismological Society of America, Bulletin of the. Vol. V, No. 1. [Stan-
ford University, California, rot5.]
| Animal Communities
in Temperate America
A STUDY IN ANIMAL ECOLOGY
Designed to serve as a reference work and
textbook in the New Science of Animal Ecology
By VICTOR ERNEST SHELFORD
Assistant Professor of Zodlogy in the
University of Illinois
Illustrated with 300 figures, maps, and diagrams
HIS volume by Professor Shelford pre-
; T sents the principles of field ecology,
_ illustrated by the more widely distrib-
uted animal habitats of the eastern half of
temperate North America, and the aquatic
habitats of a much larger territory. The
material has been accumulated during ten _
years of field study, from the point of view of
_ modern ecology, in various parts of the United
States, though most of the material is drawn
from the Chicago Region. The book is de-
signed to serve as a reference work and a
pexthook ct in es new Science of field ecology.
— - 380 pages, 8v0, cloth; price $3.00, postage exira
“(weight 2 lbs. 12 02: y
The rately, of EE Press
Chicago - Seas - Illinois
Do You Want to Know
What Your Handwriting
~ Reveals?
WE have published a fascinating
booklet of 32 pages on the sub-
ject of graphology, by William Leslie
French. Every reader of this publi-
cation will be interested in comparing
the examples of handwriting in judg-
ing character and disposition of the
writer.
A copy of this booklet and 12 differ- _
ent patterns of The Spencerian
Steel Pens will be sent postpaid on
receipt of ten cents.
If you can do good work with a poor pen
_ you can do better work with a good pen.
Silver plated Falcon pens, smooth points,
wear long, will not corrode.
SPENCERIAN PEN CO.
349 Broadway - - - New York City
TEACHERS
ne dae ee OF
BIOLOGY AND GEOLOGY
Will find the Bulletins of the Geo-
graphic Society of Chicago of special
value for field trips, lectures, etc.
Write for descriptive circulars. .
The University of Chicago Press
Chicago Illinois
WE WANT TO BUY
Journal of Geology, Vols. I to
XXI. Quote shorter runs also,
and other geological periodicals.
INTERNATIONAL MAGAZINE CO.
Elizabeth, N. J.
THE ASTROPHYSICAL JOURNAL
Issued monthly except February and August. $5.00a year;
single copies, 65 cents. Foreign postage, 62 cents.
Whe Unibersity of Chicago }oress
CHICAGO, ILLINOIS
966
Duss Zip 1
{FRE DUPLICATE COPIESARENECDED
Daus Improved Tip Top Duplicator
is an ideal assistant, always ready to reproduce clean, clear,
perfect copies of letters, manuscripts, price lists, bills, i in-
voices, reports, drawings, menus, ete., etc. Don’t take
our word, try it yourself for
Ten days” trial without deposit
If not satisfactory, return and no questions asked. Makes
150 handwritten and 50 typewritten copies in a few min-
utes. Negatives require no washing out after using, and
negative rolls can be used from 15 to 20 times. Complete
outfit contains a continuous roll of Daus Non-Peeling Anti-
Stick Negative Roll. Capsize,8$x13inches. Price $7.50
_ FELIX K. DAUS DUPLICATOR CO.
Daus Building, 111 John Street, NEW YORK
and ee
FINE INKS 482 ADHESIVES
For those who KNOW
A New Proposition
A TYPEWRITER BY PARCEL POST
ON TEN DAYS’ FREE EXAMINATION
It is the
Remington
Junior
the very latest addition to the great
Remington family of typewriters. A new
and smaller Remington—built for the
needs of the professional man and the home
Me SD
Drawing Inks
Eternal Writing Ink
Engrossing Ink
s ° 9 Taurine Mucilage
Hi GQims? | Photo Mounter baste
Drawing Board Paste
Liquid Paste
Office Paste —
Vegetable Glue, Etc.
Are the Finest and Best Inks and Adhesives
Emancipate yourself from the use of corrosive and
ill-smelling inks and adhesives and adopt the
Higgins Inks and Adhesives. They will bea
revelation to you, they are so sweet, clean, well
put up, and withal so efficient.
At Dealers Generally
Mail this coupon today
Remington Typewriter Company
(Incorporated)
327 Broadway, New York
Send me a Remington Junior Typewriter,
price $50, on free examination. It is understood
that I may return the machine, if I choose,
within ten days. If I decide to purchase it, I
agree to pay for it in ro monthly payments of
$5 each.
CHAS. M. HIGGINS & CO., Mfrs.
Branches: Chicago, London
271 Ninth Street Brooklyn, N.Y.
The whole: school will
welcome the Balopticon
The school authorities, the parents, the
teachers, and the pupils will all proht by
the ee. of this notably superior lantern—the
Bausch [omb
BALOPTICON
THE PERFECT STEREOPTICON
The images projected by the Balopticon are wonderfully clear and vivid over the entire field;
the lantern itself is simple to operate, and built for lang and steady use. Its newly developed,
gas-filled Mazda lamp gives more brilliant illumination than the alternating-current arc, with
much less current expense, and is noiseless and automatic.
Models for lantern slides and opaque objects (maps, photos, pictures, specimens, etc.). Also combined models
for both forms, with instant interchange.
Model C (illustrated) for slides, price from $30.00 up. Other models from $20.00 up.
Write for illustrated price list and booklets containing suggestions for the use of the Balopticon
Bausch £3 jomb Optical G.
554 ST. PAUL STREET ROCHESTER, N.Y.
NEW YORK WASHINGTON CHICAGO SAN FRANCISCO
Leading American Makers of Photographic Lenses, Microscopes, Projection Lanterns (Balopticons), Stereo
Prism Binoculars and other High-Grade Optical Products
arenas hein Ee ao ee )
JOURNAL or GEOLOGY
A -SEMI-QUARTERLY
ae a gai EDITED BY
o «
‘ RGN THOMAS C, CHAMBERLIN AND ROLLIN D. SALISBURY
With the Active Collaboration of
SAMUEL W. WILLISTON, Vertebrate Paleontology ALBERT JOHANNSEN, Petrology
2 : STUART WELLER, Invertebrate Paleontology ROLLIN T. CHAMBERLIN, Dynamic Geology
_ ALBERT D. BROKAW, Economic Geology
ASSOCIATE EDITORS
SIR. ARCHIBALD GEIKIE, Great Britain JOSEPH P.IDDINGS, Washington, D.C. -
CHARLES BARROIS, France JOHN C. BRANNER, Leland Stanford Junior University
ALBRECHT PENCK, Germany RICHARD A. F. PENROSE, Jr., Philadelphia, Pa.
HANS REUSCH, Norway : WILLIAM B. CLARK, Johns Hopkins University
GERARD “DEGEER, Sweden ; 4 WILLIAM H. HOBBS, University of Michigan
T. W. EDGEWORTH DAVID, Australia FRANK D. ADAMS, McGill University
BAILEY WILLIS, Leland Stanford Junior University CHARLES K, LEITH, University of Wisconsin
‘GROVE K. GILBERT, Washington, D.C. WALLACE W. ATWOOD, Harvard University
CHARLES D. WALCOTT, Smithsonian Institution WILLIAM H, EMMONS, University of Minnesota
HENRY’ ‘Ss. WILLIAMS, Cornell University ARTHUR L. DAY, Carnegie Institution
SEPTEMBER-OCTOBER 1916
THE PRE-WISCONSIN DRIFT OF NORTH DAKOTA shies. Wise ix Ce cel ONIN etc 2
EVOLUTION OF THE BASAL PLATES IN Bie A ates CRINOIDEA CAMERATA, II
é HErrRIcK-E. WILSON = 533
BIRRERENTIATION IN INTERCRUSTAL MAGMA BASINS - - ALFRED HaRKER 554
STRATIGRAPHY OF THE SKYKOMISH BASIN, WASHINGTON "Warren S.. SMITH. 550
“PUFF” CONES ON MOUNT USU ele ee Mella ees, se! adam uate a a aS OINOURIE Seg
ORIGIN OF FOLIATION IN THE PRE-CAMBRIAN ROCKS OF NORTHERN NEW
SAGAS - - - - - - - - - - - WILLIAM J. MILLER 587
THE COMPOSITION OF THE AVERAGE IGNEOUS ROCK -~ - ApotpH KNopr 620
BORER Reese a Goria = ee cSt tes nO
THE UNIVERSITY OF CHICAGO PRESS
CHICAGO, ILLINOIS, U.S.A.
AGENTS
THE CAMBRIDGE UNIVERSITY PRESS, Lonpon AND EDINBURGH
: KARL W. HIERSEMANN, LErpzic
haan THE MARUZEN-KABUSHIKI-KAISHA, Toxyo, Osaka, Kyoto, Fukuoka, SENDAI
tims THE MISSION BOOK COMPANY, SHANGHAI
THE JOURNAL OF GEOLOGY
EDITED BY veal
THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
With the Active Collaboration of
SAMUEL W. WILLISTON ALBERT JOHANNSEN
Vertebrate Paleontology Petrology
STUART WELLER ROLLIN T. CHAMBERLIN
Invertebrate Paleontology Dynamic Geology
ALBERT D. BROKAW
Economic Geology
e_——=— —— as
The Journal of Geology is published by the University of Chicago at the University Press semi- |
quarterly, on or about the following dates: February 1, March 15, May I, June 15, August 1, September 15, ©
November 1, December 15. §[ The subscription price is $4.00 per year; the price of single copies is
65 cents. Orders for service of less than a half-year will be charged at the single-copy rate. ‘] Postage is
prepaid by the publishers on all orders from the United States, Mexico, Cuba, Porto Rico, Panama Cana] —
Zone, Republic of Panama, Hawaiian Islands, Philippine Islands, Guam, Samoan Islands, Shanghai,
{] Postage is charged extra as follows: For Canada, 30 cents on annual subscriptions (total $4.30), on
single copies, 4 cents (total 69 cents); for all other countries in the Postal Union, 53 cents on annual
subscriptions (total $4.53), on single copies, II cents (total 76 cents). [Patrons are requested to make
all remittances payable to the University of Chicago Press in postal or express money orders or bank
drafts. F
The following agents have been appointed and are authorized to quote the prices indicated: _
For the British Empire: The Cambridge University Press, Fetter Lane, London, E.C. Yearly
subscriptions, including postage, 18s. 8¢. each; single copies, including postage, 3s. 2¢. each. _
For the continent of Europe: Karl W. Hiersemann, Kénigstrasse 29, Leipzig, Germany. Yearly
subscriptions, including postage, M. 22.65 each; single copies, including postage, M. 3.80 each.
For Japan and Korea: The Maruzen-Kabushiki-Kaisha, 11 to 16 Nihonbashi Tori Sanchome,
Tokyo, Japan. Yearly subscriptions, including postage, Yen 9.00 each; single copies, including
postage, Yen 1,50 each. { : .
For the Chinese Empire: The Mission Book Company, 18 Peking Road, Shanghai, China.
Yearly subscriptions, $4.00; single copies, 65 cents, or their equivalents in Chinese money. Postage
extra, if mailed direct outside of Shanghai, on yearly subscriptions 53 cents, on single copies II cents.
Claims for missing numbers should be made within the month following the regular month of
publication. The publishers expect to supply missing numbers free only when they have been lost in
transit.
Business correspondence should be addressed to The University of Chicago Press, Chicago, Ill.
Communications for the editors and manuscripts should be addressed to the Editors of /THE
JOURNAL OF GEOLOGY, the University of Chicago, Chicago, Ill.
Contributors are requested to write scientific and proper names with particular care and in citations
to follow the form shown in the pages of the Journal. . :
Separates, if desired, must be ordered in advance of publication. Separates of leading articles will be
printed as ordered, of which 50 (without covers) will be furnished grafts, the actual cost of the remainder —
(and covers, if desired) to be paid for by the author. The actual cost may vary, and will depend upon
the amount of work in re-making the pages into forms, presswork, paper, binding, etc. Separates
containing half-tones may be expected to cost somewhat more, the increase depending upon the number
of cuts and the amount of work required upon them.
Entered as second-class matter, March 20, 1893. at the Post-office at Chicago, Ill., under Ya Act of March 3, 1879.
VOLUME XXIV NUMBER 6
THE
WOURNAE OF GEOLOGY
SALT EMBERAOCROBETR: 1070
THE PRE-WISCONSIN DRIFT OF NORTH DAKOTA
_ A. G. LEONARD
North Dakota Geological Survey
Considerably over one-half of North Dakota is covered by
Wisconsin drift, which is found east of the Missouri plateau and
also occupies a belt of country along the eastern margin of the
plateau. The western border of the Wisconsin drift is marked by
the wide, massive Altamont Moraine which crosses the state
diagonally from northwest to southeast and has a width in places
of 20 miles. West of this moraine there is an older drift sheet
which extends from 70 to 130 miles beyond the Wisconsin drift
and in North Dakota covers an area at the surface of approxi-
mately 19,000 square miles. The border of this older drift crosses
the Montana boundary about 30 miles north of the Northern
Pacific Railroad. This older drift undoubtedly underlies the Wis-
consin drift of eastern North Dakota, but with possibly one excep-
tion it has not been observed in outcrops or recognized in wells.
East of the Missouri River the pre-Wisconsin drift, while covered
in many places by outwash silt from the Altamont Moraine, is
present in Emmons, Burleigh, eastern McLean and Mountrail,
and perhaps in Williams and Divide counties. West of the Mis-
sour! River the older drift covers most of Morton, Dunn, and
McKenzie counties, a corner of Stark, and all of Mercer and Oliver
Vol. XXIV, No. 6 521
A. G. LEONARD
U1
to
to
counties. In this area west of the river outcrops are not uncommon,
and thus the region is the most favorable in the state for the study
of the older drift sheet.
The following account of some of the features of the pre-
Wisconsin drift is based on observations made during the course
of tield work for the North Dakota Geological Survey, a portion of
the time in co-operation with the United States Geological Survey,
in Morton, Dunn, McKenzie, Burleigh, and other counties during
the years 1909 to rgt4 inclusive.
The older drift west of the Missouri is in most places thin and
has undergone great erosion. The deposit perhaps never had
any considerable thickness in this region except locally, where it
forms moraines, and much of the glacial material which was
formerly present has been swept away by streams. The drift
throughout much of the area is thus represented by bowlders and
gravel, the coarser materials left behind when the finer débris,
such as clay and sand, was carried off. There are extensive tracts
where little or no glacial material is present and where only an
occasional bowlder or a patch of gravel indicates that the ice sheet
once covered this region. The western margin of the older drift
is therefore poorly defined, and the mapping of it is based largely
on the distribution of glacial bowlders and gravel.
As would be expected from the foregoing characters, the pre-
Wisconsin drift has not, except in certain restricted areas, affected
the topography to any large extent. The region is one of many
streams and mature drainage, in striking contrast with the area
of the Wisconsin drift, with its few streams, numerous lakes, and
youthful topography.
PRE-WISCONSIN DRIFT OF BURLEIGH COUNTY
East of the Missouri River in Burleigh County, between the
river and the Altamont Moraine, the older drift is present, but the
occasional outcrops appear to indicate that it forms only a thin
veneer over the underlying rocks, seldom exceeding 8 or 1o feet in
thickness. It outcrops in the bluffs of the Missouri River 3 miles
northwest of Bismarck, where ro feet of till is found, and in the cut
at the east end of the Northern Pacific bridge it attains a thickness
THE PRE-WISCONSIN DRIFT OF NORTH DAKOTA 523
of 15 to 20 feet. The bowlder clay appears in a number of the cuts
along the Minneapolis, St. Paul & Sault Ste. Marie Railroad north
of Bismarck, here generally associated with water-laid drift. It
also outcrops at several points on Apple Creek, where it shows a
thickness of 10-12 feet.
DRIFT IN MORTON COUNTY
West of the Missouri River in Morton County the glacial drift
is represented almost wholly by gravel and bowlders, the latter
occurring in great numbers. These bowlders, which are mostly
granite, thickly cover the surface in many localities, resting
directly on the bedrock, and except in rare instances no drift
clay is associated with them. In some places they are scattered
loosely over the ground, but in many others they form a bed or
pavement in which the individual bowlders are in contact with
each other. These bowlder deposits or bowlder beds are especially
noticeable on the tops of divides and on upland areas. The bowl-
ders vary in size from 6 or 8 inches to several feet in diameter,
large ones measuring 8 and to feet being seen occasionally.
MORAINES OF LITTLE HEART RIVER BASIN
The most interesting and notable occurrence of glacial till
in Morton County is found in the basin of the Little Heart River
where the drift has
been heaped up into
morainic hills. During
the Glacial Period this
basin was _ probably
occupied by an ice
lobe of the continental
glacier, and this lobe
formed the belt of Fic. 1.—Bowlder-covered moraine hill of the
pre-Wisconsin drift, Little Heart Basin, northeastern
Morton County.
morainic hills which
nearly encircles the
broad valley plain and deposited more or less drift in the pre-
glacial valleys of the Little Heart and its tributaries. As the ice
524 A. G. LEONARD
melted, the waters flowing from it deposited much outwash silt in
the form of valley trains sloping away from the moraines. A
number of the morainic hills have been partially buried by the
outwash silt and rise
like islands from the ;
level plain of the valley ;
train. The morainic i
belt of bowlder-covered ;
hills and ridges is found j
near the base of the
slopes on either side of
the two valleys tribu- 4
tary to that of the Little 3
Heart River (Fig. 1).
Moraines cross the
Fic. 2.—Pre-Wisconsin till overlying Fort
Union beds on Tobacco Garden Creek several miles :
above its mouth, McKenzie County. valley in three places
and one belt of ridges
and hills continues unbroken along the south side of the valley of
the South Branch for a distance of 12 miles. The cultivated fields
extend up to the moraine
and end there where the
soil becomes too rocky
and the slopes too steep
for cultivation.
DRIFT IN MC KENZIE
COUNTY
Near the western
boundary of North
Dakota the pre-
Wisconsin ice sheet
reached 35-40 miles Fic. 3.—Pre-Wisconsin till resting on stratified
sand and gravel on Tobacco Garden Creek, near its
south of the Missouri
River and thus covered
the greater part of McKenzie County which lies between the
Yellowstone, Missouri, and Little Missouri rivers. The older
drift left by this ice sheet is well shown in many places in this
mouth.
THE PRE-WISCONSIN DRIFT OF NORTH DAKOTA 525
region and the glacier also caused important drainage changes.
The best exposures are
found on Sand Creek,
a short tributary of the
Missouri River several
miles east of Tobacco
Ganden Creek, on
Tobacco Garden Creek,
and on Clear Creek, a
tributary of the latter.
Near the mouth of
Tobacco Garden Creek
appears 58 feet of till
ineraecut, banks Tt) 1s Fic. 4.—Pre-Wisconsin drift resting on Fort
yellowish gray or drab Union sandstone, valley of Clear Creek, a tributary
of Tobacco Garden Creek, northeastern McKenzie
County.
in color, contains many
small bowlders, and
rests on Fort Union beds (Fig. 2). Not far from here is seen 18 feet
of bowlder clay over-
lying 15 feet of well-
stratified sand and
gravel (Fig. 3).
The valley of Clear
Creek was partly filled
with drift and there are
many good outcrops of
bowlder clay in the fre-
quent cut banks along
the stream where from
30 to 40 feet and over of
till is exposed (Fig. 4).
The greatest thickness
Fic. 5.—Pre-Wisconsin drift exposed on the foynd along this creek
tributary of Sand Creek, northeastern McKenzie
County.
was in Sec. 36, T.152N..,
R. 97 W., where in a
high bluff too feet of dark gray till overlies 100 feet of soft Fort
Union sandstone. This outcrop lies within the morainic area to
526 A. G. LEONARD
be described later, which probably accounts for the exceptional
thickness of the pre-Wisconsin drift at this point.
Another excellent drift section occurs in this same morainic
area 3 miles west and one-half mile south of Charlson, or 5 miles
south of the Missouri River on a tributary of Sand Creek (Fig. 5).
Here the following section appears in the steep bluff which rises
abruptly from creek-level:
Bt: In.
Sandy claysand ‘Soultewe ereemeee eet con cra i wk coe i eee 2
Sand and. clay incaltermating bands®< ©... W046. 4.5. :@ 3 sn ose ee 8
Gravel... 3/055 oo eee ert te eters rere | f al nae 8
Sand and. clay invaltermatmyp layers oS. sce ac ee 3
Gravel CORPSES. le) ee aes cater es Rte ect ees er ios mes RTE 8
Sando!" 295 RUA ere Rar BC pee ce pet tS gL ee 2 4
Gravel Saeco 3 gp ee ee Ree ite ok eee 7 8
Till or bowlder clay, dark gray in color, and containing large numbers
of pebbles and bowlders imbedded in the tough, hard clay. A
large proportion of the bowlders and pebbles are composed of
compact limestone and the till contains considerable blue shale
(Pierre ?). Thickness of till exposed above the creek......... 61
SS ae
The sand and gravel forming the stratified drift of the foregoing
section are light yellow in color. The drift hills just back of the
bluff rise 50-60 feet above the top of section, so that the total
thickness of the drift above creek-level is from 140 to 150 feet.
BOWLDER BED ON THE MISSOURI RIVER
An interesting bowlder deposit belonging to the pre-Wisconsin
drift is found along the Missouri River just above water-level,
2 miles below the Nesson Ferry and one-half mile below the mouth
of Tobacco Garden Creek (Fig. 6). This bed of bowlders shows a
thickness, above the normal stage of the river, of 12-14 feet and
its depth below water-level was not determined. The deposit
is well exposed along the water’s edge for a distance of nearly 100
yards, and scattered bowlders and ferruginous gravel occur at
intervals for another 200 yards. Overlying the bowlders is 15
feet of gravel, which is overlain in turn by silt and fine sand extend-
ing to the top of the terrace, 100 feet above the river. The bowlder
THE PRE-WISCONSIN DRIFT OF NORTH DAKOTA 527
bed is composed of bowlders of all sizes, those from 2 to 3 feet in
diameter being quite common, though those less than 1 foot in
diameter are most abundant. One sandstone bowlder measured
14 feet in length, another was g feet long, and another 4 feet.
Granite, limestone, petrified wood, and sandstone bowlders are
found, together with other kinds of rock. The interstices between
the coarser materials are filled with gravel and sand, and the whole
deposit is cemented into a rather firm, indurated mass. It is
very ferruginous and brown from the limonite forming the cement-
ing material, and in many places the bowlders are firmly held by
the iron cement and sand, which serve as a matrix in which the
bowlders are imbedded;
when the latter weather
out their shape is pre-
served in the matrix.
While some of the
bowlders of this de-
posit may have been
brought here by float-
ing ice, it is probable
that most of the deposit
was left here by the
pre-Wisconsin ice sheet
when it advanced south near mouth of Tobacco Garden Creek, McKenzie
of the river. The finer County.
materials of the drift,
if they were ever present, have been carried away, leaving the
gravel and bowlders, which were subsequently cemented by the
iron of the surface waters.
Fic. 6.—Bowlder bed on the Missouri River
MORAINE OF THE PRE-WISCONSIN DRIFT
Mention has been made on a previous page of the moraines
of the Little Heart River Basin, and in McKenzie County a much
more extensive moraine of the pre-Wisconsin drift forms a promi-
nent topographic feature of the region. It lies in the northeastern
part of the county, east of Tobacco Garden Creek, where it extends
on the upland from the edge of the Missouri Valley bluffs north
528 A. G. LEONARD
of Charlson in a southwesterly direction to the valley of Timber
Prong Creek in Secs. 14 and 15, T. 151 N., R. 97 W. It has a
length of 16 miles, an average width of 2 miles, and its area is about
30 square miles. This moraine shows well from Charlson, where
its ridges and hills are seen rising from too to 150 feet above the
flat plain in the foreground (Fig. 7). Within the morainic area
the surface is rough and hilly and the ground is thickly strewn with
bowlders. The topography is typically morainic, with numerous
irregular hills and ridges, while scattered among the hills are great
numbers of hollows or kettle-holes, some containing water and
others dry. Many of
the hills rise 50-125 feet
above the bottom of
the kettle-holes.
Where this moraine
crosses the valley of
Timber Prong Creek it
forms a dam, which
holds back the waters
of the upper valley and
forms a lake known
locally as Dimick Lake.
This moraine lake is
very irregular in shape and has an area of between two and three
square miles.
Fic. 7—Small lake in the moraine of the
pre-Wisconsin drift near Charlson, northeastern
McKenzie County.
North of the Missouri River another morainic belt occurs
which may be part of the pre-Wisconsin moraine just described
as extending southwest from the vicinity of Charlson, though it
is perhaps more likely to have been formed by the Earlier Wiscon-
sin ice sheet referred to on another page. It lies from 2-3 miles
west of White Earth Creek and with a width of 1-2 miles extends
north and south a distance of at least 6 or 8 miles between the
Missouri River and the Great Northern Railroad. Fifteen or 20
miles or more west of the Altamont Moraine the railroad crosses
a well-developed moraine extending 4 or 5 miles and perhaps more
north and south of Temple, and has a width of several miles. This
hilly belt lies about 9 miles west of the above-mentioned moraine
near White Earth Creek.
THE PRE-WISCONSIN DRIFT OF NORTH DAKOTA 529
CHARACTERISTICS OF THE PRE-WISCONSIN DRIFT
The topography of the older drift and the large amount of ero-
sion it has suffered compared with the Wisconsin till have been
mentioned on a previous page, where it was shown that in many
places only the coarser materials of the drift—the pebbles and bowl-
ders—remain as evidence that the ice sheet once covered the region.
But the color of the pre-Wisconsin till is generally unlike that of
the Wisconsin drift. The latter is commonly light yellow to light
gray in color as exposed in railroad cuts or along stream valleys,
but where the deeper till appears in fresh excavations it is seen to
have the blue color of
the unoxidized clay.
The pre-Wisconsin till,
on the other hand,
where best exposed
on Sand and Clear
creeks in northeastern
McKenzie County
(Fig. 8), is dark gray
in color throughout the
maximum observed Fic. 8.—The valley of Clear Creek where it
cuts through the moraine of the pre-Wisconsin
drift, northeastern McKenzie County.
= Eee _ Sannin
thickness of over 100
feet.
Except in the morainic areas the thickness of the pre-Wisconsin
drift is not great. West of the Missouri River it is seldom as much
as 8 or 10 feet and generally the thickness is not over 2 or 3 feet or
less. The thinness of the older drift is due partly to erosion which
has removed much of the glacial material and over a large part
of the area left only bowlders or a thin veneer of gravel, but partly
perhaps also to the fact that the drift may never have been very
thick in this region.
BOUNDARY OF THE PRE-WISCONSIN DRIFT
Chamberlin and Salisbury many years ago noted the presence
of an older drift beyond the Altamont Moraine and its approximate
boundary was shown on their map.t. The more detailed work of
«Terminal Moraine of the Second Glacial Epoch,” Third Ann. Report U.S.
Geol. Surv., pp. 291-402; also Plate XXXV.
530 A. G. LEONARD
recent years has shifted the margin somewhat farther west and
south and it is now provisionally located as shown on the accom-
panying map (Fig. 9).
Glacial drift is found 50 miles south of the mouth of the Yellow-
stone River, or within less than 15 miles of Glendive, Montana.
For a distance of 50 miles east of the western boundary of North
Dakota the drift margin extends approximately east and west and
lies 30-40 miles south of the Missouri River. North of the Kill-
deer Mountains the boundary swings sharply to the south, and
crossing the Knife River near the western edge of Dunn County
it takes a general southeasterly course across the state. The margin
of the drift is believed to cross the Northern Pacific Railroad and
the Heart River between 2 and 3 miles west of Gladstone. That
a lobe of the ice sheet crossed the Heart River at Gladstone is shown
by the presence of thick deposits of drift gravels on the upland
1-2 miles south of the Heart and at an elevation of between too
and 200 feet above river-level. In places the gravel and sand have
a thickness of at least 90 feet, and the deposit contains a number
of good-sized granite bowlders. A well-defined gravel ridge
marks the edge of the drift for 3 or 4 miles in this area south of the
Heart River at Gladstone. This ridge rises 30-40 feet above the
surface on either side and falls away rather abruptly on the south,
while on the north the slope is more gradual.
There is no evidence that the ice sheet extended more than
2 or 3 miles south of the railroad between Gladstone and Richard-
ton, but in this vicinity glacial gravel and a few small bowlders
occur that far south. Between the Cannon Ball and Heart rivers
glacial bowlders are found as far west as Elgin, or within 12 miles
of the western border of Morton County. In general the drift
margin between the Killdeer Mountains and the South Dakota
line lies from 40-60 miles west of the Missouri River.
Thickness of the ice sheet —In the vicinity of Berg in northeastern
McKenzie County there are twelve or fifteen high buttes, known
as the Blue Buttes, which are irregularly distributed over an area
of 15 or more square miles. Many glacial bowlders occur on top
of these buttes at an elevation of over 2,700 feet above sea-level,
or 1,000 feet above the Missouri River only 6 miles to the east.
Son
THE PRE-WISCONSIN DRIFT OF NORTH DAKOTA
Since the buttes rise nearly 500 feet above the surrounding upland
the ice sheet probably had at least this thickness in order to over-
Another
ride them and deposit bowlders on their summits.
vIOYLG YON Ur ourvesopy JUoMIeI]Y pur iylIp uIsuoosTAA-oAd Jo uIsIeUI surmoys deyy—6 “ong
NDILD {Anoss!
esc ee Teaopeo + Id $ |= QUIOAO'!W
tdlug ulsuodsi\r-
Satw gO WW JUOWDLY
40 Apes nog
\
ihislyadanik
\
532 A. G. LEONARD
explanation for the presence of the bowlders on top of the high
buttes is that the ice upon encountering these obstructions was
buckled up as it passed over them. But it seems more probable
that the ice sheet which was able to push across the deep valley of
the Missouri River and advance 40-60 miles beyond was thick
enough to submerge the Blue Buttes and pass on over them. The
terminus of the continental glacier was not far from 15 miles south
of the Blue Buttes, since the ice advanced only as far as the Kill-
deer Mountains. Back about 15 miles from the edge the ice sheet
therefore doubtless had a thickness over the upland plain of con-
siderably over 500 feet. The ice which filled the Missouri River
Valley must have had locally a thickness of 1,000 feet or over.
Age of the older drift—That the drift west of the Missouri
River is much older than the Wisconsin drift is evident from the
great amount of erosion it has undergone. Over much of the
region the finer materials of the till have been swept away, leaving
only bowlders and gravel. The older drift also differs in color,
being considerably darker than the Wisconsin. ‘This pre-Wisconsin
drift has commonly been regarded as Kansan and there is perhaps
more reason for referring -it to the invasion of the Kansan ice
sheet than any of the other early ice invasions.
The drift north of the Missouri River and west of the Altamont
Moraine appears to be younger than the drift south and west of the
river. It has undergone less erosion and resembles the typical
Wisconsin till in color. Calhoun believes that the drift of north-
eastern Montana is of Wisconsin age, and on his map this drift
is shown as extending to within about 40 miles of the North Dakota
line.’ The extra-morainal drift north of the Missouri River in
Williams County is undoubtedly continuous with the drift sheet
west of here in Montana, in which case it is probably of Wisconsin
age, and belongs to the Early Wisconsin stage.
li this view is correct, there are three drift sheets in North
Dakota—the Late Wisconsin east of the Altamont moraine, the
Early Wisconsin west of the moraine and north of the Missouri
River, and the Kansan drift west and south of the river.
* Fred. H. H. Calhoun, “‘The Montana Lobe of the Keewatin Ice Sheet,” Prof.
Paper No. 50, U.S. Geol. Survey, 1906, pp. 52-57.
EVOLUTION OF THE BASAL PLATES IN MONOCYCLIC
CRINOIDEA CAMERATA. II
HERRICK E. WILSON
United: States National Museum, Washington, D.C.
PAK
2. CHANGES PRIMARILY MODIFYING THE RELATIONS OF PLATE
CONTACT AND POSITION
The second series of changes, those which modify the primary
position and relation of the basals and radials, will now be con-
sidered. These are: (a) reduction and compensating growth; (0)
enlargement and compensating reduction; (c) plate division;
(d) plate migration; (e) plate interpolation; and (f) anchylosis.
a) Reduction and compensating growth—Reduction, or the
diminution in size of a plate, may be either a function of the absorp-
tive ameboid cells (see p. 502), or due to inhibited growth (atrophy).
That is, the absorption of a fully outlined plate may take place,
as in the absorption of the anal and oral plates in Aniedon, or a
continuous diminution in development to a former standard of
size may result in the atrophy and final disappearance of a plate,
as in the great reduction of the basals in Pisocrinus quinquelobus*
and the disappearance of the first costal in some specimens of
Eucalyptocrinus rosaceus? and Alloprosallocrinus conicus. Atrophy
in plate growth may be due either to plate contact, which inhibits
the free branching and anastomosing type of development, or to
some deep-seated morphological change. The simplest form of
inhibition in plate development is that shown in the normal growth
of plates after coming into mutual contact. It is the process which
= IRGC, Bo 0s Lye
2 Ref. 28, p. go, Pl. XI, Figs. 6, 7.
3In Alloprosallocrinus conicus the writer has found that the apparent anchylosis
of the costal plates (see ref. 39, p. 407) is due to the complete reduction of the first
costal.
533
534 HERRICK E. WILSON
gives to the plates their polygonal outline and must not be consid-
ered a form of atrophy. Plate contact does, however, produce
atrophy when the accelerated growth of one plate causes the
reduction in size of some adjacent plate. This type of inhibition
may be termed superficial atrophy, and is apparently the type
just illustrated in the absorption of the first costal in Alloprosallo-
crinus. Atrophy of the other type is apparently the result of
marked internal changes which appear on the exterior in the reduc-
tion of skeletal parts. This form of inhibition may be termed
deep-seated atrophy, and is the type illustrated in the drawing
together of the posterior radials in Pferotocrinus upon the reduction
of the anal plate (PI. III, No. 11.)
SARE
yeaa) ce:
Fig. 6.—Figures showing the reduction of the first costal in AlJloprosallocrinus
conicus: 1 and 2, from specimen No. 9350; 2 and 3, from specimen No. 9357, in the
University of Chicago collection.
With the decrease in diameter of a plate in a closed cycle there
must be (1) a compensating increase in the diameter of some plate
or plates in the same cycle, or (2) a decrease in diameter of some
plate or plates of the apposed cycle; otherwise the symmetry
of the cup will be distorted. The first principle is clearly demon-
strated by the increase in diameter of the first interbrachial plates
in Amphoracrinus' upon the gradual reduction of the proximal
portion of the second anal plate. The second principle is clearly
demonstrated in the reduction of the apposed compound basal and
radial of Zophocrinus.
This form of change might be confused with vertical plate-
splitting followed by anchylosis of the parts to the adjacent plates
if the change were a sudden mutation and no knowledge of the
ontogenetic development obtainable; otherwise the phylogenetic
succession would show the factors involved. If the reduction of a
TARet 32 ps Loy 2URet Oneal sit.
BASAL PLATES IN CRINOIDEA CAMERATA 535
plate in a closed cycle is asymmetrical, the growth of one of the
laterally adjacent plates will be greater than that of the other, and
will, on completion of the reduction, occupy the entire area of
the missing plate. This process is shown nearing completion in
the reduction of the antero-lateral radials in Catzllocrinus,' and the
consequent enlargement of the left posterior and anterior radials,
and in Mycocrinus? in the reduction of the left anterior and dextro-
lateral radials. In Pzsocrinus the principle is diagrammatically
shown in both basal and radial cycles, where, by the reduction of
two basals and three radials, three basals, two radials, and the
radianal are greatly enlarged (Fig. 7, Nos. 1-4).
=
©
Ww
Fig. 7.—Diagrams illustrating reduction and compensating growth in Pisocrinus:
1, hypothetical, ancestral stage; 2-4, based upon specimens in the University of Chi-
cago collection; x=position of first anal plate.
b) Enlargement and compensating reduction.—Plate enlarge-
ment, as we have seen, is due to the activity of the ameboid calcif-
erous cells. In normal, symmetrical development the growth of
the young plates is for a short time more rapid than that of the
body wall, but upon plate contact the increased enlargement of
both plates and body wall is theoretically balanced. If, however, a
plate increases more rapidly than the adjacent plates, and is not
controlled by the inhibiting influence of symmetrical development,
and its accelerated growth is not compensated for by growth of
the body wall, this growth must be compensated for in some other
manner. Accelerated lateral increase of this type in a cycle plate
demands then either (1) the decrease in diameter of some adjacent
plate or plates in the same cycle or (2) the increase in diameter of
some adjacent plate or plates in the apposed cycle and (3) distor-
tion of the horizontal outline of the calyx or various combinations
of the first two of these secondary developments may occur.
t Ref. 6, p. 149, Fig. LXII. 2) Ret. 28) p. 110; Pl. 7, Bigs 4:
536 HERRICK E. WILSON
Accelerated increase of an interpolated plate between cycles or
plate groups demands: (1) the decrease in size of some adjacent
plate or plates, as in the decrease in size of the dextro-lateral radials
in Pisocrinus (Fig. 7), upon enlargement of the radianal, or (2)
distortion of the cup. )
c) Plate division——This process is the splitting of a plate into
two (perhaps more) parts, either during or after the formation of
the primary, formative cell group. Division of a cell group is due
to cell separation, and may or may not be accompanied by cell
division. Division of the plates when they are once formed is due
to the action of the absorptive, ameboid cells. Division differs
essentially from intercalation, in that a fundamentally distinct cell
group is demanded for the interpolated plate. But no matter how
division may take place, apparent evidences of division in the
plates of fossil crinoids must be very carefully investigated before
too much significance is attached to the opinion that division and
not interpolation has taken place.
Division due to absorption is only known to occur during the
absorption of the supporting rods in echinoid larvae,’ and in the
reduction of the radianal in Antedon.? Division or duplication is
assumed by Bather? in the formation of the paired, proximal inter-
brachials in -Actinocrinidae, yet all evidence from the work on
crinoid larvae shows duplication and not division to be the process
involved. Horizontal bisection is assumed by Bather* in ten genera
of monocyclic Inadunata, not including those in which bisection
of the right-posterior radial only occurs. However, when it is
noted how closely the development and migration of the radianal
in the larvae of modern crinoids parallels the development and
migration of the radianal in the Flexibilia,’ there is good reason to
believe that bisection of the right-posterior radial has not occurred,
but that the radianal and subradials are primary or interpolated
(secondary) plates. Vertical splitting seemed beyond question in
Ref. 34, Pp. 340-54-
2 Ref. 27, pp. 52, 53, Pl. 5, Fig. 11.
3 Ref. 3, p. 34, fifth notice.
4 Ref. 6, pp. 112, 144.
5 Ref. 16, p. 332, 333:
BASAL PLATES IN CRINOIDEA CAMERATA 537
the formation of the compound, left-posterior radial in Anomalo-
crinus,’ yet Springer? has shown it to be an abnormality, due per-
haps to plate fracture There are, it is true, certain conditions
surrounding apparent cases of plate division which lead us to
believe that division and not interpolation has occurred. If, for
example, two plates of the same cycle occupy the approximate
area of one plate in that cycle, if they mutually fulfil the require-
ments of but one plate in that cycle, and if in the obliteration of
the intervening suture a plate would be formed indistinguishable
from the other four undivided plates in that cycle or from the
morphologically undivided equivalent of that plate in a closely
related ancestral genus, division would seem the only logical con-
clusion. But this conclusion is by no means proved. In the
light of phylogenetic and ontogenetic development as ascertained
from fossil crinoids division is very uncertain, for we cannot see
the process taking place. Furthermore, if division had occurred
anchylosis of the parts to the adjacent plates might take place and
either complete absorption with compensating enlargement or
migration would have to be called upon to explain the appearance
of the new suture. Thus, no matter how carefully we attempt to
ascertain the fact that division has occurred, the factor of inter-
polation will usually appear as an alternative. Only through
careful observation, in modern larval development, of plates not
destined to obliteration in the adult stage can this process be
satisfactorily determined.
d) Plate migration—Any shifting which brings a plate, as a
unit, into a new relation of contact and position with plates of the
adjacent cycles, or of adjacent plates in the same series, may be
termed a migration. For simplification in the discussion, the dif-
ferent types of migration may be broadly separated into two
divisions: simple migrations, or those unattended by movements
of the sarcode; and complex migrations, or those dependent upon
movements of the sarcode. Of the simpler forms, three types
occur: portional migration, cell-group migration, and simple plate
migration.
2 IRGE, Bip lewd IUD, jo, Qs TBI, MO), Os WEB
2 IRI, BA. De Divs. 3 The italics are the writer’s.
538 HERRICK E. WILSON
If the absorption or atrophy of one side of a plate and the
growth on the opposite side are approximately equal, the plate
would appear to be shifting as a whole, although actually stationary
in part. This type of migration may be called portional migration,
and is the type illustrated in the shifting forward of the postero-
lateral basals in Xenocrinus and sometimes in Eucalyptocrinus and
Callicrinus.
One form of cell-group migration involving the approximation
and fusion of two groups into one would occur, if in the previous
development of phylitic compression of characters anchylosis were
to be carried back into the embryonic period. Thus, anchylosis
which appeared as an adult character in early times might appear
as an embryonic character in a later stage of development, and
cause fusion of the formative cell groups. It is suggested that this
type of fusion might be responsible for the interradial development
of the two larger infrabasals in Antedon.‘ That cell groups as such
may migrate in response to physiological stimuli from changed
environment without any such evolutional change is also possible,
and experimental evidence has been obtained to substantiate this
hypothesis.” |
Simple migration, after plate formation, without tortion or
other movement of the sarcode, seems from the very nature of
plate growth (see p. 501) to be impossible. This opinion is appar-
ently substantiated by the system of migration of the anal plate in
Antedon, and of the radianal in Promachocrinus* and Hathrometra,*
and by the development of the posterior radials in Antedon upon
the introduction of the anal. Equal spacing of the radials and the
anal in the hexagonal stage of Antedon is not apparent; on the
contrary, the space separating the postero-lateral and antero-lateral
radials is much greater than that separating the postero-lateral
radials and the anal. As the plates increase by branching and
anastomosis, the adjacent margins of the anal and the postero-
lateral radials meet and assume a finished appearance (Fig. 10)
before the postero-lateral and antero-lateral radials meet. For-
ward shoving of the postero-lateral radials into this unoccupied
t Ref. 8, pp. 288, 280. 3 Ref. 16, p. 332-
2 Ref. 26, p. go. 4 Ref. 24, pls. 8-12.
BASAL PLATES IN CRINOIDEA CAMERATA 539
area by growth pressure would be expected, but it does not occur.
On the contrary, the posterior radials either assume an asym-
metrical outlfne as in Antedon, most of the hexagonal Camerata
(Pls. II-III), and many of the Fistulata, or the continued widening
must be compensated for by accelerated growth of the sarcode in
the posterior region. Since no better opportunity for simple plate
migration could be conceived, and since it does not in this case
occur, there is little reason for believing in its existence.
Complex migrations consist of plate shiftings induced by accel-
erated growth, tortion of the body wall, in either local or broad
areas, which distorts the normal space and contact relation of
plates. This form of migration is diagrammatically shown in the
carrying up by elongation of the anal tube of the anal in Antedon,
and of the radianal in Promacocrinus and Hathrometra. Where
the anal and radianal, being more firmly attached to the viscera
than to the adjacent plates, are bodily lifted out of the cup into
the tegmen by the accelerated growth of the hind-gut, this process
is the one which undoubtedly explains the migration of the radianal
in all fossil crinoids. A more common form of complex migration,
and one shown in many groups of crinoids, is that which results
in the formation of biserial from uniserial ossicles in the arms.
e) Plate interpolation—This process may be defined as the
interpolation of some plate or plates, of primary or secondary
derivation, between any plates forming the primitive crinoid cup
and its appendages. It is one of the most common forms of evolu-
tion found in the crinoidea, and may be broadly separated into
two groups: primary interpolation, or the development of primary
or secondary plates zz situ from a primary or secondary formative
cell group; and secondary interpolation or migration. Only the
first type need here be considered, as plate migration has already
been discussed. Primary interpolation is the only known method
by which additional stem ossicles appear; the new ossicles devel-
oping either between the base and the adjacent stem ossicles, as
in the Inadunata and Camerata, or between other stem ossicles,
as in the Flexibilia. In the development of cirri, primary inter-
polation is the rule, the interpolation taking place at the proximal
end of the appendage. Here too belong the development of the
540° HERRICK E. WILSON
perisomic" interbrachials, of the ambulacrals between the orals and
interambulacrals, and of the peculiar plates appearing between
the basal and radial cycles of Acrocrinus.? Interpolation in the
basal cycle is known in but two genera. In Sagenocrinus and
Homalocrinus the radianal is incorporated in the basal cycle, and in
Sagenocrinus especially it assumes the appearance of a basal plate.
Interpolation in the basal cycle, being well established in at least
two instances, seems very rare, yet this may be due entirely to our
lack of knowledge, for the evolution of the radianal plate in the
Flexibilia leads one to believe that it appeared in its primitive
state in the basal cycle A discussion of interpolation in the
radial cycle has been purposely omitted in the preceding citations,
as it belongs more properly in a discussion of the origin of the anal
plate, where it will be fully considered.
It appears then that every cycle of plates excepting the infra-
basals, and every series excepting the brachials, are affected by
interpolation, and even in the brachial series Clark* has evidence
which points strongly to interpolation. There is then a possibility
that every plate cycle and series may be subject to interpolation,
but this point is not of immediate consequence and need receive
no further attention.
Interpolation in the calyx may demand (1) a reduction in some
adjacent plate or plates of the same cycle or group, with or without
oblique development of the plates,> as in the reduction of the
posterior radials and oblique development of the radial cycle in
Antedon upon interpolation of the anal plate; (2) an increase in
diameter of some adjacent plate or plates in an apposed cycle or
group, with or without trunkation, depending upon the alternating
or superimposed position of the interpolated plate, as in the enlarge-
ment and trunkation of the posterior basal in some of the Camerata
t Ref. 16, p. 330.
2 Ref. 39, pp. 805-10, Pl. 53, Figs. 1-3, 4-9, and 10a, b.
3 Ref. 31, p. 493, Pl. 5, Fig. 9.
4Refs 13) purr:
5 Oblique development is here used in reference to the displacement of either the
proximal or distal ends of a plate, from the vertical axis of the cup and not from
the planes of pentamerous symmetry.
BASAL PLATES IN CRINOIDEA CAMERATA 541
and Fistulata upon interpolation of the anal plate, and broadening
of the radials without trunkation upon interpolation of interbra-
chials, as in many of the Camerata; (3) increase in the body wall,
as is shown in the lengthening of the calyx of Acrocrinus upon
interpolation of the extra plates between the basals and radials;
(4) interpolation of an extra plate in an adjacent cycle or group
to satisfy the demands of plate alternation; (5) deformation
of the cup; (6) various combinations of the first four effects
named.
f) Anchylosis —The process of anchylosis is provisionally placed
under this group of processes, because of its intimate association
with certain modifications of plate contact and position which cast
some doubt upon the propriety of assuming it to be a result and
not the cause of those modifications. This fact is shown in the
following section.
ANCHYLOSIS: ITS ANTECEDENTS AND CONSEQUENCES
I. ANCHYLOSIS AND REDUCTION
Anchylosis is the most potent factor operative in the obliteration
of sutures, and while it has been discussed as a simple ontogenetic
process, its antecedents and results have not been considered.
The expression ‘‘reduction and anchylosis,”’ so commonly used in
the description of brachials, means anchylosis following and depend-
ing upon reduction, but whether or not this usage is morphologically
correct is not clear to the writer. Anchylosis may take place
without reduction, or reduction without anchylosis, although the
former is not common. Anchylosis may perhaps be either preceded
or followed by reduction, but the writer is inclined to believe that
when anchylosis is preceded by reduction the reduction is phylo-
genetic, and that in ontogenetic development anchylosis is followed
by reduction. That is, plates which will appear in the adult as a
reduced anchylosed unit are in ontogenetic development up to the
time of anchylosis the equivalent of the other plates in the same
cycle or series, and with anchylosis inhibition of growth causes the
reduction of the compound plate. This inhibition of growth may
be due either to deep-seated atrophy in local areas or to local
superficial atrophy.
542 HERRICK E. WILSON
The first change of interest in anchylosis of basals is the change
of plate outline, from the pentagons through a heptagon to a hexa-
gon. With lateral anchylosis of two basal plates, the pentagons of
the basals are merged into a heptagon, with a re-entrant angle
where the supported radial interlocks with the supporting compound
plate. Upon further development, absorption decreases the angle
of the radial plate, causing it to assume, first a lower angle, then a
proximally convex outline, and finally, by complete absorption, a
straight angle. At the same time, by increased deposition along
the adjacent basal margin, the re-entrant angle of the heptagon is
gradually filled, the filling comforming throughout with the reduc-
tion of the inserted angle. The final step is the change of the
heptagon to a hexagon.
At some time either before, during, or after anchylosis, a
remarkably persistent reduction of the compound plate or its
component parts occurs: This reduction is parallel to the line of
sutural closure, and is sometimes accompanied by reduction in the
proximal diameter of the directly supported radial. From the
principles set forth in the discussion of reduction and compensating
enlargement, either compensating enlargement of the adjacent
plates must take place or distortion follow the reduction. When
only one pair of basals is anchylosed, as in the Xenocrinus, etc.,
and the Calyptocrinidae, the reduction is bilaterally symmetrical;
the basals adjacent to the reduced plates are equally enlarged, and
the reduction is apparently not due to deep-seated causes and
affects only the basal plates and the proximal margin of the apposed
radials (Pl. II, Nos. 2,7). When two pairs of plates are anchylosed,
as in the Stephanocrinidae, Pentremitidae, and Platycrinidae, the
problem is not so simple, for on one side the compound basals are
mutually apposed, and the intervening suture meets the center of
the proximal margin of the radial. If the reduction of the com-
pound basals is asymmetrical and occurs only on the sides opposed
to the simple basal, no distortion in symmetry is necessitated. If,
however, the reduction is symmetrical, there must be a distortion
in symmetry of the cup, for there is no basal to enlarge where the
compound plates are mutually opposed. In the Platycrinidae the
reduction is asymmetrical, and is perhaps due to superficial atrophy.
BASAL PLATES IN CRINOIDEA CAMERATA 543
The simple basal is in general symmetrically enlarged, and the
base is occasionally a regular pentagon.
In the Stephanocrinidae and Pentremitidae the reduction of
the compound basals is bilaterally symmetrical, and is usually
accompanied by reduction of the radials directly supported by the
compound plates. This reduction is compensated for on the anterior
side by lateral growth of the simple basals and the radials obliquely —
supported by it. On the posterior side, however, distortion has
taken place. If absorption had caused the reduction, either plate
shoving or shrinkage of the sarcode would be necessary to keep
the plates in contact; but plate shoving is apparently impossible,
and shrinkage of the sarcode improbable. Upon comparison of
the ornamentation in the reduced and unreduced radials in Ste-
phanocrinus, another change seems to have taken place. The
neural ridges of the reduced radials are fused, farming a single
broad ridge, which apparently indicates that the underlying nerves
are in closer relation than in the other radials. The reduction
seems, then, to have been caused by the inhibition of lateral expan-
sion in the sarcode in the reduced areas, and not to absorption, and
isa very good example of deep-seated atrophy. In the three-
basaled, hexagonal Camerata, anchylosis and reduction of the basals
are complicated by the appearance of the anal plate, and cannot
now be considered.
2. DELAYED ANCHYLOSIS
In many genera, especially of the hexagonal Camerata, anchy-
losis takes place at such an early period in development that no
trace of the immature forms with unanchylosed basals is preserved.
The only hope, then, of locating the missing suture is by delayed
anchylosis, or characteristics of ornamentation. Ornamentation
has, however, received so little study, and the subject is so broad,
that the writer cannot at present give it adequate consideration.
Examples of delayed anchylosis, however, are not unknown, and a
number of cases will be cited in the latter part of this paper.
Delayed anchylosis is simply a nascent stage of anchylosis, due
to the inhibition of activity in the ameboid calciferous cells. It
may appear in the form of internal or external grooves, or in its
544 HERRICK E. WILSON
completeness as an unchanged suture. In the latter case, it is in
the Camerata always accompanied by the inserted angle of the
apposed radial. In the pentagonal Camerata the reappearance of
a suture or group of sutures would unhesitatingly be described as
cases of delayed anchylosis. In the hexagonal forms, however,
doubts might arise concerning the reappearance of the anterior
suture in the three-basaled genera and of the right-anterior suture
in the two-basaled genera, since such reappearance would, according
to Wachsmuth and Springer, indicate the presence of six basal plates
(pp. 492-93). There might also be some question as to whether
these reappearances are due to delayed anchylosis or resorption;
but until more light can be thrown upon the problem of sutural
reappearance by reabsorption of the intrasutural deposit, these
abnormalities may well be ascribed to delayed anchylosis.
3. ANCHYLOSIS AND THE PHYLOGENETIC REAPPEARANCE OF SUTURES
Anchylosis of the basals, as far as we now know, is an onto-
genetically repetitive process, confined to plates and not taking»
place as a result of cell-group fusion. The basal sutures are always
present in ontogenetic development, and constitute phylogene-
tically a plane of weakness in the compound plate. This is appar-
ently not true of the infrabasals, at least in modern forms, as is
shown in the interradial development of two of the infrabasals in
the embryo of Antedon. Atavistic reappearance of sutures, by
delayed anchylosis, is a possibility, but the cenogenic or phylogenic
reappearance of a suture lost through anchylosis is another question.
The skeleton of the Echinoderm is deposited in the midst of living
tissue and remains under the full control of the ordinary processes
of growth, reabsorption, and modification by living tissue.t The
partial or total absorption of plates, the shifting of sutures, and
the reabsorption and modification of the basals in the formation
of the centro-dorsal are sufficient evidence of this statement. It
seems possible, then, that under the conditions of physiological
disturbance (loss of vitality) common in the paracme of develop-
ment,’ failure of anchylosis or reabsorption of the intrasutural
deposit might take place, and the sutures reappear as phylogenetic
t Ref. 7, p- 350- 2) [bid., Pp. 350.
BASAL PLATES IN CRINOIDEA CAMERATA 545
characters; but we have no evidence of such a reversion, and, until
such evidence is brought forward, theories of descent demanding
the reappearance of lost sutures should be carefully scrutinized.
DEVELOPMENT OF THE INTESTINE AND THE CONSEQUENT
ZONES OF POTENTIAL WIDENING
“Tn all the Echinoderm classes it is the digestive tube that
controls any departure from pentamerous radial symmetry.”’
This statement by Clark" may perhaps be too sweeping in extent,
especially when we consider the potency of atrophy and compen-
sating hypertrophy (p. 533) in distorting symmetry; but the fact
that the digestive tube is one of the most powerful factors in
distorting symmetry cannot be too strongly emphasized. The
most striking and therefore the most widely known effect of this
power is that shown in the various distortions of the mouth and
ambulacral grooves by excessive growth of the hind-gut. These
tegminal distortions have been so frequently described that there
is no necessity of reviewing them here; distortions produced by
the intestine in the basal and radial cycles have, however, received
too little attention.
In the development of the digestive system in Antedon the
gastric sack is elongated horizontally into a form somewhat resem-
bling the human stomach, having a large end into which the funnel-
shaped oesophagus opens, and a small end with a caecal termination,
which is the potential intestine. Upon further development the
intestine is also horizontally prolonged, and coils to the right,
around the stomach; in the space left for it by the enlargement of
the calyx;? before the coil is completed, however, the anal appears
and the intestine directs itself toward that plate. The pressure
_exerted by the intestine upon the anal tends to keep separated the
posterior radials and prevents the right-posterior radial from
encroaching upon the anal. Soon, however, the intestine turns
upward and carries the anal with it into the tegmen. The
thrust exerted by the outward growth of the intestine which dis-
places the anal and also the radianal (see p. 538) must not be con-
Neh T0;) D152.
2 Ref. 12, pp. 227-28. 3 Radianal. See Ref. 16, p. 333.
546 HERRICK E. WILSON
sidered as a gentle pressure, nor the displacement of these plates
as a gentle process, due only to their much closer association with
the intestine than with the surrounding plates. The outward
push of the intestine is in proportion to the strength of the calyx
walls a powerful force, capable of inhibiting plate growth and of
greatly distorting the relations of plate contact and position.
In the recent works of Springer and Clark attention has been
called repeatedly to the remarkable parallel between the ontogenetic
migrations of the radianal in modern crinoids and its phylogenetic -
migration in fossil forms. Since the migration of the radianal in
recent forms is caused directly from its intimate association with
the hind-gut in its upward growth, there can be no doubt that such
an association existed in the ancient crinoids, and that the tendency
for shifting the radianal gradually increased and the association
became so firmly established that the radianal is now completely
withdrawn from the cup in individual development.
The radianal in the early Flexibilia is incorporated in the basal
cycle below the right-posterior radial, and probably appeared in
that position in the ancestors of the Flexibilia.2, The outward push
of the developing intestine was then directed obliquely to the
right against the radianal and in the succeeding stages shoved and
pulled this plate upward and to the right into the posterior inter-
radius and out of the cup. Furthermore, in Sagenocrinus* it
permitted such an enlargement of the radianal that the right mar-
gin of the posterior basal was shoved to the center of the posterior
interray. This change is of especial interest in the study of basal
plate evolution, as it shows one method of obtaining a posteriorly
directed basal suture, such as is exhibited in all genera of Camerata
having a hexagonal, tripartite base.
This apparent digression from the subject of basal plate evolu-
tion in the Camerata—a group in which, as far as we now know, a
radianal plate never appeared—is for the purpose of bringing
clearly to mind the powerful effect of the growing intestine and the
presence of zones of potential weakness in the calyx. These zones
of weakness lie along the posterior interradius in the radial cycle
Reta rhs ao:
2 Ref. 31, p. 430, Pl. V, Fig. 9. 3 [bid., Pl. VII, Fig. 18.
3
F
.
‘
'
BASAL PLATES IN CRINOIDEA CAMERATA 547
and along the right-posterior radius in the basal cycle, and it is to
the latter zone that especial attention is called. Wachsmuth and
Springer have noted this zone of potentiality in but one instance
(description of Fig. I, No. 7, of this paper), although it seems the
only zone of potentiality in the basal cycle which can logically be
accounted for. Pressure from the end of the developing hind-gut
must from the necessity of its position be directed obliquely to
the right against the posterior interradius, and any lateral pres-
sure of the gut must be directed against the right side of the
calyx, the two combining to shove the right side outward and
away from the left side. Thus the stress produced by this shove
would naturally fall along the right-posterior basal suture, as this
is the nearest suture or plane of expansion adjacent to the posterior
interradius within the zone of pressure exerted by the hind-gut.
ORIGIN OF THE ANAL PLATE
Comparison of the cup and tegminal structures in the Bato-
crinidae and Platycrinidae shows that a very long period of time
must have elapsed, or very rapid evolution have taken place, before
such a highly specialized form as Tanaocrinus could have originated
from any of the early Platycrinidae. Since Tanaocrinus is an early
Silurian (Richmond) genus, relationship can be established with
the Platycrinidae only through Ordovician or pre-Ordovician ances-
tors; therefore, if Tanaocrinus is related to the Platycrinidae, it
must have been derived from a form having a simple, pentagonal,
five-basal cup. The primary step in the evolution of this form
into Tanaocrinus would be the introduction of the anal plate
into the radial cycle, thus giving to the cup its hexagonal outline,
and inducing in the basal-plate cycle a remarkable series of modifi-
cations. The questions then arise: How do we know that the anal
was a secondary and not a primary plate? At what period in the
ontogenetic development of the Camerata was it interpolated in
the radial cycle? Where did it originate? And what changes
followed its interpolation? ~ It is generally agreed that the anal
plate in the hexagonal Camerata is of secondary origin. If this is
true, the statement just made concerning the ancestry of Tanao-
crinus is undeniable, for by eliminating the secondary plates of
548 HERRICK E. WILSON
that genus and restoring the orals an ideal larval or ancestral
form will appear. If, however, the anal plate is a primary plate
in the radial cycle, a different line of descent is indicated.
In the ontogenetic development of the skeleton in the living
Antedon the anal plate is interpolated after the basals and orals
have formed closed cycles, and before the radials are laterally in
contact. As the anal expands by lateral and proximal growth, it
comes into contact with the posterior radials and the posterior
basal; but this happens before the distal margins of the basals
are completed and while the radials are still separated from each
other. Since growth in the anal plate and the posterior radials
does not cease upon their coming into contact, shoving of the
posterior radials in the direction of the unoccupied lateral areas
might be expected. This, however, does not occur. On the con-
trary, the crowding results in a partial inhibition of growth in the
apposed margins, and a marked asymmetry results in the outline
of the posterior radials, especially in the right-posterior radial. If
comparison is now made between Antedon in this stage of develop-
ment and the early Camerata having a hexagonal base, a striking
similarity is seen in the development of the basals, radials, and the
posterior side of the calyx. The posterior radials in both forms
are asymmetrical and narrower than the anterior radials, and
the asymmetry is due to the diminution of the posterior side of the
plates, the distance between the center of the radial facet and the
plate margin being less in the posterior half than in the anterior
half. If comparison is then made between the relative position of
axial lobes and radial plates in pentagonal and hexagonal Camerata,
a further distortion is noted in the hexagonal forms. The lobes of
the canal in the pentagonal forms occupy an interradial position,
while either two or three of the lobes in the hexagonal forms occupy
a radial position. These facts show that there is a distorting factor
present in the posterior side of the cup. When it is considered
that pentamerous symmetry is the rule in Echinoderms, and that
sutural symmetry based upon the hexamerous plan only appears
in the basal cycle with the appearance of the posteriorly
directed basal suture, there seems to be no other alternative
than that the anal plate is the distorting factor, and that it has
BASAL PLATES IN CRINOIDEA CAMERATA 549
developed secondarily in the radial cycle, or has migrated into that
position.
The origin of the anal plate is as yet an unsettled question, but
there are several possibilities which may well be considered. It
may have originated as a secondary plate in either the basal or
oral cycle. It may have developed as one of a brachial series, or
an interbrachial cycle, or it may have originated as a separate plate
in the radial cycle. Origin in the basal or oral cycles is clearly out
of the question, for we know of no plates in either cycle from which
it could have originated. Assumption of origin as a brachial, which
is Bather’s explanation for the origin of the anal plate in the Fis- ,
tulata,t is without foundation in the Camerata.
Origin as one of an interbrachial series of the ordinary type is
also improbable, for although these interbrachials are present in
Tanaocrinus, Xenocrinus, and Compsocrinus, they are clearly formed
at a later stage of development. Origin as a first interbrachial,
that is, one of an interbrachial series interpolated between the
radial plates, has been seriously considered by Carpenter’ in a
comparison of Xenocrinus, and some of the dicyclic Camerata,
with Antedon and Thaumatocrinus renovatus; and while such a
cycle may have existed and the lateral plates have atrophied, there
has been found no record of such a cycle in the monocyclic Came-
rata. This, however, does not preclude the idea that the anal
series may have been so interpolated, and that the lateral plates
which appear in some of the dicyclic Camerata have been the
result of reduplication.s Let us examine the ornamentation in the
anal series of Compsocrinus and Xenocrinus, and see if this may
not throw some light upon the question. Bather, in calling atten-
tion to the anal ridge in the Reteocrinidae, Glyptocrinus, etc., says,
“The anal ridge is connected with the ridges that unite the posterior
basal to the right- and left-posterior radials, and this indicates
that an axial cord passed up it to govern the motions of the anal
tube.’’4 That this ridge does so indicate the presence of an anal
nerve seems beyond question, for in comparing the ornamenta-
tion in Xenocrinus and Compsocrinus with the nervous system of
t Ref. 4, pp. 319-31. 3 Ref. 16, p. 338.
2 Ref. 10, pp. 38-406. AIRE, O, [Dp 110),
55° HERRICK E. WILSON
Thaumatocrinus a striking similarity is discovered. In Thau-
matocrinus the interradial arms are innervated by secondary branches
of the axial cord, which originate slightly above the point of bifurca-
tion of the basal cord, quickly join, and pass up the interradial arms,
while the main branches pass up to the radials (Fig. 7, No. 2).
In Xenocrinus and Compsocrinus (Fig. 8, No. 1) the anal nerve
ridge arises at the point of bifurcation of the axial trunk ridges in
the posterior basal, and there can be little doubt that the branching
of the underlying nerves took place in the same manner as they do
in Thaumatocrinus. The parallel here is so close that the writer
was at first inclined to the belief that the interpolation of the anal
series in the Camerata is of the
same type as the interpolation of
the interradial arms in Thaumato-
crinus. In Thaumatocrinus' the
‘“‘interradial”’ radials appear very
early in the ontogenetic develop-
ment as narrow plates separating
Fic. 8.—Diagram showing the the radials and gradually increase
course of the radial and anal ridges 49 the size of the true radials. An
in Comprcrins andthe DROS Chection to this form of develop
Compsocrinus harrisi (based upon ment has been stated by Bather, on
Wachsmuth and Springer); 2, the ground that no primitive genera
Thaumatocrinus renovatus (after Car- : °
aes have been found in which the anal
penter); course of nerves based upon
dissection by the writer. plate appears aS a Narrow linear
plate. This objection, however, is
not formidable, for the change may have been a discontinuous
mutation, or may have taken place during periods of retreat of .
the sea. Ulrich believes that most mutations have so taken ae
for he says in the “Revision of the Paleozoic Systems”: “
almost invariably we deal with the nearly finished product a a
process of mutation that was begun and established before the
new phase invaded areas now accessible to the student of fossil
faunas.’
«See Ref. 16, p. 337.
2 Ref. 3, fifth notice, p. 37.
3 Ref. pp. 498-501.
BASAL PLATES IN CRINOIDEA CAMERATA 551
The logical sequence of events based upon the Thaumatocrinus
theory would be the interpolation of the anal plate in the radial
cycle and serial development of the succeeding anals. But when
this sequence of events is applied to the pentamerous, monocyclic
Camerata difficulty is immediately encountered. Either these
forms have lost their true anal plate and the anal now appearing
in them is the homologue of the second anal in the hexagonal
Camerata, or they have developed along a different line of evolution
from the hexagonal forms. But before taking up these questions let
us examine this theory of interpolation more closely.
Stratigraphically the pentamerous base precedes the hexamerous
base, and it seems scarcely possible that a hexagonal form which
could give rise to both Glyptocrinus and Tanaocrinus could have
been living in the ocean basin during pre-Ordovician and Ordovician
times, and that only those forms having lost the anal plate should
have migrated into the epicontinental seas during the Ordovician,
while those having the anal plate were withheld until Silurian
(Richmond) times. This is apparently carrying the theory of
selective action too far to be believed. Again, the embryological
evidence shown in Thaumatocrinus may not be reliable. We have
noted that the radianal in Promacocrinus originates to the left of
the right-posterior radial; furthermore, we know that the radianal
appears in the more primitive crinoids in a subradial position.
There has been not only a progressive upward shifting of the radi-
anal in these groups, but there has been apparently a progressively
upward shifting of its point of origin. Embryology does not repeat
all the ancestral characteristics step by step and then eliminate
them in a different fashion in producing the various genera and
species; certain characters which are gradually being eliminated
phylogenetically are probably, in Crinoidea, the result of a progres-
sively increasing inhibition of plate development in the larva,
which ends in the complete obliteration of the plate. Since embry-
ology does not repeat all the ancestral stages, and does in this
case permit of changes in the position of origin of a plate, there is a
possibility that the “‘interradial”’ radials in Thaumatocrinus did
t For a more complete discussion of this phase of development based upon a wide
series of observations, see Ref. 23, Chap. III, ‘‘Recapitulation.”
552 HERRICK E. WILSON
not originate in the position in which they now originate, and too
much dependence should not be placed upon this character. The
evidence presented by fossils is fixed, although often wrongly inter-
preted, and until stronger evidence is submitted it is well to hold
closely to that presented in the stratigraphic succession.
Stratigraphically the pentamerous base preceded the hexamerous
base, and when we consider with this the evolution of the two-
basaled, hexagonal Camerata, a more logical theory of development
for the anal plate is presented. In this short-lived group we have a
very rapid evolution from some platycrinid stock. The anal plate
in Platycrinus originates in the posterior interray between the distal
margins of the radial plates, while the anal plate in Dichocrinus
projects above the level of the radials and costals and bends sharply
inward toward the anal tube; its distal portion is reduced, and, if
it were separated from the enlarged proximal portion and slightly
modified, could not be distinguished from the anal in Platycrinus.
Enlargement and downward growth of the anal seems then to have
occurred, and a different theory is offered for the interpolation of
the anal plate.
This theory for the appearance of the anal plate is, then, that
the anal plate is of secondary derivation; that it was interpolated
phylogenetically after closure of the radial cycle, but ontogenetically
after the basal had formed a closed cycle and before the radials
had come into contact. The cup in this stage of development is
in a flexible condition, and readjustments can readily be made.
Development of the anal plate in this position requires no true
migration to come into contact with the posterior basal; portional
migration, or proximal growth with distal inhibition in the younger
stages, will produce the Tanaocrinus type of anal, while distal
growth alone is necessary to produce the Glyptocrinus type of anal.
The stimulus which kept the radials apart and permitted this
downward growth of the anal plate was the demand for room on
the part of an enlarging hind-gut, and it is this stimulus which has
caused some of the most remarkable changes in crinoid evolution.
Additional plates in the anal series were probably added as needed,
for protection of the anal tube, and no slipping downward of a
completed series of anals is required. In considering this change
BASAL PLATES IN CRINOIDEA CAMERATA 553
we must remember that we are not dealing with a completed model
in which the plates are of fixed and unchangeable size, and in which
every change of plate position must be accompanied by an entire
readjustment of the adjacent plates; we are dealing with a growing
organism in which there is a certain amount of flexibility in adjust-
ment by plate growth.
If this theory for the interpolation of the anal plate is correct,
the first anal plates of Glyptocrinus, Platycrinus, and Dichocrinus
are homologous; and in further developing the theory for the
evolution of basal plates this view will be followed.
[To be concluded]
DIFFERENTIATION IN INTERCRUSTAL MAGMA BASINS
ALFRED HARKER
Cambridge University
Dr. N. L. Bowen’s comprehensive article on “The Later Stages
of the Evolution of the Igneous Rocks,” issued as a supplement to
the last volume’ of this Journal, will be hailed with satisfaction
by all petrologists, and indeed with gratitude by those who have
the misfortune not to be chemists. It contains the first serious
attempt to deal with the problem of magmatic differentiation
directly from the standpoint of experimental knowledge. In
demonstrating how the course of crystallization may be changed
by the sinking of crystals, or the straining away of liquid from
crystals, or the formation of zoned crystals in isomorphous groups
of minerals, the author scarcely goes beyond actual laboratory
experience, and his conclusions accordingly carry a great weight
of authority. When he proceeds to construct on this basis a general
theory of differentiation, the element of hypothesis is necessarily
introduced, and, as the author recognizes, his argument can no
longer command unquestioning acceptance. It is a very interest-
ing contribution to a discussion which is not likely soon to be closed.
I wish to make a few remarks upon one of the subsidiary issues,
which, however, touches the main theory at numerous points, viz.,
Bowen’s predilection for differentiation 7m situ as opposed to differ-
entiation prior to intrusion. That an appreciable settling down
of crystals may take place after intrusion is not to be denied, but
I think that the experience of any field geologist goes to show that
it is a rare and exceptional incident. Daly has given a list of about
thirty stratified sills and laccolites in which such “ gravitative”’ dif-
ferentiation is believed or conjectured to have occurred, but proba-
bly a critical examination would dispose of many of the examples
cited. In some, such as the Loch Bordan mass in Sutherland, there
is not a gradual transition but a sharp boundary between the several
554
DIFFERENTIATION IN MAGMA BASINS 555
rock types. Bowen remarks that the upper acid magma, remaining
fluid after the lower basic portion has wholly crystallized, may come
to have an intrusive relation to the latter. This would be sufficient
to explain veining of the one rock by the other; but, where an
overlying sheet is separated from an underlying one by a surface
of discontinuity, I can see no explanation but that of distinct intru-
sions. Nor is this explanation necessarily excluded even when
no sharp division is seen, for, under appropriate conditions, a
transitional zone may result from partial admixture. The Sudbury
laccolite is probably a case in point, though I must confess to only a
limited personal examination of the mass. I found no indication of
a regular “composition gradient”’ in either norite or granophyre,
considered separately, while the transitional zone between them
has all the characters of a hybrid rock. The sulphide ore I leave
out of count, as doubtless representing a magma immiscible with
that of the norite. The clear instances of gravitative differentiation
in sills and laccolites of which I have direct knowledge are all in
rocks which must represent very unusually fluid magmas, such as
the analcime-bearing intrusions of Permian age in Scotland. They
are the kind of exceptions which help to prove the rule: viz., that
in an intrusive body of moderate size a prohibitive viscosity soon
puts a stop to the settling down of crystals. Doubtless a laccolitic
mass of very large dimensions retains its fluidity longer, but it is
obviously in a great intercrustal reservoir that the most favorable
conditions for this action will be realized.
Bowen would apply the conception of differentiation in place
to the plutonic rocks of Skye; but the facts, as I see them, abso-
lutely negative such a hypothesis. The peridotite is not found at
the base of the gabbro, but enveloped in the midst of it. The
granite breaks through the gabbro, and, where any approach to a
stratiform arrangement is apparent, does not overlie, but underlies,
the basic rock. In one part the granite has been so chilled against
the gabbro that its margin and the offshoots from it assume the
characters of a spherulitic rhyolite. I infer that the gabbro was,
in this place, not only solid but cold when the granite was intruded.
The large gabbro laccolite itself is made up of numerous irregular
sheets, showing differences in composition and structure, and often
556 ALFRED HARKER
visibly cutting one another. In the peridotite this composite struc-
ture is more strikingly exhibited, and it can be detected in places in
the granite, which isa much more uniform rock. The several compo-
nent sheets are not disposed in an orderly fashion in accordance with
their various densities. Add to this evidence the fact that peri-
dotite, gabbro, and granite all make smaller separate intrusions,
some much too far away from the main complex to have any direct
connection with it, and it will appear beyond dispute that the
differentiation which yielded these various rocks was effected prior
to their intrusion, and therefore in some large reservoir at a deeper
level.
Bowen does not refuse the conception of a deep-seated magma
basin stratified according to density; but he seems to think it an
absurdity that, on that hypothesis, the earlier intruded magmas
should be drawn from the lower levels (p. 73). I will try to remove
his objections. I have already urged' that in order that such a
basin may have a considerable degree of permanence, as it obviously
has, we must suppose some approach to thermal equilibrium
between it and the surrounding crust. This implies a temperature
gradient within the basin approximately like the normal gradient
in the earth’s crust of the region. It implies, further, what I may
call a fusibility gradient corresponding with this normal temperature
gradient. Now, the separation and sinking of crystals, as pictured
by Bowen, goes with a cooling-down of the magma, which terminates
in complete solidification. Any intrusions drawn from the basin
must therefore be consequent upon remelting. The occasion of
this I presume to be a gradual rise of the isothermal surfaces,
which must accordingly become more closely spaced. In other
words, reheating implies a temperature gradient steeper than that
to which the fusibility gradient is adjusted, and it follows that
the lowest layers will first become fluid. I have not attempted to
develop this view of the matter, and should welcome criticism; but
Bowen’s zeal for differentiation in place has caused him to pay little
regard to the possibilities of this alternative.
I am wholly in accord with Bowen in the conviction that alka-
line and calcic rocks are derived from the same primitive magmas
t See especially Compte Rendu XII Congr. Géol. Intern., Toronto, 1914, pp. 205-8.
DIFFERENTIATION IN MAGMA BASINS 557
(p. 59). My belief has been, and is, that the differentiation of
these two great classes of magmas from the common stock and the
separation of them—in general in a horizontal sense—constitute the
first and most important steps in the evolution of igneous rocks.
Why the chemical differentiation should so consistently follow these
lines has been a difficult problem, and it is the more gratifying to be
offered at least a partial answer to the question. Stated broadly,
Bowen’s ideal scheme of differentiation leads first to a series of
calcic rock types and subsequently, if continued, to an alkaline
series. There are qualifications of this rough statement which I
do not go into here; but in general it appears that, if a separation
can be brought about at a certain well-defined stage of the progres-
sive differentiation, it will be a separation between calcic and alka-
line. This separation, I hold, has actually been effected on a grand
scale, and I have sought the immediate cause of it in the action of
crustal stresses squeezing out the residual fluid.
A discussion of this suggestion from the chemical point of view
would be instructive, but here Bowen disappoints expectation.
He dwells on particular cases in which separation has not taken
place at the stage specified, but at a somewhat earlier stage; and
he throws doubt upon the existence of any general regional dis-
tribution of alkaline and calcic rocks, such as Iddings demon-
strated long ago. The fact that, among the younger rocks of North
America, alkaline types characterize the Atlantic slope and calcic
the Pacific, he would explain by supposing that erosion has exposed
deeper levels on the western side of the Rocky Mountains than on
the eastern. He forgets that the contrast of petrographical facies
holds good for the lavas as well as for the intrusive rocks. More-
over, the fact that lava flows still cover vast areas on the western
side, while on the eastern they have mostly been removed, makes it
difficult to accept his statement about the relative amounts of
erosion.
As regards the association of calcic rocks with regions subjected
to powerful lateral thrust, nothing would be gained by traversing
old ground again, but to Bowen or any other unbeliever I will offer
just one consideration. If we examine those crystalline schists
which are admittedly of igneous origin, together with foliated
558 ALFRED HARKER
igneous gneisses, we find that they belong almost exclusively to the
calcic branch. A few exceptions there are, and must be. A nephe-
line syenite may be intruded in a line of faulting during the time
of movement, as in the Langesundsfjord; or it may be crushed and
metamorphosed long afterward by stresses with which it has no
genetic connection, as at Loch Borolan; but these are isolated and
incidental occurrences. The matter is easily brought to the test.
In Grubenmann’s classification, based solely on chemical composi-
tion, the crystalline schists and gneisses of igneous origin are con-
tained in six of the twelve groups. The calcic rocks are in Groups
I, III, IV, and V, which correspond with granites, diorites, gabbros,
and peridotites. They include a rich variety of types, and col-
lectively make up enormous tracts of the earth’s crust. To com-
plete his classificatory scheme the author has been able to produce
various types of alkaline rocks, which scantily furnish forth Groups
VI and VII, but most of them are little more than petrographical
curiosities. In respect of the total bulk of all known occurrences,
these alkaline crystalline schists as a whole are quite insignificant
as compared with any single type in the calcic division.
The striking disparity here noted is only one consideration
among others which points to a peculiar distribution of alkaline
_and calcic igneous rocks in relation to crustal stresses. If anyone
seriously believes that such things are matters of chance coincidence,
there is no more to be said. It is to be hoped rather that chemists,
as well as geologists, will recognize here a real significance, and will
lend their help in the attempt to explain the facts, not to explain
them away.
STRATIGRAPHY OF THE SKYKOMISH BASIN,
WASHINGTON
WARREN S. SMITH
Berlin, Washington
WITH
REPORT UPON PALEONTOLOGY AND PALEOPHYTOLOGY
CAROLINE A. DUROR
STRATIGRAPHY
I, GENERAL AREAL DISTRIBUTION
In general, the rocks of the Skykomish Basin trend in a north-
south direction. This is almost exactly true of the igneous and
metamorphic terranes. Only the sedimentary Swauk and the
tufaceous Keechelus series vary from this general statement, for
they show a trend in general west of north but bending northward
on their northern prolongation. Dawson has remarked this tend-
ency of all the rocks of the Cordilleran system.t The rocks lie
in roughly parallel bands in the north, but are replaced southward
until the granodiorite entirely takes the place of the earlier series
and extends over nearly the entire width of the quadrangle. Igne-
ous rocks greatly predominate in the area, metamorphics and
sedimentaries being approximately equal in amount, and both
being comparatively small. Volcanics make up a smaller division.
These relations will be illustrated by the following classification
table:
Shoqualmuiereranodionitens.... .- 0-64. sees 130.90
iKeechelusyandesitic series: 2-5 44:08 o eee 32.20
versodaygramiterand: Beckler stocks). sequins
HBAS LOMUSCHIS tater Aton ae 2 oer fon Meee gers ea 22.95
Swaulkeisedimentanye Series: <4 ene 56.00
Maloney metamorphic series................. 14.80
Iindexmeranodioniteme- 1 snes ase Bh, 2
SWINSS OUUSKOD QE « oo og oa docs oso saa nos AS Sob ml
1G. M. Dawson, “Geological Record of the NOESY Mountain Region in Canada,”
Bu Geol. Soc. Am., XII (1901), 50.
559
560 WARREN S. SMITH
In the following discussions no effort will be made to subdivide
the metamorphic rocks of a sedimentary origin from those of an
igneous origin, where these are so intimately associated as to make
the subdivision impracticable. However, the schists of the north-
eastern area are easily kept distinct from the metamorphic series
of the northwestern area.
On stratigraphical grounds the rocks readily fall into two
groups: (1) the pre-Tertiary, and (2) the Tertiary. The division
line between these is the most marked unconformity in the Cascades.
We have present a schist, belonging to the pre-Tertiary, which is
cut by quartz and igneous rock dikes, making the oldest or basal
terrane.
This is called the Easton schist, and it forms the metamorphic
terrane in the northeast. No definite idea of its age can be sug-
gested except that it is pre-Ordovician. Fragments of it are
included in the Mesozoic batholiths, and it is more complexly
folded than the Maloney (Gunn Peak) metamorphic series. The next
younger series belongs on paleontologic and correlation evidence
to the Ordovician. It is a series of quartzites, schists, and crystal-
line limestones with associated greenstones, approximately 4,000
feet thick, outcropping in the northwest. Weaver correlates this
series with the Cache Creek series as defined by Dawson. It has
at least one stage less of dynamic history than the Easton and
on lithologic grounds it is believed to be equivalent to Smith’s
Peshastin series of the Snoqualmie area; but its fossil content
identifies it as Ordovician instead of Carboniferous, as the Peshastin
is called by Smith and the Gunn Peak by Weaver. Nothing can
be said of the remainder of the Paleozoic history of the area. The
absence of later Paleozoic and Triassic seems to be general in the
region of the Cascade Mountains. In Jurassic time, however,
there was a notable period of deep-seated volcanic activity, result-
ing in the intrusion of the great Sierra Nevada-Cascade granodi-
orite batholith, possibly the greatest of igneous intrusions.2 This
batholith is represented by two terranes in the Skykomish Basin.
The first is the Tye soda granite in the northeast, and the second
*G. M. Dawson, Ann. Rept. Can. Geol. Surv., N.S., VII (1894), 37B-40B.
?R. A. Daly, Igneous Rocks and Their Origin (1914), p. 53.
STRATIGRAPHY OF THE SKYKOMISH BASIN 561
is the Index granodiorite in the northwest. The Cretaceous is not
represented but is known to occur as a marine series farther north-
ward. Following the Mesozoic batholithic intrusion came a posi-
tive orogenic movement, corresponding to the Laramie revolution,
which left the Cascade area, at the close of the Mesozoic, high
above sea-level.
The Tertiary period opened with a period of continental deposi-
tion in which the Swauk sandstone was deposited unconformably
on the eroded edges of earlier metamorphic rocks. These arkoses
consist of mingled fragments of granitic rock and of schist derived
from the Paleozoic metamorphic series and from the Mesozoic
batholith. Both Smith and Willis consider these arkoses to be
lake deposits, but Weaver more correctly designates them as purely
continental. They show conglomeratic facies and cross-bedding
and vary so markedly in thickness that only the maximum figure
of 4,000 feet is of any significance. They are equivalent to the
lower Puget of western Washington and, on paleophytological
grounds, to the Fort Union of the Montana-Wyoming areas. No
definite information is recorded of the late Eocene and Oligocene,
the gap being succeeded by Miocene andesitic tuff beds. These
are volcanic tuff ejectamenta cut by dike- and sheet-like intrusions
of andesitic composition. We have insufficient evidence to suggest
where these tuffs had their immediate source, but their chemical
resemblance to the Miocene granodiorite suggests forcibly that they
were derived from the same magma. In later Miocene a recurrence
of deep-seated vulcanism took place, resulting in the injection of
the Snoqualmie granodiorite, which is the most important terrane:
present in the area. This batholith, if its texture is to be accounted
for, must have been covered by at least 2,000 feet of rock. In this
cover late Eocene and Oligocene may be included. In latest
Miocene and in early Pliocene the region was planed to a low relief;
a disturbance of isostatic equilibrium followed, which resulted in
the arching up of the Cascade Mountains to a maximum height
of approximately 8,000 feet. Since this Pliocene uplift, canyons
some 5,000 feet deep have been cut in the granodiorite, a fact
bearing witness to the severity of erosion experienced by the
area.
562 WARREN S. SMITH
In the Pleistocene the Skykomish Basin was eroded by valley
glaciers, and the only discernible post-Tertiary volcanic history is
recorded in a thin layer of ash, probably drifted from Mt. Rainier
by prevailing southwest winds. Post-Pleistocene time has not
lasted long enough seriously to change the aspect of the topography
left by glaciation.
II. . PRE-TERTIARY HISTORY
PRE-MESOZOIC
The pre-Mesozoic is represented by two divisions, one of which
is considerably older than the other, and on lithologic grounds is
referred to an equivalency with the Easton schist. The later
division has experienced at least one stage less of metamorphic
history and is of known Ordovician age, on the evidence of fossils
obtained from a cherty phase of the limestone lens outcropping
in Lowe Gulch (D 2), two miles west of Grotto. No evidence of
the exact age of the Easton schist has been put forth and none can
be suggested for the Skykomish Basin. It comprises extremely
metamorphosed and crumpled rocks generally derived from sedi-
ments. This structural condition of the rocks precludes any esti-
mate as to their original thickness, but does enable one to infer
that they are of considerably greater age than any other Paleozoic
division which is much less dynamically disturbed.
MALONEY
The Maloney comprises a series of metamorphosed rocks
including quartzites, limestones, and schists of sedimentary origin
cut by basic igneous rocks, usually best described as greenstones,
which are later in age than the Maloney, but which on the evidence
of their extreme metamorphism are considered to be also of Paleo-
zoic age. The name Maloney is applied to a series formerly believed .
to be equivalent to the Peshastin series, which is called Carbonif-
erous in age. The evidence on which this correlation is made is
presented in an earlier paper. Subsequent identification of fossils
found in the limestone lenses shows the formation to be Ordovician
in age, and therefore the name Maloney is suggested.
* Warren S. Smith, ‘“‘ Petrology and Economic Geology of the Skykomish Basin,
Washington,” School of Mines Quarterly, XXXVI (1915), 157. .
STRATIGRAPHY OF THE SKYKOMISH BASIN 563
Miss Caroline A. Duror, in another part of this paper, has
identified the following fossils as of Ordovician age: Rafinesquina
deltoidea and Illaenus americanus. ‘This is the first recorded evi-
dence of the presence of Ordovician strata in the Cascade Moun-
tains of Washington, and both fossils are the first of their kind of
Paleozoic age to be found there. With this Ordovician series
begins the definitely known geologic history of the Skykomish
Basin. It was a period during which the area stood approximately
at sea-level, as evidenced by the fact that the limestone lenses
carry marine fossils. The presence of quartzite shows that prob-
ably the area was not deeply submerged, but more probably was
near the continental margin. There is no record of the post-
Ordovician Paleozoic.
MESOZOIC
There are no Mesozoic deposits at present, though there is
evidence that they must have existed. The sole known event of
the Mesozoic in the Skykomish Basin is the intrusion of batho-
lithic igneous rocks whose structural relations identify them as
Mesozoic, though there is no other positive evidence of their age.
But it is altogether probable that the batholiths were intruded as
a part of the great Sierra Nevada intrusion identified in California
and Oregon as of Jurassic age. Daly, Smith and Calkins, Russell,
Weaver, and others assert this probability. The granodiorite of
which this batholith is composed is granitoid in texture, and such
a texture can be established only under a thick cover of super-
jacent rock. This cover was removed in post-Jurassic time, leaving
the batholith uncovered at the end of the Mesozoic. Russell* and
Smith? have described sedimentary rocks of Cretaceous age, from
Whatcom County to the north, and it is therefore inferred that
removal of the 2,000 feet or more of the cover of the Jurassic
batholith was toward the north. The series, as described by Smith,
under the name Pasayten, begins with a conglomerate in which
tT. C. Russell, ‘“‘Cascade Mountains in Washington,” 20th Ann. Rept. U.S.G.S.,
Part II (1898), p. 114; G. M. Dawson, “‘ Geological Record of the Rocky Mountains
in Canada,” Bull. Geol. Soc. Am., XII (1901), 84.
2Smith and Calkins, ‘‘Cascade Mountains in Washington,” 20th Ann. Rept.
U.S.G.S., Part II (1898), p. 114.
504 WARREN S. SMITH
granitic bowlders predominate, is 6,000 feet or more thick, and is
dynamically disturbed. The Mesozoic closed with a period of se-
vere orogenic disturbance, as evidenced by the structural relations
Fic. 1.—Swauk arkose series. Conglomeratic facies
of Tertiary rocks. This unconformity is very marked, because the
earliest Tertiary sedimentaries lie at distinct angular unconformity
on the pre-Tertiary rocks, a break which is well described by
Smith and Calkins in the Snoqualmie area.t. The pre-Tertiary
*G. QO. Smith and F. C. Calkins, Folio U.S.G.S., 1906, 2.
STRATIGRAPHY OF THE SKYKOMISH BASIN 565
disturbance left the area adjacent to the Skykomish Basin on the
east in a condition sufficiently elevated to make the earliest Tertiary
a period of erosion.
III. TERTIARY
EOCENE
In the Skykomish area the Eocene was a period of sedimenta-
tion during which 4,000 feet of arkoses, shales, and conglomerates
were deposited. About the middle of the series there are two shale
formations which yield a considerable flora. The series is directly
continuous with the Swauk series of the Snoqualmie quadrangle,
and is also related to it on paleontologic grounds. It outcrops in a
belt several miles in width, striking approximately N. 45° W. in
the Eagle Creek-Beckler and the Foss River valleys. The dips
vary; in the measured section, half a mile south of the Great
Northern Railway, the base of the series lies nearly level, with
increasing dip to the east as one goes east, and to the west as one
goes west, until the top of the series stands vertical. It is an
anticline whose basal beds rest unconformably on Easton schist,
and whose roof is a part of the Keechelus andesite series.
Miss Duror’s appended report is made on the flora collected
from two horizons about 600 feet apart vertically, the lower being
1,100 feet from the base of the Swauk. Fossils numbered F 831,
F 831-++50, and F 844 are from the upper beds; those numbered
F 865 from the lower. With the latter is associated a coal bed
some 14 inches thick on which slopes have been driven in the hope
of finding minable coal.
The sandstones and Pee incrdtes are cross-bedded and the
fragments usually angular and never assorted (Fig. 1). It has
been considered a fresh-water lake deposit. In the light of the
recent developments of stratigraphy it may better be classed as
in part purely continental and in part deposited by streams, prob-
ably in deltas. The shales, and particularly those carrying complete
specimens of Sabal, could only have been laid down in situ and
must have been formed in shallow water—probably in a swamp.
None of the series bears evidence of deposition in deep water, and
both the angular condition and the considerable size of the frag-
ments forbid their having been transported for any great distance.
566 WARREN S. SMITH
Correlation.—Knowlton has done the paleontologic work on the
continental Eocene of Washington. He has made the determina-
tions both for the Eocene (Puget) of western Washington and for
the Eocene (Swauk, Teanaway, and Roslyn) of eastern Washington.
Continual reference is therefore made to him as an authority.
The original report on the Swauk' showed 25 species belonging
to the following genera: Lygodium, Sabal, Myrica, Comptonia,
Populus, Quercus, Ficus, Cinnamomum, Prunus, Diospyros, Zisy-
phus, Celastrinites, Phyllites. Of these genera, Sabal, Populus,
and Ficus are reported by Miss Duror from the Skykomish Basin,
and both Sabai and Ficus are index fossils of the lower Eocene
(Puget), as stated by Knowlton: “The following genera have been
found in the lower beds but not at all in the upper: Cladophlebis,
Lastrea, Siphonites, Ficus, Eucalyptus, and Aralia.’? Turning to
the western area we find that the Puget formation consists of some
10,000 feet of arkoses and intercalated carboniferous shales repre-
senting the Eocene. Besides the above named, Knowlton describes
Quercus, Juglans, Rhamus, Populus, and. Laurus from that series.
Of these Miss Duror reports Juglans, Populus, and Laurus, and
the presence of Ficus and Sabal correlates the Swauk with the
lower Puget (Carbonado). Miss Duror’s report further proves
the equivalency in age of the Swauk with the Fort Union of Mon-
tana, North Dakota, and Wyoming.2 The Swauk sedimentary
series may then be correlated with the lower Puget of western
Washington, with the Swauk (lowermost Eocene) of eastern Wash-
inton, and with the Fort Union areas farther east.
MIOCENE
Keechelus—This series of rocks of volcanic origin comprises
tuffs, sheets, and dikes usually of andesitic but less frequently of
dacitic composition. The tuffs predominate strongly and form
beds of unknown but considerable thickness widely distributed in
the Skykomish Basin. They overlie the Swauk sandstone, and the
t Folio 106, U.S.G.S., 1904, p. 5.
2 Folio 54, U.S.G.S., 1899, p. 3.
3 A. G. Leonard, ‘‘ Cretaceous and Tertiary Formations,” Jour. Geol., XTX (1911),
541-43.
STRATIGRAPHY OF THE SKYKOMISH BASIN 567
dikes have baked the sandstones. The Keechelus is therefore
post-Swauk in age. Contrariwise, the Keechelus series has been
indurated and otherwise metamorphosed by the Snoqualmie
batholith to the southward; in the Snoqualmie area the Keechelus
series is underlaid by a sedimentary series of sandstones and water-
laid pyroclastics (Ellensburg) which contains flora called Upper
Miocene by Knowlton. The Keechelus series in the Skykomish
Basin, being really continuous and lithologically identical with
the series of the southern area, is therefore considered Miocene
in age. As has been pointed out by Smith and Calkins, a striking
chemical similarity exists between the Keechelus andesite and the
subjacent body of granodiorite. Both fall into the same chemical
classification—tonalose. It is immediately inferred that the two
rocks are consanguineous, or, in other words, that the andesitic
pyroclastics were blown out from a magma that later solidified as
the Snoqualmie granodiorite. We must assume 2,000 feet or more
of cover, and it is suggested that this Keechelus series may very
well have provided at least a part of the cover which has later
been removed by processes of erosion. No estimate can be
made of the thickness of the Keechelus series. It is undoubtedly
widely variable and probably had a thickness of several thousand
feet. \
Snoqualmie granodiorite—Into the Keechelus series was in-
truded one of the younger of the known great batholithic intrusions.
It has a known length of major axis of about thirty miles and is
approximately two-thirds as broad. Throughout, this terrane is a
massive, fresh, granitoid igneous rock which has been discovered
by erosion to a vertical depth of 5,000 feet or more. It has, as was
seen above, metamorphosed rocks of late Miocene age, and has
sent apophyses into them, and therefore must itself be Miocene or
later in age. To account for its holocrystalline nature and for the
fact that it has been peneplaned, uplifted, and maturely dissected,
it seems necessary to put the date of its intrusion as near that of
the Keechelus as possible. The age is therefore given as late
1G. O. Smith and W. C. Mendenhall, ‘‘Tertiary Granite in Northern Cascades,”
Bull. Geol. Soc. Am., XI (1900), 224; G. O. Smith and F. C. Calkins, Folio 139, U.S.
G.S., 1906, p. 8.
568 WARREN S. SMITH
Miocene, in accordance with Smith’s interpretation.t The only
metamorphic effects experienced by this rock are the slight clouding
of feldspars and the formation of a system of joints. There is a
southernmost corner of another batholith, or, more likely, of a
subjacently connected continuation of the same batholith, north
of Grotto, and it is probable that these Tertiary batholiths form
the core of the Cascade Range throughout the northern half of
the state. Daly has correlated several of his batholiths with the
Snoqualmie batholith.
PLIOCENE
There is no stratigraphic evidence of Pliocene history. It is
physiographic rather. We infer that the Snoqualmie batholith
had a cover in excess of 2,000 feet in thickness. This Cover was
removed and the entire area reduced to one of low relief in late
Miocene and post-Miocene time. In the Pliocene the area was
uplifted with a broad arch of north-south trend and with certain
minor warpings of transverse trend. Subsequent to this uplift,
but still in the Pliocene, the area was maturely dissected by steam
action. This process of peneplanation, uplift, and mature dissection
is evidence of the very considerable duration of the Pliocene.
PLEISTOCENE
This is the age of glacial occupancy, when glaciers of the alpine
type filled the valleys to a depth of several thousand feet and
flowed down to their confluence with the Piedmont glacier of
Puget Sound. Evidence has been put forward by many writers of
two periods of glacial advance in the Puget Sound Basin, but
of course the last alpine glacier to occupy the valley would have
destroyed all evidence of any previous glaciation, and it can only
be said that the Skykomish Basin was maturely dissected by
glaciers of the alpine type in Pleistocene time. Comparatively
little time has elapsed since the glaciers withdrew from the valley.
The only stratigraphic evidence of this period is the accumulation
to a depth of several inches of a volcanic ash which has only a
1G. O. Smith and W. C. Mendenhall, ‘‘Tertiary Granite in the Northern Cas-
cades,”’ Bull. Geol. Soc. Am., II (1900), 201-28.
STRATIGRAPHY OF THE SKYKOMISH BASIN 569
slight soil covering at present—an evidence of recent volcanic
activity in the near-by volcanic cones.
RESUME
Eocene time witnessed the accumulation of 4,000 feet of arkose
sandstone. This was orogenically disturbed so that it now dips
at considerable angles. In the Miocene a series of volcanic tuffs
and andesitic intrusives were derived from a magma which ap-
proached the surface and cooled as a batholith in late Miocene.
Pliocene saw the formation, uplift, and mature dissection of a
peneplane. The Pleistocene was a period of glaciation lasting
nearly to the present, in which the Skykomish area was maturely
dissected by ice erosion.
IV. STRUCTURE
A glance at the map shows the tendency of all formations to
trend north-south. Only the Swauk arkose series deviates from
this tendency, and even this formation tends to assume a normal
relation in its northward outcrop. The great igneous terrane
(Miocene batholith) has its major axial trend in a direction parallel
to the north-south axial trend of the Cascade Range.
JOINTING
There are two known systems of joints of considerable impor-
tance and one or more of less prominence. The first two strike
N. 45° E. and N. 70° E., respectively, and the lesser system strikes
N. 80° W. It is suggested that these joints are the result of pres-
sure exerted by orogenic forces in raising the Cascade peneplane
to its present position. If this pressure were exerted continuously
in an east-west line from the Pacific side, we should anticipate a
set of joints striking N. 45° E. and a lesser set striking N. 45° W.
At least one important set of joints does strike N. 45° W. in the
Cleopatra Mine. But it is necessary to postulate a change in the
direction of application of the force to account for the system of
joints striking N. 70° E. and N. 80° W.? It seems possible that
such a change may have taken place in the direction of application
t A. Daubrée, Géologie expérimentale (1879), pp. 316 f.
2G. F. Becker, ‘‘Finite Strain in Rocks,” Bull. Geol. Soc. Am., IV (1893), 23.
57° WARREN S. SMITH
of orogenic pressure, and this change may account for the trans-
verse warping of the surface of the peneplane which is noted else-
where. The importance of the development of these structural
relations has an important influence on ore deposition (Fig. 2).
Fic. 2.—Kimball Creek. Note jointing. Rock: granodiorite
REPORT ON THE FLORA OF THE SWAUK SERIES
The flora of the beds is of Fort Union age. The material
examined yields fifteen genera and nineteen species, of which two
are new; the other seventeen species have been recorded from
STRATIGRAPHY OF THE SKYKOMISH BASIN 571
Fort Union beds. Three ferns are represented by abundant speci-
mens of Asplenium and Pteris in the shales of F 831 and F 831-+-50.
Genus Asplenium
Asplenium magnum var. intermedium var. novum (Duror) (Fig. 3)
Knowlton: ‘Fossil Flora of Yellowstone Park,” extract, Mono. XXXII,
U.S.G.S., 1899, Part 2, p. 667; Pl. LX XIX, Figs. 8, 8a.
Heer: Flora Foss. Arct., Vol. IV, ‘“‘Ostsibriens,” Taf. XX (A. whitbiense).
This form is so named because it is intermediate in character
between A. magnum (Knowlton) and A. whitbiense (Heer). The
frond is not pinnate, but the lobes are cleft one-half to one-third
of the distance to the rachis. The margin of the lobes is entire.
These lobes are one and one-half to twice as long (along midvein)
as broad and come to a rounded point.
Secondary veins come off at an angle of
about 45°, members of each pair being
almost opposite. Each secondary bears
eight to ten pairs of tertiaries, which are
generally once forked. A few rare cases of
simple secondaries and still fewer twice-
forked secondaries were observed. The Fic. 3.—Asplenium
variety differs from A. magnum of Knowlton ™agnum var. inter -
in possessing almost deltoid instead of ovate Tea Nea ae
i i ; (4 natural size.)
lobes and in being rather larger. This form
is separated from A. whitbiense of Heer, because here most second-
aries fork once only, and because Heer’s form has true pinnules—
the form being bipinnate. There is no sug-
gestion that this form is fully even once
pinnate.
GENUS Pteris
eee ae Pieris pennaeformis (Heer) (Fig. 4)
formis. (4 natural size.) O. Heer: Fl. Pert. Helvetiae (1855), p. 38; Taf. XI,
Fig. ra—d; Miocene age.
Lesquereux: Tert. Flora (1878), Pp. 523 Pl. IV, Figs. 3, 4, Pseudopennae-
formis, Lower Lignitic age.
The Cascade specimens are quite similar to that figured by
Heer, except that here only that part of the pinnae with entire
572 WARREN S. SMITH
margins is seen. Secondary veins are seen to fork twice, as in
Heer’s Fig. re, though from his description he found such nervation
EALe:
GENUS Sabal
Sabal powelli (Newb.)
Newberry: Proc. U.S. Nat. Mus., V (March 21, 1883), 504.
Later Extinct Floras of North America, p. 30; Pl. LXIII, Fig. 6; Pl. LXIV,
Figs. 1-19; Tertiary (Green River group) age of Wyoming.
Palms are represented in these beds, chiefly in F 831-++50 and in
F 865, by numerous perfectly preserved specimens of this type. In
some cases both upper and lower surfaces of the petiole of one leaf
were preserved. The forms agree in all respects with Newberry’s
type.
GYMNOSPERMAE
Gymnospermae are represented by countless fragments of
Glyptostrobus, Sequoia, and Taxodium-—this last in greatest abun-
dance. The greatest number of these
forms is found in the shales of F 831++50.
GENUS Gly ptostrobus
Gly ptostrobus ungeri (Heer)
Heer: Flora Tert. Helvetiae, 1, 51; Taf. XIX, XX,
Fig. 1; Taf. XLIX, Fig. 50. Newberry: (G.
Europaens Brogn.): 1. Annals N.Y. Nat. Hist.,
IX (1868), 43.
2. Illus. Cret. and Tert. Plants (1808), Pl. XI,
Figs. 6-8a.
3. Later Extinct Floras of N.Am., p. 24;
Pl. XXVI, Figs. 6-8a; Pl. LXV, Figs. 3-4.
Fic. 5.—A, Sequozva
nordenskioldii; cone in cross-
section (natural size). B,
Asplenium cascadia. C,Tax- = ° :
Re ceag Shaka a: No cones of this species were found,
odium distichum miocenum.
(3 natural size.) but the general form of these fragments
is like the Figs. 1e and 1a of Taf. XX,
and of Fig. 50 of Taf. XLIX of Heer. They also resemble
quite closely those from Birch Bay, Washington, figured by
Newberry (see 3 above) on Plate LV. Those were of Fort Union
age.
573
STRATIGRAPHY OF THE SKYKOMISH BASIN
GENUS Taxodium
Taxodium distichum Miocenum (Heer), Fig. 5,C; Fig. 7, D.
Heer: Miocene Baltische Flora (1869), p. 18; Taf. II, II, Figs. 6, 7.
Fig. 3, in part; Pl. LII, Figs. 2, 3, 4; Pl. LV, Fig. s.
Lesquereux: Tertiary Flora (1878), VII, 223; VIL, 73.
Newberry: Later Extinct Floras of N.Am., p. 22; Pl. XLVII, Fig. 6; Pl. LI,
2 natural size)
(
Fic. 6.—Laurus cascadia var. leve.
D, Taxodium
C, Sequoia nordenskioldit.
Fic. 7.—A, B, B', Laurus cascadia.
(4 natural size.)
distichum miocenum.
The form is Green-
The Cascade specimens are quite typical.
land Miocene or basal Eocene in age.
574 WARREN S. SMITH
GENUS Sequoia
Sequoia nordenskioldi (Heer) (Figs. 5, A, 7, C, 8, B)
Heer: . Flora Foss. Arct., IL (‘‘Miocene Spitzbergens,” 1870), 36; Taf. II,
Fig. 130; Taf. IV, Figs. ra, b, 4-38.
Newberry: Later Extinct Floras of N.Am., p. 20; Pl. X XVI, Fig. 4.
Sequoia nordenskioldi is represented by a few leafy branches
occurring with the Taxodium,:but
in addition by a handsome cone.
The cross-section is given in Fig. 5.
The form is referred to S. norden-
skioldi rather than to S. langsdor fii
because the leaves are very little if
at all narrowed before they join
and run down the stem. The
cone is almost identical with that
of Heer (op. cit., Taf. IV, Fig. 4a),
except that these dimensions are
FIc. 8.—A, Pterospermites whiter. 20X22 mm., not 16X13 mm., as
B, Sequoia ease EES Gy Sapin- Tear gives and that here noileaeee
dus obtusifolius. (% natural size.) )
remain on the branch. This cone
is not as elongate as in S. langsdorfit.
DICOTYLEDONS
There are no identifiable monocotyledons found in these beds.
Dicotyledons are represented by ten fairly well-preserved forms,
and by fragments of many more. The genera are: Ficus, Juglans,
Hicoria, Laurus, Magnolia, Populus, Protoficus, Pterospermites, and
Sapindus.
GENUS Ficus
Ficus ungeri (Lesq.)
Lesquereux: Supplement Ann. Rept., 1871, p. 7; Fig. 1.
Hayden Survey, VII (1878), 195; Pl. XXX, Fig. 3.
Numerous fragments in F 831+ 50 beds are referred doubtfully
to this form. The open-bowed secondaries in almost opposite
pairs and the “very entire” margin are identical. Noted from
Green River group, Middle to Upper Eocene.
STRATIGRAPHY OF THE SKYKOMISH BASIN 575
Ficus sp. ? (Knowlton)
Knowlton: Rept. on Fossil Plants Associated with Lavas of Cascade Range
(Western Oregon) (1898), p. 46; Pl. III, Fig. 1.
In shales (F 831-++50) a specimen very similar to Knowlton’s
figure, in the roundly notched margin, and the 45° angle of emer-
gence of the secondaries, was found. Here also no base or tip was
to be seen.
GENUS Hicoria
Hicoria (Carya) antiquorum (Newb., Knowlton)
Newberry: Ann. N.Y. Lyc. Nat. Hist., 1X, (April, 1868), 72.
Illust. Cret. and Tert. Plants (1878), Pl. XXIII, Figs. 1-4.
Lesquereux: Later Extinct Floras of N. Am. (1868), p. 35, Pl. XX XI, Figs. 1-4.
Tertiary Floras (1878), VII, 289; Pl. 1, Figs. 1-5; Vol. VIII, Pl. 1, Fig. 2.
Knowlton: Tertiary Plants of N.Am. (1898), p. 117.
Fossil Flora of Yellowstone Park, etc.
This form is found in the sandy F 844 beds. It is referred to
these species rather than to Juglans nigella, because the teeth are
here rounded, as in Hicoria, and the secondaries are less prominent
than in J. nigella. The leaf narrows gently toward the base and
joins the stem (midvein) by a quarter-inch long winged “‘petiole.”
The form is noted by Newberry and by Knowlton from Eocene
beds (Planatus) at the mouth of the Yellowstone River.
GENUuS Juglans
Juglans acuminata (Heer)
Heer: Flora Tert. Helvetiae, p. 88; Taf. CX XIX, Figs. 2-8.
Flora Foss. Arct., V1I, ‘“‘Groénlands,” 761; Taf. LX XV.
Knowlton: ‘Fossil Plants from Kukak Bay,” Alaskan Exp., 1V (1904), 1523
Pl. XXXIII, Fig. 3.
The form is identified from fragments only, but these are
rather numerous. The entire margin and the angle of the midrib
and secondaries are very similar in these specimens and in Heer’s
figures, but show considerable dissimilarity to Knowlton’s type,
where the angle between the midrib and secondaries is larger and
where the latter are alternately long and short and bowed. The
form, according to Heer, “is spread through the whole Tertiary
and possesses many synonyms.”
576 WARREN S. SMITH
GENus Laurus
Laurus cascadia N.Sp. (Figs. 6 and 7, A, B, B*)
This specific name is given to several excellently preserved
specimens in the shales of F 831. There is variation among the
forms, but hardly more than to permit of naming of two varieties.
The leaf is ovate lanceolate, coming to a sharp slender tip, and
slightly unsymmetrical at the obtusely pointed base. There are
six to eight pairs of strong secondaries, the members not directly
opposite, besides a rather faint pair at the base, where the mem-
bers are opposite. Secondaries come off at an angle of about 70°
or less, as in Fig. 7, and are very gently bowed. The tertiaries
show a horizontal parallel arrangement all the way across the
leaf, so that they do not join the secondaries at right angles, except
in the case of the two lower pairs. Fig. 6 shows preserved a fine
network of veins between the tertiaries. The margin of the leaf
is entire, and the ultimate veins border it in a series of loops.
About one-quarter inch of petiole was found (Fig. 6). In Fig. 6
the breadth is 38mm., the length probably 1oomm. The two
pieces figured are not parts of one leaf. In Fig. 7 the dimensions
are 3280 mm., and here A and B are two sides of the impression
of one leaf. A small form, very like Fig 6, but not drawn, was
about 18X35 mm. L. cascada resembles L. similis of Knowlton
(Rept. on Fossil Plants Associated with Lavas of Cascade Range of
Oregon, Pl. V, Figs. 1 and 4) merely in the horizontal tertiaries
and in the angle of the secondaries. Tip and base are, however,
quite different in the two forms. The base of L. perdita comes
nearest to being as blunt as that of L. cascadia.
Laurus cascadia leve var. nova (Duror) and L. cascadia (type)
differ largely, in that the former is proportionately broader and
with somewhat heavier veins.
GENuS Magnolia
Magnolia nordenskioldi (Heer)
Heer: Flora Foss. Arct., VII, ‘‘Groénlands,” 123; Taf. CVIII, Figs. 2, 3; IV.
‘‘Spitzbergens,”’ 82; Taf. LII, Fig. 1.
This reference is made doubtfully on certain fragments from
the sandstone of F 844. The size of the leaf, strength, and irregular
STRATIGRAPHY OF THE SKYKOMISH BASIN Slo
anastomosing of the secondaries of the veining are correct. The
tertiarles, arising at right angles to the secondaries and dovetailing
with the tertiaries from adjacent secondaries, are also similar to
Heer’s figures. The form is noted from the Canadian Miocene—
really Eocene.
GENuS Populus
Populus is represented by numerous more or less fragmentary
remains, in which, however, many of the characters are fortunately
plainly discernible. Three of Ward’s species are believed to be
present, besides one of Heer’s. The three forms are noted from
beds called Laramie, now considered of Fort Union age.
Populus amblyrhynca (Ward)
Ward: U.S.G.S. Bull. No. 37 (1887), 20; Pl. VI, Figs. 1-8.
Reference of the forms to this species is made with great cer-
tainty. In the Cascade form the base is somewhat flatter than in
Ward’s figure, the identification resting chiefly upon the character
of the thick tertiaries sent out from the inner side of the second
pair of secondaries. The resemblance is closest to Ward’s Figs. 2
andor PI Vir.
Populus cuneata (Newb.)
Newberry: Later Ext. Floras, pp. 31, 64.
Illus. Cret. and Tert. Plants, Pl. XIV, Figs, 1-4.
Lesquereux: Cret. and Tert. Floras, p. 225; Pl. XLVI, Fig. 5.
Dawson: ‘‘Cret. and Tert. Floras of Brit. Col. and N.W. Terr.,” Trans. Roy.
Soc. Can., Sec. IV (1882), p. 32.
Ward: U.S.G.S. Bull. No. 37 (1887), p. 19; Pl. IV, Figs. 5-8; Pl. V, Figs. 1-3.
One specimen was so called because the first pair of secondaries
here, as in the figures of P. cuneata, leave the midrib about 5 mm.
up from the attachment of the petiole.
Populus saddachi (Heer)
Heer: Flora Foss. Arct., 1, 98; Taf. VI, Figs. 1-4; II, 468; Taf. XLIII, Fig.
15a; Taf. XLIV, Fig. 6.
Flora Foss. Alaska, p. 26; Taf. Il, Fig. 5a.
Lesquereux: Mem. Mus. Comp. Zodl., VI (1878), No. 12; Pl. VIII, Figs. 1-8.
578 WARREN S. SMITH
This form is referred to this species because it is remarkable
for its larger size. Judging from a fragment, the complete leaf
was about 4X6 inches, as is that of Lesquereux in Fig. 8. There
are three pairs of secondaries, the lowest very faint, the innermost
very strong and straight. The margin is not preserved. Les-
quereux notes this form from Upper Miocene, but one of Heer’s
examples is Miocene of Spitzbergen (equal to Eocene).
Populus artica (Heer)
Heer: Flora Foss. Arct., IV, Taf. XXXII.
The Cascade form is very questionably referred to this species.
There is a single smooth, faintly veined leaf from beds F 831++50
whose base is almost cordate but otherwise agrees with P. artica,
and even similar bases are to be found in Heer’s figures.
Genus Protoficus (Saporta)
Protoficus is represented by many beautifully preserved speci-
mens from shales of F 831++50. They are apparently all of one new
species.
Protificus fossi N.Sp. (Figs. 9 and 10)
The leaf is lanceolate, broadest just at the middle; the apex
is a short, sharp point; the margin is irregularly, sharply dentate
to one-third of the way to the base, then wavy to crenulate. The
base is blunt to slightly tapering and not absolutely symmetrical,
as seen in Fig. to. The midrib is straight and moderately strong,
with seven pairs of secondaries. The members of each pair are
not strictly opposite, except above, where they are strongly bowed
outward. The nervation has a palmate aspect, since the two lowest
pairs of secondaries come off at the top of the petiole, and the rest
only above the lower half of the leaf, or even higher. Six
pairs of tertiaries arise from the second pair of secondaries and
form loops near the margin. Small nerves extend from these loops
into the teeth. All the other tertiaries are at right angles to the
midrib in parallel “ horizontal” rows. One small specimen measured
Ir cm. in length by 4.5 in breadth (Fig. 10); the type (Fig. 9)
is g cm. in width by 15 cm. in length.
STRATIGRAPHY OF THE SKYKOMISH BASIN 579
The tertiary veination is similar to that of Ficus tiliafolia and
there is also something of the same palmate look; but in Ficus
the gap to the next pair of secondaries is only one-third as exag-
gerated as here. The margin of FP. tiliafolia, moreover, is entire.
Protoficus sellert of Lesquereux (Bull. Mus. Comp. Zool., XVI,
No. 12 [1888], 50), while described as notably palmate, is more
cordate at the base and the border is merely crenulate. This leaf
is only 7X5.5 cm.
=
Ye
KD
YY
LOG:
<=
tS
i
4
=e)
y
=
Kn
y
i
<}
Wy
Fic. 9.—Protoficus fossi. (% natural Fic. 10.—Protoficus fossi. (% natural
size.) size.)
Protoficus inequalis (Newb.) (Proc. U.S. Nat. Mus. V [1882],
512) is not described as having a gap between the lower end and
upper secondaries and is notably unsymmetrical at the base. The
margin is merely undulate.
GENUS Pterospermites
Pterospermites whitet (Ward) (Fig. 8)
Ward: U.S.G.S. Bull. No. 37 (1887), p. 94; Pl. XLI, Figs. 5 and 6.
The species from the shales of F 831-++50 is in marked contrast
to the foregoing Protoficus. The identification is rather certain,
although the base and tip are wanting. The midrib is not quite
so sinuous above as it is in Ward’s figures. The form is noted
580 WARREN S. SMITH
from the Laramie of Montana, now conceded to be Fort Union
in age.
: GENUS Sapindus
Sapindus obtusifolius (Lesq.) (Fig. 8C)
Lesquereux: Hayden Surv., VII (1873), 266; Pl. XLIX, Figs. 8-11; VIII, 235;
Pl. XLVI, Figs. 5-7.
Knowlton: U.S.G.S. Bull. No. 204, p. 79.
The form is represented by numerous fragments such as are
shown in Fig.8,C. Better specimens (not figured) show the typical,
unequal base and the alternately stronger and weaker secondaries.
Similar forms are described by Knowlton from the Fort Union of
Montana and North Dakota.
The writer wishes to express her indebtedness to Dr. Arthur
Hollick of the New York Botanical Gardens for valuable help and
suggestions.
REPORT ON THE FAUNA OF THE MALONEY SERIES
Rafinesquina (Hall) deltoidea (Conrad) (Fig. 11, A, B, C, D), Leptaena del-
toidea Conrad, Am. Geol. Rept., 1838, p. 115.
Strophomena deltoidea Davidson, Foss. Brachiopoda, III (1864-71); Pl. XLII,
Figs. 1-5; Pl. XX XIX, Fig. 22.
Streptorhyncus (Strophonella) deltoidea (Hall, 1883), Sec. An. Rept. State Geol.
of New York, Pl. XLII, Figs. 1-7.
Rafinesquina deltoidea Hall, Pal. New York, VII; Part. I, p. 281; Pl. TXa,
Figs. 1-5. (Same figures as in references above.)
The Cascade specimens -are referred with slight hesitation to
Rafinesquina deltoidea, notwithstanding the fragmentary nature of
the material. There is a strong resemblance to Plectambonites
(Leptaena) sericius (Sow.) var. rhombica, as figured in Davidson’s
Fossil Brachiopoda, V, 169; Pl. XII, Figs. 4-7. However, the
remains of the muscle scars, and more especially the concentric
wrinkles, stronger near the hinge line, are characteristic of Rajfines-
quina. The alternate striation, such as the Cascade specimens
show, is described in both forms, “every fifth or seventh striation
markedly stronger.’’ Here generally every fifth striation, though
rarely every seventh, and occasionally every second, is emphasized.
Such a variation, and another in the profile of the shell, is noted
STRATIGRAPHY OF THE SKYKOMISH BASIN 581
by Professor M’Corg (quoted in Hall, op. cit.). In these specimens
the most convex shell (Fig. 11, A, B) is not sharply flexed at any
one point, while younger individuals, as in Fig. 11, C, show less
arching, but a more sudden geniculation. The specimens are partly
exfoliated and have a finely punctate surface.
Fig. 11, A, B, and D are of pedicle valves, and Fig. 11, C of a
brachial valve. This last specimen is partly an impression of the
Fic. 11.—Rafinesquina (Hall) deltoidea (Conrad). A, B, and D, pedicle valves;
C, brachial valve.
outer surface of the shell, since the striations show as grooves;
but part of the true shell remains where the muscle scars are shown.
Illaenus americanus (Billings)
Billings (1859, quoted; 1865, quoted and figure copied): Paleozoic Fossils,
i329; Fig. 216a—d.
Winchell and Ulrich: Minn. State. Surv., III (1897), Part II, 714; Figs. (from
above) 20, 21, 22, 23.
Fic. 12.—Illaenus americanus (Billings). A, front view; B, top view; C, side
view.
A single specimen, the glabella and fixed cheeks, was found
associated with the Rafinesquina deltoidea. All the features on
these parts agree perfectly with Billings’ figures. This specimen
probably belonged to an animal one inch long, while Billings’
582 WARREN S. SMITH
forms ranged from two to three inches in length. Naturally,
smaller forms have been noted, as in Grabau and Shimer, Index
Fossils, p. 295, where one and one-fourth inches is given as the
entire length.
Fig. 12, Ais the front, Fig. 12, B the top, and Fig. 12, C the side
view of the one specimen. The dotted line in Fig. 12, B gives the
outline of the eye, which was destroyed in uncovering the fossil.
Both of these forms are index fossils of Trenton age. Naturally,
they are not restricted to one bed, but in no case have they been
recorded as younger than Ordovician.
The writer is indebted to Dr. Shimer and to Dr. Grabau for
valuable help and advice.
“PUFF” CONES ON MOUNT USU
Y. OINOUYE
Imperial Tohoku University, Sapporo, Japan
Two days before the eruption of Mount Usu, in southwestern
Hokkaido, Japan, the writer arrived at the foot of the volcano.
He remained there for twelve days, watching every phenomenon,
going without sleep the first five days. The first explosion occurred
HOKKAIDO
* SAPPORO
bit ust
Fic. 1.—Sketch map of southwestern part of Hokkaido
on July 25, 1910, and others followed in rapid succession. Violent
eruptions ceased in about ten days and the writer returned to
Sapporo on August 7. He again visited the volcano in September
and in December of the same year, in May and October, 1911, in
583
584 Y. OINOUYE
May, 1912, and in May, 1913. Many interesting facts were ob-
served which will be published later in another paper. Here
attention is to be called only to certain peculiar cones formed on
one of the mud flows.
The main eruption of the volcano caused the formation of
forty-five small explosion craters on its northern slope. These
craters extend from east to west in two zones along Lake Toya,"
north of the volcano. During the first few months after their
formation innumerable bombs and considerable quantities of
sand and ashes were blown from every craterlet. From five of
them mud flowed at different times, the flow from a small crater
at the southern foot of the parasite cone Nishi-Maruyam being
especially interesting. This crater is located on a gentle slope of
about five degrees, and is 100 meters in diameter. For twenty
days it intermittently threw out columns of hot water, occasionally
mingled with mud, to a height of about 60 meters. Approximately
two hundred eruptions occurred per day at intervals of from three
to thirty minutes. A mass of mud, estimated by the writer at
230,000 cubic meters, spread out in a sheet averaging 1.5 meters
in thickness, over an area 200 by 700 meters. It covered a farm,
where it destroyed a thousand apple trees and other crops, and
pushed three houses in the direction of the lake and finally
destroyed them.
The mud consists mainly of plagioclase, hypersthene, augite,
magnetite, and hematite, and resembles the material of the sea
sand at the west foot of Mount Usu. It differs, however, in also
containing fragments, from the size of peas to that of nuts, of com-
pact gray to coarse black andesite. These fragments are not usually
exposed at the surface of the mud, having sunk on account of their
greater size. :
The materials thrown out by the crater were highly heated and
sticky at the time of their eruption, and contained a great amount
of water and gas. For several months the flow continued steaming,
but as time passed and the moisture and gases became exhausted,
it ceased, and the mass became harder and harder. A year after
* Lake Toya is a depression lake, according to T. Kato (Report Earthquake Investi-
gation Committee, Vol. LXII).
“PUFF” CONES ON MOUNT USU 585
the eruption the surface of the flow was so hard that it was difficult
to discern footprints upon it, and specimens could be obtained
only with the aid of a pointed stick ora hammer. At this time the
surface was flat except for low, wavy undulations and very irregular
sun cracks.
A year later the writer found the flow covered with thousands
of small cones, each of which had an opening which was compara-
BAY
of
VoLCANO
Crater lets
5
Mud flow
Fic. 2.—Map of Mt. Usu and vicinity, showing the position of craterlets and mud
flow here described.
tively large but of no particular shape. The cones were of different
sizes, the smallest being 0.5 meter in diameter and o.1 meter
in height while the largest was 3.0 meters in diameter and 1.5
meters in height. They were irregularly arranged on the flow
at intervals of to to 30 meters, and were either dome-shaped or
resembled a common bell with a slope of forty degrees.
The cause which produced these elevations is the same as that
which forms small pitted cones when any viscous substance is
boiled, namely, the escape of gases or vapors through the mass
586 VY. OINOUVE
and the breaking of the bubble at the surface. After the cessation
of the mud flow the surface dried and sun cracks were formed.
The gases near the surface rapidly escaped through these openings,
but those imprisoned near the bottom of the mass were unable to
do so, the upper part only having dried out. Later, by the coales-
cing of the small bubbles, the remaining gases united beneath the
surface in reservoirs of greater size. The accumulated pressure
finally became great enough to force a passage through the mud to
the surface, the sudden escape of the gas forcing the mud upward
Fic. 3.—The largest “puff”? cone. Photo taken by the writer, May 16, 1912
to form cones. ‘The other mud flows in this district, being thinner,
dried out more rapidly, and no cones were formed.
The writer has been unable to find descriptions of any such
phenomenon in the case of other mud flows, although similar
elevations occasionally occur on lava flows. He therefore suggests
the name ‘“‘puff cones.”’
No new cones were formed after the summer of 1912, the greater
part of the gas having been expelled. Since that time weathering
has begun to reduce the slopes, so that, in all probability, no trace
of this fantastic phenomenon will remain after a few years.
ORIGIN OF FOLIATION IN THE PRE-CAMBRIAN ROCKS
OF NORTHERN NEW YORK?
WILLIAM J. MILLER
Northampton, Massachusetts
INTRODUCTION
Data bearing upon the problem of the origin of foliation in the
pre-Cambrian rocks of northern New York have been gathered dur-
ing the last ten years by the writer while he was engaged in the
geological surveys of various quadrangles in the Adirondack
Mountain region. In the attempt to explain the origin of the
foliated structures of the rocks, examples and analogies from other
parts of the world will be introduced, and it is hoped that the con-
clusions reached may have a wider application than to the Adiron-
dack region alone.
This paper is not much concerned with criteria for the deter-
mination of original igneous or sedimentary character of the rocks.
The conclusions reached are almost wholly based upon observations
made upon rocks which have been generally recognized as quite
certainly either igneous or sedimentary. Rocks of rather doubtful
origin are frequently met in minor quantity, but these may be
disregarded in the present discussion.
The strata all belong to the very ancient Grenville series, includ-
ing various gneisses and schists, together with crystalline limestone
and quartzite. The chief criteria for the determination of their
sedimentary origin are: distinct banded structures, often showing
alternating layers of widely different composition sharply separated
from each other; presence of extensive bodies of limestone and
quartzite interbedded with the gneisses; dissemination of graphite
flakes through many of the rocks; and the very common occurrence
of garnet in many of the rocks, and the less common occurrence
of sillimanite.
t Published by permission of the Director of the New York State Museum.
587
588 WILLIAM J. MILLER
The metamorphic rocks of igneous origin, given in regular order
of geologic age, comprisé the anorthosite series, the syenite-granite
series, and the gabbros, all of which show quite varied degrees of
metamorphism. All are intrusive rocks and younger than the
Grenville. Among the criteria for recognizing their igneous origin
are: preservation of original rock textures, such as the porphyritic
and the diabasic; relative homogeneity in large bodies; common
occurrence of distinct inclusions of older rocks; intrusive contacts,
often with dikes from the large bodies penetrating the older rocks;
very common occurrence of zircon and zoisite in fresh, well-
crystallized grains.
THE GRENVILLE AND ITS FOLIATION
FOLDING OF THE GRENVILLE
Character of the Grenville series —The Grenville series comprises
the oldest rocks of the Adirondack region, and they: are, in fact,
among the most ancient known rocks of the earth’s crust. They
consist of a great mass of thoroughly crystallized sediments, such
as limestones, sandstones, and shales which have been changed to
crystalline limestones, quartzites, and various gneisses and schists.
A more or less well-developed foliation is always parallel to the
stratification surfaces which are usually distinctly preserved in
spite of the crystallization. Granulation is not common. Gren-
ville strata are well represented throughout the Adirondack region,
their distribution being very irregular or ‘‘patchy”’ in small to large
areas. They are considerably less extensive than the later (intru-
sive) syenite-granite series, which latter, together with the Gren-
ville, makes up the great bulk of Adirondack rocks. Neither top
nor bottom of the Grenville series is known, though thicknesses
of from 10,000 to 20,000 feet are actually shown in single sections,
and the total thickness is doubtless much greater. Adams and
Barlow report a Grenville section about eighteen miles thick in
Ontario. The strata are often tilted at high angles or very moder-
ately folded, and sometimes locally contorted. There is a general
tendency toward a northeast-southwest strike of Grenville masses
in the Adirondacks, but there are many important exceptions.
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 589
Grenville series generally regarded as highly folded and com-
pressed.—It has been quite generally assumed by all (including the
writer) who have carried on geological work in the Adirondack
region that the Grenville strata have been severely compressed and
folded as well as thoroughly metamorphosed and foliated by the
compression. A few citations from the more recent publications
will illustrate the ideas usually held. “There is abundant proof
that the rocks have undergone great compression and have been
folded and faulted on an extensive scale.”* The Grenville rocks
“have been greatly compressed and intricately folded and pli-
cated.’ ‘The old sedimentary rocks have undergone complete
recrystallization, entirely obliterating their old textures, and, as
a result of severe compression, have had a development of cleavable
minerals along certain parallel planes, the mineral particles having
a common orientation.’’3 ‘In pre-Potsdam time the pre-Cambric
sediments had been tremendously folded and faulted and intruded
at great depths.’* “After the intrusions the whole region was sub-
jected to intense compression and metamorphism when the gneissic
or foliated structure of all the rocks was developed.’’s
An alternative hypothesis—That the Adirondack Grenville
strata are more or less folded is admitted at the outset, but, in the
light of recent studies, the writer doubts the interpretation of the
folded, tilted, and foliated structures as due to intense lateral
compression. Certain evident features of the Grenville strata and
related intrusives are directly opposed to this interpretation, while
all of the structural features may be much more satisfactorily
explained in another way. Thus it is conceived that the originally
horizontal, or at most only very moderately folded, Grenville strata
were much broken up and tilted in masses great and small, and in
other cases actually domed, by the irregular upwelling of the great
bodies of magma (especially syenite-granite) under only very
moderate lateral pressure. This alternative explanation will be
1D. H. Newland, New Vork State Mus. Bull., No. 111, 1908, p. 20.
2H. P. Cushing, zbid., No. 145, 1910, p. 9.
3 Ibid., No. 95, 1905, p. 400.
41. H. Ogilvie, 2b¢d., No. 96, 1905, p. 478.
5 W. J. Miller, zbzd., No. 170, 1914, p. 77.
590 WILLIAM J. MILLER
developed at some length in its application to the Adirondack
region.
Evidence against intense folding of the Grenville——In spite of the
assumption of severe lateral compression, no large-scale example
of intense folding of the Grenville has ever been positively demon-
strated in the Adirondacks, and this in the face of the fact that many
hundreds of square miles have been mapped in detail. Describing
the Grenville structures of the Elizabethtown—Port Henry quad-
rangles, Kemp says: ‘The dips are prevailingly moderate and the
ancient sediments appear to have been folded or tilted to only a
moderate degree.”* Regarding the Long Lake quadrangle, Cushing
says: ‘Nearly east and west strikes prevail, and the prevalent
dip is southward. This either indicates comparatively little fold-
ing, or else isoclinal folding, or else that the foliation does not
coincide with the bedding and so does not bring out the folding.
It is not possible to demonstrate which of these alternatives is the
true one, though the second is very unlikely, and all the direct
evidence obtainable is against the third.’ He also states that in
the largest Grenville belt ‘the dips are so flat that they can seldom
be made out with certainty.”
The writer’ has described a structure section in the Broadalbin
quadrangle four miles long across the strike of Grenville strata
with dips of 20-30° to the southeast. The. exposed thickness of
Grenville is about 10,000 feet with no repetition of beds due to
possible isoclinal folding and no field evidence for profound faulting.
Another Grenville section recently described by the writer? in the
North Creek quadrangle is five miles long with a pretty uniform
dip of from 40° to 50°, thus showing a thickness of some 18,000-
20,000 feet of strata. There is no evidence of repetition of strata
by either folding or faulting. The Grenville is extensively devel-
oped throughout this quadrangle, and all the available evidence
points to only moderate deformation of the strata either by tilting
or slight folding.
tJ. F. Kemp, New York State Mus. Bull., No. 138, 1910, p. 85.
2H. P. Cushing, zbid., No. 115, 1907, p. 485.
3 W. J. Miller, zbzd., No. 153, roti, p. 13.
4 Ibid., No. 170, 1914, p. 15.
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 5091
According to Cushing, “the foliation strike over much of the
Saratoga quadrangle is nearly east-west, and the dips are to the
south and rather flat, seldom reaching 45°. As elsewhere, a great
monocline of the rocks is suggested, and, as elsewhere, this makes
a Grenville succession of enormous thickness, so thick as to suggest
caution in the interpretation of the structure, and as to emphasize
the probability of the alternative suggestion that the rocks are
closely pinched and folded in a series of closed, overturned folds.’
It is, however, by no means necessary to assume that such common
occurrences of monoclinal dips may be due to isoclinal folding.
The breaking up and tilting of many blocks or belts of Grenville
strata into general parallelism with the upwelling bodies of magma
could quite conceivably have taken place under only very moderate
lateral compression at most, and, in such cases, monoclinal dips
are Just what would be expected. This matter will be more fully
discussed below.
In the Little Falls, Remsen, Port Leyden, and Lake Pleasant
quadrangles, which are also mapped in detail, the Grenville is
only sparingly represented, but none of the field evidence points to
profound folding of the strata due to lateral compression.
The recent (1913-14) survey of the Blue Mountain quadrangle
by the writer has thrown important light on the structure of the
Grenville series which is there extensively represented. The
great Panther-Snowy mountain mass (altitude 3,900 feet) of syenite
occupying the southern portion of the Blue Mountain and the
northern portion of the Indian Lake quadrangles is completely
bounded on the west, north, and northeast by an unbroken belt
of Grenville (mostly limestone) whose strikes and dips show it to
lap up on the flanks of the mountain mass of igneous rock for many
miles. The curving strike of the igneous rock is also essentially
parallel to that of the Grenville. It is evident that we have here a
large-scale example of the raising or doming of Grenville over the
surface of the great body of uprising magma, the general cover
having been removed by erosion, leaving only the circumferential
belt of Grenville strata. The higher portions of the syenite now
rise fully 2,000 feet above the Grenville. This large-scale tilting
tH. P. Cushing, zbid., No. 169, 1914, p. 30.
592 WILLIAM J. MILLER
of Grenville strata is certainly not due to severe lateral compression,
nor is there, in any part of the quadrangle, evidence of highly folded
or compressed Grenville strata.
In the northwestern part of the Thirteenth Lake quadrangle
the writer has examined Chimney Mountain, which is a mass of
granitic syenite rising fully goo feet above a valley on the west.
Perfectly bedded Grenville rocks with dip of 50° lap over the whole
western face of the mountain of igneous rock, and it seems certain
that the tilt of the strata was produced by the rise of the magma.
We are thus led to conclude that none of the published Adiron-
dack geologic maps or available data afford any reason to believe
that the Grenville strata were ever profoundly folded or compressed.
There is, however, much tilting on large and small scales and some
very moderate folding. Such structures may be readily accounted
for simply by the irregular intrusion or upwelling of great bodies
of more or less plastic magma which broke up, tilted, and lifted or
domed the masses of Grenville.
Grenville structure in the Thousand Islands and Ontario regions.—
The Thousand Islands district forms the connecting link between
the Adirondack and Canadian pre-Cambrian areas, and lies to one
side of the region discussed in this paper. Having recently studied
_the Thousand Islands district, Cushing says: ‘The Grenville
beds are now found for most part in highly inclined condition, dips
of less than 45° being relatively rare, while those approaching
verticality are common. . . . . It has also been shown that
the dip is not everywhere in the same direction, but that, with the
general direction of strike to the northeast-southwest, the dip,
while prevalently to the northwest, becomes at times southeast.
. The highly tilted condition of the rock series, and the
changing dips seem certainly indicative of folding.’ He then
describes a prominent belt of Grenville strata which he believes
has a synclinal structure. But, accepting the existence of this
syncline, does such a structure prove the region to have been sub-
jected to an intense force of compression? Large bodies of granite
bound this Grenville belt on either side, and it is quite conceivable
that the uplifting effect of the intruding masses, possibly accom-
*H. P. Cushing, New York State Mus. Bull., No. 145, 1910, Pp. 109.
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 593
panied by some crowding or squeezing of the Grenville between the
igneous masses, may have produced this very structure. Cushing
also argues that “the general parallelism of the foliation of all the
pre-Cambric rocks” affords “evidence of thoroughgoing compres-
sion of much later date” than the granitic intrusions. But, as will
be shown below, such parallelism of foliation is not necessarily
due to severe lateral compression. It should be said, however,
that in the Thousand Islands region the granitic and Grenville
rocks do seem to be more strikingly arranged in parallel northeast-
southwest belts than is usual throughout the Adirondacks. It is
possible that considerable orogenic forces did operate across the
area from the Thousand Islands region northward into Canada,
where also the parallelism is notable. Recent study of the Canton
quadrangle seems to indicate considerable folding there. Adams
and Barlow, in their description of the Haliburton and Bancroft
areas, state that the batholiths ‘“‘are elongated or arranged in lines
having a prevailing direction of about N. 30° E., to which direction
the strike of the rocks (Grenville) lying between the batholiths in
general conforms. This direction constitutes, so to speak, the
general strike of the country, and shows that its present structure
has been determined, not only by the rise of granite magma, but
by the presence of a second factor in the form of a tangential
pressure, acting simultaneously.”* But it is not at all certain
that this tangential pressure was really orogenic in character.
Even a very moderate compressive force, not at all sufficient
thoroughly to fold and plicate the rocks, acting upon the rising
magmas would readily account for all the structural phenomena
now visible.
Variation of foliation strikes.—Even if we grant a very consider-
able lateral compression in the Thousand Islands—Canadian region,
the Adirondack area, fully a hundred miles across and to the south-
east, does not necessarily come under the same category. In fact,
while parallelism of syenite-granite and Grenville rock belts and
foliation are common in the Adirondacks, there are so many
important variations from a northeast-southwest strike that any
generalization regarding such a strike of the rock belts is of little
t Adams and Barlow, Geol. Surv. Can., Mem. 6, 1910, p. 16.
594 WILLIAM J. MILLER
significance. A glance at the accompanying sketch map (Fig. 1)
will emphasize the fact that various large areas show strikes dis-
tinctly out of harmony with a northeast-southwest structure.
The unpublished Lake Placid geologic map shows exceedingly
variable strikes. Many variations also occur within most of the
other quadrangles, more especially the North Creek, Long Lake,
and Blue Mountain (unpublished). Within the Lake Pleasant
quadrangle, the foliation strikes relatively uniformly northwest-
Fic. 1.—Sketch map of the Adirondack region showing generalized strikes of
foliation within those quadrangles which have been mapped in detail.
southeast or just at right angles to the assumed force of compres-
sion of the region. Papers by Professor Kemp and assistants in
the thirteenth, fifteenth, seventeenth, eighteenth, and nineteenth
annual reports of the New York state geologist contain many very
variable strike observations in the eastern Adirondacks aside from
the quadrangles of the accompanying sketch map. It thus seems
clear that the Adirondack rocks show strikes which could not pos-
sibly have been produced by a severe lateral pressure exerted across
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 595
the whole region, for any such pressure, great enough to produce
close folding, would have produced a high degree of parallelism
of strikes throughout the region.
Local contortions.—Local contortions or sharp folds in the Gren-
ville strata are by no means uncommon, being especially prominent
in the limestones and closely associated hornblende and pyroxene
gneisses. Such plications have usually been regarded as strong
evidence for large-scale folding, being thought of as minor folds
superimposed upon large-scale folds. Now, in the first place, it is
the writer’s experience that such local contortions or plications are
very largely confined to the limestone beds, which are easily the
most plastic of all Adirondack rocks. In the second place, the
crowding of a batholithic magma against the invaded Grenville
strata, or the catching of a mass of Grenville between two batho-
lithic magmas, would readily account for more or less local contor-
tions or even puckering of strata without any assumption of orogenic
or severe lateral pressure exerted throughout the region. The
shouldering action of the upwelling magmas must have produced
rather severe local pressures. Regarding the Glamorgan batholith
of Ontario, Adams and Barlow say that the Grenville rocks form-
ing the periphery on several sides, “being squeezed between this
and the adjacent batholiths, are too highly contorted .... to
display the prevailing dip distinctly.”* Evidently such structures
do not necessarily call for severe regional compression.
Summary.—To summarize, there is no known evidence within
the Adirondack region that the Grenville strata have ever been
highly folded or severely compressed, while many broad Grenville
belts are known to be only very moderately folded, and many
masses, large and small, are merely tilted or domed at various
angles. Very locally the strata are sometimes contorted or plicated.
The structural relations are therefore best explained as having been
the result of slow irregular upwelling of the more or less plastic
magmas, probably under very moderate compression, whereby
the Grenville strata, previously deformed very little or none at all,
were broken up, tilted, and lifted or domed. The stratification
suriaces of the Grenville were thus swung into general parallelism
t Adams and Barlow, Geol. Surv. Can., Mem. 6, 1910, p. 15.
596 WILLIAM J. MILLER
with the slow-moving magmatic currents. According to this view, |
individual large blocks or belts of Grenville strata, or several such
blocks or belts separated by intrusive masses, with strike of intru-
sive masses parallel to Grenville stratification, would be expected
to show monoclinal dips; some Grenville masses were shifted around
in irregularly rising magmas so as to show various strikes according
to directions of movement of the magmas, and hence would not be
expected to exhibit monoclinal dips; some Grenville masses were
merely domed over bodies of rising magma and would exhibit more
or less quaquaversal strikes and dips; while still other Grenville
masses were probably bent or even considerably folded into syn-
clines by being caught between bodies of magma upwelling at about
the same rate. Isoclinal or close folding on a large scale would
scarcely be expected.
In all of this discussion it is important to bear in mind that the
Adirondack intrusives occupy a much greater extent than the
invaded Grenville rocks, and that, in spite of their intrusive char-
acter, they everywhere seem to occupy the position of a fundamental
or underlying gneiss. It appears to have been literally true that.
the Grenville strata were irregularly floated on a vast body of
magma, the magma in many places having either arched up or
broken through the strata.
ORIGIN OF GRENVILLE FOLIATION
We have just shown that the Grenville strata have never been
highly folded or compressed. It is therefore necessary to explain
the metamorphism of the strata on some other basis than that of
subjection to severe lateral pressure. The old sediments are thor-
oughly crystallized, and it is certain that they have been reorganized
into new minerals under deep-seated conditions; that is to say,
they have undergone anamorphic metamorphism. But evidently
we are here dealing with a case of essentially static, rather than
dynamic, metamorphism.
Origin of parallelism of Grenville foliation and stratification.—
The universal parallelism of Grenville foliation and stratification
is a fact of prime importance. If the Grenville and accompanying
great intrusives had been subjected to compression severe enough
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 507
to develop the distinct foliation, is it not remarkable that the strati-
fication surfaces have never been obliterated and cleavage developed
instead, and also that the stratification and foliation are always
parallel? Now, the stratification of the highly crystalline Gren-
ville is remarkably well preserved. Also, unless we assume intense
isoclinal folding, so that mineral elongation could everywhere have
taken place at right angles to the direction of lateral pressure, the
parallelism of stratification and foliation cannot be accounted for
by crystallization under severe lateral pressure. We have already
shown, not only that there is no positive evidence for such isoclinal
folding, but also that there is much positive evidence against any
more than the tilting, or, at most, very moderate folding, of the
Grenville on large scales.
Again, if the foliation of the Grenville were essentially a dynamic
-process—that is to say, the result of regional compression after the
great igneous intrusions—why should the Grenville be notably less
foliated and granulated than the intrusives? (See below.)
We are thus forced to the only alternative conclusion, namely,
that the Grenville foliation was developed during the crystalliza-
tion of essentially horizontal strata under heavy load of overlying
material. Those minerals which cause the foliation were elongated
during crystallization under heavy downward pressure where con-
ditions of warmth and moisture were also favorable. According
to this conception the parallelism of foliation and stratification is
precisely what would be expected. It is quite generally assumed
that static pressure, that is to say, simple downward pressure,
“to the amount exerted in the upper part of the earth’s outer crust,
appears to have little metamorphic effect.”* In dealing with the
very ancient Grenville, however, it must be remembered that the
material now at the surface was once very deeply buried. The
thickness of the Grenville series in the Adirondacks is at least some
miles and more than likely many miles. Adams and Barlow? have
recently estimated a thickness of nearly eighteen miles for the
Grenville strata in Ontario. It is also definitely known that during
pre-Cambrian time the Grenville strata were subjected to tre-
tL. V. Pirsson, Rocks and Rock Minerals (1909), p. 335:
2 Adams and Barlow, Geol. Surv. Can., Mem. 6, 1910, p. 33.
598 WILLIAM J. MILLER
mendous erosion when at least some miles, and quite possibly
many miles, in thickness of materials were removed. Thus it
seems clear that much of the Grenville rock now visible was once
far more deeply buried than any known body of sediments since
the beginning of the Paleozoic. Conditions of downward pressure
and temperature were, therefore, more than usually favorable for
static metamorphism. On the basis of static metamorphism it
is not necessary to account for a high degree of metamorphism,
because the Grenville series, though thoroughly crystalline, is
mostly only moderately foliated with relatively little granulation,
and with stratification generally well preserved. It may also be
suggested as a possibility that actual crystallization did not begin
until an early stage in the intrusion of the slowly upwelling magmas
when additional heat for regional metamorphism was supplied.
Evidence from other sources.—Experimental evidence is also
suggestive in this connection. Thus, Becker and Day" have proved
that crystals in general have a strong tendency to grow (or elongate)
most rapidly at right angles to the direction of pressure. According
to Wright,? cubes of glass formed by melting together wollastonite,
diopside, and anorthite heated to the state of incipient crystalliza-
tion under vertical pressure, showed, under the microscope, that
the three minerals crystallized with long axes at right angles
to the direction of pressure. Experimental evidence, therefore,
strongly supports the possible development of elongated crystals
in the Grenville sediments under conditions of static metamorphism.
Van Hise has suggested, regarding the parallelism of foliation
and bedding in the Grenville series, that ‘‘ vertical shortening and
consequently horizontal elongation below the level of no lateral
stress may have begun the process.”’ The writer views this as
essentially the whole process, instead of assuming, as Van Hise did,
that foliation parallel to bedding continued to develop under certain
peculiar conditions when the rocks were subsequently folded.
The explanation of foliation parallel to bedding is greatly simplified
when it is not necessary to consider severe compression of the region.
t Becker and Day, Proc. Wash. Acad. Sci., VII (1905), 283-88.
7F. E. Wright, Am. Jour. Sci., 4th series, XXII (1906), 226.
3C. R. Van Hise, U.S. Geol. Surv., 16th Ann. Rep., Part I, p. 773.
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 509
Describing the metamorphism of the Shuswap pre-Cambrian
series in the Canadian Rockies, Daly says: ‘It is clear that the
Shuswap series has not been seriously affected by dynamic meta-
morphism. ‘The strata and most of the injected granites were
completely or almost completely recrystallized while the strata
lay nearly flat. In some localities the effects of dynamic meta-
morphism have been superposed on those due to previous static
metamorphism.’
Orientation of Grenville inclusions.—Another fact of importance
in connection with the origin of Grenville foliation is the occasional
occurrence of well-foliated inclusions of Grenville gneisses variously
oriented in the great intrusive bodies. Twenty years ago, in St.
Lawrence County, Smyth, noting irregular inclusions of black
gneiss in granite, said: “The two foliations, that of the black masses
and of the (granite) gneiss, range from parallel with, to perpendicu-
lar to, each other.’”? He also noted a similar arrangement of
Grenville laminated gneiss inclusions in syenite in Jefferson County.
The writer has observed similar phenomena on small and large
scales at various localities. Kemp has recently noted inclusions in
massive anorthosite and says: “The foliation of the fragments runs
in all directions, even in an area of a few square yards. The infer-
ence is drawn that the Grenville gneisses were already strongly
metamorphosed when the anorthosites entered.’ It is thus clear,
in spite of the usual assumption to the contrary, that the foliation
of the Grenville could not have been the result of lateral pressure
brought to bear after, or even during, the intrusion of even the oldest
oi the great igneous masses.
General absence of granulation.—Another fact favoring a process
of essentially static metamorphism as opposed to that of dynamic
metamorphism is that the Grenville gneisses are, as a rule, com-
paratively little granulated. Some rather local granulation is
to be expected because of magmatic movements, especially where
Grenville masses have been crowded against the upwelling magmas.
The great intrusive syenite-granite series is very notably more
tR. A. Daly, Geol. Surv. Can., Transcont. Excur. C 1, Guidebook 8, 1913, p. 132.
2C. H. Smyth, 15th Ann. Rep. New York State Geologist, 1895, p. 491.
3 J. F. Kemp, Geol. Soc. Am. Bull., XXV (1914), 47.
600 WILLIAM J. MILLER
granulated than the Grenville series. How is this fact to be
explained if both series have been subjected to strong regional
compression after the intrusions ?
THE SYENITE-GRANITE SERIES AND ITS FOLIATION
Character of the syenite-granite series—The main bulk of syenites
and granites in the Adirondacks are regarded by the writer as facies
of a single great body intrusive into the Grenville, the intrusives
being much more extensively exposed than the Grenville. Perfect
gradations from basic (dioritic) facies of syenite to true granite are
commonly shown, a quartz syenite being the prevailing rock. As re-
gards granularity, structure, and mineral composition, themembers of
the syenite-granite series are very variable. The granularity ranges
from fine to coarse grain, with medium grain decidedly prevalent.
A porphyritic texture is sometimes well developed. Granulation is
common, especially in the more acidic rocks, the feldspars generally
being notably more crushed than the other minerals. In structure
the rocks range from very faintly gneissoid to very clearly gneissoid
or sometimes almost schistose, the foliation being accentuated by
the roughly parallel arrangement of the dark-colored minerals.
The minerals, especially quartz and feldspar, often show more or
less flattening or elongation parallel to the foliation. In general
the more highly foliated rocks appear to be most granulated. In
mineral composition the range is from dioritic types rich in plagi-
oclase, orthoclase, pyroxene, and hornblende; to syenite rich in
microperthite, orthoclase, and hornblende or augite together with
some quartz and plagioclase; to granite rich in microperthite,
quartz, orthoclase, and microcline together with some plagioclase,
hornblende, and biotite. Various accessory minerals in smaller
amounts also occur. The color of the typical fresh syenite is
greenish gray which weathers to light brown, while the fresh
granite colors vary from greenish gray to light gray and pinkish
gray to almost red. In common with the Grenville, the
syenite-granite foliation shows a tendency toward a northeast-
southwest strike, with parallelism of syenite-granite and adja-
cent Grenville quite common, though there are many notable
exceptions.
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 601
Northeast-southwest structure of rocks.—We have shown that the
Grenville series has never been closely folded or severely com-
pressed, and that its foliation was not caused essentially by lateral
pressure. ‘The syenite-granite masses, being younger than an
intrusive into the Grenville, cannot, therefore, have had their
foliation developed chiefly by lateral pressure, though the probable
existence of a very moderate lateral pressure is admitted.
In spite of many important exceptions, there is some tendency
toward a general parallel northeast-southwest to east-west strike
of Adirondack rock masses (Grenville and syenite-granite) and
foliation. One view, clearly stated by Cushing, is that ‘‘since the
rock [granite] solidified it has been subjected to compression, to-
gether with the Grenville rocks, giving to each a foliation parallel
to the other, and elongating the batholiths in a northeast-southwest
direction.’”* At another place he refers to this compression as
“‘thoroughgoing”’ and of much later date than the granite intrusion.
Cushing suggests the possibility of the development of ‘“‘a similar
and parallel foliation’ during the solidification of the batholiths
due to their shouldering pressure exerted upon the adjacent rocks
during the intrusion, but he says that if any such foliation de-
veloped it was obliterated by subsequent compression. |
The writer’s view is that the general northeast-southwest
structural parallelism was brought about by just enough tangential
compression to control the general directions of the upward-
moving batholithic magmas. Accordingly, the intrusive bodies
were more or less elongated during the process of intrusion, and
there must have been a strong tendency for large and small bodies
of previously horizontal, or only slightly deformed, Grenville
strata to have been caught up and arranged with their long axes
and foliation parallel to the magmatic currents, while the foliation
of the intrusives would also have developed, as a sort of flow struc-
ture under moderate pressure, parallel to the magmatic currents.
This pressure was doubtless in part due to the shouldering effect
of the intrusives upon the adjacent rocks. In other words, the
syenite-granite gneisses are ‘‘primary gneisses.” Thus we should
1H. P. Cushing, New York State Mus. Bull., No. 145, 1910, p. 10.
2 [bid., No. 145, 1910, p. 102.
602 WILLIAM J. MILLER
expect a general northeast-southwest strike of both rock masses and
foliation of Grenville and intrusives to be of common occurrence.
A statement made by Smyth twenty years ago regarding black
gneiss inclusions in the syenite-granite series of St. Lawrence
County is significant in this connection: ‘The parallel arrangement
of the neighboring bands [inclusions] doubtless results from currents
in the molten magma, which would tend to produce such a result.
It is probable that the breaking into blocks resulted, in part, from
strains applied after the magma was in a pasty and partially crystal-
lized state. The blocks were more or less widely separated, and
the intervening space was filled by the magma which flowed around
the blocks without destroying their angular contour, and, at the
same time, often produced an obscure flow structure in the gneiss
parallel to the sides of the inclusions.”' The bandlike inclusions
here described by Smyth are seldom more than a few rods long,
but the writer believes the principles set forth are applicable on a
much larger scale throughout the Adirondack region.
Such parallelism of structural features does not, therefore,
demonstrate that the rocks have been thoroughly compressed
subsequent to the syenite-granite intrusions. The northeast-
southwest structural features here referred to are more pronounced
in the Thousand Islands region than is usual throughout the Adiron-
dacks, and this may be readily explained by granting somewhat
greater lateral pressure during the intrusion in the first-named
region. In any case it is necessary to assume only very moderate
compression—far less than would have been necessary to elongate
the batholiths and develop distinct foliation in them after their
complete solidification.
Exceptions to northeast-southwest structure-—There are many
exceptions to the general northeast-southwest structural arrange-
ment, and these prove that no severe tangential compression could
ever have been exerted throughout the region after or during the
intrusions. Among such exceptions are sharp variations in strike
of groups oi inclusions of well-foliated Grenville gneiss in the intru-
sives. Examples have already been cited. If the whole region
has been subjected to compression thoroughgoing enough to flatten
«C,H. Smyth, r5th Ann. Rep. New York State Geologist, 1895, Pp. 491.
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 603
out batholiths and develop foliation after the consolidation of the
magmas, how are these sharp variations in strike of Grenville
inclusions to be accounted for? According to the writer’s view,
such inclusions present no difficulties, because their foliation was
produced prior to the intrusions, and some fragments, especially
those caught up late in the stiff, nearly consolidated magmas with
poorly defined currents, would not have been swung into parallelism
in the uprising magmas.
Also there are important exceptions to parallelism of foliation
of adjacent syenite or granite and Grenville gneisses in relatively
large areas. A few examples will suffice: eastern side of Port
Leyden quadrangle where Grenville with north-south strike is
surrounded with syenite with strike N. 30° E.; northwest corner
of North Creek quadrangle (see geologic map); near northeast
corner of Lake Pleasant quadrangle (see geologic map); northwest
of Indian Lake Village; one mile west of Long Lake Village; and
in the Broadalbin quadrangle where the large areas of Grenville
and adjacent syenite-granite show very different strikes. If the
foliation has been produced by compression after the intrusions,
how are such sharp differences in strike to be accounted for?
Granting the writer’s conception that the Grenville was foliated
prior to the intrusions, and that the syenite-granite foliation was
the result of magmatic flowage, it is to be expected that the mag-
matic currents would occasionally have broken across the Grenville
and its foliation.
Very strong evidence against the development of foliation by
compression of the great intrusives is the frequent occurrence of
sharp variations in the strike of the foliation, often within short
distances. Examination of the Long Lake, North Creek, and Lake
Pleasant geologic maps, upon which foliation strikes are plotted,
shows many strikes in granite or syenite ranging from parallel to
right angles to each other, often within distances of a mile or two.
Similar foliation variations occur upon the writer’s Blue Mountain
and Lake Placid geologic maps, not yet published. How can such
foliation variations possibly be explained as due to lateral pressure ?
Ii due to compression of the whole region, should not the foliation
always strike essentially at right angles to the compressive force ?
604 WILLIAM J. MILLER
If, however, we regard the foliation as essentially a sort of flow
structure, such phenomena are readily accounted for as due to
local variations in the magmatic currents.
Curving strike of foliation—Still another piece of evidence,
though less commonly shown, is the existence of certain broad,
sweeping curves in the foliation of syenite or granite. The North
Creek, Lake Pleasant, and Long Lake geologic maps show such
features. When larger areas of the Adirondacks are mapped in
detail, it is probable that more and better examples will be brought
to light.
_ An excellent case of curving oi foliation on a large scale is in the
Panther-Snowy mountain mass above described as extending nearly
across the southern portion of the Blue Mountain sheet and the
northern portion of the Indian Lake sheet. The great mass of
syenite shows an almost perfect radiation of foliation dips from its
center toward the we&t, north, and east. The only reasonable
explanation of such an arrangement of dips is that the foliation was
produced as a flow structure in the uprising magma, the most rapid
currents having been toward the center of the mass. In the writer’s
opinion, such a large-scale curved arrangement of foliation strikes
and dips not only cannot possibly be explained as due to lateral
pressure, since the foliation would then everywhere be practically
at right angles to the pressure, but also conclusively proves that
no severe compression ever affected the syenite.
Nearly thirty years ago, in his study of the Rainy Lake region,
Lawson described a somewhat similar curved foliated structure in
granite gneiss and said regarding its origin: “‘ The simplest explana-
tion that suggests itself to account for the structure is that of an
uprising force acting on a plastic mass (pasty magma), such force
acting with greatest intensity in the vertical line which would
correspond to the axis of the cone or dome.’””
A similar type of structure appears to be common in the
Haliburton-Bancroft area of Ontario as described by Adams and
Barlow, who say: ‘‘Within the batholiths themselves the strike
of the foliation follows sweeping curves, which are usually closed
and centered about a certain spot. .... From these central aieas
1A. C. Lawson, Ann. Rep. Geol. Surv. Can. (N.S.), III (1887-88), 116.
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 605
of flat-lying gneiss the dip . . . . is generally outward in all direc-
tions. The batholiths, therefore, are undoubtedly formed by an
uprising of the granite magma, and these foci indicate the axis of
greatest upward movement, and those along which the granite
magma has been supplied most rapidly.’
There are not only important variations from the general
northeast-southwest arrangement of the region within the quad-
rangles themselves, but also much broader variations shown
by a comparison of the average foliation strikes of all the quad-
rangles of the Adirondacks which have been mapped in detail.
This is graphically presented by the accompanying sketch map.
Such marked differences in foliation directions on large scales
throughout the Adirondacks is certainly incompatible with any
idea of thoroughgoing compression of the region. Thus in the
Lake Pleasant, North Creek, Blue Mountain, and Saratoga
quadrangles the foliation, either wholly or largely, strikes at high
angles across the general northeast-southwest strike of the
region, while in the Lake Placid quadrangle the strikes are
exceedingly variable. If due to compression, the foliation
strikes would be much more nearly northeast-southwest than they
actually are.
Flow structure character of foliation.—Another significant feature
of the foliation should be mentioned, namely, that, while all the
minerals are arranged with long axes roughly parallel to the direc-
tion of foliation, the dark-colored minerals which accentuate the
structure most often appear as narrow, irregular, wavy streaks
which are seldom continuous for more than a few inches or a foot.
In the writer’s experience this type of foliation is by far the most
common in the syenite-granite series, and it is believed to be the
result of magmatic flowage. Lawson has noted an exactly similar
phenomenon in certain granite gneisses of the Rainy Lake region
of Ontario and says: ‘‘The lines of streaking are very often not
straight but are wavy or contorted, sometimes intricately so, and are
evidently due to flow movements in the magma prior to its final
consolidation.”? As already suggested, flow structures are locally
t Adams and Barlow, Geol. Surv. Can., Mem. 6, 1910, p. 14.
2A. C. Lawson, Geol. Surv. Can., Mem. 40, 1913, P- 93.
606 WILLIAM J. MILLER
very distinctly developed, especially around some of the inclusions
in syenite or granite.
Differences in degree of foliation.—Another important considera-
tion is the frequent pronounced variation in degree of foliation in
the rocks of the syenite-granite series. They are mostly distinctly
gneissoid, rarely so much so as to be almost schistose, while in other
cases they are so faintly gneissoid as to be practically massive. A
striking feature is the frequent rapid change within a few rods or
yards, from rocks which are very clearly gneissoid to others in
which the foliation is scarcely discernible. Sometimes, within a
foot or two, a very gneissoid zone lies between others which are
only moderately foliated. In many cases there is no evidence
whatever of shearing to account for these variations. It seems
impossible to conceive that such abrupt foliation changes could
ever have been produced by severe compression of the rocks after
solidification. Such compression would certainly have brought
about a much more uniform degree of foliation.
According to the writer’s view, these variations are best ex-
plained as due to forced differential flowage in the pasty magmas,
probably after partial consolidation. Regarding the origin of
igneous rock foliation, Pirsson says: “Sometimes this texture has
been imposed upon the igneous rocks after they had solidified, by
intense pressure and shearing, and sometimes while they were still
soft, pasty, and crystallizing, by forced differential flowage, due
to various causes.’”* Those portions of the magma which were
forced in probably a more fluid condition between other, probably
more pasty or solidified, portions would have had a more perfectly
developed foliated structure.
According to Leith: ‘‘Many more schists than gneisses have
been proved to be the result of mashing of igneous rocks. . . . . In
fact, so commonly do the igneous rocks appear when mashed to
take on schistose as contrasted with gneissic structure as to raise
the question whether gneisses are not exceptional results, most
gneisses to be explained as igneous rocks with original flow struc-
tures.’”? The evidence from the Adirondacks is in harmony with
tL. V. Pirsson, Rocks and Rock Minerals (1908), p. 356.
7C. K. Leith, Structural Geology (1913), p. 103.
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 607
this statement by Leith, since anything like true schists are very
rare if not wholly absent’ from the syenite-granite series.
Significance of granulation.—Granulation of the rocks of the
syenite-granite series is of common occurrence. Most of the
mineral constituents are more or less granulated, though it is quite
the rule that the quartz shows the effects of crushing less than the
others. In the greatest bulk of the rock the cataclastic texture
shows itself by flattened or irregular lens-shaped quartz individuals,
and more or less lens-shaped broken feldspars, imbedded in a mass
of small broken feldspar grains together with some crushed quartz
and leaves of mica. In many cases more or less thoroughly
elongated and crushed hornblende or augite also occur.
This granulation has usually been regarded as proof that the
rocks have been subjected to severe lateral compression and
crushing after their consolidation. Thus Smyth, keeping in mind
the frequent lack of crushing of the quartz, has said: ‘‘ As the quartz
could hardly flow while the feldspar fractured, the conclusion is
obvious, and seems to be well grounded, that, in the case of the
quartz, there has been crystallization after the production of
cataclastic structure in the rock.”* But does this prove the quartz
to be largely recrystallized or of secondary origin? Could not
movements in the magma during a late stage of consolidation, and
before much quartz (the last to form) had: crystallized out, have
caused granulation of the earlier-formed crystals, while the quartz
would have been more or less unaffected? In explaining the origin
of foliation in the granite-gneiss of the Thousand Islands region,
Cushing says: “The rock has been much crushed and somewhat
recrystallized under compressive stress, since it originally con-
gealed.”’? Now, while some granulation and recrystallization may
have taken place after the magma consolidation, it is by no means
a necessary inference that the granite has been much crushed and
principally foliated after it had congealed. Strong evidence against
severe compression of the Adirondack region has been presented in
this paper, while the best evidence points to the origin of the folia-
tion as essentially a flow structure developed under moderate
tC. H. Smyth, 15th Ann. Rep. New York State Geologist, 1895, pp. 488-80.
2H. P. Cushing, New York State Mus. Bull., No. 145, 1910, p. 102.
608 WILLIAM J. MILLER
pressure. This being the case, it is only necessary to consider that
there were movements in the slowly cooling and stiffening magma
whereby the minerals already crystallized out were more or less
broken and drawn out into a sort of fluidal arrangement parallel
to the foliation, while the minerals last to form were much less
granulated. A significant point in this connection is that, in rocks
which are definitely known to have been subjected to severe com-
pression, quartz is quite generally more granulated than feldspar.
Both Leith? and Loughlin? have emphasized this point. Now, in
the Adirondack intrusives, as we have shown, the feldspar is very
commonly distinctly more granulated than the quartz, and the
evidence is, therefore, opposed to deformation of the Adirondack
rocks by severe regional compression.
The facts that degree of foliation and granulation often vary
markedly within a few feet or yards, and that the most perfectly
foliated portions are often also the most highly granulated, are to
be expected, because flowage in certain portions of the magma
during the late stage of consolidation would produce in those por-
tions not only good primary foliation but also notable crushing
of the already formed minerals by the movements in the stiff,
pasty magma. It seems impossible to explain satisfactorily such
marked differences in degree of both foliation and granulation in the
syenite-granite series except as the result of movements in the con-
gealing magma. In few cases, if any, is there evidence for shearing,
so that if compression of the region be assumed as the cause of the
foliation and granulation, it is impossible to explain why adjacent
zones often present such differences in degree of foliation and
granulation.
Again, the general lack of notable granulation in the oldest
rocks of the region—the Grenville—is not compatible with the
idea of production of cataclastic structure in the intrusives by lateral
pressure, else why were the still older rocks also not proportionately
affected ?
Other workers have presented strong evidence for the produc-
tion of a granulated or protoclastic texture in igneous rocks by some
™C. K. Leith, U.S. Geol. Surv., Bull. 239, 1905, pp. 33-34-
2G. F. Loughlin, 7bid., Bull. 492, 1912, p. 128.
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 609
such process as that outlined above. Barlow, describing the granite
of central Ontario, says: “‘The movements ... . continued as
the rock cooled and while it was filled with abundant products
of crystallization, the movements being brought to a close only by
_ the complete solidification of the rock. Evidence of protoclastic
structure can, therefore, be seen throughout all the areas colored
as granite or granite-gneiss on the map.’
Teall says, regarding the granite of the county of Kircudbright:
“The quartz and alkali feldspar, which . . . . were the last con-
stituents to solidify, are those which have yielded most to the
deforming stresses. They show signs of crushing..... It is
probable that the pressure acted before the rock mass had actually
cooled.’ :
McMahon, discussing the gneissic granite of the Himalayas,
says: “It is no argument against the idea of the development of
foliation before final consolidation of the granite to point to evidence
of strain and mechanical action in the rock; for the existence of
strain and mechanical action during the critical period in the history
of the granite is an essential part of the theory itself.” He admits
that the granite has been subjected to lateral pressure but says —
that this does not prove the foliation to have been produced by such
pressure.
Weinschenk,’ explaining certain schistose Alpine granites, sug-
gests that, in a somewhat advanced stage of magma consolidation,
a crystalline skeleton is formed whose interstices are filled with
liquid magma. Movements cause crushing of the skeleton,
breaking the feldspars and bending the mica plates. Quartz,
the last mineral to crystallize, is flattened out but not much
broken.
According to Trueman: ‘It seems not illogical to assume that
the movements which were, apparently, present late in the period
of consolidation should have sometimes been continued after por-
tions or the whole of the rock had completely solidified. If such
tA. E. Barlow, Geol. Surv. Can., Mem. 57, 1915, p. 48.
2J. J. H. Teall, Mem. Geol. Surv. Great Britain, Expl. Sheet 5, 1896, p. 43.
3C. A. McMahon, Geol. Mag., N.S., Decade 4, IV (1897), 347.
4E. Weinschenk, Congrés géol. inter., Compte rendu, Session VIII, 1 (1900), 341.
610 WILLIAM J. MILLER
were the case there would result considerable recrystallization and
granulation so that typical crystalloblastic or cataclastic textures
might be superimposed upon that resulting from primary con-
solidation.’”*
The possibility of some granulation and recrystallization in
the Adirondack intrusives after complete consolidation is admitted
by the writer, but, in view of the evidence above presented, such
processes must have had relatively little to do with the development
of the textural and structural features of the rocks.
Cause of mineral elongation.—Still another matter to consider
briefly is the cause of the flattening or elongation of minerals in
the primary gneiss. Flattening or elongation of minerals, espe-
cially quartz and feldspar, are common in the Adirondack intrusives,
varying from rocks in which the phenomenon is scarcely noticeable
to others in which it is extremely developed. It is the writer’s
experience that many such variations exist within short distances.
Quartz exhibits such flattening better and more frequently than the
feldspars. The writer believes that the mineral flattening or elonga-
tion was caused essentially by crystallization in the magma under
pressure. Trueman’ has recently presented considerable evidence
to show that elongation (and presumably flattening) of mineral con-
stituents by crystallization under differential pressure must often
have been a very important factor in the production of foliation of
primary gneisses.
In the Adirondack syenite-granite series, quartz shows the
effects of flattening most because it was the last mineral to crystal-
lize out and hence was not subject to so many of the movements
in the magmas. Loughlin presents a similar argument regarding
the Sterling granite-gneiss of Connecticut as follows: ‘‘ After crys-
tallization had become so far advanced that the rock became a
mass of feldspar crystals (plus a small amount of quartz) with
interstices filled with still fluid quartz, the feldspars would suffer
strain, rotation, and slicing, and become a more or less granular
lens-shaped aggregate elongated in the direction of least pressure.
. . . As the interstitial quartz began to crystallize, it would be
tJ. D. Trueman, Jour. Geol., XX (1912), 2
2 Ibid., XX (1912), 235-42.
FOLIATION IN THE PRE-CAMBRIAN OF NEW VORK 611
obliged to take on the form of the elongated or flattened inter-
stices.’”?
It is not at all necessary to assume a very active lateral com-
pression of the region to account for this pressure. As suggested
by Cushing,’ considerable compression of the magmas must have
resulted from the batholithic intrusions, which, in order to make
room for themselves, exerted a shouldering pressure upon the ad-
jacent rocks. It is believed that such a shouldering pressure within
the magmas was sufficient, not only to cause more or less flattening
and elongation of minerals during consolidation and crystallization,
but also to determine to a considerable extent the directions of the
magmatic currents and hence the resulting strike of the foliation.
Under the very conditions of intrusion, differential pressures must
have been common, thus best explaining the frequent variations
in degree of flattening of mineral constituents. This view does not
of course preclude the possibility of moderate lateral pressure
exerted throughout the whole region during, or even aiter, the
magma consolidation.
Foliation of batholithic borders.—Beiore leaving this. discussion
another feature of the foliation of the intrusive masses should be
mentioned, namely, that they often exhibit a greater degree of
foliation and granulation around their borders than in their interiors.
This phenomenon seems to be best shown in the anorthosite and
the gabbro, and will be discussed below. Suffice it to say here that .
production of foliation and granulation in the congealing magmas
affords a more plausible explanation for the peripheral distribution
of such features than their production by compression of the whole
region.
Summary.—During the process of intrusion, which was long
continued, the great syenite-granite magmatic masses were under
only enough lateral pressure to control the general strike of the
uprising magmas with consequent tendency toward parallel arrange-
ment of syenite-granite and invaded Grenville masses; the foliation
is essentially a flow structure produced under moderate pressure
during the intrusion; the sharp variations of strike on large and
«G. F. Loughlin, U.S. Geol. Surv., Bull. 492, 1912, p. 129.
2H. P. Cushing, New York State Mus. Bull., No. 145, 1910, p. rot.
612 WILLIAM J. MILLER
small scales, and rapid variations in degree of foliation, are essen-
tially the result of varying magmatic currents under differential
pressure, principally during a late stage of magma consolidation;
the almost universal, but varied, granulation of these rocks was
produced mostly by movements in the partially solidified magma,
and possibly in part by moderate pressure applied after complete
consolidation; and the mineral flattening or elongation was caused
by crystallization under differential pressure in the cooling magma.
FOLIATION OF THE ANORTHOSITE
It is not the present purpose to discuss thoroughly the origin
of the structural and textural features of the Adirondack anortho-
site. Only a few of the more important phenomena will be briefly
considered. In general, the explanations above given regarding the
foliation and granulation of the syenite-granite series apply also
to the anorthosite.
Character of the anorthosite-—With the exception of a few small
outlying masses, the anorthosite occupies a practically unbroken
area of 1,200 square miles in the central-eastern Adirondack region.
It quite certainly represents a single great intrusive body which
is older than the syenite-granite series. In its typical develop-
ment the rock consists almost wholly of basic bluish-gray plagioclase
and is very coarse-grained, the feldspars often measuring from one
to several inches in length. There are several important differ-
entiation variations of the great mass. One of these is coarse-
grained, but carries a considerable percentage of dark minerals;
another is finer-grained and more gabbroic looking, owing to dark
minerals, chiefly augite and ilmenite; while still another facies
consists almost wholly of white basic plagioclase, or such white
feldspar and more or less dark minerals. The great bulk of the rock
is highly feldspathic and practically devoid of foliated structure,
probably partly because of lack of minerals favorable for its
production or accentuation, while the more gabbroic (especially
finer-grained) types are almost invariably well foliated, frequently
excessively so.
All of the varieties show more or less granulation, sometimes
to a high degree, this being particularly true of the less coarse-
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK , 613
grained gabbroic types. As regards amount of granulation of
feldspar, it is probably not very different in anorthosite and syenite-
granite. The gabbroic, well-foliated, and granulated facies are
developed on a grand scale around the borders of the great anortho-
site area, but similar types are often encountered irregularly dis-
tributed throughout the area. Large feldspar individuals, usually
unaltered rounded or lens-like cores of crystals, quite typically
stand out prominently in a finer-grained, generally well-granulated,
groundmass. In spite of much granulation, it seems certain that
the typical original rock (before thorough consolidation) was char-
acterized by a coarse porphyritic texture.
Cause of the foliation and granulation.—The foliation and granu-
lation of the anorthosite has been explained as due to the same
severe compression of the region which is supposed to have caused
similar phenomena in the syenite-granite series. According to
this view, the more general lack of anorthosite foliation is considered
to be due to lesser effect of the regional pressure toward the interior
of the great intrusive body than around its borders. Also it is
thought that coarseness of original grain and general lack of min-
erals, especially dark minerals, other than feldspar have militated
against such complete granulation and foliation of the rock as
characterizes the syenite-granite series.
Regarding severe compression after the magma consolidation as
the prime cause of the foliation and granulation is, however, open
to many of the same objections already discussed in connection with
the syenite-granite series. It is the writer’s belief that an insur-
mountable objection to the severe-compression idea lies in the fact
that there are so many sudden variations in degree of foliation and
granulation, and in strike of foliation, throughout the great anortho-
site area. Thus, well within the area, the writer has repeatedly
seen very gneissoid gabbroic facies—both coarse and medium-
grained—in close proximity to gabbroic facies of similar grain with
little or no foliation. All types of anorthosite also often exhibit
varying degrees of granulation in close proximity. If they were
caused by regional compression, why are so many portions highly
foliated or granulated when others close by are unaffected? Also,
if regional compression were the cause of the foliation, how are
614 WILLIAM J. MILLER
the frequent very notable variations in strike, often within relatively
small areas, to be accounted for ?
According to the general principles outlined in connection
with the foregoing discussion of the syenite-granite series, it is the
writer’s conception that the foliation and granulation of the anortho-
site were developed essentially by flowage or other movements in
the magma under moderate pressure, mostly just prior to its com-
plete consolidation. As Cushing has said regarding the Long Lake
quadrangle anorthosite: ‘In some portions of the rock the feldspar
crystals are more numerous, are smaller and are all arranged with
their long axes parallel. This is a ‘flow structure’ due to move-
ments in the mass during solidification.’ The better foliated or
better granulated belts throughout the great mass represent merely
places where the magmatic currents or other movements were more
pronounced. The coarser-grained portions would of course have
undergone less complete granulation, but coarseness of grain and
absence of dark minerals would not necessarily have tended to
prevent the development of foliation. Thus, in the Broadalbin,
North Creek, and Lake Pleasant quadrangles the writer has
observed coarse granite-porphyry, almost free from dark minerals,
with highly gneissoid structure due to thorough flattening out of
both quartz and feldspar, while in other cases the porphyry shows
little or no foliation. It would seem, therefore, that the general
absence of foliation throughout so much of the anorthosite is best
explained as the result of the much more uniform intrusion of this
single great body which is less involved with Grenville masses, or,
in other words, to much less forced differential flowage. Because
of its great size, the pressure due to shouldering effect on adjacent
rocks would be relatively slighter toward the interior of the
mass.
Not only is the foliation well developed around the margin of
the great intrusive, but it also appears to be especially well exhibited
in many parts of the area in the gabbroic facies where they are close
to masses or inclusions of Grenville. Just as flow structure is often
best shown close to the wall-rock of, or an inclusion in, a small
intrusive body, probably because of friction against the wall-rock
tH. P. Cushing, New York State Mus. Bull., No. 115, 1907, p. 472.
FOLIATION IN THE PRE-CAMBRIAN OF NEW VORK 615
or inclusion and consequent development of differential pressure
and flowage, so, on a large scale, in the anorthosite body it is
reasonable to think that foliation due to magmatic flowage would
have been best developed around the margin of, or close to, masses
of country rock within the great anorthosite body. In many
other places, however, primary gneissoid structures may have been
produced by differential flowage far from any country rock.
The cataclastic texture of the anorthosite is believed to have
resulted from the crushing of minerals already crystallized out of
the stiff, solidifying magma by movements in the magma. The
shouldering pressure exerted by the great intrusive mass in order
to make room for itself must have been sufficient to have affected
the whole mass until final consolidation.
Kemp says, regarding the anorthosite of the Elizabethtown
quadrangle: ‘The entire area has been subjected to such severe
pressure and granulation that the outer borders oi the crystals
are always crushed to a finely granular and whitish mass. Within
this rim the bluish nuclei of the plagioclases remain. When shear-
ing and dragging have been added the nuclei yield augen-gneisses.’”*
It is, however, not at all necessary to assume severe regional pres-
sure to account for these phenomena. Forced differential flowage
in the stiff, nearly congealed magma (under pressure due chiefly
to its own shouldering action) could have produced most, if not all,
of the granulation and dragging effects, the “‘augen”’ being cores
of what were large, probably porphyritic, feldspars in the nearly
solidified magma. Moderate pressure during or even after con-
solidation may possibly have operated to accentuate the phenomena.
Adams says, concerning the Morin anorthosite north of Mon-
treal: ‘‘The circumstance that the streaks or irregular bands
(foliation), when present in the otherwise massive rock, assume no
definite direction, but twist about as if owing to movements oi
the rock while in a pasty condition, indicate that they have been
produced by movements before the rock solidified... . . The granu-
lation of the coarsely crystalline massive anorthosite, usually with
concomitant development of more or less foliated or schistose
structure in the way described, is undoubtedly due to movements
tJ. F. Kemp, New Vork State Mus. Bull., No. 138, 1910, p. 28.
616 WILLIAM J. MILLER
in the rock, resulting from pressure which acted subsequent to
or possibly during the last stages of its consolidation.’
FOLIATION OF THE GABBRO
The gabbro here considered is the latest Adirondack intrusive
which exhibits foliation and granulation. Diabase is the only
intrusive still younger. A few years ago the writer? discussed the
origin of certain primary variations of Adirondack gabbro. At that
time, in accordance with the usual idea, the foliation was thought
to be largely a secondary structure and so was omitted from the
discussion.
Character of the gabbro.—Most of the gabbro is in the form of
small stocks or bosses, the outcropping areas typically ranging from
elliptical to almost circular, and the dimensions from a few rods
to one or two miles. They are especially well-shown on the North
Creek, Long Lake, Elizabethtown, and forthcoming Blue Mountain
geologic maps. Most of them are of pluglike or pipelike form, with
practically vertical, sharp contacts against the country rock. The -
stocks exhibit many variations in composition and texture from the
normal, homogeneous, dark, basic gabbro with diabasic texture,
to lighter-colored rocks of. dioritic and even syenitic make-up.
They also range from fine-grained to very coarse-grained with feld-
spars up to an inch or more in length. The typical gabbro con-
tains principally basic plagioclase, pyroxene, hornblende, biotite,
garnet, and ilmenite, while orthoclase and quartz often occur
in the more acidic facies.
A very important feature, from the standpoint of our present
discussion, is the almost universal development of highly foliated
amphibolitic borders which often completely surround the stocks,
while the interior portions of the typical stocks are usually non-
foliated. In many cases, however, stocks seem to be wholly
changed to amphibolite, or only very small cores remain. In
still other cases coarse-grained gabbro shows gneissoid structure
thoroughly developed throughout. As a rule the gabbro exhibits
as good, ‘{ not better, foliation than the older intrusives. Often
tF, D. Adams, Geol. Surv. Can., Guide Book No. 3, 1913, Pp. 17-
2W. J. Miller, Jour. Geol., XXI (1913), 160-80.
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 617
the degree of foliation varies much even well within single
stocks. :
Another very persistent feature is granulation which appears
to be of two types, that of so-called “corrosion rims” around certain
minerals, and a more generally distributed granulation. Granu-
lated “corrosion rims” occur even in non-foliated gabbro with
diabasic texture.
Cause of foliation and granulation.—The foliation and granula-
tion of the gabbro, like that of the older intrusives, are quite gen-
erally regarded as secondary features brought about by the influence
of regional pressure, the non-foliated, uncrushed cores of stocks
being considered as portions protected from pressure influence.
Granting the existence of regional compression severe enough to
give rise to these phenomena, it is evident that the same pressure
must have affected the older intrusives in a similar manner, but
this we have proved to be not the case. It is very difficult to
imagine a process of development of foliation, which boxes the
compass around the borders of the gabbro stocks, by regional com-
pression. Such foliation of course often strikes directly across the
foliation of the older adjacent rocks, an excellent case in point being
at the south end of the large stock just north of Loon Lake of the
North Creek sheet. How can such phenomena be explained as
due to regional pressure when it is well known that cleavage or
foliation produced by this means must everywhere strike at least
approximately at right angles to the direction of application of
pressure? Also how are such frequent notable variations in
foliaton and granulation, not oniy in near-by stocks but also
within stocks, to be explained ?
According to the thesis of th’s paper, the foliation and granula-
ton are largely, if not wholly, primary features. There are,
admittedly, some puzzling things about the foliation and granula-
tion of the gabbro, but certainly they are to be much more reason-
ably interpreted as caused by movements in the magma before
complete consolidation.
Weinschenk, in explaining schistose peripheral zones around
certain Alpine granitic cores, has suggested: ‘The consolidation
of the rock commenced with the separation of the dark minerals—
618 WILLIAM J. MILLER
biotite and hornblende. Mica formed first in the liquid mass.
At this time the orogenic pressure acted upon the peripheral zone
of the magma by orienting this minera! normal to the pressure. In
the heart of the viscous mass this faculty of orientation was
replaced by an interior tension not directed in any particular way.’
Orogenic pressure did not exist in the Adirondack region, but if for
it we substitute the pressures within the stock magmas themselves,
this idea of Weinschenk affords a plausible explanation of the foliated
borders. Considerable pressures must have obtained within the
stock magmas which were intruded under very deep-seated con-
ditions. Such pressure against the country rock, combined with
the usual development of differential flowage in the magmatic
borders, as already explained in this paper, would readily account
for the peripheral foliated zones which were produced, no doubt,
during a late stage of magma consolidation. But the conditions
for magmatic pressure and flowage must often have varied a great
deal, so that it is to be expected that, in some cases, even coarse-
grained gabbro would exhibit primary foliation, while, in other
cases, amphibolite would make up the whole mass, or, in still other
cases, finer-grained, very gneissoid, and granulated belts or bands
would occur in the midst of coarser, less foliated types. It should
be noted in this connection that unmistakable flow structures do
often occur around inclusions in the gabbro.
Applying these ideas, the puzzling features of various gabbro
stocks find a ready interpretation. A good example is the stock
near Blackbridge in the Lake Pleasant quadrangle. For most
part this is a very basic, gabbroic-looking rock, sometimes pretty
massive and very coarse-grained, and at other times not so coarse,
but streaked or almost banded, owing to layers of amphibolite.
All phases of the rock are much granulated and distinctly gneissoid,
the coarser-grained portions being least so. A diabasic texture
frequently occurs. Differential flowage and other movements
under pressure in the congealing magma best explain these phenom-
ena. The more foliated, finer-grained belts in the midst of the
«E. Weinschenk, Congrés géol. inter., Compte rendu, Session VIII, 1 (1900), 340.
Freely translated from the French.
2W. J. Miller, New York State Mus. Bull., No. 182, 1916, p. 29-30.
FOLIATION IN THE PRE-CAMBRIAN OF NEW YORK 619
coarser, less foliated rock may be readily interpreted as the result
of a forcing of slightly more liquid portions of the congealing magma
through more solidified portions.
Highly developed ‘‘corrosion rims”’ are beautifully and exten-
sively developed in the Adirondack gabbros.t. Their occurrence
even in non-joliated gabbro with diabasic texture argues strongly
for their production before final consolidation of the magma, this
possibility having been recognized by other investigators. How
could regional compression have caused so much of this sort of
granulation without otherwise affecting the rock ? Also, if granula-
tion of this sort has resulted from movements prior to solidification
of the magma, why could not the more general cataclastic textures
of the syenite-granite, anorthosite, and gabbro have been similarly
produced? As in the older intrusives, so in the gabbro, the
finer-grained more foliated portions are quite generally the most
granulated, this doubtless resulting from more pronounced flowage
movements in certain portions of the magma late in the process
of consolidation.
tW. J. Miller, Jour. Geol., XXI (1913), 168-70.
THE COMPOSITION OF THE AVERAGE IGNEOUS ROCK*
ADOLPH KNOPF
U.S. Geological Survey, Washington, D.C.
The composition of the “‘average igneous rock”’ has been com-
puted by Clarke, Harker, and Washington. Clarke’s most recent
estimate was published in 1915.2, The earlier computations were
made by averaging the results of large numbers of analyses, and the
later by averaging each constituent according to the number of
determinations made, and reducing the sum to too per cent.
The objection to these methods, as is well known, is that they
take no direct account of the quantitative distribution of the
rocks; each analysis or determination receives the same weight,
regardless of the size of the geologic body that it is held to repre-
sent. The force of this objection has been recognized by
Clarke,s who concludes that ‘‘the whole land surface of the earth
must be taken into account before the true average can be finally
ascertained.”
A first approximation to this true average can be reached by
calculations based on data recently assembled by Daly in [gneous
Rocks and Their Origin. In Table IV is given the total areas —
covered by each of the rock species named and mapped in the
Cordilleran and Appalachian folios of the United States Geo-
logical Survey. The area occupied by any rock species divided
by the total area of igneous rocks (16,728 square miles) gives a
weight-factor, and this factor multiplied by the average composi-
« Published with the permission of the Director of the U. S. Geological Survey.
2 Analyses of Rocks and Minerals from the Laboratory of the United States Geo-
logical Survey, U.S. Geological Survey Bulletin, No. 591, pp. 18-22, 1915.
3 The Data of Geochemistry (3d ed.), U.S. Geological Survey Bulletin, No. 616,
p. 26, 1916.
620
COMPOSITION OF THE AVERAGE IGNEOUS ROCK 621
tion of the species, which has been computed by Daly in Table I,
gives the percentage contribution of that species to the composition
of the average igneous rock. In this calculation species covering
less than 2 square miles were omitted, as their inclusion would not
affect the second decimal place of the result. The composition
thus calculated is that of the average exposed igneous rock; whether
it represents the composition of the average igneous rock of the
to-mile crust depends on the verity of certain petrogenic considera-
tions.
The following proportional factors were used in the computa-
tions:
Granite, including allied porphyries....... 0.23212
Granodionite pyr ter. Cele ele tals HL2TOS
Rihvioliteneane nace Bette es bk dah ee ts . 12834
INTIMeSIVE Men re tn tee eels rsa ei eee Soe . 23864
TRESS YAS Bets BO meee Coie ee ee . 20773
Quartz monzonite and allied porphyry..... .oo108
Dignity yey Peer ey el aacs .01802
Gab Drones erent ee eee ak .02225
PATOL OSC pete eee nee eet siece) 3c ehsjie kare .003II
Syenite and syenite porphyry............. .00389
Non ZO mire merrier eet eee Sm se a esce gees .OO161
iNephelinersyenitemmri arts cr cerca teeerrr. .00024
Shrombsimibe meron rsa esc arte icr els a ace oie .00054
TRY aye seee TES og WEN ale ata reas Arm a . 00036
IP SCIGIOIE NCES ce oktroca's o-8 Oia ane remem eS .00436
Ey KOXEMILE Hemera. ne tsisai 2). so maka .OOOTI
WDiabasewew errr yn teria Surshes sia als .01602
Wa citeury re Meee onin ie eit ie ect sucha .00536
TS PACMAG) Necture) aie crcl ocdia eke le cee ep ech ee ie .00036
Waterers tna asc Oye eter ik Gite . 00030
IPhonoliter een mele ie eee hee he .00048
iINephelinemmelilite:basalt (43 )s 2 .00018
[Gimp ungate warmest kee eis ce. ss uk ake .O00T2
otal rere sac uncucuaes eis A Cas I .00000
The result of the new calculation of the composition of the
average igneous rock is given in column I of the accompanying
table; for comparison, the most recent estimate by Clarke is given
in column II.
622 ADOLPH KNOPF
Notwithstanding the widely different methods employed in the
calculations the new estimate agrees to a remarkable extent with
COMPOSITION OF THE “AVERAGE IGNEOUS ROCK”
I II
SiOx. 2 Ue eee 61.64 60.47
WMO2.: tee eee Os73 0.80
ALLO}. inte eee m5 70 E5407
FeO; 55 Oe 2.91 2.68
1 Oe. errmreen cattndts clnises tttee B25 su5O
MnO. e 8 2k aseeeaee 0.16 0.10
MeO) ociccls Deere 2°07 3.85
GCaOs* eee ee 5.06 4.88
INaO)s 735 eee 3.40 3.41
KO... Eee ee 2.65 3.03
ELO= >. Oa it 6 f 0.48
HO. : 2 ee if aah \ 1.44
BLO gs «cea 0.26 0.29
100.00 100.00
Clarke’s average. The most notable departures are the increase in
silica and the relatively strong decreases in magnesia and potassa.
REVIEWS
The General Magnetic Survey of the Earth. By L. A. BAUER. Bull.
Am. Geog. Soc., XLVI, July, 1914, pp. 481-09. Figs. 6.
About the earth sphere are lines of magnetic force very similar to
those of any magnetic field, their poles not quite coincident with those
of the earth axis. That the magnetic needle varies from true north
was discovered at least as early as the fifteenth century, when Columbus
sailed west from Europe. Subsequent observations have shown in
addition that there is a constant change in the earth’s magnetism, mak-
ing repeated magnetic surveys necessary. In magnetic observations,
the horizontal declination, vertical magnetic dip, and intensity of the
attraction are measured. Since 1904 the Carnegie Institution of Wash-
ington has conducted extensive magnetic surveys of the earth in which a
total mileage of approximately one million miles has been traveled.
Ocean surveys have been conducted in a specially constructed non-
magnetic vessel.
IR (Co IML
The Mud Lumps at the Mouths of the Mississippi. By EUGENE W.
SHAW. U.S. Geol. Surv., Prof. Paper 85, Part B, 1913. Pp.
17, pls. 3, figs. 6.
The territory within a mile or two of each of the mouths of the
Mississippi is characterized by large swellings or upheavals of tough
bluish-gray clay, to which the name “mud lumps”’ has been applied.
Many of the mud lumps rise just off-shore and form islands having a
surface extent of an acre or more and a height of 5 to 10 feet, but some
do not reach the water surface. Almost all occur near the bars at the
mouths of the rivers. In contrast with the general structure of the delta,
which is composed of thin, alternating sandy and clayey beds, the mud
lumps are of thick, compact clay. On and around the clay core lies a
series of faulted and folded strata of sand and silt which have been
carried up from the sea bottom and deformed in the upheaval. It seems
most likely that these lumps owe their origin to a squeezing of the soft
layers, and an accumulation of clay from such layers in places where the
pressure is less strong. This postulates a gentle seaward flow of layers
623
624 REVIEWS
of semifluid clay, the flow meeting resistance particularly at the ends of
the Passes, where there is an accumulation of more resistant material
and a greater lack of equilibrium between the heavy land on one side
and the water on the other. The report is somewhat preliminary in
nature.
R;, CyMe
The Upper Cretaceous and Eocene Floras of South Carolina and
Georgia. By EW. Berry.: U.S. Geol. Sury., Prot gen
84, 1914. Pp. 200, pls. 20, figs. 12.
The Upper Cretaceous of South Carolina is represented by the Black
Creek formation, which is divisible into two members, the Middendorf
arkose, with certain related clays, and. a sandy, marine member. A
number of localities in the Middendorf have yielded plant remains, among
which are found magnolias, figs, laurels, oaks, walnuts, cinnamon, the
eucalyptus, etc. The collection numbers 75 species. The climate,
indicated by the types present, is subtropic, or at least mild temperate,
for with little variation the flora extends to the western coast of Green-
land.
The Upper Cretaceous of Georgia, the flora of which is described in
the second part of the paper, is confined to a triangular area lying west
of the Ocmulgee River and comprises the eastward extension of the
Eutaw and Ripley formations. The former contains an abundant fossil
flora in its lower division, but the latter, except in the upper part, con-
tains little plant life. The physical conditions suggested are in accord
with the evidence from South Carolina and point to a mild, humid
climate, without frosts.
A small but very interesting Middle Eocene flora from Georgia is
described in the third division of the paper. The Middle Eocene of
Georgia is for the greater part deeply buried beneath younger sediments,
but in the area lying between the Ocmulgee and Savannah rivers there
are outcrops which have yielded a fossil flora of 17 species. Most of these
have not been described previously and the author compares them with
European Eocene and modern related types. The conclusion is reached
that the Middle Eocene of this region enjoyed a much more tropical
climate than is represented by any other known ‘Eocene flora. The
Georgia flora was probably immigrant from the south and reached
northward at least as far as latitude 33° N.
Ri Coe
Excursion on the Rock River of
Illinois between Rockford and
Dixon
Price to cents
and
Excursion through the Rivers and
Harbor of Chicago Price 10 cents
These are two of the seven
~ Bulletins of the Geographic —
Society of Chicago.
Teachers of biology and
geology will find them of
especial importance for field
trips, lectures, —
Write for descriptive circulars.
The University of Chicago Press
Chicago - eet -
Illinois
ordering by telegraph.
_ library use will find this catalogue helpful.
. 354 Fourth Avenue
A New Edition of our Caries of
: SCHOOL AND COLLEGE TEXTBOOKS
Now Ready for Distribution
THE BAKER & TAYLOR CO.
Wholesale dealers in the books of all publishers
NEW YORK
Do You Want to Know
What Your Handwriting
‘Reveals? _
: \ X 7 E have published a fascinating
booklet of 32 pages on the sub-
ject of graphology, by William Leslie
French. Every reader of this publi-
cation will be interested in comparing
the examples of handwriting in judg-
ing character and disposition of the
writer.
A copy of this booklet and 12 differ-
ent patterns of The Spencerian
Steel Pens will be sent postpaid on
receipt of ten cents.
If you can do good work with a poor pen
you can do better work with a good pen.
Silver plated Falcon pens, smooth points,
. wear long, will not corrode.
SPENCERIAN PEN CO.
349 Broadway - - - New York City
Asin previous issues of this catalogue, we have listed all the important textbooks
on all subjects, arranged alphabetically by author.
book is indicated, and a telegraph code word is given for the convenience of those
The wholesale list price of each
A subject index to the more important books listed is preted:
The best students’ texts for the study of the English and American classics recom-
_. mended for secondary schools and required for college-entrance examinations are
a conveniently listed for quick reference and comparison.
The text editions of the French and German classics used most widely in high
schools and colleges are given space; and handy literal and interlinear translations of
Latin, Greek, French, and German texts are included.
Everyone upon whom devolves the responsibility of ordering books for class or
It will be sent free on request.
At Twenty-Sixth St.
All Essentials of
Optical Superiority
Besides wide variety of models and_ practical
improvements in equipment, genuine optical
superiority is manifest in
Rausch lomb
Microscopes
They are the product of an experience of over
sixty years in every phase of optical manufacture
and have withstood the most exacting tests.
Model FS2 (illustrated) has our lever type of side
fine adjustment, gives unusual space for object
manipulation, and is finished in our new crystal
black—reagent-proof and more durable than the
ordinary lacquer. Price, $34.00.
Simple microscopes from $2.50 up—compound models -
from $18.00 up.
Special terms to Educational Institutions.
Write for descriptive, illustrated price lists of Microscopes
; A pes,
Accessories, and Microscope Lamps
Bausch £9 Jomb Optical ©.
412 ST. PAUL STREET ROCHESTER, N.Y.
New York Chicago Washington San Francisco
Leading American Makers of Photographic Lenses, Binoculars,
parrot Lanterns (Balopticons) and other high-grade optical
products. i
the very latest addition to the great
Remington family of typewriters. Anew —
and smaller Remington—built for the
needsof the professional man and thehome
Mail this eaunan today
\
It is the
Remington | | :
within ten days.
$5 each.
Remington Typewriter Company
(Incorporated)
327 Broadway, New York
Send me a Remington Junior Typewriter, |
price $50, on free examination. Itis understood
that I may return the machine, if I choose,
If I decide to purchase it, I
agree to pay for it in 10 monthly payments of
FINE INKS 4%» ADHESIVES
For those who KNOW
Higgins’
Are the Finest and Best Inks and Adhesives
Emancipate yourself from the use of corrosive and
ill-smelling inks and adhesives and adopt the
Higgins Inks and Adhesives. They will bea
revelation to you, they are so sweet, clean, well
put up, and withal so efficient.
At Dealers Generally
CHAS. M. HIGGINS & CO., Mfrs.
Branches: Chicago, London
271 Ninth Street
Drawing Inks
Eternal Writing Ink —
Engrossing Ink
Taurine Mucilage —
Photo Mounter Paste
Drawing Board Paste
Liquid Paste
Office Paste —
Vegetable Glue, Etc.
Brooklyn yNni¥.
2 2 4 r | A 4
A New Proposition |
A TYPEWRITER BY PARCEL POST
ON TEN DAYS’ FREE EXAMINATION ~
ee HEN Fi
_ VOLUME XXIV ie . NUMBER 7
THE
JOURNAL or GEOLOGY
A a QUARTERLY
EDITED By
_- +, ~~ ‘THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
With the Active Collaboration of
SAMUEL Ww. WILLISTON, Vertebrate Paleontology ALBERT JOHANNSEN , Petrology
STUART WELLER, Invertebrate Paleontology ROLLIN T. CHAMBERLIN, Dynamic Geology
ALBERT D. BROKAW, Economic Geology
ASSOCIATE EDITORS
SIR ARCHIBALD GEIKIE, Great Britain JOSEPH P.IDDINGS, Washington, D.C.
CHARLES BARROIS, France JOHN C, BRANNER, Leland Stanford Junior University
ALBRECHT PENCK, Germany RICHARD A. F. PENROSE, Jr., Philadelphia, Pa.
HANS REUSCH, Norway f WILLIAM B. CLARK, Johns Hopkins University
GERARD DEGEER, Sweden : WILLIAM H. HOBBS, University of Michigan
T. W. EDGEWORTH DAVID, Australia FRANK D. ADAMS, McGill University
BAILEY WILLIS, Leland Stanford Junior University CHARLES K. LEITH, University of Wisconsin
GROVE K. GILBERT, Washington, D.C. WALLACE W. ATWOOD, Harvard University
CHARLES D. WALCOTT, Smithsonian Institution — WILLIAM H. EMMONS, University of Minnesota
HENRY S. WILLIAMS, Cornell University ARTHUR L. DAY, Carnegie Institution
.
OCTOBER-NOVEMBER 1016
THE GENESIS OF LAKE AGASSIZ: A CONFIRMATION - - - W. A. JOHNSTON 625
THE LOWER EMBAR OF WYOMING AND ITS FAUNA - - - E. B. BRANSON 639
EVOLUTION OF THE BASAL PLATES IN MONOCYCLIC CRINOIDEA CAMERATA. III
HERRICK E. WILSON 665
DISCOVERY OF THE GREAT LAKE TROUT, CRISTIVOMER NAMAYCUSH, IN THE
PLEISTOCENE OF WISCONSIN - - - - = - - - L. Hussakor 685
ASSUMPTIONS INVOLVED IN THE DOCTRINE OF ISOSTATIC COMPENSATION,
wi A NOTE ON HECKER’S DETERMINATION OF GRAVITY AT SEA
WILLIAM HERBERT HoBsBs 690
A STAGE ATTACHMENT FOR THE METALLOGRAPHIC MICROSCOPE
ALBERT D. BRoKAW 718
REVIEWS - Ci HW AR RN ER Ra PR NPSL fas ln UeM BALA ln 22
see's THE- LOEWE RS Ey yOrR CHICAGO PRESS
CHICAGO, ILLINOIS, U.S.A.
AGENTS
THE CAMBRIDGE UNIVERSITY PRESS, London anp EDINBURGH
KARL W. HIERSEMANN, LErpzic
THE MARUZEN-KABUSHIKI-KAISHA, Toxyo, Osaka, Kyoto, FukuOKA, SENDAI
THE MISSION BOOK COMPANY, SHANGHAI
“ ” = * .
THE JOURNAL OF GEOLOGY
EDITED By
THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
With the Active Collaboration of A Spy be
SAMUEL W. WILLISTON ALBERT JOHANNSEN
Vertebrate Paleontology Petrology
STUART WELLER ROLLIN T. CHAMBERLIN =
Invertebrate Paleontology Dynamic Geology
ALBERT D, BROKAW
Economic Geology '
The Journal of Geology is published by the University of Chicago at the University Press semi-
quarterly, on or about the following dates: February 1, March 15, May 1, June 15, August 1, September 15,
November 1, December 15. {] The subscription price is $4.00 per year; the price of single copies is
65 cents. Orders for service of less than a half-year will be charged at the single-copy rate. 4] Postage is
prepaid by the publishers on all orders from the United States, Mexico, Cuba, Porto Rico, Panama Canal
Zone, Republic of Panama, Hawaiian Islands, Philippine Islands, Guam, Samoan Islands, Shanghai,
{| Postage is charged extra as follows: For Canada, 30 cents on annual subscriptions (total $4.30), on
single copies, 4 cents (total 69 cents); for all other countries in the Postal Union, 53 cents on annual
subscriptions (total $4.53), on single copies, 11 cents (total 76 cents). Patrons are requested to make
all remittances payable to the University of Chicago Press in postal or express money orders of bank
drafts. bsg wae
The following agents have been appointed and are authorized to quote the prices indicated: .
For the British Empire: The Cambridge University Press, Fetter Lane, London, E.C. boned
subscriptions, including postage, 18s. 8d, each; single copies, including postage, 3s. 2d. each,
For the continent of Europe: Karl W. Hiersemann, Kénigstrasse 29, Leipzig, Germany. Yearly
subscriptions, including postage, M. 22.65 each; single copies, including postage, M. 3.80 each.
For Japan and Korea: The Maruzen- Kabushiki- Kaisha, 11 to 16 Nihonbashi Tori Sanchome,
Tokyo, Japan. Yearly subscriptions, including postage, Yen 9.00 each; single copies, including
postage, Yen 1.50 each.
For China: The Mission Book Company, 18 Peking Road, Shanghai. Yearly subscriptions,
$4.00; single copies, 65 cents, or their equivalents in Chinese money. Postage extra, if mailed direct
outside of Shanghai, on yearly subscriptions 53 cents, on single copies 11 cents. Mb nigel
Claims for missing numbers should be made within the month following the regular month of
publication. The publishers expect to supply missing numbers free only when they have been lost in
transit. : ;
Business correspondence should be addressed to The University of Chicago Press, Chicago, Ill.
Communications for the editors and manuscripts should be addressed to the Editors of THE
JOURNAL OF GEOLOGY, the University of Chicago, Chicago, Ill.
Contributors are requested to write scientific and proper names with particular care and in citations
to follow the form shown in the pages of the Journal.
Separates, if desired, must be ordered in advance of publication. Separates of leading articles will be
printed as ordered, of which 50 (without covers) will be furnished grafis, the actual cost of the remainder
(and covers, if desired) to be paid for by the author. The actual cost may vary, and will depend upon
the amount of work in re-making the pages into forms, presswork, paper, binding, etc. Separates
containing half-tones may be expected to cost somewhat more, the increase depending i ae the number
of cuts and the amount of work required upon them. MR
Entered as second-class matter, March 20, 1893. at the Post-office at Chicago, Ill., under the Act of March 3, 1879,
VOLUME XXIV NUMBER 7
THE
JOURNAL OF GEOLOGY
OCTOBER-NOVEMBER 1916
THE GENESIS OF LAKE AGASSIZ: A CONFIRMATION
W. A. JOHNSTON
Canada Geological Survey, Ottawa, Canada
CONTENTS
DSR OTTO CATON Jao, Bs HS OS cao Coc ORR a IP Pec Giger 625
UpHam’s CONCEPTION OF THE LIFE-HISTORY OF LAKE AGASSIZ....... 626
DIFFICULTIES IN ACCEPTING UPHAM’S INTERPRETATION.............. 627
RECORDS OF LAKE Acassiz IN Ratny RIVER-LAKE OF THE Woops DIs-
THEGUCA 4) 3 ici 2 ond wid wit o Bore, O°el aha LOLY Dadi Aan PE see eS NRE 629
CrocrArHICAT RELATIONS OF THE, DISTRICT)... 4.044 4 cence eae 629
SSL T SELES meee een Paellts, we aliren vista) ale 5. Wc le) Sud af cyallats) aha; Seheral coe erie apout g 630
LO ANMINVACEE DD BS ON Wal © HAWS Mieepeii sos: Akar. iiss cave wel oe evasela, sels aueteaiane es 630
DEP OSMSROE MUAKE WNGAGSIZ Mee ge 5) olai icici clad ts a wiotmmicle etc cvslans 631
UNCONFORMITY AT THE BASE OF LAKE AGASSIZ SEDIMENTS........ 632
BEARING OF THE LIFE-History OF LAKE AGASSIZ ON THE QUESTION OF
THE CHARACTER AND CAUSE OF THE DIFFERENTIAL UPLIFT....... 636
SHURE sn Ba che cles 8 pio ators nc ea TEI Oe ge aac Uo aa 638
INTRODUCTION
In a paper published in the Journal of Geology in 18096, J. B.
Tyrrell stated that the results of his field work in the region lying
to the west and southwest of Hudson Bay showed that—
the Keewatin glacier seems to have retired northward well into Manitoba and
possibly even beyond the northern limit of that province before it was joined
by the eastern glacier. When they united the water was ponded between the
t Published by permission of the Director of the Geological Survey of Canada.
Vol. XXIV, No. 7 ‘ 625
626 W. A. JOHNSTON
fronts of the two glaciers to the north and northeast and the high ground to
the south and west. Thus Lake Agassiz had its beginning. Its waters
rapidly rose until they overflowed southward into the valley of the Mississippi
and then gradually declined as River Warren deepened its channel.
By his more recent work in the region lying to the south of
Hudson Bay, Tyrrell has shown that the last invasion of glacial
ice in that region was by an ice sheet which advanced in a south-
westerly direction and overlapped a portion of the area previously
occupied by an ice sheet which he named the Patrician Glacier.
This last advance of the ice extended in a southwesterly direction
at least as far as the headwaters of the Severn River and in a
westerly direction approximately as far as the Hayes River, where
it was met by a readvance of the Keewatin glacier.’
Field work done by the writer during portions of the seasons
of 1913 and rorq in the vicinity of the Rainy River and Lake of
the Woods, Ontario, has brought forth evidence which confirms
Tyrrell’s view that Lake Agassiz had at first a rising stage, due to
the blocking of the northward drainage, and later subsided, and
that, during the entire existence of the lake, the ice border was far
to the north and northeast. This conception of the life-history of
Lake Agassiz differs radically from that of Warren Upham, by
whose work Lake Agassiz is best known, and whose interpretation
has been most widely accepted. The object of the present paper
is to present the evidence which confirms Tyrrell’s view as to the
genesis of Lake Agassiz and to point out that the acceptance of this
view has an important bearing upon the question of the character
and cause of the epeirogenic movements which deformed the shore
lines of Lake Agassiz.
UPHAM’S CONCEPTION OF THE LIFE-HISTORY OF LAKE AGASSIZ
Glacial Lake Agassiz is best known from the work of Warren
Upham, the results of which were published in 1895 by the United
States Geological Survey as Monograph 25. Upham’s field work
in connection with the investigation of the basin of Lake Agassiz
was done some thirty years ago and was largely confined to the
tJ. B. Tyrrell, ““The Genesis of Lake Agassiz,’ Jour. Geol., IV (1806), 813.
2 J. B. Tyrrell, ‘The Patrician Glacier South of Hudson Bay,’’ Congrés Géologique
International, Canada, 1913, Compte-Rendu (Ottawa, Canada, 1914), pp. 523-34.
THE GENESIS OF LAKE AGASSIZ 627
_ western or prairie portion of the basin. At that time little was
known of the extension of the lake in the northern portion of the
state of Minnesota or in the adjoining portions of Canada, for much
of this region was densely wooded, largely unsettled, and difficult
of access. At that time, also, the general conception was that
during Pleistocene time the Laurentide glacier occupied the greater
portion of Central and Northwestern Canada. It was not until
‘some time later that the subdivision into Keewatin and Labra-
dorean ice fields was recognized.
Upham believed, as the result of his investigations, that the
northward drainage of Red River valley and adjacent areas was
ponded between the retreating front of the Laurentide glacier on
the north and northeast and the divide on the south, that the lake
had at first a small beginning in the southern part of the basin and
gradually grew in size as the ice withdrew toward the northeast,
and that a great series of moraines was deposited in the waters of
the lake at stages of halt or slight readvance during the general
retreat of the ice sheet. He found that the lake, during its higher
stages, discharged southward to the Mississippi along the course
of the present Lake Traverse and Minnesota River valleys. Dur-
ing the operation of the southern outlet several strong shore lines
of the lake were developed. As the ice retired and uplift took place,
lower outlets were opened toward the northeast and other and
lower beaches were developed in the northern part of the basin.
He also showed that beaches which are single in the southern por-
tion of the basin split into series in the northern portion of the basin
and rise differentially toward the north-northeast, the highest being
most upwarped and the lowest least, thus proving that differential
elevation of the land went on during the existence of the lake.*
DIFFICULTIES IN ACCEPTING UPHAM’S INTERPRETATION
Some of the difficulties involved in accepting Upham’s inter-
pretation of the life-history of Lake Agassiz were pointed out by
T. C. Chamberlin. It was found by Upham that the uppermost
or Herman beach was continuous for a long distance northward
t Warren Upham, ‘“‘The Glacial Lake Agassiz,” U.S. Geol. Survey, Monograph
25, 1895.
628 W. A. JOHNSTON
and that it overrode three prominent moraines which marked halts
or readvances of the ice front. Upham supposed that the Herman
beach represented the whole time of the formation of the several
moraines and of the retreat of the ice front for at least 250 miles,
in spite of the fact that he found the beach to be not very massive
and not very notably stronger in the southern than in the northern
portion. Recognizing this difficulty, Chamberlin suggested that
“the whole history of Lake Agassiz may not have fallen within the
period of stationary or rising crustal movement but that the early
part of it may have taken place during the latter portion of the period
within which the crust was being depressed.’* In this way it may
be supposed that shore lines were formed at early stages of the lake
but were later submerged. The uppermost Herman beach would
have been formed at the time of maximum submergence. It would
be all of one age and would represent a comparatively short time.
Another difficulty arises from the character of the deposits laid
down in the basin of the lake. Upham held that the greater part
of these deposits were derived from the ice sheet and its inclosed
drift—a necessary inference from his interpretation of the history
of the lake. But he found that ‘‘bowlders are absent or exceedingly
rare in the beaches, deltas, and finer lacustrine sediments.’? If it
is true that a series of moraines was deposited in the lake, and if
the sediments of the lake basin were largely derived from the ice
sheet, it seems highly probable that berg deposits would form an
important part and that bowlders would be included in the sedi-
ments.
A serious difficulty also arises if Upham’s interpretation of the
mode of origin of the sediments which occur in Red River valley
is accepted. Upham held that these sediments are recent fluvial
deposits laid down in local depressions and on flood plains of streams
after the disappearance of Lake Agassiz. The deposits, he states,
““have commonly greater thickness and extent than the underlying
silt of glacial Lake Agassiz.”’3 In the southern portion of the basin
they are in places underlain at considerable depths by ‘‘sheets of
turf,’’4 etc., apparently indicating the presence of an old soil. The
™ “The Glacial Lake Agassiz,” U.S. Geol. Survey, Monograph 25, p. 245.
2 Ibid., pp. 183 and 2o1. 3 Ibid., p. 202. bd pee
THE GENESIS OF LAKE AGASSIZ 629
great thickness and extent of these deposits and the occurrence of
“sheets of turf’’ in their lower portions seem difficult of explanation
on the assumption that they are ‘“‘recent fluvial deposits.”
All these difficulties disappear, however, if it is considered, as
the evidence seems to show, that Lake Agassiz had at first small
beginnings in Red River valley and gradually rose until it over-
flowed to the south, owing to a blocking of the northward drainage
by an advance of the ice, and that the ice advanced only into the
northern portion of the basin, so that the whole southern part of
the lake was practically free from ice during the entire existence
of the lake.
RECORDS OF LAKE AGASSIZ IN RAINY RIVER-LAKE OF THE WOODS
DISTRICT
Geographical relations of the district—The eastern portion of
Rainy River—Lake of the Woods district lies about midway between
Lake Superior and the Red River of the province of Manitoba.
The Rainy River connects Rainy Lake and Lake of the Woods and
for a distance of 82 miles forms the international boundary between
the state of Minnesota and the adjoining portion of the province
of Ontario. The Rainy River, the main stream of the region, flows
westward to Lake of the Woods, which drains northwestward to
Lake Winnipeg and thence to Hudson Bay, so that the whole area
lies within the Hudson Bay drainage system. ‘The altitude of
Rainy Lake is 1,107 feet and of Lake of the Woods 1,060 feet above
the sea, and the general altitude of the plain bordering the Red
River on the west is about 200 feet lower. The southern portion
of Lake of the Woods is shallow and is generally bordered by drift
deposits. The divide southwest of the lake, separating the lake
basin from that of the Red River on the west, is low and for some
distance is less than 30 feet above Lake of the Woods. On the
northwest, near Northwest Angle, the divide is also only a few
feet above the level of the lake, so that the plains of Manitoba and
northern Minnesota are practically continuous on the southwest
and northeast into the southern portion of the Lake of the Woods
basin. In southeastern Manitoba, and west of the southern portion
of Lake of the Woods, the continuity of the plain’s surface is broken
630 W. A. JOHNSTON
by a relatively high area which rises to a maximum height of about
200 feet above the general level of the plains. The area lying
between Rainy Lake and Lake of the Woods is so deeply drift-
covered that comparatively few solid-rock exposures occur. The
surface has generally very slight relief, and slopes gently toward
the west, so that the area really forms a portion of the eastward
extension of the wooded portion of the prairie plains of Manitoba
and northern Minnesota, from which it is separated by the shallow
basin of the southern portion of Lake of the Woods. In the north-
ern portion of Lake of the Woods and north ofa line drawn from the
central part of the lake southeastward to Rainy Lake, the country is
generally rocky and has comparatively little drift covering.
Till sheets —There are at least two distinct till sheets in the
district. The upper and younger is distinguished from the lower
and older till sheet by the calcareous nature of its materials, and
by the presence in it of bowlders of limestone and other rocks which
are known to outcrop in Manitoba, but not in the district itself
nor in the region lying to the northeast. Striae observed on the
bedrock beneath the till sheet trend southeastward or eastward.
These striae were not seen to be crossed by later striae, and no till
was seen to overlie this till sheet. It seems evident, therefore, that
the calcareous till was deposited by a lobe of the Keewatin glacier
and that the area in which the calcareous till occurs was not over-
ridden by an advance of ice from the northeast at a later time.
The lower and older till sheet was deposited by an ice sheet
advancing from the northeast. This is shown by the southwest-
ward trend of striae on the bedrock underlying this till sheet and
by the fact that the till contains no limestone similar to that which
occurs in the upper sheet. Associated with the lower till sheet are
considerable deposits of fluvio-glacial sands and gravels which also
contain no limestone. No evidence was seen which would suggest
that there was any considerable lapse of time between the depo-
sition of the two till sheets, and it is presumed that they were nearly
contemporaneous in age and were deposited during the Wisconsin
stage of glaciation.
Laminated stony clays.—A series of laminated clays, containing
in places striated stones and bowlders, occurs in the district. The
THE GENESIS OF LAKE AGASSIZ 631
clays overlie and in the eastern portion of the district also underlie
the calcareous till, with which they are closely associated. In some
sections there is a sort of transition upward from the unstratified
till into the laminated clays; that is, in the lower portion of the
clays distinct laminae of clay are separated by unstratified stony
material resembling the underlying till. The stony layers at the
base rarely exceed a few inches or at most a foot in thickness and
rapidly die out, so that “the transition beds” are, as a rule, only
4 or 5 feet thick. The laminated clays in the district range in
altitude from 1,060 up to at least 1,200 feet, but they are generally
only a few feet in thickness. These clays were deposited in a glacial
marginal lake which is here referred to as Early Lake Agassiz.
This lake was associated with an advance of the Keewatin glacier
which deposited the calcareous till in the region. The clays were
in part deposited during the time of advance of the ice sheet, for
in places till overlies the clays. This relation is well seen in the
sections exposed in the gravel pit one and one-half miles west of
Fort Frances, where 8 feet of calcareous till overlie laminated
clays, which are again underlain by non-calcareous, fluvio-glacial
sands and gravels. The laminated clays were also in part deposited
during the time of retreat of the ice. Early Lake Agassiz was,
however, largely if not wholly drained before the later Lake Agassiz
came into existence, for the desposits of Lake Agassiz rest uncon-
formably on the calcareous till and on the closely related laminated
clays.
Deposits of Lake Agassiz.—Numerous raised beaches of Lake
Agassiz occur in the district, at altitudes ranging from 1,100 to
1,200 feet. ‘The strongest and best-developed beach extends north-
ward for some distance from the vicinity of the town of Rainy
River. The altitude of this beach near the town of Rainy River is
1,117 feet. Ten miles northeast of this locality its altitude is about
1,125, and twenty-four miles northeast its altitude is about 1,140.
Higher beaches occur at various altitudes up to at least 1,200 feet.
A comparatively small part of the drift-covered area lying between
Rainy Lake and Lake of the Woods rises more than 1,200 feet, but
in the northern portion of Minnesota immediately south of Rainy
River district drift-covered areas rise considerably higher. In this
632 W. A. JOHNSTON
area a number of beaches rising well above 1,200 feet have been found
by Mr. Leverett, who states that bars of gravel and sand formed
by the waters of Lake Agassiz occur on the highest points of Bel-
trami [sland.*
The lacustrine deposits of Lake Agassiz in the district occupy
areas of considerable extent and are in places at least 30 feet thick.
They are generally even-bedded but not strongly laminated. In
places they are characterized by an irregular alternation of sandy
and clayey layers and occasionally thin gravelly layers. The
beds are in places more sandy toward their base than in their upper
portion, and are frequently ripple-marked but not cross-bedded.
The material is more oxidized than that of the older laminated
stony clays, and there can be little doubt that the material was
derived from erosion of land surfaces by wave and stream action.
The sandy ripple-marked beds underlying clay, and the occurrence
of gravelly layers interbedded with sandy and clayey layers are
explained by the fact that the sediments were deposited in a rising
body of water. The lacustrine beds are also characterized by the
presence, in their lower portions at least, of fossil fresh-water shells.
Fossil fresh-water shells also occur in some of the beach ridges at
various altitudes up to 1,149 feet, or 88 feet above Lake of the
Woods.
Unconformity at the base of Lake Agassiz sediments.—The evi-
dence found in Rainy River district, which confirms Tyrrell’s con-
tention that Lake Agassiz had at first a rising stage, is based largely
on the fact that the sediments deposited in Lake Agassiz rest
unconformably upon the underlying deposits; that is, a period of
erosion intervened after the deposition of the calcareous till and
associated laminated stony clay, and before the later lacustrine
sediments were laid down.
’ This is well shown in numerous sections exposed along the
Rainy River and around the shores of the southern portion of Lake
of the Woods. Fig. 1 illustrates the character of one of these
sections which has been exposed by wave erosion on the present
shore of Lake of the Woods at its southern side. At the base a
«Frank Leverett, “Surface Formations and Agricultural Conditions of North-
west Minnesota,” Minn. Geol. Soc., Bull. No. 12, 1915, p. 37.
THE GENESIS OF LAKE AGASSIZ 633
small thickness of calcareous till is exposed, passing up into lami-
nated, stony clay which is overlain unconformably by Lake Agassiz
lacustrine clays containing fresh-water shells. The contact is a
wave-cut plain. The lacustrine deposits above the wave-cut plain
are clayey in character and evenly and thinly bedded, so that it is
evident that the water must have risen to a considerable height to
permit of such deposition. In places around the southeastern
portion of Lake of the Woods these lacustrine deposits are at least
Fic. 1.—Section exposed on south shore of Lake of the Woods, showing at the
bottom calcareous till passing upward into laminated, stony clays unconformably
overlain by Lake Agassiz lacustrine clays. The contact is a wave-cut plain.
30 feet thick and rise to an altitude higher than the divide sepa-
rating the Lake of the Woods basin from that of the Red River on
the west. Furthermore, the first strong raised beach above the level
of Lake of the Woods, at the level of which the water must have
stood, if not at some higher level, when the lacustrine deposits were
laid down, is in the southern portion of the district from 45 to 55
feet above the level of Lake of the Woods; and this beach passes
over the divide to the southwest of the lake.t Hence it follows
that these lacustrine deposits were not laid down in a local lake
t Minn. Geol. Survey, Bull. No. 12, 1915 (map).
634 W. A. JOHNSTON
but in a body of water which covered not only the Rainy River
and Lake of the Woods districts but also occupied Red River valley,
and that this was the last great glacial-marginal lake in the region,
viz., Lake Agassiz. |
Numerous sections also show that weathering and erosion took
place during the interval of erosion before the deposition of Lake
Agassiz sediments. ‘This is well shown in sections along the Rainy
River from one to three miles below the town of Rainy River. In
places, small stream valleys were eroded and later partially or
wholly filled with lacustrine deposits. ‘This relation is well seen
in the small creek valley which enters the Rainy River three miles
below Fort Frances. In one place, on Buffalo Point on the south-
west side of Lake of the Woods, thin peaty bands occur in the lower
portion of Lake Agassiz deposits.
The sections exposed on the south shore of Lake of the Woods
(Fig. 1) afford a demonstration that the water must have risen to
a sufficient height to permit of the deposition of the fine lacustrine
clays overlying the old wave-cut beach, and it is clear that these
waters formed part of Lake Agassiz during a rising stage. There
is evidence in the district that the waters rose through a vertical
interval of at least 60 feet; for the lake clays are unconformable on
the underlying sediments throughout this vertical interval. The
highest shore line found in Rainy River district has an altitude of
1,200 feet. During the highest stages of the lake, practically the
entire district was submerged and the highest shore line, if there
had been land high enough to have received it, would have a present
altitude of approximately 1,350 feet, as estimated from Upham’s
determination of the highest beaches in other parts of the basin.
It is not certain that the water rose to the level of the highest shore
lines recognized in other portions of the basin; but it seems probable
that it rose to the uppermost strong beach (Herman), because this
beach, as already stated, is continuous for a long distance north-
ward and is apparently all of one age. It is possible that the
Milnor beach which Upham found to be traceable for only a short
distance in the southern part of the basin marks a shore line of
Early Lake Agassiz, but the extent of this lake or of any of its shore
lines is not definitely known. This lake was largely drained
THE GENESIS OF LAKE AGASSIZ 635
before Lake Agassiz came into existence and its sediments are
buried beneath those of Lake Agassiz.
It is at least certain that the waters of Lake Agassiz stood at
one time at about the present level of Lake of the Woods, and that
they later rose considerably higher. It seems probable also that
the lake which preceded Lake Agassiz was almost completely
drained, and that Red River valley was a land surface before the
latest advance of the ice brought Lake Agassiz into existence; for
the character of the deposits in Red River valley, which Upham‘
regarded as post-Lake Agassiz fluvial deposits, suggests rather
that they are lacustrine deposits and that they are unconformable
on the underlying sediments.
Regarding these deposits Upham stated:
Thus the occurrence of shells, rushes and sedges in these alluvial beds at
McCauleyville, Minnesota, 32 and 45 feet below the surface or about 7 and 20
feet below the level of Red River, of sheets of turf, many fragments of decaying
wood and a log a foot in diameter at Glyndon, Minnesota, 13 to 35 feet below
the surface, and numerous other observations of vegetation elsewhere along the
Red River valley in these beds, demonstrate that Lake Agassiz had been
drained away, and that the valley was a land surface subject to overflow by
the river at its stages of flood when these remains were deposited.?
He also stated: “‘The deposits have commonly greater thickness
and extent than the underlying silt of glacial Lake Agassiz.”
It is evident that a land surface existed in Red River valley
before these sediments were laid down; but it seems probable that
the sediments are largely lacustrine in origin and not fluvial.
G. M. Dawson, in describing the section across Red River valley
near the international boundary stated that the valley is floored
with a fine silty deposit, a portion of the upper layers of which may
have been formed by the overflow of the river itself. He described
the typical deposit as of great thickness and consisting of fine
yellowish, marly, and arenaceous clay, holding considerable cal-
careous matter, and effervescing freely with an acid. The great
extent and thickness and the high calcareous content of the clays
t Warren Upham, U.S. Geol. Survey, Monograph 25 (1895), p. 253-
2 [bid., p. 202.
3G. M. Dawson, Report on the Geology and Resources of the Region in the Vicinity
of the Forty-ninth Parallel, 1875, pp. 248-49.
636 W. A. JOHNSTON
would seem to show that they are lacustrine in origin and not fluvial.
It seems probable that they are Lake Agassiz deposits and that they
are unconformable upon the underlying sediments.
It is concluded, therefore, with Tyrrell, that after the retreat
of the Keewatin glacier well toward the north there was compara-
tively free drainage to the north and that a later advance of the ice
from the northeast was met by a slight readvance of the Keewatin
glacier, which resulted in the ponding of the northward drainage
and the inception of Lake Agassiz. It is not certain just how far
the latest advance of the ice extended. It did not reach Rainy
River district, for the calcareous till derived from Manitoba is not
overlain by till derived from the northeast, and the southeastward-
and eastward-bearing striae are not crossed by later striae. At
Stony Mountain, near Winnipeg, southeastward-bearing striae
cross striae trending nearly south, but are not themselves crossed
by later striae. Tyrrell found that along the east side of Lake
Winnipeg southwestward-bearing striae cross earlier striae bearing
nearly southward. ‘Tyrrell? also held that the “‘ Winnipeg Moraine”’
represented by islands in Lake Winnipeg and developed in places
along the western shore of the lake marked the termination of the
Labradorean glacier. It seems evident that during the life of the
last great glacial marginal lake of the region, viz., Lake Agassiz,
the ice margin in Manitoba was at no time farther south than the
southern portion of Lake Winnipeg, and that the whole southern
portion of the lake was practically free from ice. Lake Agassiz
was associated with a readvance of the ice sheet, chiefly of the
Labradorean glacier at a very late time during the Wisconsin stage
of glaciation, and its disappearance followed the final withdrawal of
ice sheets from the region.
BEARING OF THE LIFE-HISTORY OF LAKE AGASSIZ ON THE QUESTION
OF THE CHARACTER AND CAUSE OF THE DIFFERENTIAL
UPLIFT
If it is true, as seems probable, that during the existence of
Lake Agassiz the ice border was far north of the southern end of
the lake, this fact has an important bearing on the character and
tJ. B. Tyrrell, Amer. Geol., VIII, 21.
? Bull. Geol. Soc. Amer., XXIII (1911)
22
» #O0°
THE GENESIS OF LAKE AGASSIZ 637
cause of the differential uplift which is shown to have taken place
by the deformation of the shore lines of the lake.
It is known that the whole of the southern portion of the Lake
Agassiz basin was affected by uplift but that the region south of the
southern outlet of the lake was unaffected, for the abandoned shore
line of Lake Dakota in this region is apparently nearly horizontal.*
That is, there is a sort of ‘“‘hinge-line” here. The location of this
“‘hinge-line’’ was not due to “quick recovery of the crust by uplift”’
following removal of the ice from the immediate neighborhood, for
the ice border was at least 250 miles north of the location of the
“‘hinge-line.”’
The question also arises whether, as Chamberlin suggested, the
land was being depressed during the time of advance of the latest
ice sheet. It would be possible to determine this if the present
altitude with respect to sea-level of the beaches which were made
during the rising stage of the lake could be determined. It was
found in Rainy River district that the strongest beach of Lake
Agassiz apparently marks a long stand of the waters during the
rising stage and again during the subsiding stage; for the beach
deposits show evidence of having been partly eroded and spread out
by the rising waters and beach ridges having a slightly different
trend were later built on the older deposits. This would seem to
show that the land was already depressed during the rising stage -
of the lake, but the evidence is not very conclusive. In the case of
the ‘‘fossil’’ shore line seen in sections along the south shore of
Lake of the Woods (see Fig. 1), it was found that the beach main-
tains the same altitude in a direction corresponding to the trend of
the isobases of the beaches formed during the subsiding stage of
Lake Agassiz. It is not known whether it rises toward the north-
east, for unfortunately no record of its occurrence could be found
in the northern part of Lake of the Woods.
The evidence suggests, but does not prove, that if, as seems
probable, the uplift of the land was due to isostatic readjustment
following the removal of the burden of the ice sheets, there was no
close sympathetic relation; but that uplift lagged? considerably
* U.S. Geol. Survey, Monograph 25, p. 267.
2J. Le Conte, Bull. Geol. Soc. Amer., II (1891), 329-30; W. B. Wright, The
Quaternary Ice Age, 1914.
638 W. A. JOHNSTON
behind the removal of the great mass of the Wisconsin ice sheets
and was only completed after the final retreat following the latest
advance of the ice.
SUMMARY
Evidence bearing on the life-history of Lake Agassiz, found in
the Rainy River—Lake of the Woods district, Ontario, confirms
Tyrrell’s conclusion that Lake Agassiz had at first a rising stage.
The evidence is based largely on the fact that an unconformity
exists at the base of the Lake Agassiz lacustrine sediments. The
lake was associated with the latest advance of ice sheets, chiefly
of the Labradorean glacier, during the Wisconsin stage of glacia-
tion. An earlier glacial marginal lake, which is herein referred
to as Early Lake Agassiz, was associated with a lobe of the Kee-
watin glacier; but this lake was largely if not wholly drained before
Lake Agassiz came into existence. The latest advance of the ice
into the Lake Agassiz basin did not extend farther south than the
southern portion of Lake Winnipeg, so that the ice border of Lake
Agassiz was at least 250 miles north of the southern end of the lake
during the entire existence of the lake.
The acceptance of this interpretation of the genesis of Lake
Agassiz has an important bearing on the question of the character
and cause of the differential uplift which is shown to have affected
the region by the deformation of the shore lines. The evidence
suggests, but does not prove, that if the uplift was due to isostatic
readjustment following the removal of the burden of the ice sheets,
there was no close sympathetic relation, but that, as Le Conte and
Wright have supposed, uplift lagged considerably behind and was
only completed after the final retreat following the latest advance
of the ice sheets of the Wisconsin stage of glaciation.
THE LOWER EMBAR OF WYOMING AND ITS FAUNA
E. B. BRANSON
The University of Missouri
About ten years ago Mr. N. H. Brown sent me a few Helodus
teeth from the Embar limestone near Lander, Wyoming, and
in the summer of 1911 I had the good fortune to discover a rather
abundant fish fauna in the same region and on Bull Lake Creek.
In the former region the fossils occur about 25 feet from the bottom
of the formation and their vertical range is little more than 3 feet,
while in the latter they are found at from 35 to 38 feet from the
bottom.
Blackwelder? and Woodruff? have reported two distinct faunas
from the Embar, the upper of which Girty? refers to the Permian,
but the fauna reported here is older and entirely distinct from the
other two. Collections from bottom to top of the Embar in several
localities show only one species common to the fish horizon and the
upper horizons.
DESCRIPTION OF THE EMBAR LIMESTONE
The Embar formation lies conformably, for the most part,
below the Chugwater formation on the eastern slope of the Wind
River Mountains and without apparent unconformity above the
Tensleep sandstone. In the Big Popo Agie region, near Lander,
it is about 400 feet thick, is largely limestone, and bears three and
perhaps more phosphate beds. The lowest bed is 23 feet from the
bottom, ranges from 1 foot to 5 or 6 feet in thickness, and bears
fish remains and Orbiculoidea utahensis in abundance. This bed
has been traced some 15 miles southeastward along the strike and
about 5 miles nothwestward. I have examined the same bed on
t Eliot Blackwelder, “‘New or Little Known Paleozoic Faunas from Wyoming
and Idaho,” Am. Jour. Sci., XXXVI (1913), 177-79.
2E. G. Woodruff, “The Lander Oil Field,’ U.S. Geol. Surv., Bull. 452 (1913),
pp. 12-14.
3 Ibid., p. 13.
639
640 E. B. BRANSON
the North Fork of Little Wind River, 27 miles to the northwest,
and on Bull Lake Creek, 35 miles to the northwest. On Bull Lake
Creek it is 38 feet from the bottom and 3 feet 6 inches in thickness.
This is probably the same bed that Blackwelder describes as
occurring in Dinwoody Canyon 29 feet 8 inches from the bottom,
2 feet 2.5 inches thick, and containing Lingulodiscina utahensis.
Wherever the bed was examined it contained fish remains, and
Orbiculoidea utahensis in abundance.
In Big Popo Agie Canyon a 4-inch phosphate bed, as it was
measured, but probably much thicker, occurs 58 feet from the
bottom, and 6 miles southeast along the strike a bed 2 feet thick
occurs 54 feet from the bottom, and is followed 1o inches higher
by 14 inches of phosphatic shale. About 150 feet higher a
5-foot bed of gray phosphatic limestone is present in Big Popo
Agie Canyon, and 6 miles southeast along the strike a 5-foot bed
occurs at the same horizon. This is the bed that Blackwelder
describes as occurring 12 miles west of Lander—‘ Brownish-gray
odlitic and nodular phosphate rock full of Productus subhorridus
and other fossils (42.4 per cent tricalcium phosphate) ’’'—« feet
7 inches thick. This bed is readily distinguished from the lowest:
bed by its fauna. It contains Producti, spirifers, and Spiriferina
pulchra in abundance, while the lower bed contains none of these.
The Embar limestone is well exposed in Little Popo Agie Canyon
and the following description was worked out in 1913:
32. Greenish sandy shales and limestones: covered with talus and
with a bed outcropping here and there.................... 75’ to 100°
31. Light-gray, highly siliceous limestone with the silica in druses
as quartz and not as chert; this is the limestone that forms
long dip slopes on the east side of the Wind River M ountains. . C70 uae
go. Laght-gray, chenty lamestone). 225 -. 0 sc. ov leper San Buenaventura.....:...- 34 16 IIg 16 53-20
ZOSE ics Shin leiseliva seouomondaaoouns 33 43 118 17 58.61
200 heer Santa @atalina. jess seers 33 26 118 30 57-90
ASY Read ae Soledadeie se. racmnetiek cinitete 32 50 yar as 50.04
TOES Mona arbonse.-c icsacsic Settee 33 118 34 54.22
ASMea sack WilsonBeakoe em emac scl co 34 13 118 3 50.50
Aokis eaciac IospangelessNEWiaceimeeeicia: 33855 TiS 3 53-98
DEFLECTIONS IN PRIME VERTICAL (LONGITUDE)
Tian: PointeAnenaae eee 38 55 123 41 87.65
BN ee: Wklah aan cmv: Creesoirniors: 39 19 123 12 81.84
Gili fics INew, Presidio ie. -nei: 37 48 T2207 79.47
enor. Watayettesbarke eras er 37 48 T2226 80.34
taahoeeere Washington Square......... 37 48 £20)2'5 80.26
Osten IVE eELamoiltonere ee coer Diep Bi I2r 38 77.84
TO verse: IMianys valle aarp mistceeler ater: 39 8 1a BS, Tes
TOs eles Sacramentomar escent crate 38 35 I2I 30 75.07
2A0z eee Sans Diesoms 7a ee eee ieee 32 43 07 AO) 62.40
ZORA Wale phahoe sabia ci cia cei 38 57 IIQ 57 70.88
22tas eyer Verdin nie oomte alee iinet 39 31 119 59 66.21
ok ear Genoarcseace ec eee skein 30 IIg 51 71.66
DA sie sel Carson | Cltyap acces sek 39 I0 I1g 46 62.26
BG icra Virginia Cityenns eee era 39 19 IIQ 39 59.71
2T Orie. SangDiegon meee eaters 32 43 I17 9 63.69
BEM ie usr eve Los Angeles Normal Sch. oor. 34 3 118 15 61.52
DAB MW crane IBUENAVISCA jer eictaxc eke By 23 118 15 61.26
BOO Bonn ar WilsonPeakin: ssccn- cise ice 34 13 118 3 61.22
Ce rear Ware Ustad aeeieyreeieee 38 6 122 16 75.54
2OLe. aca Gazellen Serine we oie rece 4I 32 WA, Bat 75550
BOVPenere RUPE Cece) craps amiaeie ecient 44 4 TB RES ane
CHG Soh c Portland tiem ke eee ee 45 31 122 41 63.58
Aras dd tue MacCOmalsine Steere ecu ere ies 47 16 T2262", 57-98
SW ipaericne Seattlesmoqosime mm sarinsiee rer 47 40 122 19 57-79
Deine abe SeattlesaS8Seaenm eee eiac 47 37 122 20 58.77
Cho ae erty 2 iRonteRownsend are acer ae 48 7 122 45 60.71
Pas oor IBIEM Sac, diets aor wet uo 48 59 122 45 50.95
THE DOCTRINE OF ISOSTATIC COMPENSATION 707
TABLE I—Continued
Station No. Station Name Lat. (N.) Long. (W.) | eee
DEFLECTIONS IN PRIME VERTICAL (AZIMUTH)
Oh atte AXEOMM rans ata Uoietemt sapere: «cles Bomar 123 5TOu 7807
fhe edi he IMitewElelenaree (elena 2): 38 4o 122 38 le
Goes MiRamalpaisaie denne BU) iss 122 36 77-95
DL a ae UGRURGWEES es ooacdaconsade 34 55 I20 II 60.63
DOS Ss ane AT CUE OM ara eactersnsicmeaatrere nt 34 35 120 34 70.19
DIX Brae (CERO EE LY Bid a eae One ae Aenea 34 30 120 12 63.38
DONT] eRe News san Maguelt ene on 242 120 23 59.65
DAB. 4000 .6|| SHOUD Cobl4 Wigan ceooacesos 34 4 IIg 55 56.70
DPQ) o.0 oo 6 SantayBarbatasaies icici: 34 24 IIQ 43 58.71
BB Aral. Dominguez; Hull Soe a. 33 52 118 14 58.01
DADs suc o 0 SulphumeReakee eee meee 38 46 1) fit 66.37
DBs 50d 00 Ross Mountain............. 38 30 T2307, 72.48
DED 00500 Point Avisadero............ 37 44 I22 22 88.84
REO GS ote Monterey Baye eri) ise - 36 36 12 tS 89.46
Mil) 6 oom SamMtayO use ee seis y weer ave ive os 36 50 1D B TBA20
OANA AE ee ENSUE eee NG Ce REDE Bren aS 250 Tr 120 43 54.51
RDS s\a6- slo San Buenaventura.......... 34 16 IIg 16 52.50
D2 ree Santapleuclawmmyercre erie cree 36 9 nA DE 81.74
DON sic 6a ne Castle Mount.............. 35 56 I20 20 | 65.75
DOB 00808 EOS POM ACA eters area rao sla aness 34 54 120 36 71.71
STEP is Monticellonmacen se oes cece. 38 40 122 II 72.10
UT ae WiC ae ralstnacohre tere ctickess Giiersttenals 38 23 RAD & 74.89
egy a areas Nitta blo setrec cece senses 37 53 ioe OF 75.38
WAS Ses NolowNEWeBasehc (7. seo ssa 38 41 120 51 68.34
Digests Wolom Sha Baseran mccain se 38 32 12I 48 69.97
IEG? Gaal IMO COMMA is acid cscs cements 37 29 T2133 G7] 518i
TOMA oa INES DO eh enelglorc on Senueins of 39 206 I20 22 75-44
LO Mrs: oun Gd wROpeess swe verte 38 40 120 74.44
Die a WakeyMahoe Sls. cae a eee 38 58 IIQ 57 63.96
2 OR aeet IME, (COMME; os ooo cane 0e ds 37 58 IIQ 19 66.91
Rohe ede @arsomySinkw eye aac: se 30 35 118 14 60.49
DUS.o000¢ SantapAmale wncpsiecietrcioe sc 36 54 I2I 14 72.64
DOs \.0.0 a6 IVI OT ORME taurine mileRiaries 6 36 32 ATE BG) 78.97
22 Oty (fepsedanme We wi eevainc sce 36 19 120 49 65.71
ESTs a 22 Cape Henry Lighthouse (old) 36 56 7 Oma 52.72
LOM yse Vio ita sea Siecle urs 37 24 76 15 51.02
Sha artes 1B eli Kove Gard: cosets aCe are etna 33 118 34 72.60
GAR eee s Snow Mountain F........... Bons 122 45 81.50
BEG siete om Marysville Butte............ 39:12 I2I 49 82.51
BOO sicronee Vit Gramtertry ae cnn sce cise: 38 34 118 47 61.80
iets iat RGU Hie Sti Cie aol pha cere es creioie 39 58 122 44 81.52
BGO ial aves TEV OMS WME Lette ane eles ia ts 4o 18 I2t 38 77.35
BGO seco: VO UITG Me Ree SES crater ee a a 40 48 Tepe 7) 77.95
GOA Soave IRIS tp en CNS eae Gra oaeueet Aas 42 37 122 21 75.00
BOB RR s: COMTOTING Re erat onl alee te cuaracs 42 4I 123 14 85.05
BOAB ee SCO tEAUY Mee nari ee rey osholre nist L 43 22 1234 85.76
BOSi ads as SPENCeliesceascaache ele cases 43 59 123 6 81.06
BOGmr esa IMENT) AN es ear etn Mea daieais 44 30 T2282 76.64
As oo5 on PYCa TIT Rapanui sree rebates bey auc re tela! AST, 13" G) 76.15
BOs es IB ATIVES HE ae whereas ctsceoresioerecn ets 45 32 122 45 63.31
708 WILLIAM HERBERT HOBBS
TABLE I—Continued
DEFLECTIONS IN PRIME VERTICAL (AZIMUTH)—Continued
Station No. Station Name Lat. (N.) Long. (W.) (Cen
BUT eee axe Balch yo yeaccec pes cee Sect AB ao! 122°43' 63770
BIS sais cays WAU oy yess ss eicto ote eocre inet 46. 8 122 28 68.56
BTA acs BGLAL .tale aranayeraiet orevensie easiest ae 46 47 I21 56 59.78
BVO cies Roint Eridsone pene ecieet: Agey T2 2A 66.69
Bella aod Classet acme cera tric Geer tae 48 23 124,40 52.32
BOOM ae BeechyPread i 2,2.2,.)ccreie crete 48 20 123 39 56.69
located in the Atlantic Coast province (see below, p. 711), all are
to be found within the intense seismic area of the Pacific coastal
region, which was so recently, after the destructive California
earthquake of 1906, the subject of special investigation. When
now the stations showing notable anomaly are accurately plotted
upon the special map of the seismic province prepared by the
Earthquake Investigation Committee,’ it at once appears that there
is an apparent relationship between their distribution and that of
the better-known recent faults of the province. The number of
stations with corrected anomaly of deflection greater than 50” is
something more than half (58 per cent) of the total number of
stations within the Pacific Coast province. In the map of Fig. 1
which shows the distribution of the abnormal stations (in dotted
outlines the map of the Earthquake Investigation Committee)
black circles of different diameters have been used to bring out
roughly the magnitude of the corrected residuals, and it appears
that those of higher order particularly are generally grouped near
the known displacements of the district, some of which have been
the seats of movement during recent earthquakes.”
Distribution of residuals in excess of 35" of arc—Had the mini-
mum of abnormality of deflection been made 35” of arc, instead of
t A. C. Lawson, G. K. Gilbert, H. F. Reid, J. C. Branner, A. O. Leuschner, George
Davidson, Charles Burckhalter, and W. W. Campbell, Atlas of Maps and Seismograms
accompanying the Report of the State Earthquake Investigation Committee upon the
California Earthquake of April 18, 1906 (Carnegie Institution of Washington, 1908),
Map tf.
2 The recent faults are not indicated on the area outside the dotted border. Few
gravity data relatively are available for the area east of California, where many fault
lines are shown.
THE DOCTRINE OF ISOSTATIC COMPENSATION 709
50”, practically all of the remaining stations located within the
California earthquake province would have been included, and a
‘separate group would have been found within the Atlantic coastal
710 WILLIAM HERBERT HOBBS
province (Hayford’s northeastern and southeastern groups of
stations). This supplementary list prepared upon the basis of a
minimum of abnormality of 35’’ of arc, but without including the
additional Pacific slope stations, is given in Table II, following.
The stations listed in this table have been plotted and appear in
the map of Fig.2 with some indication of the measure of abnormality,
and upon the map of Fig. 3 are found the points of higher seismicity
as determined by De Montessus upon the basis of recorded data,t
which, however, of necessity give undue prominence to localities
of early settlement or of later importance commercially.
General conclusion as to law of distribution of anomaly of gravity.—
Hayford’s own observations thus confirm the evidence derived from
other regions that anomaly of deflection of the vertical and of
gravity show large local defect or excess, and that these local
anomalies are in some way connected with the distribution of seis-
micity and with zones of dislocation.2, We believe therefore that
the late Professor de Lapparent was correct when in 1903 he stated
with much force before the French Academy:
I believe, therefore, that for the present we may claim that the sea upon
the one hand, and the continents upon the other, enter into the variations of
gravity there only where a dislocation puts into contact two crustal compart-
ments, one of which is depressed and one of which remains stationary or is
One may add that even in countries where the surface does not reveal the
dislocations, a means is found for diagnosing the deep and hidden faults.
Finally, the relation of seismic regions to rapid variations in the anomaly of
gravity shows that it would be eminently proper to carry out such studies in
order to make known those provinces of our globe which have most to reckon
with the danger from earthquakes [translation].3
May not the truth, as in so many other controverted ques-
tions, lie between the extreme viewpoints ? It is possible to assume
Count F. de Montessus de Ballore, ‘‘Les Etats Unis séismiques,”’ Archives des
Sciences Physiques et Naturelles de Généve, 4th period, V (1898), 201-16. See also
William H. Hobbs, ‘‘On Some Principles of Seismic Geology,” Gerlands Beitrége zur
Geophysik, VIII (1907), Appendix, pp. 289-92, Pl. 2; also, Earthquakes (Appleton,
1907), pp. 112-16.
2 While magnetic data are available for the territory of the United States (United
States Magnetic Tables and Magnetic Charts for 1905 [Washington, 1908]), their dis-
cussion by Bauer is still unpublished, and it would be premature to discuss them here.
3M. A. de Lapparent, op. cit., pp. 830-31.
THE DOCTRINE OF ISOSTATIC COMPENSATION
TABLE II
fae
““ABNORMAL”’ DEFLECTIONS OF THE VERTICAL—HAYFORD (CORRECTED FOR
TopoGRAPHY) (Minimum, 35” oF ARC)
Station No.
eee eee
eee eee
eee eee
eee eee
eee ees
eee eee
eee eee
eee eee
eee eee
eee eee
eee eae
eee eee
Station Name
DEFLECTIONS IN MERIDIAN
Lat. (N.) | Long. (W.)
7523,
74 43
67 24
67 17
Te) (©)
78 31
78 22
77 4
AV/E10 ls i RR Mee 39°58’
IVINOSC Ratan tans tee 4O 22
TO WAT ee st Slee Sor a Re 44 38
Calaisperr eee stem ae 45 11
JNO) Og3i 03 ore ue etala Cae NE rene 4I 17
DEFLECTIONS IN PRIME VERTICAL (LONGITUDE)
Charlottesville.............. 38 2
Strasbun gee secre pi tosese cya ce 38 59
Naval Observatory.......... 38 55
Naval Observatory.......... 38 54
C. and G.S. Observatory..... 38 53
IDONRs.6 5S GS SRS oe 30 9
Caper Mayen ra. wena are erates 38 506
ROS] yatoen sen cwsrueparere cise cues 5 aay ail
Staumtomees gets ce. clo cis oc ehtane 38 9
Scatonpre eer eo aes: 38 53
Statesvalle ys ess coos ha 35 47
Cambridcemenneeeeroeeen ok A221)
ID) OB OOO 7S Gi ney cee ale aioe eee eee 9) B
BAT COR Me mrcaeue poe fie once: 44 48
Calaiswr eee ee eee roo: 45 11
Provincetown aso. AP @
TRIE SEAS U AICI LER Me ae pine tris aN 4I 30
MIE, WERE. CS So eooeoolbeds 390 4
Chad eR Sennen a nee 38 I9
onge Mount yee sie ece Bop ath)
BulliRune Becker ecacle a 38 53
Maryland Heights.......... 39 20
Sucarloaicae Meine wetacuee 39 16
aus tems ean ates clsteuneee as 38 50
Caperklenlopentne ae ae 38 47
Capevblenty ite soars es 36 506
Knott Island, North End..... 36 34
NVioltitrap aici ets citan er erate 37 24
Mangiersisland! j.5 se se ede a: 37 48
INTO OTE ee isbaos an syaslnraete ois & 36 24
IKGiTT EPA aa EN rvtM epta ahs a BIS 503)
Wiad sired etn ciao aernelcyy ease 39 58
IMItESIROSE Ios sey pt ees re eens 40 22
Bea compbil eas mere ine ac 40 22
Cambridzennereieen eee: 42 23
Deflection
(Corrected)
a2 WILLIAM HERBERT HOBBS
TABLE Il—Continued
Station No. Station Name | Lat. (N.) | Long. (W.) Fomieeee:
DEFLECTIONS IN PRIME VERTICAL (ASIMUTH)—Continued
DAQM teens Spencers .shee ee on oa 41°41’ Tpit ley 45730
TOM ae iBeaconpolessee te eee eer 42 His PA 43.38
TS Biecrceiers COPE CU ea sa ere echt Royals, oe AI 43 Gis ae 40.10
TGS re reher: AGaYGHED) nyn eee ge leet Aastra te Been 4I 26 70 AI 46.49
BETCHA fo ttl Shooting namaste 4I 41 70 21 37-97
TIS aes re Ble aL ae ee ee eens oa AG} 0B 77 41.90
DS Orestes < Ab IN eo dasaocoucodnd 42 37 70 44 40.35
ESO niet Wnkonoonucsee eer seer erieae 42 50 7G 37.98
TORS Oke Acamenticuse. see soeeeeeee 43 13 70 42 41.42
Dai ar es DAVIS Wecsyek sshetticis Mcueet tai 38 20 TiO 48.87
DA Shei MG Bluesith) Jie. dete vee 44 44 70 31 Beals
ry loner ene Gardiners Island .225-..- 0: Ar 6 AO 37.42
DIGGIN cae Bamegatenlets aeaqcecaaecere ck 39 46 74 6 40.78
OLS. & dow & Cahash eed nse eeter BG 80 1 38.07
SR OM Rae Chapels perme 40 24 74 4 44.23
BOR eter Sankatysbleadraennrseere tir AE 17 69 58 Bayt
evils, S Algor Hi gheRointeeenyaeerenet 4I 19 74 40 40.99
3 SiS pantera Wiomelsdoriarr sericea 40 19 76 12 40.98
that a tendency to attain to isostatic adjustment exists within the
earth’s outer shell as a consequence of diastrophic action, and that
at any given time large areas, such as the greater portion of the
United States, are measurably compensated. In areas more re-
cently disturbed and at a more rapid rate (western section of the
United States or the Himalaya region), which still betray their
lack of stability in earthquakes, no such state of isostatic compen-
sation can be postulated. Such regions show a rigidity sufficient
to support their excessive loads for long periods even if measured
in geological units, and if they yield to some extent through eventual
fatigue of the materials under strain, this effect lags far behind the
degrading effects of surface erosion and transportation. Some sug-
gestion of this idea appears to be found in the paper by Crosthwait.*
CRITICISM OF HECKER’S DETERMINATIONS OF GRAVITY OVER THE
OPEN SEA
Helmert’s claim that gravity is nearly constant over deep water of
the ocean.—A line of evidence which has been held to support the
conception of isostatic compensation, but for the oceanic areas
z Op. Cit., Pp. 4-5.
THE DOCTRINE OF ISOSTATIC COMPENSATION 713
only, is that supplied by Helmert and Hecker, who have applied
the Mohn hypsometer-barometer to measurements of gravity over
the opensea. Upon the basis of these studies, which were executed
ALE eee
Coes
714 WILLIAM HERBERT HOBBS
by Hecker, Helmert has claimed that ‘‘the force of gravity above
the deep water of the Atlantic Ocean between Lisbon and Bahia
is nearly normal’’—that is to say, the same as at the shore within
Vie
i
CP
THE DOCTRINE OF ISOSTATIC COMPENSATION 715
the same latitude.t If this statement is well founded, it would be
difficult to escape the conclusion that at least partial compensation
exists for the oceanic areas. But from examination of the figures
in Hecker’s original monograph,’ a different form of statement would
seem better to express the facts. Up to the time of Hecker’s
Atlantic voyage geodesists, through basing their conclusions upon
pendulum observations made upon a few oceanic islands, had held
the belief that gravity is uniformly in excess over the oceans; and
the force of Helmert’s statement lay in the fact that it exploded
this notion, which had received official sanction from an interna-
tional geodetic congress. \ WHERE DUPLICATE COPIESARENEEDED
- Daus Improved Tip Top Duplicator
From the Cambridge University Press
THE GENUS IRIS
By WILLIAM RICKATSON DYKES
With 48 colored plates and 30
line drawings in the text
This magnificent work brings together the avail-
able information on all known species of Iris. The
- most striking feature of the book is the life-size colored
plates, reproduced from originals drawn from living
_ plants—making it a volume of remarkable beauty as
well as of great scientific importance.
254 pages, demi folio, half morocco; price $37.59,
postage extra (weight rr Ibs.).
The University of Chicago Press
5758 Ellis Avenue, Chicago, Illinois
is an ideal assistant, always ready to reproduce clean, clear,
perfect copies of letters, manuscripts, price lists, bills, in-
voices, reports, drawings, menus, etc., etc.. Don’t take
our word, try it yourself for
Ten days’ trial without deposit
If not satisfactory, return and no questions asked. Makes
150 handwritten and 50 typewritten copies in a few min-
utes. Negatives require no washing out after using, and
negative rolls can be used from 15 to 20 times. Complete
outfit contains a continuous roll of Daus Non-Peeling Anti-
Stick Negative Roll. Capsize,8}x13inches. Price $7.50
FELIX K. DAUS DUPLICATOR CO.
Daus Building, 111 John Street, NEW YORK
TEACHERS
OF
BIOLOGY AND GEOLOGY
Will find the Bulletins of the Geo-
graphic Society of Chicago of special
value for field trips, lectures, etc.
Write for descriptive circulars. a
The University of Chicago Press
Chicago - - - - Illinois
(Sr eS
BUY
“ON EXAMINATION”
THAT MEANS
‘* Test and try before you buy’’
- Remington Junior Typewriter
Remington Quality; Remington Workmanship
Remington Guaranty
Produced purposely to supply the demand for a high-
grade but low-priced writing machine for the home,
the farm, the store, the office and the study.
Cut out and post today
REMINGTON TYPEWRITER COMPANY
(Incorporated)
327 Broadway, New York
Send me a Remington Junior Typewriter, price $50,
on free examination. It is understood that I may re-
turn the machine, if I choose, within ten days. If I
decide to purchase it, I agree to pay for it in ro
monthly payments of $5 each.
Do You Want to Know
What Your Handwriting
Reveals?
WE have published a fascinating
booklet of 32 pages on the sub-
ject of graphology, by William Leslie
French. Every reader of this publi-
cation will be interested in comparing
the examples of handwriting in judg-
ing character and disposition of the
writer.
A copy of this booklet and 12 differ-
ent patterns of The Spencerian
Steel Pens will be sent postpaid on
receipt of ten cents.
If you can do good work with a poor pen
you can do better work with a good pen.
Silver plated Falcon pens, smooth points,
wear long, will not corrode.
SPENCERIAN PEN CO.
349 Broadway - . - New York City
Widely Recognized as
Superior Instruments
Their general use by leading educational institu-
tions, both great and small, and by eminent
microscopists and scientists, is acknowledgment of
the superiority of
B ancch lal
Microscopes
The hard, steady use of classroom and laboratory
emphasizes their durable mechanical construction,
their extreme optical precision, and their practica-
bility. Models vary from simple form to wonder-
fully precise compound instruments.
Model FS2 (illustrated) is unusually well adapted
for educational use, having sensitive, fine adjust-
ment combined with curved handle-arm which
allows ample space for object manipulation. Fin-
ished in our new black crystal, reagent proof and
more durable than ordinary lacquer. Price $34.00.
Simple Microscopes $2.50 up. Compound Models,
$18.00 up. Special terms to Educational Institu-
tions.
White for descriptive catalogs, giving illustrations
and prices of all models.
Bausch £9 lomb Optical ©.
412 ST. PAUL STREET ROCHESTER, N.Y.
New York Washington Chicago San Francisco
Leading American Makers of Photographic Lenses, Binoculars,
Fraeciee Lanterns (Balopticons) and other high-grade optical _
products. P
NUMBER 8
THE
2NAL or GEOLOGY
EDITED BY
With the Active Collaboration of
ser0W" Vertebrate Paleontology ALBERT JOHANNSEN, Petrology
, Invertebrate Paleontology ROLLIN T. CHAMBERLIN, Dynamic Geology
ALBERT D,. BROKAW, Economic Geology
ASSOCIATE EDITORS
Great Britain JOSEPH P.IDDINGS, Washington, D. G.
JOHN C. BRANNER, Leland Stanford Junior University
RIGHARD A. F. PENROSE, Jr., Philadelphia, Pa.
WILLIAM B. CLARK, Johns Hopkins University
WILLIAM H. HOBBS, University of Michigan
_ FRANK D. ADAMS, McGill University
CHARLES K. LEITH, University of Wisconsin
WALLACE W. ATWOOD, Harvard University
- WILLIAM H. EMMONS, University of Minnesota
ARTHUR L. DAY, Carnegie Institution
DAVID, ‘Australia
. Leland Stanford Junior University
BERT, Washington, D.C. !
i: LCOTT, Smithsonian mstaturion
mell Urey
~ NOVEMBER- -DECEMBER 1916
OLE “OF ~ ANORGANIC AGENCIES ‘IN THE DEPOSITION OF CALCIUM
- - JoHN JOHNSTON AND E. D. WILLIAMSON = 729
IE STRUCTURAL “RELATIONS ae AUSTRALASL NEW GUINEA, AND
- E. C. ANDREWS. 751
TERION OF THE ANTIQUITY OF THE ANGIOSPERMS
EpMUND W.SINNOTT 777
eo.
Bay , ATHOLITHS” OF THE HALIBURTON-BANCROFT AREA, ONTARIO,
RECTLY NAMED? ~— - : »< op) Ll “FRancis M. VAN Tuyt ~ 792
‘S OF CAPILLARITY ON OIL ACCUMULATION _. A.W. McCoy 798
PROCESS OF SULPHUR DEPOSITION- - _ = -¥, Omovve- 806
TUDE ENTS: CO TO THE STUDY OF RIPPLE MARKS
é Doucias W. JoHNson 809
iy
1
H
NT PU CATIONS
OUNE XXIV
spy tests DBS
oa E UNIVERSITY OF GHIC AGO PRESS
sd <°“ CHICAGO, ILLINOIS, U.S-A:
AGENTS
"THE CAMBRIDGE UNIVERSITY PRESS, Lonpon ANP
access KARL W. HIERSEMANN, Leipzic
THE en 2008 Toxyo, OSAKA, Kyoto, FUKUOKA, SENDA!
THE MISSION BOOK COMPANY, SHANGHAI
EDINBURGH
THE JOURNAL OF GEOLOGY
EDITED BY
THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY -
With the Active Collaboration of f
SAMUEL W. WILLISTON ALBERT JOHANNSEN
Vertebrate Paleontology Petrology
STUART WELLER ROLLIN T. CHAMBERLIN
Invertebrate Paleontology Dynamic Geology
ALBERT D. BROKAW
Economic Geology
The Journal of Geology is published by the University of Chicago at the University Press semi-
quarterly, on or about the following dates: February 1, March 15, May I, June 15, August 1, September 15,
November 1, December 15. {] The subscription price is $4.00 per year; the price of single copies is
65 cents. Orders for service of less than a half-year will be charged at the single-copy rate. {| Postage is
prepaid by the publishers on all orders from the United States, Mexico, Cuba, Porto Rico, Panama Canal
Zone, Republic of Panama, Hawaiian Islands, Philippine Islands, Guam, Samoan Islands, Shanghai.
4] Postage is charged extra as follows: For Canada, 30 cents on annual subscriptions (total $4.30), on
single copies, 4 cents (total 69 cents); for all other countries in the Postal] Union, 53 cents on annual
subscriptions (total $4.53), on single copies, I1 cents (total 76 cents). J Patrons are requested to make
all remittances payable to the University of Chicago Press in postal or express money orders or bank
drafts.
The following agents have been appointed and are authorized to quote the prices indicated:
For the British Empire: The Cambridge University Press, Fetter Lane, London, E.C. Yearly —
subscriptions, including postage, 18s. 8d, each; single copies, including postage, 35. 2d. each.
For the continent of Europe: Karl W. Hiersemann, Ko6nigstrasse 29, Leipzig, Germany. Yearly
subscriptions, including postage, M. 22.65 each; single copies, including postage, M. 3.80 each.
For Japan and Korea: The Maruzen-Kabushiki-Kaisha, 11 to 16 Nihonbashi Tori Sanchome,
Tokyo, Japan. Yearly subscriptions, including postage, Yen 9.00 each; single copies, including
postage, Yen 1.50 each.
For China: The Mission Book ‘Company, 18 Peking Road, Shanghai. Yearly subscriptions,
$4.00; single copies, 65 cents, or their equivalents in Chinese money. Postage extra, if mailed direct
outside of Shanghai, on yearly subscriptions 53 cents, on single copies II cents.
Claims for missing numbers should be made within the month following the regular month of
publication. The publishers expect to supply missing numbers free only when they have been lost in .
transit.
Business correspondence should be addressed to The University of Chicago Press, Chicago, III.
Communications for the editors and manuscripts should be addressed to the Editors of THE
JOURNAL OF GEOLOGY, the University of Chicago, Chicago, Ill.
Contributors are requested to write scientific and proper names with particular care and in citations
to follow the form shown in the pages of the Journal. .
Separates, if desired, must be ordered in advance of publication.: Separates of leading articles will We
printed as ordered, of which 50 (without covers) will be furnished gratis, the actual cost of the vena
(and covers, if desired) to be paid for by the author. The actual cost may vary, and will depend upon
the amount of work in re-making the pages into forms, presswork, paper, binding, etc. Separates
containing half-tones may be expected to cost somewhat more, the increase depending upon the number
of cuts and the amount of work required upon them.
Entered as second-class matter, March 20, 1893, at the Post-office at Chicago, II]., under the Act of March 3, 1879.
VOLUME XXIV NUMBER 8
THE
lOWRNAL OF GEOLOGY
NOVEMBER-DECEMBER 1916
THE ROLE OF INORGANIC AGENCIES IN THE DEPOSI-
TION OF CALCIUM CARBONATE
JOHN JOHNSTON anv E. D. WILLIAMSON
Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C.
Organic agencies are doubtless the predominant occasion of the
deposition of calcium carbonate, yet certain inorganic factors may
not safely be left out of account. The mode of action of the former,
which is in part a biological question, we shall not enter into, but
we shall limit ourselves to a discussion of the effects producible by
variation of certain inorganic factors which affect directly the solu-
bility of calctum carbonate. The question of the concentration of
calcium relative to the limiting saturation concentration of calcium
carbonate under the particular conditions—in other words, the rela-
tive degree of saturation with respect to calcium carbonate—has not
received adequate consideration; this is largely the consequence of
faulty data and of contradictory and erroneous statements regarding
the solubility of calclum carbonate under various conditions. It is
our purpose to direct attention to the quantitative effect, as deduced
from laboratory study, producible by variation of those factors
which, by affecting directly the degree of solubility of calcium car-
bonate, induce its precipitation from a solution saturated with it;
and to emphasize the fact that many of the points now ambiguous
may be settled by means of systematic and accurate investigation
Vol. XXIV, No. 8 720
730 JOHN JOHNSTON AND E. D. WILLIAMSON
of a certain group of properties of sea-water, properties which, more-
over, are of high importance in connection with certain biological
problems. The mode of treatment is similar to that employed by
Stieglitz,t who, at the instance of Chamberlin, carried out series of
calculations to ascertain the proportion of CaCO, which one might
expect to find in gypsum that had been deposited from solutions
saturated with respect to both CaSO, and CaCO, at different partial
pressures of CO, in the atmosphere in contact with the solution.
The principles, therefore, are not new, though the point of view
differs somewhat; and we now have the advantage of more extensive
data than were available in 1907.
The data bearing on the solubility of pure calcite have been col-
lated and discussed at length in two recent papers,? to which the
reader desirous of fuller information on the chemical side is referred.
As it would lead too far to discuss here all details of the solubility-
product constant and of its mode of calculation, we shall give only
the established conclusions which are pertinent to the present dis-
cussion, premising that a symbol inclosed within brackets represents
the concentration (expressed in moles per liter) of that particular
ionic or molecular species.
1. Inasolution at a fixed temperature saturated with pure calcite,
the solubility-product—i.e. [Catt] [CO], the product of the respec-
tive concentrations of calcium-ion and carbonate-ion—is a constant,
independent of the proportion of free CO, in the solution and of the
presence of other salts. This characteristic solubility-product con-
stant is to be carefully distinguished from the solubility which, as
ordinarily measured, is the concentration of total calcium in a solu-
tion in equilibrium with solid calcite; and this calcium is associated
with bicarbonate and hydroxide (and with any other anion present,
e.g., chloride or sulphate) as well as with carbonate—indeed, under
ordinary atmospheric conditions but a small fraction of the total
tJ. Stieglitz, ‘The Relations of Equilibrium between the Carbon Dioxide of the
Atmosphere and the Calcium Sulphate, Calcium Carbonate, and Calcium Bicarbonate
in Water Solutions in Contact with It,” in ‘‘The Tidal and Other Problems,” by
T. C. Chamberlin et al., Carnegie Inst. Publ. No. 107 (1909).
2J. Johnston, Jour. Am. Chem. Soc., XXXVII (1915), 2001, hereinafter desig-
nated for convenience as op. cit.; Johnston and Williamson, ibid., XXXVIITI
(1916), 975.
AGENCIES IN DEPOSITION OF CALCIUM CARBONATE 731
calcium is ever associated with carbonate. The fact of the con-
stancy of this solubility-product in presence of solid calcitet enables
us to calculate, with all the accuracy required for the purposes of
this paper, the solubility of calcite under any specified conditions,
e.g., in presence of calcium-ion or carbonate-ion from whatever
source derived, provided only that we can ascertain what these
ionic concentrations actually are.
2. The concentration of H,CO, (‘“‘free” CO,)in solution is regu-
lated by the partial pressure (P) or proportion of CO, in the layer
of atmosphere in contact with the solution, and conversely; and,
for a given value of P, it diminishes with rising temperature, since
the absorption coefficient (solubility) of CO, diminishes.
_3. Ata given temperature the total solubility as usually measured
—1.e., the total concentration of calcium in the solution—varies with
the concentration of H,CO, (hence with P), owing to the fact that
the latter determines the proportion of carbonate-ion COj,
hydrocarbonate-ion HCO7, and hydroxide-ion OH™ in accordance
with definite mathematical expressions; and since the product
[Cat*] [CO] remains constant [Ca**] must vary inversely as [CO§].
The presence of other salts also affects this total solubility; so long
as pure calcite is the stable solid phase in equilibrium with the
solution, the magnitude of this effect is readily calculable, since the
several concentrations always adjust themselves until the solubility-
product [Cat*] [CO%] attains its characteristic value.
4. The solubility-product constant of calcite diminishes with
rising temperature; it is not affected to an appreciable extent by
change of hydrostatic pressure. |
The mathematical expressions are given below:
[H.CO,]=cP
[Cat : [CO>|= XK. (in presence of solid calcite)
[HCOs}/[CO>]=/[H.CO,] =lcP
[OH—}?/[COF]=m/|[H.CO,]=m/cP
where c, K,,/, and m are constants at any given temperature.? We
may note, moreover, that the free CO, and the total CO, (ie.,
‘Similar remarks apply, mutatis mutandis, to impure calcite or to aragonite;
to this point we revert later.
2 For their values and significance, see Johnston, of. cit., p. 2011.
732 JOHN JOHNSTON AND E. D. WILLIAMSON
[H,CO,]+-[CO ;]+[HCO7]) determine [OH™], the degree of alkalinity
(or acidity) of the solution; and that no change can be made in any
one of these quantities without affecting each of the others.
Accordingly the solubility of calcite is significant only if the con-
centration of free CO, is controlled and measured, for changes in the
latter, such as may easily occur, exert a large influence on the amount
dissolved.t' This is evident from Table I, which gives the solubility
TABLE I
SOLUBILITY OF CALCITE AT 16° FOR VARIOUS VALUES OF P
CO, IN THE ATMOSPHERE EXPRESSED
FREE CO; or SOLUBILITY OF
Bet INSOLUTION, ae Parts:
As Partial _|As Parts per 10,000 SASS aCO; PER
Pressure P (by Valimes MILLION MILLION
0.0001 TO 0.18 44
- 0002 2.0 * 360 55
-00025 2.5 -45 59
- 0003 3.0 55 6 3
00035 Bub 64 , 66
©.0005 aie) 0.90 75
at 16° for various values of P not far removed from the proportion
normally present in the atmosphere (about 3 parts per 10,000).
Calculation shows that except for very small partial pressures of
CO, the calcium in solution is associated almost entirely with
bicarbonate—thus even when P is only 0.0005, the proportion as
carbonate is only about 2 per cent, whereas when P is 1.0, the pro-
portion is less than 1 part in 30,000; nevertheless, carbonate is still
the solid phase which separates out, an excellent example of the fact
that it is the solubility relations and not the “affinity” relations in
solution that determine which of the possible stable solid phases
shall appear.
t Neglect of this factor or, in general, a failure to secure equilibrium conditions
is responsible for erroneous statements in the literature. For instance, the solubility
as given by Treadwell and Reuter (Z. anorg. Chem., XVII [1898], 170) is not a real
solubility at all; acceptance of their figure (238 parts per million) has led several
writers astray. Cf. op. cit., p. 2009. Thus on this basis J. C. Jones (Science, XX
[1914], 829) concluded that the waters of the Lake Lahontan basin are only about
one-twentieth saturated with CaCO.
AGENCIES IN DEPOSITION OF CALCIUM CARBONATE 733
The change of solubility with temperature, the proportion of
CO, being constant, is evident from Table II, which contains values
interpolated from the curve expressing the observations by Wells,
as well as the molar absorption-coefficient (c) of CO, and the calcu-
lated value (K¢) at each temperature. There is a slight error
involved in identifying KZ with the solubility-product constant
[Cat*] [CO%] except at temperatures close to 18°, because in calcu-
lating K; we have—for lack of better knowledge—assumed that the
ratio (mr) of the first to the second ionization-constant of H,CO, is
independent of the temperature; nevertheless, since these values of
Ko were obtained from actual measurements of solubility, they
enable one to calculate? for any temperature up to 30° the solubility
of calcite under any conditions of CO, pressure or salt-concentration.3
TABLE II
THE SOLUBILITY OF CALCITE UNDER ATMOSPHERIC CONDITIONS
(P=0.00032), AND THE SOLUBILITY-PRODUCT CONSTANT
AT SEVERAL TEMPERATURES
Temperature Solubility ot Calcite eens Solubility, treduct
: per Million ee Ki,Xro!
fo) 81 0.0765 1 9}
5 75 .0637 1.14
Io 70 -0535 1.06
15 65 0455 0.99
20 60 .0392 0.93
25 56 .0338 0.87
30 52 0.0297 0.81
From the foregoing it follows that in order to decide definitely
if a natural water is saturated with respect to calcite one must know:
(a) the concentration of free CO, in the water, (6) the temperature,
(c) the concentrations of the other constituents present. Of these
the third is the only one which has in general: been satisfactorily
ascertained, but it is only of subsidiary importance; experimental
data on the two important factors are commonly either lacking or
™R. C. Wells, Jour. Wash. Acad. Sci., V (1915), 617.
2 For the mode of calculation see Johnston, op. cit., p. 2011.
3 This holds only so long as calcite is the stable phase. If the salt-concentration
is such that some other carbonate (e.g., a double carbonate) is the stable phase, the
appropriate constant must be employed in place of that characteristic of calcite.
734 JOHN JOHNSTON AND E. D. WILLIAMSON
untrustworthy.t On the other hand, the concentration of free CO,
in any water, at a given temperature, can be calculated by means
of the known absorption coefficient of CO,, if the proportion of CO,
in the atmosphere with which it has been in contact is known;? and
as at the present time this proportion is usually close to 3 parts in
10,000 the corresponding solubility of calcite in natural waters
should be close to the values given in Table II. Consideration of
the published analyses from this standpoint leads to the conclusion
that the surface layers of the warmer portions of the sea (in so far
as they have been investigated), as well as many river waters,‘ are
substantially saturated with calcite. Murray,’ in adverting to this
question, states the opinion that ‘the ocean as a whole remains just
about saturated for calcium carbonate’’; but this statement is
without doubt too sweeping, except in the sense that the concentra-
tion of CaCO, throughout the ocean is probably as great as it is in the
warm surface layers. But there isalsomoredirectevidence. Thoulet®
t The titration methods which have usually been employed for the determina-
tion of free CO.—and to some extent of combined CO.—are altogether untrustworthy,
since the results depend upon the amount of indicator added and upon other factors
which have not been adequately controlled. This question is discussed at length in
another paper (J. Johnston, Jour. Am. Chem. Soc., XX XVIII [1916], 947). Cf. also
Morgulis and Fuller, Jour. Biol. Chem. XXIV (1916), 31.
2 With regard to the solubility of COz in a sea-water see C. J. J. Fox, Trans.
Faraday Soc., V (1909), 68.
3See F. W. Clarke, Data of Geochemistry; but especially a paper by E. Dubois,
“The Amount of the Circulation of CaCO; and the Age of the Earth.” (Proc.
Acad. Wetenschappen Amsterdam [1901], pp. 43-62). Cohen and Raken (ébid.
[t901], p. 63) have determined directly the solubility of CaCO; in an artifical sea-
water at 15° and found about 55 parts per million; but their method of experiment
is not unexceptionable and would tend to yield low results; they also conclude that
this sea-water is saturated with CaCO;. Wells also (Jour. Wash. Acad. Sci., V
[x915], 621) points out that the amount of carbonate carried by the Mississippi
River diminishes steadily as it flows southward, i.e., in the direction of rising
temperature.
4Indeed, the amount carried by many rivers is much in excess of the true solu-
bility, indicating that some of it is in suspension. Where such a river reaches the sea,
the salts cause the flocculation of this and any other suspended material, and in this
way induce the formation of deposits there.
5 Murray and Hiort, The Depths of the Ocean (1912), p. 180.
6 J. Thoulet, “‘“Etude bathylithologique des cétes du Golfe de Lyons,” Annales
de I’ Institut Océanographique, IV, fasc. VII (1912), pp. 32-35:
AGENCIES IN DEPOSITION OF CALCIUM CARBONATE 735
studied silt grains taken from various parts of the Gulf of
Lyons, and observed upon them films of calcium carbonate which
had been precipitated during the process of sedimentation; this
shows, therefore, that the water of the Gulf of Lyons is substantially
saturated with CaCO;. Recent experiments of A. G. Mayer™ show
that the sea-water about the coast of Florida is likewise substantially
saturated, for shells exposed to it for a year lost no significant weight.
Moreover, the investigations of T. W. Vaughan? on coral reefs ‘‘ show
that submarine solution is not effective there [about Florida] as all
the bays, sounds, and lagoons are being filled with sediment,” a con-
clusion which accords “with the conclusions reached by numerous
investigators in the Pacific, which are that the more or less continu-
ous walls inclosing lagoons have been formed by constructional geo-
logic processes and that lagoon channels and atoll lagoons are not
due to submarine solution.” |
The evidence just presented leads us, therefore, to the opinion
that the surface layers of the ocean, except in the polar regions and
within currents of cold water—in other words, the warmer portions
of the ocean water—are substantially saturated with CaCO;. We
wish to point out specifically, however, that this belief cannot be
regarded as established (or indeed disproved) until trustworthy deter-
minations of the several quantities concerned have been made;
indeed, to emphasize the necessity of such investigations is the prime
purpose of this paper. But in this connection it may be remarked
that a permanent deposit of limestone can hardly result unless (1) the
final solution locally in contact with it is saturated, or (2) the pre-
cipitated carbonate is protected from the water by an organic tissue
or otherwise, or (3) the process of deposition is rapid, in water circu-
lating very slowly or not at all, under which conditions re-solution
by diffusion is very slow.
In this paper, which is dealing primarily with the chemical argu-
ments, it would be out of place to take up the geologic lines of evi-
dence which indicate that the ocean as a whole is not saturated with
CaCO,, for this point is not at issue; but we may fitly advert to the
tA. G. Mayer, Proc. Nat. Acad., II (1916), 28.
2T. W. Vaughan, Am. Jour. Sci., XLI (1916), 133. See also his earlier papers,
especially in the Year Books of the Carnegie Institution of Washington.
736 JOHN JOHNSTON AND E. D. WILLIAMSON
chemical arguments which have been adduced in favor of this posi-
tion. Thus Tolman writes:
As direct evidence that the ocean is not saturated with calcium acid car-
bonate, we find (1) of the many hundred bottles of the Challenger’s samples
of sea-water, from all depths and collected at all temperatures, kept several
years, only one or two showed deposit of lime.?_ (2) Sea-shells from the bottom
of the Pacific show corrosion and re-solution.3 The Pteropod shells are not found
below fifteen hundred fathoms, and two thousand eight hundred fathoms is the
limit for the globigerina ooze.4 (3) Thoulet found by actual experiment that
sea-water will dissolve calcium carbonate from shells, corals, etc. (4) Usiglio,
studying the evaporation of the Mediterranean water at Cette, found that no
precipitate was formed until the specific gravity of the sea-water increased
from 1.02, the specific gravity of the unevaporated water, to 1.0503, when the
first precipitation begins, composed largely of calcium carbonate with ferric
oxide.®
Let us now consider these arguments severally. (1) That samples
of surface water did not deposit CaCO, on standing is not good evi-
dence one way or the other unless conditions were carefully con-
trolled, for change of temperature or of concentration of CO, would
influence the result. (2) This shows, of course, that the lower (and
colder) layers are not saturated; to this point we revert later.
(3) Reference to Thoulet’s paper shows that his work proves nothing
as to the point in question, for neither the temperature nor the
partial pressure of CO, was controlled. Indeed, he writes: “In the
case of marble . . . . and of coral, the loss [of weight] in sea-water
was negative. This result arises from the fact that small algae
appeared . . . . the weight of which confuses the result.” (4) This
observation also is no proof, in view of the well-known fact that
solutions of calcium carbonate exhibit a great tendency to super-
saturation when no solid CaCO; is already present; therefore it
shows only that, when the density was 1.05, the degree of super-
saturation had become so great that precipitation took place. From
tC, F. Tolman, Jour. Geol., VII (1899), 604.
2 Challenger Reports, p. 221.
3 Jour. Geol., I, 504.
4 Challenger Reports, p. 221.
5 Comptes rend., CVIII, 753.
6 Encycl. Brit., XXI, 220.
AGENCIES IN DEPOSITION OF CALCIUM CARBONATE 737
this discussion, then, it follows that three of these arguments are not
conclusive as to the point at issue.
Let us now consider the modes in which CaCO, may be precipi-
tated. We shall for convenience arrange them under three heads,
which, however, cannot be sharply differentiated: (1) direct evapo-
ration of the water; (2) through organic agencies; (3) change of
conditions, especially of temperature and concentration of free CO,,
these being the predominant inorganic factors.
1. By direct evaporation.—When natural waters evaporate, CaCO,
is commonly (though not necessarily) the first substance to be
deposited, and may be very largely precipitated before any of the
other salts separate;' the more soluble salts, moreover, will tend to
be leached out of such deposits. But since all such deposits are of
obvious origin and of minor importance, they need not detain us
further.
2. Deposition through organic agencies —The agencies which come
under this category are of the greatest importance and are predomi-
nantly responsible for the deep-sea deposits, yet little as to their
mode of action can be definitely stated until more is known about
the biologic processes involved. This question is altogether beyond
the scope of this paper; we shall mention merely two established
effects of organic agencies, reverting to them later: viz., the abstrac-
tion of free CO, from fresh water by growing plants,? and the
production of ammonia in sea-water by decaying organisms or by
bacteria. Both of these effects disturb the equilibrium in a solu-
tion originally saturated with CaCO,, the former by diminishing the
concentration of H,CO,, the latter by increasing the concentration
tCf. Van’t Hofi’s Ozeanische Salzablagerungen.
2 Various references to these effects are given in Clarke’s Data of Geochemistry
under ‘“‘Limestone.”’ See especially C. A. Davis, Jour. Geol., VIII (1900), 485, 494;
IX (1901), 401. According to Murray, the calcareous algae common in the warmer
oceans no doubt secrete their skeletons in the same way. See also S. T. Powell,
‘Effect of Algae on Bicarbonates in Shallow Reservoirs,” Jour. Am. Waterworks
Assoc., II (1915), 703.
3 This question has been discussed recently by G. H. Drew (Carnegi (Institution
Publ. No. 182 [1914], p. 7), and by Kellerman and Smith (Jour. Wash. Acad. Sci., IV
[1914], 400), and so need not be treated here. Many decaying organisms and bac-
teria (as well as the respiration of animals) produce COz, and to this extent they would
act as an adverse influence on the deposition of CaCO.
738 JOHN JOHNSTON AND E. D. WILLIAMSON
of CO; directly,’ the net result in either case being the precipita-
tion of an amount of CaCO, which could readily be calculated by
means of the equilibrium equations if the amount of CO, abstracted,
or of ammonia produced, were known. But by this we do not imply
thatan organism cannot secrete calcium carbonate except from a solu-
tion already saturated with it. Nevertheless the possibility is open
that the effects just considered may sometimes be in reality examples
of the changes in conditions to be next considered—that the organism
may be merely the agency which localizes the process, the mechanism
which occasions the precipitation. It may even be that certain
bacteria are abundant where CaCO, is being precipitated because
there they can easily secure material—particularly CO.,—needed for
their life-processes; on this. basis they would be concomitants,
rather than causes, of the deposition of the carbonate.
3. Change of conditions.—The important physico-chemical factors
are temperature, and concentration of free CO,, of the water; in com-
parison with these two all other such factors are entirely subsidiary.
As an illustration of the magnitude of the effect producible by change
of these factors, a change in the proportion of CO, in the air in actual
contact with the solution from 3.3 down to 3.0 parts per 10,000—a
change? which may occur at the present time—of itself decreases the
solubility from 65 to 63 parts per million, and so will cause the ulti-
mate precipitation of the corresponding quantity of CaCO, from a
solution already saturated with it. A similar amount will be
deposited? if the temperature of the saturated solution rises about
2° C., the proportion of CO, in the air remaining constant; under
these circumstances the concentration of free CO, in the water falls,
and its diminution is responsible for the larger part of the diminished
t The production of free ammonia causes an increase in the concentration of OH
and therefore an increase in [CO 5], since the quotient [OH }/[CO ] is constant when
P is constant, in accordance with the equation already given. It may be noted that
the production by the decaying organisms of an ammonium salt such as NH,NO; or
(NH,)2SO, would tend to increase the solubility of CaCO; and hence would not favor
its deposition.
2 The range of variation in the course of geologic time has in all probability been
very much greater than this with correspondingly larger possible consequences.
3 This of course implies that supersaturation does not take place; but in the sea
supersaturation is highly improbable by reason of the great abundance of appropriate
nuclei always present.
AGENCIES IN DEPOSITION OF CALCIUM CARBONATE 739
solubility, since the diminution of the solubility-product constant
of calcite with temperature is, as we have seen, proportionally less
than that of the absorption coefficient of CO,.
The abstraction of CO, from a saturated solution results ulti-
mately, then, in the deposition of CaCO,, no matter what the agency
which abstracts the CO,. This agency may be a diminished pro-.
portion of CO, in the air, or a higher temperature, or both; or it may
be organisms which make use of the CO, in their vital processes, or
the production by bacterial action of ammonia, which indirectly
achieves the same result; or, in short, it may be any way in which
the concentration of CO, may possibly be diminished. Conse-
quently, if the surface layers of the sea are saturated, as we believe
they are, precipitation of CaCO, will be brought about wherever
any of the foregoing agencies are operative.
In this connection two points which are the consequence of
accepting erroneous chemical data are to benoted. Thus Davis‘ in
his excellent work on marls has made a slight slip. He observed that
on bubbling oxygen gas through a‘solution containing CaCO, the
latter was precipitated, and he attributed this effect to a specific
action of the oxygen; but any other gas would have produced the
same effect, which was actually due to the sweeping out of the CO,
from the solution. Nor is it necessary to consider, when ammonia is
being produced, whether it appears as hydroxide or as carbonate, or
whether there is a subsequent metathesis with calcium sulphate or
chloride or some other reaction; in either case the net result can be
predicted immediately from a consideration of the effect of the added
substance upon the concentration of calcium-ion and of carbonate-
ion,? and of the magnitude of the product [Cat*] [CO%] in relation
to its precipitation value. To some this procedure may appear
complicated; in reality, while it pays no heed to those easily derived
arithmetical equations so often considered as representing reactions,
it takes into account the several equilibria which must be adjusted,
tC. A. Davis, Jour. Geol., VIII (1900), 487.
2 Change of concentration of CO% affects, and is affected by, the concentration of
HCO, and OH, these being all dependent variables; see Johnston, of. cit.
3 Provided that calcite is still the stable solid phase in equilibrium with the solu-
tion; cf. footnote 3, p. 733.
740 JOHN JOHNSTON AND E. D. WILLIAMSON
and is the only procedure which will yield accurate results and lead
to correct conclusions. Moreover, a comprehension of this question
is desirable because this apparently complex equilibrium is typical
of what takes place in many other systems, aqueo-igneous and igne-
ous as well as aqueous; it is in but very few cases, however, that we
know even what molecular species are important factors in the
equilibrium, and in still fewer is any information available as to the
quantitative relations at equilibrium.
There has, moreover, been considerable misapprehension as to
the réle of hydrostatic pressure in increasing the solubility of CaCO,;
thus in a recent paper Daly' writes: ‘On account of the higher
temperatures and lower bottom pressures (pressure increasing the
solubility of the carbonate) of the shallower water we should expect
the rate of chemical precipitation of calcium carbonate at the bottom
to be concentrated in the neritic (epicontinental) and shallower
bathyal regions.” And many smiliar statements relative to the
effect of hydrostatic pressure might be quoted. As a matter of fact,
the hydrostatic pressure? acting on the water is of itself an abso-
lutely negligible factor; thus water a mile below the surface of the
sea will hold in solution an amount of CaCO, which does not differ
“by an appreciable quantity from the amount the same water at the
surface will hold, provided that the concentration of free CO, and
the temperature be the same in both cases. The increased solubility
with depth in the ocean is due entirely to the lower temperature of
the water and to the increased proportion of free CO,, but not at
all to the increased hydrostatic pressure there prevailing.
The only pressure which does affect the solubility is the partial
pressure, i.e., the proportion, of CO, in the layer of atmosphere? in
™R. A. Daly, Bull. Geol. Soc. Am., XX (1909), 156; also in “Geology of North
American Cordillera,” Memoir No. 38, Geol. Survey of Canada, Part II (1912), p. 651.
Italics are ours.
2 Increase of hydrostatic pressure decreases the solubility of some substances. In
any case the effect is very small indeed; its magnitude and direction can be calculated
if the appropriate data on volume changes are known. Cf. Johnston and Niggli, Jour.
Geol., XXI (1913), 504, where references are given.
3 The proportion of CO, in the air increases, ceteris paribus, as we pass from higher
to lower levels; but this is a factor of no moment to the present discussion because
the diffusion downward through the water is in all probability very slow in comparison
with the natural circulation of the water.
AGENCIES IN DEPOSITION OF CALCIUM CARBONATE 741
contact with the solution, for there is a definite and quickly attained
equilibrium between the proportion of CO, in the adjacent atmos-
phere and the concentration of free CO, in the water, the factor of
proportionality being the absorption coefficient (the solubility) of
CO, in the solution at the particular temperature. It is true that
water at depth can hold more CO, in solution, if it gets hold of it,
for in that case bubbles of CO, gas cannot form until its virtual
pressure just exceeds the hydrostatic pressure; but slow diffusion
upward would tend to equalize the concentration at various depths.
In the ocean, on the other hand, the content of CO, is only what it
was able to absorb when at the surface, supplemented by that which
has been produced by organic processes—the latter being in all
probability but a small fraction of the whole in deep water.t How-
ever this may be, it is manifest why the water at depth should con-
tain more CO,, for its present low temperature, retained from its
polar days, establishes the fact that when at the surface in contact
with the atmosphere it was cold, and lowering of temperature
increases very markedly the amount of CO, which water can absorb
through contact with an atmosphere containing a constant propor-
tion of CO,.?. This fact, combined with its present low temperature
—for, as we have seen, lowering of temperature of itself increases the
solubility of CaCO,—suffices to account for the well-known fact that
all shells and tests disappear in the depths of the ocean.
Now let us revert to the consequence of abstraction of CO,, and
consider what will happen when, in the course of the oceanic circu-
lation, this cold water, which carries more CO, and more CaCO, than
the warmer surface waters,‘ reaches the surface and is slowly warmed.
t Buchanan (Proc. Roy. Soc., XXII [1874], 483) writes: “‘Down to nearly 2,000
fathoms life is still abundant; below this depth, however, the amount rapidly decreases
till, at about 2,800 fathoms, it is, for carbonic acid producing purposes, practically
extinct.”
2 Thus in contact with any atmosphere, water (or a dilute salt solution) absorbs
about twice as much CO: at o° as at 20°.
3 See the report of the Challenger expedition or the work of Sir John Murray.
In the present connection it is immaterial whether these shells consist of calcite or
aragonite, although assertions to the contrary may be found.
4This appears a necessary prerequisite, no matter what be the mechanism of
precipitation. Dittmar, in his article in the Encyclopaedia Britannica, states that there
is a slight but indubitable increase in concentration of calcium with depth. Moreover,
742 JOHN JOHNSTON AND E. D. WILLIAMSON
In the first place, it will gradually lose CO, to the air, the residual
concentration of free CO, being dependent at any moment upon the
temperature of the water and the proportion’ of CO, in the air at
that place. The consequence of this loss is that the amount of cal-
cium in solution will at some point exceed the concentration which
the water is able to hold in solution—r, in other words, the product
[Cat*] [CO] reaches its characteristic precipitation value—where-
upon precipitation? sets in, and continues thereafter so long as the
temperature continues to rise. This process is without doubt taking
place now in tropical and subtropical regions wherever and whenever
the necessary conditions are fulfilled. It has been correlated’ with
the abundant bacterial and planktonic life found under such cir-
cumstances, and there would seem to be little question that the organ-
isms are a factor in the process, if only in the sense of catalyzing it.
But may it not be, in some cases at least, that the organisms are
abundant there because of the abundance of the CO, available for
their life-processes in such water? For it is to be borne in mind that
the precipitation of CaCO, is accompanied by the setting free of an
equivalent quantity of CO, which, if not used up in the sea, will pass
into the atmosphere. Be this as it may, the physico-chemical factors
are in themselves competent to account for the precipitation’ of
CaCO, on a large scale, and the prerequisite conditions for deposition
by this means do not differ materially from the postulates required
for precipitation by bacterial action or by organisms generally.
Buchanan (Proc. Roy. Soc. London, XXIV [1876]) writes: “There is usually more
COz in waters taken from the bottom and intermediate depths than in surface water;
but if regard be had to the temperature of the water, it will be seen that there is but
little difference in the amount in waters of the same temperature from whatever depth
they have been derived.’ It is to be observed that these determinations all refer to
low latitudes; conditions in the Polar regions may well be different.
t All experiments indicate that this proportion departs in general very little from
3 parts in 10,000, except in or near large towns. Off the west coast of Greenland,
however, amounts up to 7 parts in 10,000 were observed by Krogh (Meddelelser om
Gronland, XXVI [1904], 409).
2 Supersaturation is under these conditions obviously a negligible factor.
3G. H. Drew, Carnegie Inst. Publ. No. 182 (1914), p. 7; Kellerman and Smith,
Jour. Wash. Acad. Sci., IV (1914), 400. See also recent papers by T. Wayland
Vaughan.
4 Likewise for its re-solution.
AGENCIES IN DEPOSITION OF CALCIUM CARBONATE 743
Indeed, there are several facts which point to a parallelism between
the amount of lime secreted by organisms and the degree of satura-
tion of the sea with respect to CaCO,; thus the animals of the warm
seas secrete more lime, on the average, than the same types in cold
seas;t and, according to Murray,” ‘“‘on the whole, lime at the present
time appears to be accumulating toward the equator.”’ These obser-
vations directly corroborate the idea that solubility is a significant
factor even in the secretion of lime by organisms; that the decreasing
abundance of calcareous organisms toward the polar regions is a
question not only of the decrease of general vitality (rate of growth
and of reproduction) with lowering of temperature, but also of the
decreasing capacity’ of the organism to secrete CaCO, from colder
sea-water, this being associated with the fact that, though the con-
centration of lime is no smaller in the colder water, the degree of
unsaturation is greater the colder the sea-water.
According to Murray, ‘‘a limited amount of purely inorganic pre-
cipitation does, indeed, take place in coral reefs and some shallow
water deposits and in the Black Sea.”4 Now it has been argueds
that chemically precipitated limestones are due to the production
of ammonia by decaying organic matter; according to this view such
limestones could form only when conditions were such that a long-
continued process of persistent decay was possible. According to
the view emphasized in the present paper—and, be it noted, this is
primarily a chemical, rather than a geological, question—chemical
tSee citations from the Challenger Reports, in Chamberlin, Jour. Geol., VII
(1899), 576-77.
2 The Depths of the Ocean, p. 180. “In very deep water, even within the tropics,
the calcareous shells do not accumulate on the bottom, being apparently removed
through the solvent action of sea-water, and with increasing depth the Globigerina
ooze passes gradually into another pelagic type, usually Red Clay” (p. 164).
“Pteropod ooze is limited to the tropical and subtropical regions, usually in the
neighborhood of oceanic islands and on the summits and sides of submarine elevations;
it is found in relatively shallow water, and covers a relatively small extent of the
ocean floor” (p. 167).
3Tt would be of interest to know if these calcareous organisms could secrete
CaCO; from colder water kept saturated with calcium carbonate.
4 The Depths of the Ocean, p. 178.
5 Most recently by R. A. Daly, Bull. Geol. Soc. Am., XX (1909), 153; in more
extended form in Memoir No. 38, Geol. Survey Canada (1912), pp. 643 f.
744 JOHN JOHNSTON AND E. D. WILLIAMSON
precipitation would take place wherever, and so long as, a current
of water saturated with calcite was being warmed. ‘These views are
not at all mutually exclusive; but their implications differ, and
it ought to be possible to decide by appropriate observation and
deduction in how far either has been a dominant cause on a large
scale.
The magnitude of the scale of this presumed process of precipi-
tation through purely inorganic agencies depends primarily upon the
rate of circulation and upon the amount of calcium carried by this
water rising to the surface. We shall now consider the competence
of these agencies as geologic factors. In doing so let us suppose that
a cold current of sea-water is not saturated with CaCO, until it has
reached a temperature of 15°, and that this current after traveling
1,000 kilometers (600 miles) has attained a temperature of 20°;
further, that the water in this stretch of 1,000 km. is changed 10
times a year, corresponding to a current speed of 1,000X 10/365 or
27.4 km.aday. Now this water in being warmed from 15° to 20°
would precipitate 5.4 parts CaCO; per million by weight, or 2 parts
per million by volume; on these assumptions,’ therefore, in the
course of a year the mean thickness of the deposit (presuming that
all of the precipitate finally settles to the bottom within this stretch)
would be 2/1,000,000 of the depth of the current. Hence if the
depth of the current is 100 m., the average deposit over the whole
area would be, on the specific assumptions just mentioned, 2 mm.
yearly.2 This estimate is probably a minimum, particularly because
we have supposed that deposition would take place over the whole
area, whereas in reality deposition would be localized (e.g., if there
is, as is likely, a more rapid warming up at some places) so that the
deposits actually formed would be thicker. Moreover, the deposit
would be redissolved whenever the current is underlain by colder
unsaturated water; therefore actual deposits belonging to this cate-
gory should occur only in localities bathed by currents which are
«The numerical values adopted were chosen as being reasonable; in any case
these calculations will serve as an illustration, and anyone may make similar calcu-
lations using whatever numerical values he deems most consonant with the facts.
2 This corresponds to about 5,000 tons CaCO; per square kilometer per year,
or to a thickness of about 8 inches in a century.
AGENCIES IN DEPOSITION OF CALCIUM CARBONATE 745
warm and hence comparatively shallow and rising in temperature
as they proceed. Consequently, if deposits of CaCO, are being
formed in this way—and there is no direct evidence at hand which
contradicts this view—it should be possible to correlate the position
and rate of formation of such precipitated deposits with other things
by means of series of bathymetrical observations on the manner of
flow of the currents, the temperature of the water, and, above all,
the concentration of free CO,. As regards the latter, it may be said
that the methods hitherto in vogue are very faulty indeed,‘ and that
systematic, accurate determinations of the free CO, (which can be
made by proper choice of method) are very much to be desired, not
only on account of their bearing on the present question, but because
an accurate knowledge of the concentration of free CO, is of high
importance? in connection with many biological problems, both
theoretical and practical.
Nor would the establishment of this presumed correlation
between deposits of CaCO, and the physico-chemical conditions pre-
vailing in the ocean be of importance only in relation to present-day
formations belonging to this category; it would also be of use in
interpreting past deposits of this character which have persisted and
in co-ordinating them with other factors. For the rate of formation .
of such deposits (including the limiting case of zero rate) depends
obviously upon the mode and rate of circulation of the ocean and
the amount of calcium carried by the water rising to the surface,
secondarily, therefore, upon the amount of calcium carbonate
brought down by the rivers to the sea; all of which depend ultimately
upon the physiographic and petrologic character of the land surface,
upon the magnitude of the seasonal variations and regional differ-
ences, upon the climate over the whole earth, and upon the propor-
tion of CO, in the atmosphere. It would lead too far to discuss this
question in all its bearings; in order to show the importance of the
t See Johnston, Jour. Am. Chem. Soc., XX XVIII (1916), 947.
| 2 The free and combined CO:z and the alkalinity of the solution are not independent
variables, a fact often forgotten; and doubtless many effects ascribed to a change in
alkalinity are due equally, or primarily, to a change in the CO? equilibrium in the
solution.
3 The discussions of Chamberlin (Jour. Geol., VII [1899], 545, 667, 757), Tolman
(ibid., p. 585), Krogh (Meddelelser om Gronland, XXVII [1904], 334), and others,
require some revision in the light of data available since that time.
746 JOHN JOHNSTON AND E. D. WILLIAMSON
last factor—apart altogether from the influence of CO, as an agency
disintegrating the rocks—we have calculated the concentration of the
free and combined CO, in sea-water at three temperatures for several
proportions of CO, in the atmosphere. The specific assumptions
made in these calculations are: (a) that the molar absorption coeffi-
cient (c) of CO, is the same as ina 0.6 N (3.5 per cent) solution of
sodium chloride; (b) that the water is always saturated with respect
to calcite, so that we are justified in using the solubility-product
constant (K() corresponding to the temperature; (c) that the degree
of ionization of the carbonate is 0.6, a value which is probably high
rather than low.’ On this basis the formula becomes
A=total CO,=cP+V 11200cK/P/o.6,
where the first term represents the free CO, and the second the total
combined CO,, each expressed in moles per liter; whence by multi-
plication by the factor 0.044 one obtains the result in grams CO,
per cubic meter (parts per million) as given in Table III.
TABLE III
THE CONCENTRATION OF FREE (f), COMBINED (0), AND ToTaL (A) COz—ExPRESSED
IN GRAMS COz PER CUBIC METER (PARTS PER MILLION)—IN SEA-WATER AT
SEVERAL TEMPERATURES AND SEVERAL PARTIAL PRESSURES (P) OF COz IN THE
ATMOSPHERE; CALCULATED ON THE BASIS OF THE SPECIFIC ASSUMPTIONS MEN-
TIONED ABOVE
10° 20° 30°
CO: in ADJACENT c=0.0463 €=0.0335 c=0.0260
ATMOSPHERE AS Kco=1.06X10—8 Ko=0.93X1078 Kco=0.81X107—8
Partial
Parts per
eon Become f 6 A if b A tf b A
©.00025 | 0.51 | 81.5 82 | 0
.0003 0.61 | 86.6 87 | 0
-00025 | 0-71 || OL: xr 92 | 0
.003 6512 |1870 |) 1935 4.
0.03 61.2 |402. 463 |44
The figures for total CO,, derived in this way, are in substantial
agreement with the results of analyses of sea-water; in any case the
t Murray and Hiort (The Depths of the Ocean [1912], p. 175) estimate the aggregate
degree of ionization in sea-water to be 0.9; but this is undoubtedly much too high.
AGENCIES IN DEPOSITION OF CALCIUM CARBONATE 1747
relative values for the different conditions are probably good even
if the absolute values are inaccurate. According to the table, the
concentration of total CO, in water at constant temperature varies
practically as the cube root of P, for the small values of P; in other
words, a change of 3 per cent in the present proportion of CO, (e.g.,
from 3.1 to 3.0 parts per 10,000) will produce a change of but 1 per
cent in the concentration of total CO, in the sea-water. Likewise
under present conditions (i.e., P=0.0003) the total CO, in the ocean
decreases about 1.5 per cent of its value for each degree of rise in
temperature. At the higher pressures of CO, the proportion of free
CO, in the water becomes relatively much more important; but a
hundred-fold increase in the proportion in the adjacent air would
cause only a fivefold increase in the total CO, in the sea. In this
estimate and in the subsequent discussion, be it noted, the assump-
tion is implicit that the water is continuously saturated with CaCO,
at 15° for all values of P, which in turn implies that conditions were
such that the rivers transported to the sea sufficient lime to achieve
this. On this basis, therefore, if the present amount of CO, in the
atmosphere were increased a hundred fold, the total amount of CO,
in atmosphere and ocean would be only six times as much as it is
now; the conditions of equilibrium always being such that a chance
in the proportion of CO, in the atmosphere is minimized, not through
a permanent change in the proportion of free CO, in the sea (and
of its alkalinity), but ultimately by means of the precipitation or
solution of a definite quantity of CaCO3.
Let us now make a computation of the ratio of the total amount
of CO, in the whole ocean to that in the whole atmosphere, this being,
of course, a measure of the capacity of the ocean to regulate the pro-
portion now present in the atmosphere. We assume again that the
ocean as a whole would be saturated with CaCO, if its temperature
were 15°,! and that its mean depth is 3,600 meters;? on this basis the
mean amount of CO, under each square meter of surface of the sea
is 813,600 gm. or 290 kg. The mean amount above each square
« This is just equivalent to the assumption that the average proportion of CaCO;
throughout the ocean is that which corresponds to its solubility at 15°, about 60-70
parts CaCO; per million for values of P not far removed from 0.0003. Ci. Table I.
2 See Encycl. Brit., article “Ocean.”
748 JOHN.JOHNSTON AND E. D. WILLIAMSON
meter of the earth’s surface (sea and land together) is 3 kg.; for if
the proportion of CO, in the air at the earth’s surface is 3 parts per
10,000, the proportion in the whole atmosphere is 2 in 10,000 by
volume, hence 3 in 10,000 by weight, or 3 kg. per square meter.
Consequently, since the ocean covers about 71 per cent of the total
surface of the globe, the ratio
total CO, in ocean __ 290X0.71_¢
total CO, in air 3 ae
In other words, the ocean contains about 70 times™ as much CO, as
the air, on the basis of the assumptions specified above. On this
basis the total CO, now present in the ocean and atmosphere com-
bined would form a layer of CaCO, only about 17 cm. thick over the
whole globe, or about 86 cm. (nearly 3 feet) over one-half the present
land area; likewise if the amount of CO, in the atmosphere were 100
times as much as at present, the corresponding values would be
slightly more than 6 times as large, namely, 110 cm. over the globe,
or 550 cm. (18 feet) over one-half the present land area. The
possible deductions, however, must remain uncertain until series
of simultaneous accurate determinations of free and total CO.,
temperature, and salinity in the sea at various depths and in different
localities shall have been made.
The precipitation of CaCO, in forms other than calcite——Besides
calcite, which is the stable crystalline form of CaCO, under all
ordinary conditions, there are two unstable crystalline forms, aragon-
ite and yu-CaCO,;, which may precipitate under certain circum-
stances. This whole question is discussed at length in another
paper, to which the reader desirous of further information is referred ;?
we shall here merely recapitulate the conclusions relevant to the
present discussion. The existence of the yu-form in nature has not
been definitely established, possibly by reason of the fact that some
of the criteria which have been used to differentiate the several forms
of CaCO, have not been unexceptionable, possibly on account of its
t This estimate is higher than that (27 times) of Krogh (Meddelelser om Gronland,
XXVI [1904], 420) or that (55 times) given in Chamberlin and Salisbury’s Geology,
II, 661, which see, with respect to the whole discussion.
2 “The Several Forms of Calcium Carbonate,” Johnston, Merwin, and Williamson,
Am. Jour. Sci. (4), XLI (1916), 473.
AGENCIES IN DEPOSITION OF CALCIUM CARBONATE 749
instability, for in presence of water the u-form transforms to calcite
in a few days. Calcite also appears as spherulites and as “‘amor-
phous” CaCO,; but there is little question that the divergent prop-
erties of the latter are due entirely to its fineness of grain, i.e., to its
extent of surface in proportion to its mass. Consequently the only
form other than calcite which we need consider here is aragonite.
Apparently aragonite is formed in nature (a) through organic
agencies (e.g., in certain shells), (6) by deposition from hot springs,
(c) when an isomorphous carbonate is present to serve as nucleus,
and (d) by chemical precipitation in saline waters, even at ordinary
temperatures, under circumstances which we are unable to specify
except by saying that the presence of sulphate appears to be a
favorable factor. But pure aragonite cannot persist for any length
of time in presence of water and calcite, hence only in special cir-
cumstances will it be found persisting in the sea. There is, however,
the possibility that aragonite may take up in solid solution enough
material to bring its own solubility below that of calcite, and hence
in the saline solution in equilibrium with the solid solution to render
the latter stable with respect to calcite; on this basis it is possible
that such impure aragonite may persist in contact with sea-water
under certain circumstances, although when exposed to the action
of meteoric waters it would soon transform to calcite. However this
may be, the circumstance that CaCO, precipitates otherwise than as
calcite would not of itself affect appreciably anything stated in this
paper, since the whole effect would be that ensuing upon the substi-
tution for the solubility-product constant of calcite of the corre-
sponding value for the other form, the latter being certainly no more
than twice as great as the former; so the precipitation of the less
stable forms is therefore of only subsidiary importance in the present
connection.
Summary.—Though organic agencies are predominantly respon-
sible for the deposition of calcium carbonate, yet the purely inorganic
factors should also be taken into account in discussions of the mode
of deposition: In this paper emphasis has been laid on one point
which has not received adequate recognition; namely, the concen-
tration of calcium relative to the limiting saturation concentration
of calcium carbonate under the particular conditions, or, in other
750 JOHN JOHNSTON AND E. D. WILLIAMSON
words, the relative degree of saturation with respect to calcium car-
bonate in the ocean. The importance of this factor is obvious if we
recollect that the chance of a permanent deposit is, ceteris paribus,
greater the more nearly saturated the surrounding water is; its
neglect is doubtless due to the erroneous and misleading statements
as to the solubility of CaCO, which have been prevalent. The solu-
bility under specified conditions can now be calculated with the
requisite accuracy; it is affected materially by variations of tem-
perature and of concentration of free CO, such as occur in nature.
For example, a change in the proportion of CO, in the adjacent air
from 3.2 to 3.0 parts per 10,000, or an increase of temperature of
2° C. would result ultimately in the precipitation of about 2 gm.
CaCO, from every cubic meter of a solution saturated with it.
Comparison of the solubility as calculated with the available ana-
lytical data indicates that the warmer surface layers of the sea are
substantially saturated with respect to calcite, and consequently that
precipitation is to be expected wherever the water is being warmed
or is losing CO,, or both, and this independently of any other
agencies. Indeed, these inorganic factors must be considered no
matter what may be the agency inducing precipitation; for example,
there is ground for believing that calcareous organisms are more
abundant the more nearly saturated with CaCO, the water is. The
view here advocated, that a somewhat greater réle be assigned to the
inorganic factors than has hitherto been usual, does not conflict with
other views—it merely shifts the emphasis a little; nor does it con-
flict with any facts that have been definitely ascertained. Its precise
importance can be determined only by accurate determination of
temperature, salinity, and particularly of concentration of CO,—
free and total—of the water carried out systematically over the
ocean; the results of such an investigation, properly carried out,
would have an important bearing on many outstanding biological,
as well as geological, problems.
NOTES ON THE STRUCTURAL RELATIONS OF
AUSTRALASIA, NEW GUINEA, AND
NEW ZEALAND
E. C. ANDREWS
Sydney, New South Wales, Australia
Introduction
Previous Work Done and Scope of Present Work
Growth of Australasia from Pre-Cambrian to Recent Time
Evidence of the Ore Deposition
Conclusion
INTRODUCTION
The accompanying brief note is an attempt at the co-ordina-
tion of our increasing knowledge of the structural development of
Australia and the neighboring islands.
The ideas given in this note are intended only as a temporary
viewpoint from which to consider the work of the great pioneers
of geology in Australia and as an inference or tentative hypothesis
to stimulate interest in those magnificent field problems in Austral-
asia, New Guinea, New Caledonia, and New Zealand, which call
so urgently for solution. In this way it is hoped that the scheme
here proposed will serve as a rough clue to the unraveling of certain
vexed questions in the stratigraphic and structural history of
Australia.
Several difficult points need explanation before any simple
account of the building of Australia would be possible. Thus in
the discussion of the Devonian it must not be forgotten that folds
supposed to be of this age occur in Northwest Australia. Highly
altered rocks of unknown age and of large area occur also in North-
ern and Northeastern Queensland, and the occurrence of these has
not been explained in the present note. Then again, it must not
be forgotten that our knowledge of some of the Permo-
Carboniferous rocks, such as the Gympie of the Queensland geolo-
gists, is far from satisfactory.
752
752 E. C. ANDREWS
Again, it is not known how many of the observations of the
older workers in connection with the strike of folds were merely
local and how many were conducted on a large scale.
Acknowledgments.—The writer is deeply indebted to Pro-
fessor Leo A. Cotton and Dr. W. N. Benson, of Sydney University,
for their kindness in reading the report in manuscript and for supply-
ing additional information as to literature on the pre-Cambrian
and Ordovician, and for kindly criticism of the notes on the Devo-
nian, the Permo-Carboniferous and the Trias-Jura.
Previous workers.—lIt is the desire of the writer at this stage of
our scientific development in Australia to draw attention to the
work of the pioneers of geology in the great island continent.
Australian pioneer geologists, in common with Australian explorers
and miners, and in common also with American pioneers, have
breathed the inspiration of their own mighty surroundings. Fore-
most among the pathfinders of geology in the country under
consideration—men who crossed trackless wastes and endured
untold discomforts in their pursuit of knowledge—were W. B.
Clarke, R. Daintree, and A. R. C. Selwyn; others who followed
in the track of these giants, but who nevertheless bore much of the
heat and burden of the day and were either worthy successors or
contemporaries of the pioneer trio, were H. Y. L. Brown, J. E.
Carne, T. W. E. David, W. Howchin, R. Logan Jack, A. Gibb
Maitland, R. Murray, S. Stutchbury, R. Tate, W. H. Twelvetrees,
and C. S. Wilkinson. Among them also must be named the
paleontologist, R. Etheridge, Jr., whose labors in the cause of
Australian paleontology have done so much to simplify the task
of the field workers. A whole group of younger enthusiasts have
built and are today building on the work laid down by these
pioneers.
PREVIOUS WORK DONE AND SCOPE OF PRESENT NOTE
The earliest definite statement known to the writer concerning
the building of Australia as a whole was made by T. W. E. David."
In this detailed account Professor David’s descriptions imply
« Presidential address on ‘The Growth of Australia,” Proc. Linn. Soc. N.S.
Wales, 1893, pp. 547-607.
AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND 753
the growth of Australia as from west to east. In 1911 the same
_ writer amplified his earlier statement and said: ‘Since the close of
Paleozoic time Australia has been subjected to broad warps, but not
to true folding except in the direction of New Guinea, where Cre-
taceous, and even early Tertiary, strata are highly folded. New
Guinea is thus a new fold region; and even in Australia tectonic
movements are newer as New Guinea is approached” (p. 59).
H. I. Jensen? also, in a later note, discussed the gradual growth
of the eastern portion of the continent.
Like David’s earlier reports, this paper of Jensen’s is important
and suggestive. Jensen approaches the problem of Eastern
Australian history also from the viewpoint of “‘petrological unity.”
He, however, considered that the folding of the Permo-
Carboniferous sediments was sporadic and had died out practically
in Northern New South Wales.
In 1914 David’ presented an epitome of Australasian geology.
In this he said: ‘‘The latest folding to which the earth’s crust in
Australia has been subjected belongs to late Carboniferous time”’
(p. 256). He qualified this, however, by the statement: “‘The
strata in the Permo-Carboniferous system are either perfectly
horizontal or disposed in broad open troughs and arches. Only in
the case of the strata of Drake and Undercliffe in New England
and the Ashford areas [New South Wales] and the Gympie area
in Queensland, are the strata of this system highly disturbed near
granite intrusions”’ (p. 267).
The reader is referred for a consideration of this statement to
the discussion of the field evidence in connection with the Permo-
Carboniferous. It will then be seen how incomplete is our knowl-
edge of the ageof the sediments of Eastern Australia lying to thenorth
of Sydney, and hence how great the need for caution to be exercised
in coming to any definite conclusion as to the scheme of structure.
=T, W. Edgeworth David, “Presidential Address,” Proc. Roy. Soc. N.S. Wales,
IQII, pp. 15-76.
2‘The Building of Eastern Australia,” Proc. Roy. Soc. Queensland, July, 1911,
Pp. 149-98.
3T. W. Edgeworth David, “The Geology of the Commonwealth” (Federal
Handbook), Brit. Assoc. Adv. Sci., Australian meeting, 1914, pp. 241-325.
754 E. C. ANDREWS
Origin and scope of present note-—The idea of writing a paper
similar to the present one was conceived as far back as 1905-6,
when the writer was surveying an area of folded sediments in
Northern New South Wales. Previous workers had considered these
beds as belonging to the older Paleozoic because they were strongly
folded, whereas the beds of known Permo-Carboniferous type in
Australia at that time were either horizontally bedded or only
moderately domed.
David, however, in connection with these beds, had pointed out
as far back as 1893: ‘‘I have, however, lately. come to the conclusion
that the whole of the Paleozoic sedimentary rocks of the Vegetable
Creek district, provisionally classed by me as Upper Silurian or
Devonian, are referable to the Gympie horizon’ [presumably
Carboniferous.—E. C. A.].
During the progress of the survey these beds were discovered to
contain many characteristic Lower Marine (Permo-Carboniferous)
fossils, as probably also some Upper Marine types. The area of
these Permo-Carboniferous types was proved to extend far to the
north and west afterward by the field work of Carne and the
writer.?
In Southern Queensland, near Warwick, these two observers
found Lower Marine rocks folded in the most complicated manner,3
while in 1908 during a visit to Mount Morgan, about 500 miles north
of the New South Wales border, they saw rocks indicated on the
Queensland geological map‘ as of the same age as the Warwick
types, also highly folded.
In 1901 Mr. C. Hedley and the writer traced rocks at intervals
from a little north of Townsville to near Cooktown, all highly con-
torted, and all shown on the Queensland geological map as of the
same age as the Warwick beds. ‘This caused the writer to consider
t “Presidential Address,”’ Proc. Linn. Soc. N.S. Wales, 1893, pp. 586-87.
2 J. E. Carne, “The Tin-Mining Industry of New South Wales,” Mineral Resources
No. 14, Dept. Mines, Sydney, N.S.W., 1911, pp. 54, 70, 71; E. C. Andrews, “‘The Drake
Copper and Gold Field, N.S. Wales,” Mineral Resources No. 12, Dept. Mines, Sydney,
N.S.W., 1908, pp. 3-11.
3 Drake Report. See plate opposite p. ro.
4R. L. Jack and R. Etheridge, Geology of Queensland, Brisbane (by Authority),
1892, plate 60.
AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND 755
the significance of the peculiar problem of the Permo-Carboniferous,
inasmuch as the whole of the work of the field officers of the geo-
logical survey of New South Wales had proved that the Permo-
Carboniferous strata south of the Hunter River (lat. 33° S.) lie
almost horizontally.
The independent testimony of the ore deposits of New Zealand
and Australasia was then examined, and the problem of Austral-
asian growth was formulated in the following terms:
During the progress of geological time folding movements in
Australasia retreated north and east, while ore deposition moved
parallel with these movements.
The growth of New Zealand does not appear to be known defi-
nitely, but the New Guinea and the New Caledonian movements
appear to have opposed the Australian direction of growth.
A study both of structure and of ore deposits suggests that New
Zealand, Australia, and New Guinea have had independent origins.
GROWTH OF AUSTRALASIA FROM PRE-CAMBRIAN TO RECENT TIME
Pre-Cambrian —The greater portion of Australia, which
stretches to the west of a line drawn from the southwest of Tas-
mania to the center of North Queensland,’ is composed of pre-
Cambrian schists, gneisses, granites, and allied rock types. The
dominant strike of the foliations is northwest and southeast,
approximately, with a marked tendency to show large local, or
even regional, corrugations in the eastern portion of the area. This
is well shown on David’s map accompanying his report of 19117 to
the Royal Society. It is possible that at the close of the pre-
Cambrian period in Australia the land surface extended across the
southeastern or even the eastern portion of the continent. This
is suggested, not only by the schists of Cloncurry in Northern
Queensland mentioned by Woolnough, but also by the pres-
ence of great masses of schists and gneisses of unknown age in
Eastern Victoria extending northward into the Cooma district.
2W. G. Woolnough, Bulletin of the Northern Territory, No. 4, Dept. External
Affairs, Melbourne, 1912, p. 51.
2 ‘Presidential Address,” Proc. Roy. Soc. N.S. Wales, t911. See large map
accompanying the paper. zs
UN AL
120
ee"
bye
za
gen
Yah 4
Metall he
rit Ie
aa Hh Oi
York Song,
OM ag
Lay
ae
i) { A ch» prot
Luatinye y
‘ in {imate
A, «
Dey 2
/Tpetvery yh he
t Lond
cre
rave Range
Desert
i tt tie
ayes
youth kyr’ \
olan Le 5 ~ i
|
| sdmipalty [2 O18! Matthios!
gqutin I!
lata Torre
oe Bismarck
Archies ago
pstharaday)
Keron
Siauittr
waminonr i
re Maley,
4
siqynen SEP \ Gc Dypertion
gy! of ork |, cnarlotle fey
Musa Mu Setawan ver jn? i A Alle
Cyoroate! pyich I
Cavpenthos % pe Fycyialtery- =
dptiren
poled! Giz |
pellag ylt eA gy f
al ) =
hitart } LM achat { aGdonia
opi (Frenchy
AA
“n Wo Si
NEMS
NEV aime (ireken Mid) Py»
Finder | m With
v
Port Minter
{) My W. 4 on Jackson
Te
Port Makquarte
2 ager ar pt
nya \ Vinton Pron
vw
Oe a 0 “shure a
a
car’
Macquarte
Bg NSWISL
——
of 175 Gowen Ld —
len At Leelee
va
756 E. C. ANDREWS
Browne,’ however, inclines to the belief that a portion of this
area, at least, is of Ordovician age. Other schist masses exist in
Queensland.
The possibility of sediments and other rock masses being molded
onto, or being wrapped round, these resistant blocks is thus sug-
gested.
Cambro-Ordovician.—Since the momentous pre-Cambrian period
the greater portion of the area mentioned appears to have been a
positive or buoyant element till the present day. A great negative
area appears to have existed at this time over Eastern Tasmania,
Victoria, and New South Wales. It is possible, however, that a
positive element existed in this period in Southeastern Victoria and
New South Wales. The Cambrian sediments are more in evidence
on the western strip of this area, while the Ordovician are common
on the southeastern and eastern portions. It is possible that the
Ordovician sediments of the more eastern areas are conformable to
the Cambrian, but there is an unconformity between the shallow
water forms of the two in the MacDonnell Ranges of Central
Australia.
Silurian.—At the close of the Ordovician there was a very
powerful folding movement. Wherever the Ordovician occurs in
New South Wales or Victoria, it is strongly folded and altered. The
new land surface was carried far to the north and east by this fold-
ing movement. Ordovician sediments occur quite near the coast
about 100 miles south of Sydney, and they outcrop within 120
miles (lat. 33° S.) of Sydney in a direction west-northwest. Thence
to the pre-Cambrian outcrops of the more western areas they may
be seen in many places, exposed by the stripping of their Devonian
cappings.? In the majority of the localities observed the strike of
the sediments is west of north.
During the Silurian the old negative area which had been occu-
pied by the Cambro-Ordovician sediments once more sank, and the
sea transgressed far to the west, almost to Broken Hill (long. 141°
tW.R. Browne, ‘‘The Geology of the Cooma District, N.S. Wales,” Jour. Proc.
Roy. Soc. N.S. Wales, XLVIII (1914), 172-222.
2E. C. Andrews, “The Canbelego Gold and Copper Field,” Mineral Resources,
No. 18, Dept. Mines, N.S. Wales, 1913. See maps and sections.
AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND 757
E.), not nearly so far west, nevertheless, as the Ordovician sea had
transgressed. ‘This sea was shallow in places and full of islands.
As in the Cambro-Ordovician period, sandy sediments and con-
glomerates also were deposited in the west, while great areas of
coralline limestone were deposited in the eastern portions. Much
of the area colored on the geological map as Devonian in the west
of New South Wales may be found hereafter to be Silurian or
Cambro-Ordovician in age. No fossils have been found in these
beds, and they have been referred to the Devonian because of their
lithological resemblance to the eastern Devonian quartzites and
sandstones. ‘The strikes of the sediments are similar to those of
the Ordovician.
Devonian.—A strong movement of folding closed the Silurian
and ushered in the Devonian sedimentation. The Devonian prob-
lem in Australia is complicated much in the same way as are the
Carboniferous, the Permo-Carboniferous, the Trias-Jura, and the
Tertiary. The work of the pioneer geologists suggested that there
were two, if not three, divisions in the Devonian period, with an
unconformity between two of the sets of sediment.
Mr. W. S. Dun has made a study of the Devonian in Australia
and he has supplied the following notes for this report. He states
that the Buchan and Bindi sediments in Victoria appear to be of
Middle Devonian age, and that they are the equivalents, in great
measure, of the Murrumbidgee beds in Southern New South Wales,
the two groups containing types of fossils in common. In this case,
however, Mr. Dun points out that it is probable that after
detailed examination, Lower Devonian sediments would be found
developed in these regions passing into Middle Devonian.
The Upper Devonian series of sediments are characterized by
the forms Lepidodendron australe, Spirifer disjuncta, and Rhyn-
chonella pleurodon. The Upper Devonian series occur both at
Mount Lambie and at Tamworth (New England). In the latter
locality, however, Spirifer disjuncta and Rhynchonella pleurodon do
not appear to have been found.
Sussmilch,? in dealing with the Devonian, says: “An alternative
explanation of the relations between the Lower and Upper Devonian
tC, A. Sussmilch, Geology of New South Wales, 1914, pp. 77-80.
758 E. C. ANDREWS
formations, however, suggests itself, and that is that the two forma-
tions were deposited more or less contemporaneously, the former
in an open but comparatively shallow continental sea, at some dis-
tance from a shoreline; the latter in the shallow coastal waters of
the same sea’’ (p. 80). He suggests that the marked differences
so well established by R. Etheridge, T. W. E. David, and W. S. Dun
between the faunas of the two formations would be due in such case
to the unlike environments.
To Benson’s field work, however, we are indebted for one definite
piece of knowledge which may be expected to help in clearing up the
tangle which has gathered round the Devonian in Eastern Australia.
He' showed that the Carboniferous in New England is actually con-
formable with the Devonian in that region, the sediments of each
age being strongly folded, the strike of the folding being north-
northwest approximately, as traced for 200 miles at least.
During various geological surveys in the western, southern,
and northern parts of New South Wales, the writer has noted
that the Devonian sediments vary in appearance and structure,
and the results of those observations would suggest that in very
great measure the Devonian sea transgressed the area of folded
Silurian sediments as far west as the Darling, without extending,
however, as far in that direction as had the Silurian sea. A move-
ment of folding apparently occurred in the Devonian which affected
the eastern portions of Southern New South Wales strongly, being
more marked as a whole in the northern portion of that area than
in the southern, and more marked in the east than in the west. This
movement may have been revived still later, with a tendency to
cause Australia to grow northward and eastward as it had at the
close of both the Silurian and Ordovician periods, the movement of
sea transgression to the west and south being less during each suc-
ceeding period.
This brings us to a mention of the long zone of weakness extend-
ing from a point somewhat south of Sydney to Queensland in a
direction slightly west of north. The great negative area which had
received the Ordovician and Silurian sediments had been changed
to a positive element with the close of the Devonian sedimentation
in the south and west. ‘The negative area by this time had shifted
= W.N. Benson, Proc. Linn. Soc. N.S. Wales, 1913, pp. 490-517.
AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND 759
to the position mentioned above, and such a zone of weakness
appears to mark the boundary of two geological provinces in
Eastern Australia. Benson has shown that in this heavy area the
Devonian and Carboniferous accumulated conformably, none of the
series apparently being folded until the close of the Carboniferous.
Carboniferous sediments are believed by some geologists to exist
in Australia south of this zone, but Mr. W. S. Dun, in a personal
communication, has informed the writer that in his opinion the
fossils from such sediments are to be referred to the Devonian
rather than to the Carboniferous.
It is advisable, at this stage, to consider the general scheme
of folding for the Devonian in Eastern Australia, inasmuch as what
obtains for the Devonian in a general way, as regards its structure,
is true also of the Silurian and the Permo-Carboniferous with this
difference, that the analogies of form in rocks of the various periods
considered are to be sought in areas which succeed each other to
the north-northeast approximately in succession of time. Thus if
the Silurian has been folded strongly over a large area, it may be
found that the strongest folding of Devonian might be expected
to be found north and east of the southern Silurian folds, whereas
in certain areas of the strongest Silurian folding the Devonian
is to be found bedded almost horizontally.
Thus in Tasmania the Devonian is missing; in Victoria it is
folded, apparently in two series separated by an unconformity;
in Eastern New South Wales it is strongly folded, whereas in
Western New South Wales it occurs as a series of gentle rolls and
folds, with small areas, however, exhibiting local nipping or sharp
folding within the complex basement of Cambro-Ordovician and
Silurian.” Reference to forms very similar will be made in the
chapter dealing with the Permo-Carboniferous.
It may be mentioned here that a peculiar occurrence of so-called
Devonian sediments has been recorded from Northwestern Aus-
tralia by H. V. Woodward.2 This observer mentions Devonian
E. C. Andrews, “Canbelego Gold and Copper Field,” Mineral Resources, No. 18,
Dept. Mines, N.S. Wales. See maps and sections.
2 Report on Gold Fields of the Kimberley District (by Authority), Perth, 1891, p. ro.
Quoted from T. W. E. David’s “Presidential Address,” Proc. Linn. Soc. N.S. Wales,
1893.
760 E. C. ANDREWS
sediments at Kimberley (Northwestern Australia), which are said to
possess a strike almost northeast and southwest, and a dip of 70°,
while so-called Carboniferous sediments lying immediately above
are almost horizontal.
Carboniferous.—Benson’s great contribution concerning the
conformability of the Carboniferous with the Devonian in North-
eastern New South Wales allows us to infer that the Devonian south
of lat. 33° S. was folded prior to the tilting of the New England
Devonian, and it suggests also that not only Middle Devonian but
also Upper Devonian is to be expected in this New England series.
Permo-Carboniferous—The Permo-Carboniferous period was a
most interesting one in Australia, but only the salient points dealing
with its history are here recorded so far as they deal with the main
thesis of this report.
A great period of submergence is indicated over wide areas
throughout peripheral Australia, but the strong folding to which
certain sediments of this age were subjected at the close of the sedi-
mentation was confined to a relatively narrow area within Eastern
Australia north of the Hunter River, lat. 33° S. Thus the sedi-
ments of this age in Tasmania and Western Australia are almost
horizontal; in Victoria they appear to be flexed only in the neigh-
borhood of Tertiary faults or monoclinal folds; in Southeastern
New South Wales they exhibit corrugations scarcely recognizable;
in the coastal region 100 miles north of Sydney they are moder-
ately domed,? whereas to the west and southwest they are almost
horizontal. In Northeastern New South Wales, as shown by
Carne, Woolnough, and the writer, the Permo-Carboniferous sedi-
ments are much folded and intruded by granite, whereas at a dis-
tance of 200 miles to the west the strata lie almost flat. In Southern
Queensland the Permo-Carboniferous is intensely folded, as men-
tioned elsewhere in this report.
tE. C. Andrews, “‘ Yalwal Gold Field,’ Mineral Resources No. 9, Dept. Mines,
N.S. Wales, 1901; L. F. Harper, “‘The Southern Coal Field,” Memoir No. 7, Dept.
Mines, N.S. Wales, 1916.
2T. W. E. David, “‘The Hunter River Coal Measures,’ Memoir No. 4, Dept.
Mines, N.S. Wales, 1907.
3 J. E. Carne, “Western Coal Fields,” Memoir No. 6, Dept. Mines, N.S. Wales,
1908.
AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND 761
Farther north, as, for example, at Gympie' and Mount Morgan,
the sediments are strongly folded and are Permo-Carboniferous
in age. Along the north coastal area of Queensland there is a very
long belt of sediments which are highly contorted and which appear
to be Permo-Carboniferous. Nevertheless, less than 100 miles
inland the Permo-Carboniferous‘ dips at an angle of 12° only. All
this indicates that the close of the Permo-Carboniferous period
was accompanied by a strong folding movement in areas north and
slightly east of the areas affected by the great closing Carbonif-
erous movement in New England. Additional evidence of this
is adduced when dealing with the regions of ore deposition in
Australia.
The strikes of these foldings may be considered as subparallel
to the Carboniferous lines of Benson, namely, northwest to north-
northwest.
It may be pointed out here also that the area of Permo-
Carboniferous sediments in Tasmania, South Australia, and
Western Australia is very large; nevertheless the beds there are
horizontally bedded.
Trias-Jura.—lIn this period there appears to have been a tend-
ency for the old heavy, or negative, area of Central-Eastern Australia
to sag again, or for the long zone of weakness separating New Eng-
land from the land to the west and south to be broadened. In the
northeastern portion of New South Wales and in Southern Queens-
land another area of sagging received a great thickness of Trias-
Jura sediments.
‘The geographical conditions under which the two sets of sedi-
ment were deposited differed in certain well-marked features. This
t Jack and Etheridge, Geology of Queensland (by Authority), 1892, pp. 72-84.
B. Dunstan has also produced detailed geological maps of this area in a late number of
the Queensland Survey Publications.
2 Jack and Etheridge, Geology of Queensland, p. 508.
3 Lionel C. Ball, ‘‘Wolfram, Molybdenite, and Bismuth at Bamford, Northern
Queensland,” Queensland Mining Journal, 1914, p. 568. Mr. Ball has made a more
definite statement as to the Permo-Carboniferous age of the beds in this district in a
recent communication to the writer.
4]. H. Reid, “Permo-Carboniferous at Bett’s Creek,” Queensland Government
Mining Journal, July, 1914, pp. 408-12.
762 E. C. ANDREWS
has been indicated most clearly by Carne,’ who calls attention to
the fact that massive conglomerates, coal seams, and abundant
fossil trees characterize the northern sediments as to their lower
members, while tuffs and sandstones without heavy conglomerates,
coal seams, or abundant tree stems characterized the southern and
western sedimentation (Triassic). Cross-bedded sandstones of
warm-brown color and intercalated black shales characterize
the southern, middle, or Hawkesbury series, while cross-bedded
sandstones are very common in the northern or Clarence series. In
both series the later stages of the Trias-Jura appear to be dark shales
in the main.
It is possible that the great folding at the close of the Carbonifer-
ous in Northeastern New South Wales was responsible, in great
measure, for the heavy conglomerates of the Clarence series as well
as of the Triassic of the Upper Hunter valley, and it is probable that
very high land barriers separated the two sinking areas during a
moderate part, at least, of the period. This might be expected to
have caused variations in local floras. As an example, the Clarence
series contains a characteristic fossil, namely, Taeniopteris Dain-
ireei, whereas it is absent from the Hawkesbury. On the other
hand, however, Taeniopteris Daintreei is found in the Victoria
Trias-Jura, so that Carne and others consider the Clarence to be
of different age from that of the Hawkesbury.
The southern or Hawkesbury (Triassic) area does not appear
to have been dominated to the west and south by high land, inas-
much as the adjacent and subjacent Permo-Carboniferous in those
directions does not appear to have been disturbed except by a gentle
movement of sagging. ‘The earlier period of the Trias-Jura appears
to have been one of moderate to fair precipitation, but the middle
period appears to have been subarid. In the Sydney district
massive cross-bedded sandstones predominate in these middle beds,
with relatively thin layers of dark-gray shales. In places layers of
grit and subangular pebbles are interspersed with large blocks of
these dark-gray shales, all mixed confusedly, apparently marking
J. E. Carne, “Western Coal Field,” Memoir No. 6, Geol. Survey, N.S. Wales,
1907, pp. 26-41; see also E. F. Pittman, Aun. Report N.S. Wales, 1880, p. 244. Quoted
by Carne, of. cit., p. 26.
AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND 763
periods of short-lived floods (sheet floods) which broke up the clays
and mixed them with the pebbles and grits carried downstream by
the local cloud-bursts or heavy rains. This appears also to have
been the opinion of Professor H. E. Gregory, of Yale, from an
examination by him in 1916 of the Sydney and Blue Mountain
exposures. The upper portion of the period appears to have
been one of greater precipitation in which actual lakes were in
existence.
At Sydney, and a little south of that area, the Triassic beds dip
inland at a very gentle angle, but, as Carne has shown, the whole
southern area of these sediments has a dip averaging only from 1°
to 2°. In the northeastern part of New South Wales, however, the
Mesozoic coal measures and the conglomerates dip from 10° to 20°,
while in Southern Queensland they have been still more disturbed.
In the western portions of Eastern Australia, however, as also in
Western Australia, they lie practically horizontal.
There appears to be no consensus of opinion among Australian
geologists as to the origin of the Hawkesbury beds. Rev. J. E.
Tenison Woods considered them to be of wind-blown origin’ with
lakes and swamps between the dunes.
In an unpublished paper R. S. Bonny considers them to be of
estuarine origin. On the whole they may be said to be continental
in origin, being formed in a sinking area mainly by water strains in
a rather dry period.
Cretaceous.—The Cretaceous period marked a spilling over of
the ocean with the formation of great epicontinental seas, especially
during the Upper Cretaceous period. The area most affected was
the northern portion of the old heavy area separating Eastern and
Western Australia. It is probable that, during the Upper Cre-
taceous, the epicontinental sea extended from the Gulf of Carpen-
taria to the Southern Ocean. The eastern area occupied by the
Triassic sediments, however, consisted of dry land during the
Cretaceous. At the close of the period the whole center of Australia
appears to have been raised to a moderate height above sea-level.
Dunstan and Richards have recorded pronounced folding (40°-55°)
“The Hawkesbury Sandstone,” Proc. Jour. Roy. Soc. N.S. Wales, XVI (1882),
53-90.
764 E. C. ANDREWS
of Lower Cretaceous rocks on the coast of Queensland at some dis-
tance north of Brisbane.t ,
Reference will be made later to this local evidence of folded
Trias-Jura and Cretaceous rocks along the coast of Central and
Northern Queensland.
Tertiary pertod.—The Eocene sea was not large and appears to
have been confined to areas, relatively small, in the north and south
of the continent. Indeed, the continent as a whole, except in the
northeast, appears to have been growing in size subsequently to the
close of the Cretaceous, although a submergence, postdating the
recent Glacial period, appears to have isolated New Guinea and
Tasmania from the mainland.
It is as if there has been a general tendency in Australasia and
New Zealand to move in a vertical direction in post-Cretaceous time,
the movement being subject to two great laws:
1. That elevation, or vertical movement, of the land was empha-
sized in an easterly direction, as from Western Australia to New
Zealand, due allowance being made for the lagging behind differ-
entially of the two great and relatively heavy portions, namely,
Central Australia and the suboceanic mass separating Australia
from New Zealand.
2. That the uplifts after the widespread peneplanation of the
Cretaceous period did not proceed continuously, but were saltatory
in their action, and, moreover, that the periods of time separating
these uplifts became less as the present time approached, and that,
nevertheless, the amounts of individual uplifts became greater as
the periods marking the pauses between the uplifts became less in
duration. This has given rise to great “‘valley-in-valley”’ struc-
tures owing to the interrupted work of the streams.
Thus in Australia, during what appears to be the Cretaceous
period, great peneplains were formed in the land areas lying east
and west of the Cretaceous sea, and only the hardest rock structures
remained to show the existence of former plateaus or hills. In the ~
various Tertiary divisions of time the streams carved valleys with
*B. Dunstan, Queensland Government Mining Journal, December, 1912; H. C.
Richards, ‘‘The Cretaceous Rocks of Woody Island,” Queensland Aust. Assoc. Adv.
Sci., Melbourne meeting, 1913, pp. 719-88.
AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND’ 765
widths so great as to appear as local peneplains, although they are
only very broad, shallow valleys in whose bases other broad and
shallow valleys have been excavated. The great uplifts of the
later Kosciusko period allowed the streams to form profound can-
yons which receded along these older shallow valleys. In other
words, the main Tertiary land history has consisted of repeated
elevations with stream revivals. During one or more of the Ter-
tiary divisions of time, particularly in what may be the Miocene,
the land appears to have sunk with the formation of lakelike
expanses along the stream courses and the burial, later, of deep-.
river deposits beneath basalt floods covering thousands of square
miles in Eastern Australia. This led to great modifications in
the stream drainage, but the dominating lesson of the repeated
revival of stream action must not be overlooked, the modifica-
tions due to lava floods being only an incident in the great
geographical unity of Australia in Tertiary and post-Tertiary
times.
New Guinea.—lf attention be turned, however, to the north-
eastern part of Australia, it will be found that as geological time
progressed, the area occupied now in part by New Guinea was built
to the south and west. An excellent epitome of the main features
of structure known to date has been supplied by Professor T. W. E.
David. Schists outcrop at very high altitudes along its northern
portion, while strongly folded Cretaceous Strata are reported to occur
at the highest altitudes in the north, their steep dips ending abruptly
against a high and deeply dissected plateau surface. For 50 or
60 miles inland from the south, the area consists of middle and late
Tertiary strata, all intensely folded, and all beveled off by a high
plain, probably one of submarine erosion. The knowledge of this
strong orogenic movement in late or closing Tertiary time and the
excavation of a plain of erosion within folded sediments of this age
was established by Carne while doing pioneering work in the oil
industry.”
t “Geology of Papua” (Federal Handbook), Brit. Assoc. Adv. Sci., Australian
meeting, 1914, pp. 316-25.
2J. E. Carne, Bull. of the Territory of Papua, No, 1, Dept. External Affairs,
Melbourne, 1913, pp. 19-29.
766 E. C. ANDREWS
David’s conclusion is:
In regard to the broad tectonic features of Papua it may be suggested,
very tentatively, that the mainland of Australia has functioned as a “foreland
massif,” Torres Straits, the Gulf of Carpentaria, the Arafura Sea, and the deep
Mesozoic and Tertiary basins with their thick strata as a Senkungsfeld. Pos-
sibly the crystalline schists forming a great part of the backbone of the island
have played the part of an inner, or riick-land massif which has helped to roll
up the Mesozoic and Tertiary sediments.
In passing, it may be mentioned that this simply raises the
question again as to the origin of the forces of crumpling. Do they
act from the land as suggested by Suess in his discussion of the
Asiatic framework, or do they act from the oceans? If the move-
ments be assumed to act as from Central Australia toward the
oceans, then it is difficult to understand the stability and rigidity of
such central area of force. If the source of energy is suboceanic and
directed toward the continents, then it is difficult to explain the
growth of Australia north and east, while that of New Guinea
appears to be south and west, unless, indeed, it be assumed gratui-
tously that the later foldings in Northeastern Australia are simply
the expressions of orogenic movements dying away in a south-
westerly direction from the Pacific. Even so the intense contor-
tions evidenced in the Miocene and Pliocene beds might be expected
on the northeastern aspect of New Guinea rather than on the
south and southwestern. It would seem, indeed, as though each
negative or heavy area had played a part in the movements.
New Caledonia—In New Caledonia the Mesozoic sediments
have been intensely folded, especially on the western and south-
western aspects, and the overfolding appears to have been directed
toward Australia, according to Peletan, Depiet, Piroutet, and
others as quoted by Suess.?__
New Zealand.—In turning to a consideration of New Zealand we
meet with a certain amount of disappointment, inasmuch as there
is no consensus of opinion among the workers on certain funda-
mental points. Thus a glance at Dr. J. W. Gregory’s map in the
article on New Zealand in the eleventh edition of the Encyclopaedia
tT, W. E. David, “Geology of Papua,” op. cit., pp. 324-25.
2 Die Antlitze der Erde (Eng. tr.), IV, 314-15.
AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND 767
Britannica suggests that this island group was built principally as
from southwest to east and north, or at any rate that with the prog-
ress of geological time folding movements retreated to the north
by east. Marshall, however, in a personal communication, under
date of April, 1916, states that much of the New Zealand Jurassic
has been confused with the Maitai (so-called Carboniferous) by
older workers. Marshall, however, adduces sound reasons for
considering New Zealand as being the true boundary of the Pacific
Ocean‘ in that portion of its area. Cotton in a recent paper states
that the “most profound deformation of this vast sedimentary
group [Paleozoic and Mesozoic] took place in Later Jurassic or
Early Cretaceous times.”? He also states that the average trend
of the strike of this older mass appears to be west of north (p. 245).
And again he writes: “It is apparent that during the period of their
deposition [that is, the Tertiary Andes] a great part of the site
of the present islands of New Zealand was continually submerged”’
(p. 247). 2
Cotton also speaks of orogenic movements in the Pliocene in the
northern and more eastern portion of the group, and it is known,
moreover, that great volcanic activity has taken place in the
northeastern portion of the group with the formation of important
gold deposits.
In a personal communication dated August 22, 1916, Cotton
writes:
The early geological history [of New Zealand] is much obscured by the
later happenings—a great deal more so, it would appear, than is that of
Australia. We cannot even be sure that we have any considerable area of
Paleozoic rocks. The small areas of Ordovician and Silurian in northern
Nelson we can be certain of, but we know nothing whatever of the relations of
these, either to each other or to rocks of later Paleozoic or Mesozoic age. It is
the opinion of the present director of the Geological Survey that the greywacke
rocks extending southward along the West Coast are of Aorere (Ordovician)
age; but they contain no paleontological evidence of age and are part of the
“Maitai” system of other writers. As for the ‘‘Maitai” rocks throughout
tP, Marshall, “Presidential Address,” Geological Section Aust. Assoc. Adv. Sci.
Sydney, XIII (1911), 90-99.
2 ‘“‘ The Structure and Later Geological History of New Zealand,” Geol. Mag. Lon-
don, No. 624, June, 1916.
768 E. C. ANDREWS
New Zealand, there seems to be no reason now for classing them as Paleozoic.
As regards the Manapouri rocks of southwestern Otago, they may, of course
(with the exception of some intrusives), be very ancient; but their relations to
other systems are absolutely unknown. It may be that this is an upfaulted
block from which a Mesozoic cover has been removed. So far as I know there
is no evidence of later formations having been folded against it.
The remarkable flat-lying schists of central and eastern Otago are, again,
of indefinite age. Marshall regards them as metamorphosed Mesozoics.
He traces a transition to the unaltered ‘‘ Maitais,”’ but in eastern Otago, along
the junction of the schist and greywacke rocks there is a complex of faulted
blocks (greywacke now forming the surface in some and schist in others) which
had, there can be no doubt, been planed down before the deposition of what I
call the ‘‘covering strata.” Later faults, which affect the cover also, have
sometimes followed the lines of the older breaks, but have reversed the throw.
As to the direction of folding in New Zealand I have formed no opinion.
The latest or Kaikoura folding was accompanied by the formation of great
reverse faults in the northeastern part of the South Island, and these hade to
the northwest. Many small reverse faults in the Wellington neighbourhood,
which intersect (?) Triassic rocks and were perhaps developed during the
Mesozoic period, hade in the same direction.
One question of great importance is that of the source of the enormously
thick ‘‘Maitai’”’ sediments, which consist, from end to end of New Zealand,
almost universally of the little-worn detritus from acid igneous rocks. Evi-
dently these deposits accumulated not far from a great land mass, but I know
of no evidence as to the position of that land mass. Apparently the New
Zealand area sometimes formed a part of the continent, for at a number of
places there are deposits containing Mesozoic plants.
So far as I know there was no strong folding accompanying the formation
of the Hauraki gold deposits, but there have been considerable “block”
movements since.
EVIDENCE OF THE ORE DEPOSITION
It is proposed here to see what light may be thrown on the
possible structural relations or differences of Australasia, New
Guinea, and New Zealand, by a study of the peculiarities of ore
deposition in certain areas within these regions. In this connection
it is proposed to deal principally with one set of minerals only,
namely, the tin group, although conclusions equally interesting
would have been forthcoming from a consideration of the gold and
copper, together with the silver-lead and zinc groups.
Thus with regard to gold it would have been possible to elaborate
with a wealth of detail the knowledge that the gold deposits of
AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND 769
West Australia are found in the great area of pre-Cambrian rocks
there developed, and, moreover, that they occur in belts arranged
more or less parallel and relatively narrow in width, although in
certain localities they appear as small isolated areas or patches;
that these narrow and well-defined belts have a general northwest
and southeast direction, with divergences in certain instances of
several degrees on either side of this direction; that the ore deposits
in these belts or zones, owing to certain activities, do not crop out
in long and unbroken lines, but are cut up into relatively short
lenticles, arranged en echelon.
Table I gives the approximate values of the several metals mined
in these countries.
TABLE I
v
APPROXIMATE TOTAL VALUES, IN MILLIONS or PouNDS STERLING, OF THE MorE
Important Metats MINED IN AUSTRALASIA AND NEW ZEALAND
Gold Copper Silver Zinc Tin | Wolfram | Bismuth Pate
West Australia..| 73.00 | II.00 |.......|....... TROOUM EN sceage ell oeee ae opera] ones ee
North Merritony.|>) 2:10) |) ©.20) |... . esc] oe... Ov sslelONOAe lige sake ni Grp cease
Sowa Amelie. || se.Croy | o,ero I" Menai} [bibaig o4 llace do oclsoaucdcledecosolloucoane
Tasmania....... RoGe || Wi GO | Ooo! loco ous T/2)500})|) OnOSi lO. O2N| eae ciee
Wictoriay.)s)..2 4. BOOROOM ON 2I5iiI| NhOsOOO| neice = Or SO OOS |e. kate alee reee rte
New South
Wales........} 62.00 | 13.50 | 74.00 | 12.00 | 10.50 | 0.25 | 0.166] 0.10
, Queensland..... SOnCOM rT SON | 2)425) ||leleysvers 8.50) | 10.80) | ont25|) Ons
iINewsZealand eee |MSicHooi MOOD ills Saks tas. teal peiee Vacs es [oust ciel iseetaess teenies
The general direction of these auriferous belts almost everywhere coincides
with the strikes of the schists, which, with one or two exceptions, invariably
form the matrices of the gold-bearing reefs. ... . The quartz reefs are of two
distinct types, namely, white quartz reefs and laminated quartz and jasper
veins approaching very closely the hematite-bearing quartzites which invari-
ably form a conspicuous feature in most of the gold fields of the State. Some
of the laminated quartz veins range from almost-pure quartz, through banded
jaspers, with crystals of magnetite, to bands appearing to the eye to be vir-
tually pure haematite. The quartz reefs, of what may be called the massive
types, occur plentifully in both the schists and the granites.t
Like the gold deposits of Western Australia those of the North-
ern Territory and of South Australia appear to be pre-Cambrian
tA, Gibb Maitland, ‘“‘Mining Fields of Australia” (Federal Handbook), Brit.
Assoc. Adv. Sci., Australian meeting, 1914, pp. 447-48.
770 E. C. ANDREWS
in age, although there are certain indications of relative youth in
the gold deposits of the Northern Territory and South Australia.
Eastward, in the old trough lying within New South Wales and
Victoria, now filled with Cambro-Ordovician and infolded Silurian
sediments, occur the most important gold deposits of Australasia,
especially the famous saddle reefs of Bendigo, Ballarat, Canbelego,
and other localities. Immediately to the east and north lie the ore
deposits beyond the Hunter zone of weakness where Benson’s line
of serpentine occurs with its gold deposits of Carboniferous age.
Beyond, but parallel, or subparallel, with these, are the great gold
fields of the closing Paleozoic period in New England and Eastern
Queensland, as, for example, at Hillgrove, Gympie, Mount Morgan,
and the Palmer. It might be mentioned that, although no gold
deposits appear to have been formed in Australia since that momen-
tous period, nevertheless the important gold deposits of the North
Island of New Zealand are of late Tertiary age. It might be men-
tioned here that the gold deposits of Southwestern New Zealand
appear to occur in Paleozoic rocks.
Or it would have been interesting to enlarge upon the facts
connected with the copper deposits of Australia: how in the
west they are of pre-Cambrian age, according to Maitland and
his geological staff; how the nature of the deposits there suggests
deposition at a great depth below the old land surface; how the
copper deposits of great but of unknown age, in the Northern
Territory, South Australia, Western New South Wales, and Tas-
mania, as, for example, at Wallaroo, Moonta, Burra Burra, Cobar,
Nymagee, and Mount Lyell, do not appear to be dependent upon
ordinary igneous rock types, but, from an examination of the reports
of Ward, Jack, J. W. Gregory, and the writer, they appear to be the
equivalents themselves of igneous rocks because of their peculiar
mineral assemblages; how with these famous deposits might be
mentioned the great Broken Hill deposit of silver-lead and zinc
which is apparently a replacement of schists by garnet, rhodonite,
feldspar, and sulphides, owing to the action of vapors arising along a
shear zone; how the arrangement en echelon of these metalliferous
areas and the individual ore lenses within such areas must be sig-
1 E. C. Andrews, “Broken Hill Lode,” Economic Geology, October, 1908, pp. 643-45.
AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND 771
nificant in the extreme. It would be instructive also to tell how,
in New England, the copper and the gold which were introduced
during the Carboniferous folding of Benson occur in the same
deposits as a rule, as also do those of the closing Paleozoic both in
New England and in the more coastal portions of Eastern Queensland
(examples, Drake and Mount Morgan); how also in the Carbon-
iferous of New England the copper and gold depend upon the ser-
pentine belt for their existence, whereas in the Permo-Carboniferous
they are related to lamprophyric dykes and basic granitic types.
In New Guinea the copper deposits appear to be in very ancient
rocks, whereas in New Zealand copper is practically absent.
The tin group of minerals—Turning, however, from these inter-
esting points to the tin-wolfram—molybdenite-bismuth group of
minerals in Australia, it may be noted that all four may occur
together in certain ore deposits in this continent, but as a rule the
deposits of commercial importance may be classed under two main
heads. Thus tin is frequently associated with wolfram, whereas
molybdenite is associated with bismuth. Should molybdenite and
bismuth be associated with other minerals of the group, the prefer-
ence is for wolfram rather than for tin. Indeed, the minerals asso-
ciated with tin and wolfram, such as tourmaline, topaz, beryl, and
quartz with rutile, are practically unknown to the writer in con-
nection with molybdenite deposits.
All these minerals in Australia—tin, wolfram, molybdenite,
and bismuth—are associated with siliceous granites or their equiv-
alents. In New South Wales the typical tin-wolfram granites range
from 75 to 79 per cent silica, while the typical molybdenite-
bismuth types range from 72 to 74 per cent silica. These various
granites may be distinguished easily by their peculiar vegetation,
and appear to have been the hosts of the tin-molybdenite minerals
in Australasia. The vapors which conveyed the minerals of the
tin group to the marginal portions of the granites, preferably the
roofs, or upper and lateral portions, appear to have varied in their
power of penetration. Thus the tin and wolfram deposits, with
their boric and fluoric associates, are found in many places at slight
distances from the siliceous granites themselves, in rocks such as
slate, basic igneous rock, or quartz-porphyry. Always, however,
T72 E. C. ANDREWS
the tin minerals may be seen to be intimately related to the siliceous
granites. The molybdenite deposits are almost always within
the marginal development of the siliceous granites, while tourmaline,
topaz, and allied minerals are characteristically absent. Contact
deposits of molybdenite in Australia, as, for instance, at Yetholme
(New South Wales), are rare.
Although these granites in Australia accompanied strong
folding movements, and although ore deposits in that continent
appear to have been dependent upon strong folding phenomena,
nevertheless it must not be inferred that all periods of folding in
Australasia have been associated with the formation of ore deposits
on a commercial scale, but simply that all ore deposits of com-
mercial importance in Australasia are intimately related in some
way to periods of folding. This statement refers, naturally, only
to deposits of the metallic minerals.
a) Western Australia: The vast area of Western Australia con-
sists, In the main, of highly altered rocks of pre-Cambrian age.
These schists and allied types are intruded by siliceous granites
and allied rocks, which also are considered to be pre-Cambrian in
age. ‘‘The old granite rocks are traversed by many large ice-like
Quartz) Feels.9.5. a: These older granite rocks ... . . formithe
matrices of the tin and allied deposits of the state.”
This mineral has been found to the extent of about 14,000 tons in
Western Australia, while wolfram is subordinate in amount.
Molybdenite has been recorded in small scattered flakes from this
area.
b) Northern Territory: The rocks of the Northern Territory are
extremely old, probably pre-Cambrian in many places. Tin and
wolfram to the values respectively of £400,000 and £40,000 approxi-
mately have been won from the Northern Territory. Molybdenite
has been reported, but it has not been worked as yet.
c) South Australia: The ore deposits of South Australia
are very old. Tin, wolfram, and molybdenite have been found
in this state, but the amounts won are too negligible to be
considered.
tA. Gibb Maitland, “Mining Fields of Australia” (Federal Handbook), Brit.
Assoc. Adv. Sci., Australia meeting, 1914, pp. 446-47.
AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND 773
d) Tasmania: The tin, wolfram, molybdenite, and bismuth
deposits of Tasmania are considered to be of closing Silurian or
early Devonian age.’
The tin production exceeds £12,000,000 and the wolfram
£50,000 in value. Molybdenite has not been worked, but bismuth
to the extent of about £200,000 value has been won.
e) Victoria and Southeastern New South Wales: In Victoria
the age of the tin, wolfram, molybdenite, and bismuth deposits
is not known definitely. The value of the tin won is slightly
less than £1,000,000, that of the wolfram about £5,000, while
molybdenite and bismuth have been found only in very small
quantities.
Probably Victoria and Southeastern New South Wales form |
one geological province, and in the latter area the tin and allied
minerals may be considered as of post-Devonian and of pre-
Permo-Carboniferous age. ‘Tin is relatively rare, but molybdenite
and bismuth are abundantly represented.
f) Northeastern New South Wales and Eastern Queensland:
The northeastern portion of New South Wales appears to be a
province geologically distinct from that of the southeastern portion
of the state, and the tin, wolfram, molybdenite, and bismuth
deposits found there appear to be closing Paleozoic in age. These
deposits are confined to a strip less than 150 miles from the coast.
The commercial molybdenite and the bismuth occur within
the eastern zone, while the commercial tin occurs within the
western .zone. The small deposits of the far west, near Broken
Hill, for example, apparently are of very early Paleozoic
age, and they really belong to the South Australian region or
province.
The value of the tin won from New South Wales exceeds
£10,500,000, the wolfram values approximate £200,000, the bis-
muth £150,000, and the molybdenite about £100,000.
In this connection it should be remembered that until 1902
molybdenite was considered as an impurity in the bismuth, its
=W. H. Twelvetrees, “The Scamander Mineral District,” Bull. No. 9, Geol.
Survey, Tasmania, 1911, p. 23-24; other official reports of great interest dealing with
the subject of mineral deposits in Tasmania are by L. K. Ward, Loftus Hills, and
L. L. Waterhouse.
774 E. C. ANDREWS
inseparable associate in New South Wales; thus great amounts of
the molybdenite have been lost.
Queensland, in its eastern portion, should be considered as
belonging, probably, to the same geological province as New
England, or Northeastern New South Wales.
The tin, wolfram, molybdenite, and bismuth deposits are found
only within the eastern strip of the state, and their age appears to
be the close of the Permo-Carboniferous. The granites and mineral
associations of the two areas are almost identical also. Thus this
great province of Eastern Queensland and New England, which has
yielded the bulk of the world’s supply of molybdenite, lies on a great
flat arc having a general trend of northwest to north-northwest.
These ore deposits are associated with strong movements of folding,
the age of which appears to be closing Paleozoic.
The approximate values of the tin, wolfram, molybdenite, and
bismuth won from Queensland are respectively £0,000,000 to
£10,000,000, £1,000,000, £250,000, and £150,000.
It would thus appear that the deposits of the tin and molybdenite
group of minerals in the great geological province of Western
Australia, South Australia, and the Northern Territory are of
great age, but that they are almost negligible in commercial value.
It is not known, however, what proportion of this absence is due to
removal by erosion of the upper portions of the granites. The
deposits of this group in Tasmania may be of closing Silurian or
early Devonian age, the tin values ‘being very large, but wolfram,
molybdenite, and bismuth are unimportant; the deposits of the
geological province of Southeastern Victoria and Southeastern
New South Wales are important and are post-Devonian and
pre-Permo-Carboniferous in age; while the deposits of the prov-
ince of New England and Eastern Queensland, forming a coastal
fringe to Northeastern Australia, are highly important from a
commercial point of view and appear to be closing Paleozoic
in age.
t Official reports have been written on the tin and molybdenite areas of New South
Wales by T. W. E. David, J. E. Carne, and the writer, while Professor Leo A. Cotton
has published reports on the tin of New England in the Proc. Linn. Soc. N.S. Wales
XXXIV (1909), 738-81; Cotton intends to continue the study of tin genesis in
Australia in the near future.
AUSTRALASIA, NEW GUINEA, AND NEW ZEALAND 775
All of these Australasian deposits are intimately related to strong
movements of folding, accompanied by intrusions of very siliceous
granite.
No molybdenite, bismuth, wolfram, nor tin of any commercial
importance whatever appears to have been found in New Guinea,
New Caledonia, or New Zealand, although molybdenite and allied
minerals have been recorded as curiosities in older Paleozoic granites
in New Zealand. Neither are there in New Zealand any important
copper deposits similar to those which are so intimately associated
with the gold, tin, and molybdenite in Australasia.
CONCLUSION
It is therefore permissible, perhaps, to infer that each of the
three great groups, namely Australia, New Guinea, and New
Zealand, is a distinct geological province, but whereas in New
Guinea the movements appear to have opposed the Australian
growth with a tendency to fill the intervening negative area; on the
other hand the growth of Australasia and New Zealand appears to
have been intimately related in some manner, as though each had
grown sympathetically in response to some simultaneous dominat-
ing agency. The folding action ceased in the Australasian area
long before it did so in the New Zealand area. The foldings in
New Guinea also were maintained right into recent geological
time.
Here again the ore deposits proclaim the independence of the
three centers. The oil fields of New Guinea suggest the Burmese
or Malaysian origin of the New Guinea lines of structure,’ and in a
similar way the tin-wolfram—molybdenite-bismuth group of miner-
als appears to mark the real limits of Australasia. A little of the
molybdenite group occurs in the New Zealand area, in the very old
rocks, but the group as a whole, with its grand suite of siliceous
granite horsts, may be said to end at the east side of Australasia.
Moreover, as the folding movements retreated east and west, with
progress of time they appear to have passed away finally to the
northeast from Southwestern Australia toward New Caledonia.
tT, W. E. David, ‘Geology of Papua” (Federal Handbook), Brit. Assoc. Adv.
Sci. Australia, 1914, p. 320.
776 E. C. ANDREWS
It is therefore permissible, perhaps, to infer that the Tasman Sea
is of great age, especially in its more southern portions, inasmuch as
it appears to have been a barrier to common or related ore deposition
between Australasia and New Zealand through the ages.
This of course does not imply that Australasia and New Zealand
have not been closer together in the past, nor that Australasia has
not extended considerably farther to the east in former times,
especially in its northeastern portions; it simply suggests that some
great agency which controlled the growth of Australasia and New
Zealand appears to have admitted a negative or relatively sunken
area from early times in the region of the Tasman Sea, and that this
agency had faded away to epeirogenic movements in the Austral-
asian area while yet it was vigorously folding the New Zealand
rocks.
All this appears to be in harmony with the general contention
of Marshall* who maintains that New Zealand, and not Australia,
lies on the real border of the Pacific. Marshall, however, approaches
the subject from a point of view entirely different from that taken
in the present note.
tP, Marshall, ‘Presidential Address,” Geological Section, Australian Assoc. Adv.
Sci. Sydney, XIII, (1911), 90-99.
A BOTANICAL CRITERION OF THE ANTIQUITY
OF THE ANGIOSPERMS
EDMUND W. SINNOTT
Connecticut Agricultural College
As to the origin of the angiosperms, that group of seed plants
which is now such a dominant element in the earth’s vegetation,
we know almost nothing. They first appear as fossils in the deposits
of the lowest Cretaceous in eastern North America, Alaska, Green-
land, and Portugal, but just where they actually originated, and
how long ago, are still matters of great uncertainty. The aim of
the present paper is to throw a little light on the antiquity of this
great plant group by studying the rate of evolution displayed by its
members. |
Evolution has not been a uniformly rapid process. The fact
that plants recognized as “primitive”? and others recognized as
“recent’’ exist together at the present time makes it evident that
certain vegetable types have changed but little throughout long
geological periods, whereas others have for one cause or another
become altered much faster. The degree of inherent ‘“variability”’
and the frequency of hybridization have doubtless been influential
in determining this rate of change, but a more important factor
perhaps than either seems to be the length of the generation or
period from seed to seed. A plant in which this cycle is completed
in a year or two is able to multiply its generations more rapidly,
and thus to accumulate heritable changes much faster, than one
which requires a longer time for the attainment of reproductive
maturity. This length of generation is definitely correlated with
the growth habit of the plant, being greatest in trees—which
usually reach an age of from fifteen to twenty years (in many
cases much more) before bearing fruit—less in shrubs, and shortest
of all in herbs, where one or two seasons from seed suffice to
produce a fruiting plant again. Ina given length of time, therefore,
777
778 EDMUND W. SINNOTT
a herbaceous species will pass through a much larger number of
generations than a woody one, and will consequently tend, other
factors being equal, to become changed in type much more rapidly.
We should thus expect the herbaceous element in the vegetation
to have been evolved at a much faster rate than the woody element.
The establishment of this as a fact, taken with what we know as
to the history and present numerical status of herbs and woody
plants, will provide us with a valuable clue as to the antiquity
of the angiosperms.
That herbs are indeed subject to more rapid changes than any
other plant type is indicated by the fact that the first local species
and genera to develop in a region subsequent to its isolation have
apparently almost always been herbs. This is well illustrated by a
comparison of the floras of temperate North America and of Europe.
On these continents today there are many local or ‘‘endemic’”’
genera which are limited in their distribution to one or to the other.
Certain of these are evidently “‘relict’’ endemics, isolated survivors
of types once much more widely disseminated. They may be
recognized from the fact that they stand without near relatives
in the floras; and many of them, such as sassafras and hickory,
occur as fossils on both sides of the Atlantic. These relicts doubt-
less constitute a very ancient floral element, and it is significant
that among them are practically all the genera of trees and shrubs
which are local to either North America or Europe. The majority
of the endemic genera, however, seem to belong to quite a different
category, for they occur in groups of from three to twenty genera,
the members in each of which are closely related to one another,
each group apparently to be looked upon as a separate center of
evolution and the nucleus of a new family. The genera centering
around Lesquerella in the Cruciferae, around Eriogonum in the
Polygonaceae, around Godetia in the Onagraceae, around Pent-
stemon in the Scrophulariaceae, and around Solidago in the
Compositae, are a few of the sixty or more such groups in the dicoty-
ledonous flora of North America, and there are as many in Europe.
These “indigenous”? endemic genera most probably had their
origin on their respective continents, since a free interchange of
plants between America and Europe was interrupted, presumably
THE ANTIQUITY OF THE ANGIOSPERMS 779
in the Early or Middle Tertiary; for had they existed before that
date in anything like their present numbers and importance, it is
highly unlikely that they would now be represented in the floras
of both hemispheres. During the time since the isolation of the
two continents, and while the rest of the flora have remained
unchanged or have been developing endemic species merely, these
plants have evidently undergone much wider changes, until they
have finally given rise to new generic types. We are thus forced
to conclude that the indigenous endemic genera constitute the
most rapidly evolving members of their flora; and it is significant
that they include practically nothing but herbaceous species—
surely excellent evidence that the herb changes in type more rapidly
than the tree or the shrub.
Further evidence pointing to the same conclusion is presented
by a study of the distribution of herbs and of woody plants in the
modern scheme of botanical classification, for herbs are found to
occur in larger groups than woody plants, their genera containing
more species and their families more genera. Monotypes and
very small genera and families are very much less common among
herbs than among woody plants. These facts are what one might
expect on the supposition that herbs are changing faster than the
rest of the angiospermous vegetation, for the more rapid production
of new forms leads to the building up of larger aggregations, and
enables genera or families which have become reduced in size
through extinction to repair these ravages quickly.
A study of the structure, distribution, and ancestry of herba-
ceous angiosperms’ indicates that they have been evolved in com-
. paratively recent times from a woody ancestry, and have undergone
practically their whole course of development since the beginning
of the Tertiary. As opposed to this rapid change among herbs,
we know from fossil evidence that very many woody genera have
existed with very little alteration for a much more extended period
than the length of the Tertiary—a convincing demonstration of
the slowness with which trees and shrubs undergo evolutionary
change. Almost all our woody genera bear evidence, in present
IE, W. Sinnott and I. W. Bailey, ““‘The Origin and Dispersal of Herbaceous
Angiosperms,”’ Annals of Botany, XXVIII (1914), 547-600.
780 EDMUND W. SINNOTT
distribution or fossil remains, of a considerable degree of
antiquity.
To corroborate this testimony as to the relative rapidity of
evolution in herbs and in woody plants, data as to their actual
rate of change today would be highly desirable; but this is very
difficult to obtain. As far as differences in ‘‘variability,” using
the term in its broadest sense, are concerned, the two growth
forms seem nearly equal. In both there are many highly variable
types and many of great constancy. In the floras of three repre-
sentative regions—Eastern North America, Australia, and Ceylon—
the proportion of varieties and named forms among the woody
species is found to be practically the same as among herbs. Nor
is there a radical difference between the two in the extent of cross-
pollination by insects, although in temperate regions this is some-
what more common among herbs than among trees and shrubs.
The difference in length of generation to which we have called
attention is probably the most important factor in determining
the rate at which they have evolved.
To whatever cause we may attribute it, however, there seems
to be little doubt that during the evolution of the angiosperms
the primitive, woody element has been developed very much more
slowly than the more recent, herbaceous one; and it is this differ-
ence which gives us a hint as to the antiquity of the whole group.
We find in the angiosperm flora today (dicotyledons alone con-
sidered) over 4,200 genera of trees or shrubs, as opposed to only
2,600 genera of herbs. We may be reasonably sure that practically
all of these 2,600 genera of herbs have been developed since the
beginning of the Tertiary; and if we assume that herbs are pro-
ducing new types only twice as fast as trees and shrubs—surely a
conservative estimate—we must believe that only about 1,300
woody genera have been evolved during the same time. The
evolution of the 4,200 genera of woody plants at present existing,
to say nothing of the great numbers which have been lost through
extinction (by which trees and shrubs have suffered much more
than herbs), would therefore require a period at least thrice the
length of the Tertiary. If the common assumption that the
Tertiary was approximately as long as the Cretaceous is correct,
THE ANTIQUITY OF THE ANGIOSPERMS 781
the origin of the angiosperms would thus be thrust back to a date
much earlier than the beginning of the Cretaceous.
Of course such an estimate is hypothetical in the extreme; but
by indicating that the history of the woody members of the group
extends back over a period many times as long as that during which
herbs have existed, it serves to give us a clue as to angiosperm
antiquity, and it emphasizes the fact that our present huge array
of trees and shrubs, types very slow in changing, must have required
an enormous length of time for their evolution. There is evidence,
moreover, that evolution took place even more slowly in former
times than it does at present, since flower-loving insects, to the
agency of which many attribute the rapid development of the
angiosperms, did not appear on the scene, at least in numbers, till
the dawn of the Tertiary.‘ All this makes it highly probable that
these now dominant seed plants did not begin their existence in the
early Cretaceous, where they first appear as fossils, but that they
had already undergone a long course of evolution before that time.
Indeed, the external features, and more particularly the internal
anatomy, of these earliest fossil angiosperms are not at all those
of primitive types, but exhibit a considerable degree of specializa-
tion.? To regard such plants as having sprung suddenly into being
from gymnospermous ancestors is to overtax the imagination of
even an ultra-mutationist.
As to why the earliest members of the group apparently failed
to be preserved we cannot be sure, but evidence is at hand that
they were upland forms which would tend less frequently to become
fossilized. This predilection of primitive angiosperms for an equa-
ble, reasonably cool climate, if it can be proved, will lead us to look
back to the era of low temperatures in the Jurassic, or perhaps
even to as remote a period as the cataclysmic refrigeration of the
Permian, for the date when the first angiospermous stock began
to be differentiated from its gymnospermous ancestry.
The botanical evidence is therefore overwhelmingly in favor of
the conclusion that angiosperms existed for a considerable period
t Handlirsch, Die fossile Insecten.
2M. C. Stopes, ‘‘Petrifactions of the Earliest European Angiosperms,” Phil.
Trans. Royal Society, B, 203, pp. 75-100.
782 EDMUND W. SINNOTT
previous to the Cretaceous, although this cannot be said to be
absolutely proved till they are brought to light as fossils from the
earlier periods of the Mesozoic, a discovery which diligent search
may reasonably be expected to yield. The establishment for the
angiosperms of an antiquity greater than that usually accorded
them at the present time will be of some importance geologically,
since the occurrence of fossil members of the group in a given
formation will no longer be regarded as a demonstration of the
post-Jurassic age of the latter.
ARE THE “BATHOLITHS” OF THE HALIBURTON-
BANCROFT AREA, ONTARIO, CORRECTLY
NAMED?
W. G. FOYE
Harvard University
The large areas, composed essentially of banded red gneiss,
which are found throughout the Haliburton-Bancroft area have
been called by Adams and Barlow “‘batholiths.”* These appear
on maps of this region as circular or oval masses more or less com-
pletely surrounded by sediments or schists of sedimentary origin.
The stratification of these sediments follows in strike the boundaries
of the adjacent gneiss. Moreover, within the gneissic areas are
layers of amphibolite or gray gneiss which conform in dip and
strike to this same boundary. ‘The gneissic areas, therefore, may
be described as domes of red granite gneiss containing gray gneiss
and amphibolite in layers striking concentrically to points more or
less fixed within the mass and dipping quaquaversally at angles
which vary from 37° to 45°.
In his earlier writings, F. D. Adams stated three views as to
the origin and method of emplacement of the ‘Fundamental
Gneiss.”’
1. The Fundamental Gneiss may be the remains of a primitive crust
which was penetrated by great masses of igneous rocks and subjected to suc-
cessive dynamic movements. The Grenville series may be an upward con-
tinuation of the Fundamental Gneiss under altered conditions, marking a
transition from a primitive crust to normal sediments.
2. The Grenville series may be considered as distinct from the Funda-
mental Gneiss and reposing on it unconformably, being a highly altered series
of clastic origin; the Fundamental Gneiss having some such origin as sug-
gested above or being an older intrusive series of still more highly altered
sediments.
3. The fundamental Gneiss may be considered as a great mass of eruptive
rock which has eaten upward and penetrated the Grenville series, while the
1 Geol. Surv. Can., Mono., VI (1910), 12.
783
784 W. G. FOVE
Grenville series represents a series of altered sediments of Laurentian, Huro-
nian, or subsequent age."
Adams in the same article stated that the last hypothesis was
untenable.
The world-wide distribution of the Fundamental Gneiss (forming, as it
does, wherever the base of the geological column is exposed to view, the founda-
tion upon which all subsequent rocks are seen to rest) is opposed to this view
as is also its persistent gneissic or
banded character.?
Later, in 1897, Adams altered
his earlier view. He writes:
The batholiths are undoubtedly
formed by an uprising of the granitic
magma from below, and these foci
indicate the axes of greatest upward
movement. ‘These centers are not all
areas of most rapid uplift, however.
On the contrary, the gneissic foliation
in some cases dips inward in all direc-
tions toward the center, thus marking
them as places where the uprise of the
magma was impeded, that is to say,
places where the overlying strata have
sagged down into the granite magma.3
Fic. 1.—Map of the corundum syneite
district of Craigmont, Ontario. A striking fact concerning
Black, limestone; white, amphibolite; these so-called batholiths is that
dashed, gneissic granite; dotted, gneissic
granite with amphibolitic inclusion. they do not cut across the struc-
ture of the invaded rocks, a
fundamental characteristic by which post-Cambrian batholiths are
recognized. While it is true that there are bodies within the district
which cut across the structure of the country rock, they are unusual,
and concordant relationships are much more common.
A glance at the map (Fig. 1) which shows the corundum
syenite district of Craigmont, Ontario, makes clear the concentric
arrangement of the sedimentary rocks within the gneiss areas.
t Journal of Geology, I (1893), 330-32.
2 Op. cit., 332. 3 Am. Jour. Sci., III (1897), 173-80.
“ BATHOLITHS” OF HALIBURTON-BANCROFT AREA 785
The granite was intruded between the layers of limestone. As
in the present case, long narrow layers of limestone are often
found isolated in the gneiss. These layers are in parallel bands
and the strike of their stratification conforms to the strike of the
gneissic structure of the surrounding granite.
If the boundary between gneiss and pure limestone is sought,
it will invariably be found that there is a transitional contact zone.
The distinction between areas which may be designated as “‘ Gneiss
with amphibolitic inclusions” or ‘‘Amphibolite” or ‘Limestone
invaded by much gneiss” depends upon the degree to which the
granite has invaded the limestone and altered it to amphibolite.
In general, on crossing the strike from limestone to amphibolite,
there is a gradual transformation of one rock into the other. The
amphibolite in turn is transitional to red gneiss through the inter-
mediate stage of gray gneiss. Xenoliths of amphibolite within
the gneiss are in no degree so abundant as stringers of amphibolite
varying from a few centimeters to a meter in diameter and the
schistose structure of which conforms to the gneissic structure of
the granite and the stratification of the limestone.
Adams’ attributes the parallel arrangement of these bodies to
movements of the granite after mtrusion. He conceives that the
limestone blocks, stoped from the roof of the batholith, were
softened by heat and pulled out into lenses by flowage.
The parallel banding of pre-Cambrian rocks is not a local fea-
ture, illustrated only in the rocks of the Haliburton-Bancroft area.
_ It is, rather, characteristic of most pre-Cambrian terranes. The
interbanding of gneiss of igneous origin with sediments is shown
by Lawson in his study of the Lake of the Woods. Hégbom? has
described similar relationships which are shown by the rocks about
Upsala, Sweden.
The gneiss of the pre-Cambrian of the Adirondacks is so mingled
with limestone and other sediments that for years it has been a
mooted question whether to consider it of igneous or sedimentary
origin. It forms lenses and sheets in the sediments, or traverses
them so irregularly that an exact interpretation is difficult.
1 Can. Geol. Surv., Memoir No. 6 (1910), 73-78.
2 Bull. Geol. Instu., Univ. Upsala, X (1910-11), 39.
786 W. G. FOYE
However, C. H. Smyth, Jr.7 and H. P. Cushing? now consider
them igneous.
The gneisses of the Highlands of New Jersey may be described
in similar language. These are considered by W. S. Bayley? and
C. N. Fenner‘ to be sediments invaded by granite.
G. M. Dawson writes as follows concerning the Shuswap Ter-
rane of British Columbia:
The Shuswap rocks proper evidently represent highly metamorphosed
sediments with perhaps the addition of contemporaneous bedded volcanic
materials: . .... These bedded materials are, however, associated with a much
greater volume of mica-schists and gneisses of more massive appearance, most
of which are evidently foliated plutonic rocks, and are often found to pass into
unfoliate granites. The association of these different classes of rocks is so
close that it may never be possible to separate them on the map over any
considerable area... ..
A distinct tendency to parallelism of the strata or foliation with adjacent
borders of the Cambrian system has been noted in a number of cases. This
might imply that the foliation was largely produced at a time later than the
Cambrian, but materials of some of the Cambrian rocks show that the Shuswap
series must have fully assumed their crystalline character before the Cambrian
period. Jt seems, therefore, probable that the foliation of the Shuswap rocks may
have been produced rather beneath the mere weight of superincumbent strata than
by pressure of a tangentical character accompanied by folding
R. A. Daly, in a recent report on this same series, states that
it has been .injected by innumerable sills and laccoliths. He
concludes:
The extraordinary prevalence of sills and other concordant injections is
explained by the extreme fissility of the Shuswap sediments and greenstones.
This feature is due to static metamorphism.$®
Two hypotheses are offered, therefore, to explain the parallel
banding of pre-Cambrian rocks. In the Haliburton-Bancroft
area, Adams conceives that, in the process of intrusion by magmatic
tN.Y. State Mus., 41st Ann. Rept., II (18099), 469-97.
2 Bull. No. 115, N.Y. State Mus. (1907), 451-531.
3U.S.G.S., Raritan Folio, No. 191.
4 Journal of Geology, XXII (1914), 594 fi.
5 Bull. Geol. Soc. Am., XII (1901), 63-64.
6 Ann. Rept. Dept. Mines, Can. Geol. Surv. (1911), 3-12.
“BATHOLITHS” OF HALIBURTON-BANCROFT AREA 787
stoping, blocks of limestone were torn from the roof of the invading
granite batholiths and elongated parallel to the contact of the
granite and limestone by movements of the granite as it con-
solidated.
_ Daly believes that static metamorphism produced planes of
weakness within the Shuswap series and that sills of granite were
intruded along these planes.
Fenner,’ discussing the method of intrusion of the granites of
the New Jersey Highlands, states that in his opinion gaseous
emanations from the granite magma penetrated the sedimentary
rocks along planes of weakness and prepared the way for the
intrusion of granitic fluids. The intrusion of these fluids produced
banded gneisses.
It is, of course, entirely possible that intrusion in the Haliburton-
Bancroft region took place by magmatic stoping and that this
region is not analogous to the others described. The rock types
vary within the several areas and there is, necessarily, a corre-
sponding change in the structural relations. The limestones of the
Grenville series would undoubtedly be more altered by the meta-
morphic effects of the granite than the quartzose rocks of the New
Jersey Highlands and the Shuswap series.
It seems to the writer, however, that the facts shown by the
study of the Glamorgan gneissic area favor the theory of intrusion
by parallel penetration along planes of weakness rather than the
theory of intrusion by magmatic stoping.
If intrusion took place by magmatic stoping, the following
conditions must be postulated. The objections to each of these
conditions are noted.
1. The blocks from the roof of the 1. Intrusion by magmatic stoping
batholith were stoped off and elongated usually produces an irregular molar
parallel to the contact. contact. The igneous rock cuts the
sediments. Though the blocks were
elongated parallel to the contact, this
would not, except by chance, be parallel
to the stratification of the sediments,
and yet this is the relationship of the
banded structure of the rocks of the
Haliburton-Bancroft area.
* Journal of Geology, XXII (1914), 594 ff.
788
2. Adams postulates that the elonga-
tion of the blocks occurred in the later
stages of batholithic intrusion as the
granite solidified.
3. The limestone blocks, stoped from
the roof of the granite batholith, floated
and so were elongated by the movements
of the granite parallel to its contact.
W. G. FOYE
2. It would seem necessary that this
should be true; for a hot, fluid magma, if
too hot would melt the blocks and incor-
porate them into a homogeneous magma.
If it were too cold it could not elongate
them. The necessary conditions for the
production of parallel elongation, there-
fore, is a narrow temperature range
within which the blocks remain viscous.
This would be found, it would seem, at a
more or less constant distance from the
molar contact of the intruding batholith
with the country rock. As the magma
progresses upward, the central heat of
the batholith must likewise progress
upward and hence the parallel banding
of the batholith produced at any stage
would be destroyed in a later stage by
the complete solution of the blocks into
a homogeneous magma. The so-called
“batholiths” are in all stages of dis-
section yet the parallel structure is
persistent from center to edge. The
structure is not, therefore, a border
phenomenon as Adams’ theory would
demand.
3. Daly? has shown that limestone
blocks at high temperatures are much
heavier than fluid granite. Hence these
blocks should sink and leave a clear con-
tact which would be_ progressively
attacked by the hot granite magma.
This would not give rise to the parallel
structure observed. If, however, they
floated they would impede the attack of
the granite magma at the contact and
their solution or partial solution and
elongation would cause an enormous loss
of heat and render the further upward
progress of the batholith very difficult.
It is estimated by Adams and Barlow that 20 per cent of the
“‘batholithic’”’ areas consist of gray gneiss and amphibolite.
estimate is low for the districts visited by the writer.
This
Not only
these rocks but also bands of pure limestone are often found near
tI gneous Rocks and Their Origin (1914), 202.
“BATHOLITHS” OF HALIBURTON-BANCROFT AREA 789
the center of the gneissic areas, where, it would seem, by Adams’
_ theory, that the pure gneiss of the intruding batholith should be
found.
This fact makes it easy to believe that the granite was intruded
along planes of slight resistance, and that the limestone terrane
of the Grenville series became an immense steam pack, at the time
of the intrusion of the granite, with layers of gases followed by
fluid granite alternating with layers of limestone. The pre-
Cambrian granites were probably accompanied by an immense
amount of pneumatolytic gases. The loss of these gases at higher
levels due to decreasing pressures accounts for the gradual lessening
of the interaction of granite and limestone away from the main
granite mass, while within the gneissic areas the retention of the
gases allowed the granite to effect a complete change of the lime-
stone to gray gneiss and amphibolite. At certain places the granite
failed to penetrate great lenses of the limestone. The gases from
layers of fluid magma at the top and bottom of these lenses meta-
morphosed their borders but failed to affect their centers. Lenses
of pure limestone were, therefore, preserved in the midst of gray
gneiss and amphibolite.
It has been inferred that the intrusion of the granite occurred
along planes of weakness. These, as the structure now shows,
were parallel to the stratification of the limestones. Daly and
Dawson have stated that in the Shuswap area these planes were
_ due to static metamorphism. Fissility produced in this way would
be less apparent in limestones than in the quartzose rocks of British
Columbia. However, the fact that the gneissic structure of the
Laurentian gneiss is parallel to the stratification of the Grenville
series would favor the view that the granite solidified under condi-
tions of stress similar to those which produced the parting planes
along which it was intruded. A vertical dike near Baptiste Lake,
west of Bancroft, Ontario, shows horizontal schistose structure
similar to certain dikes described by Daly* in the Shuswap area.
Adams and Barlow? ascribed the gneissic structure of the Laurentian
gneisses to the pressure of intrusion of the granite magma. This,
t Cf. to figure in Guide Book No. 8, Part II, Internat. Geol. Cong., Can (1913), 130.
2 Can. Geol. Surv., Memoir No. 6 (1910), 78-81.
790 W. G. FOYE
however, would not explain a phenomenon such as that shown by
the dike just described (Fig. 2). It is believed that the fissility
which allowed the granite to intrude the sediments and the gneissic
structure of these granites were both results of a persistent force,
the static pressure of the overlying sediments. The Grenville
series is said by Adams and Barlow to be approximately 50,000
feet thick. This series compares with the Shuswap Terrane which
is 30,000 feet thick.
The elongation or compression of the amphibolitic layers and
the presence of amphibolitic inclusions may be explained as easily
by the theory of Daly and
Fenner as by that of Adams.
The granitic gases and fluids
must have had their origin at
certain definite points. At these
points they were pushed upward
and sideways along planes of
easy parting and a pine-tree
structure was produced. In
general, the increase of material
due to the addition of granite
Fic. 2.—A vertical dike showing hori- would produce a doming at the
zontal schistose structure. center of intrusion with qua-
quaversal dips away from these
points. However, the subsidence of the magma on cooling might
very possibly cause a collapse of the dome and irregular dips
would result.
The mechanism of lit-par-lit intrusion, as explained by Fenner,”
is dependent on the fluxing power of the pneumatolytic gases given
off by the granite. These go before and prepare the way for the
later intrusion of the granite magma. The prevalence of lit-par-
lit rather than batholithic intrusions in pre-Cambrian terranes
may be due, therefore, to the greater abundance of magmatic gases
in the earlier periods of the earth’s history. The vast amounts of
pegmatitic granite associated with pre-Cambrian areas lends
support to this theory.
t Journal of Geology, XXII (1914), pp. 594 fi.
eee
“BATHOLITHS” OF HALIBURTON-BANCROFT AREA 791
The facts presented above do not mean that cross-cutting bodies
are lacking in the Haliburton-Bancroft areas. They are found
but are by no means as common as concordant injections.
It seems fair to conclude, therefore: (1) that the so-called
“batholiths”’ were formed by the concordant injection of granite
into a fissile limestone terrane; (2) that this fissility was produced
by the pressure of the overlying sediments; (3) that the layers of
Fic. 3. ‘‘Stromatolithic” structure (C. N. Fenner, Jour. Geol., XXII [1914],
596).
limestones, lying between layers of molten granite, were permeated
by the pneumatolytic gases and fluids given off by the granite
and transformed to amphibolites or gray gneisses; (4) that the
concordant injection of the granite produced the dome-like char-
acter of the “gneissic’”’ areas; (5) that the term ‘‘batholithic” does
not describe the true character of these areas and the term “stro-
matolithic’’! is suggested in its place (Fig. 3).
t From Greek orpwua, “a layer,” and Avos, ‘a stone.”’ The noun “Stromatolith”
may be defined as a rock mass consisting of many alternating layers of igneous and
sedimentary rocks in sill relationship.
A CONTRIBUTION TO THE OOLITE PROBLEM
FRANCIS M. VAN TUYL
University of Illinois
INTRODUCTION
At the present time there are two prevalent theories of odlite
formation, namely, the inorganic, or chemical precipitation theory,
and the organic theory. Prior to the year 1890 the inorganic theory
was generally agreed to and it is to this day the most widely accepted
of the two.
In the year mentioned, however, Wethered' pointed out a close
relationship between the concretionary structure of the calcareous
algae Girvanella and that of true odlite, and showed that certain
so-called odlites of the Carboniferous and Jurassic of England really
consist, in part at least, of rounded calcareous masses secreted by
this organism, since they possess in addition to the concretionary
structure the vermiform tubules which characterize the genus. But
in this and again in a succeeding paper, entitled ‘‘The Formation
of Odlite,” which appeared in 1895,? Wethered was unable to demon-
strate the presence of the Girvanella tubules in typical odlite spher-
ules showing both radial and concentric structure, although he was
led to believe that these were also of algal origin.
Following closely upon Wethered as a champion of the organic
theory came Rothpletz, who published a paper on the origin of
odlite in 1892.3 This investigator upon studying the recent odlites
of Great Salt Lake found that where these were still in the water
they were usually covered by a bluish-green algal mass consisting
of the cells of Gloeocapsa and Gloeothece, forms which are known to
secrete carbonate of lime; and, when the odlite grains and rodlike
t Quar. Jour. Geol. Soc. London, XLVI, 270-83.
2 Ibid., LI, 196-209.
3 Botanisches Centralblatt, No. 35, pp. 265-68 (English translation by F. W. Cragin,
American Geologist, X, 279-82).
792
A CONTRIBUTION TO THE OOLITE PROBLEM 793
calcareous bodies on the shore were dissolved in acid, they all yielded
dead and shriveled fission algae. Rothpletz, therefore, concluded
that the odlites of Great Salt Lake are the product of lime-secreting
fission algae, and that their formation is proceeding day by day.
Furthermore, a study of the recent and near-recent odlites of
the Red Sea showed these also to contain minute grains of organic
material suggesting fission algae. But these differ from the Great
Salt Lake odlites in that their nuclei always consist of sand grains
and in that their concentric structure is less well developed. They
also. possess small vermiform canals filled with calcite, which are
interpreted as imprisoned algae of another type.
Rothpletz also remarks that certain elongated corpuscles pos-
sessing odlitic structures, which he interprets as organic, occurs in the
Lias limestone of the Vilser Alps, and concludes as follows: “‘Accord-
ing to the present stage of my researches, I am inclined to believe
that at least the majority of the marine calcareous odlites with
regular zonal and radial structure are of plant origin; the product of
microscopically small algae of very low rank, capable of secreting
lime.”
In spite of these discoveries by Wethered and Rothpletz, later
students of the odlite problem have tended to drift back to the
inorganic theory and to regard the association of odlites with algae
as accidental. Thus Linck’ has shown by experiment that odlites
similar to natural ones may be produced artificially by the action
of sodium carbonate and ammonium carbonate on the calcium sul-
phate of sea-water. He points out that these carbonates are formed
by decomposition of animal and plant tissues in the sea, and favors
the view that odlites have been formed in this way. That natural
odlites can be formed chemically is demonstrated by Vaughan,’
who points out that odlitic structure is now being developed in the
calcareous muds precipitated through the agency of bacteria off the
coasts of Florida and the Bahamas.
In a recent review of the whole question of odélite formation,
T. C. Brown? has endeavored to substantiate Linck’s conclusions
t Neues Jahrb., Beil. Bd. 16 (1903), pp. 495-513-
2 Jour. Washington Acad. Sci., II (1913), 302-4.
3 Bull. Geol. Soc. America, XXV (1914), 745-80.
704 FRANCIS M. VAN TUYL
and to discount the importance of the algal theory. To quote from
him: ‘The dead algal cells in the Salt Lake odlite are regarded as
cells which had selected the odlite as a point of attachment. They
became imprisoned within it by the further accretion of aragonite
by chemical precipitation.” He suggests that the decay of the
attached algae furnishes Na,zCO; which acts as a precipitating agent
and thereby aids the growth of the odlite.
As regards the importance of algae in the production of the
odlites of Great Salt Lake, future studies may be expected to throw
additional light on the problem. Microscopic examination of
these by several investigators has failed to reveal any indications
of algal structure in the calcareous grains themselves. On the other
hand, they exhibit highly developed radial and concentric structure.
THE PRAIRIE DU CHIEN OOLITE
Some time ago the writer had occasion to examine microscopi-
cally a siliceous odlite which marks the base of the Ordovician in
northeastern Iowa, and found to his surprise that the odlite grains
of this showed undoubted algal structures. The bed in question
constitutes the so-called transition member between the Prairie
du Chien dolomite and the Saint Croix sandstone. With reference
to this bed Leonard, in his “Geology of Clayton County,” says:
The lower Magnesian is not marked off sharply from the underlying Saint
Croix, but there is a transition from the one to the other through from fifteen
to twenty feet of calcareous sandstone or siliceous odlite. The rock is com-
posed of clear rounded grains of quartz cemented by lime carbonate. In
some beds this cementing material is quite abundant, in others there is only
enough to hold together the grains. The ledges vary in thickness from a
few inches to two or three feet. This siliceous odlite is well exposed in an old
quarry in the river bluff one and one half miles above North McGregor. The
transition beds are also seen in the section at Point Ann, just below McGregor.
Here there are alternating layers of sandstone and limestone and some odlite
similar to that described above.!
A bed of similar character and thickness has been described by
Calvin? as occurring at the same horizon in Allamakee County,
which lies directly north of Clayton. The writer has examined
t Iowa Geol. Survey, XVI (1905), 239-40.
2 Ibid., IV (1894), 61.
—oo
A CONTRIBUTION TO THE OOLITE PROBLEM 795
the member at the Point Ann exposure only, and the samples here
described and figured are entirely from that locality.
Microscopic examination of the rock shows it to consist of
imperfectly preserved siliceous oélite grains in a dolomitic matrix.
The history of the rock is briefly as follows: Subsequent to the
formation of the oélite, dolomitization set in, transforming the cal-
careous matrix completely, and many of the calcareous odlite grains
either wholly or in part, to dolomite. Alteration then ceased and
silicification of the unchanged, or only partly changed, odlite grains
ensued. The irregular areas of dolomite within the interiors and
the frayed-out borders of many of the silicified odlite grains are in
this way accounted for. The structure of grains which were com-
pletely dolomitized prior to silicification is almost entirely obliter-
ated, and these are often only with difficulty distinguished from the
matrix.
The odlite grains range from 0.1 mm. to 1.13 mm. in diameter,
and when well preserved show, in addition to the concentric and
radial structure, minute sinuous, enwrapping fibers very similar to
the tubules which characterize the Girvanella type of calcareous
algae. A comparison of the microphotographs of the odlite grains
with that of Girvanella problematica Nicholson, described and figured
by Rothpletz, in his memoir entitled ‘“‘ Ueber Algen und Hydrozoen
im Silur von Gotland und Oesel,’™ will bring out this striking
similarity (Figs. 1-6).
It should be recognized that the interwoven fibers of the odlite
have been partly obliterated by silicification. Doubtless these con-
sisted of hollow tubules filled with calcite, like those shown by Girva-
nella problematica prior to silicification.
The fibers of the organism of the odlite have an average diameter
of 0.015 mm. which agrees very closely with the diameter of the
tubules of Girvanella problematica, which varies from o.o1 to
0.018 mm., according to Rothpletz.
Typically the well-preserved odlite grains consist of an inner
structureless nucleus, followed by a narrow intermediate band
showing radial structure, and this again by an outer band bearing
1Kungl. Svenska Velenskapsakademiens Handlingar, Band 43, No. 5 (1908),
TAL I bikes, 1
Fic. 1.—Microphotograph of Girvanella problematica Nicholson. About X42.
After Rothpletz.
Fic. 2.—Microphotograph of peripheral section of a silicified odlite grain from
basal Ordovician at McGregor, Iowa. About X45.
Fic. 3.—Cross-section of another grain from the same locality. About X45.
Note the well-developed algal structure in the outer portion and the band showing
radial structure within this. The interior is not preserved.
Fic. 4.—Imperfectly preserved odlite grain. About X45. The interior and
peripheral portions of the grain were replaced with dolomite, with obliteration of struc-
ture, prior to silicification.
Fic. 5.—Silicified grain showing well-developed radial structure but with algal
fibers nearly obliterated. About X45.
Fic. 6.—Another grain showing fine concentric structure but with no distinct algal
fibers preserved. About X45.
A CONTRIBUTION TO THE OOLITE PROBLEM 707
sinuous fibers. In some instances, however, the two outer bands
grade gradually into each other without any distinct line of demarka-
tion; or indeed the radial structure may be entirely wanting and the
concentric structure may continue into the nucleus. The fibers are
best shown in peripheral sections of the grains. .In these they
appear to enwrap the bodies.
Some of the grains, however, show little or no trace of algal
fibers, but there is convincing evidence that this fact has resulted in
most, if not all cases, from the obliteration of original structures as
an accompaniment of silicification. All stages of such obliteration
may be traced under the microscope.
SOME EFFECTS OF CAPILLARITY ON OIL
ACCUMULATION’
A. W. McCOY
The University of Oklahoma
All rocks in the upper crust of the earth contain pore space.
The percentage by volume of this space varies from a fraction
of 1 per cent in the case of most fresh crystalline rocks? up to 4o
per cent in some sandstones. Below ground-water level these
openings are more or less saturated with water, which moves
about from points of higher to points of lower pressure.
The movement of water thus entombed does not exactly follow
hydrostatic laws, as can be observed by the small loss of head in
artesian flow. For example, an instance is cited} by Van Hise4
where water traveled under ground 150 kilometers with a loss of
only 50m. in head. This shows that the movement was very slow
(perhaps a few feet per year), for the friction through the porous
stratum was almost nothing. In the case of water moving in
large openings, such as pipes, friction is an important factor. A
somewhat similar example was observed by the author in Missouri,
where the loss of head by flow in the Roubidoux sandstone was
about 200 ft. in 75 miles. A theoretical means of comparison with
the observed facts is to note the size of the openings in the rocks.
All tubular openings less than 0.508 mm. are capillary. There-
fore, by geometrical proof, it can be shown that sandstones with
uniform rounded grains of less than 2mm. in diameter, would
contain mainly capillary openings. Rocks with uniform rounded
grains, regardless of the size of grain, contain about the same
t A paper read before the Geologic Conference of Oklahoma, January 7, 1916,
at Norman, Oklahoma.
2 Van Hise, Monograph, U.S.G.S. 47, p. 125.
3G. P. Merril, Rocks, Rock-Weathering and Soils, p. 198.
4 Monograph, U.S.G.S. 47, p. 587.
5 Alfred Daniell, Text Book of Physics, p. 315.
798
EFFECTS OF CAPILLARITY ON OIL ACCUMULATION 799
amount of pore space, and this is greater than in rocks which have
varying-sized and angular grains. Most rocks are made up of
particles irregular in shape and less than 2 mm. in diameter, con-
sequently the movement of underground water must be greatly
affected by capillary action, and evidently the forces of static capil-
larity must be overbalanced before movement can take place. For
that reason a discussion of Poiseuille’s law of flow in capillary
tubes has been omitted, and the conditions of static capillarity
are thought to be of first importance.
The phenomenon of capillarity—that of a column of liquid
rising or being depressed by a small opening—is due to two causes:
(z) the surface tension of the liquid, and (2) the fact that the mate-
rial of which the tube is composed has a greater or less adhesion
for the liquid than the cohesion of the liquid itself.
Surface tension is the force at the surface of a liquid, which
tends to make the liquid contract, and can be expressed by the
following formula:
a) jp eS ;
277 COS @
where r equals the radius of the tube; 4, the height of liquid
standing in the tube; gq, the density of the liquid; g, the accelera-
tion of gravity; and a, the angle of contact between the liquid
and the tube.
Surface tension is a linear function of the absolute temperature,*
and that for water can be expressed by:
b) T =o. 21(370—1) ?
where ¢ equals the temperature Centigrade.
Pressure causes some change in surface tension, but presumably
small. ‘For changes in the properties of water induced by pres-
sure of, say, 1,000 atmospheres are usually similar in magnitude
and direction to those observed when a relatively small quantity
of a salt is dissolved in it; and the surface tension of such dilute
(0.5 N or less) solutions differs by only a small percentage from
that of pure water.’
* Knipp, Physical Review, XI, 151.
2 Johnston and Adams, Journal of Geology, XXII, 9. 3 [bid.
800 A. W. Mccoy
Different substances have different surface tensions, which can
be calculated by means of formula a) with the necessary observed
factors. For instance, crude oil at 20° C. has an average surface
tension of about 25 dynes per cm.;? water at 18° C. about 75 dynes;
and mercury at 20° C. about 540 dynes.?
Surface tension also varies with the nature of materials in
surfacial contact. For instance, the surface tension of mercury
when in contact with water is different from when in contact with air.
Unfortunately, a number of such different values are not recorded,
so that this discussion is limited to liquids in contact with air.
It is necessary that the adhesion of the material in the tube be
either greater or less than the cohesion of the liquid, otherwise
there would be no chance for surface tension to display itself.
When adhesion is less than cohesion, depression in the liquid
results, as in the case of mercury and glass; when adhesion is
greater than cohesion, there is a rise in the capillary tube. If
adhesion greatly overbalances surface tension, the liquid surface
may break and the liquid mount up the sides of the vessel, as in
the case of some light oils in a low porcelain cup. Consequently,
before one liquid will replace another in capillary openings the
replacing liquid must not only have a greater surface tension but
also a greater adhesive power for the material of which the tube is
composed.
Capillary force according to equation a) is a function of surface
tension, contact angle, diameter of pore space, density of liquid and
acceleration of gravity. In the case of water-air surface the con-
tact angle is o, therefore (cos a) equals 1; the density of water is
1; so the equation resolves itself into:
h=kT/r,
where k equals 0.00204.
Starting with a temperature of 15° C., at a depth of 100 m., the
capillary pressures shown on p. 801 are computed from the above
formula. Pressures are recorded in kilograms per square centimeter.
The following calculations show, first, that capillary pressures
decrease with depth on account of the increase in temperature;
* Washburn, A.I.M.E., L, 831. 2 Tait, Properties of Matter, p. 264.
EFFECTS OF CAPILLARITY ON OIL ACCUMULATION 8ot
secondly, that above 750 m. capillary pressure in openings of 0.01
micron is greater than the combined rock and hydrostatic pres-
sures; therefore capillarity is most important in the upper 3,000 ft.
of the earth’s crust; and thirdly, that above 5,000 ft. one liquid of
greater surface tension and adhesion for the tube material should
readily replace a weaker liquid in small openings; or in other words,
the liquid of less surface tension should be concentrated in the
larger openings.
CAPILLARY PRESSURES UNDER VARYING CONDITIONS*
CAPILLARY PRESSURE FOR
Ewe Hyprostatic Pore DIAMETER OF Rocz HOSE ATG
AND CAPILLARY
METERSt PRESSURE ie es RESSURE aneconis
tooMc o0.o1rMc
TOON ereveace Io 03 306 27 316
BOO ry cision te 50 03 204 135 344
TIOOO seta sia sa) 100 027 278 270 378
ROO mbes reieiat: 200 025 250 540 450
* Johnston and Adams, op. cit., XXII, 13.
t An increase of temperature of 1° for every 30 m. was used to obtain these results.
Capillary phenomena can take place in openings of o.o1 micron,
as shown by Bakker,’ where he concludes that the minimum size
of capillary openings is a few times the diameter of the molecule.
According to Whitney,? mud contains more than 10,000,000,000
particles per gram. If these were perfectly round particles, so
that the pore space could be a maximum, the diameter of the
‘individual would be about 3 microns. Therefore the maximum
openings would be about 0.5 micron. Clay used in the following
experiments was made up of particles which varied from 1 to 5
microns in diameter, as measured by a microscope. The openings
then at a maximum would be a fraction of a micron. Now, since
the openings in mud are evidently less than 1 micron by both of the
above methods of approach, it has been assumed for the following
hypothetical problem, that in compressed shales where the particles
are not round nor of equal size the openings are diminished to
©.OI micron.
1 Zeitschrift fiir physikalische Chemie, LXXX, No. 2, 129.
2U.S. Dept. Ag., Weather Bureau, Bull, 4, p. 73-
802 A. W. McCOY
Capillary pressure of 300 atmospheres means that water will
enter the pore spaces above static water level until the pressure
in the pore tubes, due to the weight of the column of liquid above
or otherwise, is equivalent to 300 atmospheres pressure; or that,
if the water is held back by a gas or liquid of less surface tension, it
will accumulate a pressure in the said gas or liquid proportional
to the difference in capillary pressures for that temperature and
size of opening. |
The following assumptions have been made for a hypothetical
problem: (1) there exists a cavity or series of connected open-
ings, larger than o.5 mm., under a strip of rock 10,000 ft. wide
and 1,000 ft. thick. The openings in the rock above are as
small as o.or micron, and filled with water; (2) the material
below the cavity is an oil shale in which the openings are
0.01 micron, and that water is in the lower part of this shale
under sufficient head to make it rise to the level of the bottom
of the cavity.
The water will drive the oil into the open cavity with a pressure
equal to the difference in the capillary pressures of oil and water
for that size of opening. This amount for the given temperature
of 15° C. and openings of 0.01 micron is approximately 200 atmos-
pheres, or about 400,000 lb. per sq. ft. The weight of the rock
column above is approximately 150,000 Ib. per sq. ft.; and that of
the full water column would be less than 62,000 lb., because the
column cannot possibly act upon a full square foot, but only upon
the area of pore space, for convenience say 50,000 lb. Now the
resultant pressure upon the rock above the cavity is 400,000 minus
(150,000 plus 50,000), or 200,000 lb. per sq. ft.
This pressure acts as upon a beam fixed at both ends. The
capillary water above prevents the rising of the oil into the rock,
but in turn affords no downward pressure on the oil in the opening,
other than the weight of the hydrostatic column, as has been
accounted for in the above assumptions.
The deflection for a beam fixed at both ends with a uniform
load may be expressed by the following formula:
wii
d=" 34E1 :
EFFECTS OF CAPILLARITY ON OIL ACCUMULATION 803
where d is the deflection; w, the uniform load; 1, length of beam;
£, the modulus of elasticity; and I, the moment of inertia.
Substituting the values for a beam of rock 10,000 ft. wide,
1,000 ft. deep, 1 ft. broad, with E equal to 6,000,000 lb. per sq. in.
(the value of granite), and I equal to 643/12 or (1,000)3/12, the
equation resolves itself into the following:
200,000 X 10,000 X 10,000 10,000 X 10,000 12
384. X 6,000,000 X 144 X 1,000 X 1,000 X 1,000
or approximately 72 ft. This means an anticline with a dip each
way from the crest of about 1 degree.
EXPERIMENT I
Statement.—An open glass cylinder (3 in. in diameter, and 8 in. in length)
was placed in a pan of wet sand, so that the sand filled the lower one-third
of the cylinder. The water had free access from the sand in the pan to the
sand in the cylinder. Then a layer of
oil-saturated mud was placed in the cyl-
inder upon the wet sand; this mud occu-
pied about one-third of the cylinder and
was above the level of the water in the
pan. The cylinder was then filled with
dry sand, and the top sealed with a tube
attachment toa closed barometer. Read-
ings of the mercury were taken before
sealing and compared with a standard
barometer in the same room.
Results.—The water migrated up-
ward about 1 cm. into the mud and the
oil moved about the same amount into the dry sand. The mercury had risen
within 24 hours, about 243 cm. over the atmospheric pressure as compared
with the barometer; it then remained stationary. The oil also migrated down
into the wet sand and collected in some of the larger openings.
Pry send
Oi shale
Wet sond
Wet Sond connected
with C
closed Saromerver :
Tube conzecting jar Experiment [
and bafomete;
DM 89H%
EXPERIMENT 2
Statement.—A (2-in.) layer of wet sand was placed between two layers
of oil in a (8 in.X4 in.X4 in.) rectangular glass box. The sand layer was ar-
ranged in an arched manner so that the artificial anticline dipped about 30
degrees to either side. The sand grains in the top of the curve were small (all
passing a 4o-mesh sieve), while those in the troughs were comparatively coarse
(none passing a 10o-mesh sieve). The top was sealed with paraffin and water
804 A..'G. Mccoy
was allowed to enter the box through openings at the lowest horizon of the
sand. This water level was never as high as the top of the curve in the sand.
Results —The water entered
the mud in both directions from
the sand layer and replaced about
an inch strip of the oil in the mud.
The oil moved into the coarser
grains of sand and within 24 hours
2 Ql shale there was an oil pool in both
Fine sand . . .
& Gebescdmiing worer Experiment 2 synclines on either side of a water-
& Parattin seal’ | . 5 .
F Lines showing replece- filled anticline. Later, the oil
ment of of/ wy shale
began to move out of the openings
which admitted water from the outside, and collected upon the surface of
the water.
EXPERIMENT 3
Statement.—A (3-in.) layer of oil mud was placed in a (round 14-in. diam-
eter) pan, which had a number of small holes in the bottom. A circular lens
of dry sand (3 in. in diameter and 3 in. thick) was fitted down in the center at
the top of the mud. The surface
was leveled as carefully as possible
and covered with a }-in. layer of
paraffin. This pan was then set
in a pan of wet sand, so that the
water level stood about 1 in.
below the top of the mud in the
first pan.
A tens of ary sond
Results—After two weeks the 3 ov shore” *””
C Wet sand He also dis-
cusses the nomenclature of ripple marks at much length in a paper
published in 1904,° and elsewhere quotes Lieutenant Damant, R.N.,
1H. T. De la Beche, The Geological Observer (Philadelphia, 1851), p. 506.
2H. C. Sorby, “On the Structures Produced by the Currents Present during
the Deposition of Stratified Rocks, ” Geologist, April, 1859, p. 141.
3A, R. Hunt, “On the Formation of Ripple-Mark,” Proc. Roy. Soc. London,
XXXIV (1882), 2, 18.
4A. R. Hunt, “The Descriptive Nomenclature of Ripple-Mark,” Geol. Mag.,
N.S., I (1904), 411.
5A. R. Hunt, “On the Action of Waves on Sea-Beaches and Sea-Bottoms,”
Proc. Roy. Dublin Soc., N.S., TV (1884), 261-62.
6A. R. Hunt, “The Descriptive Nomenclature of Ripple-Mark,”’ Geol. Mag.
N.S., I (1904), 410-18.
812 STUDIES FOR STUDENTS
as having observed ripple marks while diving at depths of 60 and
7O Teel.
In 1883, the year following the publication of Hunt’s earliest
paper cited above, there appeared three important essays on ripple
marks: one by De Candolle on “Rides formées 4 la surface du
sable déposé au fond de l’eau et autres phénoménes analogues’’;
another by Forel on ‘‘ Les rides de fond étudiées dans le lac Léman”’
and a third by Darwin “On the Formation of Ripple-Mark in
Sand.” De Candolle produced ripple marks artificially by experi-
menting, not only with sand and various substances in powdered
form covered by water, but also with liquids of varying viscosity,
covered with water and other liquids.?, Regarding sand or powder
mixed with water as a viscous substance, he concluded from his
experiments that ‘‘when viscous material in contact with a fluid
less viscous than itself is subjected to oscillatory or intermittent
friction, resulting either from a movement of the covering fluid or
from a movement of the viscous mass itself with respect to the
covering fluid, (1) the surface of the viscous substance is ridged
perpendicularly to the direction of friction, and (2) the interval
between the ridges is directly proportional to the amplitude of the
friction-producing movement.” That ripple marks depend on
simple friction alone, and not on any change of level in the covering
liquid, such as occurs during wave action, De Candolle proved by
an experiment with a rotating disk submerged in a tank of water.
After submerging the disk and mixing an insoluble powder in the
water, the apparatus was left until the powder settled on the disk
and floor of the tank as an even film, and the water came to rest.
An oscillatory rotary movement then applied to the disk caused
radiating ripples to form upon it, while no ripples formed on the
stationary bottom, and the surface of the water remained quiescent.
The author concludes that the formation of ripples in sand, whether
under currents of air or under water currents, is identical in origin
with the formation of water ripples under moving air. If the cur-
tA. R. Hunt, “Facts Observed by Lieut. Damant, R.N., at One Sea-Bottom,”’
Geol. Mag., N.S. WW. (1908), 31-33.
HO. Gle Candiaite: ‘Rides formées 4 la surface du sable déposé au fond de l’eau et
autres phénoménes foalosncs! Archives des sciences physiques et naturelles, 3° Sér.,
IX (1883), 241-78.
ae anil
STUDIES FOR STUDENTS 813
rent moves always in one direction we have intermittent friction
due to varying velocities. Otherwise we have oscillatory friction
due to alternating change of direction. Current ripples result
from the first type of friction, oscillation ripples from the second.
Forel in his excellent essay on “‘Les rides de fond étudiées dans
le lac Léman”” sets forth the mature results of studies which had
been briefly mentioned by him in three communications of earlier
date.» Abandoning his first theory, that the formation of ripple
marks is dependent in part upon the vertical pressure of water
waves upon the bottom,’ Forel reached the following important
conclusions as the result of many careful observations and experi-
ments: (1) Current ripples are asymmetrical and migrate with the
current like ordinary sand dunes, whereas oscillation ripples are
stationary and symmetrical. (2) Each oscillation ripple is really
a composite of two current ripples, resulting from the action of
two currents moving alternately in opposite directions, each cur-
rent attempting to form the ridge into a current ripple migrating
with it, but being defeated when the return current tries with
equal force to shape the ridge into a current ripple directed in the
opposite sense. (3) The length of the water body has no direct
effect on the spacing of the ripples. (4) Other things being equal,
the ripples are more closely spaced with increasing depth. (5) At
a given depth, and with other conditions uniform, the ripples are
more widely spaced with increase in coarseness of sand grains.
(6) Ripples once formed do not experience a change in spacing as
a result of diminishing amplitude of oscillation of the water,
although the original spacing does depend upon the amplitude of
oscillation, as pointed out by De Candolle. (7) For any given
coarseness of sand grains there is a certain mean velocity of the
oscillating currents which will produce ripples; lower velocities
1 F, A. Forel, ‘‘Les rides de fond étudiées dans le lac Léman,” Archives des sciences
physiques et naturelles, 3° Sér, X (1883), 39-72.
2F, A. Forel, “‘La formation des rides du Léman,” Bulletin de la Société Vaudoise
des sciences naturelles, X (1870), 518; ‘Les rides de fond,” ibid., XV (1878), P.V. 66-
68; “Les rides de fond dans le golfe de Morgues,” tbid., 76-77.
3F. A. Forel, “La formation des rides du Léman,” Bulletin de la Société Vaudois
des sciences naturelles, X (1870), 518; “Les rides de fond étudiées dans le lac Léman,”
‘Archives des sciences physiques et naturelles, 3° Sér., X (1883), 40.
814 STUDIES FOR STUDENTS
will fail to move the sand grains, and hence cannot build ripples,
while higher velocities agitate the whole mass of sand so violently
that no ripples can form. (8) The formation of ripples is initiated
by some obstacle or inequality on the surface of the sand, behind
which sand grains accumulate in the eddy caused by its presence;
this leaves a furrow on either side of the initial ridge, .due to the
abstraction of sand accumulated in the ridge; and these furrows
in their turn cause additional ridges to develop on their outer mar-
gins, and so on. (g) In a given locality, ripple marks almost
always form with the same spacing, regardless of the varying
intensity of winds and waves affecting the water body; this is in
consequence of laws 7 and 6 stated above. (10) The depth at
which ripple marks may form is limited by the depth to which
wave action may extend with sufficient energy to move the bottom
sands; hence it depends on the size of the waves, and therefore in
part indirectly on the size of the water body; in the Rhone, the
limiting depth is a few decimeters; in Lake Geneva, some ten
meters; and in the ocean, from 20 to 188 meters, according to
Lyell and Siau. Forel revised De Candolle’s law regarding the
relation of ripple spacing to the amplitude of the friction-producing
movement to read: “The breadth of the ripples, or the distance
from one crest to another, is the length of the path followed during
a single oscillation by a grain of sand freely transported by the
water.’’ The length of this path varies directly as the horizontal
amplitude of the oscillatory movement of the water, directly as
the velocity of that movement, inversely as the density of the sand,
and inversely as the size of the sand grains.
Darwin’s paper ‘‘On the Formation of Ripple-Mark in Sand”
is especially noteworthy for its careful analysis of the vortices
which are so important a factor in the construction of the ripples.
When symmetrical oscillation ripples were subjected to the action
of a steady current, Darwin noticed that not only did sand grains
migrate up the weather slope of ‘each ripple with the current, but
that they also ascended the lee slopes, apparently against the cur-
rent. This proved conclusively the existence of vortices. Darwin
*G. H. Darwin, “On the Formation of Ripple-Mark in Sand,” Proc. Roy. Soc.
London, XXXVI (1883), 18-43.
STUDIES FOR STUDENTS 815
then proceeded to study the vortices by watching the movements
of a drop of ink released from the end of a fine glass tube at that
point in the water where the action was to be observed. In this
manner the vortices associated with the alternating currents which
produce oscillation ripples were analyzed with a high degree of
precision, and much light was thrown upon the method of ripple
growth. Darwin concluded that “the formation of irregular
ripple marks or dunes [current ripples] by a current is due to the
vortex which exists on the lee side of any superficial inequality
of the bottom; the direct current carries the sand up the weather
slope and the vortex up the lee slope. Thus any existing inequali-
ties are increased, and the surface of sand becomes mottled over
with irregular dunes.” The intermittent friction which De
Candolle adduced is not essential in this explanation of current
ripples. Oscillation ripples of regular pattern are changed by
a continuous current into regularly spaced current ripples; but a
uniform current cannot of itself initiate regularly spaced ripple
marks. ‘‘Regular ripple mark [oscillation ripples] is formed by
water which oscillates relatively to the bottom. A pair of vortices,
or in some cases four vortices, are established in the water; each
set of vortices corresponds to a single ripple crest.” Forel’s con-
ception of an oscillation ripple as a composite of two current
ripples formed alternately by oscillating currents is regarded as
correct; but his law for the relation of ripple spacing to amplitude
of oscillation is believed to require some modification.
Further studies of ripple-forming vortices were made by
Mrs. Hertha Ayrton, the results of which were not published until
1910.t With the aid of well-soaked grains of ground black pepper,
or of particles of potassium permanganate dissolving and coloring
the water while the latter was in oscillation, she observed the
formation of vortices and endeavored to explain the mechanics
of their growth. Although she expressed disagreement with the
conclusions of Darwin and others on certain points, most of her
results afford essential confirmation of their main contentions.
Some doubt must attach to certain of her deductions, such as
1H. Ayrton, “The Origin and Growth of Ripple-mark,” Proc. Roy. Soc. London,
Ser. A., LX XXIV (1910), 285-310.
816 STUDIES FOR STUDENTS
one to the effect that no ripple-forming vortex occurs in the lee
of an obstacle over which a steady current is passing, and that
hence ‘‘a steady current is unable either to generate or to maintain
ripple mark.”’
The British Association Reports for the years 1889, 1890, and
1891 contain three papers by Reynolds on the action of waves and
currents in model estuaries, in which are some valuable observa-
tions regarding what may well be termed giant tidal ripples.
While experimenting with artificial tidal currents, Reynolds dis-
covered that current ripples were formed in the model estuaries.
By making due allowance for the difference in size between the
model estuaries and those in nature, he concluded that real tidal
currents ought to produce very large current ripples, possibly
7 or 8 feet in height and 80 to 100 feet apart.2, Some years later
Vaughan Cornish discovered natural tidal ripples of the same type
as those produced artificially by Reynolds, having a height of
2 feet and an average distance of more than 37 feet from crest to
crest. In two later papers Cornish described giant tidal ripples
more fully, and illustrated their essential features with a large series
of beautiful photographs.4 Some of these ripples have a height
of nearly 3 feet above the intervening troughs, and a distance
between crests of from 66 to 88 feet in extreme cases. The giant
ripples are often covered with ordinary ripple mark, and while
Cornish recognized that the larger forms were produced by the
continuous steady flow of tidal currents, he was at first inclined to
invoke pulsatory currents in order to explain thesmaller ripple mark.5
t Osborne Reynolds, “Report of the Committee Appointed to Investigate the
Action of Waves and Currents on the Beds and Foreshores of Estuaries by Means of
Working Models,” Rept. British Assoc. (1889), pp. 327-43; ibid. (1890), pp. 512-34;
ibid. (1891), pp. 386-404.
2 [bid. (1889), p. 343.
3 Vaughan Cornish, “On Tidal Sand Ripples above Low-Water Mark,” Rept.
British Assoc. (1900), Ppp. 733-34-
4 Vaughan Cornish, “‘Sand Waves in Tidal Currents,” Geogr. Jour., XVIII (1901),
170-202; ‘“‘On the Formation of Wave Surfaces in Sand,” Scottish Geogr. Mag., XVII
(1901), I-11.
5 Vaughan Cornish, “On Tidal Sand-Ripples above Low-water Mark,” Rept. British
Assoc. (1900), p. 733; ‘“‘Sand Waves in Tidal Currents,” Geogr. Jour., XVIII (1901),
197-98; ‘‘On the Formation of Wave Surfaces in Sand,” Scottish Geogr. Mag., XVII
(1901), 8.
it ed 2
STUDIES FOR STUDENTS 817
- This theory seems to be a survival of De Candolle’s erroneous
idea that “intermittent friction” is essential to the production
of current ripples, and is practically abandoned by Cornish in his
more recently published book on Waves of Sand and Snow. Gil-
more described tidal ripples on the Goodwin Sands having a height
of ‘‘two or. three feet.’
It should be noted that all of the giant ripples referred to above
belong to the asymmetrical type; they are true current ripples.
So far as I am aware no giant oscillation ripples have ever been
observed along modern shores. It may be doubted whether tidal
currents could form symmetrical ripples, notwithstanding Rey-
nold’s suggestion to the contrary. The flow and ebb of the tide
constitute an oscillating current, it is true; but the currents are
often of unequal force. Where equally strong, each current per-
sists long enough to remodel the ridges formed by the preceding
current, giving them an asymmetrical form appropriate to the
current operating last. On the other hand, Gilbert has described
structures in the Medina sandstone formation of New York which
he believed to be giant ripples of the symmetrical type, formed by
oscillating currents due to wave action. In dimensions these
ridges were similar to the average examples of tidal ripples described
by Cornish, having a height of from 6 inches to 3 feet, and a dis-
tance from crest to crest of from 10 to 30 feet; but their nearly
symmetrical form did not suggest a similar origin. Gilbert reached
the tentative conclusion that they were formed by waves 60 feet
high in deep water of a broad ocean. This conclusion was criti-
cized by Fairchild, who advanced convincing arguments in support
of the opinion that the forms in question were beach structures,
possibly successive beach ridges built on the strand.* Branner
? Vaughan Cornish, Waves of Sand and Snow (London, 1914), pp. 289-90.
2 John Gilmore, Storm Warriors, or Lifeboat Work on the Goodwin Sands (London,
1874), pp. 108-9.
3 Osborne Reynolds, “Report of the Committee Appointed to Investigate the
Action of Waves and Currents on the Beds and Foreshores of Estuaries by Means of
Working Models,” Rept. British Assoc. (1889), DP. 343-
4G. K. Gilbert, ‘“‘Ripple-Marks and Cross-Bedding,” Bull. Geol. Soc. Amer.,
X (1899), 135-40.
s H. L. Fairchild, “Beach Structure in the Medina Sandstone,’ Amer. Geologist,
XXVIII (1901), 9-14.
818 STUDIES FOR STUDENTS
suggested that they might represent fossil beach cusps seen in
cross-section.”
In 1911 A. P. Brown published a paper entitled ‘“‘The Formation
of Ripple-Marks, Tracks, and Trails,”’ in which he endeavored to
show that asymmetrical ripples (current ripples) are formed by
deposition, whereas symmetrical ripples (oscillation ripples)
result from the erosion of a formerly smooth botton, consequent
upon the rippling of overlying water by wind action.? His con-
clusions do not appear to be supported by a sufficient body of con-
vincing evidence, and are opposed by theoretical considerations
and by the great body of experimental data already referred to.
In presenting his theory this author makes no reference to the
many previous investigations of ripple marks of all kinds, the
important results of which have been summarized above.
Ripple marks have repeatedly been discussed in connection with
the interpretation of fossil ripples found in sedimentary rocks.
We need mention but a few of these discussions in the present con-
nection. As early as 1831 Scrope described fossil ripple marks
found on slabs of marble, and explained them as due to the oscil-
latory movements of shallow water. Darwin, starting from the
very questionable assumption that a great ebb and flow of the tide
is essential to the formation of numerous ripples, concluded that
the presence of a large number of ripple marks in a geological
formation indicates with a considerable degree of probability that
the tides of early times rose higher than those of today.4 Van Hise
figured and described one type of oscillation ripples, and empha-
sized their value as criteria for determining the original altitude
of steeply inclined strata.s
tJ. C. Branner, editorial note, Jour. Geol., [IX (1901), 535-36.
2A. P. Brown, “The Formation of Ripple-Marks, Tracks, and Trails,’ Proc.
Assoc. Nat. Sci. Philadelphia, LXIII (1911), 536-47.
3G. P. Scrope, ““On the Rippled Markings of Many of the Forest Marble Beds
North of Bath, and the Foot-Tracks of Certain Animals Occurring in Great Abuf-
dance on Their Surfaces,”’ Proc. Geol. Soc. London, I (1831), 317-18.
4G. H. Darwin, “On the Geological Importance of the Tides,’’ Nature, XXV
(1882), 214.
5C, R. Van Hise, ‘‘Principles of North American Pre-Cambrian Geology,’
Sixteenth Ann. Rept. U.S. G. S., Part I (1896), 719-21.
= ee eC
STUDIES FOR STUDENTS 819
Spurr showed that where continuous deposition takes place from
a current which constantly maintains asymmetrical ripples on the
surface over which it flows, the forward movement of the ripples
combines with the deposition of heavier and larger fragments in the
troughs and lighter particles on the crests to give a peculiar type of
false bedding in the resulting formation.t Jaggar criticized Spurr’s
conclusions on the ground that his own experiments and observa-
tions indicated that ripple marks could not be produced in hetero-
geneous material;? but Spurr met the criticism with a fuller
discussion of the matter in which his original contention is well sus-
tained. A short time previously Sorby had described a somewhat
similar phenomenon in a paper’ printed almost exactly half a
century after the publication of his first account of ripple marks,
already cited. From an examination of the “ripple-drift” type of
false bedding in rocks, Sorby believed that one could “ascertain
with approximate accuracy, not only the direction of the current
and its velocity in feet per second, but also the rate of deposition
in fractions of an inch per minute.”> Additional discussions of
fossil ripple marks are cited by Kindle in his paper referred to at
the beginning of this article, but need not be repeated here.
1 J. E. Spurr, ‘False Bedding in Stratified Drift Deposits,’ Amer. Geologist, XIII
(1894), 43-47.
2T. A. Jaggar, Jr., ‘Some Conditions of Ripple-Mark,” Amer. Geologist, XIII
(1894), 199-201.
3J. E. Spurr, ‘Oscillation and Single-Current Ripple Marks,” Amer. Geologist,
XIII (1894), 201-6.
4H. C. Sorby, “On the Application of Quantitative Methods to the Study of the
Structure and History of Rocks,” Quart. Jour. Geol. Soc. London, LXIV (1908), 180-85.
3 Ibid., pp. 181, 197-99.
REVIEWS
Geology of Saratoga Springs and Vicinity. By H. P. CusHinc and
R. RUEDEMANN. New York State Museum; Bull. No. 160,
ro14.» Pp. 177, pls..20, figs: 17, maps"2.
Scientific interest regarding Saratoga Springs and vicinity centers
about its mineral waters, and this report has been published in response
to a demand for detailed information on local geological conditions.
Rocks of Pre-Cambrian, Cambrian, and Ordovician age outcrop
in the area. The Paleozoic rocks are divided into deposits of eastern
and western troughs, characterized by different sets of formations. The
western trough was being eroded in Lower Cambrian times, but in the
east the Georgian is the only Cambrian present. The rocks of the
western division are horizontal or nearly so, but in the east the beds are
intensely folded and crumpled. Two great normal faults with a number
of branches cross the Saratoga quadrangle. These are known to be
genetically connected with many of the mineral springs.
A unique feature is the Northumberland volcanic plug. It outcrops
just north of Schuylerville as a knob of extrusive rock and is unlike any
other igneous rock in the state. It has been connected with one theory
for the origin of the mineral springs, but unfortunately the authors were
unable to determine with certainty whether the rock is in place or not,
and are in doubt in regard to calling it a volcanic neck or a fragment of
a surface flow.
It was planned to have Professor Kemp write a chapter for this
bulletin on the origin of the mineral waters but his results were published
in an earlier report. The authors are not convinced that Kemp’s con-
clusions are justified by the field evidence. Kemp holds that the mineral
waters, in part at least, are of magmatic origin. He cites as proofs their
local occurrence, the volcanic neck, the large amount of free CO., and
the almost complete absence of sulphates. The authors believe that
the absence of carbonated waters to the north is due to lack of shale
covering and resulting dilution with surface waters. They hold that
the volcanic knob furnishes no evidence of igneous activity of sufficient
recency to justify connecting it with present-day juvenile waters. The
abundant CO, may come from deeply buried impure limestones and
820
REVIEWS 821
shales. The absence of the SO, radicle does not dismiss the possibility
of connate waters as a source of the mineral salts. The sulphates
originally in the connate waters may have been lost as the waters moved
along toward the surface by some such chemical reaction as the precipita-
tion of gypsum by the action of sodium sulphate on calcium carbonate
in the presence of free CO,.
Thus the chief problem that this quadrangle offers is held in question
still, but this is not due to lack of skill or painstaking effort on the part
of the authors of this report. It is a worthy contribution to the geologi-
cal literature of this state. W.B.W.
Genesis of Pyrite Ores of St. Lawrence County. By C. H. Smrru, JR.
New York State Museum, Bull. No. 158, 1912, pp. 143-82.
Figs. 29.
Under the most favorable conditions, definite conclusions regarding
the geneses of ore bodies cannot always be drawn, and when these are
_ found in bodies of rock as highly metamorphosed as the Grenville series
many complications arise.
In this area, pyrite is widely disseminated, but the ore bodies are
associated only with “‘rusty gneisses thought to be metamorphosed
impure sandstones and shales.” The writer believes that the metallizing
period was subsequent largely to the main period of metamorphism, and
was brought about by magmatic emanations permeating the gneisses
and replacing with pyrite certain minerals which are usually very stable.
These emenations came from the abundant intrusions after active move-
ment of the magmas had ceased. It is not stated that the pyrite all
came from the magmas. In fact, to explain the association of the ore
bodies with the gneisses alone, it is suggested that only the sulphur
was of igneous origin, and that the iron was furnished by the meta-
morphosed sediments. To cover minor occurrences of pyrite three addi-
tional periods of formation are postulated, but are not considered to have
been of importance in determining the ore bodies.
Additional points of interest are found in the lack of association of
the ore bodies with gabbros, as some authors have stated in other areas,
and possible genetic relations of pyrite with associated graphite.
The explanation of the ore bodies strikes one as quite involved, but
the author assures us that it is in very small proportion to the complexity
of field problems and conditions.
W. B. W.
822 REVIEWS
Geological History of New York State. By WitttamM J. MILLER.
New York State Museum, Bull. No. 168, 1914. Pp. 130,
pls. 52, figs. 4o.
This bulletin is a brief summary of the geological history of the state.
It was the intention of the author to presuppose no scientific knowledge
of geology on the part of his readers, and that the work should be in
the nature of a textbook. A few pages in the introduction are devoted
to geologic processes and throughout the context an effort is made to
define technical terms. The reviewer does not believe the author
succeeded in making the report sufficiently non-technical to be popular
with laymen. It will serve better as a reference book for geologists
who wish a brief statement of some of the larger phases of the region’s
history.
The report is illustrated with many excellent photographs of uncon-
formities and other structural and physiographic features which abound
in the state.
Unfortunately this report, in common with other New York reports,
does not contain a table of contents and its value as a reference book is
impaired thereby.
W. B. W.
Origin of Hard Rock Phosphates of Florida. By E. H. SELLARDS.
Florida Geol. Survey, Fifth Annual Report, 1913, pp. 23-80,
pls. 9, map I.
The hard rock phosphates are found chiefly as bowlders and irregular
fragments in a formation of Pliocene age that the author has named
Dunnellson. The formation is rather heterogeneous but a phase of
light-gray sands is the usual matrix in which the phosphate rocks are
imbedded.
Theories generally advanced to explain these deposits have involved
some form of guano alteration. The author believes the real source of
the phosphate was from phosphoric acid derived from the disintegration,
in situ, of overlying beds. The acid was borne downward by ground-
water, and replaced limestone, or was chemically precipitated. No
reactions are suggested for the latter process. The deposits are asso-
ciated with clay lenses and other conditions that interfere with the free
circulations of ground-waters. It is suggested that the presence of
precipitating agents may be the important factor here rather than the
retardation of ground-water circulation. The shattered and hetero-
—
REVIEWS 823
geneous character of the formation is explained by the caving in of solu-
tion cavities and their subsequent refilling.
The theory presented seems to explain the larger features of the
phosphate deposits, but the report should be considered a statement of
progress of investigation, rather than the last word in explanation of
the deposit.
W. B. W.
Water Supply of Eastern and Southern Florida. By E.H.SELLARDS.
Florida Geol. Survey, Fifth Annual Report, 1913, pp. 113-
288, pls. 5, figs. 17, map 1.
This report covers in detail an area of twenty-two counties in which,
for the most part, the artesian waters may be tapped by flowing wells.
This area includes the outer rim of counties along the eastern, southern,
and southwestern borders of the state.
The principal aquifer is the Vicksburg limestone of Oligocene age.
Underlying the whole state, this formation is exposed in the central part
and dips beneath younger formations to the east and south. These
younger beds have not been well differentiated and some wells may
obtain water from them, but strong flows are from the Vicksburg.
The structure includes a low anticline with its axis dipping gently to
the east in the central part of the state. The water-bearing horizon is
100 feet below the surface along the coast, and near the crest of the anti-
cline. In the northeast corner of the state the wells are from 300-400
feet deep and at the southern extremity from goo-1,000.
The gentle dip of the strata does not furnish strong pressure in any
locality and a head of 25 feet is rather exceptional. Local topography
affects the distribution of the flowing wells.
In some areas there has been great development of the artesian water
supply. There are not less than 500 flowing wells in the city of Jackson-
ville. Statistics covering recent years show a progressive loss of flow
from the wells in this city.
Much of the artesian water of the state is not potable on account of
mineral salts, chiefly sodium chloride. This is notably true in the
southern part. All the underground water of the state is very generally
charged with hydrogen sulphide, but its use for domestic purposes is
not prevented thereby.
A small area of flowing wells in the western part of the state is not
treated in detail in this report. :
W. B. W.
824 REVIEWS
Geology of North Creek Quadrangle. By Wrtt1am J. MILLER.
New York State Museum, Bull. No. 170, 1914. Pp. go, pls.
14, figs. 9, map 1.
This quadrangle lies wholly in Warren County, New York, in the
southeastern Adirondacks. It is of geologic interest chiefly because of
certain rock types and structures. At the present time no rocks of
later age than Pre-Cambrian are present, but Paleozoic outliers just
off the map seem to prove that late Cambrian and probably early Ordovi-
cian sediments have been removed. The Grenville series makes up the
meta-sedimentary rocks, and the author believes the evidence favors
their Archeozoic rather than Proterozoic age. This series has a lime-
stone member of remarkable thickness, 10,000-12,000 feet, and below
this is 3,000 feet of quite pure quartzite.
About 60 gabbro outcrops are shown on the map, usually with
elliptical ground-plans. Their form is that of small stocks or bosses,
rather than dikes. The author believes these gabbro occurrences
furnish strong evidence in favor of Daly’s magmatic stopping and
assimilation hypothesis. The igneous masses were not intruded by
pushing aside the country rock, but rather by a process of replacement.
Marked primary variations in the gabbros and the presence of inclusions
as xenoliths are cited in support of this theory and seem to make a
strong case.
Garnets are present in the area in quantities of some economic
importance. Some of the occurrences are attributed to the assimilation
of Grenville sediments, and subsequent crystallization from “original
magmas.” This use of the term “original magma” for a magma that
has assimilated considerable quantities of sediments is questionable.
W. B. W.
The Waterlian Formations of East Central Kentucky. By W. C.
Morse and A. F. Forerste. Kentucky Geol. Survey, Bull.
No. 16; ° Pp) 76; figs.-s. |
Stratigraphic relations of the Mississippian beds in Kentucky are
of interest for economic reasons. In Ohio and West Virginia forma-
tions in the Waverly series are oil- and gas-producers and their extension
into Kentucky is a fact of considerable importance.
This report covers twelve counties in the east-central part of the
state. The beds were traced southward from known sections in Ohio,
REVIEWS 825
making the correlations fairly certain. The sections show that toward
the south the sandstones of the oil horizons of Ohio rapidly grade into
shales. Even the shales of the Bedford and Berea formations become
very thin although they do not disappear. These changes are unfavor-
able for oil-bearing sands in the southern part of the state.
A number of changes in correlations in formations of the Waverlian
are made from those given in earlier Kentucky reports and in the
Richmond Folio. The latter part of the bulletin treats of the possi-
bilities of these beds in producing building stones and clays. If a map
of the area covered by the report had been given it would have made
part of the discussion more intelligible.
W. B. W.
The Geology of the Rolla Quadrangle. By WattacE LEE. Missouri
Bureau of Geology and Mines, XII. Pp. 117, pls. 12, figs. 17,
maps 2.
The area covered by this report is in the central Ozark region of
Missouri and includes Phelps and Dent counties. The strata described
include the Gasconade, Roubidoux, and Jefferson City formations.
The general horizon is of interest because it includes part of the Ozarkian
and the Canadian of Dr. Ubrich’s classification. The author follows
the usual classification, placing these beds in the Upper Cambrian. A
few erosion remnants of Carboniferous age are found in the northeastern
part of the area.
An interesting structural feature is found in a number of sink areas.
The author believes it was developed from the caving and subsequent
filling of solution cavities.
The economic products of this quadrangle are negligible and the
chief value of the report lies in its contribution to the general stratigraphy
of the region.
W. B. W.
Glass Sands of Oklahoma. By Frank BurtraM. Oklahoma Geol.
Survey, Bull. No. 10, 1913. Pp. 91, pls. 8, figs. 3.
Approximately one-half of this report is taken up with a general de-
scription of the glass industry. As the author is a chemist he has treated
chemical processes in glass production rather fully.
Notable glass sand deposits of the state are limited to three areas:
the Arbuckle Mountains, southeastern Oklahoma, and near Tahlequah,
826 REVIEWS
in the northeastern part of the state. The greatest deposits are in the
Arbuckle Mountains, in the Simpson formation of Ordovician age. This
formation is from 1,200 to 2,000 feet thick, and the sands outcrop at
four horizons. Five sections give an average thickness for the glass
sands of 248 feet. The supply of raw materials seems almost inexhaust-
ible but transportation facilities are lacking in most localities. In south-
eastern Oklahoma the Trinity sandstone at the base of the Cretaceous
carries commercial quantities of good glass sand, and several localities
are readily accessible. In the northeast the Burgen sandstone, which
has been correlated with the St. Peters, carries a 50-foot bed of high-
grade glass sand, but is too remote from railroads for present develop-
ment.
Analyses of these sands show that they compare very favorably
with deposits now being worked in adjacent states. Having a marked
advantage in the use of natural-gas fuel, Oklahoma sands should prove
strong competitors for the glass market of the central Mississippi Valley.
W. B. W.
Inland Lakes of Wisconsin. By Epwarp BIrRGE and CHANCY
Jupay. Wisconsin Geol. Survey, Bull. No. 27, 1914. Pp.
132, figs. 8, tables 4, maps 29.
A large portion of the data in this report has been published in
various bulletins scattered through a dozen years. It seemed desirable
to gather this material in a single volume, together with additional data
not published hitherto.
No lakes occur in the southwest or driftless area, and all the lakes
of the remaining three-quarters of the state are of glacial origin. In
general the lake basins were formed in four different ways: by melting
of blocks of ice imbedded in the glacial débris, by damming of preglacial
valleys, by interlocking of terminal moraine deposits, and by inequalities
in deposition of ground moraine.
The total number of lakes runs into the thousands, but only the
larger ones are described. There are 21 hydrographic maps, and with
each is a brief report on the geology and topography of adjacent regions
and the origin of the lake basins.
Tables give data on the locations of the lakes, their size, and the
depth and shape of their basins. Lake Winnebago with an area of 215
square miles is by far the largest in the state. Few of the lakes exceed
one hundred feet in depth. The United States Geological Survey has
——E——————<— << lh ee
REVIEWS 827
estimated the total lake area of the state at 810 square miles. The
authors believe that twice this amount is more nearly correct.
W. B. W.
_ Preliminary Report on Tertiary Paleontology of Western Washington.
By Cuartes E. Weaver. Washington Geol. Survey, Bull.
INOW TS.59r2. Pp. 80, pls. 15.
A Tertiary invertebrate marine fauna of 246 species is listed in this
report. Eighty-four of these are new species and are described and
figured for the first time. The fauna is very largely pelecypods and
gastropods.
Lower Eocene rocks are absent. The Upper Eocene fauna totals
79 species. The Oligocene fauna is limited to 10 species. A detailed
report will supplement this bulletin later and treat more fully of the
stratigraphic and structural relations.
W. B. W.
Geology of East Central Oklahoma. By L. C. SNiDER. Okla. Geol.
Survey, Bull. No. 17, 1914. Pp. 25, pls. 2, fig. 1.
The area treated in this report includes all of Haskell County and
portions of five adjoining counties. It deals with structural features
almost entirely and the stratigraphy given follows United States Geologi-
cal Survey reports.
About twenty anticline and syncline axes are plotted. Well-
drillers may locate the axes of anticlines roughly from this map and
supplement it by detailed work in each locality. For the convenience
of many who have not access to the annual reports of the United States
Geological Survey, the report includes a map and descriptions of the
principal folds in a region adjacent on the southwest. A number of wells
are producing gas in these two areas, but oil wells of importance have
not been reported.
W. B. W.
Ponca City Oil and Gas Field. By D. W. OHERN and R. E. Gar-
RETT. Okla. Geol. Survey, Bull. No. 16, 1912. Pp. 30, pls. 2,
1a 3
The Ponca oil and gas field is located in north-central Oklahoma near
the Kansas line. It produced gas only until 1911 when the first oil
828 REVIEWS
well was brought in. Thirty producing oil wells were operating at the
time this bulletin was written.
The report describes the formations of Lower Permian and Pennsyl-
vanian age that outcrop in the Ponca City area, and also those under-
lying that outcrop to the east and west. The structure of the Ponca
City anticline is shown by a contour map on the surface of the Herington
limestone.
It is the opinion of the authors that many of the wells labeled “dry”
are not deep enough to test their localities. Some holes do not go down
1,000 feet, and few below 1,600; but the approximate position of the
lowest oil sand is much deeper, and the anticline will not be tested
thoroughly until wells have reached the Tucker sands at a depth of
nearly 3,500 feet.
W. B. W.
The Mineral Springs of Saratoga. By JAmMes F. Kemp. New
York State Education Department, Bull. No. 517, 1912.
Pp. 79, figs. 8, tables 7.
There are few problems more difficult for geologists than those con-
nected with the origin of mineral springs. The district centering at
Saratoga Springs has long been famous for its mineral waters, and this
report has been prepared in response-to the very general interest regard-
ing them. The report takes up briefly a historical sketch of the springs,
the local geology, and a general description and classification of ground-
waters.
The chemical composition of the water is known by analyses of
three different periods, 1838, 1871, and 1905. These show a total of
ten acid and twelve basic ions. The most abundant salt is sodium
chloride followed by calcium, magnesium, and sodium bicarbonates.
The waters carry an average of two or three volumes of CO, in solution.
The sulphate ion is practically absent.
The author rejects any theory that attributes the springs to connate
waters, the absence of sulphates being the strongest chemical evidence
against such theories. The same geological section is faulted in many
other places in the Hudson and Champlain valleys, yet even uncar-
bonated brine springs are lacking elsewhere. The author’s conclusion
is that many of the mineral constituents, as the haloids, sodium car-
bonate, and the carbonic acid gas, are from deep-seated sources. The
tendency of dying volcanoes to give off abundant CO, and the occurrence
REVIEWS 829
within ten miles of the only purely volcanic rock in New York, Vermont,
or western Massachusetts support this theory. The carbonated waters
take on calcium and magnesium carbonates from the Little Falls dolomite
on their upward journey. This conclusion accords with the marked
tendency of economic geologists in the last decade to lay greater stress on
the importance of magmatic emissions.
W. B. W.
Coal Resources of District No. I (Longwall). By Girpert H. Capy.
Illinois Coal Mining Investigations, Bulletin No. 10, Urbana,
t915. Pp. 149, pls. 9, figs. 27, tables 24.
The Longwall District, comprising Bureau, Putnam, Marshall,
La Salle, and Grundy counties and the adjacent parts of Livingston,
Kankakee, and’ Will counties, an area of about 1,700 square miles,
contains nearly six billion tons of available coal and is one of the foremost
districts of the state in economic importance. This bulletin is con-
cerned with the stratigraphic and structural geology of the region, the
economic geology of the coals and accompanying strata, and with the
working data developed. The important beds are Nos. 2, 5, 6, and 7,
of which No. 2 has been extensively mined. These coals have been
studied in a large number of mines. The character of the coal beds and
their general structure have been worked out in detail, and many sections
through the productive coal measures have been tabulated. In addi-
tion to its value in connection with the coal resources, the bulletin is of
general interest in that it contains an outline of the geology of the La
Salle anticline, including Starved Rock, Deer Park, and the surrounding
country.
Aves Be
Coal Resources of District No. VII. By FRED H. Kay. Illinois
Coal Mining Investigations, Bulletin No. 11, Urbana, 1915.
Pp. 233, pls. 4, figs. 47.
District No. VII comprises Macoupin, Madison, St. Clair, Christian,
Montgomery, Bond, Clinton, Washington, Perry, Moultrie, Shelby,
Fayette, Marion, and parts of Sangamon, Macon, and Randolph counties,
an area of about 7,000 square miles, containing coal estimated at more
than forty-five billion tons in bed No. 6 alone. The stratigraphy of the
coal measures has been carefully studied, and numerous sections have
been measured and tabulated. Some interesting structures in the coal
830 REVIEWS
beds have been noted, and illustrated by a number of diagrams.- The
rocks of the area are confined to the Pennsylvanian, with comparatively
simple structure. No. 6 is the only coal bed producing important
quantities of coal.
An De Be
Notes on Geology of the Gulf of St. Lawrence. By J. M. CLarK.
New York State Museum, Bull. No. 158, pp. 111-20.
The author treats briefly of the geology of Entry Island. Of chief
interest is his description of a type of topography which he calls “‘dem-
oiselle.” The relief is due to numerous mammiform hills rounded
into softly contoured domes of striking symmetry. These domes are
caused by the erosion of small laccoliths.
W. B. W.
a _ ——
RECENT PUBLICATIONS
—SxirF, F. J. V. Annual Report of the Director to the Board of Trustees,
for the Year 1914. [Publication 181, Field Museum of Natural History,
Report Series, Vol. IV, No. 5. Chicago, January, 1915.|
.—Smito, W. D. The Mineral Resources of the Philippine Islands for the
Year 1913. [Division of Mines, P.I. Bureau of Sciences. Manila, 1914.]
—SPENCER, M. L. J. Données Numériques de Cristallographie et de Minér-
alogie. Tables annuelles de Constantes et Données Numériques de
Chemie, de Physique et de Technologie. [Paris: Gauthier-Villars et
Cie; Chicago: The University of Chicago Press, 1914.]
—STANSFIELD, E., AND CARTER, F. E. Products and By-Products of Coal.
[Canada Department of Mines, Mines Branch No. 323. Ottawa, 1915.]
—STEPHENSON, L. W. The Cretaceous Eocene Contact in the Atlantic and
Gulf Coastal Plain. Shorter Contributions to General Geology, 1914-J.
[U.S. Geological Survey, Professional Paper 90-J. Washington, 1915.]
, AND VEATCH, J. O. Underground Waters of the Coastal Plain of
Georgia. And a Discussion of the Quality of the Waters, by R. B. Dote.
[U.S. Geological Survey, Water-Supply Paper 341. (Prepared in co-oper-
ation with the Geological Survey of Georgia.) Washington, 1915.]
—SutTerR, H. Revision of the Tertiary Mollusca of New Zealand, Based on
Type Material. Part I. [New Zealand Geological Survey, Department
of Mines, Palaeontological Bulletin No. 2. Wellington, 1914.]
Revision of the Tertiary Mollusca of New Zealand, Based on Type
Material. Part II. [New Zealand Geological Survey, Palaeontological
Bulletin No. 3. Wellington, 1915.]
—TyrrELL, J.B. Gold-bearing Gravels of Beauce County, Quebec. [Trans-
actions of the American Institute of Mining Engineers. Toronto, 1915.]
Gold on the North Saskatchewan River. [Canadian Mining Insti-
tute Bulletin, February, 1915. Toronto, March, ro15.]
—U.S. Bureau of Mines. Fourth Annual Report of the Director of the Bureau
of Mines to the Secretary of the Interior. For the Year Ended June 30,
tg14. [U.S. Bureau of Mines, Washington, 1914.|
—Wape, A. The Supposed Oil-bearing areas of South Australia. [Geo-
logical Survey of South Australia, Department of Mines, Bulletin No. 4.
Adelaide, 1915.]
—Washington Academy of Sciences, Journal of the. Vol. V. (Baltimore:
Waverly Press.|
—Washington University Studies, Vol. II, Part I, No. t. [St. Louis, July,
1914.]
831
832 RECENT PUBLICATIONS
—WEGEMANN, C. H. The Coalville Coal Field, Utah. [U.S. Geological
Survey, Bulletin 581-E. Washington, 1915.]
—Whit_ErR, H. J. Soils of Massachusetts and Connecticut with Especial
Reference to Apples and Peaches. [U.S. Department of Agriculture,
Bulletin 140. Washington, April 5, 1915.]
—WILKMAN, W.W. Kvartara Nivaforandringar i Ostra Finland. Deutsches
Referat. [Bulletin No. 33 de la Commission Géologique de Finlande.
Helsingfors, April, 1912.]
—Wituams, M. Y. The Ordovician Rocks of Lake Timiskaming. [Canada
Department of Mines, No. 1542, Museum Bulletin No. 17, Geological
Survey, Geological Series No. 27. Ottawa, 1915.]
—wWisconsin Academy of Sciences, Arts, and Letters, Transactions of the.
Vol. XVII, Part II, Nos. 1-6. [Madison, 1914.]
—Woop, B. D. Stream-gaging Stations and Publications Relating to Water
Resources, 1885-1913. Part VIII. Western Gulf of Mexico Drainage
Basins. [U.S. Geological Survey, Water-Supply Paper 340-H. Wash-
ington, 1915.]
———. Stream-gaging Stations and Publications Relating to Water
Resources, 1885-1913. Part IX. Colorado River Basin. [U.S. Geo-
logical Survey, Water-Supply Paper 340-I. Washington, 1o915.]
Stream-gaging Stations and Publications Relating to Water
Resources, 1885-1913. Part X. The Great Basin. [U.S. Geological
Survey, Water-Supply Paper 340-J. Washington, 1915.]
—Wood, H. O. The Hawaiian Volcano Observatory. [Reprinted from the
Bulletin of the Seismological Society of America, Vol. III. No. 1, March,
1913. Hawaiian Volcano Observatory.]
The Seismic Prelude to the 1914 Eruption of Mauna Loa.
[Reprinted from the Bulletin of the Seismological Society of America,
Vol. V, No. 1, March, 1915. Hawaiian Volcano Observatory.]
VNDEX TO VOLUME XO
PAGE
Acadian Triassic, The. By Sidney Powers : he als EOS; 254
Andrews, E.C. Notes on the Structural Relations pemmenn Australasia,
New Guinea, and New Zealand
Appalachian Geosyncline, The Upper Deemer Delta ae thes By
Joseph Barrell. Review by V. O. T. :
Archean Geology of Rainy Lake Re-studied, The. By Andres C.
Lawson. Review by T. T. Q. :
Arkose Deposits, The Geological Significance atl Genetic Clsstetion
of. By Donald C. Barton :
Aroha Subdivision, Hauraki, Auckland, The Grates of the. By I.
Henderson, assisted by ir A. Bartrum. Review by T. T. Q. ;
Australasia, New Guinea, and New Zealand, Notes on the Structural
Relations between. By E. C. Andrews
Average Regional Slope, A Criterion for the Gubdinscion a Old hadi
Surfaces. By Leopold Reinecke . ; ‘
Barrell, Joseph. The Upper Devonian Delta of the Appalachian Geo-
syncline. Review by V. O. T.
Barton, Donald C. Notes on the Disinertation of Granite in Bee
———. The Geological Sos and Genetic Classification of
Arkose Deposits
Bastin, Edson S. Geology ai fe Pitchblende Ores of leoterader
Review by V. O. T. B
Bauer, L. A. The General Magnetic Sure of the Earth. Review by
RoC ME.
Becker, George F., saat ARETE L. Dey. Noten on the ee Borce ef
Growing Crystals
Berry, E. W. The Upper Gieiaceats and Bieeene Bloras! of South
Carolina and Georgia. Review by R.C.M. .
Beyer, S. W., and H. F. Wright. The Road and Concrete Matenals
of Iowa. Review by W.B.W. .
Bighorn Dolomite of Wyoming, Origin of el By, Eliot Blaceweldedt
Review by R. C. M. :
Birge,, Edward, and Chancey naa, Talend Takes of Wieconsia:
Review by NWaTBaEW 1
Blackwelder, Eliot. Origin of the Eeenore ipolomite a ees
Review by RACSVE: :
Bliss, Eleanora F., and Anna I. Paine, Relation of the WwW seeanckon
Mica-Gneiss to the Shenandoah Limestone and to the Octoraro
Mica-Schist, of the Doe Run—Avondale District, Coatesville nat:
rangle, Pennsylvania. Review by V. O. T. : '
833
751
407
309
834 INDEX TO VOLUME XXIV
Botanical Criterion of the Antiquity of the asec akaae A. ByE. W.
Sinnott :
Branner, John C. ('Gesioen Hlsmentar: Preparada con igience
especial aos Estudiantes Brazileiros e 4 Geologia do Brazil.
Review by R. T. C. hirnlaer th or eared
———. Orville A. Derby :
Branson, E. B. The Lower Embar oF Wrong and Tes Eauee
Brokaw, Albert D. A Stage Attachment for the eee: i Mi-
croscope
, and Leon 2 Sraith Zen Weather of a Harulende
Gabbro
Buddington, A. F. Byraphyiitizetion: Pinsticdt ion! ane Silicification
of Rocks around Conception Bay, Newfoundland :
Butters, R. M. Permian of ‘“Permo-Carboniferous” of the acter
Foothills of the Rocky Mountains in Colorado. Review by V. O. T.
Buttram, Frank. Glass Sands of Oklahoma. Review by W. B. W.
Cady, Gilbert H. Coal Resources of District.No. I (Longwall). Re-
view by A. D. B. :
Caimanoidea Visheri, A New Grocadilan From the Olipecene of South
Dakota. By Maurice G. Mehl
Calcium Carbonate, The Role of Inorganic Rpenee in the Deposition
of. By John Johnston and E. D. Williamson
Calvert, W. R., A. L. Beekly, V. H. Barnett, and M. A. Pishel. Galeer
of the Standing Rock and Cheyenne River Indian Reservation
North and South Dakota. Review by V. O. T. :
Cape Lisburne, Alaska, The Jurassic Flora of. By F. H. Kaowlont
Review of R. C. M. :
Capillarity, Some Effects of, on Oil Kectaulgtian: By Ales W. McCoy
Cement Materials and Industry in the State of Washington. By Solon
Shedd. Review by W.B.W. .
Central Ross-shire, Geology of the. By B. NT: Baath, L. Ww. Eineeman
E. M. Anderson, J. Horne, C. B. seen and R. G. Carruthers.
Review by T. aT. Go
Chabot, Georges. Le Revernant Ebiide sur une région dene Se
Jura méridional. Review by R.C.M. oe :
Clark, J. M. Notes on Geology of the Gulf of St. Barren Revie
by WaBoWs. sh . et! 2
Pere eae Ph.D. Gecloay. Physical hel Eustaneat Review by
See ae Geulogie anes! By Gharles Sehuchere Review by
Coal Resources of Beier NG. I (enerevally:| By Gilbert H. Cady.
Review by A. B. D. .
one ae ei of District No. VII. By Bred 5B Kay: Review or
Collins, W. H. The Eunonien Bontatinns a Thickening Region
Canada. Review by T. T. Q. aE hee ee
726
INDEX TO VOLUME XXIV
Corries, with Special Reference to Those of the Campsie Fells. B
_ J. W. Gregory. Review by R. C. M. ; . i
Crawford, R. D. Geology and Ore Deposits of the Moverch aiid
Tomichi Districts, Colorado. Review by V.O.T.. .
Cretaceous Deposits of the Eastern Gulf Region, and Species of Receen
from the Eastern Gulf Region and the Carolinas. re L. W.
Stephenson. Reviewby R.C.M. . .
Cristivomer namaycush, Great Lake Trout, Discovery as OG, in fie
Pleistocene of Wisconsin. By L. Hussakof
Cushing, H. P., and R. Riedemann. athe of ee Spring aad
Vicinity. Review by W.B.W. .
Day, Arthur L., and George F. Becker. Note on the Linear Force of
Growing Crystals Pe NERA One Ne Uestae Td eas nantes
Derby, Orville A., By John C. Biatiner
Disintegration of \Granite in Eeypt, Notes on the, By Donald C.
Barton Dewoe s ‘ Wane ; ; :
Eakin, Henry M. A Geologic Reconnaissance of a Part of the Rampart
Quadrangle, Alaska. Review by V. O. T. .
Earth, The General ee Survey of the. By L. A. eee Review
by R. C. M.
Eastern Gulf Region, Greceeis Drarests of ine atl Spent: i iexoeyea
from the Eastern Gulf Region and the Carolinas. oY W. L.
Stephenson. Reviewby R.C.M. ..
Ellipsoidal Lavas in the Glacier National Park, Montane: By Tae
caster D. Burling
Embar, The Lower, of Wyoming and its Fat auna. By, E. B. aiason
Florida, Origin of Hard Rock Phosphates of. ar E. H. Sellards.
Review by W.B.W. ...
Foerste, A. F., and W. C. Morse. The Woveda Fomintions of East
Central Kentucky. Review by W. B. W. :
Foliation in the Pre-Cambrian Rocks of owners New Yon Origin
of. By William J. Miller
Fossils from Limestone of Steeprock Tare Gntane Notes on. By
Charles D. Walcott. Review by T. T. Om
Foye, W. G. Are the ‘“‘Batholiths” of the Haliburton- Bancroft en
Ontario, Correctly Named? .
Fuller, Myron L. The eoneys of (oes Tela: New oi, Revi iew
by WeOsels rey! :
Garrett, R. E., and D. W. Ohern. Ponca City Oil and Gas Field.
Review by W. B. W. 5
Geologia Elementar. Preparada con H tcreren eSepial a aos Estudi. antes
Brazileiros e 4 Geologia do Brazil. Por John C. Branner. Review
by Rade 'C. Bilete ‘
836 INDEX TO VOLUME XXIV
Geological History of New York State. By William a3 Miller. Review
by W.B.W. .
Geological Map of Tene Compiled by Olaf Pp. qeskane (A. H
Purdue, State Geologist). Review by R. D. S..
Geologische Beobachtungen in Spitzbergen. Ergebnis der W. FE ne
schnerschen Vorexpedition nach Spitzbergen 1910. By Professor
H. Philipp. Review by T. T. Q. :
Geology and Geography of a Portion of aeaiet Gains panies
By Alfred Reginald Schultz. Review by V.O.T. . .
Geology and Ore Deposits of the Monarch and Tomichi Diseaes
Colorado. By R. D. Crawford. Review by V. O. T. :
Geology of Central Ross-shire, The. By B. N. Peach, L. W. nie eae
E. M. Anderson, J. Horne, CB: annie. and R. G. Carruthers.
Review by T. sie Q. ; 2” aah EES cil eee eae
Geology of East Central Oklnharia: By L. C. Snider. - Review by
WBS Wee F 5, Wt TC cee
Geology of Long Telia’ New ote The. By Myron L. Fuller.
Review by V. O. T. : Une
Geology of North Creek underage: By William l. Miller. Review
by W.B. We 2.
Geology of Saratoga Sas and aay, By H. P. Gicking a
R. Ruedemann. Review by W.B.W. .
Geology of Southeastern Ontario, The Pre- Cannan By Willet G.
Miller and Cyril W. Knight. Review by T. T. Q. :
Geology of Steeprock Lake, Ontario, The. By Abdrew C: Lawaeh
Review by T. T. Q.
Geology of the Aroha Sabdinedens aarakt Pmcelantl The. Ey
J. Henderson, assisted by J. A. Bartrum. Review by EO
Geology of the Gold Belt in the James River Basin, Virginia. By
Stephen Taber. Review by T. T.Q. .
Geology of the Gulf of St. Lawrence, Ndtes on. ee qf: M. Clark.
Review by W.B.W. :
Geology of the Pitchblende Ores at Golowda : By Baan S. acces
Review by V. O. T. ,
Geology of the Rabbit Ears Region, Routt, Grand and Tackenn Canes
Colorado, Reconnaissance of the. By F. F. Grout, P. G. Worcester,
and Junius Henderson. Review by V. O. T. sia. etree
Geology of the Rolla Quadrangle, The. By Wallace Lee. Review by
Wo BOW. oc
Geology of the Standing Rock and ‘Ghoseane River (adh Reservatianes
North and South Dakota. By W. R. Calvert, A. L. ae V. E
Barnett, and M. A. Pishel. Review by V.O, T. .
Geology, Physical and Historical. By H. F. Cleland, Ph.D. Review
by-AvG. i
Geomorphologie na Quast ive lone aes Sane ehirses Die By
Axel Hamberg. ReviewbyR.C.M. ...
Glaciology of the South Orkneys: Scottish National Anearette oes
dition. By J. H. Harvey Pirie. Review by T. T. Q. :
Glass Sands of Oklahoma. By Frank Buttram. Review by W. B. W.
INDEX TO VOLUME XXIV
Gletscher des Sarekgebirges und ihre Untersuchung, Die. By Axel
Hamberg. Review by R. C. M.
Gletschereises, Uber die Barallelewrakesa: aes, By Axel Hamberg
Review by R. C. M. : 5
Gold Belt in the James River asi “Witeeiey Geclony eo ite! By
Stephen Taber. Review by T.T.Q.. . ;
Grain of Igneous Rocks, The. By A. C. Lane. Revien by R. C. M.
Grandfield District, Oklahoma, Reconnaissance of the. By Malcolm
J. Munn. Review by V. O. T Bis er a are Se a ic
Granger, Walter, and W. J. Ginelain Paleocene Deposits of the San
Juan Basin, ‘New Mexico. Review by V. O. T. ola ge 2 ae One ears
Granite in Egypt, Notes on the Disintegration of. By Donald C.
Barton
Great Lake Trout, CaS vom: meray cushy ieeovery oh ie, in the
Pleistocene of Wisconsin. By L. Hussakof
Gregory, J. W. Corries, with Special Reference to Those of the Campsi
Fells. Review by R. C. M. :
Grout, F. F., P. G. Worcester, and Junius Henderson: Recon anes
of the Geology of the Rabbit Ears Region, Routt, Grand and Jack-
son Counties, Colorado. Review by V. O. T.
Growing Crystals, Note on the Linear Force of. By George F. Bestes
and Arthur L. Day. .
Gulf of St. Lawrence, Notes on Geology of he. By J: M. Clark.
Review by W.B.W. .
Gypsum Deposit in Iowa, A New. ‘2B y G. F. Kay: Bevery by 1 C. M.
Harker, Alfred. Differentiation in Intercrustal Magma Basins
Haliburton-Bancroft Area, Ontario, Are the “Batholiths” of the, Cor-
rectly Named? By W. G. Foye
Hamberg, Axel. Die Geomorphologie und Quartargeologie des carck
gebirges. Review by R. CINE
=. Die Gletscher des See eepirees wind ifr Untersuchung
Review by R. C. M. :
Kurze Ubersicht der Gletscher Schwedens. Reon by
R. C. M. ! sn pine ute
eee?) Uber. die Parallelstruktur fles eibeererecee! Review by
RCS Mis. Fhe 4
Hawkins, A. C. Toekatone Roanaton ae the Triassic of New Jey
and Pennsylvania. Review by RAC eM:
Haynes, Winthrop P. The Lombard Overthrust nnd ‘Related ices
logical Features f
Henderson, J., assisted by I: A. Bartram: "The Goleen of the Aedha
Subdivision, Hauraki, Auckland. Review by T. T. Q.
Henderson, Junius, F. F. Grout, and P. G. Worcester. Reconnaissance
of the Geology of the Rabbit Ears Region, Routt, Grand and rire
son Counties, Colorado. Review by V. O. T.
Heinrich, M. On the Structure and Classification of the Stromato:
poroidea UNE a: CAN pte 5X ; : Lita Peg
838 . INDEX TO VOLUME XXIV
Hobbs, William Herbert. Assumptions Involved in the Doctrine of
Isostatic Compensation, with a Note on Hecker’s Determination
of Gravity at Sea
Hornblende Gabbro, Zonal Weaheuns of a. RB, Albert D. Broan and
Leon:P. Smith >":
Huronian Formations of Pesiskarning Reion: Canada: The. By
W. H. Collins. Review by T. T. Q. : :
Hussakof, L. Discovery of the Great Lake Trout, Gestomer namay-
cush, in the Pleistocene of Wisconsin .
Hydrothermal Alteration, Studies in. I. By E. A. Sienheeean
Igneous Rock, the Composition of the Average. By Adolph Knopf.
Inland Lakes of Wisconsin. By Edward Huge and Chancey Jueey
Review by W.B.W.
Intercrustal Magma Basins, Paiecennntionlt in. Ey. Alfred Haricer
Isostatic Compensation, Assumptions Involved in the Doctrine of, with
a Note on Hecker’s Determination of Gravity at Sea. By William
Herbert Hobbs Lee 1) ae Cee Re
James River Basin, Virginia, eat of the Gold Belt in the. on
Stephen Taber. Reviewby T.T.Q.. .
Johnson, Douglas W. Studies for Students. Cautabicions to ene
Study of Ripple Marks .
Johnston, John, and E. W. Witliamncene The Réle aE Tngreanes Agen-
cies in the Deposition of Calcium Carbonate
Johnston, W. A. The Genesis of Lake Agassiz: A Gonsimacn
Jonas, Anna I., and Eleanora F. Bliss. Relation of the Wissahickon
Mica-Gneiss to the Shenandoah Limestone and to the Octoraro
Mica-Schist, of the Doe Run—Avondale District, Coatesville Quad-
rangle, Pennsylvania. Review by V. O. T. .
Juday, Chancey, and Edward pee Inland Lakes ee Wicconen
Review by W.B.W.
Jurassic Flora of Cape epee Aina The. By F. H. Knowles!
Review by R. C. M. : pt 8 ak ae
Kanawha County, West Virginia. By Charles E. Krebs. Review by
We Ve a ge
Karakoram Glaciers Gneneco ith Breese, Penecrally of ‘Aiiuents
Features of. By William H. Workman. "Review by R. C. M.
Kay, Fred H. Coal Resources of District No. VII. Review Py
AD Bs ke
Kay, G. F. A New ‘Gy patie eeostn in nia Review ie R. Cc. M.
Kemp, James F. The Mineral Springs of Saratoga. Review by
Wo BoW.-8
Knight, Cyril W., and Willet G. Miller. The eres Cambern Geology
of Southeastern Ontario. Review by ES TO:
Knopf, Adolph. The Composition of the Average igneous Rocks!
Knowlton, F. H. The gee Flora of se uh Tt Alaska.
Review by RCoM: 5 :
PAGE
690
200
726
685
180
620.
826
534
690
518
809
729
625
309
826
208
300
98
829
724
828
412
620
208
INDEX TO VOLUME XXIV
fa BW ae Kanawha County, West Virginia. Review by
Kurze Ubersicht der icles: Salinpadlans, By Axel Members
Review by R. C. M. i Hv Aiur cn eka sen
Lahee, Frederic H. Origin of the Lyman Schists of New Hampshire
Lake Agassiz, The Geneis of: A Confirmation. By W. A. Johnston
Lane, A.C. Mine Waters. Review by R. C. M ;
Temperature of the Copper Mines. Review by R. Cc. M.
———. The Grain of Igneous Rocks. Review by R. C. M.
Lawson, Andrew C. The Archean Geology of Rainy Lake Re-scudied!
Review ony BS 1054 0)3 :
———. The Geology of Stecprock Bakes One! Review by T. T. Q.
ow ee The Geology of the Rolla Quadrangle. Review By
Leonard, A.G. The ree. Wiecoucin Drift oi Noreh Dakota! :
Le Revermont, étude sur une région karstique du Jura méridional. By
Georges Cabot. Review by R. C. M.
Lincoln County, Wyoming, Geology and Geography of a Portion oh By
Alfred Reginald Schultz. Review by V. O. T. ;
Linear Force of Growing Crystals, Note on the. By, Genre F.
Becker and Arthur L. Day ..
Lockatong Formation of the Triassic of New Taser andl Penney are
By A. C. Hawkins. Review by R. C. M.
Lombard Overthrust and Related Geological Features, The. By
Winthrop P. Haynes St ee ee
Long Island, New York, The Geslory, of. By NIG ron itp Fuller. Re-
view by VeO ne:
Lyman Schists of New Hampshire Origin Bn the. By Frederic H.
Lahee. bi noe ane elas
McCoy, Alex. W. Some Effects of Capillarity on Oil Accumulation
Magnetic Survey of the Earth, The General. By L.A. Bauer. Review
yen CVs ate meh eax emus iey SPE,
Marshall, P. Oceania. Reweu ye R. Cc. M. :
Mehl, Maurice G. Caimanoidea Visheri, A New Grocoailinn fo the
Oligocene of South Dakota
Metallographic Microscope, A Stage Avartnaatt for the. By Albert
D. Brokaw : : ; :
Mexico, The EN soeta phy, a iB Wermen N. Tinaer E
Miller, Willet G., and Cyril W. Knight. The Pre-Cambrian Gecloey
of Southeastern Ontario. Reviewby T.T.Q.. .
Miller, William J. Geological History of New York State. Review by
W. B. W.
Sh Calan GE North Creek @uacrancls Revere by W. B. W.
—— —, Origin of Foliation in the Pre-Cambrian Rocks of Northern
New York SESS POET ee BT ac hs aaa
Mine Waters. By A.C. Lane. Review by R. C. M.
840 INDEX TO VOLUME XXIV
Mineral Springs of Saratoga, The. By James F. Kemp. Review by
PAGE
W. B. W. oes
Mississippian Eeachenpadn of a Mississippi Valley Base The. By
Stuart Weller. Review by J. W.B. . 95
Molengraaff, G. A. F. On Oceanic Deep: oy Deposits a Cantedl
Borneo. Review by R.C.M. . 405
Monarch and Tomichi Districts, Geology ma Gre inenostes of the: By
R. D. Crawford. Review by V. ©. T; : 408
Monocyclic Crinoidea Camerata, Evolution of the Basal Plates in. By
Herrick E. Wilson . f ; . 488, 533, 665
Morse, W. C., and A. F. Rocrier The Waverlian F ormations of East
Central Kentucky. Review by W: B. W. 824
Mud Lumps at the Mouths of the Mascccinae The. Be Raves W.
Shaw. Review by R. C. M. : 623
Munn, Malcolm J. Reconnaissance of the Grandeeld Dicmiee Okla-
homa. Review by V. O. T. TET es
New Gypsum Deposit in Iowa,A. ByG.F.Kay. ReviewbyR.C.M. 724
Niagaran Formations of Western Ohio, The Classification of the. By
Charles S. Prosser ; 2, ae eee
Nochmals zur Frage der Glagaibidenpent in re Rhén. Erwiderung auf
die Ausfiihrung von A. Penck und Ed Briickner. By Hans Phillip.
Review by R. C. M. ae eer Meee me) fi ee TS
North en seaneee ee of. By William J. Miller. Review
by W. B. W. sy _*
: Nan .1cAfiReny. *-y. AAA? Ve
pe
a Aa
: ee pita, A FY VAY Y Wraneta®
ation EAI le nf pninak
ogy va “ & 2 A at 36 aR a= =
a "a f Wien Whale ae Paral w ba Tien 2 me 2 f
Seece! fh Rey ohne iW 2 HEE
HTT aeeee ROLY Civic sWPanknul gn ae ator t8
- q Ps NN Anne A : = :
i 9) Le Nea. olotal 1
"s Seerier aa ony ie am
agp Oa ahha AA Rae . 4 ve ms rte F HVT
-= cake, te Tale Rees bas
oT atl ean A aa q af veNINa \, Na \ hers
SAA aA BS pA ; ite AM,
svonennnne ltl atitonatiantees
CULUSS rag “TENT | PTL TT AD ag
Th = iguana age > ver
Sh eh did tpt d te a th Am - ‘Toms ile Bi ahah naan «
pv ‘i apapake: abP BAAR? Nf XB 4: ALDER ER | pana Aaiy
a .28, 068! j 71? ;
Ways: /Il ubedg ee n TTT Yee NHS My, yuculdtie
3 9088 01367 0138
a £3 fy A. id a2 fl a i
PALL | WARS s 4 am) WE n be el iy Re af | gaasas. te
~~ ey 1D Da» = ak a” The Mt Th eet. wh, a Van Mees: *, 4 a be # a Neue Swit f tigi
rT mA asses... @ AMIR Chee tg! BARE Ee an oe
“a9 Pas ; San" e= T11yreear s aoe Ua Tt {tery me “sa. pr’ le ig viata in anna
a \> 1 ern f AaAneas ’ rire ALY ay) tee nds a & z a h 5. areas
74g ba tos © 4 4
ARON € Pa “ae == ae,
Lary een Kans ageaaGhe, ADa PP eapcentt larry ye
mews | Tre TTT ULF pa RA AS TCTNCSO aces a ODS
SOT pee aes Me WaT TEN Fis hoi ae rePLTT CG
© 4 ry ee )
i ian wi “pygiP” “ er Gok oy. OSM
' * ane
eT iat Lywunyi aS
= i]
nt yaa
pid
ON Mea
heir we ee
_-=S ihe
ao OS ar ~ —) 57 ee eos
yas ~ awe ner o- e> 3 eT
Bi Pi, . j yt v
ana
BUTT a o,”' Pen at 3
corbuun’ a," m6
]