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FOURNAL OF GEOLOGY

A Semi-Quarterly Magazine of Geology and
Related Sciences

EDITORS
T. C. CHAMBERLIN, zz General Charge

R. D. SALISBURY R. A. F. PENROSE, Jr.

Geographic Geology Economic Geology
ALBERT JOHANNSEN C. R. VAN HISE

Petrology Structural Geology
STUART WELLER W. H. HOLMES

Paleontologic Geology - Anthropic Geology

S: W. WILLISTON, Vertebrate Paleontology
ASSOCIATE EDITORS

SIR ARCHIBALD GEIKIE G. K. GILBERT

Great Britain Washington, D. C.
H. ROSENBUSCH H. S. WILLIAMS

Germany Cornell University
CHARLES BARROIS CLD WAL COdaE

France U.S. Geological Survey
ALBRECHT PENCK J. C. BRANNER

Germany Stanford University
HANS REUSCH W. B. CLARK

Norway Johns Hopkins University
GERARD DE GEER O. A. DERBY

Sweden Brazil

Wi ee DAVE)
Australia

Les Aiaian nti

VOU MIE YaIrE

The Gnibversity of Chicago Press
CHICAGO, ILLINOIS

Published
February, March, May, June, August, September,
November, December, 1911

Composed and Printed By
The University of Chicago Press
Chicago, Illinois, U.S.A.

CONTENTS OF VOLUME XIX

NUMBER I

CLIMATE AND PHYSICAL CONDITIONS OF THE KEEWATIN. A. P. Coleman

THE AGENCY OF MANGANESE IN THE SUPERFICIAL ALTERATION AND
SECONDARY ENRICHMENT OF GOLD Deposits. William H. Emmons

LocaL DECOMPOSITION OF ROCK BY THE CORROSIVE ACTION OF PRE-
GuaciAL PEAt-Bocs. Edwin W. Humphreys and Alexis A. Julien

THE Focus oF Post-GLaciAL Uptirr NorTH OF THE GREAT LAKES.
J. W. Spencer : : 4 ‘ : A : :

A GEOLOGICAL RouTE THROUGH CENTRAL AstA Minor. William T.
M. Forbes , 3 s : ; -

THE VARIATIONS OF GLACIERS. XV. Harry Fielding Reid

REVIEWS

NUMBER II

THE SOUTHERLY EXTENSION OF THE ONONDAGA SEA IN THE ALLE-
GHENY REGION. E. M. Kindle
THE MISSISSIPPIAN-PENNSYLVANIAN UNCONFORMITY AND THE SHARON
CONGLOMERATE. G. F. Lamb : ;
THE WICHITA FORMATION OF NORTHERN Texas. C. H. Gordon,
George H. Girty, and David White 5 : :
NOTES ON THE OSTEOLOGY OF THE SKULL OF ParRioTIcHus. E. B.
Branson
HicH TERRACES AND ABANDONED VALLEYS IN WESTERN PENNSYLVANIA.
Eugene Wesley Shaw
REQUISITE CONDITIONS FOR THE FORMATION OF ICE RAMPARTS.
William H. Hobbs 2 : : ,
THE TERMINAL MORAINE OF THE PUGET SOUND GLACIER. J. Harlen
Bretz
EDITORIAL:
(hips SEEDING OF WoRLDS. I. C. C:
ARTESIAN WATERS OF ARGENTINA. B. W.

PETROGRAPHICAL ABSTRACTS AND REVIEWS
REVIEWS

61
83
go

97
104
110
135
140
157
161

175
178
181
189

vl CONTENTS OF VOLUME XIX

NUMBER III
CERTAIN PHASES OF GLACIAL Erosion. Thomas C. Chamberlin and
Rollin T. Chamberlin ; : ; , ;
VALLEY Frinuinc By INTERMITTENT STREAMS. A. E. Parkins .
ORIGINAL IcE STRUCTURES PRESERVED IN UNCONSOLIDATED SANDS.
Charles P. Berkey and Jesse E. Hyde
RESTORATION OF SEYMOURIA BAYLORENSIS BROILI, AN AMERICAN
Cotytosaur. S. W. Williston
GEOLOGIC AND PETROGRAPHIC NOTES ON THE REGION ABOUT CAICARA,
VENEZUELA. T. A. Bendrat
Tar AGE OF THE TYPE EXPOSURES OF THE LAFAYETTE FORMATION.
Udward W. Berry

Ti. RIPPLES OF THE BEDFORD AND BEREA FORMATIONS OF CENTRAL

AND SOUTHERN OHIO, WITH NOTES ON THE PALEOGEOGRAPHY
oF THAT Epocu. Jesse E. Hyde

A PosstpLtE LIMITING EFFECT OF GROUND-WATER UPON EOLIAN
Erosion. Joseph E. Pogue

RECENTLY DISCOVERED Hot SPRINGS IN ARKANSAS. A. H. Purdue
REVIEWS
PETROLOGICAL ABSTRACTS AND REVIEWS

NUMBER IV

MacMAtic DIFFERENTIATION IN Hawai. Reginald A. Daly
PETROGRAPHIC TERMS FOR FIELD Use. Albert Johannsen

THE EvoLutIonN oF LIMESTONE AND Dotomite. I. Edward. Steidt.
mann

THE RECURRENCE OF TROPIDOLEPTUS CARINATUS IN THE CHEMUNG
FAUNA OF VIRGINIA. E. M. Kindle

FURTHER DATA ON THE STRATIGRAPHIC POSITION OF THE LANCE
FORMATION (‘‘CERATOPS BEpDs’’). F. H. Knowlton .

LARGE GLACIAL BowWLpERS. George D. Hubbard .
REVIEWS

NUMBER V

SAMUEL CALVIN. H. Foster Bain .

THE EVOLUTION OF LIMESTONE AND Dotomite. II. Edward Steidt-
mann

PAGE

193
217

223

232

238

249

Boy

270
272
276
283

289
317

323
346
358

Sil
381

385

392

CONTENTS OF VOLUME XIX

THE DIFFERENTIATION OF KEWEENAWAN DIABASES IN THE VICINITY
or LAKE Nipicon. E. S. Moore

GENERA OF MISSISSIPPIAN Loop-BEARING BRACHIOPADO. Stuart
Weller

PHYSIOGRAPHIC STUDIES IN THE SAN JuAN District oF COLORODA.
Wallace W. Atwood

THE VARIATIONS OF GLACIERS. XVI. Harry Fielding Reid .
PETROLOGICAL ABSTRACTS AND REVIEWS
REVIEWS

NUMBER VI

PRELIMINARY STATEMENT CONCERNING A NEW SYSTEM OF QUATER-
NARY LAKES IN THE MIssIssippI Basin. Eugene Wesley Shaw

GRAVEL AS A RESISTANT Rock. John Lyon Rich .

THE CRETACEOUS AND TERTIARY FORMATION OF WESTERN NORTH
DAKOTA: AND EASTERN Montana. A. G. Leonard

ON THE GENUS SYRINGOPLEURA SCHUCHERT. George H. Girty

PRELIMINARY Notes on Some IcNEous ROCKS OF Japan. I. S. Koézu

PRELIMINARY NoTES ON SoME IGNEOUS Rocks oF JAPAN. II. S.
Kozu : d : : : :

PRELIMINARY NOTES ON SOME IGNEOUS Rocks oF JAPAN. III. S.
Kozu

REVIEWS

NUMBER VII

THE Iowan Drirr. Samuel Calvin

THE THEORY OF Isostasy. Harmon Lewis : : ;

SPECULATIONS REGARDING THE GENESIS OF THE DIAMOND. Orville A.
Derby : ; , : : : : : :

PRELIMINARY NOTES ON SOME IGNEOUS Rocks OF JAPAN. IV. S.
Kozu ; : : :

FACTORS INFLUENCING THE ROUNDING OF SAND GRAINS. Victor
Ziegler : : : 4 :

THE UNCONFORMITY BETWEEN THE BEDFORD AND BEREA FORMATIONS
OF NORTHERN Onto. Wilbur Greeley Burroughs

Vil

PAGE
429
439
449

454
462

469

481
492

597

548
555

561

566
576

Saal
603

627
632
645

655

Vill CONTENTS OF VOLUME XIX

EDLLORTAL Gs CG.
REVIEWS ;
RECENT PUBLICATIONS .

NUMBER VIII

Tue BEARINGS OF RADIOACTIVITY ON GrEoLocy. T. C. Chamberlin

THE WING-FINGER OF PTERODACTYLS, WITH RESTORATION OF
Nycrosaurus. S. W. Williston

THE TERRESTRIAL DEPOSITS OF OWENS VALLEY, CALIFORNIA. Arthur
C. Trowbridge i ; :

On CoRUNDUM-SYENITE (URALOSE) FROM Monrana. Austin F.
Rogers

A DrRaAwiInc-BoaRD WITH REVOLVING DISK FOR STEREOGRAPHIC
Projection. Albert Johannsen

REVIEWS i
INDEX TO VoL. XIX

~ VOLUME. XIX NUMBER |

THE

JOURNAL or GEOLOGY

A SEMI- QUARTERLY

EDITED BY

THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
With the Active Collaboration of

SAMUEL W. WILLISTON ALBERT JOHANNSEN WILLIAM H. EMMONS

Vertebrate Paleontology Petrology Economic Geology
STUART WELLER WALTER W. ATWOOD ROLLIN T. CHAMBERLIN
Invertebrate Paleontology Physiography Dynamic Geology

ASSOCIATE EDITORS
SIR ARCHIBALD GEIKIE, Great Britain GROVE K. GILBERT, National Survey, Washington, D.C.

HEINRICH ROSENBUSCH, Germany CHARLES D. WALCOTT, Smithsonian Institution
THEODOR N, TSCHERNYSCHEW, Russia HENRY S. WILLIAMS, Cornell University
CHARLES BARROIS, France JOSEPH P.IDDINGS, Washington, D.C.
ALBRECHT PENCK, Germany JOHN C, BRANNER, Stanford University

HANS REUSCH, Norway R. A. F. PENROSE, Philadelphia, Pa.

GERARD DeEGEER, Sweden WILLIAM B. CLARK, Johns Hopkins University
ORVILLE A. DERBY, Brazil WILLIAM H. HOBBS, University of Michigan

T. W. E. DAVID, Australia FRANK D. ADAMS, McGill University

BAILEY WILLIS, Argentine Republic CHARLES K,. LEITH, University of Wisconsin

JANUARY -FEBRUARY, 1011

CONTENTS
CLIMATE AND PHYSICAL CONDITIONS OF THE KEEWATIN - - - A. P. Coreman I
THE AGENCY OF MANGANESE IN THE SUPERFICIAL ALTERATION AND SECOND-
ARY ENRICHMENT OF GOLD DEPOSITS - - - - - - - Witiram H. Emmons = 15
LOCAL DECOMPOSITION OF ROCK BY THE CORROSIVE ACTION OF PRE-GLACIAL
PEAT-BOGS - - - - - - - - - - -Epwin W. Humpureys anp ALExIs A. JULIEN 47

ON THE FOCUS OF POSTGLACIAL UPLIFT NORTH OF THE GREAT LAKES
J. W. SPENCER 57

A GEOLOGICAL ROUTE THROUGH CENTRAL ASIA MINOR ~~ Wrtitam T.M. Forses 61
THE VARIATIONS OF GEACIERS. XV -- - -..- -,- = = - “HArRy FIeELpine REID “© .83
PLETE Sis g CS a 9 eS ASE Nite 9 he ages, ee eh cass

Che University of Chicago Press
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WILLIAM WESLEY & SON, Lonpon
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ERRATA

In the article by James H. Gardner, published in No. 8, 1910,
of this Journal, the following errata should be noted:

Plate I, between pages 702 and 703, belongs to the preceding
paper, by Messrs. Ball and Shaler.

Plate II, between pages 742 and 743 in the paper by Mr. Robin-
son, belongs between pages 708 and 709. |

Label for Fig. 3, p. 716, is for Fig. 7, p. 724.
Label for Pigs 4,ip. 728. 1s tor Mig. a7 oO:
Label for Fig: 5,<p: 720, 1s for Fig. 4, p. 726:
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Label for Fig. 7, p. 724, is for Fig. 6, p. 722.

FOURNAL OF GEOLOGY

VANCATKN— FPEBROAR VG TOR

CLIMATE AND PHYSICAL CONDITIONS OF THE
KEEWATIN

A. P. COLEMAN,

Toronto

CONTENTS
INTRODUCTION

THE KEEWATIN ERUPTIVES

KEEWATIN SEDIMENTS

THE TRON FORMATION IN ONTARIO

RELATIONS OF THE KEEWATIN TO THE GRENVILLE SERIES
CONCLUSIONS

INTRODUCTION

It is intended in this paper to bring together evidence which
has been accumulating during recent years as to the climate and
general physical conditions of the Keewatin. Most of this evi-
dence has to do with the sedimentary rocks of this age in western
and northern Ontario, and a considerable part of it has been
obtained by myself and my assistants in mapping the iron ranges
of the province for the Bureau of Mines of Ontario.

Not long ago the pre-Cambrian as a whole was looked on as a
geological “‘no man’s land,” full of doubt and difficulty because
of the obscurity of its relations. Now, however, the succession
as far as the base of the Huronian has been worked out in detail
in several areas of the pre-Cambrian in America; and we find that
the source of these rocks and their general relations are entirely
Vol. XIX, No 1 I

2 A. P. COLEMAN

similar to those of later, fossiliferous, series. ‘The mystery has
largely departed from them.

So far as the Huronian or Algonkian is concerned everyone
admits that the rocks, both sedimentary and eruptive, were formed
like those of later times. It is true that the absence of fossils in
the east and their great rarity in the West is a puzzle; but all agree
that the pre-Cambrian seas were not so different from later waters
as to be uninhabitable, and that forces at work in the Huronian
did not differ materially from those which formed the Cambrian
or later rocks.

To have this brought concisely before one it is only necessary
to read Van Hise and Leith’s late edition of the pre-Cambrian
geology in North America, a work of admirable completeness and
impartiality, summing up a literature of appalling dimensions.
The former chaos has then been so far set in order that we find
evidence in Huronian or Algonkian times of climates not unlike
those of later ages, when wind and weather, flowing rivers and
beating waves, and even great ice sheets did their regular work.
In northern Ontario glaciers formed bowlder clay in lat. 46°, show-
ing no hint of the action of primeval heat, such as the usually
accepted version of the Nebular Hypothesis demands.

But there is much less certainty and much less unanimity
regarding pre-Huronian times. The Huronian is cut off from the
underlying rocks by one of the greatest known discordances.
During the interval left unrecorded in this great unconformity
the previous rocks were raised into mountains, metamorphosed by
the action of intrusive granite and gneiss, and then profoundly
eroded. ‘The proofs of this are to be found in the bowlders of the
Huronian tillite, which include all the lower rocks in their present
metamorphosed conditions; and in the hummocky plain formed
from the previous mountain ranges which in many places underlies
the little-disturbed Huronian.

The world was already very old and had undergone many vicissi-
tudes before the Huronian ice sheets began their work. What
light can be thrown on the vast and vague pre-Huronian time ?

Many geologists have been inclined to see in the underlying
“basal complex,’’ or Urgebirge, portions of the earth’s original

CLIMATE AND PHYSICAL CONDITIONS OF KEEWATIN 3

crust or its downward extension. For example, Rosenbusch in
the new edition of his Elemente der Gesteinslehre speaks of the
crystalline schists underlying all later rocks as representing, at
least in part, the earth’s erste Erstarrungskruste. Like some
others of the older geologists he still holds to the Nebular Hy-
pothesis and looks on the basal complex as having been formed
at the stage when the molten earth had so far cooled as to consoli-
date on the surface, producing plutonic rocks’ and crystalline
schists. According to this hypothesis it was still too hot to per-
mit the condensation of water, so that no rivers or oceans were
possible. |

Elaborate theories of continent- and mountain-building are still
founded on this idea of the earth’s progressive cooling, and it is
hard for geologists brought up like the present writer on the fiery
diet of a Nebular Hypothesis as an introduction to historic geology
to rid their minds of so firmly imbedded a prepossession. That
astronomers also are afflicted with these bad dreams is plain from
certain recent popular writings on the history of Mars as com-
pared with earth. The conviction is however growing in the minds
of many geologists that even the pre-Huronian or Archaean can-
not be looked on as exceptional; that the Huronian basal conglom-
erate means a break in time, but no break in the continuity of
marine and terrestial processes; that the affairs of the world were
conducted in the same way before this great interval as after it.

Evidence of various kinds in favor of this will be given in sub-
sequent pages.

THE KEEWATIN ERUPTIVES

“The basal complex’? of the western lakes region was split
up many years ago by Lawson into the Laurentian granites and
gneisses and the Keewatin, the latter looked on as consisting essen-
tially of eruptives. In the original Keewatin region on Lake-of-
the-Woods eruptive rocks are in great preponderance, though
Lawson recognized the presence of subordinate amounts of sedi-
ments, which will be referred to later.

These eruptives are chiefly basic—now mostly transformed

1Op. cit., 35.

4 A. P. COLEMAN

into greenstones and green schists; but there are acid rocks in
important amounts—quartz porphyries, felsites, etc., and their
schists. In a number of places these eruptives were lava flows
showing pillow and amygdaloidal structures, and often pyroclastic
materials accompanied the outbreaks of lava. It is probable
that most of the characteristic Keewatin eruptives were volcanic,
though the squeezing and shearing they have undergone often
obscure their origin as lavas or ash rocks. Undoubted plutonic
rocks occur among these surface eruptives, but often they can’
be proved to be much later in age, since they have penetrated the
other rocks and carried off fragments of them.

There are also many dikes of both basic and acid rocks cutting
the volcanics, and there were probably laccolithic sheets and
masses invading them; but later mountain-building processes,
connected mainly with the elevation of granite batholiths, have
greatly obscured the relationships. While terrestrial lava flows
and falls of bombs and ashes played the most prominent part in
the formation of the Keewatin in many places, submarine lava
flows may have taken place also, since the pillow structure is
generally regarded as resulting from the action of water on hot
lava streams. ‘There is every reason to suppose that then as now
there were volcanic eruptions both on land and from the sea bottom.

Through what substratum these volcanic rocks came to the
surface is unknown. At present they commonly rest on the
gneiss and granite of the Laurentian—deep-seated eruptives of a
later age, which have invaded and swept off fragments of the
Keewatin rocks in ways showing that they were cold and solid at
the time. The floor on which the lavas flowed and the volcanic
ashes were rained down has generally vanished, though in places
the volcanics rest on sedimentary schists or gneisses of the
Couchiching, which will be described later.

In most cases the old volcanoes themselves have disappeared,
but the base of one of them, consisting of gabbro, anorthosite, and
granite, has been described by Lawson, from Shoal Lake east of
Rainy Lake.

It was an age of intense volcanic activity, and the results were
just such as we find in the Keweenawan and more recent eruptive

CLIMATE AND PHYSICAL CONDITIONS OF KEEWATIN 5

periods; though the rocks are of course far more altered by meta-
morphism.

The Keewatin of the states near Lake Superior is described as
consisting almost entirely of eruptives such as have been referred
to above, though bands of iron range rocks occur with them in
Minnesota. President Van Hise and others therefore look on the
Keewatin as essentially eruptive with the exception of the oldest
iron ranges.

It will be shown in succeeding pages that this is by no means
true of the Keewatin of Ontario.

KEEWATIN SEDIMENTS

When Lawson began his study of the Lake-of-the-Woods region
he was specially impressed. with the wide-spread eruptives and ash
rocks, though he found associated with them subordinate amounts
of sediments such as carbonaceous slates and quartzites; and he
defined the Keewatin as essentially an eruptive series. As his
work extended eastward, however, he made the acquaintance on
Rainy Lake of a great series of sedimentary rocks, to which he gave
the name of Couchiching.

The correlation committee which adjusted the terminology of
the western Great Lakes region chose the name Keewatin instead
of Couchiching for the whole series; so that the Keewatin as now
defined includes both eruptives and sediments older than the
Laurentian.

By Lawson and later workers in northern Ontario it has been
shown that every type of water-formed sedimentary rock is rep-
resented in the Keewatin: limestones and dolomites, carbonaceous
and ordinary slates, mica schist and gneisses representing more
altered muddy sediments, quartzites, arkoses, and graywackes, and
even conglomerates and breccias, though the last-mentioned
rocks are not always easily separated from agglomerates, etc., of
volcanic origin. :

With the exception of the Couchiching, most of these sedi-
mentary rocks are not extensively developed in the region studied
by Lawson; iron formation occurs only in small outcrops and
remained unobserved in the hasty field work of early days.

6 A. P. COLEMAN

In reality the iron formation is found in practically every Kee-
watin area, always near the top of the series, and sometimes with
a thickness of 1,000 or 1,500 feet.

The iron formation differs so much from later sediments that
some geologists regard it as something peculiar and apart, belong-
ing perhaps to the earth’s earliest times and produced only under
conditions very different from those of the present. It has been
described, for instance, as a chemical sediment deposited in: a hot
sea where volcanic eruptions were taking place. So many specu-
lations have been indulged in on this fascinating subject that too
much space would be required to recapitulate them.

In many places in Ontario, however, the iron formation is so
closely associated with commonplace sedimentary materials, slate
charged with carbon, arkose, and crystalline limestone, that one
can hardly believe it to have been formed under peculiar condi-
tions not repeated in later times.

In any case the other sedimentary rocks, often covering large
areas and with considerable thickness, must be looked on as normal
products of conditions which have persisted ever since.

In the following pages descriptions will be given of the chief
Keewatin sedimentary rocks, and their distribution will be out-
lined. As the iron formation, because of its economic importance,
has been most carefully studied, it will be taken up first.

THE IRON FORMATION IN ONTARIO

In the states near Lake Superior the Keewatin iron formation
consists mainly of jasper of varying colors closely interbanded with
hematite, less often magnetite. Iron formation of a very similar
kind has been found between the Vermilion range in Minnesota
and Fort William on Lake Superior, and in smaller areas near
Batchawana Bay, Lake Temagami, and in a number of other places
in northern Ontario. More commonly in Ontario, however, the
silica is in the form of chert, quartzite, or a sandstone-like aggre-
gation of grains, while the interbanded iron ore is mostly mag-
netite. Probably the differences are largely due to more exten-
sive metamorphism in the latter as compared with the former type.

In most of the regions of Ontario where the iron formation has

CLIMATE AND PHYSICAL CONDITIONS OF KEEWATIN 7

been carefully mapped and studied it includes also more or less
siderite, or pyrite, or pyrrhotite, so that not the whole of the iron
is contained in the oxides.

There is, however, another variety of the formation which has
received less attention, consisting of granular silica with little or
no iron, but sometimes interbanded with gray or green schistose
materials. This appears to be the common form in the far west,
near Fort Frances on Rainy River, and near Kenora on the Lake-
of-the-Woods. In these localities sandstone-like rocks are found
quite extensively with the gray schists described by Lawson as
Couchiching. It may be that the sources of iron ran out toward
the west, leaving only the silica.

The sandstone-like variety of iron formation, when first found
by the present writer, was thought to be an ordinary sediment.
It resembles a white or gray or brownish sandstone of even grain,
and is often so loosely cemented that the rock may be crumbled
in the fingers. Thin sections, however, show little or no clastic
structure. The quartz grains are polyhedral individuals which
have grown from centers until they met. Every transition may
be found between these relatively coarse-textured varieties and
the very fine-grained silica, often chalcedonic, of the jaspers. The
quartzitic variety occurs in or near the eruptive granite of the
Laurentian. In it the anhedra of quartz are firmly cemented
together.

As mentioned before, in most places in Ontario the silica and
iron ore are accompanied by ordinary sedimentary material. In
a number of thin sections sillimanite occurs, a silicate of alumina
that must have been recrystallized from clay. On the east shore
of Lake Nipigon, and in other places, the banded silica and mag-
netite are interbedded with gray slate or phyllite and often pass
gradually into this rock, which is, of course, a metamorphosed
clay. Frequently also a few feet of black carbonaceous slate
underlie the iron formation, as at the Helen mine, Michipicoten,
and at Grassy Portage on Rainy Lake.

At Goudreau Lake southwest of Missanabie, the iron formation
contains a small amount of granular silica with magnetite, and a
large amount of pyrite, the sulphide replacing the oxide; and

Sat A. P. COLEMAN

parallel with it runs a band of crystalline limestone 30 feet thick
and more than a mile long.

In the cases just mentioned sediments such as clay, limestone,
and carbon were deposited with silica and iron oxide or sulphide.
The carbon makes it altogether probable that sea weeds lived on
the muddy bottom, so that the waters must have been cool enough
for life and free from poisonous substances.

In a number of places near Lake Nipigon the iron ranges include
large amounts of arkose as well as the slaty rocks mentioned above.
Thin sections present the usual angular or subangular fragments of
quartz and feldspar imbedded in a finer grained matrix. The forma-
tion of these greenish gray arkoses suggests a land surface of granite
or gneissoid rocks exposed to weathering in a cool and moist
climate, as shown by Professor Barrell, in his excellent study of
Climates and Terrestrial Deposits. ‘These rocks cover in all many
square miles and must have a thickness of a thousand feet or more,
unless greatly reduplicated by folding. Near Poplar Lodge they
have a width of a quarter of a mile with dips of from 60° to 80°,
though banded jasper and hematite and also a little green schist
are interleaved with the arkose, making up perhaps one-tenth of
the whole.

THE COUCHICHING PHASE OF THE KEEWATIN

Associated with the iron formation at a number of points on
Rainy Lake, Rainy River, near Dryden, etc., one finds gray fine-
grained schists and gneisses having the character of the Couchich-
ing as described by Lawson; but these rocks occur in larger areas
apart from known iron ranges. They are composed of quartz,
biotite, sometimes muscovite, and often some orthoclase or pla-
gioclase; and they frequently contain sillimanite, garnet, and
staurolite, or pseudomorphs after staurolite. They are evidently
sandy or clayey sediments recrystallized, and may be compared
with the sedimentary gneisses and quartzites of the Grenville series
of eastern Canada so well described by Adams.

The materials of which they were formed must have been
derived from granite or gneiss and not from the basic eruptives
with which they are associated. In the decay of the original rocks
much of the feldspar must have been decomposed, the alkalies

CLIMATE AND PHYSICAL CONDITIONS OF KEEWATIN 9

being removed. They are often seen resting on Laurentian gneiss,
but the latter was not the source of the sand of which they were
formed, since the Laurentian is everywhere in eruptive relation-
ships with the Couchiching and hence is of later age. The gneiss
penetrates the overlying schist and has often broken off slices
which have been floated away by the molten flood.

As mapped by Lawson, Couchiching schists are widely distrib-
uted on Rainy Lake, which must be looked on as the type locality.
In my field work many outcrops of these rocks have been studied
near Rice Bay, Grassy Portage, Gash Point, Goose Island, Sand
Point Island, and at other places on the way eastward toward
Bear’s Passage; and I can confirm Lawson’s description of them.

Near Grassy Portage and Nickel Lake they include iron range
rocks of a somewhat unusual variety, in which pyrite and pyr-
rhotite largely replace iron oxides; and some.miles to the west
on Rainy River, below Fort Frances, they are found with sand-
stone-like silica almost free from iron.

In general, however, the Couchiching schists occur in large
areas by themselves, always dipping at high angles (60°to 80°),
often having widths across the strike of hundreds of yards, some-
times of a mile or more. They may have various relations to the
green Keewatin schists, sometimes underlying them and at others
appearing to be interbedded with them. Near Shoal Lake there
are, however, schists resembling the Couchiching which lie above
the basal Huronian conglomerate and are evidently of much later
age.

Lawson maps the Couchiching as extending from west to east
across almost the whole Rainy Lake sheet, a distance of more than
60 miles; and the Hunter’s Island and Seine River sheets, to the
southeast and east respectively, contain large areas also, as mapped
by Lawson, W. H. Smith, and McInnes. The whole length shown
is about go miles, and the breadth 24 miles.

Lawson estimates the thickness of the Couchiching at about
25,000 feet, but in such ancient rocks, now folded in mountain
structures, it is possible and perhaps probable that this thickness
is excessive. The real thickness may be repeated many times by
folding, but it can hardly be less than some thousands of feet.

ie) A. P. COLEMAN

COUCHICHING IN OTHER REGIONS

Schists of the Couchiching type are widely found in northern
Ontario. They occur at various points on Lake-of-the-Woods,
e.g., on the southern edge of the Grande Presqu’isle, and near
the Scramble mine east of Kenora, where they are accompanied
by a band of granular silica having the look of sandstone. They
are found also in large areas near Clearwater and Manitou Lakes,
north of Rainy Lake, and extend for miles along the railway east
of Dryden, here associated with the iron formation.

Mica schist or gneiss of the same kind, and also arkose and
slate, are found on Sandy and Minnitakie Lakes north of Wabi-
goon; so that areas of Couchiching occur for a distance of more
than too miles north of the Minnesota boundary.

Within the past year or two similar rocks have been described
by E. S. Moore from near Round Lake, north of Lake Nipigon,
and by the present writer from Black Sturgeon Lake to the south
of Lake Nipigon.t In 1908 A. L. Parsons gave an account of
schists like the Grenville gneisses on the Algoma boundary? and
in the following year gray schists of the same sort were observed
by myself north of Jackfish and along the shore of Long Lake.
The Couchiching here has a width of several miles across the
strike, with dips of 60° or 7o°. W. J. Wilson in a “Summary
Report on the Algoma and.Thunder Bay Districts’? describes
such gneisses containing garnet, cordierite, sillimanite, etc., as
occurring extensively, and compares them with the Couchiching
and also with the Grenville gneisses; and W. H. Collins gives an
account in the same report of rocks of the same kind southwest of
Long Lake, containing garnets and graphite. He mentions quart-
zite and arkose as occurring there also.4

There are sillimanite gneisses and arkose, as well as ordinary
and carbonaceous slate, in various places in the Michipicoten
region 150 miles southeast of Long Lake, but the known area of
these rocks is not very large.

Mica schist with staurolite has been found by M. B. Baker in
the Abitibi region more than 200 miles to the east, and he men-
* Bur. Mines (1909), 144 and 158. 3G.S.C., No. 980, 5 and 6.

2 Tbid. (1907), Tot. 4Ibid., No. 1081, 14.

CLIMATE AND PHYSICAL CONDITIONS OF KEEWATIN 11

tions also graphitic slate, rusty weathering dolomite, and a coarse
fragmental series accompanying typical iron range rocks. He
suggests that the fragmental rocks may imply a break in the Kee-
watin, and quotes Miller and Brock as favoring this view."

Morley E. Wilson briefly describes similar rocks from the
Temiscaming region to the south as follows: ‘“‘On the north shore
of Larder Lake there is a belt—nearly a mile wide—of interbanded
phyllites, slates, and graywackes, which parallels the lake shore
for several miles. These rocks have a nearly vertical attitude;
a uniform northeasterly strike; are in places graphitic; and locally
contain small quantities of iron ore formation.’”

From the citations given above it will be seen that sedimentary
rocks like the Couchiching or the Grenville series are widely spread
in the Keewatin of Ontario. They often cover large areas and in
many places equal or surpass the eruptives in extent. It is true
that there are large gaps where no ordinary Keewatin sediments
are known to exist, but doubtless many small areas remain undis-
covered because unlooked for. A few years ago no one could have
foretold that the iron formation would be found in almost every
Keewatin area in Ontario, but we now know that this is the case.

The Keewatin sediments can no longer be overlooked as neg-
ligible in any account of the Canadian Archaean. In reality
these sedimentary rocks are the true Keewatin, and the accom-
panying eruptives and ash rocks must be considered less impor-
tant, in a sense accidental, members of the series.

The Keewatin of the states near Lake Superior seems from the
published accounts to contain a much smaller proportion of sedi-
mentary materials than of volcanics; which no doubt accounts
for the prevalent opinion among American geologists that the Kee-
watin, or the older part of the basal complex, consists essentially
of eruptive rocks.

RELATIONS OF THE KEEWATIN TO THE GRENVILLE SERIES

Having shown that the Keewatin contains sedimentary rocks
of every kind, some of them having a wide extent and a great
thickness, it is natural to compare them with the ancient sedi-

t Bur. Mines (1909), 275-78. 2, Sum. Rep., Geol. Sur. (1909), 175.

2 A. P. COLEMAN

mentary rocks of the Grenville and Hastings series of southern
and eastern Ontario and Quebec. ‘These were studied long ago
and were originally included in the Laurentian; though now the
term Laurentian is confined to the eruptive granites and gneisses
which penetrate them and rise from beneath them.

The nearest Grenville rocks to the Keewatin sediments described
above begin about 150 miles south of the Larder Lake region in
the township of Loring, just south of Lake Nipissing, where gra-
phitic schist occurs. Between this and Parry Sound crystalline
limestone and gray garnetiferous schists and gneisses are widely
found and were compared by myself in 1900 with the western
Couchiching.t There are also green schists in the region suggest-
ing western Keewatin schist of eruptive origin.

In eastern Ontario the Grenville and Hastings series often
greatly resemble the Keewatin, including banded silica and iron
ore, slate, quartzite, and fine-grained gray sedimentary gneiss con-
taining graphite. There are, however, some marked differences.
Limestones are rare in the western Keewatin but make the most
prominent rock in the Grenville and Hastings series, even reaching
a thickness of more than 50,000 feet, according to Adams; while
volcanic rocks play a larger part in the west than in the east. Just
how the eastern Archaean is related to the western is still a matter
of discussion, Adams thinking that the Grenville and Hastings
series are both probably the equivalent of the western Huronian,
while Miller believes that the Hastings series represents the Huro-
nian, and the Grenville series the Keewatin.

From my own observations it may be said that a considerable
part of the Grenville rocks are closely like the western Keewatin.
If they were found in the Upper Lakes region they would certainly
be classed on lithological grounds as Keewatin; and the two series
of rocks are also related in the same way to the Laurentian batho-
liths. In the east as well as in the west these great eruptive masses
are later than the overlying rocks and have pushed up through
them, often nipping them in as synclines. In neither case has the
foundation on which these earliest sediments were laid down been
preserved.

t Bur. Mines (1900), 169; also 182.

CLIMATE AND PHYSICAL CONDITIONS OF KEEWATIN 13

CONCLUSIONS

It has been shown in the foregoing pages that the oldest known
rocks in Canada, the Keewatin in the west, and the Grenville and
Hastings series in the east, stretching for 900 or 1,000 miles across
the country, include large amounts of sedimentary materials.
Among these rocks are limestones and dolomites, slate of ordinary
kinds and also slate charged with carbon, mica schist, and gneiss
having the composition of clayey sandstones, arkoses with angular
bits of quartz and feldspar, and in a few places also coarser frag-
mental rocks. In the east the seas were clearer and deeper, so
that limestone predominated. In the west volcanic activity was
very pronounced and lava streams, lapilli, and ashes occur on a
large scale, either mixed with the water-formed sediments or making
up thousands of feet of rock in themselves.

There must have been great land surfaces from which rivers
flowéd, bringing down sand and clay. Much of the material sug-.
gests well-weathered products derived from granite and gneiss;
but the arkoses, which are widespread and thick, probably imply
a cool and moist land surface. The sea contained plants to fur-
nish the carbon, often reaching several per cent in slates, gneisses,
and limestone; and the limestones hint at calcareous algae or
animals having hard parts.

All varieties of geological work seem to have been under way
in pre-Huronian times as they have been ever since; and there is
no evidence of special primeval conditions different from those
known to later geology.

In this paper the earliest Canadian sediments have been dis-
cussed from the point of view of climate and physical conditions,
and no attempts have been made to marshal the evidence from
other lands; but the Canadian Keewatin and Grenville are probably
~as old as any known rocks, and the same conclusions have been
reached from a study of the Archaean rocks of Europe and other
continents. Similar sediments penetrated by granites and gneisses
occur in the Lewisian of Scotland and the Ladogian of Finland
and other parts of Scandinavia. Last summer in Sweden I had
the opportunity to study Archaean sediments exactly like our
Keewatin, so that the conclusion reached in this paper may be

14 A. P. COLEMAN

extended to cover the most ancient formations of the Old World
also.

Though the Keewatin and Grenville series are the oldest known
formations in America, it is evident that they do not take us back
to the commencement of geological time, since they include
clastic sediments that imply the weathering and erosion of pre-
vious rocks before they were spread out on the sea bottom. We
have extended our outlook much farther into the past, but there
is still an impenetrable background beyond. We shall perhaps
never be able to say “‘‘in the beginning’; but we may safely say
that there is no hint of a molten earth in process of cooling down.
If the earth was ever hot it had so far cooled down before the
oldest known rocks were formed as to allow air and water and life
to do their work in the world very much as they do now. If the
earth ever passed through a period of great heat it was at a time
too remote in the past to leave a geological record or to have any
special interest for the geologist.

THE AGENCY OF MANGANESE IN THE SUPERFICIAL
ALTERATION AND SECONDARY -ENRICHMENT
OF GOLD DEPOSITS:

WILLIAM H. EMMONS

I. INTRODUCTION AND SUMMARY

Ferric iron, cupric copper, and manganitic manganese are
present in many mineral waters, and under certain conditions
any one of them will liberate chlorine from sodium chloride in
acid solutions. Nascent chlorine dissolves gold. Each of these
compounds releases chlorine at high temperatures, or in concen-
trated solutions. In cold, dilute acid chloride solutions, ferric
iron will not give nascent chlorine in appreciable quantity in 34
days, and cupric copper is probably even less efficient; but man-
ganitic compounds liberate chlorine very readily. In a cold solu-
tion containing only 1,418 parts of chlorine per million, consider-
able gold is dissolved in 14 days when manganese is present. It
should be expected, then, that those auriferous deposits, the
gangues of which contain manganese, would show the effects of
the solution and migration of gold more clearly than non-man-
ganiferous ores.

Gold thus dissolved is quickly precipitated by ferrous sulphate.
It is, therefore, natural to suppose that gold in such solutions
could not migrate far through rocks containing pyrite, since it
would be precipitated by the ferrous sulphate produced through
the action of oxidizing waters, or the gold solution itself, upon the
pyrite. But the dioxide and higher oxides of manganese react
immediately upon ferrous sulphate, converting it to ferric sulphate,
which is not a precipitant of gold. Consequently, manganese
is not only favorable to the solution of gold in cold, dilute mineral

t Published, in a more amplified form, by permission of the Director of the U.S.
Geological Survey in Bull. 46, American Institute of Mining Engineers, 768-837,
October, 1910.

16 WILLIAM H. EMMONS

waters, but it also inhibits the precipitating action of ferrous salts,
and thus permits the gold to travel farther before final deposition.

These statements apply to the action of surface waters descend-
ing through the upper parts of an auriferous ore deposit, since such
waters are cold, dilute, acid (i.e., oxidizing) solutions. In deeper
zones, where they attack other minerals, they lose acidity, until
the manganese compounds, stable under oxidizing conditions, are
precipitated together with the gold. Thus, manganite, as well as
limonite and kaolin, is frequently found in secondary (i.e., dis-
solved and reprecipitated) gold ores. Moreover, in the precipi-
tation of secondary copper and silver sulphides, ferrous sulphate
is generally formed; and, consequently, the secondary silver or
copper sulphides frequently contain gold.

Those deposits in the United States in which a secondary
enrichment in gold is believed to have taken place are, almost
without exception, manganiferous. Since secondary enrichment
is produced by the downward migration, instead of the superficial
removal and accumulation, of the gold, it should follow that both
gold placers and outcrops rich in gold would be found more exten-
sively in connection with non-manganiferous deposits; and this
inference is believed to be confirmed by field-observations.

Among the papers which treat the superficial alteration and
secondary enrichment of copper, gold, and silver deposits are
those of S. F. Emmons,’ Weed,? Penrose,? Winchell,4 Van Hise,5
Kemp,° and Rickard.? The processes upon which the changes
depend are clearly outlined in these, and subsequent work has,
in a large measure, confirmed the premises stated. The chemical

« “The Secondary Enrichment of Ore-Deposits,” Trans., XXX, 177-217 (1900).

2 “The Enrichment-of Gold and Silver Veins,” Trans., XXX, 424-48 (1900).

3“The Superficial Alteration of Ore-Deposits,’ Journal of Geology, II, No. 3,
288-317 (Apr.-May, 1904).

4 Bulletin of the Geological Society of America, XIV, 269-76 (1902).

5“*Some Principles Controlling the Deposition of Ores,’ Trans., XXX, 27-177
(1900).

6 “Secondary Enrichment in Ore-Deposits of Copper,’’ Economic Geology, I, No. 1,
11-25 (Oct.-Nov., 1905).

7“The Formation of Bonanzas in the Upper Portions of Gold-Veins,” Trans.,
XXXI, 198-220 (1901).

MANGANESE IN GOLD DEPOSITS 07

laws and physical conditions controlling secondary enrichment have
been reviewed in several reports more recently published. The
papers of Lindgren, Ransome, Spencer, Boutwell, Irving, Graton,
McCaskey, Spurr, and Garrey and Ball are particularly valuable.
Such work has shown that the secondary enrichment of pyritic
copper deposits is a very inportant process; that many silver
deposits are enriched by superficial agencies; but that many gold
deposits do not show deep-seated secondary enrichment.

T. A. Rickard’ has brought out clearly the processes by which
gold deposits may be enriched relatively near the surface in the
oxidized zone by the removal of valueless minerals which are more
readily dissolved than gold. On the problem of deeper-seated
precipitation of gold below the zone of oxidation there is less evi-
dence. In some mines, however, the transportation and deep-
seated precipitation of gold is clearly shown, as was pointed out
long ago by Weed.

While engaged in the investigation of certain auriferous deposits
in the Philipsburg quadrangle, Montana, for the U.S. Geological
Survey, I was confronted by evidence gained in two important
mines, which seemed to be conflicting on this point. In one of
them, the Cable mine, there was no evidence that gold had been
concentrated by cold solutions below the zone of oxidation, but in
the Granite-Bimetallic Lode there was enrichment of both gold and
silver below the zone of leached oxides.

Although the ores of the two deposits differ in other respects,
the most striking difference is in the manganese content. The
use of manganese in the chlorination process to give free chlorine,
which dissolves gold, is well known. Le Conte? said as early as |
1879 that free chlorine is the most important natural solvent of
-gold, and Pearce, in 1885, recorded experiments in which gold
had been dissolved in hot sulphate solutions with common salt
and manganese dioxide. Don obtained similar results with more
dilute solutions. It appeared desirable, therefore, to ascertain
whether these reactions are carried on in cold dilute solutions

1 Op. cit. 2 Elements of Geology, p. 285.

3 Proceedings of the Colorado Scientific Society, I, 3 (1885-87).

4 Trans., XXVII, 654 (1807).

18 WILLIAM H. EMMONS

similar to mine waters; and Nicholas Sankowsky and Clarence
Russell, in a seminar on the Chemistry of Ore Deposits, which I
conducted at the University of Chicago, compiled all available
analyses of waters from gold and silver mines in non-calcareous
rocks. A. D. Brokaw conducted a series of experiments, using cold
dilute solutions of compositions suggested by the analyses. He
performed other experiments applicable to the study of the pre-
cipitation of gold, showing the action of manganese dioxide on
ferrous salts. During the progress of this investigation, W. J.
McCaughey published his valuable paper on the solvent effect
of ferric and cupric salt solutions upon gold," and this in a large
measure supplemented the work carried on in the seminars at the
University of Chicago.

The experiments conducted by Brokaw showed that man-
ganese in the presence of chlorides and sulphates is very much
more efficient in the reactions dissolving gold than are the other
salts common in mine waters. To verify these results by field-
evidence, the review of the literature was taken up in greater detail,
and there also the results indicate a marked difference in the
behavior of the cold dilute mineral waters in the presence and in
the absence of manganese.

Lindgren’s classification of the gold deposits of North America
has been of great value in reviewing these deposits; since in the
United States manganese is rarely a gangue mineral in the primary
gold deposits as old as the early Cretaceous California gold veins,
whereas it is frequently present in appreciable quantities in those
deposits which were formed nearer the surface and which are
related to intrusives of Tertiary age.? I have not attempted to
review exhaustively the evidence afforded by deposits outside of
the United States with respect to the hypothesis suggested, but
some of these deposits appear to supply accurate confirmatory
data.

In a statistical study of outcrops, to ascertain whether gold
is more extensively leached in manganiferous lodes than in the

* Journal of the American Chemical Society, XX XI, No. 12, 1261-70.

2 W. Lindgren, ‘‘The Relation of Ore-Deposition to Physical Conditions,” Eco-
nomic Geology, I, No. 2, 105-27 (Mar.-Apr., 1907).

MANGANESE IN GOLD DEPOSITS 19

outcrops of those which do not carry manganese, and whether
placers are more frequently developed in connection with non-
manganiferous lodes, the reports of Dr. R. W. Raymond' have been
of great value.

I wish to acknowledge my indebtedness to my colleagues of
the U.S. Geological Survey, and to many other geologists whose
accurate observations I have drawn upon to test the hypothesis.
Their conclusions respecting the secondary enrichment of gold
appear to support the hypothesis, and, differing as they do with
respect to the migration of gold in particular deposits, they become
reconciled when inspected from this viewpoint, and thus they
are themselves supported. Dr. R. C. Wells has read critically
certain portions of this paper, where the principles of physical
chemistry are involved.

II. SALTS CONTAINED IN THE WATERS OF GOLD AND SILVER MINES
; IN NON-CALCAREOUS ROCKS

Sankowsky and Russell, utilizing all data available to them,
recalculated the analyses to the ionic form of statement, and made
the general average given in Table I.

Sulphates.—Primary gold ores generally carry pyrite, which,
oxidizing at or near the surface, yields ferrous sulphate, ferric
sulphate, and sulphuric acid. The acid is not formed directly
from galena, PbS, or from zinc-blende, ZnS; but pyrite, Fes.,
carries more sulphur than is required to supply SO, to satisfy the
iron, even if ferric sulphate, Fe.(SO,);, is formed instead of FeSQ,.
As shown by Buehler and Gottschalk, galena and zinc-blende dis-
solve much more slowly in the absence of FeS,. The reaction
probably requires free acid, which the iron sulphide, owing. to its
excess of sulphur, supplies. The sulphuric acid from pyrite is
increased also by the hydrolization of ferric sulphate, and the
deposition of limonite.

In Table I the sulphate radical is nearly ten times as great as
all other negative ions and is also in excess of bases, so that on any
basis of adjustment to form salts much H,SO, remains. The
table shows also an average of 97.26 parts per million of hydrogen,
indicating the strongly acid character of the solutions.

t Mines and Mining West of the Rocky Mountains (1868-75).

20 WILLIAM H. EMMONS

Chlorides.—Chlorine is present in most mine waters. In 22
out of the 29 analyses it is reported as traces or as determined
quantities. The average of 29 analyses shows 873 parts per
million, but if the one abnormally rich sodium-chloride water of
Silver Islet, Lake Superior, is excluded, the remaining 28 analyses
show but 111 parts per million. This figure is probably a better
average. There are several sources of the chlorine in mine waters.

TABLE I

AVERAGE OF 29 ANALYSES OF WATERS TAKEN FROM GOLD, SILVER, AND GOLD-
SILVER MINES IN Non-CALcAREOUS ROCKS

(Compiled by N. Sankowsky and C. Russell)

Parts per Million ae ee
Clee 24 Ate 873.10 22
SOR ee aieenne PAO 6) 13
COs EM, 77.50 7
NO,¢4 0.00 I
1210)n8 0.00 traces in 2
SHO}: 34.94 12
Ie ee ean 17 al
Na2 261.20 9
d Biter ays cid als 0.10 I
Ca. 295.00 II
Shc Sane 0.06 I
Migs: ee aes 242.44 9
ad eRe ics anit 333105 6
IN gage ol dio oles 30.91 6
ING one trace traces in 3
Cormeen es aa trace traces in 3
Cue ae eee 5.09 2
PA OE CD cee ntie ANA 2.70 5
Bett iim aye 2700) 22
Bele are negra 603.07 25
H (in acids)... 97.206 sme)

The salt in sedimentary rocks may be dissolved by ground-water.
From the available analyses it appears that this source is of less
importance than would be supposed. The chlorine content of
composite samples of 78 shales and of 253 sandstones was only a
trace, while an analysis of a composite of 345 limestones showed
only 0.02 per cent.t In some rocks chlorine is present probably
as NaCl in the solid particles contained in fluid inclusions. The
work of R. T. Chamberlin, A. Gautier, and others has shown that
many granular igneous rocks, when heated to high temperatures,

1F. W. Clarke, Bulletin No. 330, U.S. Geological Survey, 27(1908).

MANGANESE IN GOLD DEPOSITS 21

give off gases equal to several times their own volume. While
further inquiry of this character is desirable, it is probably true
that in general but little chlorine is present in such gases. But
gases from certain volcanic rocks, such as obsidian, often contain
a high proportion of chlorine and chlorides. Albert Brunt has
shown that some of the Krakatoa lavas yield gases which equal
about one-half the volume of the rock, and that more than half
of such gases consist of chlorine, hydrochloric acid, and sulphur
monochloride. The average chlorine content of igneous rocks
is, according to F. W. Clarke, 0.07 per cent.

Chlorine is present in nearly all natural waters. Its chief
source is from finely divided salt or salt water from the sea and
from other bodies of salt water. The salt is carried by the wind
and precipitated with rain.2, The amount of chlorine in natural
ponded waters varies with remarkable constancy with the distance
from the shore. The isochlores parallel the shore line with great
regularity, as shown by the map in Jackson’s report. The chlorine
contributed from this source even near the seashore appears small;
but it may be further concentrated in the solutions by evaporation
or by reactions with silver, lead, etc., forming chlorides, which
in the superficial zone may subsequently be changed to other com-
pounds. Penrose,? discussing the distribution of the chloride ores,
pointed out long ago that they form most abundantly in undrained
areas.

Carbonates and alkaline earths.—-The analyses in Table I do
not include those from mines in limestones. The carbonate
reported gives an average of 77 parts per million. Even in igneous
rocks considerable calcium (295 parts per million) and magnesium
(242 parts) are carried by the waters. They are derived in part
from reactions between the acid sulphates and the silicates of the
wall-rock.

™“Quelques recherches sur le volcanisme aux volcans de Java. Cinquiéme

partie. Le Krakatau,” Archives des sciences physiques et naturelles, Genéve, XXVIII,
No. 7 (juillet, 1909).

2D. D. Jackson, “‘The Normal Distribution of Chlorine in the Natural Waters
of New York and New England,” Water Supply and Irrigation Paper No. 144, U.S.
Geological Survey (1905).

sJournal of Geology, II, No. 3, 314 (April-May, 1894).

22 WILLIAM H. EMMONS

Alumina.—In some waters aluminum sulphate is abundant
(the average of aluminum, 333 parts per million). It forms where
sulphate waters attack kaolin, setting free SiO, and taking alumina
into solution.

Nitrates.—Nitrates are not abundant in mine waters. In one
analysis only’ is NO, reported (1.60 parts per million), and this
in a deep-seated water of questionable genesis.

Phosphates.—Traces only of PO, are reported from two mine
waters; others contained none, if determinations were made.

Silica.—Silica (35 parts per million) appears high for acid
waters. The analyses include a manganiferous sulphate water
from the Comstock, abnormally high in silica.?

Tron.—lIron is the most abundant metal in the waters of gold
mines. Ferric iron (603 parts per million) is, according to these
analyses, more than twice as abundant as ferrous iron (277 parts
per million). Ferrous iron is much more abundant below than
above the water-table.

Manganese —lIf manganiferous minerals are present in the
primary ore, they oxidize in the upper portion of the deposit to
manganese dioxide or other high oxides of manganese; and these,
in turn, oxidize ferrous sulphate, in the presence of sulphuric acid,
to ferric sulphate.

Copper.—One analysis shows 147 parts of copper per million.
Two other analyses show traces. Small amounts must be present
in many other waters, since gold ores often carry copper. Pos-
sibly, small traces of the heavy metals were not looked for in many
of the waters analyzed.

Ill. CHEMICAL EXPERIMENTS IN THE SOLUTION AND DEPOSITION
OF GOLD

The migration of gold in the deposits takes place at low tem-
peratures. At the surface the temperatures range between o°
and 50° C. and pressures do not exceed one atmosphere. With
the normal gradient of increase, the temperatures, even several

t Geyser Mine, Silver Cliff, Colo. See S. F. Emmons, Seventeenth Annual Report,
U.S. Geological Survey, Part II, 462 (1895-06).

2 Bulletin of the Department of Geology, University of California, IV, No. 10, 192
(1904-6).

MANGANESE IN GOLD DEPOSITS 23

thousand feet below water level, would not exceed 100° C., and in
the main are considerably lower. The general character and,
approximately, the concentration of the solutions are known and
the conditions are fairly constant. From the mass of chemical
data relating to the subject, the following experiments are par-
ticularly suggestive in connection with the present problem.

1. Stokes* placed gold leaf in a solution containing 25 gm.
per liter of ferric sulphate, and, after heating to 200° C., found
that not a trace of gold had been deposited in the cold part of the
sealed tube in which the experiment was carried on. This experi-
ment does not confirm:the statement frequently made that ferric
sulphate will dissolve gold.

2. Don? exposed to air, gold and auriferous sulphide ores in
solutions containing from 1 to 20 gm. of ferric chloride and ferric
sulphate per liter of water; after several months no gold had been
dissolved.

3. W. J. McCaughey,? upon boiling for several hours 50 c.c.
of HCl (sp. gr. 1.178) diluted to 125 c.c. with 250 mg. of gold,
found there was no loss of gold.

4. In a bent tube Stokes? heated gold leaf for 16 hours at 200°
C. in a solution composed of 85 gm. of cupric chloride and 133
c.c. of 20 per cent HCl in a liter of water. The gold leaf was dis-
solved and redeposited in the upper portion of the tube. He writes
the reaction as follows:

Au -eCucls Aue -3Cuch

5. Stokes’ heated gold leaf to 200° C. in a closed tube con-
taining a solution of 25 gm. of ferric sulphate and o.o1 gm. of
NaCl. Gold was dissolved in 40 hours.

6. Stokes® found that at 200° C. gold leaf was dissolved in a
mixture of 2 parts of 20 per cent solution of ferric chloride and 1
part of 20 per cent solution of HCl.

t Economic Geology, I, No. 7, 650 (July-Aug., 19060).

2 Trans., XXVII, 598-(1897).

3 Journal of the American Chemical Society, XX XI, No. 12, 1263 (Dec., 1909).

4Op. cit., I, 640.

5 Economic Geology, I, No. 7, 650 (July-Aug., 1906).

6 Ibid., 650.

24 WILLIAM H. EMMONS

7. W. J. McCaughey? dissolved gold at from 38° to 43° C.,
in hydrochloric acid solutions of ferric sulphate. The results
are indicated by the curves in Fig. r. Solution A contained 1 gm.
of iron, introduced as ferric sulphate, and 25 c.c. of HCl (sp. gr.
1.178) in a solution diluted to 125 c.c. containing 250 mg. of gold
rolled to 0.009 inch. Solution B contained the same amount of
iron sulphate and 50 c.c. of HCl. Solution C contained 2 gm. of
Fe as ferric sulphate and 25 c.c. of HCl. Solution D had twice

MILLIGRAMS OF GOLD
DISSOLVED

0 20 40 60 80 100 120 140 160 180
TIME, HOURS

Fic. 1.—Diagram Showing the Rate of Solution of Gold in Concentrated Solutions
of Hydrochloric Acid and Ferric Sulphate. (Illustrating Experiment 7, by
McCaughey.)

the concentration of A. The diagram shows the amount of gold
dissolved after different periods of treatment.

8. McCaughey? found that gold is dissolved at from 38° to
43° C. in a strong solution of cupric chloride and HCl. The
amounts dissolved are shown by the curves in Fig. 2. Solution
A contained 1 gm. of Cu as cupric chloride and 25 c.c. of HCl
(sp. gr. 1.178); solution B, 1 gm. of Cu as CuCl, and 50 c.c. of
HCl; solution C, 2 gm. of Cu as CuCl, and 25 c.c. of HCl; and
solution D, 2 gm. of Cu as CuCl, and 50 c.c. of HCl; the final
solution being in all cases diluted to the volume of 125 c.c. The

Journal of the American Chemical Society, XXXI, No. 12, 1263 (Dec., 1909).
2 Tbid., 1264.

MANGANESE IN GOLD DEPOSITS 25

diagram shows that D, which was twice as concentrated as A, dis-
solved about 12 times as much gold.

g. Richard Pearce’ placed native gold in a flask containing
hydrated manganese dioxide with 4o gm. of salt and 5 or 6 drops
of H.SO,. After heating for 12 hours appreciable gold had been
dissolved.

to. T. A. Rickard’ extracted 99.9 per cent of the gold from
manganiferous ore with a solution of ferric sulphate, common salt,
and a little H,SO,.

11. Don’ found that 1 part of HCl in 1,250 parts of H,O, in
the presence of MnO., dissolves appreciable gold.

MILLIGRAMS OF GOLD
DISSOLVED,

sue} =
eats C
jz Ze ee Se ee 1 <A
0 20 40 60 80 « 100 120 140 160 180
TIME, HOURS

Fic. 2.—Diagram Showing the Solubility of Gold in Concentrated Solutions of Hydro-
chloric Acid and Cupric Chloride. (Illustrating Experiment 8, by McCaughey.)

A number of experiments on the solubility of gold in cold dilute
solutions were made by A. D. Brokaw.4 The nature of these
experiments is shown by the following statements, in which (a)
and (6) represent duplicate tests:

12. Fe,(SO,);,+H.SO,+Au.
(a) no weighable loss. (34 days.)
(b) no weighable loss.
13. Fe.(SO,),+H.SO,+MnO,--Au.
_ (a) no weighable loss. (34 days.)
(b) 0.00017 gm. loss.5

! Trans., XXII, 739 (1893).

2 Trans., XXVI, 978 (1806). 3 Trans., XXVII, 599 (1897).

4 Journal of Geology, XVIII, No. 4, 321-26 (May-June, 1910).

5 This duplicate was found to contain a trace of Cl, which probably accounts for
the loss.

26 WILLIAM H. EMMONS

i. HeCL- HCl Au.

(a) no weighable loss. (34 days.)
(b) no weighable loss.

15. FeCl,+HCI+Mn0O,+Au.

(a) 0.01640 gm. loss. Area of plate, 383 sq.mm. (34
days.)
(b) 0.01502 gm. loss. Area of plate, 348 sq. mm.

In each experiment the volume of the solution was 50 c.c.
The solution was one-tenth normal with respect to ferric salt and
to acid. In experiments 13 and 15, 1 gm. of powdered manganese
dioxide was also added. The gold, assaying ggg fine, was rolled
to a thickness of about 0.002 inch, cut into pieces of about 350 sq.
mm. area; and one piece, weighing about 0.15 gm., was used in
each duplicate.

To approximate natural waters more closely, a solution was
made one-tenth normal as to ferric sulphate and sulphuric acid,
and one twenty-fifth normal as to sodium chloride. Then 1 gm.
of powdered manganese dioxide was added to 50 c.c. of the solution,
and the experiment was repeated. The time was 14 days.

16a. Fe,(SO,);+H.SO,+NaCl+Au.

No weighable loss.
16). Fe,(SO,);-++H.SO,+NaCl+MnO,+Au.
Loss of gold, 0.00505 gm.

The loss is comparable to that found in experiment 15, allow-
ing for the shorter time and the greater dilution of the chloride.

To determine whether the free acid or the ferric chloride is
the solvent, experiment 17 was made, in which 50 c.c. of one-tenth
normal HCl was used with 1 gm. of powdered MnO,.

17. HCI+MnO,-+-Au.

Loss of Au, 0.01369 gm. ‘Time, 14 days.

In experiment 18, sodium hydroxide was added to 50 c.c. of
one-tenth normal ferric chloride solution until the precipitate
formed barely redissolved on shaking, after which 1 gm. of pow-
dered MnO, was added.

18. FeCl,+MnO,-+Au.

Loss of Au, 0.00062 gm. ‘Time, 14 days.

MANGANESE IN GOLD DEPOSITS 2G

These results show that, in the presence of manganese dioxide,
free hydrochloric acid is more efficient than ferric chloride. The
same amount of chlorine was present in both solutions.*

2.0

1.6

=
_

i
°
re)

MILLIGRAMS OF GOLD DISSOLVED
ro)

=
o

0.04 0.08 0.12 0.16 0.20 0.25
GRAMS Fe AS FERROUS SALT IN 125 cc.

Fic. 3.—Diagram Illustrating the Effect of Ferrous Sulphate in Suppressing the
Solubility of Gold in Ferric Sulphate Solutions, where Gold is Dissolved as
Chloride. (Illustrating Experiment 10.)

19. McCaughey’s experiments show the effect of very small
amounts of ferrous sulphate on solutions of gold in ferric sulphate.
To a solution, 125 c.c., containing 1 gm. of iron as ferric sulphate
and 25 c.c. of HCl, ferrous sulphate was added in quantities con-
taining from o.or to 0.25 gm. of ferrous iron. The solutions were
immersed in boiling water and subsequently 250 mg. of gold was

t Brokaw, Journal of Geology, XVIII, No. 4, 322-23 (May-June, IgI0).

28 WILLIAM H. EMMONS

added. The dissolved gold was determined at the end of 1 hour
and 3 hours. At the end of 3 hours the gold dissolved was
greater, probably because some ferrous sulphate had changed to
ferric sulphate. Even o.o1 gm. of the ferrous iron greatly decreases
the solubility of gold in the ferric sulphate and HCl solution, and
0.25 gm. of ferrous sulphate drives nearly all the gold out of solu-
tion. These experiments are illustrated by Fig. 3. The lower
curve represents conditions at the end of 1 hour, the upper curve
at the end of 3 hours, when some of the ferrous salt had oxidized
by contact with the air.

20. To determine the rate at which ferrous sulphate, in the
presence of sulphuric acid and manganese dioxide, would be oxi-
dized to the ferric salt, Brokaw made the following experiment:

One hundred c.c. of 1.6 normal FeSO was acidified with sulphuric
acid and shaken vigorously with 5 gm. of powdered MnO,. After
5 minutes the solution was filtered. No ferrous iron was detected
by the ferricyanide test, showing that the iron had been com-
pletely oxidized to the ferric state.

IV. DISCUSSION OF EXPERIMENTS

Nitrates.—Dilute acid nitrate-chloride waters readily dissolve
gold, since they are equivalent to weak aqua regia. The chlorine
set free by the reaction oxidizing HCl is more active than a solu-
tion of chlorine in water, and converts gold into gold chloride.

In the reaction by which gold is dissolved in chloride solution
its solvent power may be ascribed to its ‘“‘nascent’’ state. In
such reactions the presence of an element with more than one
valence is a necessary condition and its valence is reduced as gold
passes into solution.

The reaction of 3HCI+HNO,, giving nascent chlorine, may be
written as follows:

f
cl- Hee 0= | N = 02H |G oH Cl-ECl=N=0,.

_ When nascent chlorine reacts with gold, it forms soluble gold
chloride.

t Alexander Smith, General Inorganic Chemistry, 449 (1907).

MANGANESE IN GOLD DEPOSITS 20

In the 29 analyses of mine waters NO, is reported from but
one. Possibly nitrates are more abundant than is indicated by
the analyses; and if so, they must increase the solvent power of
chloride solutions; but the data at present available do not indi-
cate that they affect the superficial reactions to any important
extent.

Manganese oxides.—That gold is dissolved in moderately dilute
solutions containing salt and manganese oxides is shown by exper-
ments 11, 15, and 16. The reaction with manganese used to
prepare chlorine commercially is illustrated by the following
equation. (The reaction is not so simple as stated. It is discussed
later.)

Mn"*0,-++ 2NaCl-++3H,SO,— 2H,0+ 2NaHSO,+ Mn#SO,-+-2Cl.

At the beginning of the reaction the manganese has a valence of
four; at the end a valence of two. With acid the reaction may be
as follows:

MnO,+4HC!— 2H,O+ MnCl+ Cl.

Besides the presence of a chloride, some other conditions are
essential to the solution of gold. There appear to be two. One
is that some other substance must also be present which is capable
of being reduced so as to liberate chlorine—as, for example, a ferric
salt which may be reduced to the ferrous, a cupric to the cuprous,
the higher manganese salts to the lower, etc. The other is the
evolution of “nascent” chlorine. ‘This is particularly illustrated
by the action of aqua regia or the production of chlorine by hydro-
chloric acid and pyrolusite. In short, any of a number of methods
of producing free chlorine would be effective in the solution of
gold. Possibly both of the conditions just mentioned may in the
last analysis be identical. The essential point is that the atomic
chlorine in a state of molecular exchange or evolution is able to
combine with the gold. For present purposes the gold may be
considered to dissolve as gold chloride, although chemical investi-
gations favor the theory that a complex ion containing gold is
formed. The only consideration which becomes important in its
geological aspect is the presence of the compounds which not only

30 WILLIAM H. EMMONS

admit of easy changes of valence, but which act upon hydrochloric
acid with the production of free chlorine.
In mine waters chlorine is supplied as NaCl.

16b. Fe,(SO,),+ H,SO,+ NaCl+ MnO,-+ Au.
N/to IN/ 107 UN) 25 em 0 orovemn,
0.00505 gm. loss of gold by solution in 14 days (cold).

Under the same conditions without manganese there was no
weighable loss (see experiment 16a).

As used herein the normal solution contains 1 gm.-equivalent
of the solute in 1 liter of solution. A solution normal with respect
to chlorine contains 1 gm. of chlorine times 35.45, the molecular
weight of chlorine, in 1 liter of solution.

In this experiment the concentration of Cl (1,418 parts per
million) is not so great as has been observed in a few mine waters,
and not more than three times as great as Don determined in
waters from a number of Australasian mines."

Manganese is abundant in many gold-bearing deposits; is
sparingly represented in some; and from a very large number it
has not been reported. The chief primary minerals are the car-
bonates (rhodochrosite and manganiferous calcite), the silicate
(rhodonite), amethystine quartz, and the less-abundant sulphide,
alabandite. Some rock-making minerals carry small amounts
of manganese. It readily forms sulphates, chlorides, etc., and is
dissolved by acid mine waters. Manganese changes its valence
more readily than other elements common in gold ores.

Lead oxides.—Lead oxide is said to facilitate the solution of
gold? when added to solutions of ferric sulphate and sodium chlo-
ride. Lead is both bivalent and quadrivalent and forms corre-
sponding oxides and hydroxides. These, however, are generally
not abundant in the oxidized zones of lead-bearing ore deposits,
because the lead carbonate and the sulphate are relatively insoluble
in water and usually are formed instead of the oxides. Lead is
reported in but one of the 29 analyses of waters from gold and

t Trans., XXVII, 654 (1897).

2 Victor Lehner, Journal of the American Chemical Society, XXVI, No. 5, 552
(May, 1904).

MANGANESE IN GOLD DEPOSITS 31

silver mines, tabulated above. It is believed to be of very sub-
ordinate importance in connection with the solution of gold.

The efficiency of ferric iron and cupric copper to supply nascent
chlorine, compared with that of manganitic manganese.—Solutions
of ferric sulphate with sulphuric acid and salt dissolve gold at high
temperatures. Concentrated solutions of ferric sulphate and
hydrochloric acid dissolve gold at from 38° to 43°C. In the cold
the reaction may go on in concentrated solutions, but in those
approximating the concentration of mine waters no weighable
loss of gold was obtained. With MnO, under the same conditions
there was a very appreciable loss in a solution containing only
1.4 gm. of Clin a liter. It appears, therefore, that the action of
ferric iron on gold in cold dilute mine waters with H,SO, and
NaCl is probably negligible; for the experiments with ferric iron
in such solutions, without manganese, extended over a period of
34 days without weighable loss of gold.

Many auriferous deposits contain copper, but since the reactions
which give nascent chlorine are conditioned upon the presence of
some element that changes its valence in the reactions, and since
the processes underground take place in sulphate solutions, it did
not appear necessary, after ferric salt had been shown to be incom-
petent, to conduct experiments with copper; for, as is well known,
cuprous salts have never been detected in acid sulphate mine
waters, whereas ferric and ferrous sulphate are very common in
such waters. It has been shown’ however that the efficiency of
cupric salt in cold solution compared with that of manganitic salt
probably lies somewhere between 0.004 and 0.000001.

Amount of chlorine necessary for the solution of gold with man-
ganese compounds present—In experiment 15 (a), with Mn0O.,
0.01640 gm. of gold was dissolved in 34 days with solution one-
tenth normal with respect to chlorine. A solution with but 4o
_ per cent as much Cl (experiment 160) dissolved 31 per cent as much
gold in 14 days as was dissolved in the more concentrated solution
in 34 days. These results show that in 15 (a) conditions are prob-
ably approaching equilibrium, and also that the solvent power of
chlorine is approximately proportional to the amount present.

t Bull. Amer. Inst. Mining Eng., 790 (October, 1910).

32 WILLIAM H. EMMONS

That a weighable quantity of gold is dissolved when only a trace
of chlorine is present is shown by experiment 13 (6), in which
chlorine was introduced without intention.

The precipitation of gold.—In igneous rocks ferrous sulphate is
the chief precipitating agent. Ferrous sulphate is formed by the
oxidation of pyrite, but in the presence of oxygen and H,SO, it
becomes ferric sulphate, which does not precipitate gold. Below
the water-table, where pyrite is more abundant and free oxygen
less abundant, ferrous sulphate may persist in the mine waters.
Ferrous sulphate is so effective as a precipitant of gold that it is
used for that purpose in metallurgical processes. Experiment 19
shows that a minute amount of ferrous sulphate greatly decreases
the solubility of gold, although it does not precipitate it com-
pletely. With excess of ferrous salt practically all of the gold is
precipitated.

Ferrous sulphate is formed in the upper part of a lode above
the water-table; but owing to the open condition of that part of
the lode, air is freely admitted and ferric sulphate forms, at the
expense of ferrous sulphate and sulphuric acid. ‘This reaction takes
place almost instantaneously if MnO, is present (experiment 20),
for ferrous sulphate and manganese dioxide are under these condi-
tions incompatible. Manganese dioxide then not only releases
the solvent for gold, but eliminates the salt which precipitates 1t.
It is doubtful whether appreciable amounts of gold are ever carried
far below the water-table in mines where the waters carry ferrous
sulphate, but, in the presence of MnO., ferrous sulphate may be
eliminated below the water-table.

When manganese dioxide takes part in the reactions by which,
under the conditions named, gold is dissolved, transported, and
precipitated, the manganese salt is itself changed. At the surface
pyrolusite, MnO,, forms, for there the excess of oxygen prevails;
and this mineral is commonly found in the gossan of manganiferous
lodes. When solutions containing H,5O, and NaCl react on MnO,
there is a tendency to form MnSO,, and some manganese goes into
solution as sulphate, but salts of manganese with higher valence
may also form. In this connection Dr. R. C. Wells has offered the
following statement:

MANGANESE IN GOLD DEPOSITS 33

In an acid solution containing some free chlorine, such as has been assumed
to be effective in dissolving gold, there would also be a tendency towards the
formation of permanganic acid. On the other hand, the production of the
chlorine necessarily results in the reduction of the manganese compound.
Now a manganous salt is known to react with permanganate to reproduce
Mn0O, and this illustrates the tendency of manganese to pass with ease from
one stage of oxidation to another. The precipitation of manganese will occur
more and more as the solution loses its acidity. It is well established that
manganous salts in an acid environment are very stable; but in neutral or
alkaline solutions they oxidize more vigorously, one stage of their oxidation
being the manganic salt which hydrolyzes into Mn.O, - H.O (manganite), with
even greater ease than ferric salts into limonite.

In these ways the migration of an acidic solution would result in the trans-

portation of both gold and manganese. But in a region of basic, alkaline, and
reducing environment the manganese would be reprecipitated, the free acid
neutralized, the chlorine absorbed by the bases and removed, and owing to
the accumulation of the ferrous or other reducing salts, the gold would be
reprecipitated.

V. THE TRANSFER OF GOLD IN COLD SOLUTIONS

1. Restatement of the processes as related to secondary enrichment.
—Every theory of secondary enrichment of the metals consists
essentially of three parts: (a) solution, (0) transportation, (c)
precipitation.

a) As already stated, there is in the upper part of the ore
deposit, where oxidation prevails, abundance of ferric sulphate
and sulphuric acid. A little salt, NaCl, or other chloride, is gen-
erally present. The H,SO,, reacting upon NaCl, gives HCl, which
in the presence of MnO, gives nascent chlorine, which dissolves
gold. Some manganese goes into solution as sulphate, but certain
higher manganates are possibly formed as well. .

b) This chemical system will move downward under hydro-
static head. If it comes into a zone containing pyrite it will react
upon the pyrite, and in the oxidation of the latter more iron sul-
phates and acid will be formed. If manganese dioxide is present,
or if permanganic acid has been formed, no gold will be precipi-
tated, and the system, with gold still in solution, will move to
greater depths before ferrous sulphate can become effective.

c) But as the system moves downward, where no new sources
of oxygen are available, the excess of acid is removed. There are

34 WILLIAM H. EMMONS

many ways by which acidity is reduced along with these reactions,
but the principal one is probably the kaolinization of sericite
and feldspar. In these reactions sodium, potassium, calcium,
magnesium, and other sulphates are formed from acid and silicates;
the silica remaining as SiO, and kaolin; the alkalies and alkalic
earth sulphates going into solution. As the acidity decreases,
iron and manganese compounds tend to hydrolyze and deposit
oxides. At this stage of oxidation FeSO, becomes increasingly
prominent, and not only completely inhibits further solution of
gold but becomes increasingly effective as a precipitant. Thus
manganite 1s probably precipitated with gold. The fractures in
the primary pyritic gold ore below the water level thus become
coated with a manganiferous gold ore, which may be very rich.
The excess of oxygen which the system has carried down is used
up in the manner indicated, and in this process limonite is formed,
consequently the manganiferous gold ore deposited in the fissures
and cracks contains kaolin and iron as well as manganese oxides.

2. The oscillating, descending, undulatory water-table.—The
terms ‘‘water-table” and ‘‘level of ground-water” are generally
used to describe the upper limit of the zone in which the openings
in rocks are filled with water. This upper limit of the zone of
saturation is not a plane, but a warped surface. It follows in
general the topography of the country, but is less accentuated.
It is not so deep below a valley as below a hill, but it rises with the
country toward the hilltop and in general is higher there than in
the valley. Nor is it stationary. In dry years it is deeper than
in wet years, and in dry seasons it is deeper than in wet seasons.
The difference of elevation between the top of this zone in a wet
year and in a dry year is normally greater under the hilltop than
on the slopes and in the valleys. In mines where the ground is
open the level of ground-water probably changes with every con-
siderable rain. Consequently, there is a zone above ground-water
in dry periods but below it in wet periods, and in hilly countries
this may be of considerable vertical extent. Thus the water-table
oscillates, though in general moving downward with degradation
of the land surface. It is in this zone of oscillation of the water-
table that chemical activity is most varied. Without any change

MANGANESE IN GOLD DEPOSITS 35

in the character of the drainage or of the more constant conditions
controlling the water-circulation, the chemical composition of the
solutions affecting this zone may change from season to season.
They may at one time be ferric sulphate or oxidizing waters, and
at another time ferrous sulphate or reducing waters, since, after
a wet season, the ferrous sulphate waters from below would tend
to rise, after dilution with fresh water added by the rains. Conse-
quently, the minerals of this zone may include, besides the residual
primary and secondary sulphides, the oxides, native metals, chlo-
rides, etc. Between the top of this zone and the surface or the
apex of the deposit chemical activity is probably slow, because
there is a scarcity of sulphides and other easily altered minerals
to supply the salts upon which the chemical activity of ground-
water in a large measure depends. As the country is eroded, this
zone also descends; and if a mineral or metal persists long enough,
the upper limit of the zone of active change passes below it, and
may ultimately be exposed at the outcrop.

3. The several successive zones in depth—As shown by S..F.
Emmons, W. H. Weed, and others, many lodes, when followed from
the surface down the dip, show characteristic changes. Below the
outcrop, the upper part of the oxidized portion of the lode may be
poor. Below this there may be rich oxidized ores; still farther
down, rich sulphide ores; and below the rich sulphides, ore of
relatively low grade. Such ore is commonly assumed to be the
primary ore, from which the various kinds of ore above have been
derived. The several types of ore have a rude zonal arrangement,
the so-called “zones” being, like the water-table, undulatory.
They are related broadly to the surface and to the hydrostatic
level, but are often much more irregular than either; for they
depend in large measure on the local fracturing in the lode which
controls the circulation of underground waters. Any zone may
be thick at one place and thin, or absent, at another. If these
zones are platted on a longitudinal vertical projection, it is seen
that the primary sulphide ore may project upward far into the
zone of secondary sulphides, or into the zone of enriched oxides,
or into the zone of leached oxides, or may even be exposed at the
surface. The zone of secondary sulphide enrichment (which is

26 WILLIAM H. EMMONS

not everywhere present) may project upward far into the zone of
rich oxidized ore, or into the zone of leached oxides, or may outcrop
at the surface. The zone of sulphide enrichment nearly always
contains considerable primary ore, and very often the secondary
ore is merely the primary ore containing in its fractures small
seams of rich minerals. The zone of enriched oxides is generally
found above the water-table when the latter is at the lowest, and
often extends to the outcrop. In regions of rapid erosion, and es-
pecially of rugged topography, the conditions for the exposure of rich
oxides, or even rich sulphides or primary ore, are more favorable.
In places along the outcrop of a deposit where erosion is rapid the
richer oxidized or sulphide ores may be exposed, whereas in other
places, protected from erosion, and therefore exposed longer to so-
lution, the same outcrop is frequently leached. It is evident that
the amount of metal remaining in the upper part of the oxidized
zone and at the outcrop depends upon the ratio between the rate
at which the metal is dissolved, and the rate at which the value-
less constituents are dissolved and removed. Under certain
conditions gold is removed very slowly, and the removal of value-
less constituents may effect a concentration at the very apex of
the lode; while under other conditions, favorable to the solution
of gold, it is removed more rapidly than silica, iron, etc., and the
apex and the oxidized zone are leached. In a country not subject
to erosion it would be supposed that the outcrops of manganifer-
ous lodes would be everywhere leached; but rapid erosion may
remove the upper part of the lode before it is completely leached,
and, under favorable conditions, placers accumulate from the débris-
of the apex.

It thus appears that all of these zones except that of the pri-
mary ore are continually descending; so that ore taken from the
outcrop may represent what was once primary ore; afterward, ©
enriched sulphide ore; still later, oxidized enriched sulphide ore;
later still, leached oxidized enriched sulphide ore; and finally
become the surface ore. Through more rapid erosion at some
particular part of the lode, any one of these zones may be exposed;
and hence an outcrop ore of any character is possible. Conse-
quently, longitudinal assay plans, showing the changes of value

MANGANESE IN GOLD DEPOSITS ay

in depth, though highly suggestive, and especially so when gold
and silver are shown separately, are supplemented by studies of the
paragenesis and by physiographic studies, in order that the approxi-
mate rate of erosion of the lode at various places may be known.
In the absence of such knowledge, it is generally impossible to
tell the genesis of a particular sample of ore from amine. When all
the data are assembled, however, greater confidence may be placed
in the conclusion, since all the factors in the problem are intimately
related.

4. Criteria for the recognition of secondary enrichment.—I shall
not attempt to review all the criteria for the recognition of second-
ary enrichment. They involve practically all available data relat-
ing to the geology and physiography of a region, as well as the
observed characteristics of its ore deposits. But each group of
deposits may be studied with certain general criteria in view.
Among these are: (1) the vertical distribution of the richer por-
tions of the lode with respect to the present surface and to the
level of ground-water; (2) the mineralogy of the richer and poorer
portions of the deposit, and the character and vertical distribution
of the component minerals; (3) the paragenesis, or the structural
relations shown by the earlier ore and that which has been intro-
duced subsequently.

In applying these principles, it should be remembered that
circulation is generally controlled by post-mineral fracturing;
that the changes depend upon climate and rapidity of erosion, and
are affected by regional changes of climate, etc. Although the
mineralogy of the ore is a useful aid, there are many minerals
which are precipitated from cold solution and also from ascend-
ing hot solutions, and there are many others, the genesis of which
is uncertain. Of the minerals formed in the zone of secondary
sulphide enrichment, few, if any, are known positively to form
under such conditions only. There are some, however, such as
chalcocite and covellite, which nearly everywhere are clearly of
secondary origin. Ruby silver is frequently, but not always,
secondary. Other minerals, such as chalcopyrite, bornite, argen-
tite, etc., have no definite indicative value unless their occurrence
suggests that they are later than the primary ore. Where minerals,

38 WILLIAM H. EMMONS

known to have formed elsewhere by processes of secondary sulphide
enrichment, are clearly later than primary ore, there is a strong
presumption that they were deposited by cold descending waters.
If it can be shown, in addition, that they do not extend to the
bottom of the mine, but are related to the present topography of
the country, then this presumption may be regarded with consid-
erable confidence as confirmed.

With respect to gold, the problem is difficult, because the
native metal is the only stable gold mineral known to be depos-
ited from cold dilute solutions. Consequently, the applicable
criteria are limited; and the vertical distribution of the richer
ore, though suggestive, is not in itself conclusive. Lindgren
and Ransome, in their studies at Cripple Creek, have shown that
the richer ore bodies may have in general a relationship to eleva-
tion, where there is little or no evidence of deep-seated secondary
enrichment. The maximum deposition by ascending hot waters
may be greater at one horizon than at another; and the rich ore,
though showing broadly certain variations with depth, is in no
way related to the water-table. If, however, it can be shown that
rich seams of ore cross the primary ore and do not extend down-
ward as far as the lowest level in the primary ore, but are related
to the present topography of the country, and if it is known that
the associated minerals which fill such openings are those which may
be deposited by cold waters, the evidence of their secondary
origin is practically conclusive. As already shown, seams of gold
with limonite and manganese oxides occur in such relations.
Similar ore frequently contains chalcocite and argentite also.
Such occurrences could with great confidence be attributed to
descending waters.

In the practical application of such reasoning to gold-bearing
deposits it will sometimes be necessary to discriminate between
the oxidized manganiferous gold ore which has resulted simply
from the oxidation of a primary manganiferous ore like one con-
taining rhodochrosite, and that which has been deposited in
fractures in the sulphides lower down. In other words, it is
desirable to know whether rich manganiferous ore in the upper
part of a mine is residual from a primary ore body, and there-

MANGANESE IN._ GOLD DEPOSITS 39

fore will probably prove extensive, or represents the result of
concentration under more deeply seated conditions after the
manner indicated above. This discrimination may be easy in
the sulphide zone, where the fractures with rich manganiferous
ore are clearly shown; but in the oxidized zone one must rely
upon the shape and distribution of the richer portions. If they
are related to cracks in the mass of the oxidized ore, the inference
is warranted, in the absence of other evidence, that they are
residual secondary ore, and, being genetically related to the present
topographic surface, are limited.

Native gold is, as already stated, the only gold mineral which
is deposited by cold solutions. But native gold is deposited by
primary processes also, and is by far the most abundant gold
mineral so deposited. Consequently, in distinguishing between
primary gold and gold deposited by cold solutions, one must rely
upon associated minerals. When secondary chalcocite or certain
secondary silver minerals are deposited, the attendant reactions
precipitate gold. Consequently, the richer bunches of gold ore in
the oxidized zone, residual from secondary ore formed under the
deeper-seated conditions, may carry also considerably more copper
and silver than the primary ore. But copper, and (unless cerargy-
rite is formed) silver also, are more readily leached than gold,
even when manganese is present. Hence, the evidence of this
character may have been destroyed.

With respect to other minerals associated with the secondary
gold ore, we are not warranted, in the present state of our knowl-
edge, in drawing definite conclusions. From the nature of the
reactions, I think it may be possible to show that manganite,
Mn,O,°H,O, is, under conditions of incomplete oxidation, more
often associated with the rich gold in such relations than pyrolusite,
MnO.; for, as already observed, the lower oxide is more likely
to be precipitated than the higher, when secondary gold is depos-
ited under deep-seated conditions. But under oxidizing influences
the manganese oxides change their character so readily that this
criterion, if it has any value, is probably not applicable to ores
in the upper part of the oxidized zone, where they have been
exposed to more highly oxygenated waters for a longer time. I

40 WILLIAM H. EMMONS

make these suggestions with respect to the character of the man-
ganese oxides associated with the rich ore, not because I think the
reactions which precipitate manganese are well enough understood
to give a positive paragenetic value to the oxidized manganese
minerals themselves, but in the hope that others will ascertain and
report the character of the manganese oxide associated with gold
in the deeper zone and in the residual products from that zone.

5. Lateral migration of manganese salts from the country rock
to the ore.—Clarke’s analyses’ show that igneous rocks carry an
average of o.1 per cent of manganese oxide, and many basic rocks
carry from 0.2 to 0.9 per cent. Where basic dikes have cut an
ore body, they doubtless contribute manganese to the waters
circulating in the deposit. The ore of the Haile mine, in South
Carolina, is cut by basic rocks; and the ore bodies of the Delamar
mine, in Nevada, are crosssed by a basic dike. Both of these
deposits show secondary enrichment of gold; and in both the
better ore is found along the dikes. In general, however, the
manganese from the country rock cannot safely be assumed to
have migrated extensively into the ore deposit, for many analyses
of mine waters do not show manganese; but where manganifer-
ous rocks are intimately fractured and filled with seams of ore it
would be supposed that the reactions requiring manganese could
take place.

In my own experience I have found only trivial stains of man-
ganese in those lodes where it was not present in the gangue of
the primary ore; and, in view of its wide distribution in igneous
rocks, I believe that the lateral migration of manganese into the>
ore under the conditions which generally prevail is very subordinate.
Though the amount so contributed may facilitate the solution of
gold, it is probably inadequate to form sufficient higher manganates
or similar salts to suppress effectively the action of ferrous sul-
phate. Under such conditions the gold could not travel to the
reducing-zone below the water level, but would be precipitated
practically at the place where it had been dissolved.

6. Concentration in the oxidized zone——The concentration
of gold in the oxidized zone near the surface, where the waters

t Bulletin No. 330, U.S. Geological Survey (1908).

MANGANESE IN GOLD DEPOSITS AI

remove the valueless elements more rapidly than gold, is fully
treated by T. A. Rickard in his paper on the “‘Bonanzas in Gold
Veins.”’* Undoubtedly this is an important process in lodes which
do not contain manganese, or in manganiferous lodes in areas
where the waters do not contain appreciable chloride. In the oxi-
dized zone it is sometimes difficult to distinguish the ore which
has been enriched by this process from ore which has been enriched
lower down by the solution and precipitation of gold, and which,
as a result of erosion, is now nearer the surface. It cannot be
denied that fine gold migrates downward in suspension; but in
all probability this process does not operate to an important
extent in the deeper part of the oxidized zone. If the enrichment
in gold is due simply to the removal of other constituents, it is
important to consider the volume- and mass-relations before and
after enrichment, and to compare them with the present values.
In some cases, it can be shown that the enriched ore occupies in
the lode about the same space as was occupied before oxidation.
Let it be supposed that a pyritic gold ore has been altered to a
limonite gold ore, and that gold has neither been removed nor
added. Limonite (sp. gr. from 3.6 to 4), if it is pseudomorphic
after pyrite (sp. gr. from 4.95 to 5.10) and if not more cellular,
weighs about 75 per cent as much as the pyrite. In those speci-
mens which I have broken, cellular spaces occupy in general about
ro per cent of the volume of the pseudomorph. With no gold
added, the ore should not be more than twice as rich as the primary
ore, even if a large factor is introduced to allow for SiO, removed
and for such cellular spaces.

Rich bunches of ore are much more common in the oxidized
zone than in the primary sulphides of such lodes. They are
present in some lodes which carry little or no manganese in the
gangue, and which below the water level show no deposition of
gold by descending solutions. Some of them are doubtless residual
pockets of rich ore which were richer than the main ore body when
deposited as sulphides, but others are doubtless ores to which gold
has been added in the process of oxidation near the water-table
by the solution and precipitation of gold in the presence of the

t Trans., XX XI, 198-220 (1901).

42 WILLIAM H. EMMONS

small amount of manganese contributed by the country rock.
In view of the relations shown by the chemical experiments it is
probable that a very little manganese will accomplish the solution
of gold, but that it requires considerably more manganese to
form appreciable amounts of the higher manganese compounds
which delay the deposition of gold, suppressing its precipitation
by ferrous sulphate. In the absence of larger amounts of the
higher manganese compounds, the gold would probably be pre-
cipitated almost as soon as the solutions encountered the zone
where any considerable amount of pyrite was exposed in the
partly oxidized ore. From this it follows that deposits showing
only traces of manganese, presumably supplied from the country
rock, are not enriched far below the zone of oxidation.

7. Vertical relation of deep-seated enrichment in gold to chalco-
citization.—In several of the great copper districts of the West
gold is a by-product of considerable value. In another group of
deposits, mainly of middle or late Tertiary age and younger than
the copper deposits, silver and gold are the principal metals, and
copper, when present, is only a by-product. . But in some of these
precious-metal ores chalcocite is, nevertheless, the most abundant
metallic mineral, often constituting 2 or 3 per cent of the vein
matter. Frequently it forms a coating over pyrite or other
minerals. Some of this ore, appearing in general not far below
the water-table, is fractured, spongy quartz, coated with pulver-
ulent chalcocite. It frequently contains good values in silver, and
more gold than the oxidized ore or the deeper-seated sulphide ore.
Clearly, the conditions which favor chalcocitization are favorable
also to the precipitation of silver and gold.

The exact chemical reaction which yields chalcocite is not
known. At 100° C., according to Dr. H. N. Stokes,’ the reaction
with pyrite is probably about as follows:

5Fes,-+-14CusO,- 12H O—7 Cus shiesO,- 12,50).
In the cold, the reaction may differ in details, but: without doubt
much ferrous and acid sulphate is set free. Attendant reactions

Unpublished. MSS quoted by Lindgren in Professional Paper No. 43, U.S.
Geological Survey, 183 (1905), and in Weed’s translation of Beck’s textbook.

MANGANESE IN GOLD DEPOSITS 43

confirm this statement; for, if calcite is present, gypsum is formed
by the reaction of H,SO, on lime carbonate; and, if the wall-
rocks are sericitic, kaolin is formed by the acid reacting upon
silicates, the potash going into solution as sulphate. The abun-
dant ferrous sulphate must quickly drive the gold from solution,
and it apparently follows that there may be no appreciable enrich-
ment of gold below the zone where chalcocitization is the prevail-
ing process.

VI. REVIEW OF MINING DISTRICTS

1. If gold is more readily dissolved in manganiferous deposits,
it would be supposed that placers form less readily from pyritic
manganiferous lodes than from lodes containing no manganese. |
If, in areas where the waters carry appreciable chlorine, placers
have formed as extensively from such lodes as from lodes free
from manganese, then the hypothesis fails.

2. The manganiferous lodes, in areas of chloride waters, as in
the undrained areas of the Great Basin, should in general show
less gold at the outcrop and in the upper portion of the oxidized
zone than below. Im silver-gold deposits, however, silver, on
account of the insolubility of the chloride, may remain, or be
concentrated, in the oxidized manganiferous zone. Bunches of
rich gold ore carrying oxidized manganese in the oxidized zone
are not necesssarily fatal to the theory; for, as already stated, these .
are probably residual from the zone of secondary enrichment.
An extensive enrichment in gold of the oxidized manganiferous
ores at the surface, which are shown not to be residual from the
zone of secondary ores, would indicate that the selective processes
lack quantitative value, if the waters carry chlorine, and if the
primary ores, from which the manganiferous oxidized ores are
derived, carry appreciable pyrite to supply sulphate.

3. If in certain lodes gold migrates below the water-table, it
should be precipitated quickly by ferrous sulphate. But MnO,
converts ferrous sulphate to ferric sulphate, which does not pre-
cipitate gold. Hence, MnO, favors the solution of gold, and
converting ‘the ferrous salt to ferric sulphate removes the pre-
cipitant. Consequently, if auriferous lodes show enrichment in

44 WILLIAM H. EMMONS

the deeper zone but related to the present surface of the country,
the manganiferous lodes should, the other favorable conditions
provided, show greater differences in values with respect to gold
than lodes free from manganese.

Gold provinces of the United States —As Lindgren’ pointed out
in 1902, the principal gold deposits of the United States may be
divided into four groups. ‘The deposits of each group belong mainly
to one metallogenetic epoch, and certain relationships are clearly
shown. ‘This classification, which has thrown much light on the
genesis of the deposits, is useful as an instrument for study and for
comparison of the deposits with respect to the problem of the
migration of gold in them.

t. The Appalachian gold deposits, and those of the Home-
stake type in South Dakota, are the most important representa-
tives of the oldest group. ‘These deposits generally yield placers,
are usually low grade below the water level, and are singularly free
from bonanzas. They are, in general, not greatly leached near
the surface, and may have been enriched by the removal of other
material more rapidly than gold. At only one of them, the Haile
mine, in South Carolina, it is thought probable that gold has
been carried below the water level. Judging from descriptions,
practically all of these deposits are free from manganese.

2. The California gold veins and related deposits in Nevada
(Silver Peak) and in Alaska (Treadwell, etc.) are younger than
the Appalachian deposits, and were probably formed in the main
in early Cretaceous times. These deposits, where physiographic
conditions are favorable, have generally yielded rich placers. At
many places, moreover, the ore is worked at the very surface, and,
there is very little evidence of the migration of gold to the deeper
zones. In the places where detailed work has been done, rhodo-
chrosite is never a gangue mineral, although manganese oxide does
occur in traces in the country rock, and rhodochrosite is found in a
few places in veinlets in the mining districts but not associated with
the gold veins.

3. The deposits of the third group are later than the early

t“The Gold Production of North America,” Trans., XXXIII, 790-845 (1903);
““Metallogenetic Epochs,” Economic Geology, IV, No. 5, 409-20 (Aug., 1909).

MANGANESE IN GOLD DEPOSITS 45

Cretaceous, and some of them are probably early Tertiary.
They are extensively developed in Montana, Nevada, Utah, and
Colorado. Mr. Lindgren calls this group the Central Belt. Many
of its deposits have yielded considerable gold, and in certain other
districts very closely related genetically (Butte, Georgetown
silver-gold lodes, Cortez Nevada, Tintic, etc.) much gold has
been obtained as a by-product to copper or silver mining. Some
of these deposits have yielded placers and some have not. At
Philipsburg and Neihart, Mont., Georgetown, Colo., and else-
where, the deposits show a secondary enrichment of silver below
the water-table. At Philipsburg, and probably at some other
places, an enrichment in gold accompanies this concentration of
silver. Some of the lodes of group 3 carry much manganese, and
some carry none. Present data are meager for most of these dis-
tricts. The determination of gold from the surface down in a
large number of deposits would serve as a useful check to the con-
clusions based upon the chemistry of the processes involved in its
solution and precipitation.

4. Group 4 includes the most recent ore deposits in the United
States. All of them are Tertiary, and most of them are Miocene
or Pliocene. In general, they were formed relatively near the
surface, and in some places it is highly probable that not more
than a thousand feet of vein material has been removed by erosion
since the ores were deposited. The majority of these deposits
carry silver, and in many of them its value is greater than that of
the gold; but they have supplied, notwithstanding, about 25 per
cent of the gold production of North America. They are typi-
cally developed in Nevada (Comstock, Tonopah, Goldfield, Tus-
carora, Gold Circle); California (Bodie); Idaho (De Lamar);
South Dakota (later than Homestake type); Colorado (Cripple
Creek, Idaho Springs, Rosita Hills, San Juan, etc.); Montana
(Little Rockies, Kendall, etc.). Many occurrences in Mexico
should probably be placed here, also. The deposits of this group
have not supplied much placer gold. Many of these deposits are
in arid countries, where conditions for working placers are not
favorable; but even those in well-watered districts supply rela-
tively little placer gold. Manganese is abundant in some of

46 WILLIAM H. EMMONS

these deposits (Comstock, Exposed Treasure, Tonopah); it is
very sparingly present in others (Little Rockies); in still others
(Goldfield) it is almost entirely absent.

A few small placers are associated with the manganiferous lodes,
although at some places they seem to have been derived from
veins near by which are not manganiferous. Many of the Cali-
fornia veins carry rich ore at the very surface, but the Tertiary
gold veins are generally richer in gold a few feet below the surface
than at the outcrop. Doubtless, many of them would have been
overlooked if it had not been for the concentration of horn silver
and argentiferous pyromorphite at the surface.

It thus appears that practically all of the manganiferous gold
deposits of the United States, so far as they have been described,
may be included in groups 3 and 4; that nearly all described
deposits where relations indicate a migration of gold belong to
the same groups; that placers are much less abundantly devel-
oped than in groups 1 and 2; and that outcrops less frequently
supply gold; that secondary enrichment below the water-table,
if carried on at all, proceeds with extreme slowness in groups
1 and 2, but may be more pronounced in deposits of groups 3 and
4. Not all deposits of 3 and 4 carry manganese, however, and
those which do not carry it show relationships more nearly approxi-
mating those which hold in the California gold veins. The migra-
tion of gold in the more important auriferous deposits of the
United States is discussed in some detail in Bull. 46, Amer. Inst.
Mining Engineers, 817-37.

LOCAL DECOMPOSITION OF ROCK BY THE CORROSIVE
ACTION OF PRE-GLACIAL PEAT-BOGS

EDWIN W. HUMPHREYS AND ALEXIS A. JULIEN

While the layer of decayed rock which once overlay the region
around New York City has been generally planed off by the conti-
nental glacier, certain small isolated spots have been noted from
time to time in which masses of rotten schist still remain. Their
decay is commonly attributed to weathering action, and their escape
from the glacial scour at such points, to their probable protection
by projecting eminences of rock under whose lee they are supposed
to lie.

Excavation in schist—An unusually large occurrence of this
kind has been recently exposed in an excavation for a cellar on the
east side of the junction of Southern Boulevard and Westchester
Avenue, Borough of the Bronx, New York City, whose general
form and dimensions‘ are shown in Fig. 1.

The gneissic schists here present the foliation with usual high
angle, 70° to 90°; strike N. 23° E.and S. 23° W. Asmall anticlinal
fold crosses the strata, as shown in the diagram (Fig. 1) whose
axis runs N. 52° E. and S. 52° W. A small overthrow is shown in
its cross-section at the northern end, and at its southern end it
pitches to the southwest at an angle of about 30°. The rock con-
sists chiefly of a fine granular aggregate of quartz, with much
biotite in minute black scales, and more or less disseminated white
feldspar. Throughout the western half of the excavation, however,
many thin seams of pegmatitic gneiss and of gray quartz are
intercalated, up to nine inches in thickness.

Pegmatite dike-——A pegmatite dike, about five feet in width,
nearly vertical, also cuts obliquely through the schists, with a course
of N. 30° E. and S. 30° W. At many points, small projections or
apophyses branch out into the schist along its course and are,

1 We wish to express our indebtedness for these data to Mr. C. S. Shumway,
superintendent of the Construction Department of the American Real Estate Co.

48 EDWIN W. HUMPHREYS AND ALEXIS A. JULIEN

apparently, connected with some of the pegmatitic seams inter-
calated in the schist. The position of the dike, on the west side
of the overthrow in the anticline at the north end, suggests that it
has there acted as an obstacle against the northwestward thrust
of the beds and so produced the westward distortion of the upper
side of the fold. The pegmatite itself is an aggregate of grayish
quartz, white feldspar, and very little mica, of the rather uniform
medium texture usual in the dikes of the Bronx region, with grains
rarely exceeding two or three inches.

SOUTHERN BOULEVARD.

Oy YY

i] Ue

AL al

Dike Decomposed Schist Undecomposed Schist

Fic. 1.—Relative positions of decomposed schist, undecomposed schist, and
pegmatite dike.

Decay of schist—In the eastern part of the excavation, the rock
was hard and sound, and needed to be blasted for removal. In the
western, the schist was thoroughly decomposed throughout to an
undetermined depth, so soft that it was easily removed with pick
and shovel, bluish to purple gray in color, and in texture passing
from a gritty aggregate almost to a clay; the latter corresponded
closely to the glacial clays of similar color commonly found about
the city. The two tracts, fresh and decayed, were separated by
an exceedingly sharp contact (the line A—B in the diagram), so that,

DECOMPOSITION OF ROCK BY CORROSIVE ACTION 49

in the cross-section at the north end (at the point B), the hand
placed across this line would rest on the left upon the decomposed
schist, easily dislodged by the touch of a finger, and on the right
upon the hard fresh rock. This contact is shown in Fig. 2, with
the decayed schist on the left, and on the right the same rock in
rugged, hard condition. The trend of this sharp division line was
N. 28° E. and S. 28° W., approxi-
mately parallel to the course of
the dike. However, in the cross-
section, a few seams of decayed
rock were noticed to the east of
this line, descending a yard or
more into the solid schist. The
same section showed that the
upper eroded surface of the schist
descended from a height of four-
‘teen feet at the point B along
the northeast wall, to a height
of seven and one-half feet, in a
distance of fifty-four feet to the
corner on Westchester Avenue.
Decay of pegmatite.—A similar
decay has atiected the pegmatite, Fic. 2.—Contact of decomposed and
muchofwhosefeldsparhaspassed — ndecomposed schist.
into a white kaolinic clay, so
that this rock also was easily removed by means of the pick.
Although it is even now much more tough and solid than the sur-
rounding schist, it appears to have been planed off by the ice at
about the same level, as shown near the bottom of the cross-section
(Fig. 3) where the north end of the dike strikes the wall at West-
chester Avenue. Above it lies a layer of till, and then a slab of
granitic gneiss. It should be also noted that the decay above
described is entirely exceptional in this region. For example, in
another excavation in the schist, a few hundred feet to the north,
the same schist was found practically undecomposed and sound.
So also as to the numerous other pegmatite dikes in the Bronx, all
we have observed are solid and show almost no decay.

50 EDWIN W. HUMPHREYS AND ALEXIS A. JULIEN

Glacial deposits —The layer of glacial deposits, which overlies
the schist at this locality, as shown in the following generalized
cross-section along Westchester Avenue (Fig. 4), about fifteen feet
from the street level to the greatest depth in the excavation, is yet
to be considered.

Fawn-colored micaceous sand with some trap bowlders. . . ves
Slab: of pega titicsomelsstaare pees eee ae ee I
Gray sandy gull swith staatedsbowldersem arc a ee 3
Slabyonjpegmia titleremeiss sane i sa ae oes ne I
Gray till irich amma caceousiclay ay ees eset eee i-3
Slabt ok pesmatiticremeisses serie srneyra yen nie eae oie t-3
Gray bowlder: clawys.werrecsxs tye cs case canes Mata ete barb cere near 3-3
Slab sofpesmatiticremelssien. 00 ashen rc hae eer 3-23
Blue-etay bowldericlayincn ac, oe Note cleo Pee anes vee i
Slabs of pegmatitic gneiss and Manhattan schist.......... If
Blue-eray bowlderm clays 4 cone seeeie se ree eee I
Decayed schist in place with vertical foliation, intercalated

Withethinuseams Olspe cimatice ss. ci crn neers ars aera 6-83

The remarkable deposit of ground moraine, which here rests
upon the upturned edges of the schist, is thus found to consist
largely, in the two hundred feet of section exposed along the two
avenues, of a succession of huge, overlapping sheets of granitic
gneiss separated by layers of sand and till or bowlder clay.

The gneiss slabs,-of which a series of from four to eight are
shown in any particular part of the section, consist of a rather
fine-grained granitoid gneiss of constitution similar to that of the
pegmatite. Their dimensions in cross-section vary from about 3
to 35 feet in length, and in thickness from 1 to 30 inches or more.
There was no opportunity to determine their real shape, but appar-
ently they consisted of flat sheets, often thinning down toward the
edges to an inch or less. Some show fracture and faulting in place,
as by the effect of superincumbent pressure (Fig. 5), and occasion-
ally the extension of such a slab toward its edge into a thin pliable
sheet, one or two inches thick, reveals a marked curvature as by
pressure from above (Fig. 6). Toward the bottom of the section,
they may be accompanied by a few small sheets of fine biotitic
schist, like that of the underlying rock in place. The granitoid
gneiss in these slabs shows partial to thorough decay, so that they

DECOMPOSITION OF ROCK BY CORROSIVE ACTION 51

mark the cross-section by a series of conspicuous, white, kaolinic,
lenticular bands, contrasting with the intervening layers of dark
till.

The bowlder clay
of these intervening
layers is very dense
and compact, some-
times sandy, some-
times rich in mica
and clay, and con-
tains few pebbles
and occasional bowl-
ders up to about two
feet in diameter,
which may show
sharp, glacial striae. Fic. 3—Manner in which the pegmatite dike was
These consist partly planed off by the glacier.
of rocks of the vicin-
ity, quartz from seams, granitoid and hornblende gneiss, etc., and
partly of rocks from the Palisades on the west bank of the Hudson
River, about five
miles distant, viz.,
diabase, coarse red
sandstone, indurated
shale from the con-
tact underlying the
trap, etc. Nearly
all these bowlders
are hard and un-
decomposed.

At several points
where such a trap
bowlder rested im-

Fic. 4.—Section along Westchester Avenue. mediately upon a
granite slab, the
latter was deeply indented, its folia separating and rising a little
around the bowlder, above the upper level of the slab. Immediately

52 EDWIN W. HUMPHREYS AND ALEXIS A. JULIEN

under the bowlder, the folia of the granite showed differentiation
and deformation as by a crushing force from above; but the lower

Fic. 5.—Fracture and faulting shown by one of the

transported slabs.

level: or mther sslalp
rarely showed much
if any depression in

a direction below the

bowlder (Figs. 7 and
8). .

Cause of decay.—
Inseeking to account
for this peculiar de-
composition in one
tract of the schist,
the action of the
weather is barred
out, on account of
the absence of such

decomposition in adjoining areas of schist, as well as in the other
pegmatite dikes of the Bronx region, the absence of concentration

of iron oxide from
agencies of mere
oxidation,’ and the
sharp line of de-
markation between
this tract and the
unchanged schist.
All the facts point to
some agency which
could produce deep
local corrosion, and
the considerable
leaching shown by
the removal of iron
oxide and by the

Fic. 6—Curvature produced by pressure on a trans-

ported slab.

residues of white kaolin. The presence of the pegmatite dike
across the middle of this tract, and its parallelism to the sharply

t Stremme, Zis. f. prkt. Geol., XVI (1908), 128.

i
i
i
;

DECOMPOSITION OF ROCK BY CORROSIVE ACTION 53

defined border of the decay on the east, at once suggest its possible
connection in some way with this chemical action. This might be
referred to an attack of the schist by the magmatic vapors, “‘ the
post-volcanic gas exhalations’’ of Weinschenk, accompanying the
eruption of a dike of acid constitution, but for the entire absence
of such effect in the vicinity of the tourmaline-bearing granite
dikes which abound throughout this region. Taking all the facts
here observed, we conclude that at this locality we find proofs, in
the deep erosion, solution, and leaching, of the long-continued
action of humus acids from peat-water, resulting in products which
correspond to the
‘““Grauerde”’ of Ger-
many, studied by
Ramann, Wiist,
Selle, Stremme, etc.*
It seems probable
that this deep local
decay of both gneis-
sic schists and the
inclosed pegmatite
records the continu-
ous corrosion of an
ancient pre-glacial
peat-bog. The east- Fic. 7.—Showing how a bowlder was forced into one
ern border of the bog of the transported slabs.
appears to be marked
by the sharply defined eastern limit of this decayed tract. The
wall of impervious pegmatite may perhaps have formed a dam to
confine the corrosive liquids, as in a vat, along this edge of the
ancient bog; in such case the limit of corrosion would naturally lie
parallel to the line of the dam. i

With the prevalent tendency to attribute the formation of the
original layer of: laterite over the northern part of our continent
mainly or exclusively to weathering by meteoric agencies, there
seems to have been little recognition of the view above suggested
in explanation of the local instances of deeper decomposition of

tH. Rosler, Zis. f. prkt. Geol., XVI (1908), 251-54.

54 EDWIN W. HUMPHREYS AND ALEXIS A. JULIEN

crystalline rocks which have escaped the glacial scouring. It
therefore may be added that we find abundant evidence of the wide
distribution of tundra and peat-bogs all over this region, for a long
period before the advance of the continental glacier as well as since
its retreat. In the adjoining region, Westchester County, Mather
recorded, sixty years ago, observations on peat-bogs, covering in
the aggregate nearly 400 acres. Throughout the Bronx tract, in
all directions around the locality we have described, we have noted
many remnants of these, in street and house excavations, which
have not yet been destroyed by the advances of the great city.
; These now vary
widely in area and in
depth. A few in-
stances will be pre-
sented to show that
this form of chemical
corrosion must have
been here an active
factor in degrading
even the elevations
of the rock-surface.
Thus, along the
low valley now oc-
Frc. 8—Another bowlder that was forced into a slab. cupied by Morris
Avenue, the depres-
sion in the glaciated surface was formerly filled with peat, even
now particularly well shown in the vicinity of 170th Street. In
filling in this street with rock, the peat was forced up in places to
a height of ten feet on each side, and its surface cracked in all direc-
tions, revealing pockets of fresh-water shells. Thence the bog
certainly stretched for a quarter of a mile, with a width of several
hundred feet; while there is evidence of its former extension south-
ward, probably as far as the Harlem River, and northward for an
indeterminate, but long, distance. At 178th Street and Honeywell
Avenue, a peat-bog yet remains and has recently been partially
excavated, of which the original area, we estimate, must have occu-
pied several hundred acres along the low valley. Its depth, as

DECOMPOSITION OF ROCK BY CORROSIVE ACTION 55

proved by driven piles, reached, here, twenty-two feet. The
bed of this formerly great swamp is now crossed by Daly
Avenue, Honeywell Avenue, Southern Boulevard, Mapes Avenue,
and Prospect Avenue. At Daly Avenue near Tremont Avenue,
the depth of the peat was such that it was found necessary
for foundations to drive piles forty-five feet in length. Not
only were the lower grounds so filled up, especially the long
valley depressions, such as those of the Bronx River, Eastchester
Creek, Tibbit’s Creek, etc., but thin local sheets seem to have
rested in the hollows among the rounded hummocks of the glaciated
upland; these are in part still represented by little marshes, or the
ponds in the various parks. It appears but a moderate estimate to
assert that at least one-third of the surface of this region was once
covered by an almost continuous sheet of fresh-water bog, out of
which the higher elevations protruded as knobs of forest-covered
rock. Along the adjoining coast at Hunt’s Point, Bartow, etc.,
these ancient bogs have been since overlaid, during the subsidence
now in progress, by a sheet of salt meadow, surrounding a large num-
ber of small scattered islets of now bare outcrops of gneiss and
granite.

Further evidence of the early and long activity of organic acids
in solution, removal, concentration, and deposit of iron oxide from
the surface of these rocks is afforded by numerous accumulations
of bog iron ore once found throughout this region as well as over
Manhattan Island. Though generally small, some of these were
of sufficient volume to be of economic importance and use two
hundred years ago.

Escape of decayed schist from removal by the glacier.—There was
here no knob or eminence on the northwest for the protection of
the softened schists from the scour of the ice moving from that
direction. On the contrary, a low valley lies on that side, which
we presume was occupied by the peat-bog. The pegmatite itself,
though softened, probably served long as the main protection of
the schist, in connection with the pegmatitic branches and seams
intercalated in the schist in this part of the tract. The next result-
ing condition was apparently the erosion of this surface of the
schist in an inclined plane, tending to lift the edge of the ice-sheet

56 EDWIN W. HUMPHREYS AND ALEXIS A. JULIEN

up to the surface of the solid rock. The last phase appears to have
been the plucking-up of huge thin slabs from a mass of thinly
foliated granite, somewhere in the valley adjoining on the west,
and their deposit as a ground-moraine over this inclined plane,
with intervening sheets of bowlder clay, in a kind of natural
masonry, for further protection of the underlying soft schists.

Evidences and measure of the superincumbent pressure.—Soft as
this granite is now found, it is obvious that it must have possessed
‘much strength and rigidity at the time of its transport by the ice
in the form of slabs, mostly from a few inches up to a foot in thick-
ness, although commonly ten to twenty feet or more in greatest
extension. ‘The pressure upon them, as well as their rigidity, is
shown by the frequent fractures and faulting, and the bending of
thin edges. Still more significant is the crushing of the rock within
the slabs at the contact with overlying bowlders of trap, which
have been pressed down into pockets in the granite. In one case
(Fig. 7) the bowlder appears to have been lifted subsequently some-
what out of its pit and the clay forced in beneath it. In another
(Fig. 8) the crushed granite rises around the imbedded bowlder,
which was eighteen inches in diameter, as if the rock was almost
plastic, either on account of the great pressure or of its own softened
condition, or both. We had almost hoped to have found here a
natural record of the weight of the superincumbent ice, and there-
fore of its thickness, by estimating the volume of the granite crushed
beneath the imbedded portion of the bowlder. This was found
impracticable, from the impossibility of determining the crushing
strength of the rock at the time of its penetration. However, we
already possess some measure of the thickness of the ice-sheet in
this region in the presence of glacial striae, often an inch in depth,
at points 250 to 300 feet in elevation; e.g., on the edges of the
gneiss over the summit of Inwood Heights, Manhattan Island, and
on the trap along the edge of the Palisade escarpment, on the west
side of the Hudson River. These imply a pressure which could
hardly have been exerted by a sheet of ice less than 1,000 feet in
thickness.

ONDE, FOCUS, OF POSTGLACIAL UPLIFT NORTH OF
THE GREAT LAKES

J. W. SPENCER
Washington, D.C.

The first determination of the approximate location of the focus
of postglacial uplift, based upon the amount of rise found in the
beaches about Lake Ontario and Georgian Bay, appeared in a
volume, to which access is difficult," and for this reason the passage
may be cited, as the revision to be given below will be found in
general conformity with the previous conclusions.

If the axis of maximum elevation for the various triangles about Lake
Ontario and Georgian Bay be produced, they meet near latitude 51° N., and
longitude 743° W., a few miles west of Lake Mistassi and east of the southern
end of James’ Bay. Although mainly radiating from the focus, the axes of
maximum elevation for the different triangles are not uniform, and are locally
modified, as along the western side of Lake Ontario, where there is found a
secondary axis of uplift to the east. Combining the more western axes with
those of the eastern end of the lake, another focus of uplift appears near the
“Height of Land”’ between Lake Ontario and Hudson Bay, in about latitude
48° N., and longitude 76° W. From the double foci it may be inferred that
the uplift reached its maximum along a line joining the foci, or that the axis
of maximum regional uplift was meridional and located along the eastern end
of Lake Ontario, increasing in amount until near the “Height of Land,” and
thence with a diminishing ratio, or even depression, towards the north.....
At any rate, it is in the region southeast of Hudson Bay that the maximum
differential elevation of the earth’s crust, which involved the Iroquois beach,
is to. be found.? ;

Since that time (1889), Gilbert, De Geer, Taylor, and recently
Goldthwaite have illustrated more or less fully the rise by isobars,
which is only another mode of expressing the same phenomena,
while Coleman has redetermined some of the triangles.

Combining additional measurements obtained from Fairchild
and Goldthwaite, I have recalculated the mean rise in the various
triangles from the present heights of the beaches about Lake

t Transactions of the Royal Society of Canada, VII, sec. iv, 189, read May 5, 1889.

2 J. W. Spencer, zbid., 189.

58 J. W. SPENCER

Ontario and Georgian Bay, The postglacial bulge is like a sheet
raised by an object thrust under it, the height increasing from out-
ward from the focus of rise, but we can differentiate it in triangles

Height 7] , of land
Al

FOCUS
OR

POST GLACIAL DEFORMATION

as originally determined in 1887-88
and revised in |9|0

| ia
Grand Bend
Hamiltoq

eal
f°? lev

and obtain the mean rate for each. These should cover the sur-
veyed region, and be as nearly equilateral or right-angular as
possible. Thus the following results have been obtained.

The mean rate of rise from the lowest points in the triangles
and the direction, based upon the height of the Iroquois beach,
cover the region of Lake Ontario.

iE FOCUS OF POSTGLACTAL UPLIFT 59

Triangles between
Hamilton, Lewiston, and Scarboro,! 2 feet, N. 22° E.
Lewiston, Rochester, Colborne, Ont., 2.5 feet, N. 17° E.
Rochester, Sodus, Trenton, Ont., 3.6 feet, N. 10° E.
Sodus, Rome, east of Watertown, N.Y., 5.5 feet, N. 3° E.

These lines converge approximately in lat. N. 49° E., and long.
76° W. With the revised figures, the longitude is found to be the
same, while the latitude is only 60 geographical miles north of the
original determination, with the meridian of maximum uplift
found to be just beyond the eastern end of Lake Ontario as origi-
nally computed.

Based upon the rise of the Algonquin beach east of Lake Huron,
the mean rise in the triangles is found to be:

Between
Grand Bend, Southampton, and Rosedale, 1.3 feet per mile, N. 35° E.
Holland Landing, Wyebridge, and Rosedale, 3.4 feet per mile, N. 23° E.
Bradford, Owen Sound, Wyebridge, 3.1 feet, N. 27° E.

Combining the former of these triangles with those about Lake
Ontario, the lines of rise from Grand Bend, and from Holland
Landing, converge to the same point as those from Lake Ontario,
but if the mean rate for the third triangle (which takes in a more
western equivalent) be used the focus will be in about lat. 48° N.

Upham, Taylor, and Leverett have found the rate of rise in the
region to the northwest to be of smaller amount, where Gold-
thwaite suggests that the rise also somewhat coincides with the
height of land as found by me farther east in 1888, where the
maximum amount is computed at some 250 miles north of Ottawa
City, or a few miles to the west of this meridian.

The inferences to be drawn from these observations are: (1)
that until a downward slope shall be found, we should conclude
that the rise described continues to near the region indicated,
beyond which the postglacial warping is downward; (2) that:
eastward of the 76th meridian, for any assumed latitude, the post-
glacial rise disappears and comes to be replaced by a downward
slope. This is a question that has given the writer much solicitude,
in an effort to determine the locus of downward warping in the

1 At a point 12 miles east of Toronto. Ii, in place of this, the elevation at Carl-
ton (5 miles west of Toronto station) be taken, the line of rise is found to be N. 27° E.

60 J.W. SPENCER

field. As the higher beaches have been found by all of us to indicate
the greatest amount of warping, we should not expect to find a
great amount in the altitudes of the Champlain marine deposits,
but we see these recurring at so many points to about 500 feet above
sea-level, that, upon examining their locations in the St. Lawrence
Valley, it is noticeable that they occur along segments of the circle,
roughly speaking, with the radii converging to the vicinity of the
focus found; while in receding toward Gaspé, New Brunswick, and
Nova Scotia the marine deposits rise only to lower and lower alti-
tudes. These data are well known, so that an undue demand on
the reader’s patience need not be made by their repetition here.
So also with regard to most of the elevations on the Iroquois and
Algonquin beaches. Again, the eastern equivalent of the warp-
ing of the Iroquois, south of Lake Ontario, and in the Mohawk
Valley, supports the hypothesis of declining postglacial warping in
that direction, after passing the eastern end of Lake Ontario.

The question of the location of the line of maximum post-
glacial elevation radiating from the region mentioned raises several
points in physical geography; one of these being the explanation
of the cause of the rise, as due to the disappearance of the glaciers,
for this locality was hardly the center of glacial dispersion. This
idea, however, is here thrown out for others to consider.

Since these notes were written, the admirable paper of Professor
Goldthwaite on the “‘Isobases of the Algonquin and Iroquois
Beaches”? has appeared. While the treatment of the postglacial
warping by isobasic lines is scarcely other than a different mode
from determining the mean rise in the various triangles, yet each
has a significance of its own. The isobases indicate a regional
rise toward the Laurentian axis. The triangles carried this rise
to the “ Height of Land” and show the locus of maximum rise
north of the Great Lakes.

NOTE ON THE ACCOMPANYING Map

The triangles about Lake Ontario are based on the instrumental measure-
ments of the Iroquois beach, at the places on the map; those east of Lake
Huron, on the measurements of the Algonquin beach. Height, at Rome and
Sodus after Fairchild, of Holland Landing and Rosedale (in place of my Kirt-
vill) after Goldthwaite. The other points are from my own surveys.

A GEOLOGICAL ROUTE THROUGH CENTRAL ASIA
MINOR

FROM AFIUN KARA HISSAR VIA SIVRI HISSAR, ANGORA,
SUNGURLU, AND THE MALYA TCHOL TO CAESAREA

WILLIAM T. M. FORBES, PH.D.
New Brunswick, N.J.

The following paper is the summary of a series of notes taken
in the summer of 1907, in connection with the Cornell Expedition
to Asia Minor and the Assyro-Babylonian Orient. In a worked-
over area like most of Europe and the United States, such a series
of observations, probably somewhat inaccurate because of their
hurried character, would add little to our knowledge. But in
central Asia Minor the case is far different. Travel has been
difficult and travelers are few. The men who have studied the
geology of even a part of central Asia Minor could be numbered
on one’s fingers, and but one or two of them had the advantage
of being trained geologists used to the work and to the country,
and with the leisure to stop and examine.

For this reason it is that these notes represent new territory
in practically their whole length. At certain points only did we
cross (geologically) known territory.

The observations were taken from horseback, as had to be
done under the conditions of travel. It was rarely possible to
stop to investigate a place or to visit again one that had been
passed. This must have resulted in some errors, especially as
the caravan could not carry any great weight of specimens.

' Frequently the rocks were fossiliferous, making their date
certain, but unconformities were so frequent that it was not
wholly safe to consider surrounding rocks as of the same date as
the fossiliferous strata. Specimens were preserved wherever
fossils were found (the majority were Eocene nummulites). These
are deposited in the museum at Harvard and a study of them by

62 WILLIAM T. M. FORBES

specialists would certainly result in a more accurate dating of
many strata.

Because of the peculiar conditions the description will usually
follow the itinerary of the party, which was as follows: Afiun
Kara Hissar, Phrygian Monuments, Aktash Kopri, Sivri Hissar,
Gordium, Polatly, Hammam (Haimané), Giaour Kalesi, Angora
(Enguri), Assi Yuzgad, Yakshy Khan, Izz-ed-Din, Sungurlu,
Boghaz Koi—with a sidetrip to Eytik—Yuzgad, Medjidié, across
the Malya Tchol to Bash; Hadji Bektash, Kara Burun, Avanos,
Inje Su, and Caesarea (Kaisari). At this point the author was
obliged to leave the party and hurry back to Constantinople. A
few notes were taken from the train north of Afiun Kara Hissar
which have been used to help out the map of that section.

Distances are reckoned roughly in hours (at the rate of a walk-
ing horse, three miles an hour), as that is the usual unit of measure-
ment in the country.

The principal geologist of Asia Minor was Tchihatcheff,? and
his map remains the only one of much of the country. His work
is now fifty years old and an experienced modern student would
doubtless modify much of it. Still to the present time the man
who has his books at his elbow will not miss very much of what is
known of the geology of the eastern two-thirds of the territory.

Yuzgad, and on an even grander scale, Caesarea, are in the
center of regions which should prove exceedingly interesting.
The complex resulting from several periods of igneous action
makes a fascinating puzzle to disentangle. At these points I can
add almost nothing to Tchihatcheff’s account, but can fully verify
the existence of the confusion he reports.

Because of the impossibility of determining the date of most

tT have not been entirely consistent in my transliteration of native names of
places, etc. There is no established method, and two books on the country
will hardly agree in their methods. J and y (vowel), in particular, represent
different sounds in Turkish, but they are not sharply defined and I should perhaps
have used y more freely than I have. The distinction between g and & also generally
represents a mere difference in Turkish spelling. Q might perhaps have been used
more freely, following Arabic precedent.

I follow the spelling of Tchihatcheff’s name as it appears on the title-page of his
large work—in French. It is spelled differently in the German reports of his travels.

GEOLOGICAL ROUTE THROUGH ASIA MINOR 63

of the rocks, they are classified on the maps rather from super-
ficial characters. I have specially indicated the points where
fossils have been found. The rocks may be grouped as igneous
(of various sorts), metamorphic (largely Paleozoic where their
relationships are known), obliquely stratified (Mesozoic and
Eocene, especially the latter), and horizontally bedded sedimen-
taries (Miocene and later as a rule). Thorough tracing-out of
the relationships of strata and thorough collecting of the fossils
can alone give a much more accurate knowledge of the dates of
the various deposits of Asia Minor.

In connection with the regular archaeological report of the
expedition I expect to publish this matter in a less technical way
and with reference rather to its interrelation with the various
past peoples of Asia Minor and their culture.

I wish to express my indebtedness to the members of the ex-
pedition in many ways, and especially to Jesse E. Wrench, who
did most of the topographic work; also to Professor J. B. Wood-
worth, under whose direction and advice this report was prepared,
and to the other authorities of Harvard University who have
helped me in the matter of books, instruments, etc.

MOUNTAINOUS PHRYGIA

Comparatively few notes were taken in this district, and no
specimens were collected. The substratum of the country is
metamorphic, appearing as schists along the railroad cut between
Ihsanié and Diiver (Deuyer), at the entrance to the mountainous
section southwest of Ayaz In, and in smaller bands east of Yazili
Kaya. There were also three outcrops in the Sakaria plain, one
a considerable band at the eastern end of the Yazili Kaya lime-
stones, and the others east and west of Aktash Kopri, as shown
on the map. Quite as frequently the metamorphic rocks were
limestones. This was the case along the railroad, north of the
mapped area for a considerable distance, and also in a large area
all about Yazili Kaya.

Overlying the metamorphic rocks are everywhere igneous
rocks, Neocene in date. These lie in horizontal beds, lavas, or
tuffs, and are sometimes so rotted as to be indeterminable. Of the

64 WILLIAM T. M. FORBES

same period also are several local deposits of sandstone and con-
glomerate. These are cut by the railroad near Hammam and
elsewhere; they form the basis of many of the sculptured rocks
of the country. More frankly volcanic are the white tuffs of
Ayaz In, and the lava mesas which make a dominant feature of
the landscape east of the railroad, and all about Yazili Kaya.

The lacustrine gravels of the Sakaria Valley approach quite
close to Yazili Kaya on the east and mark the northeastern bound-
ary of Mountainous Phrygia.

As reported by Tchihatcheff and Hamilton the region south of
the author’s route is of the same character, but the dominance of
igneous rocks becomes less. The conspicuous volcanic necks of
Afiun Kara Hissar are well described by Tchihatcheff and others.

THE SIVRI HISSAR RANGE

Passing over the lacustrine plains of the Sakaria River for the
present, we reach the next point of interest in the Sivri Hissar
Mountains, conspicuous among them Kodja Bel. At this place
the stratified rocks would seem to belong to the same group as
those in Phrygia, but the core of the range is a granite (a syenite
in the popular sense of the word, as it is a fine-grained granite
with little or no mica). East of Bala Hissar there is an area of
limestone on the very top of the range, surrounded on both sides
with the syenite, apparently lifted up on top of it. Near the city
(Sivri Hissar) there is a complex of metamorphic rocks (schists
and gneiss), through which the road passes on the east side of the
mountains. Kodja Bel, a conspicuous peak southeast of the
city, and the Kaimas peak to the northwest, seem to be similar.

Tchihatcheff has reported on the northwestern part of the
range; conditions are essentially the same, an alternation of
syenite (granite) with various metamorphics.

GORDIUM AND POLATLY

The neighborhood of Polatly, unlike the preceding localities,
has fossiliferous rocks, making it possible to fix this district as
Eocene. Nummulites are the dominant feature, as elsewhere
in Asia Minor eocenes.

GEOLOGICAL ROUTE THROUGH ASIA MINOR 65

To the west of the Sakaria no Eocene rocks were found 7m sztu,
but the cairns built by the shepherds are of fossiliferous limestone.

Fic. 1.—Sketch of the hills southeast of Gordium, interpreted as a laccolith.
The stratified shales are indicated with fine oblique hatching; the lower trap is coarsely,
and the upper trap finely, cross-hatched. The baked layer of the shales is shown
solid black. Possible faults are indicated.

Fic. 2.—Cross-section through ABC. The symbols are the same as in the pre-
ceding figure.

Probably outcrops of the rock occur. On the east side of the
river the lacustrine plain is quite narrow, and is replaced by hilly
country. This is composed, to the south of Polatly, largely of
Eocene limestones, but farther north of light-colored (yellow or

66 WILLIAM T. M. FORBES

greenish) shales, which have the appearance of hardly consolidated
clays.

There were also many outcrops of a dense igneous rock, necks
southwest and east of Polatly, and sheets nearer to the village
and to the northwest. ‘To the northwest, as the plan shows, the
situation becomes quite complex; in the plan the strata are inter-
preted as representing a laccolith, with overlying sedimentary
rocks and flows, sloping away in at least three directions from its
uncovered core. The eastern part was, unfortunately, passed
over in the night, so that I cannot say whether the conditions were
the same on that side or not. Overlying the sedimentary rocks
was a sheet of lava. This had baked the clay red for the thick-
ness of about a foot; making a very conspicuous layer. The red
color was quite extensive toward the north, east of Gordium,
so probably the trap sheet had once been much larger, but has
been eroded off, leaving only the baked brick layer as a memento.
At present, of course, these deposits can only be marked as “ prob-
ably Eocene.”

Hamilton reports similar mixtures of sedimentary and trap
rocks north of Polatly, in the neighborhood of ‘‘ Begesch”’ oe
djez or Beikos ?).

HAIMANE

Separated, at least in the line of our route, by a region of recent
deposits, from the Polatly limestones and shales, there lies to the
east the strikingly arranged Haimané district. In the immediate
vicinity of Hammam no fossils have been found, though the
rocks (shales) look promising enough. At Kaya Bashy there were
plenty of shells in a limy conglomerate, apparently largely Anomias,
but they were so much injured in transport that one can hardly
determine whether the rocks belong with the eocenes of Polatly, or
with the Jura and Lias which other authors have reported to the
west of Angora. While Tchihatcheff, who has passed through the
district at right angles to our route, considers them as probably
Jurassic, I should incline rather to the other conclusion, especially
as some of the Polatly nummulites were in quite similar-looking
rocks.

- At any rate, they are sedimentary deposits, obliquely banded,

GEOLOGICAL ROUTE THROUGH ASIA MINOR 67

very brilliantly colored in red and yellow, and rarely obscured by
plant cover, so that their bedding can be traced for long distances.
No unconformities were noticed, but the point of transition between
the shales immediately about Hammam and the calcareous con-
glomerates and sandstones to the north was not seen. As reported
by Tchihatcheff these deposits must be very extensive to the
north of our route; in fact they and others similar dominate the
formations of central Asia Minor.

A gorge about an hour north of Hammam, near the village of
Arif, passes through a mass of much denser limestone, which
seemed to be conformable to the other deposits, but was very
different in appearance. It is indicated by heavier hatching on
the large map.

Giaour Kalesi is close to the boundary between the series of
sandstones just described and one of the great plains that make
the type-landscape of central Anatolia. The boundary runs north-
east and southwest, and was followed most of the way from Ham-
mam Merkes to the Hohan Gol. The castle itself, however, is
on a pinnacle of very different rock, more similar to those which
wall the gorge at Arif and also to those at Angora and Assi Yuz-
gad. It may then be of the same period as the surrounding rock,
or with the Angora series, much older. There was no noticeable
continuation of it through the surrounding rolling country. All
the apparently earlier walls of- the castle were built of it. The
stones were small and yet show no great signs of weathering, in
marked contrast to the condition of Boghaz Koi, also built of its
local marble during the same period of history. Less than an hour
east of Giaour Kalesi is the village of Oyaja, built about the base
of two trap necks, like’ a miniature Angora. These, or other
similar outcrops, furnished the material for the later heaviest
walls of Giaour Kalesi.

Looking off from the top of Giaour Kalesi the hills seemed
spotted with deep green, the characteristic mark a little farther
east of the serpentines, and here doubtless due to the same cause.
The spots seemed to have no regular arrangement and perhaps
marked small volcanic necks, which, being soft, did not project
above the general level.

68 WILLIAM T. M. FORBES

THE ANGORA DISTRICT

In the neighborhood of Angora I first came across the confused
mass of rocks that seems to be typical of the igneous areas of Asia
Minor. We stopped some time at Angora, and a day at Ortak6i,
near by, giving rather more opportunity than usual to study
the conditions. The series that leaves the strongest impression
with one is a group of schists, extending roughly northeast and
southwest, alternating between dark schists with hornblende
or mica, sometimes very dense, and a very friable, whitish type,
which seemed to have talc or sericite for its foundation (a snap-
judgment, as there was of course no opportunity to go back).
Neither of these types had the superficial appearance of stratified
rock, but the relation of the two schists to each other and to the
limestone of Elma Dagh convinces me that they were originally
sedimentary. Tchihatcheff calls the whole system serpentine,
and considers it igneous. They were apparently interrupted by
a lava flow from Angora, southeast of the city where Tchihatcheff
crossed the Elma Dagh, but the clay-slates, ‘‘Thonschiefer,’”’ on
the road south from Angora, would seem to belong to the same
bed; at least they have the same relation to the limestone.

I crossed the entire width of the schists, going a few rods north,
and three miles south, from Ortak6i. South of Angora the
Thonschiefer were of about the same width.

The marble was traversed in two places, and was also noted
by Tchihatcheff about half-way between these two, giving a good
idea of it. It seems to form the whole crest of the Elma Dagh
and may extend quite a little farther at each end. Hamilton and
Tchihatcheff’s notes would however seem to indicate that it is
limited by Jurassic sandstones to the southwest, and apparently
to the northeast also before reaching the Kyzyl Yrmak. Might
the coalbeds reported near Kalejik, on the Kyzyl Yrmak, belong
to the same system? To the north the schists were very soon
cut off by igneous rocks of various kinds, but Hamilton reports
both schists and limestones again north of them for some twenty
miles northeast from Angora.

The most typical of the igneous rocks are the necks which
rise in Angora itself. These are of a reddish or purple trachytic

GEOLOGICAL ROUTE THROUGH ASIA MINOR 69

DAMM GERGWYA

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70 WILLIAM T. M. FORBES

porphyry.t The tuff which covers large areas east of the city,
and makes the hill west of it, is made of the same volcanic rock.
North of Ortakoi there isa long outcrop of the same type of rock,
apparently here a lava flow, interbedded between two layers of
late conglomerates, which in their turn have been made up of
the schists, etc., of the region, and also of a fine-grained sandstone
evidently not very old. Over the upper bed is a layer of white
tuff, which one would naturally associate with the trachytes at
Angora, and over this again a flow of very dark trap of indefinite
extent. This trap would seem to make all the mountains to the
north, at least for some distance. ‘There are also dykes of it cutting
all the earlier beds, and necks of it north and northeast of Ortak6i.
There is a small neck of the Angora trachyte also penetrating the
limestone three miles south of Ortak6i.

To sum up, there seem to have been the following periods of
deposit: “(1) the system of limestones and schists which were
probably metamorphosed and eroded before the next period;
(2) the sandstone which formed an element of the conglomerates,
and so must have had time to become consolidated before the
date of the eruptions; (3) the eruptions of Angora trachyte, form-
ing also the white, and porphyry tuffs (during lulls in this the con-
glomerates north of Ortakoi were deposited by the precursor of
the Enguri Su); (4) the period of the dark traps. Since the last
there has been time for the whole lansdcape to be eroded down to
its roots, leaving even the latest volcanic rocks as necks, and flows
which have been tilted to decided angles.

Almost a continuation of the Angora complex is the district
about Kylyjlar. Just north of Assi Yuzgad there is a volcanic
mass, apparently a sheet extending northward. Soon after reach-
ing the hilltop the marbles about Assi Yuzgad, which have domi-
nated since the last watershed west of the town, are in their turn
replaced by an area of dense dark volcanic rock, mostly altered
into serpentine, which extends, with various admixtures, almost

* Bukowski has studied the igneous rocks of this district at some length. He
finds the dominant rocks to be a variety of andesite, with quite a number of other
igneous types, however. So probably the so-called trachyte and trap of the older
geologists of Asia Minor should often be interpreted rather as andesite. He traces
the extent of this igneous area to the north. See the Bibliography.

PLATE I

/ 32° ; S]

a /AFIUN KARA HISSAR
3 ANGORA.

Based on FR. Kiepert’s Karle von
Hleinasien, and Topographic

Notes by Jesse E.Wrench. Geo-
logical otes by W.7.M.Forbes

FOR EXPLANATION OF SYMBOLS SEEAHE
ANGORA-GASAREASHEET,/

EOCENE

Y,
Ye BORDIUM

A
Y,
f

IAS

MOHAN GOL

HAMMAM,
EQCENE @) 3°

Grotocy, Vor. XIX, No. 1

JouRNAL OF

forth of Here.

NE
METAMORPHIC
Lt STONE

METAMORPHIC Y
LIMESTONE rs
/

1 8

(2
regoooe.
2 OPCISGOG.
LAR ER LE ‘3
A

Prare I

JURA, Se ae on oe

TRACHYTE

METAMORPHIC

LIME STONE

SYEMITE

4
MCUs Taine Canaan
\
ee

eH
LACUSTRINE WA

APerbee cal,

4 “AFIUN KARA HSSAR
ANGORA. = /

NS
Based on PR. Kiepert’s Karte von
Aleinasien, ane Topographic
Notes by Jesse &. Wrencd, Geo-
logical Motes by WIM Forbes,
FOR EXPLANATION OF SYMBOLS SEE THE
ANGORA*GAESAREA SHEET,

ROCRNE

OMAN a OL

HAIMA vis
MOCENE 5
Z Rae > 3 39

GEOLOGICAL ROUTE THROUGH ASIA MINOR He

to the Kyzyl Yrmak. For the first couple of miles it is inter-
rupted by several reappearances of the marble. Two of the hills
south, also, are crowned by later horizontal beds. The dominance
of the serpentines gives the whole country as far as one can see a
deep green tint, varying in spots to pale green and to liver-red.
After crossing a broad alluvial plain without outcrops, and then
a narrow ridge of volcanic rock similar to the deposits to the west,
we reach the immediate vicinity of Kylyjlar.

(Up:

Fic. 4.—Index map of Asia Minor.

On the east slope of the last ridge west of Kylyjlar, there is a
small outcrop of schist, dipping steeply to the northwest, and
similar to that east of Angora. Underlying it is a small patch of
syenite, not indicated on the map, and east of that again a flat-
topped hill that dominates the whole valley. This hill seems
to be formed of the serpentines, but is capped with a layer of the
gray and white Angora limestone, apparently originally continu-
ous with the beds east of the valley. East of Kylyjlar the domi-~
nant rock is still the same serpentine, but with the denser type
less common, and more mixed than before with the greenish white
tuffs (?). For a mile immediately east of the town, however, it

72 WILLIAM T. M. FORBES

is clearly a tuff with large pieces of the dense volcanic rock as a
foundation.

Interbedded with this tuff there comes in quick succession a
series all dipping northeast: in order going eastward, conglomerate,
Angora limestone, tuff, limestone, tuff again. There is also a very
conspicuous line of the pale-green rock running south behind Kyly-
jlar, parallel to the valley. I did not find its contact with the
stratified rocks, possibly a dyke of some kind. The marble appears
in several other places between this district and the Kyzyl Yrmak,
and also (but here the white crystalline type we found about
Assi Yuzgad) in a prominent hill just across the Kyzyl Yrmak.

Two miles east of Kylyjlar the serpentines east of the path are
replaced by syenite, but they continue south of the syenite, and
underlie the Neocene rocks for a distance farther. On leaving
the syenites, now only a long mile from the river, we ourselves
strike into the Neocene deposits that fill the bed of the river and
extend indefinitely eastward. The neocenes are an alternation
of conglomerate, sandstone, and a fine-grained rock: like pale-
brown sugar (perhaps the “‘saccharine limestone” of Tchihatcheff).
The latter is well exposed immediately around Yakshy Khan and
seems to be the top layer of the series.

THE SUNGURLU SERIES

The section between the Kyzyl Yrmak and the Delidjé Yrmak
is dominated by Eocene deposits. However, here and there igneous
masses were seen, and they were probably numerous off of our
route. Apparently serpentines form considerable outcrops south
of Yakshy Khan, along the west bank of the Kyzyl Yrmak,
and about a third way to Izz-ed-Din it again becomes probable
that the distant rocks to the south are serpentines. An hour
northeast of this last deposit there is a very conspicuous outcrop
of syenite, cut from east to west by a crooked gorge which serves
asaroad. Immediately north of Yaghly there is evidently another
‘igneous outcrop abruptly cut off to the south by a small brook,
in a way that suggests the possibility of a fault running northwest
and southeast.

East of this line, almost as far as Eyiik, and from there south

JoURNAL oF GEOLOGY,

Eocene

PLATE II

Dn6esGog
SANSA
i LOCEOOM

36°

| en ANGORA*C/ESAREA

Based on R. Kiepert's "Harte yon
Kleinasien," ana Topographic
Noles by Jesse FE Wrench. Geo- 39
logical Notes by W.T.M Forbes.

TRACHYTE

EOCENE ie

DOLERITE
LACUS TRI(NE

Ba Ie f
ACA SAREA,

TRACHYTE

Journat or GroLocy, Vor. XIX, No. 1 Prare IT

40° os" a - j
ANGORA*CASAREA
Based on R.Kiepert’s “Karte yon
e€inasien,” ana Topo Aa
Notes by Jesse & Wranenaigees
logical Notes by W.T.M Forbes.

36*

METAMORP WIC
LimesTgne

GRANITE A.
SERPENTINE a Wh

DIORITE

OIORITE LACUSTRINE

/
Vi JS
y a,
}
,
\
NS METAMORPHIC TRACHYTE
y, LIMESTONE
Vy, ~

\ BQCENE
EOCENE ete,

/ DOLERITE

TRACHYTE, NS / LACUSTRINE

ME)\DIE re SG : YO
TX CASAREA,
Ws

EOCENE

EXPLANATION ¢ SYMBOLS
Superficial Deposits.

Neoce nes.
Wor/zontally Bedded).

=
(UM) Zt

| Metamorphic Limestones

Asst Yurgad type
of Limestones.

Schists. KARABURUN

Toachy lesyard Similar Up A
lgneédus Rocks. Y psi
ZG

Mixture of lgneous Racks,
Tiffs,and Facene ana
Neocene Deposits.

A Mesozoic and Eocene
LL) Deposits (Mastly cal-

careous sandstones 5 ui
with steep dips) lerpentine.

NJ fossiliferous Strata . ;
NG of thesame typo. Co Undetermined Deposits
2 -~-. Author's Route. .

Ne IN THIS STYLE OF LETTER Deposits Noted by other Authors.

IN THIS STYLE OF LETTER Jdontified Fossils farous Strata.

Syenite ana Granite

Je TRACHYTE

LAcus TRINE
ROCENE

MINA tal,

GEOLOGICAL ROUTE THROUGH ASIA MINOR 73

to Yuzgad, rocks of Eocene facies were constantly in sight, the
immediate vicinity of Boghaz K6i making the only serious inter-
ruption. In the immediate vicinity of Aktché K6yiin our route
took us out of this Eocene area into the lacustrine plain which so
often accompanies the larger rivers of Anatolia.

The rocks of Eocene facies dip at various angles, and do not
seem to be entirely conformable. However, as in unquestionably
conformable series in that vicinity the dips and strikes often
change very abruptly, I should not dare to say that more than one
period is represented. One may take, for instance, the case
sketched here. This is a frontal view of a bluff, past which the

Fic. 5.—Frontal view of a bluff a short distance east of Alembeyli, showing very
rapid change in dip of the strata. The stippled layers represent gypsum; the rest is
sandstone. The road passes through the right-hand depression. (Somewhat dia-
grammatic.)

road ran (through the central gap, in fact). The entire part of
the ridge shown in the figure was but a few rods long, and as one
can see, the dip of the strata has changed considerably. Actually
aside from this anticlinal structure the whole series dipped away
moderately. At this particular point, near Alembeyli, there was
some tendency for the dips to be moderate and easterly. South-
west of Aktché K6yiin the dips of the nearer strata were about
the same, but some strata were seen dipping at angles of over 45°.
As already mentioned the two sets appeared unconformable but
this may have been because of inability to see the intermediate
rocks.

At Sungurlu, at the east end of the village, there is a thin bed
of plant remains, but they proved too fragile for transport.

BOGHAZ KOI
The dominant rock at Boghaz KGi is a marble breccia, with a

bright red cementing material, making a striking pattern. Occa-
sionally the marble is more massive, and then may appear either

74 WILLIAM T. M. FORBES

like the Angora or the Assi Yuzgad types, showing that the latter
two can well be of the same date.

_ Mixed all through with these marbles is a serpentine, in which,
wherever the outcrops are clear, the marble appears to be floating

Serpentine
RQY PateGreen S.
ATA Tuff
Morble
\w Sandstone
EE} Neocene.

Ke Ne Route
KYO ORR AR RRA, SELES : ——- Other Roads

iy
KK
‘ZB
iY,
is

: best) >
YAR?
Ze, ZA

Fic. 6

in large blocks. The serpentine is less in evidence immediately
under the ruins at Boghaz K@i, but even there the excavations
have exposed it enough to suggest that the arrangement is the
same.

At the point where the dominant limestones give way to ser-
pentines, as one goes south from the village and the ruins, there «is
an east-and-west bed of a dense siliceous rock that also appears

GEOLOGICAL ROUTE THROUGH ASIA MINOR 75

a second time farther south, interbedded with sandstones. In
both cases the dip is northeast.

Farther east and up the main valley as far north as Devret the
rocks and their arrangement are different. Here there are two
bands of a dark tuff, with fragments of vesicular trap, imbedded
in sandstone, and the whole dipping to the east. Where we went,

Emirler.

Fic. 7.—Sketch of a small area near Emirler, just north of Boghaz K6i, showing
the relation between limestone and serpentine usual in that district. The hatched
areas are limestone; the remainder is probably mostly or entirely serpentine, but
largely covered up. :

as shown on the map, it seems to disappear within a short distance
under the serpentines. But it probably extends farther to the
southeast and east, through the area left white on the map.
North-northeast of Boghaz Koi, the mixture of serpentine and
marble continues half-way to Eyiik, the serpentine dominating
for the southern half and disappearing in the northern half. About
at the point where the serpentine ceases to appear in any quantity
there are several outcrops of denser igneous rocks. The space
immediately south of Eyiik is occupied by fine-grained Neocene
limestones, containing plant remains in poor condition. A little

76 WILLIAM T. M. FORBES

farther west, and more directly north of Boghaz KGi, there is no
sign of the limestone or serpentine, but the Eocene (?) rocks which
extend west to Yaghly take their place.

THE YUZGAD COMPLEX

Five or six miles south of Boghaz K6i the serpentines and
limestones again make way for the rocks of Eocene facies, but now
they are much interrupted by igneous rocks in great variety.
Our road, the new chaussée, ran at first southeast, over the divide.
Then we entered the valley of a large stream which flows off to the
southwest and is followed by the old chaussée. We went upstream
(to the east) for a couple of miles along one of its tributaries, after
coming down from the divide along another; and then we turned
abruptly southeast to cross the very top of Kabak Tepé, the moun-
tain just north of Yuzgad, by a very complex system of zigzags.
From the height of land till we left the main valley to climb Kabak
Tepé, and actually till we were fairly up on the slopes of Kabak
Tepé, the supposed eocenes make up the mass of the rock. South-
west of the road about a mile south of the divide there could be
seen a flat mesa which has been used for ‘‘cliff-dwellings.”’ It is
probably a tuff or soft trap like the beds so used elsewhere, and
made a distinctly incongruous note among the other rocks of the
district. In any case it is Neocene in date, and unconformable on
the local bedrock. Northeast of the road in the same neighbor-
hood there are several appearances of granite (probably more
nearly of the date of the bedrock). At the point of forking of the
old and new chaussées, where the road ceases to go south down
one tributary and turns east up the other, there are a couple of
trap dykes, both small, but perhaps outliers from more extensive
intrusions to the north.

A couple of miles south of the valley of the tributary running
from east to west the supposed eocenes either disappear or else
change their character entirely under the influence of the many
igneous rocks, which now become dominant. Of this district one
can only say that it is a practically inextricable tangle. It is com-
posed, among other rocks, of granites, dark traps, schists, frag-
ments of Eocene beds (some containing fossils according to Tchi-

GEOLOGICAL ROUTE THROUGH ASIA MINOR Te

hatcheff), tuffs, and Neocene sandstones and conglomerates. Im-
mediately about the town there are several outcrops of tuff.

Hamilton and Tchihatcheff report the same types as making
the entire region west to near the Delidjé Yrmak, and northeast
for an equal distance. To the southwest, however, after about
ten miles they gradually give place to neocenes, which extend in
the main to Hadji Bektash. Tchihatcheff discusses this complex
with the dolerites.

Getchi Kalesi, the mountain to the east of Medjidié, in the
northern part of the Malya Tchol, is only the culminating point
in a limestone range, cored with trap, which extends from west
of Medjidié southeast for a dozen miles. The limestones at several
points contain Eocene nummulites in quantity. At the point
where the road traverses this series, south of Medjidié, the eocenes
are not conspicuous, and the traps are locally interrupted, but
behind the city, the traps stand up in a series of prominent and
ragged hills. Even here I have a feeling that the igneous dyke
is not entirely continuous. A little farther south, and on the other
side of the path, the igneous rocks appear again in a couple of
amorphous masses (as seen from a distance), the eocenes remain-
ing inconspicuous, but Getchi Kalesi itself is of a somewhat differ-
ent structure. The dyke here seems to be fairly continuous, and
in general makes the crest of the ridge. Leaning against the west
side of this is a long series of Eocene limestones, etc., all with dips
of about 60° to the north. Apparently on the east side of the
dyke the same facing occurs, and the very highest point of all is
formed by one of these strata which is continuous across the top
of the dyke. This very topmost point furnished one of my num-
mulite specimens, through the kindness of Mr. Wrench.

A little farther south the village of Mahmatly is situated in a
very striking gorge, which marks the boundary between a lower
and a higher level of the Malya Tchél. On the steep sides of this
gorge, as well as the escarpments that lead up to its mouth, the
neocenes are interrupted, laying bare the substratum of the
Tchél, which is evidently of the same system as Getchi Kalesi
mountain. Half a day’s journey farther south there is a long hill
a moderate distance west of the road, which again shows the

78 WILLIAM T. M. FORBES

steeply dipping strata of the Eocene series. At one place Num-
mulites levigata (Lutétien period of the Eocene) was picked up,
but not 7m situ.

2
e,

O
<<
<
o<

= <=
vehi 3
yr Castle §&

Oe
<
SSS
KKK

—
Sx
SS

an
es

Fic. 8.—Kara Burun and immediate vicinity. The trap is indicated by hori-
zontal lines, the granite by coarse cross-hatching. Gardens have been shown in
stipple, indicating the position of springs.

There are also some smaller igneous outcrops in the neighbor-
hood of Medjidié, which do not seem to belong to the Getchi
Kalesi range, in particular a neck of very coarse porphyry some
five miles northeast of that town and on the other side of the river.

GEOLOGICAL ROUTE THROUGH ASIA MINOR 79

The district between the Malya Tchél and the Kyzyl Yrmak
valley to the south is again apparently eocene in date, resembling
closely in appearance the Haimané and the vicinity of Sungurlu.
The very top of the divide south of Hadji Bektash showed no out-
crops, but the pebbles brought down and the appearance of the
distant hills would imply that it also had a volcanic core. It isa
very much more insignificant ridge than Kiepert’s map would
. suggest.

KARA BURUN

The village of Kara Burun is located on the east slope of a mesa
capped with a sheet of hard black trap. This sheet disappears
abruptly at the north end of the village against a steep bluff of
much-rotted granite, which in its turn is capped with a second
sheet of trap exactly similar to the first, but on a higher level.
The lower level trap, like the upper, seems underlaid with granite.

Kast of the upper level, the granite is laid bare in several places,
but east of the lower level there are no near outcrops. On the
south boundary of the granite outcrop there is a line of springs
marked by gardens and villages, of which the first is Kara Burun
itself. The whole, with the line between the upper and the lower
Kara Burun traps and the southern boundary of the Eocene deposits
farther to the east, forms a line nearly parallel to the Kyzyl Yrmak
river which I have interpreted as possibly a fault.

East of Kara Burun the Kyzyl Yrmak valley, as far at least as
Avanos, is filled with a series of almost horizontally bedded neo-
cenes, more or less tufaceous, which gradually rise as one goes east.
They are cut off to the south by the valley of the river, and seem
on the north to end abruptly against the eocenes. Farther to the
east, as one approaches Avanos, the eocenes appear from below
and the later deposits make only a narrow cornice against the bluff.
Some of this series of beds are more or less water-worn conglomer-
ates, while others are fine-grained tuffs of very even texture. The
latter especially have been much used by the troglodytes for
excavating houses, churches, and tombs.

South of the river one can see a great confusion of lava-sheets,
the spaces between which are taken up by vast masses of tuff.
Occasionally the tufaceous matter would become less noticeable,

80 WILLIAM T. M. FORBES

and they would grade into the usual Neocene conglomerates. The
trap-sheets hardly appear north of the river, except at Kara Burun.

Several miles west of Inje Su there is a perfectly flat plain,
formed by the vesicular surface of one of the trap-sheets. Nearer
to Inje Su itself a stream has cut a deep gorge in this bed, exposing
the underlying tuff.

The district between Avanos and Inje Su is the famous troglo-
dyte country, which also extends a long distance to the south, to
the west of Mount Argaeus. In the neighborhood of Urgiib there
had evidently been at one time a thick layer of fine homogeneous
tuff, capped with a thin trap-sheet, which though harder than the
tuff was itself easily weathered and cracked into blocks. Erosion
has cut this whole district into a mass of cones of tuff, the higher
ones of which are still capped with small blocks of trap. Between
these higher ones there are a vast number of shorter cones, whose
lava caps have fallen off, and which are fast being eroded away.
When the cap falls off it sometimes finds new lodgment at a lower
level, and becomes the nucleus of a new shorter cone. Hundreds
of the cones have been used by the troglodytes for excavating
houses, and many of these are still in use. Where the country is
at a little higher level, at Urgiib village, the country is not broken
up into separate cones, but there is a large mass of tuff, crowned
by a continuous sheet, and terminated to the north with a con-
tinuous cliff. The village was originally a system of troglodyte
houses excavated in the face of this cliff, but most of the houses
have added built facades in more recent times. It is still distinctly
a troglodyte village nevertheless.

Beyond Inje Su notes were not taken, but the general character
of the country does not change. Tchihatcheff spent considerable
time in this district, and gives a long and interesting account of it
in the section ‘‘trachytes”’ of his geology of Asia Minor.

THE LACUSTRINES

In this survey I have passed over several sections of the route
with hardly a word. These are occupied by the characteristic
Neocene (lacustrine) deposits which seem to cover nearly half the
surface of Anatolia. They are in general horizontally bedded or

GEOLOGICAL ROUTE THROUGH ASIA MINOR SI

nearly so, sometimes fossiliferous—then generally Pliocene—often
formed of the same materials as the eocenes of their district.
Still more often they show a more or less characteristic appear-
ance, and may usually be distinguished by their horizontal bedding.

In every place where they come in contact with the trachyte
(andesite) deposits, they grade into their tuffs, and are evidently
in a general way of the same period. This shows conspicuously at
Yuzgad and along the Kyzyl Yrmak near Caesarea.

Here is a list of the places where I found deposits of this type
to predominate:

The Sakaria valley near Aktash, and from there to Sivri Hissar.

The Sakaria valley from Sivri Hissar east to the river at Gordium.

The country east of Hammam Merkes and Giaour Kalesi.

The Kyzyl Yrmak valley from Yakshy Khan to Yaghly.

The region about Eyiik.

The region beginning just south of Yuzgad and extending the entire length
of the Malya Tchol almost to Hadji Bektash.

BIBLIOGRAPHY

Congres géologique internationale. Compte rendu de la [X® session, Vienne,
1903. This contains two important papers on the Bibliography of Asia
Minor, so complete that it seems unnecessary to give a detailed bibliography
here. These are:

Touta, Franz. Der gegenwirtige Stand der geologischen Erforschung der
Balkan-Halbinsel und des Orients, p. 175; followed by—

Touta, Franz. Ubersicht iiber die geologische Literatur der Balkanhalbinsel
mit Morea, des Archipels mit Creta und Cypern, der Halbinsel Anatolien,
Syrien und Paliastinas, pp. 185 to 330. This is a bibliography of over 1,300
titles, arranged chronologically.

von Bukowski. GerjzA: Neuere Fortschritte in der Kenntnis der Strati-
graphie von Kleinasien. Loc. cit., p. 393. A bibliography arranged by
authors.

Hamitton, WILLIAM JOHN. Researches in Asia Minor. 2 vols. London, 1842.
A book of travels with frequent geological notes. The geological part, as
well as that of the other older authors, has been summarized by Tchihatcheff,
and harmonized with his own observations. |

TCHIHATCHEFF, PAuL DE. Asie Mineure. Paris, 1866 to 1869. Paléontologie
by A. d’Archiac, P. Fischer, and E. de Verneuil, in one vol., with atlas.

Asie Mineure. Géologie, in 3 vols., with a geological map of Asia

Minor, and one of the Bosporus. The classic.

Asie Mineure. There are numerous other papers by Tchihatcheff,

for which one may consult the bibliographies cited above.

82 WILLIAM T. M. FORBES

SCHAFFER, F. Cilicia. In Petermanns Mittheilungen, Erganzungsheft 141, 1903.
It contains a geological map of Cilicia and the neighboring district, which
adjoins the route of our studies on the south.

LAPPARENT, A. DE. ‘Traité de géologie. Ve. édition, 1906. Summarizes
the stratigraphical knowledge of Asia Minor along with the rest of the
world.

Lronuarp, R. Geologische Skizze des galatischen Andesitgebiets nordlich von
Angora. Neues Jahrbuch fiir Mineralogie, etc. Beilageband XVI, 99 to
109, with a sketch map.

p’Arcutac, A AND J. Hamme. Description des animaux fossiles du groupe num-
mulitique de l’Inde, precédée d’un résumé géologique et d’une monographie
des nummulites. Paris, 1853. A useful reference book on the nummulites.

Witson, Str CHARLES. Handbook for travelers in Asia Minor, Transcaucasia,
Persia, etc. (Murray’s Handbook). The most convenient book for
geographic information.

Kierert, RicHArD. Karte von Kleinasien. 1:400,000. Berlin, published in
sheets. The standard map of the country.

THE VARIATIONS OF GLACIERS. XV"

HARRY FIELDING REID
Johns Hopkins University

The following is a summary of the Fourteenth Annual Report
of the International Committee on Glaciers.”

REPORT OF GLACIERS FOR 1908

Swiss Alps.—Of the ninety glaciers which were measured in
1908, fifty-three are in undoubted or probable retreat, one is
certainly advancing, and thirteen are possibly advancing. The
retreat, therefore, is general. Certain small glaciers have for
some years shown signs, more or less definite, of advance. Short
glaciers respond more quickly than long ones to the changes in
snow-fall, and may make a number of small variations which are
not indicated by large glaciers.’

Eastern Alps.—A large part of the observations on the glaciers
of the Eastern Alps were carried out under the auspices and at
the expense of the German and Austrian Alpine Club.

The general retreat was dominant between 1907 and 1908, as it
has been for several years past. Only a single glacier, the Wansee-
ferner, in the Oztetal, has advanced; its advance amounted to 15
meters. The other glaciers showed retreats amounting in some
cases tO 22, meters:?

Italian Alps.—The observations of the Italian glaciers were all
the results of private enterprise. All the glaciers observed on the
south side of the Alps were apparently in retreat, except possibly
a few in the Maritime Alps, which, seen from a distance, had appar-
ently enlarged slightly; but this observation is doubtful.s

French Alps.—Many observations on the snow-fall and varia-

t The earlier reports appeared in the Journal of Geology, Vols. III-XVII.

2 Zeitschrift fiir Gletscherkunde (1910), IV, 161-76.

. 3 Report of Professor Forel and M. Muret.

4 Report of Professor Briickner.
5 Report of Professor Marinelli.

84 HARRY FIELDING REID

tions of glaciers were made under the direction of the Minister of
Agriculture.

During the winter of 1907-8, the amount of snow-fall was regis-
tered in twenty-seven stations in Savoy; although the snow-fall
was less than in the previous year, still the total amount was fairly
large. The maximum does not increase with the altitude, as the
altitude becomes high; but the observations along this line are
still incomplete.

On Mont Blanc the Glacier de Bionnassay, which between 1906 and
1907 had advanced 38 meters, in 1907-8 advanced 17.5 meters farther.
The three other glaciers observed in this region had all retreated.’
The retreat of the Glacier du Tour amounted to 52.5 meters. In
the Maurienne three small contiguous glaciers made a slight ad-
vance; a fourth glacier, not far distant, had retreated markedly."

Pyrenees.—A number of glaciers observed in this region showed
a tendency to a slight advance.’

Swedish Alps—The retreat of the glaciers of Lapland, noticed
since 1900, has been confirmed. During the summer of 1908 sig-
nals were placed near many glaciers which will lead to more definite
results in the future.

Norwegian Alps.—The glaciers of the Jotenheim are in marked
retreat, whereas those of the Jostedal and Folgenfon, nearer the
coast, show an equally marked advance, the variations between
1907 and 1908 amounting in some cases to about 30 meters.’

Canada.—The [Illecillewaet Glacier retreated about 4o feet
between 1907 and 1908.3

Himalaya.—Although no new observations have been made,
there are indications that since the survey of 1872-75 the glaciers
of Garhwal and Kashmir have retreated considerably.!

REPORT OF THE GLACIERS OF THE UNITED STATES FOR 1909°

Hallett Glacier, Colorado, shows no change between 1908 and
tgo09 (Mills).

™ Report of M. Rabot. 3 Report of Mr. Vaux.
2 Report of M. Oyen. 4 Report of Mr. Freshfield.

5 A synopsis of this report will appear in the Fifteenth Annual Report of the Inter-
national Committee. The report on the glaciers of the United States for the year
1908 was given in this Journal (XVII, No. 7, pp. 667-71).

THE VARIATIONS OF GLACIERS 85

The glaciers of Mt. Hood, Oregon, show a marked recession
since 1906 and they have also decreased in thickness. The White
Glacier has receded about 400 meters; Sandy Glacier 100 to 200
meters; Reid Glacier 50 to 100 meters, and Zig-Zag is hardly
more than an ice-bank. The glaciers on the north side of the
mountain, as seen from the summit, also seemed reduced in size
(Montgomery).

Lyman Glacier, near Lake Chelan in central Washington, is
still diminishing (Rusk).

Mt. Baker, Washington, the most northerly of the great vol-
canic cones which rise above the Cascade Range, was surveyed
during the summer of 1909 by the United Stated Geological Sur-
vey, the party being under the direction of Mr. J. E. Blackburn.
Mt. Baker, 10,745 feet high, is covered with ice and snow above an
altitude-of 5,000 feet, divided into a few separate masses by narrow
ridges of rock.

At the lower levels glacier tongues develop, some of which
extend to as low an altitude as 3,500 feet. Seven glaciers have
been given names, the Roosevelt, Mazama, Wells Creek, Sholes,
Park, Boulder Creek, and Nooksack. The last has not been
fully explored and may later be divided and receive several names.
The ice of these glaciers is especially broken up by large and numer-
ous crevasses. The crater of the mountain, from which steam is
still escaping, is about 1,000 feet below the flat snow-covered sum-
mit. The moraines in front of the glaciers’ ends and the polished
and grooved rock along their sides show clearly that they are
retreating and d:minishing in volume.

Fifteen miles northeast of Mt. Baker rises the spire of Mt.
Shuksan, 9,038 feet; a glacier on ‘ts wes:ern side breaks over a
cliff and the ice collects to form a reconstructed glacier at a lower
level; this glacier then falls over a second cliff and forms a second
reconstructed glacier still lower down (Blackburn).

The United States Coast and Geodetic Survey has published a
map of Glacier Bay, and the surrounding area, on a scale of 1/160,-
ooo, from surveys made in 1907.’ It is interesting to compare this
map with the earlier one published by the survey in 1899.2, The

t Tt is numbered 8306 and was published in January, rgro.

2 No. 3095.

86 HARRY FIELDING REID

latter was based on surveys made by Reid in 1892, with additions
taken from the surveys of the United States Coast and Geodetic
Survey and of the Canadian Boundary Commission between 1884
and 1895. At the first glance one is struck by the smaller area
covered by the ice, and the correspondingly greater area of bare
rock; for instance, the ridge between Casement and McBride
glaciers was broken in the earlier map by many arms of ice con-
necting the two glaciers; the later map shows this ridge as
continuous and much broadened. Similar changes are noted in
other parts of the map. This indicates not merely the melting
of small connecting arms of ice, but also a general lowering of
the whole surface of the ice. Dying Glacier at the head of Tidal
Inlet has entirely disappeared, and Dirt Glacier, immediately east
of Muir Inlet, is not represented on the later map. I am inclined
to think that this glacier has not completely melted, but that its
very thick covering of moraine has masked its character. Large
areas of rock are free of the ice which covered them in 1892.

The ends of the tide-water glaciers have receded greatly (as
noted in earlier reports of this series) and allowed the inlets to
penetrate farther into the land.

The end of Muir Glacier has receded and divided into two
parts, separated by the rocky island which appeared as two dis-
tinct nunataks in 1892 about 3 miles from the ice-front. To the
north the glacier has receded 8.5 miles. The ice surrounds the
water on three sides; bergs are discharged most actively at the
northern end of the inlet. To the east the glacier has receded
3 miles and ends in a sloping surface just reaching- the water.
(Since 1907 this portion has receded still farther and now rests
on a sandy beach, where it is forming a terminal moraine
Dunann.)

The total increase in the area of the inlet between 1892 and
1907 was Ig square miles.

Carroll Glacier does not seem to have receded, but the Rendu
has retreated about half a mile. Grand Pacific Glacier has receded
73 miles, almost as much as the Muir, and its inlet has increased
by 14 square miles. Johns Hopkins has receded 3 miles, increasing
its inlet by 55 square miles, and separating from one of its southern

THE VARIATIONS OF GLACIERS 87

tributaries, which becomes an independent tide-water glacier.
Reid Glacier seems to have receded about 3 mile.

In 1892 Hugh Miller Glacier attained tide-level at two termini;
one, on the north, barely reached the water and had a sloping
surface; this has retreated about half a mile. The other terminus,
on the east, was divided by a rocky mass, north of which the ice re-
sembled the northern terminus but south of which it ended in a cliff
discharging bergs. ‘The northern part of this terminus has receded
about one mile and has uncovered much rock, about 1% square
miles; the southern part has receded about 13 miles and the inlet
has increased by about 2 square miles. Charpentier Glacier has
receded about 13 miles and its inlet has increased by one square
mile. Geikie Glacier has receded about ? mile and Wood Glacier
has greatly diminished in size, though it still seems to reach tide-
water as in 1892 without an ice cliff. The total increase in the
area of Glacier Bay, as the result of the recession of the glaciers,
amounts to about 50 square miles.

Professor Ralph S. Tarr has published a detailed account of
the Yakutat Bay Glaciers, with many illustrations and maps,
which includes all information regarding these glaciers available
at the end of 1906.1. The remarkable advance of some of these
glaciers in the interval between Professor Tarr’s visits to them in
1905 and 1906 are carefully considered and ascribed to extraordi-
nary supplies of snow shaken down from the mountains by earth-
quakes in 1899.2 This very excellent monograph can receive only
a cursory notice here. Professors Tarr and Lawrence Martin
organized an expedition under the auspices of the National Geo-
graphic Society to revisit Yakutat Bay and Prince William Sound
in 1909. Professor Martin has sent me the following outlines of
the results of this expedition:

The National Geographic Society’s Alaskan Expedition of 1909 in charge
of R. S. Tarr and Lawrence Martin observed the following variations of
glaciers.

In Yakutat Bay Hubbard Glacier seemed to be beginning to advance more

™“The Yakutat Bay Region, Alaska,” U.S. Geological Survey, Professional
Paper No. 64, Washington, 1909.
2 Mentioned in an earlier report of this series (this Journal [1908], XVI, 54-55).

88 HARRY FIELDING REID

rapidly; Lucia Glacier was advancing rapidly and overriding a nunatak after
semi-stagnation since before 1890; Hidden Glacier had advanced 3 kms. in
less than 3 years and had returned to semi-stagnation; Nunatak Glacier
was continuing the retreat in progress since 1890, having retreated over {
km. since 1906 or nearly 53 kms. since 1895; Turner Glacier had advanced
slightly since 1906. The Variegated, Haenke, Atrevida, and the Marvine
lobe of Malaspina Glacier had ceased the spasmodic advance which Tarr
observed in 1906 and explained, not as climatic, but as part of a glacier flood
due to earthquake avalanching. Haenke Glacier, which advanced and became
tidal between September, 1905 and June, 1906, had retreated before 1909 so
that it no longer discharged icebergs, being fronted by a low gravel cliff. It
was once more mantled with ablation moraine, as were large parts of Varie-
gated and Atrevida glaciers and the Marvine lobe of Malaspina Glacier.
Our party easily crossed Variegated and Atrevida Glaciers in 1909 in the parts
most impassably crevassed in 1906. The advance of three additional glaciers
between 1906 and 1909 and the quick return to semi-stagnation in 1909 of
the four that were rapidly advancing in 1906 gives additional proof of the
earthquake-avalanche hypothesis for certain variations of mountain glaciers.

On the lower Copper River the Miles, Childs, and Baird glaciers were,
in r90g, in about the same conditions as when they were seen by Abercrombie
in 1884, by Allen in 1885, by Hayes in 1891, and by Schrader in 1900. Parts
of Miles and Baird glaciers have been stagnant and forest-covered for at least
twenty-five years. Five miles of railway track has been laid on Baird Glacier.
Childs Glacier seems to be advancing and forcing Copper River eastward,
according to Johnson. The rate of movement near its northern margin in
July, 1909 was about 4 feet a day. During the last half of July, 1900, abla-
tion lowered the surface of Childs Glacier at the rate of 7 inches a day.

In eastern Prince William Sound, Valdez Glacier is retreating, as it has
been since 1898 excepting the slight advance between 1905 and 1908 recorded
by Grant. Shoup Glacier has been retreating since 1898 except for a slight
advance, perhaps, in the spring of 1909. Columbia Glacier was continuing
the advance observed by Grant in 1908 and early in July, 1909. The eastern
margin had advanced, before August, 1909, making a decided lobation, but
not reaching the forest along the whole margin. The western margin had
advanced more than 800 feet up to the forest of Gilbert’s maximum of 1892,
as was also the case at Heather Island where the middle of the glacier was
destroying the forest in August, 1909.

The United States Geological Survey has published a bulle-
tin’ containing a short account of the glaciers of the Wrangell

«F, H. Moffit and Adolph Knopf, ‘‘The Mineral Resources of the Nabesna-
White River District, Alaska, with a Section on the Quaternary by S. R. Capps,”
U.S. Geol. Survey, Bull. No. 417, Washington, 1910.

THE VARIATIONS OF GLACIERS 89

Mountains, Alaska, and a topographic map of the region; and
from it we draw the following information:

A very important feature of the Wrangell Mountains is the great ice cap
‘that occupies the crest of the range and that has its greatest development in
the region around Mount Wrangell. From the periphery of this great feed-
ing- ground valley glaciers extend in all directions down the more important
drainage lines.

The Nabesna and the Chisana are by far the largest of these
glaciers. The former is about 55 miles long and has an area of
about 400 square miles. The latter is 30 miles long with an area
of 135 square miles. There are many smaller ice tongues, and
even small glaciers independent of the main ice cap.

The St. Elias Mountains, south of White River, are snow-capped in much
the same way as the Wrangell Mountains. Most of the mountain range is
unexplored, however, and the extent and area of the ice field is unknown.
All the more important tributary valleys to the north are occupied by valley
glaciers, the largest and best known of which is the Russell Glacier, at the head
of White River. The main lobe of ice in the head of the White Valley is
between 6 and 7 miles long and about 23 miles wide, and most of the ice moves

in a northeast direction. A small crescentic lobe, however, moves westward
into the head of Skolai Creek.

Formerly the glaciation was much more extensive, but very
little information is available to determine what changes are
taking place at present. In 1891 the western terminus of Russell
Glacier was a smooth slope, but in 1909 it was a wall of ice from
25 to 75 feet high. This certainly indicates an advance of the
ice, but at the northeastern terminus the ice passes into the moraine
without a clear line of demarkation, indicating a slow, gradual
retreat. The Nizana Glacier was formerly crossed by prospectors
going to the White River region, but it has become so crevassed
as to be practically impassable, which suggests an- advance of
the ice.

REVIEWS

Testing for Metallurgical Processes. By James A. Barr. San
Francisco: The Mining and Scientific Press; London: The
Mining Magazine, 1910. Pp. 216. $2.00 delivered.

This book, which is based on a course of lectures given by Mr. Barr
at the Michigan College of Mines, is a laboratory manual for the student
of metallurgy and for the mining engineer. The treatment differs from
that of the textbooks on metallurgy in that the methods for testing are
fully treated and minute details for many of the operations are given.
It is designed not to take the place of the textbooks on metallurgy but
to supplement them. The subjects treated include amalgamation,
chlorination, cyaniding, concentration, smelting, calculation of lead
and copper slags, cost data, etc. The treatment, while condensed,
is exceptionally clear. The work should be appreciated by students,
mining chemists, and engineers. W. H. E.

Economic Theory with Special Reference to the United States. By
HerinricH Ries. 3d ed. New York: Macmillan, 1910. Pp.
589.

The third edition of this work is revised and greatly amplified.
The treatment of the non-metallic minerals, which covers about 300
pages, is well arranged, and the data are clearly presented. The coal
fields of the United States are described in considerable detail and the
occurrences of other hydrocarbons are mentioned or briefly described.
Chapters are devoted to building stones, clays, limes and cements,
salines, gypsum, fertilizers, abrasives, minor non-metallic minerals, and
underground waters. The illustrations and text figures are well chosen
and clearly executed. The references are numerous, but are placed at
the end of each chapter, a practice which, though saving space, renders
them less accessible to the reader or student. The treatment of the
metals is superior to that of previous editions. Although the book is
intended primarily as a text, it should serve a useful purpose as a work
of reference to the engineer or geologist who wishes general information
regarding the occurrence and uses of certain minerals and the literature
of the subject. W. Hz. E.

REVIEWS QI

The Geology of New Zealand. By JAMES PARK, Professor of
Mining and Mining Geology in the University of Otago. Pp.
488, with 145 illustrations, 27 plates, and a colored geological
map. London: Whitcombe & Tombs, Limited, 1910.

This new work is welcome to the geologic reader because it gives
in organized, systematic, and relatively brief form a general view of
the geology of a country whose geologic literature is otherwise scattered
and to most geologists not readily accessible. It must also be acceptable
to the teachers and students of New Zealand in that it gives them a
view of geological history founded on the formational record of their
own land. The work combines some of the features of a synoptic
governmental report with those of a textbook. It was written originally
for the Department of Mines, but only a part of it was published by
the government—a fact which probably accounts for a seemingly dis-
proportionate treatment of certain topics as compared with others, and
also some lack of continuous progression under the control of a well-
chosen scheme.

Detailed descriptions of the various formations comprise the first
portion of the work. Fach series is discussed first under the head of
distribution, thickness, and age; then the faunas and floras are taken
up, followed by the economic minerals and the igneous activity of the
time. As might not unnaturally be expected in a country where even
today the glaciers are such splendid spectacles, the Glacial Period has
received much fuller treatment proportionately than the other periods.
In an interesting discussion upon the excavating power of glaciers, the
assertion is made that it is certain that ice can only excavate its bed
when the pressure of its mass exceeds the ultimate crushing strength of
the bed rock, and that the pigmy valley glaciers of today are incapable
of excavating their beds. That glaciérs, even those of the small valley
types, may be active eroding agents seems to find much less favor with
the English school of geologists than with the American.

The last portion of the book is devoted to economic geology. Natu-
rally the greatest emphasis and fullest treatment are given to the very
extensive coal fields and the important gold deposits, both of which have
long attracted notice.

A very welcome feature of the book is the closing chapter, which
presents a complete bibliography of the geology of New Zealand cover-
ing 56 pages. This book places the principal facts of New Zealand

geology at the disposal of any geologist who reads English.
Rew e.

92 REVIEWS

Topologie. Etude du terrain. Par le G&NERAL BERTHAUT. 2
vols., quarto, pp. 674; 265 full-page topographic maps; 65
text figures. Paris: Service Géographique de l’Armée, 1909.

This title covers a masterly philosophical treatise upon the evolution
of land forms. The presentation is founded upon a thorough analysis
of the geologic agencies which co-operate to form and to alter the surface
features. The different classes of topographic features are described
in the light of the various deformative and physiographic processes to
which they owe their origin. These processes are taken up successively,
and as the peculiarities and characteristics of the resulting topography
are minutely described, they are vividly illustrated by the introduction
of topographic maps. The subject is further developed from a discussion
of these maps, which are so numerous as to constitute one of the leading
attractions of the work. Most of the maps are selected from the topo-
graphic surveys of France and the French possessions in North Africa,
with occasional sheets from the Swiss Alps, Norway, and the United

States.
Re leis

La sécurité dans les mines. Etude pratique des causes des accidents
dans les mines et des moyens employés pour les prévenir.
By H. ScuHMERBER. Paris: Ch. Béranger, éditeur, ro10.
Pp. 659; figs. 589.

Now that the people of this country have been awakened to the ned
of greater safety in coal mining and efforts are being made to better the
mining conditions, this new work on the engineering phase of the problem
is very timely. It should be understood, however, that the geological
and strictly scientific aspects of the problem of mine explosions scarcely
enter at all into the author’s treatment and hence the book contains little
of interest to geologists as such. But as an engineering work, which in

truth is all that it attempts to be, it is an admirable treatise.
RC:

Leading American Men of Science. Edited by DAvip STARR
Jorpan. New York: Henry & Holt Co., 1910. Pp. 471,
with 17 portraits.

This volume is made up of biographical sketches of seventeen men
of the past selected as leaders in American science by a zodlogist of
eminence. The selection embraces an astronomer, a chemist, a geolo-

REVIEWS 93

gist, four zodlogists, two ornithologists, two paleontologists, one
anatomist, one botanist—ten out of the seventeen from the biological
group—and four physicists. The individuals chosen and the authors
of the essays are as follows:

Benjamin Thompson, Count Rumford, Physicist. By Edwin E. Slosson.
Alexander Wilson, Ornithologist. By Witmer Stone.

John James Audubon, Ornithologist. By Witmer Stone.
Benjamin Silliman, Chemist. By Daniel Coit Gilman.

Joseph Henry, Physicist. By Simon Newcomb. :

Louis Agassiz, Zodlogist. By Charles Frederick Holder.

Jeffries Wyman, Anatomist. By Burt G. Wilder.

Asa Gray, Botanist. By John M. Coulter.

James Dwight Dana, Geologist. By William North Rice.
Spencer Fullerton Baird, Zodlogist. By Charles Frederick Holder.
Othniel Charles Marsh, Paleontologist. By George Bird Grinnell.
Edward Drinker Cope, Paleontologist. By Marcus Benjamin.
Josiah Willard Gibbs, Physicist. By Edwin E. Slosson.

Simon Newcomb, Astronomer. By Marcus Benjamin.

George Brown Goode, Zodlogist. By David Starr Jordan.

Henry Augustus Rowland, Physicist. By Ira Remsen.

William Keith Brooks, Zodlogist. By E. A. Andrews.

Students of geology will be most interested in the lives of Dana,

Marsh, and Cope, the leading events of whose fruitful scientific careers

are clearly set forth.
Resa:

Geology and Ore Deposits of Republic Mining District. By JOSEPH
B. UmpLtesy. Washington Geological Survey, Bulletin No. 1.
Epos.) fgsis; pl 12). Olympia, 1010:

Physiographically the -Republic mining district in northeastern
Washington appears to be an extension of the Interior Plateau of
British Columbia and to be allied in Tertiary history with it. At the
same time it seems to belong to a different physiographic unit from the
central Cascades.

The oldest rocks exposed in the Republic district are metamorphic,
and are provisionally assigned to the Carboniferous. In early or
middle Mesozoic times there occurred great batholithic intrusions of
granodiorité. Following these came a great period of erosion lasting
until the middle of the Tertiary. During this time there was developed
an Eocene peneplain which was lifted and trenched before the end of

04 REVIEWS

the Oligocene. The rocks next in order are dacite flows of Oligocene
age. The remaining Tertiary history is written in several periods of
igneous activity—andesite flows, intrusive latite porphyries, and a
basaltic eruption during the Pleistocene...

The total bullion production of the camp since the first discovery
of ore in 1896 has been about $2,000,000, of which approximately 90
per cent has been gold and the remainder silver. The veins are thought
to be genetically related to the latite porphyry intrusion and are made
up of quartz, chalcedony, opal, calcite, and adularia, carrying incon-
spicuous amounts of pyrite and possibly gold, in association with anti-
mony, sulphur, and selenium.

Though the deposits at Republic are not altogether like any others
known in the United States, they most closely resemble the lodes of the
Great Basin province. Their striking feature is the great amount of
selenium in the ores, and they are thus best correlated with Tonopah
and Goldfield, the only other camps in the United States known to pro-
duce selenium ores.

The report closes with a detailed description of the principal mines
of the district, of which the New Republic mine is easily the leader.

} aes 1 Ba Ce

Notes on Explosive Mine Gases and Dusts with Special Rejerence
to Explosions in the Monongah, Darr, and Naomi Coal Mines.
By Rortitrin THomAs CHAMBERLIN. U.S. Geol. Surv. Bulletin
383.

The results of a series of experiments carried out by the author throw
new light on the nature of the explosive material and on the conditions
governing explosions in coal mines, and should be of great practical, as
well as scientific, value. As soon as possible after the explosions in the
mines mentioned, samples of the mine atmosphere were collected and
analyzed. Another series of experiments was carried out to determine the
probable condition of the gas in the coal, whether (1) imprisoned in*minute
cavities, (2) occluded or dissolved in the substance of the coal, or (3) the
result of slowly operating chemical processes. ‘This was done by studying
the rate of liberation of gas (1) from coal bottled in vacuum, (2) from
crushing the coal, and (3) from heating the coal. A careful study was
also made of the position and nature of the dust in passage-ways and on
timbers in the mines after the explosions.

REVIEWS 95

It is concluded that if methane were the sole explosive gas, only local
explosions near the face of the coal could result. Coal dust is present,
however, in large quantities and can under proper conditions become
explosive. The chief restraining agent on dust explosion is dampness, and
the presence of a high proportion of non-combustible shale dust. A great
reduction of the moisture in mine atmospheres results from the incoming
of cold air at the beginning of winter, and it is observed that most of the
great explosions have been at that time.

It is a general belief that old dust exposed for a long time to the air
is more dangerous than fresh dust, but the author shows by experiment
that this belief is erroneous, and that fresh dust is the-more explosive.

Reve:

Reconnaissance of the Book Cliffs Coal Field between Grand River,
Colorado, and Sunnyside, Utah. By G. B. RicHarpson. U.S.
Geol. Surv. Bulletin 371.

The field forms a part of the south rim of the Uinta basin, around whose
margin the outcrops of coal-bearing rocks can be traced for more than
five hundred miles. Three formations of Cretaceous rocks are mapped:
the Dakota sandstone lying unconformably on Morrison beds, the Mancos
shale of Colorado and Montana age, and the Mesaverde formation which
is overlain unconformably by Wasatch beds. The Mesaverde is partly
marine and partly non-marine, the marine part showing close similarity to
the upper Mancos shale and the non-marine to the Laramie. The age
is placed as pre-Laramie, the Laramie epoch being supposedly represented
by the unconformity above.

Coal of good quality occurs in the lower part of the Mesaverde forma-
tion in some localities. Several beds are present, but no single bed has
been traced for more than a few miles. The coal of the region is little

developed.
hy 18s IW

Cenozoic Mammal Horizons of Western North America. By HENRY
FAIRFIELD OsBorn, with Faunal Lists of the Tertiary Mammalia
of the West by WittiAM DitLER Matruew. U.S. Geol. Surv.
Bulletin 361.

This report is primarily a correlation of the mammal-bearing horizons
of the Cenozoic with one another and with those of Europe, with a brief
characterization of each horizon. In the Tertiary, six faunal phases are

96 REVIEWS

recognized, containing eighteen subdivisions, while a seventh phase belongs
to the Pleistocene. Three faunal phases containing seven subdivisions
belong to the Eocene, the fourth phase, containing seven subdivisions,
extends through the lower Miocene, the fifth phase extends through the
middle and upper Miocene, and the sixth through the Pliocene. The
conclusion is that North America promises to give a nearly complete and
unbroken history of the Tertiary in certain regions, though much work
still remains to be done. The chief remaining gap is now in the Pliocene
stratigraphy.
Je; Reale

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VOLUME XIX NUMBER 2

LTE

JOURNAL or GEOLOGY

A SEMI- QUARTERLY

EDITED BY

THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
. With the Active Collaboration of

SAMUEL W. WILLISTON ALBERT JOHANNSEN WILLIAM H. EMMONS
Vertebrate Paleontology Petrology Economic Geology

STUART WELLER WALTER W, ATWOOD ROLLIN T. CHAMBERLIN
Invertebrate Paleontology Physiography Dynamic Geology

ASSOCIATE EDITORS

SIR ARCHIBALD GEIKIE, Great Britain GROVE K. GILBERT, National Survey, Washington, D.C.
HEINRICH ROSENBUSCH, Germany CHARLES D. WALCOTT, Smithsonian Institution
THEODOR N. TSCHERNYSCHEW, Russia HENRY S. WILLIAMS, Cornell University
CHARLES BARROIS, France JOSEPH P.IDDINGS, Washington, D.C.
ALBRECHT PENCK, Germany JOHN C., BRANNER, Stanford University
HANS REUSCH, Norway 5 R, A. F. PENROSE, Philadelphia, Pa.
GERARD DEGEER, Sweden p WILLIAM B. CLARK, Johns Hopkins University
ORVILLE A. DERBY, Brazil WILLIAM H. HOBBS, University of Michigan
T. W. E. DAVID, Australia FRANK D. ADAMS, McGill University
BAILEY WILLIS, Argentine Republic CHARLES K. LEITH, University of Wisconsin
FEBRUARY -MARCH, 1911
CONTENTS
THE SOUTHERLY fe LIES wee ce pee OINOR EEGs Ee IN THE ALLEGHENY
REGION - >> - aiong ees CINDER ah 107
THE ae er Ee ie oy CONFORMITY ge aoa SHARON CON-
GLOMERATE mies tice = Sl hy Gar CANBY STO:

THE WICHITA FORMATION OF NORTHERN TEXAS
C. H. Gorpon, Grorce H. Girty, AnD Davi WHITE

NOTES ON THE OSTEOLOGY OF THE SKULL OF‘ PARIOTICHUS'- E. B. Branson

HIGH TERRACES AND ABANDONED VALLEYS IN WESTERN PENNSYLVANIA
EUGENE WESLEY SHAW

REQUISITE “CONDITIONS FOR THE FORMATION OF ICE RAMPARTS
Witt1am H. Hosss

THE TERMINAL MORAINE OF THE PUGET SOUND GLACIER J. Harten Brevz
EDITORIAL:
PES BEDING «ORY WORLDS rect acer i cular hint wdc, Rog wae TEESE Dane ee lat CoG
ARTESIAN WATERS OF ARGENTINA - - - - A Si ade ee aie ne od eee WW
PE EROGRAPHICAL) ABSTRACTS, AND REVIEWS = - >= => 0-02 2 ase ee
ROB; WET Sistah, Oc (= apenas amt em lens Ree) GE eR USN Eh Pe toh ah del a) ie a ge

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Uae Bix ALR VIVA RC, TOL:

THE SOUTHERLY EXTENSION OF THE ONONDAGA
SEA IN THE ALLEGHENY REGION*™

E. M. KINDLE

It is proposed in this paper to present some of the evidence
which calls for a distinct modification of the current conception
of the extent of the Onondaga sea in the eastern part of the United
States. Before submitting the new data the reader’s attention will
be invited to certain features of the previously recorded faunal
and lithologic facts relating to the Onondaga sediments which,
in the writer’s opinion, have led to some misconceptions regarding
the character and extent of the Onondaga sea in the eastern states.

The Onondaga fauna as developed in the states of New York,
Ohio, Indiana, and Kentucky was one of the first of our Paleozoic
faunas to be studied and described. The reports of the state sur-
veys of these states, supplemented by numerous unofficial papers
in which this fauna has been recorded and illustrated, have made it
one of the best known of the Paleozoic faunas. It is a noteworthy
fact, however, that all of the various contributions to our knowl-
edge of this fauna have dealt with a nearly pure limestone fauna.
If one were to seek a comprehensive idea of the character of the
Onondaga sea and its sediments from the published descriptions
of the fauna and the limestones holding it, he would get the con-
ception of a sea in which only limestones were deposited. To any-

t Published by permission of the Director of the United States Geological Survey.
Vol. XIX, No. 2 O7

98 E. M. KINDLE

one who admits that the factors controlling marine sedimentation
were essentially the same in Paleozoic and recent times, a Devonian
sea in which only calcareous sediments accumulated is a manifest
absurdity. We know of no continental or other seas in which
there are not a variety of types of sediment accumulating simultane-
ously. Papers which have undertaken to deal with this fauna in
a large way and weld its evidence into the new science of paleo-
geography have naturally been influenced by the fact that the only
faunas described from the Onondaga sea were limestone faunas.
Translated into the form of a paleogeographic map this class of
evidence taken alone gives us a sea whose outlines inclose only
limestone sediments. This was a serious defect in Professor
Charles Schuchert’s first map of the Onondaga sea.t. The shore-
lines given by it for the Onondaga sea in the central states inclosed a
sea from 100 to 300 miles in width. All of the known Onondaga
deposits included by the shorelines of the map are limestones.
The recently published map of the middle Onondaga by Professor
Schuchert? shows improvement in this respect, since it includes the
shales and argillaceous limestone bands holding the Onondaga
fauna which was discovered in central Pennsylvania by Charles
Butts and determined by the writer. The later map, however,
still gives us a conception of the Onondaga sea far from that which
the writer’s recent studies in the Allegheny region appear to
demand. The writer’s criticism, it may be stated here, is directed
primarily, not to Professor Schuchert’s map, which incorporated
all of the positive evidence available at the time of its preparation,
but at the incompleteness of the evidence in a region where it might
be expected to be fairly complete.

In order to ascertain to what extent recorded evidence and
opinion will enable us to reconstruct the shorelines of the Onondaga
sea within the limits of the eastern states so that they will appear
consistent and rational with reference to the character of the known
deposits of that sea, we may consider briefly the principal sources

* Charles Schuchert, ‘On the Faunal Provinces of the Middle Devonic of America
and the Devonic Coral sub-Provinces of Russia, with Two Paleographic maps,” Am.
Geol. (1903), XXXII, 137-62, Pl. 20.

2 Charles Schuchert, ‘‘Paleogeography of North America,” Bull. Geol. Soc. Am.,
XX (1910), 75.

THE ONONDAGA SEA IN THE ALLEGHENY REGION 99

of its sediments. The comparatively thin mass of sediment which
accumulated during the whole of the Devonian in the central states
affords satisfactory evidence that the land area adjacent to the
Devonian sea on the west had slight relief, and furnished compara-
tively little sediment at any time during the Devonian. On the
east side of the Devonian sea, however, physiographic conditions
were very different. Willis' has shown that during much of the
Devonian period there lay immediately southeast of the Alle-
'gheny region the highlands of Appalachia. This old land area
furnished to the interior Devonian sea of the Appalachian region,
between the beginning of the Hamilton epoch and the close of the
Devonian, a mass of sediments which, if restored upon a sea-level
plain of Appalachia, ‘would constitute a mountain range closely
resembling in height, extent, and mass the Sierra Nevada of
California.’

According to the prevailing view: this fertile source of Devonian
sediments was elevated at the close of the Oriskany to such an
extent that throughout Onondaga time the Allegheny region was
a land area. Such elevation, if it occurred, must have resulted
in accelerated erosion in the Devonian highlands, and in an in-
creased volume of sediments in the Onondaga sea. If this hypo-
thetical uplift occurred, it could not have failed to have been
registered by a great thickness of coarse clastic sediments in the
narrow Onondaga sea which, as outlined by Schuchert’s map,
extended as a narrow belt across the adjacent portions of the
present states of Kentucky, Indiana, and Ohio. Instead of such
coarse clastics we find in these states, as previously noted, only
limestones. representing. sedimentation near the eastern shore of
the Onondaga sea as outlined by Schuchert.4 The utter impossi-
bility of harmonizing the pure limestone deposits representing the
Onondaga in the Ohio valley with this currently accepted theory
of diastrophism in the Allegheny region would appear to be a suff-
cient reason for discarding it. If, however, we assume that Appa-

t Md. Geol. Survey, Special Publication, Vol. IV, Pt. I, pp. 61-62.

elbtd eps 62:

3 Charles Schuchert, ‘‘Paleogeography of North America,” Bull. Geol. Soc. Am.,
XX (1910), 492.
siibtds. Rls 7s.

100 E. M. KINDLE

lachia was not elevated and the Devonian shoreline was not pushed
westward at the initiation of Onondaga time, we would still expect
as a probability non-calcareous sediments to predominate in the
eastern portion of the Onondaga sea. That portion of the Onon-
daga sea adjacent to the land area which furnished 10,000 feet of
non-calcareous Devonian sediments in post-Onondaga time would
be likely to acquire chiefly non-calcareous sediments even in an
epoch so favorable to calcareous sedimentation as the Onondaga.

A considerable mass of paleontologic and stratigraphic data
which has been gathered by the writer shows that Onondaga sedi-
ments are present in the Allegheny region and are mainly of this
non-calcareous type, as might have been expected from theoretical
considerations. The recent discovery of an Onondaga fauna
in the Allegheny region which occurs in a series of drab or
dark shales and thin interbedded argillaceous limestones thus
very materially supplements the hitherto one-sided character of
the available data relating to the nature of the fauna and sediments
of the Onondaga sea. The sediments holding this fauna are of
such a character as we might have expected to be accumulating
on some portion of the Onondaga sea floor if we may judge by
analogy with the processes of sedimentation now in operation in
the largest continental seas. Since this fauna will be described and
figured in a forthcoming bulletin of the United States Geological
Survey, only the most general facts regarding it will be presented
here. The fauna comprises more than one hundred species. The
correlation of this Allegheny fauna with the New York Onondaga
fauna is based primarily upon the presence in it of such well-known
species as Ano plotheca acutiplicata, Rhipidomella vanuxemt1, Spirifer
acuminatus, and Odontocephalus aegeria. The great abundance and
general distribution of the first named of these species is a con-
spicuous characteristic of the fauna. In point of abundance and
wide distribution in this argillaceous facies of the Onondaga,
Ano plotheca acutiplicata is as prominent as is Spirifer acuminatus in
the well-known calcareous facies. It is interesting to note in this
connection that while Anoplotheca acutiplicata is a familiar species
in the Onondaga limestone of eastern New York comparatively near
the region under discussion, it is unknown in the more westerly areas

THE ONONDAGA SEA IN THE ALLEGHENY REGION 101

of the limestones of Onondaga age in Ohio, Indiana, and Illinois.
Its occurrence in typical Onondaga limestone only in an area which
is nearly adjacent to the region of the shaly facies of the formation
suggests that the latter type of sediments furnished its normal and
most congenial habitat. Spzrifer acuminatus, on the other hand,
does not extend very far to the southward into the region occupied
by the argillaceous facies of the Onondaga. Other Onondaga
species, however, like Odontocephalus aegeria, appear to be equally
adapted and distributed in both types of sediment.

Some of the stratigraphic data relating to this fauna may be
very briefly summarized as follows:

The calcareous shales holding this fauna are generally preceded
in the sections by the Oriskany sandstone and always followed
by the dark fissile and comparatively barren shales of the Marcel-
lus. These two limiting formations exhibit in general essentially
the same lithologic characters throughout Pennsylvania, Mary-
land, West Virginia, and much of Virginia as in New York. Both
are, however, much thicker in this more southerly region than in
the type region of the Onondaga limestone in New York. In the
Helderberg mountain region the Onondaga and the Hamilton
faunas are separated by 300 feet of comparatively barren dark
Marcellus shale, and in western New York by about half this thick-
ness, while in Pennsylvania and southward these shales often have
a thickness of more than 500 feet.

While the succession from the Onondaga fauna to the Marcellus
fauna above is a uniform one throughout most of the Allegheny
region, as it is in New York, the succession at the base of the fauna
is not everywhere precisely the same. In most of the territory the
Onondaga beds rest upon the Oriskany, but in some of the Penn-
sylvania sections they immediately follow beds representing the
Esopus shale. In respect to its underlying formation, however, the
Onondaga shows less variation than in New York, where, in different
areas, it is found to follow the Manlius, Oriskany, Esopus, and
Schoharie. Thus, we find that this fauna occupies in the Allegheny
region the same relative position in the succession of faunas as the
Onondaga fauna does in the standard sections of New York. The
stratigraphic evidence, therefore, coincides with the paleontologic

102 hk. M. KINDLE

evidence already briefly cited in pointing to the Onondaga age of
the fauna. We may now consider the bearing of the data which
have been cited on the modification of the current conception of
the eastern shoreline of the Onondaga sea in the eastern United
States.

The Onondaga formation extends scarcely south of the Dela-
ware River according to most of the papers dealing with the stratig-
raphy of the Devonian in the Allegheny region, thus giving it a
north-south extension of scarcely 200 miles. This comparatively
insignificant southerly extension of a fauna which is so persistent
in a westerly direction seems more surprising when it is recalled
that all of the other faunas characterizing the major divisions of
the New York Devonian section have with one or two exceptions
been traced southward from New York entirely across Pennsyl-
vania. Thus itis seen that the prevailing conception of the
Onondaga formation and fauna, which presumes their absence
south of New York, gives to it an anomalous position as compared
with the other important formations of the Devonian section of
New York. The evidence which the writer has gathered during
three seasons of field work in the Allegheny region indicates that
the southerly extension of the Onondaga fauna is quite comparable
in distance with its westerly extension. The field studies of the
writer have shown that the Onondaga fauna in the Allegheny region
extends far to the southward of the area in which nearly pure
limestones were deposited during Onondaga time into a region where
shale-forming sediments partially or completely dominated those
of calcareous type. This fauna has been found in nearly all the
sections studied from New York to Tennessee.

The direct bearing of these new data on the paleogeography of
Onondaga time is obvious. Its incorporation involves the exten-
sion of the eastern shoreline of the Onondaga sea in a southwesterly
direction from southeastern New York to the eastward of the
Allegheny region instead of far to the westward of it, as now drawn,
across the states of Ohio, Indiana, and Kentucky. In the light
of this new evidence it appears that the eastern shoreline of the
Onondaga sea trended southwesterly across north-central New
Jersey and southeastern Pennsylvania. It probably traversed the

THE ONONDAGA SEA IN THE ALLEGHENY REGION 103

states of Maryland and Virginia near the present axis of the Blue
~Ridge Mountains. From southwestern Virginia this shoreline
appears to have trended westerly not far from the Kentucky-
Tennessee line as far as the valley of the Tennessee River where
it resumed its southerly trend. This revision of the shorelines of
the Onondaga sea gives, instead of the Cincinnati peninsula of
Schuchert’s map, a Cincinnati island. This, and probably other
smaller islands, interrupted the continuity of the Onondaga sea,
which, in the region of the Ohio valley, reached a maximum width
of about 500 miles from northwest to southeast.

THE MISSISSIPPIAN-PENNSYLVANIAN UNCON-—
FORMITY AND THE SHARON
CONGLOMERATE"

G. F. LAMB
Mount Union College

There exists in northern Ohio a well-defined boundary between
the strata of the Mississippian and Pennsylvanian ages, a boundary
marked by a pronounced unconformity. The upper limit of the
Mississippian is the top of the well-known Cuyahoga formation,
and the lower limit of the Pennsylvanian is the bottom of the
equally well-known Sharon conglomerate.

So far as the writer is aware the Sharon has been generally
regarded as a formation of general extent around the northern and
northwestern border of the Appalachian coal basin, and resting
upon the Mississippian in a continuous sheet except where removed
by erosion.

Field work the past summer in Mahoning, Trumbull, Portage,
Summit, and Geauga counties has revealed some facts that lead
the writer to believe that the Sharon conglomerate is not the
simple formation that it has been thought to be, and that it has a
setting of unusual interest.

Following its outcrop from place to place, the formation is
found to change in structure quickly, to disappear suddenly, and
to be absent over considerable areas, letting later rocks form the
contact with the Cuyahoga. Where its development is greatest,
it les in troughs of the Cuyahoga. Further, it is found to occur
in belts having a more or less north-and-south direction, and these
belts, in places at least, are not now and never have been connected
from east to west. This is due, in part at least, to the fact that the
conglomerate lies between ridges of the Cuyahoga, and not alone
to post-Pennsylvanian erosion.

t Published by permission of Dr. J. A. Bownocker, state geologist of Ohio. Pre-
sented at the twentieth meeting of the Ohio Academy of Science, Akron, November
25, I9IO.

IO4

MISSISSIPPIAN-PENNSYLVANIAN UNCONFORMITY 105

This manner of occurrence calls attention to the surface upon
which the Pennsylvanian rests. Whatever may be the case else-
where, the writer believes that greater erosion of the upper Missis-
sippian occurred in northern Ohio than is generally known. Instead
of the Sharon resting upon a nearly uniform plane, it is found that
the surface of the Cuyahoga has a relief of nearly 200 feet, and it
is significant that where the depressions are greatest, the Sharon
is also thickest. The regional or belt-like occurrence of the con-
glomerate, and its apparent relationship to depressions in the
Cuyahoga, along with the structure and variability of the stratum,
have led the writer to the conclusion that these depressions are
creek and river valleys, and that the conglomerate is a deposit
of stream gravels, and that the overlying sandstones of the Potts-
ville are, to a greater or less extent, river and delta deposits.

Some of the data on which this view is based are added. Val-
leys in the Cuyahoga formation are of general occurrence. The
most conspicuous and deepest one so far found may be noted in
some detail. This valley lies in the eastern edge of Portage and
Geauga counties, about half-way between Akron and the state
line, and its course is roughly north and south. At Akron, the
top of the Cuyahoga formation lies about 940 above sea; due east,
at Mineral Ridge, west of Youngstown, at 962; at Newton Falls,
between these two points, and 5 miles north of the Akron-Mineral
Ridge line, it lies below 850, or about 100 feet lower than to the
east or west. If such a line be drawn from east to west half-way
between Akron and Cleveland, the same depression in the Cuya-
hoga is again found. At Brandywine Falls, 15 miles north of Akron,
the top of the Cuyahoga formation lies at 1,040; near Howland
Springs, due east of Brandywine, at 1,044; and at Nelson Ledges
between these two points at 956, or again nearly 100 feet lower.

Another east and west comparison may be cited. At Burton,
due east of Cleveland, the top of the Cuyahoga lies at 1,090 and
due east on the state line at 1,190, or 100 feet higher. These three
middle points—Newton Falls, Nelson Ledges, and Burton—are in
line, roughly, north and south, and are clearly in a depression of
the Cuyahoga formation, since rock of this formation lies higher
both to the east and west. Further, this depression cannot be

106 G. F. LAMB

assigned to a syncline, as is proven by the nearly horizontal posi-
tion of the Berea in the same direction. It is worthy of note that
the Sharon and overlying sandstones in the line of this old valley
reach their greatest development in Ohio, and form a great body of
conglomerate and sandrock extending southward from southern
Lake County, through Geauga and Portage counties, at least as
far south as northern Stark County. ‘The evidence is strong that
the conglomerate and overlying sandstones in this great ridge are
stream deposits, and will be discussed later.

It may be objected that the distances involved in the three
lines across this supposed valley are of such length as to be of
doubtful value. Data are at hand, however, which confirm fully
what the three lines of elevation show. At Brandywine the Sharon
base is 210 feet above the Berea; due east at Nelson Ledges only
about 75 feet; near Newton Falls only about 75 feet; but on the
state-line nearly due east of Nelson Ledges nearly 300. The
meaning of these figures is clear, and shows deep erosion, which is
still further confirmed by the presence of hills of the Cuyahoga in
the very region in which the erosion was greatest. As stated above,
the top of the Cuyahoga near Newton Falls lies below 850 and in
2+ miles north rises to 1,040 above sea-level. It therefore forms
a hill at least 190 feet high, with no trace of the Sharon or overlying
sandstones. Within 35 miles to the northwest from this hill,
and in a direction opposed to the dip, the surface sinks to g19
feet at least. At Nelson Ledges the conglomerate is about 75
feet thick, and one solid mass from bottom to top. It appears
to the observer that it may be expected to continue for miles
to the north, but instead it thins out quickly on the steep slope
of another Cuyahoga hill, which rises from 956, at the base
of the Ledge:. to i1o7,7a) ise, oh 15m Teet) ant emilee NVae mm
2 miles to the northwest from this hill, the surface drops
again to gogo, or 117 feet, as seen in the Parkman gorge.
From this point the surface rises again to the northeast, 180 feet
in 24 miles, then falls toward the northwest. At Newton Falls,
there is a like rise toward the northeast from below 850 to 941, in
about 3 miles. Now all points which show these old hills are on
or near the eastern margin of this rock ridge, and in every case

MISSISSIPPIAN-PENNSYLVANIAN UNCONFORMITY 107

bear evidence of a more or less westerly slope toward the ridge.
They are clearly hills bordering a valley, and are conclusive evi-
dence of former dissection to a depth of nearly 200 feet. This same
hill and valley topography of the Cuyahoga is found all through
eastern Trumbull and northern Mahoning counties, with the
conglomerate often absent, and with the Sharon coal lying close
above the Cuyahoga.

One of the finest exposures of the unconformity occurs in Mineral
Ridge, south of Niles, and near the Mahoning-Trumbull line.
A deep east-and-west ravine cuts through a north-and-south
Cuyahoga ridge finely exposing the contact, showing the horizontal
shale and flaggy layers of the Cuyahoga, overlain by the steeply
inclined strata of the Pennsylvanian. ‘The slope of the Cuyahoga
is toward the east, and at an angle of about 25°, is ragged or stair-
step like, and is directly overlain by 2 or 3 feet of crude, mixed
sandstone, without lamination or bedding planes, which grades
quickly into a bluish shale, then to a carbonaceous shale which
carries the well-known and formerly much-worked bed of iron ore.
The ore is a highly ferruginous limestone, which is certainly the
Lowellville limestone. Directly above the ore is a bed of coal—
the Mineral Ridge coal—which lies only 8 feet above the Cuyahoga.
The sandstone, shale, ore, and coal all lie at the same steep angle
above the Cuyahoga.

I have stated above that the Sharon conglomerate bears evi-
dence of being a stream deposit. This appears from its position,
its constitution, and its structure. In some places it is little else
than a mass of quartz pebbles which range in size from coarse sand
to half the size of the fist. (Commonly the stratum is an alterna-
tion of sand beds and pebble layers, of constant variation both
horizontally and vertically. Bottom-set, fore-set, and top-set
beds are common. The sudden change from sand to gravel, and
the very variable structure of the sand beds, all of which may be
repeated several times in a single rock face, can be accounted for
only by stream action. There is not any feature of the con-
glomerate that stream action does not produce. On the other
hand, the writer is unable to conceive of any other agency capable
of producing a like stratum.

108 (GSE EANEB

It will be interesting to note the most exaggerated conglomeratic
development found. It occurs at the base of the Sharon as exposed
in the gorge at the village of Parkman, Geauga County. Lying
directly upon the Cuyahoga, and representing a stream velocity
of probably 3 miles an hour, is a 3-foot bed composed not of pebbles
alone, but of cobble stones, or pieces of flagstone from the Cuyahoga,
some angular, some rounded and flat and well worn, 2 to 3 inches
thick and more than a foot in diameter, standing and lying in all
positions and mixed with sand and pebbles. It is a veritable
picture of the stones and gravel and sand all mixed that we have
all seen many times on the inside curve of streams. A more con-
vincing evidence of stream deposit in former ages can hardly be
found.

It is worthy of note here that two distinct stages in the deposi-
tion of the Sharon are displayed in this gorge. At to or 12 feet
above the base the conglomeratic character is entirely absent, a
rather fine soft sandstone occurs, the top of which is quite undulat-
ing, as if eroded. Resting directly upon the undulating surface,
with a sharp line, is the massive conglomeratic rock characteristic
of the Sharon. The transition is sudden and very conspicuous and
is well shown at a number of points in the gorge.

At Nelson Ledges the base of the conglomerate lies at 956, and
3 mile west conglomerate is found at 1,160 above sea. This whole
thickness of 204 feet is not to be assigned to the Sharon, however.
Overlying sandstones are conglomeratic in this locality and suffi-
ciently so to be mistaken easily for the Sharon itself. Two miles
south of this point and about $ mile south of Nelson village at
Ledge Haven Mill conglomerate rock is found on Tinker Creek.
There are clearly two stages of conglomerate formation here. The
bed of the creek below the fall is conglomerate of unknown thick-
ness. It is directly overlain by 5 to 6 feet of dark gray sandy shale
and this is overlain in turn by 30 to 4o feet of conglomerate. The
top of the lower stratum lies at 952, as seen at the foot of the fall
beside the mill. The shale stratum is strongly suggestive of the
horizon of the Sharon coal. It also strongly suggests relationship
to the two-stage phase of the conglomerate observed in the Parkman
gorge. At the latter place this transition occurs at a level of about

MISSISSIPPIAN-PENNSYLVANIAN UNCONFORMITY 109

1,000 feet above sea, and is nearly 5 miles north of the above mill,
and when dip is taken into account the probability is very strong
that the phenomena seen at the two places belong to the same
horizon.

A quite singular feature occurs in this shale at the fall. Near
its middle, and imbedded in it, lies a lenticular mass of conglomerate
a foot thick and probably weighing nearly a ton. It contains large
quartz pebbles, much pyrites of iron, and an impression of a cala-
mite. How was it transported to this place where only fine sedi-
ments were being deposited? Where did it come from, and from
what rock formation was it detached? For the conglomerate beneath
must have been only a stratum of sand and gravel when it was
deposited. In central Ohio three other formations intervene
between the Cuyahoga and the base of the Pennsylvanian, the
lower one of which—the Black Hand—is known to be conglom-
eratic in part. Is this conglomerate block imbedded in this shale
a remnant of the Black Hand which once may have overlain the
Cuyahoga in northern Ohio, and was completely removed by
erosion before the close of the Mississippian? ‘These are ques-
tions to which only further study may reveal the answer.

THE WICHITA FORMATION OF NORTHERN TEXAS!

C. H. GORDON
University of Tennessee, Knoxville, Tenn.

With discussions of the Fauna and Flora by
GEORGE H. GIRTY ann DAVID WHITE

INTRODUCTION

The geology of the “Red Beds” area of northern Texas has
long been recognized as one of the perplexing problems of North
American geology. The interest aroused by the discovery in these
beds of a fauna which was regarded by Cope, C. A. White, and
others as Permian has brought forth a number of papers bearing
on this region, most of which are based on transient visits In search
of fossils, generally with scant attention to the detail of stratig-
raphy.

This paper is based upon investigations made in connection
with the study of underground water conditions for the United
States Geological Survey during the field seasons of 1906 and 1907.
The collections of invertebrate fossils made in the course of the
investigations were submitted to Dr. George H. Girty of the Survey,
who also had for study additional materials collected by E. O.
Ulrich in former years.

STRATIGRAPHY OF THE REGION

The ‘‘Red Beds”’ area.—The area occupied by the “Red Beds” in
northwestern Texas is bounded on the west by the eastern escarp-
ment of the Llano Estacado, and extends eastward along the Red
River to Montague County, where the formations pass from sight
beneath the basal beds of the Cretaceous. From this point the
eastern boundary of the “‘Red Beds” bears south and then west-
ward, following approximately the lines between Jack and Clay,
and Young and Archer counties as far west as the Salt Fork of
the Brazos. From this point it bears southwestward to the south-

« Published by permission of the Director of the United States Geological Survey.

IIo

WICHITA FORMATION OF NORTHERN TEXAS III

eastern corner of Haskell County, thence irregularly south until
it meets the Cretaceous again in Concho County.

As thus outlined, the “Red Beds” occupy an area of irregular
shape 80 to roo miles in width in the southern portion, while at

{ 4

ATV
Pana

Quaternary [__] PERMIAN :
Recent Seymour Undifferentiated Wichita
Deposits Gravel Clear Fork and Formation

Double Mountain

PENNSYLVANIAN ‘wiih
Cisco Canyon Strawn
Formation Limestone Formation

the north they extend eastward fully twice that distance along the
south side of Red River. If a line be drawn from a point on Red
River near the mouth of Pease River southwestward through
Seymour to the northeastern corner of Haskell County and thence
southward, it will mark approximately the eastern boundary of a
series of red clays and red sandy shales containing gypsum in vary-
ing amounts, to which the names Clear Fork and Double Mountain

IRIED) C. H. GORDON

were applied by Cummins in reports of the Texas Geological Survey.
These are evidently the equivalents of the beds included by Gould?
in the formations to which he applied the names Greer and Quarter-
master. As these beds have no connection with the problem in
hand, they may be dismissed from further consideration. It is
to that portion of the “Red Beds” area adjoining the Red River
and extending eastward from the line above indicated that most
of the discussions concerning the Texas Permian apply. This is
the type area of the Wichita formation of Texas. ‘The western
part of this area is characterized by the occurrence of beds of
limestone and blue shale interbedded with red clays and sandstones,
while the eastern part is notable for the entire absence of limestones
and the very limited development of blue shale and clay. If a
line be drawn from a point where the Salt Fork of the Brazos crosses
the boundary between Throckmorton and Young counties, a little
east of north to Red River, it will mark approximately the boundary
between the areas thus lithologically distinguished. According to
Cummins’ earlier writings? most of the rocks of this western area
were assigned to the Clear Fork formation, while the strata occur-
ring toward the east constitute his original Wichita division. Many
of the fossils on which his conclusions regarding the Permian age
of the beds were based, however, appear to have come from the
basal portion of the limestone series in eastern Baylor County.
In the earlier reports the Wichita formation is described as hav-
ing no surface development south of the point where the “Red
Beds” boundary meets the South Fork of the Brazos River in the
northeastern corner of Throckmorton County. From that point
southward the Clear Fork formation is said to rest directly upon
the “Albany,” considered to be the highest division of the “Coal
Measures” in that region. This peculiar relation of the Wichita
formation was conceived to be due to overlap, and hence it was
believed that an unconformity marked the relations of these beds
to the “‘Coal Measures.” In a later paper,? read before the Texas

Charles N. Gould, Water-Supply and Irrigation Paper No. rg9t (1907),
14-19.

2 Geological Survey of Texas, II (1890), 401. See map facing p. 552.

3.W.C. Cummins, Transactions of the Texas Academy of Science (1897), I1, 93-907.

WICHITA FORMATION OF NORTHERN TEXAS 113

Academy of Science, Cummins announced the discovery of evidence
showing that the limestones of eastern Baylor County are the same
as those of the “‘Albany.”’ In this paper the beds of Baylor County
are said to constitute the upper part of the Wichita. Owing to
the discontinuance of the Texas Survey the report on this area
prepared for the Fifth Annual Report has not appeared.

Rocks of the Wichita area.—KEast of Baylor County the rocks
consist for the most part of red concretionary clays, red sandstones
and sandy shales with occasional beds of blue shales, and bluish
to grayish-white sandstones. Limestones are conspicuously absent.
Occasional impure nodular layers occur, however, which contain
considerable calcareous matter, but these do not constitute strata
of limestone. The sandstones are usually soft and distinctly cross-
bedded. In some places they are shaly, in others massive. Some
layers are streaked and specked with grains of black iron oxide,
while others contain nodular masses and concretions of iron ore.

The clays are mostly deep red or red mottled with bluish-white
and drab colors. ‘The red clays contain an abundance of nodular
concretions of irregular shape varying in size from that of a pea to
masses 4 or 5 inches in diameter. They consist of clay, iron, and
lime, and at times are hollow or with the interior filled with cal-
careous clay or lime carbonate. In some cases they are flattened
and stand in vertical position in the clays, suggesting their origin
through the filling of fissures.

Occasionally a bed is met with consisting of rounded lumps of
hardened clay cemented together by ferruginous matter, repre-
senting what Cummins called “‘a peculiar conglomerate.” This
formation is believed to have had its origin in the breaking-up of a
bed of clay by running water or wave action.

In places the bluish clays are copper bearing. Efforts to mine
these deposits, however, have not been profitable. The ore occurs
in the form of small nodules in the clays and also as a replacement
of wood."

In the sandstones occasional traces of plants occur, and some-
times remains capable of identification are found. White reports
Taeniopteris from the sandstones near Fulda. The stratification

ry. F. Cummins, First Annual Report, Geological Survey (Texas, 1889), 188-96.

II4 C. H. GORDON

of the beds is very irregular. The sandstones, shales, and clays
grade into each other both vertically and horizontally. Moreover
there is a monotonous similarity in the sandstones and _ shales
respectively throughout the area, which, taken in connection with
the absence of any persistent easily recognizable stratum, renders
the stratigraphic correlation of the beds, except within very narrow
limits, practically impossible.

In eastern Clay and Montague counties, the beds, considered
Cisco, show a greater development of sandstones some of which
are conglomeratic. In the western part of the area, however, no
true conglomerates were observed.

As to the thickness of the Wichita, no definite statement can
be made. Certain of the beds may be traced for a limited distance
sufficient to indicate a general westward dipping of the strata.
Cummins estimates it to be 35 feet per mile, which is probably
too high. The width of the outcrop in an east-west direction is
about 50 miles, which, assuming a regular inclination of 25 feet
per mile, would give a thickness of 1,250 feet for the beds out-
cropping in this portion of the field. How much of this should be
referred to the Cisco is conjectural, but probably not less than
half. A well put down for oil at Electra, which is located near the
top of the formation, passes through 1,790 feet of red clays with
some sandstone and red sandy shales. At Petrolia, which is near
the middle of the outcrop, the oil wells are for the most part about
400 feet deep, chiefly in red clays and shales. Drilling has extended
to a depth of 800 feet in some instances and indicates an increase
in the proportion of blue shales below, but no reliable record could
be obtained of the lower formations passed through.

At Archer City a well 737 feet deep shows red clays and reddish
sandstones predominating to a depth of 670 feet. Below this the
drill revealed similar deposits but in diminished proportion, as
compared with the light-colored sands and bluish clays. Since
thé upper beds of the Cisco in this region are prevailingly red, how-
ever, no reliable conclusion can be drawn from well records as to the
plane of division between the formations.

In the bluffs of the Wichita River in the northwestern corner
of Archer County some beds of limestones aggregating 4 feet in

WICHITA FORMATION OF NORTHERN TEXAS 5

thickness appear at the top of the escarpment on the west side of
Horseshoe Lake, and outcrops of these appear at intervals along
the boundary of Archer and Baylor counties. This limestone is
earthy, very hard, dark blue where fresh, and weathers to dark
brown or black. It is underlain by 4 feet of blue clay. The
remainder of the section to the base of the hill, about 100 feet,
consists of red concretion-bearing clays with a limited development
of red and white shaly sandstone. From this point westward the
stratification becomes more regular, consisting of the blue shales
alternating with the red, the red being predominant, with an occa-
sional bed of dark earthy limestone containing usually an abun-
dance of poorly preserved fossils.

At the Bar-X ranch on the Wichita River in the northeast cor-
ner of Baylor County near the Old Military Crossing, several ledges
of hard limestone appear in the river bluffs separated by varying
thicknesses of blue shale, alternating with red clay. The beds
dip to the westward at inclinations estimated at 20 to 30 feet per
mile. Proceeding up the river from this point, limestones appear
at intervals in increasing development, the best outcrops occurring
about 2 miles east of where the Seymour-Vernon road crosses the
river. Here an escarpment go feet in height has the lower two-
thirds composed of red and blue shales alternating with beds of
limestone. The middle of the section consists of red and concre-
tionary clays and sandstones. Some of the ledges of limestone
are massive, but others are thin-bedded and shaly, and separated
by varying thicknesses of bluish clay. Locally the thin-bedded
limestones and their included shale grade horizontally into more
massively bedded limestones. Fossils are not plentiful in this
locality. The same beds are exposed again northward in the
banks of Beaver Creek. At Seymour the limestones are well
exposed in the banks of the river where they are quarried to some
extent and furnish a stone that is well adapted to ordinary uses.
The beds are here transected by the Salt Fork of the Brazos River,
which flows in a relatively narrow valley between steep bluffs 200
feet high, made up of interbedded red and blue clays, and lime-
stones.

The limestones of Baylor County area are generally fossil-

116 C. H. GORDON

iferous. Owing to the hardness of the rock, however, good speci-
mens are difficult to obtain. Toward the south there is an increase
in the development of blue shale and limestone, while the red clays
and sand show a corresponding diminution. In a recent paper’
Case has endeavored to correlate certain of the sandstones occur-
ring throughout the area, one of which he calls Fulda, from a little
station by that name in eastern Baylor County. With this sand-
stone he correlates others which outcrop as far east as Wichita
Falls, a distance of 37 miles. With this conclusion the writer is
not in accord. In the first place, the sandstones at Fulda are
underlain by some thin limestones which outcrop toward the north-
east in the northwestern part of Archer County. It is quite
apparent that the sandstones in eastern Archer and Wichita
counties represent horizons below these limestone beds. Assum-
ing the general westward dip of the strata to be no more than 20
to 25 feet per mile, there must be a descent of not less than 650
to 800 feet to which must be added the rise of the plateau surface
which is about 200 feet, making a total of 850 to 1,000 feet between
the horizon represented at Wichita Falls and that at Fulda and
rendering untenable the correlations suggested.

Albany area.—The eastern boundary of the Clear Fork and
Double Mountain formation in eastern Jones County is marked
approximately by the Clear Fork River. The region to the east
of this point to the limits of the Cretaceous in western Parker and
Wise counties, a distance of over too miles, known as the Brazos
Coal Field, is occupied by rocks of Carboniferous age. These beds,
which have a thickness of nearly 7,000 feet, present lithological,
stratigraphic, and faunal characteristics, which permit their
separation into four well-marked divisions, known as the Strawn,
Canyon, Cisco, and “Albany” divisions.? Southward in the Colorado
Coal Field the equivalent rocks were first studied by Tarr,’ who

rE. C. Case, Bulletin of the American Museum of Natural History, XXIII (1907),
659-064.

2 These names appear first in the First Annual Report of the Geological Survey of
Texas in the State Geologist’s ‘‘Report of Progress,” pp. Ixv—lxvii. Hill, however,

credits them to Cummins (Twenty-first Annual Report, U.S. Geological Survey, Part
VII, 97).

3R.S. Tarr, First Annual Report of the Geological Survey of Texas (1889), 201-16.

WICHITA FORMATION OF NORTHERN TEXAS in,

subdivided them into five divisions as follows: Richland, Milburn,
’ Brownwood, Waldrip, and Coleman. Later the Milburn was
included in the Brownwood.t The relations of these rocks as now
recognized are as follows: ?

Colorado Field (Tarr) Brazos Field (Cummins) Thicknesses in Feet
Coleman “Albany” 1,200
Waldrip Cisco 800
Brownwood }

: - Brownwood Canyon 800
Milburn \ _
Richland Strawn 4,100

The beds dip to the west at a low inclination estimated by
Cummins to be 30 feet per mile for the “Albany” and 75 for the
Canyon. :

Limestones constitute the dominant characteristics of the
“Albany” and Canyon formations, while sandy shales and sand-
stones, with some conglomerates, make up the larger part of the
Strawn and Cisco formations. It is with the two uppermost of
these, the ‘“Albany’’ and Cisco, that the ““Red Beds” problem is
concerned.

The “Albany.”’—The “‘Albany,’’ named from the county seat of
Shackelford County, consists of blue, gray, and yellowish lime-
stones, alternating with beds of blue and dark-gray shales. The
upper 500 feet are characterized by massive beds of hard blue
limestone, with partings of blue shale, while the lower portion
shows a greater development of shale, the limestone being for the
most part thin-bedded and shaly. The heavy ledges of limestone
appear at the surface in a succession of terraces which extend in
sinuous curves from north to south. Sandstones and conglomerates
are almost entirely lacking. The formation contains an abundant
marine fauna, which, taken in connection with the notable devel-
‘opment of limestones, indicates deep seas and quiet conditions of
deposition. Above, the formation grades rather abruptly into red
gypsiferous clays and red sandy shales and sandstones. The base of

~R. T. Hill, Twenty-first Annual Report of the U.S. Geological Survey, Part VIL
(1899, Ig00), 98.

2 The thicknesses cited are those given by Drake, ‘“‘ Report of the Colorado Coal
Field of Texas,” Fourth Annual Report, Texas Geological Survey (1892), 371-446.

118 C. H. GORDON

the formation is placed just below the main limestone and the blue
shale series, the line marking the boundary with the Cisco coincid-
ing approximately with the east line of Shackelford County.

The Cisco.—Below the “Albany,” and outcropping to the east of
that formation, is the Cisco, which is composed of sandstones and
shales, with some conglomerates and two or three beds of coal.
Occasional beds of limestones occur in the lower part of the forma-
tion and again near the top. Coal outcrops along the Salt Fork
of the Brazos River west of Graham in Young County, and else-
where to the northeast and southwest. Some of the beds of coal
are associated with limestones, in one case a thickness of two or
three feet of limestone resting directly upon a bed of coal. The
conglomerates consist of sub-angular fragments of flinty blue lime-
stone and chert cemented together by a ferruginous sand. Nodules
and hollow concretions of limonitic iron ore are common. These
conglomerates have been recognized at two different horizons and
in widely separated localities. Their exact relations, however,
have not been clearly defined. In Stevens County the clays are
mostly blue and yellow. Limestones appear at intervals, but these
thin out northward, while the clays show a corresponding increase
in development.

Relation of the‘ Albany” to the Wichita.—When traced northward,
the limestones of both the “‘Albany”’ and Cisco formations diminish
in thickness, while there is a corresponding increase in the inter-
vening beds of shale. In the case of the ‘“‘Albany”’ the limestones
show also a change, becoming more earthy and irregular in their
texture, and some of the beds passing into gray indurated clays.
The few limestones in the upper part of the Cisco formation dis-
appear entirely in the northern part of Young County. Along
with this change there is an increasing development of red clay,
alternating with the blue. The massive beds of limestones con-
stituting the upper part of the “Albany” along the Clear Fork in
northwestern Shackelford County and in western Throckmorton
County were traced northward as far as Beaver Creek in eastern
Wilbarger County. They appear in more or less continuous
exposures as far north as Seymour, north of which they are covered,
but are again exposed, greatly diminished in thickness on Big

WICHITA FORMATION OF NORTHERN TEXAS 119

Wichita River and Beaver Creek in the line of their strike north-
ward. Greater difficulty is encountered in the effort to trace the
lower beds of the “Albany,” owing to the greater proportions of
clays and sands and the disturbed condition of sedimentation, both
conditions becoming more pronounced as the beds are followed
northward. Certain of the limestone beds, however, are persistent,
although showing changes in their physical character, and by means
of these the eastern boundary of the formation was ascertained
with a fair degree of accuracy. At Fane Mountain, a low eleva-
tion in the southeastern corner of Throckmorton County, is an
outcropping of limestone characterized by an abundance of M yalina
permiana. These beds occur at intervals northward in eastern
Throckmorton County, and at Spring Creek in the northwestern
corner of Young County they outcrop in the bank of the river about
a mile from the post-office. Here the beds show locally a gradation
into sandstone suggesting near-shore conditions of sedimentation.
On Godwin’s Creek, in the western part of Archer County, the
diminished representatives of these, or possibly somewhat higher,
beds appear, as also farther north on the Big Wichita River. The
limestone which outcrops on the Big Wichita north of Fulda,
referred to on p. 116, is evidently one of the lowermost beds. The
most northerly appearance of presumably the equivalents of these
beds was noted in the vicinity of Electra in the western part of
Wichita County, where occasional plates of limestone appear over
the surface apparently as a result of the weathering out of lenses
of limestone in the clays. In the case of the Cisco formation the
changes which these undergo toward the North have not had care-
ful study. The limestone, however, appears to thin out entirely
in the northern part of Young County, there being no representa-
tives of these formations in the “‘Red Beds” area except it be the
impure, calcareous nodular beds described above.

Nowhere in the southern area so far as observed are there any
indications of unconformity. Notwithstanding the lithological and
faunal characteristics which distinguish the “‘Albany,”’ these beds
appear perfectly conformable with the Cisco below and the Clear
Fork above, nor is there within the formation any indication of
stratigraphic discordance. The change in the lithological character

120 C. H. GORDON

of the beds toward the north is evidently the result of differences
in the conditions of sedimentation. The character of this part of
the formation suggests very strongly its origin on a coastal plain,
or river delta, to the south and west of which lay the sea in which
were deposited the marine “Albany” sediments. The inter-
relations of the two kinds of sediments suggest oscillation of the
shoreline upon a relatively wide coastal plain. These changes
may be explained as the result of oscillation of the land surface or,
possibly better, by the slow but intermittent sinking of the coastal
region.

As suggested by Case,’ Beede,”? and others, the materials of the
“Red Beds”’ were evidently derived from a land mass on the north,
of which the Wichita and Arbuckle mountains are the remnants.
The following quotation from Beede’s paper is especially pertinent:

The Arbuckle and Wichita mountains are probably the source of much of the
red sediment in which they are partially buried, and the former mountains are
directly responsible for the eastern extension of these beds in central Oklahoma.
The extent to which the lighter colored sediments of Kansas and Texas are
replaced by red sediments in Oklahoma and near it represents in a rough way
the limits of the influence of these mountains on the deposits of the time by
the spread of their sediments. By the time the deposition of the light colored
sediments had ceased the conditions had become such that nearly all the sedi-
ments derived from the land surrounding the basin were red.

FAUNAL RELATIONS

In the course of the field work collections of fossils were made
at many localities, chiefly in the region occupied by the “Albany”
beds. At the close of this paper is given a list of the invertebrate
fossils obtained from the Albany and Wichita areas. ‘The list
includes the collection made by the author, and those made several
years since by Mr. E. O. Ulrich. The localities are indicated on the
map by corresponding numbers. ‘These remains indicate, accord-
ing to Dr. Girty, a marked identity in the invertebrate faunas of
the Albany and Wichita areas. In the collections several different
faunas can be discriminated. One of these has the brachiopod

~E. C. Case, Bulletin of the American Museum of Natural History, XXIII (1907),

659-64.
2 J. W. Beede, Journal of Geology, XVII (1909), 714.

WICHITA FORMATION OF NORTHERN TEXAS 27

element fairly well represented, Derbya cymbula being generally
present, and the pelecypod Myalina deltoidea rather abundant.
Another contrasting fauna has, as a rule, brachiopods absent or
greatly diminished, but is plentifully supplied with large nautiloids.
The faunas appear to have been contemporaneous, both occurring
throughout the formation, but in different localities. The nauti-
loid facies, however, is more prominent in the upper series of beds.

The invertebrate remains of this region were studied by C. A.
White, who considered them to be Permian. A map on which
the localities were shown was prepared for the Fifth Annual Report
of the Texas Geological Survey, but never published.?

The collections of vertebrates, which in past years have attracted
so much attention, were made in the adjoining portions of Baylor
and Archer counties. Cope, who first studied them, considered
them to be of Permian age. A description of the localities where
these remains were discovered has only recently appeared in print.
From this description, which is not accompanied by a map, it ap-
pears that no fossils were obtained east of the middle of Archer
County. In late years interest in the vertebrate remains of the
Wichita formation has been renewed and much new material has
been obtained, more particularly through the labors of Williston
and Case. The results of their investigations have appeared in
varlous papers.

The plant remains from this region have been studied by
Fontaine and White! and by David White. The last named spent
several days in the field in rg09 and collected considerable material
from two near-by localities, one, two and one-half miles south of
Fulda, and the other four miles southeast of that place. As pro-
visionally identified this material is as follows:

tC. A. White, U.S. Geological Survey Bulletin 77 (1891).

2 Transactions of the Texas Academy of Science (1897), 95.

3W. C. Cummins, Journal of Geology, XVI (1908), 737-45.

41. C. White, Bulletin of the Geological Society of America, III (1892), 217-18.
Study based on identifications by W. N. Fontaine.

5 No. 1: Cassil Hollow, two and one-half miles south of Fulda, Texas. No. 2:
Breaks of the Little Wichita, one-half mile south of the river, and four miles southeast
of Fulda, Tex. The beds are just over the bone-bearing limestone. The species
in bold-faced type are characteristic of the Permian.

122 C. H. GORDON

Locality No. 1
Pecopteris arborescens
Pecopteris hemitelioides
Pecopteris densifolia ?
Pecopteris grandifolia
Pecopteris mertensioides ?
Gigantopteris sp. (cf. nicotianifolia)
Neuropteris (cf. lindahli)
Aphlebia sp.

Taeniopteris multinervis
Annularia spicata
Sphenophyllum ? sp.
Sigillariostrobus hastatus
Walchia schneideri ?
Gomphostrobus bifidus
Cardiocarpon n. sp.
Carpolithes sp.

Pelecypods

Estheria and fish scales

Locality No. 2
Pecopteris hemitelioides
Pecopteris grandifolia
Pecopteris candolleana
Pecopteris tenuinervis
Diplothmema ? sp.
Odontopteris fischeri ?
Odontopteris neuropteroides
Neuropteris cordata
Taeniopteris coriacea ?
Taeniopteris abnormis
Taeniopteris n. sp.
Sphenophyllum obovatum
Sigillaria sp. (leaf)
Gomphostrobus ? sp.
Cordaites principalis
Poacordaites cf. tenuifolius
Walchia piniformis
Aspidiopsis sp.
Araucarites n. sp.
Cardiocarpon n. sp.

Insect wings
Estheria
Anthracosia -

Ostracods and fish scales

CORRELATIONS

That the limestone series of Baylor County is the equivalent
of the “Albany” formation of the southern area is fully established
by both the stratigraphic and the faunal evidence. The beds in the
northern area, which include the limestones, shales, and sandstones of
Baylor County and the sandstones and shales of Archer and Wichita
counties, constitute the Wichita formation. Our investigations
therefore fully support the conclusions of Cummins‘? and Adams? as
to the equivalency of the “‘Albany” and Wichita formations.

=W. C. Cummins, Transactions of the Texas Academy of Science, 1 (1897), 93-907.

? George I. Adams, Bulletin of the Geological Society of America, XIV (1903),
TQI—200.

3 Along with the limestones of northeastern Baylor County which Cummins
has designated as the top of the Wichita the writer would include the overlying beds
of shale and limestone mapped by him as Clear Fork, which outcrop in the banks of
the Big Wichita about a mile east of the Seymour-Vernon road and northward on
Beaver Creek.

WICHITA FORMATION OF NORTHERN TEXAS 123

Gould! correlated the Clear Fork with the Enid, Blaine, and
Woodward formations of Oklahoma. In making this correlation,
he evidently followed Cummins’ earlier writings, in which the beds
of Baylor County were considered to be Clear Fork. Williston
states? that the Enid formation of Gould is identical with the beds
of Baylor County.

NOMENCLATURE

In the paper cited, Adams has contended that the terms Wichita,
Clear Fork, and Double Mountain should be discarded as having
no stratigraphical significance. In his latest papers, Cummins
recommends the abandonment of the term Albany and the use of
the term Wichita for the formation. In view of the conflicting
statements that have been made as to the relations of the beds
called Wichita we were at first inclined to agree with the first-
named writer in recommending the abandonment of the term
Wichita. Further consideration, however, leads us to conclude
that with a revised definition it will be best to retain the name
Wichita for the formation overlying the Cisco, which it is now gen-
erally agreed should be regarded as of lower Permian age, and to
abandon the name “‘ Albany.”’

The series of red clays and sandstones with their included
gypsum deposits which in Texas overlie the Wichita formation
and to which the names Clear Fork and Double Mountain have
been given have not as yet received much study. With the limited
amount of knowledge available the attempt to subdivide these
beds seems to the author unwarranted, and they are, therefore, here
mapped as “undifferentiated Clear Fork and Double Mountain.”

CLASSIFICATIONS

The Permian age of the beds to which the name of Wichita was
originally applied has been accepted quite generally, though there
are not wanting those who regard the evidence as unsatisfactory.
It was based chiefly upon the vertebrate and plant remains. In the
southward, or ‘‘Albany,” area the beds are wholly marine and

™C.N. Gould, Water-Supply Paper No. 154, U.S. Geological Survey (1906), 17.

2 Letter to the author dated August 6, 1g09.

124 C. H. GORDON

destitute of both plants and vertebrates, though abounding in the
remains of invertebrates. The Pennsylvanian aspect of this fauna
has strongly impressed some investigators, including the author
of this paper, and doubt was entertained as to whether the plane
of separation between the Pennsylvanian and the Permian should be
drawn at the base or at the top of the formation. The studies of
David White, Beede, and others have contributed much in recent
years to a knowledge of the Permian in American and in the main
support the view of the Permian age of the Wichita formation.
In a recent paper Beedet has ably discussed the Permian of Kansas,
with which he correlates the ‘““Red Beds” of Texas. Cummins
correlates the beds of eastern Baylor County which he regards
as the top of the Wichita formation with the Fort Riley limestone
of the Chase group of Kansas. ‘“‘It is quite certain that the Fort
Riley horizon is the same as the Wichita of Texas and is at the very
top of the division.’ The top boundary of the Wichita formation
was drawn by Cummins? at the top of a stratum of red clay over-
lain by thin beds of limestone and blue shales at a point on the Big
Wichita four miles west of the east boundary of Baylor County.
However, as we have shown, beds which are undoubtedly the same
as those which appear at Seymour and southward in Throckmorton
County appear in the banks of the Big Wichita River some eight
to ten miles west of this point. The thickness of the strata included
here, which overlie Cummins’ topmost beds, and are here included
with them in the Wichita formation, is estimated to be 250 to 300
feet. The whole limestone and shale series of Baylor County,
thus included as the upper division of the Wichita formation, is
provisionally placed at 450 to 500 feet, and consists, as shown
elsewhere, of limestone beds of varying thicknesses separated by
varying but usually great thicknesses of shale.

How much of this is to be correlated with the Fort Riley lime-
stones can be determined only by more detailed stratigraphic and
paleontologic studies. Cummins evidently intended to include

tJ. N. Beede, Journal of Geology, XVII (1909),-710-29; Kansas University
Science Bulletin, 1V, No. 3 (1907).
2W. F. Cummins, Transactions of the Texas Academy of Science, II (1897), 98.

3 Second Annual Report, Texas Geological Survey (1891), 402, 403; also Fourth
Annual Report (1893), 224.

WICHITA FORMATION OF NORTHERN TEXAS 125

the lower beds only in his correlation. It may be that further
studies will show that the overlying beds of the Winfield limestones
of Kansas are represented here.

DISCUSSION BY GEORGE H. GIRTY

The equivalence in a general way of the fossiliferous late
Carboniferous beds of Kansas and Texas has long been recognized
and in both cases they have very generally been cited as Permian.
Cummins,’ partly on stratigraphic and partly on paleontologic
evidence, reached the conclusion that the Fort Riley limestone
of Kansas occupies a position at the top of the Wichita formation
of Texas. The Fort Riley is the middle formation of the Chase
group, the lowest group of the Kansas Permian, so that the bottom
of the Wichita may well be as low as the base of the Permian of
Kansas. This correlation of Cummins is probably the most pre-
cise and the best sustained of any, and it is also in accord with some
recent paleobotanic evidence. Mr. White states in the present
paper in discussing the fossil plants which he obtained from the
Wichita formation that the latter is probably referable to the Chase
group of Kansas.

Not until recently, it seems to me, has adequate evidence been
adduced either for distinguishing the Permian of Kansas and that
of Texas sharply from the underlying Pennsylvanian or for cor-
relating them with the Permian of Europe. C. A. White found
the Wichita fauna to have essentially a Pennsylvanian (‘Coal
Measures’’) facies, in which, however, certain characteristic
Permian Ammonites occur. A similar conclusion seems to be
demanded by the evidence of the present collections.

In all, 75 species have been discriminated in the Wichita collec-
tions which I have studied, the local distribution of which is shown
in the table prepared by Mr. Gordon accompanying the present
paper. The identifications naturally vary in precision and refine-
ment. In many cases it has been possible to name only the genus
to which a species belongs. This is sometimes due to the fact
that the species is undescribed. In a few instances species have
been cited by comparison with others, e.g., Bellerophon aff. harrodt.

« Trans. Texas Acad. Sci., II (1897), 98.

126 GEORGE H. GIRTY

If such citations are included as species identified, 48 species of the
fauna are identified and 27 are unidentified. Of the 48 species
identified, 37 are known to occur in the Pennsylvanian rocks of
the Mississippi Valley. Most of them are cited by Dr. Beede in
his table showing the Pennsylvanian faunas of Kansas. The large
percentage of indeterminata introduces a considerable possibility
of error in the inference that 75 per cent of the fauna of the Wichita
formation consists of well-known Pennsylvanian types, but it is
undoubtedly true that in the main this fauna has a Pennsylvanian
facies. One or two new forms at present excluded from the identi-
fied species would somewhat decrease this percentage. On the
other hand, of the 25 per cent which is not known to occur in the
Pennsylvanian of the Mississippi Valley, relatively few species are
characteristic of the Permian of that area; still fewer, if any,
are characteristic of the Permian of Europe. Some of them occur
in western faunas, probably contemporaneous with the eastern
Pennsylvanian. Bellerophon subpapillosus is one of these. Twenty-
five in a hundred, therefore, far overstates the percentage of char-
acteristic Permian species. Such percentage, however, might be
considerably increased by the inclusion of certain species known
to occur in the Wichita formation but not represented in the Survey
collections. I refer especially to the Ammonite forms described
by C. A. White from the Military Crossing of the Wichita. These
are by all means the most diagnostic Permian types of the fauna.
How little characteristic of it they really are, however, is shown
by the fact that later collections made at the same place fail to
contain them, although a special search was made to secure addi-
tional representatives.

Mr. White finds that.about 50 per cent of the Wichita flora
consists of species characteristic of the Permian, while most of
the remainder are known to occur in rocks regarded as of Permian
age. If we omit the fauna of the. Kansas Permian, to include
which would be a sort of circulus vitiosus, no condition comparable
to this has been demonstrated by the invertebrate fossils and, in
so far as I have seen the evidence, no such condition exists. Iam,
therefore, accepting the Permian age of the Kansas and Texas
beds, but at present strictly on the paleobotanic evidence.

WICHITA FORMATION OF NORTHERN TEXAS Toy,

If the upper part of the Carboniferous section of Texas is to be
discriminated as Permian, the line of division, as indicated also
by the paleobotanic evidence, would probably best be taken at the
base of the Wichita.

An inspection of the faunas collected from the strata immediately
concerned in this report shows a rather noteworthy change of facies
between the Wichita and the Cisco—a change, however, which is
more or less progressive and has its beginning in earlier beds.
This shows itself rather in a limitation than in a change of fauna
and in the prominence of certain groups more rare below. Thus
the brachiopods, pelecypods, gasteropods, etc., are much less in
evidence in the Wichita than in the Cisco, but, as already pointed
out by C. A. White," they are essentially the same as those of the
normal Pennsylvanian fauna. In the Wichita, however, we have
~a remarkable development of the Cephalopoda, which in the earlier
sediments are rare.

Just what significance faunal changes of this sort possess it is
difficult to say. It seems to be a change comparable to that which
is more strikingly illustrated when a thin calcareous sheet with a
marine fauna occurs in the middle of a coal deposit. Here, of
course, there is an absolute change from the animal life of the cal-
careous stratum to the plant life of the coal and roof shale, but in
this case the significance is not ambiguous and it is clearly not
stratigraphic. So I think the faunal change marked by a substitu-
tion of one predominating animal type for another may often be
more safely interpreted as environmental than as stratigraphic in
itsimport. At the same time the stratigraphic significance may be
present also, which would appear to be the case with the Wichita
auna, as indicated by the fossil plants. Nevertheless, this change,
as marking the evolution from one geologic period to another, would
be more impressive if the molluscan and molluscoidean groups
were continued into the Wichita and with a difference of facies
such as is usually found when the faunas of other systems are con-
trasted.

U.S. Geol. Surv., Bull. 77 (1891), 30-39.

2 T mean of course that there is usually no time break and no appreciable change
of fauna in the general region accompanying the phenomenon.

128 GEORGE H. GIRTY

In connection with the correlation of the Wichita formation
with the Permian of Europe, it may be well once again to consider
the use and definition of the term Permian.

As is well known, Murchison correlated with the English ‘‘ Mill-
stone grit”? a series of sandy beds which underlies the typical
Russian Permian, and therefore this series, to which the name
Arta beds or Artinskian was subsequently given, was distinctly
excluded from the original or typical Permian. It has since been
recognized that the Arta beds are not the equivalent of the ‘ Mill-
stone grit,’’ and that the fossils which they contain show affinities
with both the “Upper Carboniferous”? below and the Permian
above. The Artinskian therefore came to be called also “ Permo-
Carboniferous,” and by many writers it is included with the other

-under the name Permian.

While the typical Permian is usually underlain by the sandstones
of the Artinskian, over a considerable and well-defined area a heavy
series of limestones and dolomites has been found to intervene.
This apparently lenticular mass has been called the Kungur-stufe,
and on paleontologic evidence has been by Tschernyschew united
with the Artinsk and included under the term “ Permo-Carbonit-
erous,’ which, therefore, comprises two divisions, the-Arta beds
below and the Kungur beds above.

Now, the propriety of including the original Permian and
‘“‘Permo-Carboniferous”’ in a single group is, of course, a question
quite apart from the nomenclature which should be used, and it is
a question with regard to which one who has not studied the rocks
and fossils in the typical region can hardly render an authoritative
opinion. There seems to be European authority both for exclud-
ing the ‘‘Permo-Carboniferous”’ from the Permian and for includ-
ing it with it, the greater number of writers, it may be, adopting the
latter course.

As for the plants, Mr. White states that “from the paleobotanical
standpoint the Artinsk stage of Russia is clearly Permian.”

My own knowledge of the facts is only that of the library, but
I should judge that the faunal break was greater between the
Gschelian and the ‘‘Permo-Carboniferous” than between the
‘““Permo-Carboniferous” and the original Permian. ‘That is, of the

WICHITA FORMATION OF NORTHERN TEXAS 1209

very varied brachiopod fauna described by Tschernyschew from the
Gschel but a small number of species appear to pass over into the
Artinsk, and I infer that much the same is true of other groups.
Both for this reason and because the Artinsk seems to introduce
a new ‘‘cycle of deposition,” I would be disposed to group the
‘‘Permo-Carboniferous”’ with the beds above rather than the beds
below, not feeling, however, that my opinion on this point deserves
much weight.

Now, while there may be diversity of opinion about grouping
together the ‘‘ Permo-Carboniferous” and Permian, all must agree
that it is bad usage to employ the name Permian in two different
senses, especially for the whole and at the same time for a part.
Although the question is international as well as national, the
proposition to remedy the present unfortunate condition would
come with greater force and propriety from European writers.
To me, personally, it is naturally a matter of indifference whether
the term Permian is used for the series and a new name introduced
for the beds above the ‘‘Permo-Carboniferous,” or used for the
beds above the “‘Permo-Carboniferous” and a new name intro-
duced for the series.. The former alternative has in its favor
the fact of perhaps greater usage; the latter, that it is the original
and authoritative usage. I cannot believe that the unscientific
procedure of employing the term in two senses will continue
indefinitely, and consequently whatever we now do, short of the
fundamental courses just named, must be more or less of a make-
shift. It does not, perhaps, make much difference which method
is adopted in this provisional manner, but as the main object is
to be clear and exact, it has to me seemed the better plan to use
Permian in the original and authentic sense.

It seems to me obvious that the Artinskian and Permian should
be assembled under one division or separated into several, entirely
as the sum of the evidence from all sources dictates. I have not
the personal acquaintance with the beds, their faunas and floras,
their field relations, etc., which would entitle me to an opinion of
my own as to how they should be classified. It seems to be a moot

t Possibly some older name could be revived for the Permo-Carboniferous and
Permian, such as Dyas, as suggested by David White.

130 DAVID WHITE

point whether the Arta beds should be regarded as a separate
division or included with the Permian, and it matters little for
purposes of correlation whether an American writer follows one
group of authorities rather than the other. Personally, I am quite
willing to include them both in a single division of the time scale,
and although believing that propriety would be better served by
retaining Permian for only the upper division, I am willing to extend
that term to cover the entire series because of the usage which it
has received in this sense, but I am not willing, for reasons which
must be obvious, to call the whole Permian and the upper part -
also Permian, and for the sake of precision I have been temporarily
calling the upper beds Permian, the lower beds ‘“ Permo-Carbon-
iferous,” and the whole ‘‘ Permo-Carboniferous”’ and Permian. If,
in my Guadalupian report and elsewhere, I restricted the term
Permian to the supra-Artinskian beds, it was done as a matter
of procedure in nomenclature. I had no opinion of my own as to
the classification of the beds to express or defend, although, if I
had, excellent authority could be named in support of my position.

DISCUSSION BY DAVID WHITE

The plant material collected by myself from the breaks of the
Little Wichita River near Fulda, Tex., is derived from two near-by
localities, both near the middle of the Wichita formation. The
fossil plants previously listed by Fontaine and White from two
other localities, and recorded’ by them as Permian, appear to repre-
sent a mixed flora, one of the localities being under suspicion of
Pennsylvanian age. Neither of the latter two localities was visited
by me on account of the lack of time; but on the basis of informa-
tion received, I am disposed to believe that the stratigraphically
lower beds at Antelope are probably Pennsylvanian.

The identifications given on p. 122 are provisional. Later it is
hoped, when the material will have been increased both geographi-
cally and stratigraphically, a formal report covering the floras of
the ‘Red Beds” will be prepared. The species printed bold-face
in the lists on p. 122 are characteristic of the Permian. They
point somewhat distinctly to the Rothliegende age of the beds.

t Bull. Geol. Soc. Amer., III (1892), 217.

WICHITA FORMATION OF NORTHERN TEXAS 131

All the Old World species in the lists occur in the Permian of -
western Europe, and of the remaining species apparently every one
which is not new is found in the Permian of Kansas. Taeniop-
teris, in simple fronds, is represented by several species character-
istically lower Permian. Other types proper to the Permian are
the Odontopteris form, the genus Gomphostrobus, Annularia spicata,
the Sphenophyllum forms, one of which approaches S. stowken-
bergit, and the scales provisionally referred to Araucarites, while
the presence of Walchia assures a horizon as high as the highest
‘Coal Measures.”

The presence of Gigantopteris, abundant at locality No. 2, is
particularly notable since the genus is not definitely known except
from the coal fields of central and southern China, where it occurs
in beds associated with the coals overlying other terranes which,
on the evidence of their contained invertebrates, have been referred
by the French geologists to the lower Permian. The genus is
certainly close to, if not actually identical with, a form described
from several small fragments from the Permian of the Ural region.

In accordance with the paleobotanical standards of western
Europe, I refer the plants of the Little Wichita in Texas to the
lower Permian, the terranes being probably referable to the Chase
group in Kansas. In this connection it should be observed, how-
ever, that the Artinskian flora of the Urals is essentially Permian,
and that paleobotanists universally agree with the general usage
of the geologists of western Europe in referring the Artinsk to the
Permian.

DESCRIPTION OF LOCALITIES

Notre.—The number at the left is the locality number as given at the head of
the list and indicated on the map. The first numbers following the description of
locality are the Survey permanent record numbers, the second the temporary or
field numbers.

t. Bar-X Crossing, Big Wichita River, three miles north of Fulda Station,
5247 (Gt. 67).

2. Bluff of Wichita River, one mile west of Bar-X ranch house, 5243
(Rt. 20).

3. One mile east of Old Military Crossing, Wichita River, 7025.

4. Two miles north of Wichita River, near Old Military Crossing. 70250.

DAVID WHITE

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WICHITA FORMATION OF NORTHERN TEXAS

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134 DAVID WHITE

. Four to five miles northwest of Old Military Crossing, Wichita River,
70256.
. Near Old Military Crossing, Wichita River, 7025d.
Three miles northwest of Fulda Station, near No. 2, 7026.

8. Four miles northwest of Mabelle Station (section house), 7028.

9. Eight miles southeast of Seymour, 5998 Deep Creek.

to. Head of Godwin Creek in eastern Baylor County, 7031, 70314.

t1. Godwin Creek near county line on Seymour-Archer city road, 5242
(Raazo)

12. One to two miles northeast of Spring Creek, Young County (Rt. 30).

13. One mile west of Spring Creek, 7035 (Gr. 12, Gr. 14).

14. Five miles south of Spring Creek, in Butte, 5216 (Gr. 11).

r5. Seven miles south of Spring Creek, Young County, 5217 (Gr. 15).

16. Rocky Ford, Salt Fork, southeast corner of Baylor County, 5218
(Gr. 9).

17. Quarry bank of Salt Fork, Seymour, 5220 (Gr. 7).

18. West bank of Salt Fork, eight miles south of Seymour, eee (Gr. 35).

tg. Nine and one-half miles south of Seymour, Miller’s Creek, 5221,
5224 (Gr. 34).

20. Buttes, near wagon road, half-way between Throckmorton and Sey-
mour, 7036 (Gt. 32).

21. Three miles north of Throckmorton, 5215, 5227 (Gr. 30).

22. Five miles west of Woodson, Throckmorton County, 5219, 5223,
52220 (Gr: 25, Gr. 26, 'Gr.27)).

23. Fane Mountain, three miles southwest of Murray P.O., 5226 (Gr. 24).

24. Paint Creek, southeast corner of Haskell County, 5245 (Rr. 32).

25. Clear Fork, near southeast corner of Haskell County, 5231, 5232,
5240 ( Birn6, Bin 7 bis):

26. Round Mountain on the Clear Fork, near 25, 5237, 5237@ (Rt. 34).

NOLES SON THE OSTEOLOGY OF THE SKULE, OF
PARIOTICHUS

E. B. BRANSON
The University of Missouri

In the summer of tg10 Dr. S. W. Williston asked the writer to
study the Pariotichus skulls in Walker Geological Museum of the
University of Chicago to see if they would throw any light on some
of the undecided points concerning the osteology of that genus.
The material was fragmentary with the exception of one remark-
able specimen of Pariotichus laticeps Williston, a skull of Parzoti-
chus aguti Cope ?, and the base of a skull of an unidentified species.
Some of the undecided questions were: Are squamosal and pro-
squamosal both present? Is there a distinct quadratojugal ?
What are the homologies of the tabulare, if such a bone is present ?
What are the homologies of the so-called epiotics, quadratojugals
of Case? Is a presphenoid present ? and What is the arrangement
of the bones in the base of the skull ?

The writer’s thanks are due Dr. Williston for the use of the
specimens and for discussions during the investigation.

In a paper published in 1878" Cope gave the name Parvotichus
brachyops to an imperfect skull from the Permian of Texas, and
later in the same paper described a more perfect skull as Ecto-
cynodon ordinatus. As he supposed that the former had the roof
of the skull unsculptured he referred the specimens to different
genera. In 1882 he described Ectocynodon aguti? and in 1888 Ecto-
cynodon incisivus3 In 1896 he referred all of the Ectocynodonts
to Pariotichus and named two more species, P. aduncus* and
P.isolomus.s In the paper where he named the latter he described

t Proc. Am. Philos. Soc., XVII, 508.
2 Tbid., XX, 290.
3 Trans. Am. Philos. Soc., XVI, 290.
4 Proc. Am. Philos. Soc., XX XV, 135.
5 Tbid., XXXIV, 145.
135

136 E. B. BRANSON

Captorhinus angusticeps, which has recently been referred to
Pariotichus by Broom.’ In 1909 Williston described and figured
Pariotichus laticeps.?

Roof of skull.—No separation of the squamosal into two bones
was observed in either Pariotichus or the closely related genus
Labidosaurus. Williston first called attention to this in Labido-
saurus’ and Broom shows no separation in his figures of Pariotichus.4

‘A quadratojugal is present in its normal position in the temporal
region and this bone is also present in Labidosaurus. Its distinct-
ness is not apparent in the type specimen of Pariotichus laticeps
Williston, and was first noted in a specimen of Labidosaurus
recently acquired by Walker Geological Museum, and corroborated
by examination of other specimens. Dr. Case calls an element in
the base of the skull the quadratojugal, but it seems to be a part
of the squamosal. This part of the squamosal is indicated by the
numeral “2” in Fig. 3. In a specimen of Labidosaurus figured
by Williston, this part of the bone seems to be separate, but in
all other specimens examined there is no evidence of separation.
Dr. Williston worked over all of the skulls of Pariotichus and
Labidosaurus in the Walker Geological Museum to see if we agreed
-on this point and we are now in accord in saying that this is prob-
ably not a separate element.

In 1883 in describing Pariotichus megalops, since referred to
Isodectes, Cope said: ‘‘At the extreme posterior angle is a very
small element in contact with the supraoccipital which may be
the true intercalare.’’> In 1896 he figured this bone in Pariotichus
aguit Cope,° and Case? and Broom! figure it in Pariotichus angus-
ticeps Cope. It is present in the form figured in this paper; and
in one or two other specimens of Pariotichus examined by the writer

t Bull. Am. Mus. Nat. Hist., XXVIII, 218:
2 Biol. Bull., XVII, 241-55.

3 Am. Jour. Anat., X (1910), 74.

4 Bull. Am. Mus. Nat. Hist., XXVIII, 218.
5 Proc. Am. Philos. Soc., XX, 630.

6 Am. Naturalist, XXX, Pl. VII.

7 Bull. Am. Mus. Nat. Hist., XXVIII, 194.
8 [bid., XXVIII, 218.

OSTEOLQGY OF THE SKULL OF PARIOTICHUS 137

it is distinctly separated from the parietal, but there is no indica-
tion of it in Labidosaurus. Cope also applied the name tabulare
to the element and recently Broom has suggested the name post-
temporal. ‘There seems to be no valid objection to tabulare and it
has the advantage of priority over Broom’s name.

All writers seem to be agreed about the rest of the bones in the
roof of the shull.

Base of skull.—The bases of several skulls examined during the
investigation were fairly well preserved and the one from which
Fig. 3 was made is almost perfect. This shows the post-parietals
in the same position as figured by Williston in Labidosaurus' and
by Case in Edaphosaurus? and Pariotichus. (Case calls them
epiotics in Edaphosaurus. )

The exoccipitals are large and articulate with the squamosals
after passing in front of the inturned edge of the latter, the quadra-
tojugals of Case. The stapes, tympanic of Broom, articulates at -
its distal end with the lower inner end of the quadrate. In the
drawing it is not shown distinctly separated from the exoccipital,
the sutures not having been determined. ‘The separation in this
form is probably as shown by Williston in Labidosaurus.

The position of the quadrate is almost vertical with a broad
bladelike process above and a heavy expanded portion below.
The bladelike portion projects forward almost parallel with the
median line of the skull, and the posterior end of the pterygoid
rests against it. Its upper end comes in contact with the squamosal
and the outer side of the base touches the quadratojugal.

Floor of skull—The pterygoids extend from near the posterior
end of the skull almost to the anterior end. They meet in the
median line and are not separated by the basisphenoid as shown
by Broom in Pariotichus angusticeps Cope. The sutures between
the long slender palatines and the pterygoids were made out in
one specimen from the anterior end to near the posterior end, as
shown by solid lines in the drawing. There are strong indications
of a transverse as shown by broken lines in Fig. 4, but the evidence

t Amer. Jour. Anat., X, Pl. III, Fig. 4.
2 Revision of the Pelycosauria of North America, 1907, p. 153.
3 Bull. Am. Mus. Nat. Hist., XXVIII (1910), 218.

138 E. B. BRANSON

is not entirely convincing. The presphenoid is perfectly preserved
in one specimen in Walker Geological Museum but is lost in all
others examined. It is slender and extends about half the distance
from the basisphenoid to the anterior end of the skull. ‘The sutures
between the vomers and palatines are not evident in any of the
specimens studied.

In the specimen shown in Figs. 1 and 2, which is probably Partoti-
chus aguti Cope, though it has only two teeth on the premaxillaries,
the teeth on the maxillae are in one row to behind the fifth where a
second row begins inside the first, and behind this two other rather
indistinctly defined rows appear. Nearly all of the teeth are sub-
circular in cross-section near the base, but some of the posterior
ones are more or less compressed laterally.

The distinction between Pariotichus and Labidosaurus made
by Cope, that the latter had the teeth of the maxillae in one row,
breaks down in the Walker Geological Museum specimens. In two
specimens examined during the present investigation a second row
of teeth is evident and in other specimens the preservation is not
such as to show whether there is more than one row.

Mandible.—The dentary makes up the outer part of the anterior
half of the mandible. Just behind the dentary there is a short
coronoid which occupies about one-third of the width of the jaw
and sends upward a very large coronoid process almost equal in
width to the rest of the mandible. Behind the coronoid the angular
makes up most of the outer part of the posterior half of the jaw,
and also sends forward a slender process between the dentary
and the splenial, which reaches almost to the tip of the mandible.
Above the angular and separated from it by a suture that runs
diagonally across the jaw and passes to the posterior inferior corner,
there seems to be a surangular. The splenial is not well preserved
in any specimen observed and all that can be determined is that it
is a broad flat bone on the inside of the jaw. The articular is imper-
fect in all of the specimens, but in a perfect specimen of a closely
allied form, found completely separated from the other bones of
the jaw, it is heavy at the posterior end and sends a long slender
process forward.

emai

foe

URN oct

PLATE [

JOURNAL OF GEOLOGY, VoL. XIX, No. 2

OSTEOLOGY OF THE SKULL OF PARIOTICHUS 139

EXPLANATION OF PLATE
(The figures on this plate are natural size)

Fic. 1.—Top view of skull of Pariotichus aguti Cope.

Fic. 2.—Lateral view of skull of Pariotichus aguti Cope.

Fic. 3.—Base of skull of Pariotichus, species unidentified.

Fic. 4.—Floor of skull of Pariotichus restored from three specimens.

I,parietal; 2,squamosal; 3, postorbital; 4, quadratojugal; 5, jugal; 6, frontal;
7, prefrontal; 8, nasal; 9, maxilla; 10, premaxillae; 11, dentary; 12, angular;
13, coronoid; 14, surangular; 15, tabulare; 16, vomer; 17, pterygoids; 18,
palatines; 19, transverse; 20, quadrate; 21, basisphenoid; 22, basioccipital;
23, stapes; 24, exoccipital; 25, supraoccipital; 26, postparietal. (As the
surface sculpture was not well preserved in any of the specimens no attempt
was made to reproduce it exactly in the drawings.) Lined areas are restored.

HIGH TERRACES AND ABANDONED VALLEYS IN
WESTERN PENNSYLVANIA’

EUGENE WESLEY SHAW
U.S. Geological Survey, Washington, D.C.

The terraces with which this paper has to do are the well-known
gravel-covered rock shelves found along the Allegheny, Mononga-
hela, and other large streams of western Pennsylvania, about 200
feet above present stream channels. The abandoned parts of
valleys are closely associated with the terraces, being found at the
same elevation, and in many places the two are connected. Fig. 1
shows the principal areas of high terrace. The region includes all
the Ohio River basin above New Martinsville, where there was
formerly a divide. There are, however, terraces and abandoned
parts of valleys of the same age on the Kanawha, Guyandot, Big
Sandy, Kentucky, and other streams.

The impressiveness of these features is attested by the long list
of names of eminent men who have studied and described parts
of them. This list includes Stevenson, Leslie, Jilson, Chance,
Wright, Chamberlin, Gilbert, I. C. White, Tight, Canaalell E. H.
Williams, Leverett, and others.

Some of the earliest workers believed that the terraces were
due to a submergence and marine erosion. Stevenson in 1879
(Proc. Am. Phil. Soc., XVIII, 289-316) called attention to benches
along the valley of the Monongahela and its tributaries. He
divided them into a higher series of twenty benches, and a lower -
one of five. The higher series he attributed to marine action.
They are probably entirely above those under discussion, and
later work on them has shown that they are obscure and are
probably due to hard layers of rock. The lower series of Steven-
son seems to include those under discussion, and he refers them to
stream action, without going into details of development.

« Published by permission of the Director of the United States Geological Survey,
Washington, D.C.

140

Fic. 1.—Principal areas of high terrace. Black areas have glacial gravel; those
in outline have local gravel only.

142 EUGENE WESLEY SHAW

In 1883 Professor G. F. Wright presented evidence of a large
ice dam at Cincinnati, and shortly thereafter Professor I. C. White,
in a paper before the American Association for the Advancement
of Science, referred the terrace deposits of the Monongahela to
that dam.

Chamberlin, in 1890 (Bull. U.S. Geol. Surv. No. 58, 13-38),
showed that the upper series described by Stevenson could not be
ascribed to the ice dam, because of their great range in altitude.
He also pointed out certain characters of Stevenson’s lower series
which indicated that they were of fluviatile, not lacustrine, origin.
These characters were: (1) the terraces slope with the present
streams; (2) the material capping the terraces is distinctly fluvial;
(3) they are rock platforms; (4) the form and distribution of the
terraces is of fluvial, not lacustrine, order; (5) the abandoned
channels must have been of stream origin.

In 1896 Professor White expressed himself (Am. Geol., XVIII,
December, 1896, 368-79) as still convinced that the glacial
lake, Monongahela, did exist and was responsible for the terrace
deposits, but that the ice dam was probably not at Cincinnati,
but in the vicinity-of Beaver, Pa.

In the Masontown-Uniontown folio, published in 1902, M. R.
Campbell advances the theory that the deposits and abandoned
channels are due to local ice dams which formed in Kansan time.
He points out the fact that it is an extremely difficult and slow
process for a stream to cut off any of its meander in a rugged region
like Pennsylvania, and that it is impossible for a stream to establish
a totally new course unless the conditions under which it operates
are very different from those which normally affect the develop-
ment of streams.

Again, as an objection to the view of Professor White, Mr.
Campbell states that while it would be possible for a stream to
change its course by superimposition if it were first caused to silt
up its valley and then permitted to cut down again, he finds that
part of the Carmichaels abandoned channel was not so silted up,
and he therefore concludes that the change of course was not due
to silting up and superimposition, but to local causes. Mr. Camp-
bell’s idea is that ice jams formed in glacial time and that these

TERRACES AND VALLEYS IN WESTERN PENNSYLVANIA 143

grew until they formed huge dams too or more feet high, and that
they persisted until deposits over 100 feet thick accumulated above
them. In many cases these dams not only gave rise to terraces
but caused the rivers to abandon their old valleys and cut new
ones.

In the Amity folio Frederick G. Clapp expresses the belief that
Professor White’s theory—that of ponded waters throughout much
of western Pennsylvania—will best account for the phenomena.
He states that the upper limit of the stream deposits in all the val-
leys of southwestern Pennsylvania and parts of adjacent states
has a vertical range of but little over 100 feet, but since Mr. Clapp’s
work was published the gravel has been found to lie at an elevation
of over 1,200 feet on Clarion River, making the vertical range more
than 200 feet. .

The data gathered by the present writer, instead of lending
support to any one of these views, seem rather to indicate that the
high terraces and abandoned channels on all the rivers developed
as a unit, through the overloading of the Allegheny in early glacial
time.

The terraces may be divided into two groups, which have certain
essential differences. Those of the first group are capped with
glacial gravel, and are found along the Allegheny and Ohio. Those
of the second bear material of local derivation, and are found on
streams tributary to the Allegheny and Ohio. There are other
differences which will be brought out later. In this connection
it should be stated that there are a few remnants of older gravels,
which lie at various elevations above the main high terrace forma-
tion, and in some places have been let down by erosion, so that they
seem to connect with the much more extensive deposit below, but
the older gravels have very slight extent.

TERRACES OF THE ALLEGHENY AND OHIO

The terraces of the Allegheny and Ohio are almost continuous
from the mouth of the Clarion to Pittsburgh, and on down the
Ohio. The gravel deposits on them are thin or absent where crossed
by lateral streams; in other words, where erosion has been most
severe; but enough remains to indicate clearly the position of the

144 EUGENE WESLEY SHAW

original upper surface. At over one hundred places the upper
limit of gravel has been determined by level, and that limit is in all
cases very nearly 300 feet above present low water. ‘The eleva-
tion of the rock floor beneath the deposits has also been determined
at many points, and is found to be a little less than 200 feet above
the present position of the rivers. Thus, the upper limit of gravel

TABLE SHOWING ELEVATIONS OF HIGH TERRACES IN WESTERN

PENNSYLVANIA
: 2 Upper Limit
Place sale from Wap Tent eck oon | Beets ec ee
ent Stream.
Foxburg quadrangle
*One mile north of Callens-
Ueto nual saree IIo 1,180 1,160+ 970 230
> Rurnipholese a nee 108 1,170 I,120— 930 240
1,160
Mouth of Clarion River.... 102 I,150 1,035 846 304
Mouth of Bear Run ....... 99 1,145 LOZ Gini moAO 305
Montene yas: ion wa steiner: 96 1,140 THOUS) |e O32 308
Kittanning quadrangle
Redbank san cms sanieicnes 81 . 1,100 950 810 290
sHorde@ityaiGe ssc voce ee 538 1,025-+ 885 763 262+
and
980
New Kensington quadrangle
Wharentum Ge snr ane arS 30 1,000-+- 075 725 Onis a
Carnegie quadrangle | |
INIFANS N55 obo ob abu oo sos 22 T,000 896 698.4 300-+
Beaver quadrangle
BeaVviersna city ie ° 978 goo 672 306
Latrobe quadrangle
*One mile northeast of |
Blairsville eee 80+ | 1,060 sim goo 160
Burgettstown quadrangle
*One and one-half miles
northeast of Burgettstown 28+ 1,028 1,015 047 81

*Gravel of local derivation (not glacial).

falls regularly from 1,145 feet at Foxburg to 1,010 feet at Pitts-
burgh; the rock floor beneath the gravel from 1,015 to about 880
feet, and the river from 845 to’7oo feet. Here, then, are three
approximately parallel planes, each of which slopes about 140
feet in 80 miles. In other words, the gravel formation holds its
thickness of about 125 feet, and slopes in the direction of present
stream flow. See table.

The pebbles are well rounded, and lie in a matrix of sand and

TERRACES AND VALLEYS IN WESTERN PENNSYLVANIA 145

clay, though in some places there is so little fine material that the
gravel is dug from pits and used without further washing. In
such places beds of gravel are separated by lenses of clay, but on
the whole the formation is homogeneous.

That the deposit is of fluviatile and not lacustrine origin seems
to be shown decisively by the characters to which Chamberlin
has called attention: The deposit slopes regularly with the present
streams throughout their winding courses. A lake deposit would
be horizontal unless affected by crustal deformation, and in that
case the slope would not change direction at just the places where
the course of the river changes. Second, the material is distinctly
fluvial, consisting of irregularly bedded gravel which contains
lenticular masses of silt and clay. A lake deposit in a valley might
have deltas containing some coarse material, but in no way could
coarse glacial débris, poured into the end of a narrow lake too or
more miles long, be evenly distributed so that the resulting forma-
tion throughout its length would be homogeneous and of uniform
thickness. A

‘There seems to be good evidence also, as Leverett has pointed
out, that in pre-Glacial time the Clarion was the headwater portion
of the Allegheny, a divide crossing the present course of the latter
stream just above the mouth of the former, and that the glacier,
by. cutting off the outlets of the drainage of the area to the north,
forced the water to cut across the divide to the old Lower Allegheny,
thus thrusting greatness upon the Allegheny basin.

Through the new cut were discharged great volumes of glacial
outwash—too great for the Allegheny to transport—and_ the
coarsest part of the débris was spread along the bottom of the valley,
forming a typical valley train which had a nearly uniform thick-
ness throughout its length. The bodies of gravel on the high
terraces of the Allegheny and Ohio, then, are the remnants of this
old valley train.

‘The overloaded condition of the Allegheny was probably due
to several causes, among which the following may be mentioned as
being more or less effective: First, an actual increase in load
derived from (a) material fed more or less directly to the streams
by the glacier; (b) débris from the cutting of new gorges across

146 EUGENE WESLEY SHAW

old divides; (c) material brought after the ice melted, by tributaries
as they cut new valleys. Second, a decrease in velocity and carry-
ing power, produced by (a) the attraction of the ice mass; within
a degree of the ice front this may so have changed water level that
in a stream flowing away from the ice a gradient of 1? feet per mile
might have been reduced to 13 or 14 feet per mile; (0) crustal
deformation, due to the weight of the ice; (c) the divides crossed;
each of these would check the velocity and cause deposits for a
short distance upstream; and ice jams operate in a similar way.
Third, a possible but not probable decrease in volume, arising from
a change in climate. It is probable that during Kansan time the
river had a larger volume than now because it was carrying the
run-off from a much larger territory.

TERRACES OF TRIBUTARY RIVERS

The second group of high-terrace deposits is found on streams
tributary to the Allegheny and Ohio. Those along the Clarion
River may be taken as typical and described in detail.‘ At Fox-
burg the high gravels of the Clarion connect and mingle with those
of the Allegheny, both the rock floors and the upper surfaces of the
deposits connecting, without interruption (see Fig. 3). The Clarion
gravels are much like those of the Allegheny, but differ from them in
the following respects: First, the material is of local, not glacial,
origin. Second, the thickness decreases upstream. Third, the
gravels are as a whole much finer, only the base being as coarse
as the glacial gravels. There are some minor points of dissimilarity,
but these are the important ones in the present discussion.

In present distribution the gravels are as continuous as those
of the Allegheny. There is scarcely a half-mile of the lower part
of the valley where they are absent or even approximately so.

That the Clarion terraces are of stream origin is shown by char-
acters similar to.and as decisive as those of the Allegheny terraces
mentioned above, and certain important features indicate the imme-
diate cause of the accumulation of gravel. First, at the confluence
of the two rivers the high-terrace gravels correspond exactly in
elevation and thickness. Second, the Clarion gravel rises and

* See Foxburg-Clarion folio, U.S. Geol. Surv. (in press).

TERRACES AND VALLEYS IN WESTERN PENNSYLVANIA 147

becomes thinner and narrower upstream, and at a distance of 20
miles from the Allegheny the formation has the width, thinness,
and coarseness of an ordinary flood-plain deposit.

These facts suggest at once that the Clarion terraces owe their
existence to conditions on the river into which that stream dis-
charged. When the Allegheny began to aggrade, the effect was that
of a gradually growing dam across the mouth of the Clarion. This
caused the latter stream to drop the coarsest part of its load. The
dam did not grow so rapidly as to produce a pond in the river above,
but aggradation kept pace with the growth of the dam. In other
words, at its mouth the Clarion built up as rapidly as the Allegheny.
This is shown by the even downstream dip of the Clarion gravels
and by their coarseness. If any ponded stage had existed, the
deposit would have been coarse only at the upper end of the pond
and would have taken the form of a delta.

But of course the dam did not affect the Clarion throughout
its length. On the contrary, when the dam began to grow, its
influence was felt only in that part of the stream immediately
above. As it grew the area affected by it extended farther and
farther from the Allegheny and the river built up to a new gradient,
over which it was just able to carry its normal load. The coarser
part of the gravel was dropped where the gradient changed from
the old to the new. This point gradually moved upstream and the
extended coarse deposit became the basal coarse part of the forma-
tion. The Clarion then silted up because its master stream, the
Allegheny, was aggrading, and the elevation of its outlet was being
raised. The Allegheny aggraded because of great increase in load,
the Clarion because of decrease of gradient. The absolute load of
the latter stream has not changed materially since the dawn of
the Quaternary period.

Space will not permit of complete description of all the high
terraces, but the work of the Clarion may be taken as a type of
the work of those streams which discharged into the overladen
Allegheny and Ohio. Redbank Creek, the Conemaugh, Kiski-
menitas, Youghiogheny, and Monongahela show similar characters.
On all except the smallest of the tributaries of the Allegheny, there
are deposits connecting with the early glacial valley train, such

148 EUGENE WESLEY SHAW

deposits rising, thinning,.and narrowing upstream, and consisting
of mixed coarse and fine material of local origin, the proportion
of fine being somewhat greater. than in the valley train. The
larger the tributary the more gradually does the deposit rise and
thin, for the larger streams have less fall, and there is less difference
between the old gradient, with which the streams were more than
able to carry their loads, and the adjusted gradients, with which
the streams did neither cut nor fill.

To illustrate, certain facts indicate that in pre-Glacial time the
lower 50 miles of the Monongahela had a fall of about one foot

Fic. 2.—Longitudinal section of deposit on a stream tributary to one which is
overloaded with glacial débris. A distinguishing character of such deposits is that
they are definitely limited upstream by the convergence of the old profile in use
when the stream was cutting down, and the adjusted profile with which the stream
is just able to carry the load delivered to it by headwaters and side streams.

per milé, that the adjusted gradient was about g inches per mile,
and that the valley train athwart the mouth of the river was about
t1o feet thick. At this point the Monongahela fill should have
been tio feet thick, and this thickness should have decreased
upstream by 1 foot minus 9 inches, or 3 inches per mile, and at
50 miles the formation should have been thinner by 130 inches,
or 125 feet. The results obtained by actual observation in the
field accord very closely with these figures. The deposit is nearly
too feet thick at the West Virginia line.

As another example, the Clarion gravels thin almost 50 per
cent in 1o miles. Originally, as indicated by the base of the
gravels, the stream had a fall of about 125 feet in the lower 10
miles of its course. The adjusting of the gradient reduced this
to 60 feet. The difference between these figures, or 65 feet, plus
the thickness of the deposit at the upper end of the ro miles, or
50 feet, is 115 feet, which is the thickness of the deposit at the lower
end of the valley.

TERRACES AND VALLEYS IN WESTERN PENNSYLVANIA 149

To sum up, the inferred history of the terraces reads about as
follows. The Allegheny was overloaded at a certain point. The
material was spread out evenly from the place of overloading.
On each tributary stream deposits accumulated, first at the point
of junction with the overloaded one, then farther and farther
upstream. ‘These processes continued until the load and gradient
of the Allegheny were so adjusted that the river was able to carry
its load. Later, probably on account of an elevation of the land,
the stream has cut through its deposit and 200 feet below the level
of the old rock floor.

‘““ABANDONED CHANNELS”’

In close association with the high terraces are the many so-called
abandoned channels or side tracks to the main lines of drainage.
Examples are found not only in western Pennsylvania, but along
the Ohio, Mississippi, and a large number of tributary streams.
Genetically these features seem to be similar, though some devel-
oped early in the Quaternary period and others later.

The abandoned part of the Monongahela valley at Carmichaels,
Pa., referred to on p. 142, has been described as containing evidence
of a huge local dam of ice, but to the present writer the evidence
did not seem to indicate a local barrier for the following reasons:
(1) The deposit thins at the position of the supposed dam not
abruptly, but irregularly, and a mile or more below considerable
thicknesses are found. (2) Just below the place of thinning, the
formation extends up the valley side to the altitude of the upper
limit of gravel, and a little farther away are extensive bodies of the
deposits, fully roo feet thick. (3) The thinner parts are found
at a place where erosion has been very severe—where the gravel
has been dissected by a good-sized tributary. It appears, therefore,
that the thin part of the deposit is simply a result of irregular clear-
ing-out of the old valley by the tributary and is a feature to be
expected. The stream seems to have cut down quickly through the
silt and gravel, but when it came to hard rock it hesitated, mean-
dered a little, and then cut down farther, leaving the shelf covered
with pebbles and bowlders concentrated from the original deposit.
The fact that just below the site of the dam the formation is found

150 EUGENE WESLEY SHAW

today extending up on the side of the valley and a few miles away
the full thickness of over too feet is present, is evidence that the
deposit was formerly roo feet deep here as it is elsewhere. There
could scarcely be any other possibility except that the valley-side
deposit represents an older fill, and there is no foundation for such
an assumption.

A theoretical consideration of the question of local ice dams
yields interesting results. The possibility of an initial ice jam
is not to be questioned. Moreover, the supposition that such a jam
might be large in a northward or iceward flowing stream in a
subglacial climate is reasonable and is supported by known con-
ditions on the McKenzie and other streams which work under
somewhat similar circumstances.

But the ice dams in this case must have been several times as
high as the highest known and must have persisted through many
summers warm enough to melt back the thousands of feet of ice
in a continental ice sheet. Indeed if we assume that the Monon-
gahela carried the same amount of suspended matter which it
carries today (in all probability it did not carry so much), that all its
load of undissolved matter was dropped, and that immediately after
the reservoir became filled the dam went out, we get a minimum
estimate for the life of the dam of about 1,000 years. If only a
quarter of the material were dropped the time would be 4,000 years.

During this time the run-off of the basin must have passed over
the dam, for if the dam had suddenly risen above the height of cols
in near-by divides, the lake immediately behind the dam would
not have been silted up. Moreover, considerable coarse material
is found just above the supposed dam, indicating that there were
strong currents and that only a small fraction of the suspended
matter was dropped.

The hypothesis of an ice dam, therefore, involves the assump-
tion that the Monongahela, which since early glacial time has,
with a very low gradient, removed rock material to a depth of 200
feet for more than too miles, was for centuries unable to cut through
or undermine these blocks of ice over which its gradient and eroding
power must have been that of a cascade or waterfall. The
assumed floor of the valley below the site of the dam is 60 feet below

TERRACES AND VALLEYS IN WESTERN PENNSYLVANIA 151

the top of the fill above the dam. The drop in water level must
have been as great or greater, and yet the dam must have withstood
the pressure and the wear year after year for thousands of years.

Parker oxbow.—One of the most famous of the abandoned val-
leys is the old oxbow at Parker’s Landing (see Fig. 3). It was
first described in detail by Chance (Second Geol. Surv. of Pa.,
Rept. VV, 1880, 17-22). He calls attention to the disproportion-
ate size and breadth of the valleys of the two small streams
which now flow from the oxbow, and also to the fact that between
the heads of the streams there is low swampy ground. Glacial
gravels of probable Kansan age are found almost continuously
around the loop and in some places the deposit is over 50 feet
thick. Chance inferred that at the time of the earliest ice advance
this oxbow was occupied by the Allegheny River, and at a subse-
quent time the neck was severed.

G. F. Wright held that this channel was formed and abandoned
before glaciation, and that the glacial material now found in the
oxbow was deposited there at a time when the Allegheny, being
overloaded with Kansan outwash, aggraded up to a position some-
what above the oxbow; that the gravel was carried into the ends
of the loop, but the river never reoccupied the entire loop. Wright
has long advocated the idea that the Allegheny was cut to about 50
feet below its present channel in pre-Glacial time, and that the
glacial valley train was thus about 350 feet thick, filling the inner
gorge and part of the broad valley above.

Chamberlin and Gilbert studied the problem in 1889, and
their conclusions agree essentially with those of Chance, and are
found in Bulletin U.S. Geological Survey No. 58, 31.

In 1894 Wright again published a paper (Am. Jour. Sci., 3d
ser., XLVII, 173-75) in which he holds to his previous conclusions.

In 1900 E. H. Williams presented a paper at the Albany meeting
of the Geological Society of America (Bull. G.S.A., XII, 1900,
463) in which he agreed with Wright that the river has not
occupied the oxbow since the beginning of the Glacial period, but
he went so far as to hold that the river never did flow around the
so-called oxbow. He ascribes the feature to the work of two
small streams which “rise on opposite sides of a low col and de-

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TERRACES AND VALLEYS IN WESTERN PENNSYLVANIA 153

bouche into the Allegheny gorge within a mile of one another,
and in Glacial time these two valleys were filled by overwash
deposits mingled with material from the immediately adjacent
slopes.” He states also that the rock floor of the abandoned
channel is not level, but falls down rapidly toward the river.
He does not, however, explain the fact that the col between the
heads of the two streams is low and swampy, whereas there is not
a case of two large streams rising in an area of swampy ground in
the whole unglaciated area of western Pennsylvania, and he says
nothing about the broad steep-walled valley through which the
small streams flow.

Frank Leverett (U.S. Geol. Surv. Mon. 41, 242) considers
EK. H. Williams’ view ‘“‘more consistent with the features than the
one presented by Chance,” and says further (apparently misinter-
preting Williams’ view): “It refers the opening of the double
channel, resembling the forks of an oxbow, to a shifting of a smaller
tributary of the Allegheny from one side to the other of a low hill
that stood nearly opposite the point at which the tributary entered
the valley.”

The data gathered by the writer indicate, first, that the so-called
Parker oxbow is an abandoned channel of Allegheny River, and so
is properly called an oxbow. ‘The characters which force such a
conclusion are: (a) the depression has the size and shape of the
Allegheny valley, having a comparatively uniform width of about
a mile, and bounding walls from roo to 300 feet high; (6) the shape
is a broad smooth curve with the side of the valley inside the loop
gently sloping, and that outside high and steep like the present
valley around curves of the river (it resembles, for example, the
curve of the Clarion 1 mile south of Turniphole, Foxburg quad-
rangle); (c) a current with something like the strength of a river
must have flowed around the bend, for pebbles up to 6 inches in
diameter are found at the most extreme part of the loop.

Second: The abandoned channel was occupied in a part of
Kansan time. The presence of Kansan outwash on the floor,
which is at nearly the same elevation as the floor under Kansan
material near by, indicates that the last great event before the
abandonment of the oxbow was the advance of the Kansan ice

154 EUGENE WESLEY SHAW

sheet. The abandonment took place before the stream began
again to cut down, for deposits are found around the loop almost
as high as the highest gravel. The broad valley around the oxbow
was cut previous to this time. One can only conjecture how long
a period of time was necessary for this.

There is some evidence that the rock floor of the east end of the
loop is higher than the Parker strath. If this be true the oxbow
must have been developed either in pre-Kansan time, before the
stream had cut as low as the Parker strath, or after the Allegheny
had aggraded until it was high enough to take this route. How-
ever this may be, the close association of the abandoned channel
with the high terrace, and the occurrence of Kansan material in the
channel, show that whenever it was formed, it was occupied and
abandoned in Kansan time.

Third: The length, depth, and narrowness of the rock channel
through which the river now flows across the neck of the oxbow
suggests that the oxbow was not cut off in the way that streams
ordinarily cut off their meander, but points rather to superimposi-
tion. The present valley across the neck of the abandoned channel
is a narrow rock gorge over a mile long, and the top of the gorge
extends up to the level of the highest part of the old channel.

Another abandoned valley which is thought to show the method
of development very well is found on the Allegheny, a few miles
northeast of Pittsburgh, and opposite Verona. The topography
suggests at once that this feature is a cut-off loop of the Allegheny,
and it is found on a level with the high terraces. The width is
nearly as great as that of the old valley of the Allegheny, and glacial
gravels are found in it. But on closer inspection it is found that
the width of the valley and the thickness of the deposit decrease
rapidly away from the present course of the river, and this through
a rise in the rock floor. Also there is an impressive amount of
fine material and a scarcity of bowlders. Finally, at the extreme
end of the loop the old valley, if such it be, is very narrow, and the
deposit but a few feet thick.

The meaning of these features seems quite evident. At the time
the Allegheny began to aggrade, the position of this loop was occu-
pied by two small tributary streams. The divide between them

TERRACES AND VALLEYS IN WESTERN PENNSYLVANIA 155

was, at one place, a little less than 100 feet above the river-valley
floor. As the river rose it dropped some coarse materials in the
ends of the tributary valleys, but a mile away the ponded water
was quiet and the deposit fine. This process continued until the
Allegheny reached the elevation of the lowest point in the divide
between the streams, about 3 miles away. Then the river current
was separated and a part flowed slowly up one tributary and down
the other, carrying some coarse and much fine material (varying
from season to season) and shaping the col into the form of a
valley. Finally the river cut down again, abandoning the course
which it had occupied temporarily for the much shorter original
course. .

A part of the history of the loop is reflected also in its present
drainage. When the river left it, the run-off was naturally in the
direction in which the river had flowed, out one arm and back
down the other. But a new small tributary in the position of the
upper one of the old ones is now cutting back into the upper end
of the abandoned valley, driving the head of the other stream back
and annexing a part of its unnatural drainage basin.

All of the other abandoned parts of the valleys of this region
have been examined carefully and seem to have been developed
in the same way—by silting up and redissection—and the process
is the same whether the case be on the Allegheny or on one of the
tributary streams. In many cases the new courses made available
by the silting-up of the old channels were about as direct as the old,
and in certain of such cases the stream cut down in its old course,
while in others it assumed a new course. Thus some of the aban-
doned valleys mark courses temporarily occupied by the rivers,
while others show old and long-used courses. It is a significant fact
that the changes were, in nearly every case, from a longer route
to a shorter one. This would scarcely have been true had the
rivers been driven from their courses by ice dams. ‘There are some
cols which stand just a few feet higher than the highest gravel,
and these were, of course, never crossed by the rivers. Indeed,
if aggradation had proceeded 50 or 100 per cent farther there would
have been an amazing network of long and devious “‘abandoned”’
valleys.

156 EUGENE WESLEY SHAW

SUMMARY

Summarizing, the method of development of the high terraces
and abandoned parts of valleys of western Pennsylvania seems
to be as follows: (1) The development of a valley train over 100
feet thick, along the Allegheny and Ohio; (2) from the beginning
the aggradation of this stream produced an effect felt on every
tributary, and a portion of each, beginning at its mouth and extend-
ing gradually upstream, became silted up. (The lower end of
each tributary valley thus took on a form resembling the half-
filled character of the valley of the master stream.) (3) As the
rivers built up they found themselves flowing at the height of one
after another of the lowest places in near-by divides, and at such
times and places the currents were divided and the cols were occu-
pied. This overloaded condition of the streams lasted a long time
and there were many fluctuations, for at some places, as at Pitts-
burgh and Belle Vernon, there are two or three well-developed
valleys side by side. (4) When final redissection began, the
rivers chose the channels momentarily most desirable. In most
cases the short route was the principal factor in the choice, but
in others the largest current at the time and other comparatively
trivial conditions determined the courses of the streams. As in
all cases of superimposition, the resistance of underlying rock
played no part in their location, and at many places the rivers
soon found themselves sawing into hard rock where near by were
courses through unconsolidated materials.

REQUISITE CONDITIONS FOR THE FORMATION OF
ICE RAMPARTS

WILLIAM H. HOBBS
University of Michigan

In a recent paper’ Mr. J.B. Tyrrell, late of the Geological Sur-
vey of Canada, has made the assertion that though he has now for
many winters made observations on and about the Canadian
Lakes, he has never detected any evidence of ice push against
shores as a result of expansion. He thus discredits the accepted
explanation of ice ramparts. To one who has in other localities
seen the ramparts 7m process of formation from this cause, it seems
important to supply an explanation for the failure of such an expe-
rienced and careful observer as Mr. Tyrrell to observe the same
phenomenon.

The quite obvious fact is that ice ramparts are greatly restricted
in their occurrence, a number of special conditions being essential
to their formation. Mr. Tyrrell’s paper fortunately shows that
some of these conditions were lacking in the districts which he
studied.

In order that these requisite conditions may clearly be under-
stood, it will be necessary to give in brief outline the theory of
formation of normal ice ramparts through ice expansion. The
initial ice cover of the winter season on our northern lakes usually
forms with only moderately cold air temperatures. These may
be assumed to be but a few degrees below the freezing point, and
the cover, once formed to a thickness of an inch, grows quite slowly
from the under surface. After it has acquired a considerable
thickness, the arrival of one of the ‘‘cold waves” contracts the ice
cover by lowering its temperature through contact with the colder
air layers. Under this contraction fissures open in the ice to the
accompaniment of loud rumblings, water rises to fill them and is

1J. B. Tyrrell, “Ice on Canadian Lakes,” Trans. Can. Inst. (1910), IX, 1-9
(reprint), pls. 1-6.

157

158 - WILLIAM H. HOBBS

quickly frozen in the prevailing low temperature so as to form
intercalated “‘planks” of younger ice. The lake cover is thus
again completed at a low temperature, so that a ‘warm wave,”
if it can quickly communicate its temperature to the ice, causes an
expansion which according to Tyrrell amounts to one to three
inches per mile per degree Fahrenheit. Thus expanded the ice
cover is too large, and a push is exerted against the shore zf the
cover 1s a structure competent to transmit the stresses induced in tt.
The range of action of this push, and the consequent size of the
ridge raised upon the shore will depend upon the number of times the
process is repeated; for each alternation of “cold”? and “warm”
wave introduces a new series of wedges into the ice cover and
correspondingly extends its margins.

To recapitulate: (1) there must be a wide and probably also a
relatively sudden alternation of lower and higher air tempera-
tures over the lake: (2) these temperature changes must be |
promptly communicated to the ice; (3) the ice cover regarded as
a girder must be competent to transmit the stresses to the shore;
and (4) for large effects the alternations of temperature must be
several times repeated. Obviously, also, the shores of the lake
must be of such form and materials as to be subject to movement
under stresses below the crushing strength of the ice itself.

The first and last conditions are meteorological and can be
determined for any given district. Not only is a severe winter
climate essential, but there must be an alternating occurrence of
cold and warm waves.

The second and third conditions are crucial. In Buckley’s
studies of ice ramparts at Madison, Wisconsin, the most thorough
that have been made,’ it was found that ramparts seldom formed
during seasons when the lakes were snow covered. The probable
explanation of this is that snow blankets the ice and prevents a
quick communication to it of the air temperatures above the snow
surface. We have here emphasized the element of time, for the
reason that studies in Greenland show that air temperatures are
slowly communicated downward through snow blankets to very

tE. R. Buckley, “Ice Ramparts,” Trans. Wis. Acad. (1901), XIII, 141-62; pls.
1-18 (discussion by C. R. Van Hise).

THE FORMATION OF ICE RAMPARTS 159

considerable depths. It is well known from studies of the “fatigue”
of materials under stress that they often yield to slowly acting
stresses that would be transmitted undiminished in intensity if
quickly applied. Snow blanketing of the ice, from the evidence
in Mr. Tyrrell’s paper, would appear to be very general within
the districts which he studied.

Further limitations upon the formation of ice ramparts are
imposed by the third condition—the incompetency of the ice
cover as a transmitter of stresses. With the ice serving as a strut,

Fic. 1.—Sketch map showing the position of ice ramparts and of buckled ice
ridge formed on Lake Mendota at Madison, Wisconsin (based on Buckley’s Map).

its push can be transmitted effectively only when the cover 1s main-
tained as a plane surface. Lack of homogeneity or of absolute
uniformity in strength, and variation in form of the surface at
which stress is applied, will with increasing length of beam intro-
duce an important stress component tending to buckle the beam
and dissipate the energy transmitted by it—the competency of a
strut to transmit stresses is inversely as its length. Experience
shows that lakes or arms of lakes which are much over a mile and
a half across do not develop important ice ramparts. On Lake
Mendota at Madison, the best ramparts are found upon the shores
of University Bay, which is about three-fourths of a mile across.
Outside this bay the lake ice is raised each winter into a sharp

160 WILLIAM H. HOBBS

ridge extending from the outer margin of the bay (the peninsula
of Picnic Point) across the wide portion of the lake to the opposite
shore, and about this section no ramparts are developed (see
Fig. 1).

Ice ramparts can thus form only on shores of lakes which have
relatively small size or on small bays of larger lakes, though
a width of at least half a mile is probably necessary in order to
secure sufficient dilatation of the ice cover to make ramparts of
appreciable size.

Anything which tends to deform the ice cover from a perfect
plane will effectively destroy its competency as a girder, and then
no ramparts will form. Mr. Tyrrell has shown in his valuable
paper that young lake ice will support, without bending, less than
its own thickness of dry snow, and that the ice on Canadian lakes
is bowed down under its load of snow to such an extent that water
comes to the surface through cracks and further increases the
bending.

To sum up, the heavy snow cover alone would by blanketing
the ice, but probably even more by bending it, effectually prevent
the formation of normal ice ramparts. As already stated, such
ramparts may actually be seen in process of formation during a
warm wave in any favorable winter about Lake Mendota at
Madison, Wisconsin.

It is fully realized that rafts of floating ice drifted by the winds
at the time of the spring “break up” do also produce small bowlder
ridges on shores which bear a close resemblance to some of the
types of normal ice ramparts.

THE TERMINAL MORAINE OF THE PUGET SOUND
GLACIER

J. HARLEN BRETZ

I. GENERAL CHARACTER OF THE COUNTRY SOUTH OF PUGET SOUND

The region of Puget Sound, inclosed between the Olympic
and Cascade ranges, is a heavily drift-covered lowland. The drift
is deeply incised by broad valleys of meridional trend, some occu-
pied by arms of the Sound, some by lakes, and others by streams.
The summits of the plateaus and hills of drift accord in a general
level so that, seen from overlooking mountain peaks, the region
appears to be a vast plain, interrupted only by a few rock hills,
remnants of the preglacial topography rising above the drift.

Immediately south of the Sound the drift assumes a different |
facies. The trough valleys disappear and the plain becomes
continuous and is widely covered with gravel outwash. It is
still a part of the great Puget Sound drift plain. It is diversified
with morainic eminences occasionally, of a character different
from that of the drift hills lying between the valleys of Puget
Sound farther north. The most southerly extended of these hills
is a belt which constitutes a part of the terminal moraine of the
Puget Sound glacier.

Beyond the southern portion of the Puget Sound depression
is an abrupt transition in the topography. Rock hills of pre-
glacial sculpture, lying beyond the limit of glaciation, begin here
and continue:southward past the Columbia. In western Washing-
ton no other such area of low rock surface occurs as must here
exist beneath the heavy drift mantle of Puget Sound.

On the southeast, the area is overlooked by the magnificent
Tertiary volcano Rainier. On the south is a region of rock hills
bearing no group name. They are drained by the upper Des
Chutes and the Skookum Chuck rivers and have a maximum
altitude of about 2,000 feet. Farther west lie the Black Hills,
whose highest altitude is probably not greater than 2,000 feet.

161

162 J. HARLEN BRETZ

These hills are bounded on the east and northwest sides by low,
wide valleys which constituted the two chief routes of glacial water
discharge from the basin of Puget Sound: The Olympic foothills
rise farther northwest in the main Olympic Range. At the time
of greatest extent of the ice, the northern slope of the Black Hills
was overridden and a lobe extended down on either side, the hills
determining a broad re-entrant in the ice front.

Il. PREVIOUS WORK ON THE MORAINE

In a general way, the glacial drift in Puget Sound has long
been known to terminate some distance south of Olympia, and
the gravel plains have been commonly recognized as outwash
deposits from the ice. No detailed work, however, has been done
in the region except by Willis and Smith on the Tacoma quad-
rangle.’ Here the contact between Pleistocene deposits from the
glaciers of the Cascades and Mt. Rainier and the Puget Sound
drift has been traced along the northwest flank of the volcano to
the southern edge of the quadrangle.

Warren Upham has described,? from a hasty reconnaissance,
what he believed to be the terminal moraine lying between the
base of Mt. Rainier and the Black Hills. He interpreted the
remarkable gravel mounds of the outwash plains of the region as
morainic topography of peculiar type.

No observer, so far as the writer is aware, has previously noted
the existence of the western lobe of the glacier, lying between the
Olympic Mountains and the Black Hills. .

III. MORAINE COURSE ACROSS THE GEOSYNCLINE

The westernmost geosyncline of North America is regarded
by stratigraphers as finding its representative on the Washington
coast in the Puget Sound depression. Were it not for the accident
of glaciation, this structural valley would today embrace a broad
inland sea, but the thick drift deposit constitutes a filling sufficient
to maintain most of the surface above sea-level. The terminal

t Bailey. Willis and G. O. Smith, ‘“‘Tacoma Folio, No. 54,” U.S. Geol. Survey.

2 Warren Upham, “Glacial and Modified Drift in Seattle, Tacoma and Olympia,”’
American Geologist, XXIV, No. 4.

TERMINAL MORAINE OF PUGET SOUND GLACIER 163

moraine is built far enough to the south to lie in general over rock
surfaces above sea-level; indeed, the moraine forms a fairly con-

MOUNTAINS

GLACIATION OF PUGET SOUND

Morrzontal Ruling ---- Extent of Vashon G/aciation
Ver(Gal fusing: — —= = On Fast = Cascade Weve and /¢e
On West —Olympic Neve and /ce
Dotled Areas =---—-—fytra-moraimc. Vashon Outwash
0 10 20 30

stant boundary between the depressed region to the north, now

drift filled, and the rugged, stream-carved rock hills southward.
The field work on which this paper is based has been done under

some difficulty because of the undeveloped nature of the country,

164 J. HARLEN BRETZ

and its incompleteness must largely be charged to the same reason.
Large tracts about Puget Sound are yet covered with virgin forest
whose density is such that passage for any considerable distance
is next to impossible. The lack of roads, trails, and inhabitants
over many square miles forces the investigator to shoulder his
pack of blankets and food, and travel the country on foot. De-
tailed work is not practicable under these circumstances. It will
probably be years before the moraine can be mapped with accuracy,
since the task must wait on the agricultural development of the
country.

On the eastern margin of the Tacoma quadrangle, Willis and
Smith? found a broad sheet of till spread by a piedmont glacier
from the Cascades. The contact between this drift sheet, named
the Osceola till, and the Vashon or youngest till sheet of the Puget
Sound glacier was found to be marked by a belt of hummocky
topography of morainic aspect, considerably different from that
of the ground moraine on either side. No definite marginal or
interlobate moraines were found, the phenomena being apparently
referable to subglacial accumulation. Short eskers were a notable
feature.

This study has taken up the continuation of the contact between
local glacial deposits, and those far traveled down the Puget
Sound depression from the north, on the south edge of the Tacoma
quadrangle in a densely wooded country traversed by a few second-
ary roads and one highway, the Mt. Rainier automobile road. The
geological map of the Tacoma folio maps the Rainier Pleistocene
drift on the south edge of the quadrangle, farther west than the
writer has found it. The automobile road follows a north to south
course for 5 or 6 miles, parallel to and about 6 miles west of Lake
Kapowsin, and for this whole distance traverses the till plain of the
Puget Sound Vashon glacier. Northward toward Tacoma are
extensive areas of outwash gravel deposited during the recession
of the Puget Sound ice. The till plain rises southward from the
outwash with an abrupt morainic slope, ascending 200 feet in one
mile. The slope is thrown into several successive ridges of till
trending east to west, on the south sides of some of which were

« Bailey Willis and G: O. Smith, of. cit.

TERMINAL MORAINE OF PUGET SOUND GLACIER 165

distinct kames. The till is the characteristic blue-gray arenaceous
material, with laminae and rounded cobbles, which is identified
throughout the Puget Sound country as Vashon. ‘The presence of
numerous varieties of rolled granite cobbles in the moraine and in
the plain southward is a safe criterion for the identification of the
till as the Vashon rather than the Osceola till of the Cascades.
The moraine ridges on its northern flank and broad till plain lying
southward are topographic features in accord with this interpreta-
tion. Though the boundary between Vashon and Osceola till
was not located, it obviously lies between the Mt. Rainier high-
way and Lake Kapowsin, the lake lying at the base of the foothills
of Mt. Rainier.

The dominance of Puget Sound ice at the western base of the
Rainier foothill country is proved conclusively by the common
occurrence of bowlders and cobbles of several granitic types char-
acteristic of the drift of Puget Sound and unknown to the adjacent
Cascades.

The postglacial gorge of Nisqually River, 300 feet in maximum
depth and with vertical and even overhanging walls, is two miles
~ long and occurs where the river enters the area of Puget Sound
drift. A 40-foot section of outwash, containing frequent Vashon
drift materials, overlies the rock floor in which the canyon is cut
at LeGrande. Farther up the canyon no drift was found.

A trail crosses the divide between the Nisqually and Des Chutes
rivers just south of the canyon noted, entering the latter stream
at the headwaters. Scattered granitic bowlders of Vashon drift
were found up to an altitude of 1,220 feet on the Nisqually side,
but no traces of drift were found in the remaining 200 feet of
ascent or in the valley of the Des Chutes on the other side until
the altitude of 1,200 feet was reached, a few miles down from the
headwaters. Here scattered erratics occur on the hillsides, and at
goo feet is a level terrace composed of fine material with inter- .
spersed pebbles, probably a lacustrine deposit caused by the ice
entering the lower valley and blocking the drainage.

Two miles below this terrace, whose soil has determined the loca-
tion of several small farms in the wilderness, is found the terminal
moraine of the Puget Sound Vashon glacier. The surface is exceed-

166 J. HARLEN BRETZ

ingly bowldery, granite is very abundant, kettles containing
lakelets and bogs are common, and the subsoil is typical Vashon
till. The margin of this bowldery drift may be traced about the
west and north of the Bald Hills from the Des Chutes to the
Nisqually River and is in places thrown into sharply defined ridges.
Occasionally the forest seems growing on one gigantic bowlder
heap. A preglacial valley descending to the northwest has been
dammed, giving rise to Little Bald Hill Lake, a picturesque body
of water in the heart of the wilderness. Another such valley has
three morainic ridges thrown across it at descending altitudes, a
marsh or alluvial flat lying behind each ridge. Pronounced relief
of the moraine on the north slope of the Bald Hills was found, but
the unbroken forest prevented satisfactory examination.

The same difficulty of examination is presented by most of the
country from the Bald Hills west to Tenino. In general, the drift-
covered area bears the farms and roads, the region immediately
beyond the ice limit rising in rocky hills which constitute the divide
between the Des Chutes River and the Skookum Chuck. A trav-
erse across this divide found the moraine disposed in bowldery
ridges along the base of the hills with a marginal drainage channel
separating the frontal ridge from the bold rock hill slope. No
erratic material or evidence of ice action was found on the ascent
to the divide crest, the glacier of Puget Sound having succeeded
in barely reaching the northern base of the hill region.

The town of Tenino is situated on an area of gravel outwash
lying immediately south of the moraine. The rock hills die away
toward the west just south of the town and glacial drainage escaped
southward to the lower Skookum Chuck through a broad, gravel-
filled valley. Glacial outwash was also carried westward from
Tenino toward Grand Mound and Gate to join the extensive
areas there outspread.

The Skookum Chuck bears a train of glacial gravel which entered
it somewhere in the unsurveyed region of the Huckleberry Moun-
tains, presumably from Mt. Rainier’s Pleistocene glaciers.- But
careful search revealed absolutely no granite or sedimentary meta-
morphics in this gravel for a distance of 6 miles along its course.
Only when the western limits of the rock hills were approached,

TERMINAL MORAINE OF PUGET SOUND GLACIER 1607

and below a low pass across the divide to the Des Chutes River,
was Puget Sound glacial gravel found in the Skookum Chuck
valley.

Clear Lake, at McIntosh station, 4 miles east of Tenino, lies
in a marginal drainage channel discharging westward into the
outwash gravel area at Tenino. The terminal moraine lies imme-
diately north of this lake. North of Tenino, the moraine is of a
character considerably changed from that in the Bald Hill region.
It has here become a single massive till ridge on the plain, and sur-
face bowlders are not sufficiently numerous to attract attention.
It is two miles wide and 250 feet above its base on both north and
south sides, the highest point examined reaching 550 feet A.T.
On each side, it is flanked by an outwash gravel plain bearing
peculiar tumuli. The till mass appears to cover several rock knobs
and hills, whose existence may have in some measure determined
its location and relief. Both east and west of Tenino, quarries
in sandstone have been opened on the slopes which rise farther to
the north in the moraine. ‘The road north from Tenino to Olympia
cuts into decayed shale strata im situ at the summit of its grade
across the moraine at about one-half the maximum height of the
moraine, and at McIntosh rock outcrops occur on the south base
of the moraine.

The hills which rise south of Tenino were carefully examined
for drift materials. Three distinct terraces of outwash gravel were
found, occasionally showing forests beds descending southward
toward the Skookum Chuck. The highest gravel lies 360 feet A.T.,
and above it drift abruptly ceases.

Flanking the frontal margin of the moraine from Tenino west
to Black River is an extensive area of outwash gravel, known as the
Grand Mound Prairie. It is entirely barren of forest growth
and almost useless for any agricultural purpose because of the
coarseness and depth of the gravel. At the contact between
moraine and outwash examined no apron structure was found.
The gravel plain apparently was built by outwash occurring through
breaks in the moraine ridge and not by outflow from the ice edge
when standing at its maximum limit. )

The whole region south of Puget Sound bears much outwash, both

168 J. HARLEN BRETZ

extra-morainic in position and lying back of the ice limit. These
areas are all alike in being natural prairies because of the coarseness
of the soil and in bearing a surface deposit of black silt of variable
thickness. Many of them exhibit a very interesting surficial
development into mounds of fairly uniform size and distribution
composed of mingled gravel and silt without stratification. Where
typically developed, they resemble a field of closely spaced hay-
cocks. Their origin is not clear. Grand Mound Prairie bears
these tumuli over a considerable portion of its extent.

Some distance back from the frontal edge of the terminal moraine
between Tenino and Little Rock a new railroad grade affords
frequent exposures of the Vashon till overlying drift of much
greater age and with bedrock often appearing beneath the drift.
Hills of the moraine occur on the east side of Black River a mile
south of Little Rock, while across the river on the west, a morainic
tract of low relief occurs about a mile wide. In this tract is a
splendid exposure of Vashon till highly charged with rounded
gravel which is doubtless overridden and incorporated outwash
material.

Mima Prairie, southwest of Little Rock, is another part of the
outwash gravel plain and forms a sharp re-entrant angle in the
surface till exposures, though hardly recording such an ice margin
form, the till being probably buried beneath this northward angle
of the outwash. Between Mima Prairie and the Black Hills,
unweathered Vashon till was observed in a gravel pit with a thick-
ness of three feet overlying a very red and decayed till of undeter-
mined depth. Small pebbles of the latter were often easily cut
in two with a knife, while those of the overlying Vashon were firm
and unweathered.

No drift is found back in the Black Hills except a sprinkling of
pebbles in re-arranged residual material on the slopes which face
the broad drift plain eastward. The region is exceedingly difficult
to examine, the forest being almost impassable. Entrance into
the hill region is gained on a logging railroad and on various trails.
One road crosses near the northern part of the hills, passing west
from Olympia close to Summit Lake. Drift has been found near
this lake on the north slope of the hills up to an altitude of 1,460

TERMINAL MORAINE OF PUGET SOUND GLACIER 169

feet, falling short a few tens of feet of reaching the summit. No
till has been found in the valleys of any of the south-flowing streams
of the region. f

Summit Lake lies in the upper part of a preglacial valley, the
lower southern portion of which bears a drift filling. The ice
sheet certainly overrode the divide at the northeast of Summit
‘Lake but it brought over no drift. Farther south, however, the
valley opens into a larger one trending east and west, and from
both directions in this, till was carried into the Black Hills. Again
the relation of agriculture to the drift is illustrated in the occurrence
of several small farms on the broadened valley floor produced by
drift filling while elsewhere the region is covered with primeval
forest or the waste of logged-off land.

At least two distinct valley trains cross the western part of the
Black Hills to the Chehalis River, the larger of these being a filling
so complete that several rock hills rise like nunataks from the
gravel plain. This enters the Chehalis valley at Elma, in the
vicinity of which it is deeply incised by creeks, its structure being
thus plainly revealed. A feature of the gravel is the prevailing
reddish color, fairly uniform throughout the mass. The freshness
of the pebbles and the youthfulness of drainage on the plain,
however, show this staining to be due to some other cause than
age. The Vashon till near the head of this valley train is also
deeply red while its pebbles are fresh. The explanation is thought
to be found in the incorporation of residual material from the
basalt rocks of the Black Hills.

The country lying between these hills and the Olympic Moun-
tains is practically a great gravelly waste. The forest is thin over
large areas and open prairies occur in the region south of Hood’s
Canal. The moraine hills when found are often largely buried in
outwash and the extreme limit of the ice as mapped is consequently
only approximate, being based on the occurrence of till outcrops
above the gravel plain. No definite ridging tangential to the ice
margin was observed in the till hills seen, though their occurrence
forms a zone a few miles wide, whose outer margin has been indi-
cated as the limit of Puget Sound ice to the west.

The character of the till, where exposed in railroad cuts and

170 J. HARLEN BREDZ

stream valleys, appears identical with that shown in the vicinity of
Seattle, on the slope of the Bald Hills, and in other widely separated
regions. The matrix is somewhat sandy, the pebbles and bowlders
are rounded, and large erratics are rare. Granite of various kinds
is abundant, though granite is not known in the neighboring
Olympics. The till is seen to overlie fresh gravel in a few sections
with a thickness of about three feet. Its altitude probably does —
not reach much above 450 feet A.T.

Lake Nahwatzel lies in a decidedly morainic area, the monoto-
nous gravel plain giving place to rolling hills of till which rise 50
feet above the lake surface. These morainic hills lie probably
over the lowest preglacial rock surface between the Black Hills
uplift and the Olympic foothills, and in such a situation we may
find an explanation of the more pronounced morainic expression.

The till along the margin from Matlock to the Black Hills
often shows a large proportion of deep red clayey material inter-
mingled with fresh pebbles. The presence of such material,
doubtless from the incorporation of the residual soil of basalt of
which there are frequent outcrops, is to be expected near the ice
margin providing the ice was overriding a region previously
unglaciated.

The approximate moraine course from Matlock northward
bends abruptly back toward Hood’s Canal, the greater length of
which is closely bordered by the Olympic Mountains on the west.
The extent to which Puget Sound drift penetrated into the valleys
of these mountains is known in but one case, that of the Skokomish
River. Rock along this stream’s course is practically absent below
Lake Cushman, while the mountain walls rise almost from the lake
shores on the upstream side.

Puget Sound drift of Vashon age composes an extensive plateau
400-800 feet above Hood’s Canal, extending back from Lilliwaup
Creek directly west to Lake Cushman and also southward to the
broad, pre-Vashon lower Skokomish valley. One large rock hill
rises through this till plateau just south of the Lilliwaup, otherwise
the surface is of rolling ground moraine with occasional shallow
kettles. Across the Skokomish to the west are foothills with little
orno drift. To the south of the great bend of this stream, extensive

TERMINAL MORAINE OF PUGET SOUND GLACIER 171

outwash gravels begin, continuing to Shelton in one direction and
across the Puget Sound divide to the Satsop in another. In this
latter direction, the outwash largely buries the moraine near Mat-
lock and becomes extra-morainic in its further extent.

On the east side of Lake Cushman, the till plateau becomes
ridged and kettley, though a dense forest prevents satisfactory
examination. The morainic character is best seen along the trail
from the head of the lake to Lilliwaup. The material on the lake-
ward face of these ridged drift hills nowhere contains granite, though
two very careful examinations were made. In but one place are
granite pebbles found on the shore or in the immediate vicinity
of the lake, this being in the bed and delta of the largest stream
entering the lake from the northeast. Yet a mile back from the
lake, to the east, granite bowlders are found lying on the surface,
becoming very numerous two or three miles farther east.

The limit of the Puget Sound drift is thus seen to lie close to
the lower end of Lake Cushman, the basin of which is caused by
the damming of the Skokomish River valley. The inner slope of
the drift dam is probably faced with the terminal deposits of the
Skokomish valley glacier, which was unable to advance farther
in the face of the overwhelming mass of the Vashon glacier. It
may have earlier deployed farther out on the plain, but if so the
deposits are buried beneath the Vashon drift. That a valley
glacier must have existed back of the drift dam of Lake Cushman
when the Puget Sound ice was at its maximum is evident, else the
lake basin would have filled with outwash. A till with very
angular débris, none characteristic of Puget Sound drift, lies back
of the drift dam on the slope of Mt. Ellinor, immediately north of
the lake. It is estimated to reach 500 feet higher than the lake
surface.

As shown on the map, the western margin of the Puget Sound
glacier north of Lake Cushman is approximate only. .The moun-
tains rise close to Hood’s Canal throughout the remaining distance
included in the accompanying map, and in all probability there
existed no embayment of Puget Sound ice in the other river
valleys entering the Canal comparable to that of the Skokomish
valley.

172 J. HARLEN BRETZ

IV. GENERAL CONSIDERATIONS

Considering the altitudes of the terminal moraine only where
facing driftless country to the south, its crest is found to have no
great range in elevation above the sea. On the north slope of the
Bald Hills, near the headwaters of the Des Chutes River, the
moraine crest 1s probably nowhere more than goo feet A.T., though
erratics occur 320 feet higher. Near Tenino, where the moraine
is most typically developed on the plain, the crest is probably less
than 600 feet in altitude. The existence of buried rock hills in
the moraine in this region has been noted. At Little Rock, the
moraine surface on the west side of Black River can hardly have
been lowered by erosion of escaping glacial water or subsequent
stream action, and is approximately 150 feet above the sea, the
lowest altitude in the moraine. From this altitude is a descending
slope southward, on which the ice ceased to advance. The oppos-
ing northern flanks of the Black Hills, deeply cut by valleys, did
not permit assumption of the moraine form. Drift, however, has
its upper limit in the re-entrant angle which they produced, at
an altitude of 1,460 feet. The flattened lobe northwest of these
hills has its moraine hills about Lake Nahwatzel at 450 feet A.T.
Puget Sound and Olympic drift damming Lake Cushman reaches
observed heights of 950 feet above the sea.

The data available for an estimate of the thickness of the ice
and its frontal slope are meager. Three miles from Little Rock,
the glacier left its till at the eastern foot of the Black Hills at an
altitude of about 150 feet. From here it is 10 miles north’to the
upper drift limit near Summit Lake, at 1,460 feet A.T. The slope
in this instance is approximately 130 feet per mile. Fifteen miles
east of Seattle rises the peak of Mt. Issaquah, about 3,000 feet A.T.,
whose frost-riven summit bears no residual soil comparable to
that found on hills of much the same lava rock beyond the limit
of the drift: Scattered erratic pebbles were found on the summit,
their number increasing on the lower slopes. With the maximum
depth of the Sound near Seattle at 964 feet, we may conclude that
in the latitude of Seattle the glacier attained a thickness of 4,000
feet, allowing very little for central surface convexity, which would
increase the estimate an unknown amount.

TERMINAL MORAINE OF PUGET SOUND GLACIER 7.8

Evidence of the lack of vigorous movement near the frontal
margin of the glacier is shown in the occurrence of deeply decayed
material overridden by the ice. Shale strata, profoundly decom-
posed, are exposed east of Little Rock. Though slightly crumpled
and in one case bearing an intruded arm of the till, this incoherent
and rotted shale has been but little eroded by the ice, though it
is two or three miles back from the moraine front. West of Little
Rock, where Vashon till is found at its farthest southern extent
along the Black Hills, a knob of old red till is exposed beneath it.
Depth of weathering and staining are the same on the slopes as
on the summit of this knob, hence the inference that no erosion
of the projecting softened till was produced by Vashon ice.

The accompanying map indicates only the extra-morainic out-
wash. Great areas lie within the moraine limits of essentially the
same character and age. In the case of all outwash deposits, the
discharging water was received by the Chehalis valley largely
on the east or west side of the Black Hills. Extensive tracts are
rendered as worthless for agriculture by these outwash plains as
though in an arid country. For example, the road through the
sparse forest extending from Lake Nahwatzel to Shelton crosses but
one stream bed and this carries water only during the very rainy
winters and no valley has been cut. As already noted, the moraine
across the low area between the Black Hills and the Olympic foot-
hills has been partially buried in the flood of gravel and its relief
much reduced.

The question of contribution from valley glaciers in the border-
ing Cascades and Olympics cannot be adequately treated in our
present state of knowledge. Valley glaciers in these mountains
on the Soundward slopes debouched into a great mass practically
filling the depression from rim to rim. That they would perform
much erosion under such conditions is not to be expected. Willis
has found the till sheet of a Cascade piedmont glacier on the eastern
part of the Tacoma quadrangle, a part of which is indicated on
the accompanying map. The relative insignificance of the Skoko-
mish glacier whose lower extremity occupied the basin of Lake
Cushman has been shown. No evidence has yet been found that
tributary glaciers north of these two produced any perceptible

174 J. HARLEN BRETZ

effect on the mass of the course of the great Vashon glacier, whose
volume and thickness was of course greater northward.

Definite recessional moraines are yet unknown in the Puget
Soun~ cocntry. Between the terminal moraine and the southern
arms of the Sound are occasional moraine hills and ridges which
will probably resolve themselves into linear arrangement when
carefully studied and will constitute recessional moraine deposits.
But in the larger area of longitudinally ridged drift among the arms
of the Sound, there is little of morainic origin beyond scattered
lodge moraine hillocks in the valleys.

Russell’ first noted that there are two till sheets in Fuget Sound
basin, recording two glaciations. Willis? has named these the
Admiralty and Vashon, with the latter of which we have had to do.
The frequently weathered condition of the Admiralty till or of its
superposed outwash has been pointed out by Willis as evidence
of long exposure before the Vashon glaciation. The freshness and
slight erosion of the Vashon till sheet and moraine evince an age
comparable to that of the Wisconsin drift.

A notable feature of the Puget Sound glaciation, shown by the
failure of constant careful search to find older till beyond the
moraine, is that the last glaciation of the region, doubtless Wiscon-
sin in age, was the most extensive. Frequent incorporation of
residual soil in the Vashon till is the best evidence which might
be secured, in the absence of deep sections, that it overlies areas
never previously glaciated.

' Bailey Willis, ‘‘ Drift Phenomena of Puget Sound,” Bull. Geol. Soc. Am., IX.
2 Willis and Smith, ‘“‘Tacoma Folio No. 54,” U.S. Geol. Survey.

2) DIRO RIAL

THE SEEDING OF WORLDS

As a sort of initiation stunt precedent to admission into the
fraternity of agencies of good and regular standing, every new
agent that is brought into view by the ongoings of science is likely
to be set to the task of solving some large part of the outstanding
puzzles that still vex the wise men of our craft. “Light pressure”’
is one of the latest novitiates on trial, and has been set to the
stunt of seeding the habitable but not inhabited worlds by spores
from some previous spore-growing world. The seeding of the first
world is mercifully not made a part of the stunt. So too, to help
out the novitiate somewhat, the hazards of the cold of space are
mitigated by bringing to bear certain novel tenets about endurance
of extreme cold, and by cutting the time by the great speed of the
trip from world to world under the new pressure. ‘The stunt still
remains a stiff one and is interesting, but the fraternity seems to
be missing the best part, the getting home to the new world; no
doubt because it is so far off.

The start of the spore from the spore-growing planet is not
without its little difficulties; for the seed, be it even so light as
the airy fluff of the puffball, must yet not only get out to the very
top of the air, but it must be pushed off by the pressure of the light
at a speed of some 5 or 6 miles a second to be able to get away
from the pull of the parent world, if that world be a body like our
familiar acquaintance, the earth. A Krakatoan blast, however,
can no doubt give the spore a lift, if need be. But the getting away
is not the interesting part of the stunt; it is the landing.

If ‘“‘light pressure’? has once pushed the spore out of the clutches
of the parent world and got it well under way, all is likely to go
well till the bounds of the sun’s sphere of control are reached and
the border of the domain of the other sun is entered, for that sun
is likely to push back as much as the parent sun pushed out. In
matters of this sort one sun seems unwilling to be the dumping-

aed

175

176 EDITORIAL

ground of another sun. So now, between the opposing pushes
of the rival suns, comes the real trial of skill or luck in landing the
spore. If the seed be duly planted, the fraternity door should
surely open for the candidate magna cum laude.

On leaving the domain of the old sun and entering the field of
new suns, care or luck in hitting on a sun that shines less bright than
the one that has pushed the spore out is surely needed, or else the
back-push of the brighter sun will grow in time to be stronger
than the on-push of the old sun and the spore will be stopped or
turned aside. If someone churlishly remarks that the seeding
of new worlds can thus only go down the scale of solar radiance,
let that pass; it is enough to seed at long distance any world.

Hitting upon a sun of duly lesser radiance, the spore must
shoot straight for it, quite straight, center to center, for if the
backward push of the sun ahead is a little awry at the front, the
spore will be pushed aside and out of line, and once off the line it
will be turned more and more away and surely go astray. Nor
must the chosen sun move out of line while the spore is coming
toward it, or else the front push will surely turn the spore away.
No sun must be hit upon but one that will stand still, if such there
be, while the spore is getting home to the new planet, or, if no sun
stands still, a sun must be hit upon that is coming toward or else
is going straight away from the advancing seed.

All ill luck in hitting the right path or in hitting on a sun moy-
ing straight toward or straight away from the speeding spore once
duly escaped, the larger perils are past, but not all; there are
perils of side pushes. In hitting upon a star of proper weakness
of radiance and coming or going or standing still duly, the spore
may chance to pass some brighter star off the line and its side push
may turn the spore off its course; or stars may be thicker or brighter
on one side or another and the spore be put off its course by their
united pushes. Where, then, it may ayain be churlishly asked,
is a spore to go if all the suns push it away? Well, it is not a part
of this stunt to chase up lost spores; still, there are ‘“‘dark lanes”
and ‘“‘coal sacs”? and ‘‘openings”’ leading out into room “outside
the universe.”

Then too there are perils of planets as well as perils of suns.

EDITORIAL 177

As the spore pushes down against the radiance of the defendant
sun, one of whose planets, near enough to it to keep duly warm,
is to be seeded for a new life kingdom, a planet just at the right
spot must be hit upon. Luck must here stand the spore in good
stead, for the chances are not the best. If the planets of the chosen
sun circle round it cross-ways, in any but the minutest degree,
they will never be in the center-to-center line of the spore’s path,
for, as we have seen, the spore must keep true to line or the back-
ward push of the light pressure in front, striking aslant, will turn
the spore off. There is a chance indeed that a spore will get down
to just the right point and then be turned off just so as to strike
a planet that is off line, but it is not a chance to stake much on.
To have any fair chance of getting home to a planet while the spore
keeps straight on toward the repellent sun, under the superior
inertia it got from the sun it left, the planet must circle round the
sun in a path that cuts this line.

And then, too, the planet must be there at just the right time.
The spore must no doubt cross the spot in the wink of an eye, or
less, and the new world must be there on exact time if it is to be
seeded. It is not unfair that it should be made to be there on
time as its part of the stunt, for the spore has come far to do its
part. .

Now if all has gone well thus far there is only the landing left.
Ii the spore was pushed out from the old sun too fast, it may plunge
so swiftly into the air of the new world as to strike fire and burn
or brown itself fatally. But if pushed out just right at the start
and pushed back just right on the road, it may land with little
more than the speed forced by the pull of the new earth, a matter
of a few miles a second, it may be.

When the speed of the spore is stopped and it floats in the
outer air of the new earth it may perchance from being too hot
come quickly to be too cold and the change from warmth to chill
may try its salamandrine powers before it sinks to the warm air
low down or to the ground in which it is to grow.

The luck of the spore must stay by it a little farther in its
lighting. All may be lost if it falls on polar snow, or mountain
peak, or desert plain, or perchance in the ocean midst, if it is not

178 EDITORIAL

a salt-water spore. It must fall in a spot where it can grow, where
its family, as it comes to have one, may live and multiply and grow
into a kingdom, for if it fails in this last, the kingdom will not
be won.

The stunt may be perilous; but it is easy to see how easy it
is to do if done just right. Light is the great foster-farmer of the
earth, the truly great farmer; and we now see how clearly and
truly ‘‘light pressure” is the long-distance seed-planter of the
worlds. Te Cace

ARTESIAN WATERS OF ARGENTINA

The climate of a part of Argentina is semi-arid, and the geo-
logical formations which are regarded as Quaternary and Later
Tertiary are, in the western and central districts of the country,
saline to a degree which indicates prolonged duration of aridity.
The region of the Pampas which covers the province of Buenos
Aires and stretches northward west of the Parana does not exhibit
this characteristic, having apparently long enjoyed a more humid
climate, as it does now. The foothills of the Andes are also well
watered. But with the exception of these last-named regions, a
great part of the country suffers from lack of good water. This
condition may, however, be in some measure relieved by proper
development of artesian supplies. Many wells have been sunk
already, but without adequate geological investigation. In the
Pampas, water is found at a general depth of 20 meters more or
less, and is pumped to the surface by windmills. It may be said
that the development of the livestock industry of Argentina would
be impossible were it not for this supply which comes from eolian,
alluvial deposits of Quaternary and Tertiary age. A different
geological condition exists from the Rio Colorado southward in
what may be best described as northern Patagonia. In that
region there are local elevations occupying a middle position
between the Atlantic and Pacific, composed of granites and older
rocks possibly of Paleozoic age, and rising to altitudes of 300 to
1,000 meters. These mountains are not represented upon any
map and their distribution is not known, but they have been de-
scribed by Moreno and other explorers. Upon their flanks there

EDITORIAL 179

is an extensive formation of gray sandstone which attains a thick-
ness of several hundred feet and is very porous. It slopes gently
toward the Atlantic and pure water flows from it in outcrops near
the coast. The head of water in these strata is unknown. Farther
south in Patagonia the central sierra is replaced by plateau country
and in Comodoro Rivadavia, in latitude 46 near the coast, wells
which were sunk by the government in search of water developed
petroleum. There is a large area in this region in which the
geologic structure and the possibilities of artesian water need to be
developed. In the great plains east of the Andes there are glacial
deposits which may furnish superficial supplies like those of the
Dakotas, and the marine Tertiary and Mesozoic strata afford con-
ditions not unlike those of southern California. Here as well as
in the valleys among the spurs of the Andes from Patagonia to
Bolivia the geological structure is complicated and the problem
of artesian water is one of peculiar difficulty as well as of great
interest.

Our present knowledge of these conditions rests upon recon-
naissance work and the stratigraphic and paleontologic observa-
tions of the Geological Survey of Argentina. No work based
upon topographic maps and systematic structure has as yet been
undertaken. The problem is therefore one whose elements are as
yet to be developed. The Argentine government is using every
means to encourage settlement and development of the rich agri-
cultural regions which lie in the zone of sufficient rainfall east of the
Andes, and also the vast grazing district of Patagonia.. In order
to afford ready communication it is building railroads at great
national expense and operating them. Zhe need of pure water
for locomotive use as well as for other purposes has thus been made
critically evident, and the minister of public works, Senor Ramos
Mexia, has adopted a plan for making surveys for the determina-
tion of artesian water conditions along the lines of national rail-
ways. He contemplates topographical and geological surveys of a
character similar to those executed by the United States Geological
Survey, from which he derived the initial suggestion. He last
summer applied to the United States government for the services
of a geologist and such assistants as he might need, and our govern-

180 EDITORIAL

ment has responded cordially to that request. Mr. Bailey Willis
has accordingly entered into a contract for the term of two years,
to execute topographical and geological surveys for the specific
purpose of ascertaining artesian water possibilities in those districts
which the minister may designate. With him are associated Mr.
Chester W. Washburne of the United States Survey, Mr. J. R.
Pemberton of Stanford University, and Mr. Wellington D. Jones
of the University of Chicago, as geologists, and Mr. C. L. Nelson
and Mr. W. B. Lewis as topographers, and the party has recently
sailed for Argentina to enter upon the work. While these surveys
have a specific purpose, their possibilities of usefulness in develop-
ing the natural resources and encouraging settlement in the regions
surveyed will not be overlooked, and the work will be founded on
those scientific studies upon which alone practical conclusions
can safely rest. Thus it is hoped that a definite contribution to
knowledge in geography and geology may be made.

It is desirable to point out that the Argentine government has
a geological survey which has been in existence since 1903 in its
present organization and which dates back half a century as a
bureau of mines. It is under the direction of Senor E. M. Her-
mitte, who is assisted by Messrs. Bodenbender, Keidel, and Schil-
ler, three German geologists who have done excellent stratigraphic
and paleontologic work, particularly in districts of the central
‘Argentine Andes. They have unfortunately not been supplied
with maps. The established Bureau of Mines, Geology, and
Hydrology is under the Minister of Agriculture. The surveys
which are about to be made are undertaken by the Minister of
Public Works. The two operations are thus officially distinct,
but it is hoped and anticipated that they may be mutually helpful.

B. W.

PETROGRAPHICAL ABSTRACTS AND REVIEWS
Epitrep By ALBERT JOHANNSEN!

BENEDICKS, CARL, AND TENOW, OtoF. ‘“‘A Simple Method for
Photographing Large Preparations in Polarized Light,” Bull.
Geol. Inst. Univ. Upsala, 1X (1910), 21-23.

For the description of the comparatively simple apparatus used,

reference must be made to the original paper.
W. T. SCHALLER

Bow tes, OLiver. Tables for the Determination of Common Rocks.
New York: Van Nostrand, 1910. 16mo, pp. 64+84 advs.
50 cents net.

Cui bono ?

Written, as this book is, for “‘beginners in lithology,” it is especially
unfortunate that the author’s statements are often very misleading.
For example, in the chapter on “Rock Classification”? the statement is
made that “igneous rocks ... . represent the original solid crust of
the earth,” and that “sediments . . . . are but modifications, or recon-
structed phases, of this primary type.’ A short chapter on the deter-
mination of the rock-forming minerals is followed by 18 pages of tables
for the determination of the common rocks. The methods of identifica-
tion are given in extremely brief form, but would a “beginner,” or any-
one else, classify andesite, quartz porphyry, felsite, or phonolite as “ashy,
and often with a few phenocrysts, mostly cellular”’ ?

The book ends with a ten-page chapter on “ Building Stones” and a
seven-page glossary. The volume is No. 125 of Van Nostrand’s Science
Series and is uniform in size and binding with the remainder of the set.

ALBERT JOHANNSEN

Bowman, H. L., anpD CLarkE, H. E. ‘On the Structure and
Composition of the Chandakapur Meteoric Stone,” Min. Mag.,

XV (1910), 350-76. Pls. 2, and analyses.
A full description, with extensive chemical work, ona large piece of
the meteoric stone which fell at or near Chandakapur, India, on June 6,
t Authors’ abstracts will be welcomed and may be sent to Albert Johannsen,

Walker Geological Museum, The University of Chicago, Chicago, IIl.
181

182 PETROGRAPHICAL ABSTRACTS AND REVIEWS

1838. It is an intermediate chondrite, with olivine and pyroxene as the
most important constituents. Metallic iron and nickel form nearly 6
per cent, and combined iron and nickel, 5 per cent.

W. T. SCHALLER

Date, T. Netson. ‘‘The Cambrian Conglomerate of Ripton in.
Vermont,” Am. Jour. Sct., XXX (1910), 267-70. Figs. 3.

A conglomerate formed of pre-Cambrian pebbles generally held
together in a highly metamorphosed “muscovite-quartz schist with
more or less magnetite.” The pebbles are a beach formation and are of
local origin as is shown by their large size and by their similarity to

adjacent rocks.
ALBERT JOHANNSEN

Duparc, WUNDER, AND Sapot. ‘“‘Les minéraux des pegmatites
des environs d’Antsirabé 4 Madagascar,” Mém. Soc. Phys.
et d’Hist. Nat. Genéve, XXXVI (1910), fasc. 3, 283-410.

The geology of Madagascar is briefly described and then, in detail,
are described the rocks around Antsirabé. These include basalts,
granites, quartz diorites, pegmatites, cipolines, quartzites, and mica
schists. The localities of the pegmatites are then given in detail. The
pegmatites occur chiefly in the cipoline and are formed principally of
microcline and quartz, or plagioclase (near albite) and quartz. Mica,
tourmaline, beryl, garnet, and pyroxene are also present.

In the second part of the paper are mineralogical descriptions of
microcline, amazonite, lepidolite, lithionite (zinnwaldite), beryl (rose-
pink and aquamarine), tourmaline, spodumene, spessartite, garnet, and

cordierite from the mica schist of Mount Ibity.
W. T. SCHALLER

GraBHam, G. W. ‘An Improved Form of Petrological Micro-
scope; with Some General Notes on the Illumination of Micro-
scopic Objects,” Min. Mag., XV (1910), 335-49. Figs. 5;
Dit

Suggests several improvements on a Dick microscope, namely, a
better adjustment for the condenser system, a triple nose-piece, iris
diaphragm, and a slot for introducing screens below the stage. The
graduated circle is placed below the ocular. Several other suggested
improvements have already been used on other microscopes. Several

PETROGRAPHICAL ABSTRACTS AND REVIEWS 183

pages are devoted to the “Illumination of the Object.” An explanation
of the ‘“‘white-line effect”’ (Becke’s line) is given for parallel light where
the contact plane of the two minerals tn question is at various inclinations.

W. T. SCHALLER

GRAYSON, H. J. “Modern Improvements in Rock Section Cutting
“Apparatus,” Proc. Roy. Soc. Victoria, XXIII (1910), 65-8t.
Risin:

Describes an apparatus, constructed for the University of Melbourne,
with which the writer is able to slice, grind, and mount thin sections of
about an inch in diameter and of a thickness of less than 0.001 inch,
from rocks of the hardness of granite, in not more than ten minutes.
Using two cuts with a diamond saw for each slide, the cost per section
is about one shilling.

A mechanical device for doing the rough grinding would be an im-
provement. With a number of laps running simultaneously, the greater
length of time required for each section would be no drawback, and there
would be a considerable reduction in cost since it would not be necessary
to use diamond dust.

ALBERT JOHANNSEN

Grout, FRANK F. ‘“‘The Composition of Some Minnesota Rocks
and Minerals,”’ Science, XXXII (1910), 312-15.

A preliminary statement regarding the composition of certain Minne-
sota rocks. There are given analyses of seven rocks and fourteen
minerals.

Two or three types of granite occur in laccoliths of considerable size
in the Keewatin schists and are considered by the author as probably of
that age. These granites are intersected by diabase, quartz diabase,
and quartz porphyry dikes, and there occur a few masses of gabbro.
Most of the Minnesota effusive rocks belong to three types of diabase
which, chemically, are classed as Hessose, Bandose, and Auvergnose.

The country rock was tested for copper. The common theory of
the origin of the Lake Superior copper deposits is that of lateral secretion
from the diabases. In the present tests it was found that copper occurs
in all the main types of rock, and, so far as could be judged from the ten
samples tested, the fresher the rock, the larger the amount of copper.
It varied in amount from 0.029 to o.o12 per cent.

ALBERT JOHANNSEN

184 PETROGRAPHICAL ABSTRACTS AND REVIEWS

Hoécsom, A. G. ‘‘Ueber einen Eisenmeteorit von Muonionalusta
im nérdlichsten Schweden,” Bull. Geol. Inst. Univ. Upsala,

TX (i010) 220538) elem
This is a description of the first iron meteorite found in Sweden. The
essential constituents are the iron-nickel kamazite, taenite, and plessite.
Troilite and daubréelite form a minor part. Chemically, the meteorite

contains or per cent Fe and 8 per cent Ni.
W. T. SCHALLER

Dre LapPpARENT, JACQuES. ‘“‘Les gabbros et diorites de Saint-
Quay-Portrieux et leur liaison avec les pegmatites qui les
traversent,”’ Bull. de la Soc. Francaise de Minéralogie, XX XIII
Goro), 254-70:

Near Saint-Quay-Portrieux on the coast of Brittany, intrusive in
mica schists, there is a mass of rather coarse hypersthene-gabbro with a
periphery of dioritic facies. Both gabbro and diorite contain inclusions
of a finer-grained hypersthene-bearing rock with the structure of beer-
bachite. These rocks are cut by dikes of aplite essentially composed
of labradorite and quartz. The diorite and the marginal, but not the
central, part of the gabbro are cut also by small dikes of pegmatite com-
posed essentially of microcline, albite, quartz, and a little biotite, with
local muscovite and tourmaline. The albite has crystallized before the
microcline.

The principal types are represented by five analyses.

The microscope shows the hypersthene of the gabbro in process of
replacement by a mixture of biotite and quartz, and the augite more
or less uralitized. In the peripheral “‘diorite’”’ both alterations are much
more advanced; the augite is almost completely uralitized, and the
hypersthene wholly replaced by biotite and quartz. The author ascribes
these changes to the agency of the pegmatite and believes them to have
been effected before the gabbro was fully consolidated. He considers
for reasons not fully stated that the first phase was the production of
soda-lime feldspar by the reaction with the femic magma of siliceous
alkaline vapors, rich at first in soda. He supposes the vapors subse-
quently to have become more abundant and richer in potash, water, and
boric acid. The quartz and biotite, it is pointed out, would be formed
by combination of the constituents of hypersthene with those of potash-
feldspar; there is evidence that this reaction took place in the central
gabbro before the hypersthene was completely crystallized, and in the

PETROGRAPHICAL ABSTRACTS AND REVIEWS 185

peripheral “diorite”’ even before that mineral was individualized. The
transformation of augite to amphibole, accompanied by crystallization
of quartz, is considered to have been the final reaction, effected mainly
by the water and boric acid in which the vapors became relatively richer
as the consolidation of alkalies and silica progressed.

M. de Lapparent believes that the action of the kind here described
is common, and especially, that it has occurred in certain American rocks.

F. C. CALKINS

MicHEL-LEvy, ALBERT. ‘“‘Les terrains primaires du Morvan et
de la Loire,” chap. v, ‘‘ Etude pétrographique et chimique des
roches éruptives du faisceau synclinal du Morvan,” Bulletin
des Services de la Carte Géologique de la France, XVIII (1908),
209-68.

The area described is part of the central plateau of France, made
classic by the thorough studies of the elder Michel-Lévy and others.
Its rocks furnished the basis for some important principles of the science,
and some of them are illustrated in the beautiful plates that accompany
the ‘‘ Minéralogie Micrographique.” <A historical summary and bibliog-
raphy relating to these early researches is given in the present work.
The petrographic descriptions in this work are brief; its principal con-
tribution is a series of chemical analyses, twenty-five in number, which
are used to show the position of each rock in the American quantitative
classification and in that of Michel-Lévy.

The principal deep-seated rock is a coarsely porphyritic granite
(alaskose) with potash distinctly more abundant than soda. The pheno-
crysts of potash feldspar are the last constituents to crystallize. This
rock passes into microgranite and ‘“‘microgranulite.”’ Associated diorite
(hessose) and amphibolitic porphyries (andose and tonalose) are said
to have been formed by digestion of calcareous sediments in the granite.
No full argument in support of this assertion is made, the author evi-
dently considering that previous work by Michel-Lévy and Lacroix
has established the frequent occurrence of this: type of endomorphism.

The exomorphic action of the granite has affected limestones, shales,
sandstones, and conglomerates. The most interesting result of the meta-
morphism has been the introduction of albite and orthoclase in all these
rocks, especially in close proximity to contacts, by “alkaline fumaroles”
from the magma.

The volcanic rocks—of Paleozoic age—comprise: (1) Upper Devo-

186 PETROGRAPHICAL ABSTRACTS AND REVIEWS

nian albitophyres, in the form of breccia and tuffs, with phenocrysts of
albite, orthoclase, microperthite, and rarely of brown hornblende, in a
groundmass of albite microlites. In the quantitative system these
belong to dacose, andose, and subrang 5 of dacose, not named nor even
represented by analyses when that system was published. (2) Carbon-
iferous orthophyres, also in the form of tuffs and breccias. The pheno-
crysts are of orthoclase, albite, and in some cases anorthoclase; the
groundmasses where crystalline are of orthoclase microlites and poikilitic
quartz; some are glassy and perlitic. They belong to alaskose, liparose,
and the unnamed subrang I (perpotassic) of alaskose. (3) ‘‘Micro-
granulitic tufts,” consisting of fragments of andesine, bipyramidal quartz,
and biotite in a chalcedonic cement. These are water laid and appar-
ently not of purely volcanic material. They belong to toscanose and
are more limy than the albitophyres. (4) ‘‘Microgranulites.” Some
of the rocks thus designated are hypabyssal, others, passing into “por-
phyre pétrosilicieux,” are thick, devitrified rhyolitic flows. An analysis
of the hypabyssal rock is that of a toscanose, while the two specimens
analyzed of the extrusive rock are alaskose and liparose. (5) Lampro-
phyres. These also occur partly as thin dikes and partly as flows.
The dike rocks have phenocrysts of biotite and pyroxene in a ground-
mass of orthoclase, plagioclase, and biotite; the lavas have phenocrysts
of olivine, augite, and sometimes hypersthene, in a groundmass of
plagioclase, orthoclase, and sometimes biotite. In the quantitative
classification, they are harzose, shoshonose, and auruncose. Chemically
both extrusive and intrusive ‘“‘lamprophyres” are characterized by
richness in potash, resembling in this respect the porphyritic granite
from which they are supposed to be differentiates.

The author summarizes the chemical data by estimating the average
composition of each group of rocks and of all the rocks together excepting
the diorites, albitophyres, and granulites. With these exceptions, all
are markedly consanguineous, and the general average composition has
in the scheme of Michel-Lévy the same “magmatic parameters”’ as the
granite supposed to be the ‘“‘mother-rock.”’

The albitophyres, by their richness in soda, are in remarkable con-
trast to the other rocks, in which dominance of potash is general. It is
a striking circumstance that names are wanting in our quantitative
classification for two of the albitophyres because of their unusual richness
in soda, and for two other rocks—an orthophyre and a lamprophyre—
because of their unusual richness in potash.

F. C. CALKINS

PETROGRAPHICAL ABSTRACTS AND REVIEWS 187

NORDENSKJOLD, Ivar. “‘Der Pegmatit von Ytterby,” Bull.
Geol. Inst. Univ. Upsala, TX (1910), 183-228.

Numerous lenses of pegmatite occur at Ytterby on Resaro Island,
about 20 km. E.N.E. of Stockholm. Some of the pegmatites are found
between diorite and gneiss, and others occur in hornblende gneiss. A
zonal structure is noticeable, the pegmatites being finest grained near
the contact. Large masses of pure red potash feldspar (microcline
perthite), white plagioclase (oligoclase), and massive quartz are found
in the center of the lenses. The potash feldspar is especially valuable
and the minerals are mined and used in the manufacture of porcelain.
Graphic granite is also abundant. Of the micas, a dark biotite is more
common than muscovite. It is often chloritized and it is with this
altered mica that the rare minerals fergusonite, gadolinite, etc., are found.
The descriptions of the rare earth minerals, largely historical, include
also yttrotantalite, allanite, xenotime, and altered zircon.

W. T. SCHALLER

Rastatt, R. H. ‘The Skiddaw Granite and Its Metamorphism,”’
Quart. Jour. Geol. Soc. (London), LXVI (1910), 116-41. Map.

A study of the alteration produced in the sedimentary rocks of
the Skiddavian Series by the intrusion of an alkali granite commonly
known as the Skiddaw granite. The metamorphism extends over a
considerable area, although the outcrops of granite are limited to three
of rather small extent which the author supposes to be part of a large
mass continuous beneath the surface. From the repetition of the same
sequence of rock-types in reverse order, it appears that the structure of
the region is that of a complicated anticline or syncline, the former
being most probable. The position of the granite mass suggests that
it was intruded along the main axis of this anticlinorium, and the author
believes its injection closely followed or even accompanied the folding.
If this is true, here is an example of a direct relation between intrusion
and folding. The chief minerals produced by the metamorphism were
cordierite, andalusite, biotite, and muscovite, with garnet and staurolite
near the granite contact. The absence of cyanite and sillimanite indi-
cates that the rocks were never subjected to a very high temperature, and
all the evidence points to the maintenance of a moderate temperature
for a long period of time, such as would result from the intrusion, under
a thick cover, of an igneous mass not very highly heated.

ALBERT JOHANNSEN

183 PETROGRAPHICAL ABSTRACTS AND REVIEWS
SCHALLER, W. T. -‘Axinit von Californien,”’
XELVILL (core) 148:

A chemical and crystallographic description. The conclusion is
reached that axinite is composed of the two isomorphous minerals,
ferroaxinite, Al,B H Ca, Fe Si, Os, and manganoaxinite, Al, B H Ca,
Mn Si, Or.

Zeitschr. Kryst.,

AUTHOR’S ABSTRACT

SmitH, G. F. HeErBert. ‘‘A Camera-lucida Attachment for the
Goniometer,’’ Min. Mag., XV (1910), 388-89. Fig. 1.

The camera lucida is used for the representation of ‘‘light figures”’

on imperfect crystals with rounded or striated faces, and for the delinea-

tion of small crystals.
W. T. SCHALLER

WINCHELL, ALEXANDER N. “‘Use of ‘Ophitic’ and Related Terms
in Petrography,” Bull. Geol. Soc. America, XX (1910), 661-67.

A history of the term ophitic which was introduced in the literature
by Michel-Lévy in 1877. Originally defined as a texture characterized
by feldspars, peculiarly grouped, inclosing more recent diallage or augite,
it is at the present time used either in the original sense or applied only
to those textures in which the feldspar is inclosed by large anhedra of
pyroxene.

The writer believes the term should be applied to all rocks having
plagioclase in lath-shaped crystals which were formed before the ferro-
magnesian constituents, and suggests the term ‘‘poikilophitic”’ for that
texture which is at once ophitic and poikilitic.

Alfred C. Lane, ‘Winchell on Ophitic Texture,” Science, XXXII
(1610), 513, says: ‘ltiseems to me that’... ./a pyroxenie matroqis
an essential part of the idea of the ophites. JI am, however, quite willing
to give up the idea that the augite must necessarily be altogether in

larger grains than the feldspar.”’
ALBERT JOHANNSEN

REVIEWS

Die Weltkarien-Konferenz in London im November, 1909. By
ALBRECHT PENCK. Zettschrift der Gesellschaft fiir Erdkunde.
Berlimeeroross eps ri4—27..

This paper states briefly what was done at the international confer-
ence held in London in November, 1909, looking toward a map of the
world on a uniform scale of 1:1,000,000. Starting with the inception
of the idea at the Bern meeting of the International Geographic Congress
in 1892, past efforts which have led to the present stage are reviewed.
The main features of the resolutions adopted by the London Conference
were:

That all nations participate in a world map of 1:1,000,000 scale
with uniform symbols; that the size of the sheets be uniform; that each
sheet cover 4 degrees of latitude and 6 degrees of longitude (except
that north of 60° N. lat. and south of 60° S. lat. two or more sheets of
the same zone may be united); that each sheet have an international
designation, as North B 12; that the latitude of the sheets be repre-
sented on each side of the equator to latitude 88° by the letters A to V,
and distinguished as ‘“‘North”’ or “South”; that each polar chart be
designated Z; that the longitude in units of 6° be represented by the
numbers from 1 to 60, the count beginning 180° from Greenwich and
proceeding from west to east; that in projection, the meridians be
straight lines, and the parallels be arcs of which the middle points lie
on the prolongation of the middle meridian; that the elevation of the
land be represented by a color scale using too-meter contour division
lines for regions of ordinary relief.

In addition to these leading features the recommendations treat of
a great many details upon which decisions were necessary in order to
secure uniformity of results in the completed map.

While further consideration and conference will be necessary to
determine who shall make the different maps, this conference has
prepared the way for the adoption at an early date of a common plan of
operations. This important enterprise now seems to be fully under
way.

RRS:
189

190 REVIEWS

“Prospecting in the North.” By Horace V. WINCHELL. The
Mining Magazine, Vol. III, No. 6, p. 436. December, 1910.

The writer compares the sulphide ore deposits of the western part
of the United States and Mexico with those of British Columbia and
Alaska and notes the differences in the operations of the processes of
superficial alteration and secondary enrichment in the different latitudes.
In the more northern deposits the metals have not migrated in cold
solutions so extensively, because the colder climatic conditions are less
favorable. Further, the secondary ores, where found, have generally
been planed off by ice erosion.

Since glacial times, at some places, a kind of secondary sulphide
enrichment has taken place at the very surface, but generally this
amounts to little more than a veneer or varnish on the lower-grade
material. His conclusions, applied to deposits of sulphide ores of
copper, silver, lead, and to some extent, of gold, are: ‘‘(1) Boreal
regions seldom contain rich and extensive deposits of secondary ore.
(2) The surface appearance is often deceptive, and if the ore is high
grade, sudden decrease in value may be expected at limited depth. (3)
Where large deposits of primary ore are found in glaciated regions, these
are likely to extend downward.’ In the temperate zone, “‘(1) Deep
superficial alteration and complete oxidation of vein-matter is a common
phenomenon in warm countries and is indicative of good ore below;
(2) In general, ore deposits are more abundant in the warm and tem-
perate zones; and (3) They are not so likely to terminate suddenly or
change rapidly in depth.”

Geological and Archaeological Notes on Orangia. By J. P. JOHN-
SON. London: Longmans, Green & Co., tg10. Pp. 99.

This volume contains chapters on Stratigraphy, Kimberlite Dikes
and Pipes, Diamond Mines, and Superficial Deposits and Pans.

Almost the whole surface is made up of nearly horizontal beds
belonging to the Karoo System, with comparatively small outcrops of
older formations along the Vaal River. In the area best exposed these
older beds dip away from a central core of granite and are overlain
unconformably by the Karoo.

The lowest of the Karoo beds is the Dwyka series, which is described
as a band of bowlder shale. The underlying rocks wherever exposed are
polished and present the characteristic contours of a glaciated country.

REVIEWS IOI

The evidence of the striations indicates a general movement of the ice
from northeast to southwest. The Ecca or Beaufort series, consisting
of fifteen hundred feet of sandstone and shale, occupies most of the
surface, while the Stormberg series is found along the eastern border.
The whole area of Orangia has been intruded by a network of basic
dikes and sills of nearly the same composition, and at a later date by
the veinlike pipes and dikes of the diamond-bearing rock. This rock,
which is known as Kimberlite, has a wide distribution in Orangia, fill-
ing both narrow fissures and vents or pipes. Its nature is as yet imper-
fectly known, some occurrences giving the impression of a consolidated
igneous rock, others being apparently purely fragmental. The author
thinks that the typical fissure Kimberlite is a magmatic intrusion, and
that the pipes were originally filled, perhaps on more than one occasion,
with a magma, which, except near the depth of origin, must have had
a very low temperature for an igneous extrusion and which, after solidi-
fication, was smashed up by frequently repeated explosions.
Be Re

The Slates of Arkansas. By A. H. Purbvs, with a Bibliography
of the Geology of Arkansas by J. C. BRANNER. Geological
Survey of Arkansas, 1909. Pp. 164.

The part of this volume which is of greatest general interest is chap.
iii, which deals with the geology of the slate area. This area includes
the part of the Ouachita Mountains from Little Rock westward for
about one hundred miles. The sedimentary rocks of known age are of
Ordovician and Carboniferous (Pennsylvanian) age, with rocks of
unknown age both above and below the Ordovician.

Above the rocks of known Ordovician age is a group of three forma-
tions of which the well-known Arkansas novaculite is the middle mem-
ber. In a former publication of the Survey these were all classed as
Ordovician, but the author finds no proof of this and thinks that they
may be Ordovician, Silurian, or Carboniferous.

The region is one of intense folding, and thrust faulting is quite
common. ERE;

Geological Survey of Georgia. Bull. No. 23, ‘‘ Mineral Resources.”
By S. W. McCattirg, State Geologist. Pp. 208.
The introductory chapter on the geology of the state is brief and
presents no new facts. The descriptions of the mineral deposits are
arranged alphabetically, the general distribution, the mode of occur-

192 REVIEWS

rence, the history of development and values being treated for each
type of deposit. In most cases no attempt is made to inquire into the
genesis of the deposits.

In a work of this nature whose value is chiefly statistical one would
expect a general summary and table showing the relative importance and
value of the various deposits, but none is found in this volume. Of the
ores of the state, those of iron are by far the most important. In 1907
they were mined to the value of over $800,000. BE. Reale

The Mining Industry in North Carolina during 1907 with Special
Report on the Mineral Waters. By JosEPpH HyDE PRATTY.
North Carolina Geological and Economic Survey, Economic
Paper No. 15>. 2p. 170.

The most important part of this paper is a report on the Gold Hill
Copper District by F. B. Laney (pp. 20-55). This district is located in
the south-central part of the state just west of the Yadkin River. The
rocks are slates and igneous rocks of various kinds, and of different
periods of intrusion. The ores are (1) auriferous pyrite and chal-
copyrite in a quartz gangue and (2) slightly auriferous bornite and
chalcocite in a quartz epidote gangue. No attempt is made to corre-
late the period or periods of ore deposition with a period of igneous
activity or to determine the age of the ores.

The remainder of the paper is chiefly statistical.
Ee Rese

Paleontology of the Coalinga District, Fresno and Kings Counties,
California. By RAtepH ARNotp (U.S. Geol. Surv. Bull. 396).
_ Pp. ror and plates 30.

The district forms a strip roughly fifty miles long by fifteen miles
wide along the border between the Coast ranges and the San Joaquin
valley. The eastern slope of the mountains is formed by a great thick-
ness of strata dipping toward the valley, successively younger formations
being exposed to the east. The rocks of the district range in age from
the Franciscan formation, which is probably Jurassic, to rocks of
recent age, with an unconformity at the base of almost every formation.
A description of the formations with faunal lists is followed by descrip-
tion of forms from the Tejon formation (Eocene), the Vaqueros, the
Jacalitos, and the Etchegoin formations (Miocene), and the Tulare
formation (Freshwater Pliocene).

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VOLUME XIX | NUMBER 3

THE

JOURNAL of GEOLOGY

A SEMI-QUARTERLY

EDITED BY

THOMAS C; CHAMBERLIN AND ROLLIN D. SALISBURY
With the Active Collaboration of

SAMUEL W. WILLISTON ALBERT JOHANNSEN WILLIAM H. EMMONS
Vertebrate Paleontology Petrology Economic Geology
STUART WELLER WALTER W. ATWOOD ROLLIN T. CHAMBERLIN

Invertebrate Paleontology Physiography Dynamic Geology

: ASSOCIATE EDITORS ‘
SIR ARCHIBALD GEIKIE, Great Britain GROVE K. GILBERT, National Survey, Washington, D.C.

HEINRICH ROSENBUSCH, Germany CHARLES D. WALCOTT, Smithsonian Institution
THEODOR N. TSCHERNYSCHEW, Russia HENRY S. WILLIAMS, Cornell University
CHARLES BARROIS, France JOSEPH P.IDDINGS, Washington, D.C,
ALBRECHT PENCK, Germany JOHN C, BRANNER, Stanford University
HANS REUSCH, Norway RALPH A. F. PENROSE, Philadelphia, Pa.
GERARD DEGEER, Sweden * WILLIAM B, CLARK, Johns Hopkins University
ORVILLE A. DERBY, Brazil - WILLIAM H. HOBBS, University of Michigan
_T. W. EDGEWORTH DAVID, Australia FRANK D. ADAMS, McGill University
BAILEY WILLIS, Argentine Republic : CHARLES K. LEITH, eae of Wisconsin

APRIL-MAY, 1911

CONTENTS

CERTAIN PHASES OF GLACIAL. EROSION
THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN 193

VALLEY FILLING BY INTERMITTENT STREAMS - - - = - - - A. E. Parkins 217

ORIGINAL ICE STRUCTURES PRESERVED IN UNCONSOLIDATED SANDS é
CHARLES P. BERKEY AND Jesse E. HypE 223

RESTORATION OF SENIORS Pe SLORENSIS PROUD, aN AMERICAN COTY—

ELOSAUR. =. =\ =. - - - S. W. WILLISTON 232
GEOLOGIC AND HSNO ele iB Swide IN: ole EB GON ABOUT CATCARA,
WV OEINGE ZU Ne ee one See IRS A. BENDRAT 238

THE «AGE OF THE TYPE EXPOSURES OF THE LAFAYETTE FORMATION
EDWARD W. BERRY 249

SRE GRIPPER Se Ok THE BEDFORD. AND BEREA FORMATIONS OF CENTRAL AND
SOUTHERN OHIO, WITH NOTES ON THE PALEOGEOGRAPHY OF THAT EPOCH
JEssE E. HypE 257

A POSSIBLE LIMITING EFFECT OF GROUND-WATER EON EOLIAN EROSION
JosEpH E. PoGUE 270

RECENTLY DISCOVERED HOT SPRINGS IN ARKANSAS - = - - “A. H. Purpue 272
SETTER LL RS A AR a eS i ly I alae a sears NPS hE Lee 97
PORPOLOCHKGAL ABSTRACTS SANDY REVIEWS... oe Mee) ee ee ee Re

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THE

FOURNAL OF GEOLOGY

APRII-MAY, rori

CERTAIN PHASES OF GLACIAL EROSION

THOMAS C. CHAMBERLIN anp ROLLIN T. CHAMBERLIN
The University of Chicago

Oscillation, more or less rhythmic, seems to be a phenomenon
of the intellectual, as well as of the physical world. The doctrine
of glacial erosion has its ups and downs in quite typical undulatory
fashion. It seems that even individuals at times ride on the
crest of the wave of advocacy and at other times sink into the
hollows of doubt. These moods are apt so to distribute them-
selves that while some workers are on the crest others are in the
trough. The crest-riders have recently been much the most in
view, but just now voices from the hollows of doubt are heard.
The president of the British Association for the Advancement of
Science, speaking from official vantage ground, voices a cautious
skepticism as to the glacial parentage of certain kinds of configurda-
tions that are held by others to be the erosive offspring of glaciers.*
Professor Garwood goes beyond the measured skepticism of Dr.
Bonney and gives a critical analysis of his grounds of doubt and
laudably matches his destructive criticism with constructive
interpretations. In these interpretations, he marshals topographic
phenomena in support of the view that protection? is the character-
istic effect of glaciers rather than erosion.

tT. G. Bonney, Presidential Address before B.A.A.S. (Sheffield, 1910), Science,
XXXII (1910), 321-36, 353-03.

2. J. Garwood, ‘‘Features of Alpine Scenery Due to Glacial Protection,” Geog.
Jour. (September, 1910), pp. 310-39.

Vol. XIX, No. 3 193

194 THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN

So, too, among those who believe in the efficiency of glacial
erosion, there has long been some doubt as to the truth, or at least
as to the adequacy, of some of the processes to which the erosion
has been attributed.

It seems worth while, therefore, to add to the growing mass
of matter some notes suggested by phenomena recently seen by
us, without presuming that much is new either in the observations
or in the suggestions. |

I. THE CRITICAL STAGE FROM WHICH CERTAIN EROSION TYPES
START

It has seemed to us advantageous to study the initial stages
of erosion to see, if possible, precisely what action gives the start
to the type of erosion which thereafter controls the configuration,
for it is the initial turn that most delicately measures the balance
between the opposing tendencies.

The contours that spring from ordinary wear and weathering
are well known and may be restored from remnants when the
greater part has been lost. Even when there has been no change
in the agent and only a slight change in its mode of action, the
old configuration can be distinguished from the new; as, for
familiar example, the remnants of a peneplain are commonly made
out with confidence after most of the plain has been cut away by
the rejuvenation of the very drainage system that formed it.
Much more clearly can remnants of contours be rebuilt into their
originals when some new agency intervenes, especially a new
agency whose habit of sculpture is distinctively at variance with
that of the previous agency.

As surface configurations are traced from regions dominated
wholly by ordinary wear and weathering into regions that have
been affected by local glaciation, it is usual to find the lower slopes
of the unglaciated region and, in the main, the brows and tops of
its hills and higher elevations, up to a certain limit,‘marked by
contours of the familiar wear-and-weather type whose interpreta-
tion is clear and whose restoration, when mutilated, may be made
with great confidence. As such contours are traced into higher
latitudes or higher altitudes where local glaciation has entered

CERTAIN PHASES OF GLACIAL EROSION 195

sparsely as a modifying factor, it is usual to find the flowing con-
tours of the wear-and-weather type replaced in certain spots by
a type that may be said to be unconformable to the prevalent one,
a type in which concavity replaces convexity, a type in which the
surface has been broadly scooped out locally rather than rounded
off generally or narrowly incised. ‘The broad scoop-like mode
of excavation, as distinguished from the gully-form mode of narrow
incision, is held to be distinctive in that it implies an agency that
deployed its effects laterally rather than one which concentrated
its action on axial lines. This, it is to be noted by way of precau-
tion, is a distinction that applies chiefly to the initial stage of the
two modes of erosion. They remain distinguished throughout
but are not so declaredly diverse in later stages.

The lodgment of snow, which is the primary factor in glacial
work and determines its initial deployment, is controlled by the
wind to an exceptional degree, and wind action is chiefly horizon-
tal in its effects and is thus distinguished from rainfall and run-off,
whose dominant actions are vertical. While the very first phases
of this difference of action are not very important in themselves,
they are believed to be significant as the initial factors in the
localization as well as the deployment of the two classes of erosion.

The relative locations of greatest rain-work and greatest snow-
work respectively.—Precipitation is intimately dependent on the
ascent of air so well laden with moisture that it reaches saturation
by reason of the expansion and cooling caused by the ascent. It
is for this reason that the ascent of moist air caused by rising over
the windward face of any marked relief of the topography deter-
mines precipitation on or near that face. As is well known the
windward sides of mountain chains thus receive more precipitation
than the leeward sides, as a rule. This holds true of snow-pre-
cipitation as well as rain, though the snowfall is less prompt and
less well localized. Where mountain ranges are broad and com-
plex the snow caught on the windward side is usually greater
than that which lodges on the leeward side, and the glaciers on
the windward sides of mountain ranges are usually larger than
those on the leeward sides. But such general community of
distribution does not hold in detail, for the wind comes in as a

196 THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN

local differentiating agency. Acting on rain, wind increases the
amount per unit area that strikes the surface of an eminence on
its windward side; it also somewhat increases the force of the
impact on that side. On the other hand, wind tends to drive
falling and fallen snow around the wind-swept side of the eminence
into its lee and to heap it up in the eddies there, and on the areas
protected from the wind. Thus the snowfall that, in the absence

Fic. 1.—Snow lodgment on the side of the summit ridge of Mt. Victoria, Canadian
Rockies. This ridge forms the continental divide. The snow has lodged on the
Eastern or Albertan side in the lee of the crest. Photo. by R. T. C.

of wind, would come to rest on the windward and lateral slopes of
an eminence and later must drain away on these slopes is, under
the action of wind, concentrated notably in patches in the lee.
Considered therefore in detail, rain action is somewhat intensified
on the windward side of prominences, while snow lodgment, leading
on toward glacial action, is more markedly concentrated on their
leeward slopes.

The field use of this distinctive localization of rain-work and
of snow-work respectively is qualified by the fact that, while the

CERTAIN PHASES OF GLACIAL EROSION 197

prevalent air movement of a region may be nearly constant in
general, the cyclonic movements that are the immediate agents
that bring on precipitation introduce variation in the particular
direction from which the wind blows at the critical time when the
storm is on and the distinctive work in question is done. In the
mid-latitudes of the northern hemispheres, the general air movement
is toward the east but at the times of storms the wind not uncom-
monly comes from the eastward. However, the general law that
snow lodgment is most abundant on the prevailingly leeward sides
of prominences seems to hold good. This is greatly aided by the
shifting that takes place in the intervals between storms.

The fact that the eddies formed in the lee of crests, domes,
and knobs are the common spots of lodgment carries as a corollary
the observation that the forms of the snowfields are usually broad,
or ovoid. The windward edge is usually arched, and is often
thickened near its upper border. Not unfrequently the thickened
snow mass is wider transversely than in the line of slope. Often,
too, it must be noted, the lodgment is concentrated in ravines and
valleys that were shaped previously by drainage erosion, and in
such cases the localization is less distinctive.

The case best suited to a discriminative study is a broad or
transversely elongate lodgment of snow in the lee of a well-rounded
eminence from which the normal run-off is divergent. So long as
such a snow mass lies passively where it lodged, there can be little
doubt that it is protective rather than erosive, when compared
with normal surface action. So long, too, as the later action is
confined to a slow annual melting of the snow and a quiet run-off
of the resulting water, the snow and water combined perhaps do
less erosive work, on the whole, than would be done by the more
forceful impact and the more prompt run-off of the equivalent
rain, though qualifying conditions must be recognized on both
sides. .

The case of snow vs. rain, under these conditions, is not more
than debatable at most and the modes of erosion in the two cases
are essentially identical.

But when the snow accumulates perennially so as to move as
snow-ice in glacier fashion, the modes of erosion become diverse,

198 THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN

and the configuration of the eroded surface is the test of the domi-
nance of the one or the other type. It is obvious that the least
eroded part of the eminence must come to stand forth and the

Frc. 2.—Diagram to illustrate the effect of erosion upon a hill, on the assumption
that the capping of ice, SC, is protective. The dotted line represents the original
outline of the hill; the solid line, the contour resulting from erosion.

most eroded part must retire toward the center. If the snow-
covered flank or brow is indeed a protected area, it must gradually
come to stand forth from the retiring wear-and-weather contours

Fic. 3.—The same hill as in Fig. 2, eroded according to the hypothesis that ice
is a superior eroding agent. SC represents the original snow bank which comes to
occupy a basin as erosion goes on.

adjacent, as a rather definite embossment, as illustrated in Fig.
2. As time goes on, the summit of the hill should migrate toward
this protected area and it should tend to become the summit,
while the snow-cap in turn migrates into its lee. A marked asym-
metry should gradually develop.

On the other hand, if the snow mass, accumulating from year

CERTAIN PHASES OF GLACIAL EROSION 199

to year, comes to take on motion as a glacial body, the erosion to
which its motion gives rise must take a form coincident with the
moving part of the snow-ice mass. The erosion is assumed to
be due to the adhesion of the snow-ice mass to the ground on which
it rests—to the soil and loose rock at the start, to the progressively
loosened and ground rock below later. A broad patch of soil and
loose rock coincident in form with the moving part of the snow
mass is first dragged away and the configuration of the scar is
distinctive of the action. If erosion beneath the moving glacier
mass continues the excavation will in time come to have the form
shown in Fig. 3. Such excavations are to be looked upon as
embryo cirques. They are found on the lee crests, brows, and
slopes of round-topped mountains known to have been subjected
to local glaciation. Less typical initial cirques are formed in
ravines where snow lodgment gives rise to glaciers.

If absolute certainty that there has never been any previous
glacial action in a given region is regarded as a prerequisite to
an irreproachable illustration of this class of actions, such a case
is difficult to demonstrate because the configurations left by the
older glaciations have often been so largely lost in the subsequent
sculpturing of the common wear-and-weather type that the absence
of previous glacial work is hard to prove in regions likely to have
been glaciated recently, but this is only a question between the
work of different glacial stages, not between glacial and aqueous
methods. But though a region has been subjected to previous
general glaciation, even rather recently, geologically speaking, the
typical effects of local glaciation on rounded contours are dis-
cernible much as in wholly unglaciated regions, for the con-
tours shaped by the general ice movement conform to the domi-
nant horizontality or the low inclination of such general ice move-
ments, while the lines of local ice movement are decisively down-
ward in conformity to the local slope.

These considerations are here put in the theoretical form, but they
suggested themselves almost as inductions during a summer trip
along the coast of Norway in 1909. ‘They arose naturally from the
abundant and instructive phenomena of that region, where former
glacial action merges into present action. The configurations

200 THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN

wrought by the older general glaciations do not seriously mask the
distinctive work of the local glaciation that has followed and is,
in some part, in action still. Broad excavations of the initial
cirque type are common on the brows and slopes of the rounded
mountains and on the islands that fringe this coast and on the
mainland itself. They seemed to us clearly to be more common
on the eastward sides of the islands than on the westward. The
initial types are chiefly the products of modern action; indeed in

Fic. 4.—Basins hollowed in a hillside by tiny glaciers. From the coast of Norway.
Photo: by ReL. C.

many cases the basins are still occupied by the snow-ice mass to
which their shaping is due. The whole series taken together
show various stages of the work of snow accumulation and earth
excavation. Small, relatively wide basins, scooped broadly from
hillsides, are variously occupied or empty according to altitude,
latitude, or other condition favoring snow accretion or snow wastage.
Their dimensions range downward to hollows not unlike pits
on the brows of drift hills and upward to mountain cirques of
typical form and magnitude. ‘They also range from mere cirque
heads to cirque heads with short glacial appendages and thence
on to longer and longer glacial tails until the peculiarities of the

CERTAIN PHASES OF GLACIAL EROSION 201

head-work in the cirques are lost in the more familiar body-work
and tail-work of the more accessible parts. Various stages and
transitions are shown in the accompanying photographs.

Fig. 4 shows five well-developed basins escalloped in a hillside.
The two hollows on the left are round and wide and terminate
below in well-defined platforms or steps at nearly the same level.

Fic. 5.—A concave scallop on the brow of a projecting embossment. Apparently
this is the work of sapping by the ice at the base of the cliff. Note the rounded convex
glacier-polished outlines of the rest of the embossment. In the background is the
Lyskamm, central Pennine Alps. Photo. by R. T. C.

They are approximately as wide as they are long, showing that the
ice which accumulated there has eaten its way in a distinctly
broad fashion into the rock slope on which it lay. The vertical
distance which any given part of the ice has moved its rock is
small relative to the total amount of transportation accomplished.
The work has been done very locally compared with the longitudinal
movement of typical water action. The next two basins continue
down the slopes to points much nearer to the sea. There has been

202 THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN

more advance movement of the ice here. The basin on the right
has become a glacial valley in an embryonic stage and the work
of water erosion seems to form a larger factor.

Sculpturing of similar sort is illustrated by Fig. 5, from the
Swiss Alps. The brow of a long spur descending from the Zwil-
linge has been scooped and hollowed in concave fashion by the
sapping action of glacier ice. Occurring in the midst of a still

Fic. 6.—The Glacier des Grandes Jorasses on the Italian side of the chain of
Mont Blanc. The ice has sunk its bed into the rocky mountain wall and worked
backward as implied by the distinct bench upon which it rests. Photo. by R. T. C.

strongly glaciated area, this case is interesting for the reason
that such sculpturing has been at work here for a comparatively
short time only. ‘The rounded rock contours below and to the right
of the hollow excavation have at no distant date been scraped and
polished by the larger glaciers descending from the peaks above.
The ordinary abrasive action of a moving body of ice is here
illustrated. But the much smaller mass of snow and ice at the
base of the cliff in the hollow appears to have operated in the very
different and more potent manner of basal sapping at the schrund
line.

CERTAIN PHASES OF GLACIAL EROSION 203

Fig. 6, from the chain of Mont Blanc, represents the Glacier
des Grandes Jorasses on the Italian side of the rugged mountain
mass of the same name. Other similar glaciers to the left and
right have etched their basins into the upper slopes of this great
mountain rampart. These glacier-filled basins are deeply sunken
and are as broad or broader near the base of their cirque walls
than they are farther down toward the ends of the present ice
tongues. At their heads they are terminated by precipitous
rock walls. Extremely precipitous cliffs come down to the Glacier
de Rochfort from the Aiguille du Géant and the col between it and
the Aiguilles Marbrées. From these rock walls behind the ice
there is a very decided change in slope to the gentle incline of the
glacier floor below. In just the same way there is a very abrupt
change of slope from the precipitous rocks of the Grandes Jorasses
and Mont Mallet to the very moderately inclined surface of the
Glacier des Grandes Jorasses at the foot of these steep cliffs. It
is at the point where these cliffs join the less inclined basin floor
beneath the glacier that the greatest cutting has occurred. Such
a profile of cliff and floor coming together at a sharp angle is quite
_unlike any gully erosion developed by ordinary running water in
mountains of massive crystalline rocks. The greatest cutting has
been beneath the glacier in the neighborhood of the bergschrund
and directed backward into the mountain.

II. CERTAIN SIGNIFICANT POSITIONS OF CIRQUES

In our sketch of the initiation of cirques, we gave preference
to cases located on leeward aspects of eminences favorable for
snow lodgment but unfavorable for the concentration of running
water. We noted that if the lee brow were protected by its snow
covering, the crest should slowly shift toward the protected spot
and the protecting snow-cap should shift in turn to its lee and thus
combine to shape forth an asymmetrical mountain horn. On the
other hand, if the snow mass becomes a superior erosive agent
when it begins motion, and digs out a broad basin which in turn
adds to the catchment of snow, and if at the same time the embry-
onic glacier stopes headward, it, in its way, moves toward a summit
position. It is clear that rainfall does not concentrate toward

204. THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN

the summit of a rounded eminence in this way. Its trenches do
advance headward, but they take the form of ravines, gulches,
and gullies eating sharply, not broadly, backward. ‘The positions
of cirques that are fully developed may be studied for evidence
confirmatory of these deductions. In such study perhaps the most
striking illustration of summit-ward creep is found in the crater
cirques, a form that has attracted the attention of observant
travelers but has not played as large a part in glacial literature as

Fic. 7.—The Rendalstind on the west side of the Lyngenfjord, Norway. The
summit has become crater-shaped by ice sculpturing. Photo. by R. T. C.

perhaps it should. Mountains with crater-like summits are quite
common along the Norwegian coast above the Arctic Circle, and
they are likewise frequent enough in the Lofoten Islands to give
characteristic profiles to the views obtained there from passing
steamers.

The Rendalstind, on the west side of the Lyngenfjord (Fig. 7),
is an illustration of the type in a not very advanced stage of develop-
ment. Glacier action in the summit basin is today actively
in progress. Other mountains of the region reveal much more
pronounced sculpturing of this sort where the action has either
been more prolonged or more intense. Such a case is illustrated by

CERTAIN PHASES OF GLACIAL EROSION 205

Fig. 8. This crater mountain, which happens to be crossed by
the 7oth parallel, comprises the north end of Kaagé Island. Origi-
nally it appears clearly to have been a more or less rounded dome
or knob. A cirque starting with snow lodgment high up on the
northeast slope of this eminence appears to have worked back

Fic. 8.—A crater-like mountain top in a more advanced stage of erosion. The
outer slopes of the conical mass show the familiar abrasive action of past general
glaciation together with the lines of ordinary meteoric erosion. The steep walls of
crater-like cirque are due to sapping by localized glaciers of late date. Kaagé Island,
coast of Norway. Photo. by R. T.C.

toward the summit by a stoping process until the cirque pit has
come to occupy a sub-summit position. The mountain top has
been hollowed out and now only a shell remains in place of the
former flat-topped mass. It is like a volcanic crater broken
down on one side. The inner walls are steep and cirque-like and
the crater portion is filled with deep snow. Water erosion is not
adapted to this sort of sculpturing. The central basin with cir-
cular cirque cliffs gives every appearance of having resulted from

THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN

206

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-[ND oY} WoIZ JSvayINOs SUIxOo] Useg ‘opeIO[OD Jo sureyunoy uenf ues dy} ur onbs1 yrurums snoredvs Alaa W—'6 ‘O1g

CERTAIN PHASES OF GLACIAL EROSION 207

continued sapping and quarrying by glaciers eating their way
backward much as they have in the Alpine cases cited.

Fig. 9, from the San Juan Mountains of southwestern Colorado,
is a striking example of a much more capacious summit cirque.
The basin here is very broad, with a nearly level floor, while the
cirque rim has been undercut till only a narrow horseshoe-shaped
serrate ridge remains. Its jagged crest varies in altitude from
13,000 to 13,200 feet, while the mean elevation of the broad floor
is about 12,800 feet. The breadth of the basin and the steepness
and thinness of the amphitheater walls that skirt it show that
this type of action has here gone about as far as it well could as a
single stoping operation. The whole constitutes a signal case at
its very climax.

In the light of these illustrations, particularly Figs. 8 and
9, there seems no ground to doubt that the erosion suffered by
the non-glaciated parts in such situations at least falls greatly
behind that suffered by the parts covered by ice.

III. THE DISTINCTIVE WORKING FACTOR

The decided superiority of moving ice over moving water as
an erosive agent lies chiefly, we think, in the rigid hold of the ice
on matter set in its base or sides. This is sharply contrasted
with the adhesion of water which is so feeble as to scarcely warrant
the term “hold” at all. Water action finds some compensation,
indeed, in the higher velocity it usually gives to the matter it
carries, but near the point of origin of action—and this is the
location chiefly under discussion here—the water is so distributed
as not to be able to acquire much efficiency from concentration.
The ice mass, on the contrary, is rigidly unified; its velocity is
indeed low, but its mass and fixed coherence are high. It is in
respect to this coherence that exaggerated views of the viscousness
of ice are perhaps most misleading. Rigidity of grasp and mechani-
cal firmness of action are specifically implied in the groovings,
gougings, and crushings that distinguish the action of glaciers.
Effectiveness of corrasive action is further implied in the chemical
and physical nature of the rock-flour and fragments which these
groovings, grindings, and crushings contribute to the glacial till

208 THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN

and to the wash-products immediately derived from it through
glacio-fluvial assortment.t The graving of a glacier’s bed by
rock fragments set in its base or sides may be cited as specific
evidence of an essentially rigid hold on the graving tools, and of
an internally rigid, rather than fluent, motion of the mass holding
the tools. The glacial grindings that are borne out with the
subglacial waters and give milkiness to glacial streams seem to
us irrefutable evidence of effective rasping and grooving of the
rigid type, not of simple viscous overcreep. The very marked
contrast between the turbid waters that flow from beneath glaciers
and the relatively clear waters that flow down adjacent ungla-
ciated valleys is very impressive and spectacular evidence of the
superior erosive powers of glaciers.

Closely allied to this lesson from grindings in transit is a less
obtrusive one drawn from the contrast in the points where coarser
matter which only strong transporting agents can handle is con-
centrated respectively in glaciated and in non-glaciated valleys
in regions of the same general type. The upper parts of non-
glaciated mountain valleys in cold regions are usually burdened
with heavy talus and large loose masses which the drainage is
unable to carry away, while the glaciated parts of similar valleys
are usually well scoured out and the moutonnéed sides and bottoms
of U-shaped troughs take the place of the craggy outliers of V-
shaped trenches in unglaciated valleys. But in the lower portions
of the glaciated valleys below the reach of recent glacial action,
aggradation very generally prevails, while in similar non-glaciated
valleys degradation generally prevails, if not absolutely, at least
relatively. Students of Alpine regions will recall multitudes
of illustrations. A similar lesson is even more impressively
enforced on the borders of the late Pleistocene glacial areas. In
strong contrast to the state of the valleys of the adjacent driftless
regions, the great glacio-fluvial valley trains with their thick
heads next to the ice border, as well as the frontal aprons, show
very conclusively the overladen condition of the glacial waters and_
their marked incompetency to fully carry away their burdens.

= “Hillocks of Angular Gravel and Disturbed Stratification,” Am. Jour. Sci.,
XXVII (May, 1884), 378-90.

CERTAIN PHASES OF GLACIAL EROSION 209

Now the regional precipitation is much the same for like areas
and like situations in the glaciated and in the non-glaciated val-
leys. Such differences as there may be appear to favor a greater
run-off in the glaciated than in the non-glaciated basins, for the
former are likely to be cooler and hence better condensers and the
concentration of snow by wind action is there more effective. If so,
the advantage in absolute carrying power lies with the waters of
the glaciated valleys. If therefore the passing of a part of the
precipitation through the glacial form and the moving of this
part, so far as 1t moves as Ice, is protective, the débris should tend
to remain in the upper glaciated sections thus protected; while
the waters of the valley below the glacier having some excess in
volume and having less burden to carry should tend to degrade the
lower reaches of the valley more effectively than if the glacier were
absent. That the facts are precisely the opposite seems good
additional evidence that the glacial form of water compared with
the aqueous form increases notably the corrasion and the trans-
porting power. And so it seems to us that the fringing outwash
aprons and the thick-headed valley trains of the Pleistocene
join with the aggraded states of the lower stretches of present
glacial valleys and with their turbid glacial streams, their mouton-
néed walls, and their glacial scorings to testify to the superior
erosive efficiency of glaciers.

Traced back analytically to the properties that gave rise to
them, these corrasive products point to a glacier’s power to take
firm hold on rock fragments imbedded in its base and sides and
move them on while it uses them as graving tools. <A special
feature that is of interest here is the ice’s habit of freezing to
fragments in contact with it, especially when moisture is present.
Ice also strengthens its adhesions by a tendency to freeze and thus
to attach additional ice at points where tension is developed.
This amounts to an inherent tendency to strengthen its hold when
threatened with severance.

IV. THE EVOLUTION OF THE CIRQUE

In a young glacier-head just coming into action as the result
of the growth of its stresses as a snow mass, it is inevitable that

210 THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN

at some point near the upper edge of the snow mass there should
come to be a line of strain between the thicker part below that
is forced to move and the thinner part above that lacks sufficient
stress to take on motion. A low temperature is essential to the
preservation of the elements that enter into the process. Through
this low temperature the snow-ice mass has become adherent to
the soil beneath it and more or less interlocked with the loose
rock that may be at or near the surface. The motion of the snow-
ice mass involves the motion of some part of this underlying
material. Under the snow-protected stationary part the loose
earth-surface remains behind. The line of division between the
stationary protective snow and the moving abrasive snow-ice
mass thus demarks a scar and this scar, if we interpret aright, is
the embryo of the future cirque. As the process goes on and the
excavation becomes deeper and by this deepening comes itself
to aid in the catchment process, the line of transition from the
ineffectively thin snow above to the effective deep snow below
becomes more sharply defined. Thus the delimitation of the
growing glacier-head and its product, the growing cirque, not
only becomes more pronounced but the line of parting between
the active and the inert becomes fixed by the process itself; and
so the declared cirque becomes established and its bergschrund
localized. With further progress the action graduates into the
still more declared forms of the cirque-generating process.

In the exposition of Willard D. Johnson’ as also in that of
G. K. Gilbert,? both of which we accept in the main, the berg-
schrund is made the dominant agency in the cirque formation. The
view just outlined carries the cirque-forming action back of even
the cirque itself and, potentially at least, back of any bergschrund
or any possible influence arising from the bergschrund. It makes
the bergschrund and the cirque-development sequent on conditions
and agencies that at an earlier stage controlled the snow-ice accumu-

t Willard D. Johnson, ‘‘The Profile of Maturity in Alpine Glacial Erosion,”
Jour. of Geol., XII (1904), 569-78. Earlier papers are ‘“‘An Unrecognized Process
in Glacial Erosion,” Science (1899), p. 106; ‘‘The Work of Glaciers in High Moun-
tains,” ibid., 112-13.

2G. K. Gilbert, ““Systematic Asymmetry of Crest Lines in the High Sierra of
California,” Jour. of Geol., XII, 579-88.

CERTAIN PHASES OF GLACIAL EROSION PAMEAC

lation and brought on motion in the thicker part of the mass while
it left the thinner part stationary and protective. The berg-
schrund and the cirque cliff are themselves made. sequences of a
mobility and erosive competency more primitive than themselves.
This in turn is contrasted with adjacent inertness and erosive
inefficiency.

All this, however, seems to us wholly compatible with a cordial
acceptance of the bergschrund and the cirque wall as auxiliary
sequential agencies which strikingly abet the more primitive
actions that brought them into being. Much as the bergschrund
may aid the backward sapping of the cirque wall, we think that the
more fundamental agencies are to be regarded as controlling the
process throughout its history.

As already implied, a marked peculiarity of ice, shared in equal
degree by no other familiar body, is its tendency to grow under
tension and to form adhesions by such growth at the points where
tension has been developed. When forced to part, ice parts
suddenly by abrupt fracture attended by the elastic recoil of the
separated faces. In this its action is in marked contrast to the
separation of viscid bodies, which part by a gradual weakening and
stretching under continued strain. Within the bergschrund, as
also elsewhere and in general, the predisposition of the ice, when
at the critical temperature of congelation and below, is to freeze
to whatever falls in from the surface or is loosened from the walls.
This tendency to form adhesions is no doubt especially active at
the base of the schrund and at the foot of the cirque wall, where the
convergence of the walls wedges all such matter together and where
the conditions of temperature and moisture are likely to be favor-
able to glacial attachments in the active season. Whatever snow
falls in, slides in, or is blown into the gaping mouth of the schrund,
and whatever rock is detached from the cirque wall by the freezing
of such waters as may come down the bergschrund are subject to
such attachment to the head of the glacier and to removal by it
as it moves, as Johnson has indicated. In addition to this, such
waters as enter the mountain at any point above the cirque and
traverse internal joints and later come out to the face of the cirque ,
wall lower down are subject to freezing as they come near the

212 THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN

exposed portions of the face, and by expansion in the joints are
likely to rive the wall rock and to detach fragments from it. It
seems probable from the nature of the case that the exit of such
internal drainage takes place more largely at or near the foot of
the cirque wall than at higher levels. Such a localization of the
action is specially fitted to promote basal sapping. If the sapping
at the base of the cirque wall be thus made in some notable part
dependent on the seepage of water from the mountain mass at
or near the base of the wall, it will not perhaps seem strange that
the sapping should proceed somewhat downward as well as back-
ward, following in reverse the direction that the waters of seeps
and springs usually take in issuing, and thus give rise to the impor-
tant fact observed by Johnson that the floor of the cirque fre-
quently inclines ‘somewhat toward the cirque wall.t

In this view, the sapping is not made in any radical way depend-
ent on diurnal changes of temperature due to the openness of
the schrund above; rather it presumes that the base of the schrund
will often be filled with snow, ice, or rock fragments fallen from
above and that it will not be freely exposed to the briefer class
of changes of temperature that affect the outer air. It does
presume, however, that the mean temperature at the base of the
schrund, and at the base of this part of the glacier generally, favors
freezing whenever tension aids, and that it is favorable to glacial
growth rather than glacial wastage, as this is the general fact in
this part of a glacier. The periodicities of seasonal temperature
and the variations attending the cyclonic movements of the atmos-
phere extending over some days seem to us more probably effective
in the sapping at the base of the cirque wall than daily changes.

V. GLACIAL STEPS

Conditions somewhat similar to those of the cirque, save in the
matter of the beginnings of motion, are often found at other points
along the length of the glacier below the cirque. They do not
seem to be in any way dependent on the existence or the absence of
a declared cirque at the head of the glacier. If a glacier takes
origin in a sharp gulch or in a pointed valley, a typical cirque

* Willard D. Johnson, Jour. of Geol., XII, 576.

CERTAIN PHASES OF GLACIAL EROSION 213

may not develop, but this does not affect the behavior of the gla-
cier below. If a pre-existent step or down-set crosses the bottom
of the valley at any point beneath a glacier, or if a step is developed
by structural inequalities, and if the down-set is sufficiently great
in proportion to the thickness of the ice to cause effective crevassing

Fic. 10o.—View from the Baregg in the Bernese Oberland, Switzerland. At
the bottom of the picture below the ice fall is the comparatively level Lower Eismeer
of the Unter Grindelwald Glacier. Above the ice cascade is another higher ice plateau
known as the Fiescherfirn, limited by the slope seen in the perspective. Peeping
through the mists high above is the point of the Grosse Fiescherhorn. Photo. by
Rew Ce

through the whole depth of the glacier, the conditions at the base
of the step are not radically different from those at the base of the
cirque wall, for there is in effect a break in the continuity of the
motion of the glacier and the beginning of a new motion in the ice
mass below. The rock face of the step may be regarded as a
cirque wall in a modified sense. From it masses may be detached
and, falling against the ice wall, become attached and dragged

214. THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN

forward. At the brink of the step-wall special weighting is likely
to be brought to bear by the pushing of the ice forward over the
brink before it breaks and drops down, and this probably leads to
some splitting off of the edge of the wall. This action naturally
tends to give slope to the step and to modify it in the direction of
a cataract as distinguished from a cirque, but the essence of the
phenomenon is probably much the same in either case. Sapping
and stoping seem to be rather general phenomena of the basal
action of glaciers.

Fic. 11.—The Furgg Glacier, a broad, flat, ice sheet at the east base of the Matter-
horn. Both above and below, this nearly level glacier-made shelf are steep cliffs.
Photoyiby, Re dec:

The operation of the stoping process at several points in a long
glacier tongue, by developing successive ice falls between more
or less level stretches, results in a rude stairway of giant tread.
A portion of such a glacial stairway is shown in Fig. 10. This
is the Unter Grindelwald Glacier viewed from the Baregg. Two
comparatively level stretches of glacier are’ visible—one above the
prominent ice cascade, the other below it. They are known
respectively as the Fiescherfirn and the Lower Eismeer. Dropping
from the Grosse Fiescherhorn and lofty Fieschergrat to the gently

CERTAIN PHASES OF GLACIAL EROSION 215

sloping Fiescherfirn are steep ice-clad slopes—the upper cirque
walls. Dropping in turn from the Fiescherfirn to the Lower
Eismeer is the ice cascade in the center of the picture. To the
right beyond the range of this picture the level Eismeer plunges
over another ice fall toward the Liitchine valley below. The last
plunge, however, is perhaps more in the nature of a hanging valley
at the approach to the main valley. -Cataracts due to the fall of

Fic. 12.—Nearer view of the head of the level Furgg ice sheet and the Furggen
Grat, whose precipitous walls are being undermined. View from the Matterhorn
huts ehotos by, Real. GC:

glaciers from hanging valleys into main valleys are frequent but
necessarily occur at or near the junction of the valleys. Cataracts
occurring at intervals along the course of a single ice stream are
presumed to be correlated with stoping action.

Fig. 11 is introduced as an example of a flat plateau-like glacier-
covered tract intermediate between the mountain heights behind
it and the lower valley in front. This flat plateau covers an area
of approximately four square miles at a mean altitude of about
10,000 feet above the sea. Ice cascades descend toward the

216 THOMAS C. CHAMBERLIN AND ROLLIN T. CHAMBERLIN

lower valley from either end of it. Behind are the abrupt cliffs of
the Matterhorn and the Furggen Grat (Fig. 12). The very sharp
angle between the steep wall of the Furggen Grat and the Furgg
Glacier which is pulling away from it affords strong evidence of
the effectiveness of sapping at this critical location.

VI. BASAL SIDE EROSION

The sapping and corrasion along the side-base of a glacial
valley, by which the normal \-shape is converted into the glacial
U-shape, is perhaps due mainly to the better supply of carving
tools furnished the sides of the glacier by infall and inwash from
the slopes and cliffs on the valley sides, and by seepage from the
side walls. ‘This supposes a general similarity between the con-
ditions at the side of the valley and those at the cirque base,
except that the direction of glacial motion is different.

_ All these distinctive phenomena of glaciers seem to us to be
expressions at once of the peculiarities of glacial erosion and of
its superiority where conditions favor glacial erosion.

This view does not, however, make. the superiority universal
and unqualified. Obviously it does not exclude the view that
snow fields while they remain in the passive state serve as pro-
tective agencies. Nor does it exclude the view that the center
of a continental ice field, from which the motion is mainly radiant
and limited in amount, may be protective rather than erosive
when compared with normal weathering. Nor does it exclude the
view that valley glaciers in some of their parts may be less erosive
than normal wear and weathering would be. But these seem to
us rather qualifications of the general proposition that glaciers are
effective agents of erosion than contraventions of it.

VALLEY FILLING BY INTERMITTENT STREAMS

AE. PARKINS
Michigan State Normal College, Ypsilanti, Mich.

Streams having steep grades are usually thought to be in active
vertical erosion. The writer finds, however, that many inter-
mittent streams are not degrading but are actively aggrading
parts or all of their valleys. One of the best examples of such
valley filling is that of Jewell’s Creek, described in this article.

This little valley is found on the right bank of the Huron River
about two miles above the city of Ypsilanti. The Ann Arbor
sheet (U.S.G.S.) shows it as a mere ravine to the west of the little
settlement of Superior. The accompanying map shows that the
valley is about eight hundred and fifty feet long and that the head-
waters are eighty-five feet above the Huron River. The line mark-
ing the west boundary of the map is on the line of a fence. The
land to the west is under cultivation. The main stream has two
tributaries, one from the southwest which enters near the mouth,
and another from the northwest, joining .the main stream near the
_head waters. Both of these branches head into cultivated fields.

The main valley is divided into two distinct parts. Above
where the forty-five-foot contour line crosses the valley, the flow
of the water is intermittent. The floor is thereby mostly dry and
covered with a species of grass that can live under dry conditions
for part of the year. Below the forty-five-foot contour line the
flow of water is constant throughout the year. Here the bottom
is mostly wet and covered with swamp grass, which greatly retards
the flow of water. Fig. 2, taken from a point near the mouth,
gives a good idea of the lower part of the valley; while Fig. 3 gives
a view of the middle portion just above the crossing of the forty-
five-foot contour. The stump shown in the face of the small cliff
in the foreground is indicated on the map by the letter S, the trees
are indicated by circles, and the cattle are standing just about
where the fifty-foot contour line crosses the flat bottom of the

217

218

A. E. PARKINS

CONTOUR INTERVAL 5 FT.
SCALE
200 FEET

JEW BEES CREEK

(NV

By A. E. PARKINS

lone; ae

VALLEY FILLING BY INTERMITTENT STREAMS 219

valley. From both the pictures and the map we see that through-
out the whole valley we have steps and above each step the valley
bottom is flat floored. Only at one point in the valley, just below
the forty-five-foot point, is it V-shaped.

The flat floor indicates filling. This is best seen perhaps in
Fig. 3. This view also gives other convincing evidences. The
sharp angle between the valley sides and bottom is a good evi-

Fic. 2.—The lower part of the valley. In this part there is a continuous flow of
water throughout the year, it being below the water table. The water course is much
choked with grass. One step may be seen just this side of the tree, a walnut, in the
valley bottom near the middle of the picture. On the map the location of the tree
is designated by W. T.

dence, the buried ‘‘feet”’ of the trees is another, and the most
convincing of all is the position of the stump in the face of the
bank or cliff. Just above the roots, where the surface of the
ground is found with most trees, is a dark layer of soil about three
inches thick. This marks the level of the valley bottom before
filling. The view also shows that active erosion is going on at this
point causing the step to recede up stream. This recession takes
place only during and after rain storms and wet weather in the
spring. The material taken from here goes to build up the steps
in the lower part of the valley.

220 A: EE). PARKINS

But where does the materia] come from that is filling the valley
above this step and all the way to the headwaters? All over the
valley floor above this point we find fresh sand and gravel. Since
there is no evidence that it comes from the sides, it must come from
the collecting basins drained by the headwaters of this stream.

Fic. 3.—A view of the middle part of the valley. The forty-five-foot contour
crosses on the edge of the tiny cliff. This view shows the flatness of the floor, the
sharp angle between the valley sides and bottom, the buried “‘feet’’ of the tree and
the stump.

The fact that the headwaters lead from cultivated lands leads one
to suspect that here is the source of the material, and that the
valley began to be aggraded when the forests were cut off and
the soil loosened by the plow. This being so, filling must have
taken place since the arrival of man in this section. Just how
long ago that was, is not easy to determine from anything in the
valley, except what evidence may be, presented by the stump.

VALLEY FILLING BY INTERMITTENT STREAMS 221

Evidently that seventy-five- or eighty-year-old tree started as a
sapling in the valley bottom when the surface was two and one-
half feet below the present surface and on a level with the upper
portion of dark soil. Filling must have taken place some time
within the seventy-five or eighty years. It is probable that filling
has extended over many years and was and is necessarily inter-
mittent during the year and intermittent during periods of years,
less waste being furnished when the field to the west is in sod and
during the dry periods of the year.

If all these suppositions be true, one would be led to make the
statement that all valleys of intermittent streams that head in culti-
vated fields are waste filled. ‘To test this generalization search was
accordingly made and within a quarter of a mile from Jewell’s
Creek three others were found that showed essentially the same
features as here described. Later, other valleys were examined,
in all about a dozen, and invariably it was found that where these
streams headed in cultivated fields filling was going on in the
valley, the amount of filling depending upon the size of the collect-
ing area and upon the kind of material. Not all showed steps as
we have in Jewell’s valley, but in most of the valleys this feature
was duplicated. It was found that the steps were probably pro-
duced by bowlders or brush accumulating in the valley, causing a
deposit of leaves and waste on the up-side.

The steps in Jewell’s Creek as a rule are higher than any in the
other valleys yet examined. The ones that are higher show evi-
dences of their being in rapid though intermittent recession, and.
from indications on the sides of the valley it is believed that they
started farther down the valley where stones and twigs blocked
the course of the stream. How could the higher steps be produced
then? Let us imagine that we have a gradual slope to the valley
floor above this point of blocking, and that at some points the
water in times of flood had broken through the grassy cover of the
slope and had gouged out a trough with a tiny cliff at the upper
portion, as we see just to the north of the walnut tree in both
picture and map. Now by recession of this tiny step the cliff at
the edge would become higher and higher because the new valley
bottom produced by erosion would have less grade than the pre-

229 A. FE. PARKINS

vious one. - This seems to be the way in which the cliff in Fig. 3
was produced.

From a study of the ten or twelve valleys examined I think it
is possible to make the general statements: that valleys of inter-
mittent streams which head in cultivated fields are generally flat
floored due to filling; that the filling is intermittent, being affected
by kinds of crops, and wet and dry periods; that such valleys are
usually characterized by steps; and that these steps are first
caused by dams of stones and brush, and may become higher by
recession. In all such valleys we have an interruption in the
normal cycle of erosion, caused by an increase in the supply of
waste brought to the headwaters; and when this supply is decreased ~
the stream will clear away the waste and erosion will go on agree-
able to the normal order.

ORIGINAL ICE STRUCTURES PRESERVED IN UNCON-
SOLIDATED SANDS

CHARLES P. BERKEY anp JESSE E. HYDE

The purpose of this paper is to describe and illustrate certain
structures occurring in unconsolidated sands of glacial origin.
These structures are so inconsistent with the usual behavior of
sands during accumulation that it is believed they point to special
conditions that could have prevailed only during the glacial epoch.
It may be that they give a clue to marginal structures within the
moving ice sheet itself.

The deposit is located in New York City between 134th and
135th streets, west of Broadway. It may be seen from the River-
side viaduct which crosses the Manhattanville depression. It
appears as an irregular sand and gravel hill, probably only the
remnant of a once much more extensive deposit. While it has
been opened at several points to obtain building sand and abnor-
mal features are to be seen in several of them, recent excavation
for a building at the corner of 135th Street and Broadway has
revealed the most interesting exposures.

With the exception to be noted, assortment of material is
excellent. Sands of a wide range in size are extensively repre-
sented, usually well assorted and plainly stratified. Rarely the
finer silts and clays occur in interstratified streaks. On the other
hand, some of the beds are made up of pebbles whose diameters
are measured in inches. On the whole the materials are coarse,
i.e., sands and gravels rather than silts and clays. The individual
layers are usually thin, a few inches only, but some of the finer-
grained beds may reach a foot or two in thickness.

The exception to this rather thorough assortment of materials
is found in masses of bowlder clay which are intimately associated
with the other types. The bowlder-clay structure is very coarse.
Bowlders two or three feet through are not unusual and one over
six feet in diameter is closely associated with sand and gravel.

223

224 CHARLES P. BERKEY AND JESSE E. HY DE

Fic. 1.—Assorted sands and gravels standing as steep as 68 degrees at some
points. Left is northerly.

Fic. 2.—Contorted sands associated closely with coarse and unassorted gravels.
Right is northerly.

ORIGINAL ICE STRUCTURES IN SANDS 225

The occurrence of these strikingly unlike deposits so closely inter-
related is a prominent feature. Conditions suitable for the hand-
ling of large bowlders and the accumulation of till cannot well
_ be regarded as consistent with thorough assorting and deposition
of finely stratified sands at the same time and place.

The beds almost never lie flat; when they do it is only for a
few inches. They are almost invariably inclined toward the
north, northwest, or northeast; that is, against the general ice
movement as indicated by striae of the vicinity. Although the
maximum angle of repose for unconsolidated sands under sub-
aerial conditions is about 34°, the dips here commonly range from
HOmaUMEOUeh= 20%, 30;,,40., to 60. Inclinations of 68° and 71
have been observed and at one point, for a vertical height of four
or five feet, the beds are perpendicular or even slightly overturned."

Occasionally contortion is observed
but only to a very limited extent. a y
Baulting: of several imches displace- 025)
ment has been seen in such form that
it could not possibly have happened
by slipping on the growing margin of oe
a delta deposit. In one instance the Fic. 3.—Small overthrust in
necicnonnc chen midevot cto taut dip unconsolidated sands, thrust from

a general northerly or north-
away from the fault plane, on the westerly direction.
one side at an angle of 67°, on the
other side at an angle of 40°. In another instance a small thrust
fault of an inch displacement was observed. It is of significance
that the thrust was from the north (Fig. 3).

In order to explain these occurrences and the ones to follow, it
may be assumed that the deposit was laid down near the margin
of the ice sheet. The material is so well assorted and the bedding
is so sharp that it is necessary also to conclude that the deposit
was originally water laid. Possibly the dips were originally toward
the ice sheet as they are now found, but the angles of inclination
could not have been as great as they are now.

t Similar structural features are noted by Professor T. C. Chamberlin in gravel
hills in Tippecanoe Co., Indiana. (‘‘ Hillocks of Angular Gravel and Disturbed
Stratification,” A.J.S., XX VII [1884], 378-90.)

226 CHARLES P. BERKEY AND JESSE E. HYDE

It seems necessary to assume that, following the deposition,
and while the whole mass was thoroughly saturated with water,
it was frozen and incorporated in the ice and that there was then

Fic. 4.—A fine sand layer which seems to have been arched since deposition
and in the process developed V-shaped notches along the stretched upper margin
which are now filled with coarser sand. See explanatory sketch, Fig. 5.

Fic. 5.—Explanatory drawing to accompany the photograph, Fig. 4

movement of the ice sheet with its included material. The move-
ment in the latter, while probably not great, was sufficient to cause
the oversteepening of the sands as they are now found, and the
slight amount of contortion and faulting which occurs. Under

ORIGINAL ICE STRUCTURES IN SANDS 227

these conditions probably the interstitial ice became an efficient
binder between the individual sand grains and caused the whole
to behave as a rock mass, yielding slowly to gradual stresses and
breaking or shattering or faulting like a true rock when subjected
to sudden changes.

Subsequent melting of the ice left everything in place, and the
whole complex mass suffered so little distortion from shrinkage
with the loss of its ice matrix that these secondary structural
features are still preserved.

With this statement of the thesis some of the minor structures
may be described. All of them occur in the finer sand deposits
exposed in the excavation at 135th Street and Broadway.

On the south wall there is a low regular arch several feet across
in a bed of soft fine clayey sand, perhaps eight inches thick. It
is overlain and underlain by much coarser sands. In the upper
part there are three narrow vertical cracks some three or four
inches deep where the fine sand has been pulled apart, as if by
stretching, and the coarse material from above has filled the open-
ings. In this case, the difference in the constitution of the two
beds seems to have been a controlling factor and the two types
of material behaved somewhat differently, the fine-grained sand
layers moving as a unit, and cracking on the upper stretched
surface of the arch. The fine sand is now so soft as to be easily
pared with a knife and the coarse material runs out from above
and below it by its own weight.

At one point on the north wall of the excavation, and less per-
fectly at several other places, the sand preserves what seems to
be the original shattering and cracking of the frozen mass. It is
in very fine-grained sand, easily trimmed down without dulling
a knife blade. The fracture lines are decidedly darker than the
mass of the sand, sufficiently so to bring out the structures in the
accompanying photograph. The original sedimentary structure
of the sand is preserved and shows distinctly to what extent the
whole was crushed and faulted. It is in fact a sand deposit brec-
cia of extremely complicated structure.

A few feet distant from the last, a wholly different structure
is preserved. This is in quite fine-grained, clayey sands which

228 CHARLES P. BERKEY AND JESSE E. HYDE

Fic. 6.—Brecciation and minor faulting in unconsolidated stratified sands. For
explanatory sketch of the detail see the accompanying drawing, Fig. 7. Left is
northwesterly.

Fic. 7.—Explanatory drawing illustrating the most prominent detail of the
photograph, Fig. 6, and compiled in part from other photographs of the same occur-
rence. Only a few of the angular ‘‘fragments” of sand are indicated to show the
brecciation,.

ORIGINAL ICE STRUCTURES IN SANDS 229

alternate with several thin streaks of coarse sand, the latter seldom
exceeding an inch or two in thickness. These beds are inclined
at considerably more than the angle of repose under water, reach-
ing about 4o’, and have undoubtedly been oversteepened, although
scarcely distorted. Traversing this series is a thin, nearly hori-
zontal bed of rather coarse sand, six feet long and one to three
inches thick. This sand is for the most part horizontally bedded,
but cross-bedding also occurs, showing that it is undoubtedly
water laid in its present position. The remarkable thing is that
the cross-streaks of the inclined series are continuous above and
below this horizontal streak or layer and are interrupted by it,
showing that the horizontal bed came in subsequent to deposition
and oversteepening.

It is unquestionable that the beds above and below the hori-
zontal one were once continuous. Assuming them laid down,
frozen, and over-steepened as described above, it is postulated
that a horizontal crevice was formed in the frozen mass and melting
took place along it in the ice and that water currents of sufficient
force to carry and rearrange the sands were allowed to enter.
With the final thawing of the mass these delicate structures were
not destroyed and are still preserved in the unconsolidated sands.

Other occurrences in the same deposit exhibit irregular mixtures
of fine and coarse sands in which the finer-grained areas seem to
represent a bed that has been broken into distinct blocks or has
been drawn out into odd irregular stringers. This gives certain
areas, several feet across, the appearance of a coarse breccia in
which the finer sand areas constitute the angular masses, while
the coarser sands fill up the interstitial spaces like a matrix. Again
there are places where the oversteepened layers are so closely
associated with others whose attitude is consistent with present
conditions that the whole group almost baffles explanation in
detail.

In conclusion it may be worth noting that most of the structures
described and illustrated could not have been produced in these
sands in their present unconsolidated condition. The steeper
layers on the other hand could not have been originally deposited
in their present attitude. It is necessary to introduce some inter-

230 CHARLES P. BERKEY AND JESSE E. HYDE

mediate history. There is little doubt but that the oversteepen-
ing, the brecciation, faulting, and some of the mixing of materials
of different types were caused by glacial advance involving the

Fic. 8.—Photograph of the thin horizontal sand layer cutting inclined assorted
sands. Note the cross-bedding in the horizontal layer at the right. See explanatory
drawing, Fig. 9 below. Left is northwesterly.

Fic. 9.—Diagrammatic drawing to accompany photograph of inserted sand layer,
Fig. 8. The dotted area indicates the portion shown in Fig. 8.

whole mass in some way in differential movements. But before
that could be accomplished much of the material had to be assorted,
and this had been done, as the great variety and excellent sizing

ORIGINAL ICE STRUCTURES IN SANDS 231

of grains indicate, under extremely variable conditions and in
complex relations to unassorted masses. ‘This seems to point to
marginal and superglacial accumulation in such relation to the
general ice mass that the particles subsequently became incor-
porated with it and partook of its later movements. These later
movements developed the structures just described which may not
have been uncommon in other drift deposits but which are prob-
ably seldom so well preserved.

Although the original ice behavior is indicated by these struc-
tures it is doubtful whether the observations are of much value
toward a better understanding of ice flowage. ‘The ice must have
been unusually heavily saturated with these earthy matters, the
sands and gravels, and it is probable that differential movements
were largely encouraged by their differences of texture.

RESTORATION OF SEYMOURIA BAYLORENSIS BROILI,
AN AMERICAN COTYLOSAUR

S. W. WILLISTON
The University of Chicago

Few Permian vertebrates are of greater interest than the one
herewith figured, as restored from a remarkably complete speci--
men discovered the past year by Mr. Paul C. Miller in the vicinity
of Seymour, Baylor County, Texas. The genus and species were
originally described by Dr. Broili in 1904 from two imperfect
skulls, the clavicular girdle, and a few of the anterior vertebrae
and ribs, found on West Coffee Creek, Texas, and preserved in the
museum at Munich. Nothing whatever has since been added
to our knowledge of the genus, and the appendicular skeleton has
remained quite unknown. Of the numerous genera of amphibia
and reptilia from the Texas beds not a few are yet but imperfectly -
known, making it almost impossible to determine many of the
isolated limb bones and girdle bones so often found in those regions.
The past year I described various limb bones and vertebrae of a
small reptile discovered on West Coffee Creek under the name
Desmospondylus anomalus, suggesting its possible identity with
either Seymouria or Pantylus, especially Pantylus, which also is
known only from skulls, one of which is in the University of Chicago
collections. The two specimens upon which this genus was based
are of almost identical size, indicating that the specimens were
of adult animals. They prove, however, by comparison with the
later acquired specimen, to be congeneric, and of very immature
individuals, so immature that they present a number of embryonic
characters not seen in the adult specimens, for by the aid of the
articulated specimen others of Seymouria previously indetermi-
nable have been recognized among the material of the University
collections, all from the same region and horizon, the upper or
Clear Fork division. And these additional specimens have aided
materially in the production of the restoration because of their

232

RESTORATION OF SEYMOURIA BAYLORENSIS BROILI 233

facie

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234 S. W. WILLISTON

free condition. The specimen found by Mr. Miller was almost
completely inclosed in four pieces of a large clay nodule. All
that was visible in the specimen as it lay upon the hillside was a
small surface of the cranial table, where a chip had been broken
off.

The skeleton, as preserved in the nodule, is almost perfect,
save for the large part of the tail, which was inclosed in a pro-
tuberance from the main block, and the piece inclosing it doubtless
is still to be found in the wash where the scattered pieces were
secured. Nearly every bone is in natural articulation, the pha-
langes for the most part being scattered, some lost, others doubt-
less yet hidden in the matrix. Furthermore, the bones had suffered
almost no distortion or compression. The skeleton was fossilized
in a prone position and was somewhat depressed from its own
weight. The bones, however, inclosed in the hard, dark, red clay,
are rather soft, with a thin, white, cuticular, calcareous layer. So
far as possible the skeleton has been laid bare, but no attempt has
been made to separate any of the bones, nor could they be sep-
arated with safety. The occipital region of the skull, lying above
the clavicular girdle, is inaccessible, as are also the posterior ribs,
inclosed between the close-lying porrected femora and the verte-
bral column. Both hind legs are directed forward nearly parallel
to the vertebral axis, the feet pulled slightly away from the tibiae
and fibulae. The right fore leg also lies close by the side of
the body, the hand bones intermingled with the corresponding
foot bones. The left fore leg is directed forward. The pectoral
girdle lies closely in position, the left side pressed back a trifle,
and the pelvic girdle is almost perfectly in place. The skeleton,
to the sixth caudal vertebra, measures twenty-one inches. Because
of this natural position of the skeleton it has been a matter of little
difficulty to figure it in a restored position, the limb bones of other
specimens furnishing the proper views in the changed positions.
A full description of the form, with detailed figures, will be pub-
lished later. The figure here given, made with care by myself,
will furnish the most of the chief characters of the genus. Those
parts unknown or imperfectly known are represented by uniform
shading. ‘That the numbers of the phalanges as figured are correct

RESTORATION OF SEYMOURIA BAYLORENSIS BROILI 235

is practically certain because of the like numbers determined by
mein Limnoscelis; that the toes were slender is evident from several
isolated, unplaceable distal phalanges in the matrix. That the
tail could hardly have been longer than is represented, perhaps
not as long, is indicated by the taper of the six proximal vertebrae
preserved in position, folded down, like a dog’s tail, to the extremity
of the ischia. Two distal tarsals cannot be seen as covered by
the metatarsals; and the carpals cannot be clearly made out.

As a whole Seymouria stands lowest in rank among known
reptiles, approaching in many ways the contemporary amphibi-
ans. This is indicated by the structure of the posterior cranial
region, by the extraordinary amphibian ear-notch, by the primitive
structure of the vertebral centra, as shown in Desmospondylus,
by the long, free, caudal ribs, by the possession of a single sacral
vertebra, and by the very amphibian-like limb bones and girdles.
Indeed, so far as the characters are shown in the figure, there is
not a single thing to differentiate the form from an amphibian,
unless it be the apparent absence of the cleithrum. Unfortunately
the mutilation of the bone in the cranial table prevents the cor-
roboration of the temporal sutures as determined by Broili; but
I doubt not that Broili’s determinations are correct, showing all
the bones found in the temnospondylous amphibians and in similar
arrangement, some of which have never been detected in other
reptiles. The palate, also, as I make it out, is different from that
of other known reptiles, though distinctly reptilian in structure.
The pectoral and pelvic girdles are absolutely indistinguishable
from those of the contemporary amphibians, save by the more
posteriorly directed ilia and the absence of the cleithra, and both
of these characters may and probably will yet be found in the
temnospondyls.

The suture between the scapula and coracoid is very distinct,
quite in the position I have found it in other Texas reptiles and
amphibians; and the coracoid is composed evidently of but a single
element, the posterior element, the so-called coracoid, remaining
cartilaginous through life, as was also the case in Varanosaurus.
It is because of these facts, observed in several forms, that I am
quite convinced the coracoid as preserved corresponds identically

236 S. W. WILLISTON

with the coracoid of the lacertilia and rhynchocephalia, that is,
it is the true coracoid, and not the procoracoid. ‘To assume that
the coracoid of these animals has been replaced zu toto by another
bone, leaving only the supracoracoid foramen, which alone has
remained permanent, the bone surrounding it disappearing to give
place to another represented by cartilage, in some of the forms at
least, and far back of the foramen, is beyond the limits of my
credulity, whatever it may be for others.

In the structure of the skeleton of Seymouriza nothing is more
conspicuous than the extraordinary development of the arches
of the dorsal vertebrae, forming almost a carapacial protection
for the body. That the animal was crawling in habit there would
seem to be no doubt, notwithstanding the position in which the
hind legs were found—a position quite the same as that of the
type specimen of Limnoscelis. No indications of ventral ribs are
preserved and I think it may be said with absolute certainty that
the creature possessed none in life. On the other hand, scattered
through the matrix were numerous small flakes of bone, always
isolated. They may indicate osseous scutes. The teeth of the
creature are long and slender, utterly useless for the seizure and
retention of large prey. I think it very probable indeed that its
food consisted in large part, probably wholly, of the smaller inver-
tebrates, cockroaches, land mollusks, worms, etc., and that in
habit Seymouria was not unlike the modern land salamanders,
slow and sluggish in movement, hiding under fallen and decaying
vegetation in low and damp places.

The American cotylosaurs, more especially the Diadectidae,
Limnoscelidae, and Seymouriidae, show marked resemblances in
many ways to the contemporary amphibians, in their short legs,
broad feet, enormous humeral entocondyle, digital fossa of the
femur, pronounced adductor crest, as well as girdles; but I do
not believe that these resemblances were so much the result of
phylogeny as of convergent evolution, the adaptation to similar
environmental conditions and similar habits. Araeoscelis alone
among the known American Permian reptiles had a very slender
body and delicate, slender legs, adapted for climbing, or at least
for swift-moving upland habits. That there were many other

RESTORATION OF SEYMOURIA BAYLORENSIS BROILI 237

reptiles in Permian times of similar structure and habits is evi-
denced by Kadaliosaurus, among others. And all these must have
come from a common amphibian ancestry, so far back in Carbonifer-
ous times as to permit great structural diversity among both the
reptiles and the temnospondyls in early Permian times, too great
to warrant the assumption that all similar characters in the two
classes are the result of heredity.

The relationships of Seymouria are, on the one hand, closest
with Limnoscelis, on the other with Labidosaurus, but differing
so markedly from both as to merit a co-ordinate independent
position for the genus, which I prefer to call of family value—the
Seymouriidae. :

GEOLOGIC AND. PETROGRAPHIC NOTES ON THE
REGION ABOUT CAICARA, VENEZUELA’

T. A. BENDRAT
Turners Falls, Massachusetts

In the winter of 1908-9, the writer carried on some independent
studies along petrographic and geologic lines, in the interior of
Venezuela, choosing for his field of investigation the region imme-
diately west of the so-called ‘“‘El Caura District,’ at the famous
bend of the Orinoco, and mapping an area of 1,400 sq. km., which
was hitherto very little known. While the general results of this
survey have been summed up elsewhere,? it is on the main geologic
and petrographic features of the region that the writer wishes to
offer the following observations.

GEOLOGIC STRUCTURE
I. THE BED ROCK

The bed rock consists of a series of granites and gneisses which,
wherever they come to the surface, show a predominance of the
gneiss over the granite. These granites and gneisses rise from
the bottom of the Orinoco channel; constitute the base of many
of the islands; are exposed in the banks of the river, particularly
in the dry season; and back from the river form the bulk of the
‘““Cerros.”’ These cerros are hills and small mountains which rise
above the plain of the sabana. In general they increase in height
in proportion to increasing distance from the Orinoco, and may
be regarded as outliers of the Guiana mountain system lying to the
south. These cerros are probably to be considered as portions of
the great series of granites and gneisses which have most effect-
ively resisted disintegration, partly because a skeleton of numer-

«The writer desires to express at this place his high obligations to Professor

B. K. Emerson of Amherst College who was kind enough to have the petrographic
microscopes of Smith College, Northampton, Mass., placed as his disposal.

2Petermann’s Geogr. Mitteilungen (1910), Bd. 56, v; Geographen Kalender
(1909), 221.

238

NOTES ON THE REGION ABOUT CAICARA, VENEZUELA 239

ous veins and dikes cutting each other in all possible directions
traverses them.

An extended survey of the shores of Isla de Caicara, opposite
the village of Caicara, showed that the bed rock of this island is a
medium-grained granite of comparatively firm texture, which is
drab colored in fresh breaks, but which weathers to a purplish
tint. This rock shows cleavage planes extending north and
south, and east and west.

The cliffs exposed on the Caicara side of the stream by the
falling of the Orinoco during the dry season consist of medium to
fine-grained gneiss, whose laminations run either N.N.E.-S.S.W.,
or E.N.E.-W.S.W. Quartz veins, varying in thickness from three
to five inches, cut the gneiss in a general N.W.-S.E. direction.
It was on the surface of one of these rocks, about 1 km. north of
Caicara, that the writer discovered what, considering the latitude,
would seem a very curious phenomenon. ‘This consisted of three
grooves, about five inches long and one-eighth inch deep, which
run perfectly straight, one N. 80° E., and the two other S. 80° E.
They show a striking resemblance to glacial striae, but this does
not exclude the possibility that they may have been produced by
man, as in close proximity a series of the so-called ‘‘petroglyphics”’
was found, the grooves of which, however, were considerably
deeper and wider. The surfaces of the rocks on which the grooves
were observed were considerably smoothed, as were the rocks of
the banks of the Orinoco, but this might be due to the effects of
the currents.

The distribution of the granite and the gneiss in the hills
and ridges north of Cabruta and south and southeast of Caicara
also plainly reveals the prevalence of the gneiss over the granite,
for, with the exception of Cerro de Cabruta, north of the Orinoco,
and Cerro de los Spiritos, the lower portion of Cerro de Arinoza,
and possibly the whole of Pan de Azugar, all the cerros consist of
gneiss (see map, Fig. 1).

The Cerro de Cabruta, rising abruptly at its southwestern
terminus from the waters of the Orinoco to a height of about 290
meters above sea-level, trends, for a distance of about 12 km., in
a N.E. direction, and gradually falls off toward the llano plateau.

240 T. A. BENDRAT

The cerro is entirely made up of a coarse-grained feldspathic granite,
which weathers to a dull reddish purple, and in fresh cuts has a

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yellowish-white color. The yellow predominates over the white.
Toward the top, the granite becomes more and more quartzose,

NOTES ON THE REGION ABOUT CAICARA, VENEZUELA 241

while at the same time the quartz veins become more and more
frequent. Some of these quartz veins strike parallel to the general
cleavage planes, that is N. and S., while others run E. and W..,
and W.N.W. and E.S.E. The disintegration of the granite by
means of exfoliation was most strikingly exhibited on the top.
At one place a dike of gray to bluish-white quartz cut the granite
in a direction N.N.W. and S.S.E., which most probably determined
the initial direction of the southwestern spur of the cerro. Along
the line of contact, the granite seems to have become changed
locally into gneiss with lamination in a direction N.N.W. and
9.5.E. This was, however, the only instance of a gneissic phase
observed in the bulk of the granite.

Of the series of cerros on the southeast side of the Orinoco, the
Cerro de Caicara comes first and lies immediately south of the
village of Caicara. It rises to a height of 127 meters above sea-
level and extends about 2 km. to the south, along the bank of the
stream. It consists entirely of a more or less fine-grained gneiss
of light color, but on weathering becomes a dark purple. At
different levels the gneiss is highly charged with various grades
of iron oxide, which exhibit beautiful shades of color, ranging from
tan through ochre yellow to a dark bloody red. ‘The direction of
lamination is, in most cases, parallel to the general strike of the
rocks.

About 3 km. south of Caicara lies the Cerro de Arinoza, which
attains a height of 146 meters, while its foot is 71 meters above
sea-level. Only the lowest levels of this hill consist of a close-
grained quartzose granite such as was encountered in the Cerro
de Cabruta. The structure of this granite is in places pegmatitic
and the cleavage planes run N. and S., and E. and W., as do quartz
and pegmatite veins. Higher up in the slope, however, the granite
yields to a medium-grained gneiss, the laminations of which run
S. 20° E. and dip at an angle of 27° to the northeast.

The Cerro de los Spiritos is situated about 5 km. east of Pan
de Azugar, and nearly 8 km. $.S.E. of the village of Caicara.
About 200 feet high, it trends in a general N.W.-S.E. direction for
over 5 km. With a possible exception of Pan de Azugar, as
indicated above, it is the only cerro southeast of the Orinoco within

242 T. A. BENDRAT

the scope of the region under discussion which is entirely composed
of granite. It is of the coarse-grained feldspathic type and exhibits
joints which run pronouncedly N. and 8., E. and W., and N.W.—
S.E., and in no other direction. The backbone of the hill is a
quartz dike from 3 to 5 feet wide, which runs along the south-
western flank of the hill in a N.W.-S.E. direction. Assays made
of samples from this dike reveal traces of gold. Other quartz
dikes run parallel to this one as well as at right angles to it, while
near the top a dike of pinkish felsite about 2 feet thick and running
E.-W. stands out prominently from the surrounding coarse-grained
granite, which assumes a rather hornblendic aspect in the upper
levels. The flanks of the cerro, where slopes are gentle, and
only occasionally steep, are dissected by gullies and ravines running
parallel to the main quartz dikes in the main.

About 26 km. S.S.E. of Caicara the Cerro de Morano rises above
the plain of the sabana in two distinct knobs which have heights
of 375 and 3096 meters respectively above sea-level. Its topo-
graphic outlines seem to be determined by two main quartz dikes,
the more prominent one running N. and S., constituting the back-
bone of the cerro. Approaching the cerro from the north, one
encounters knobs and cliffs emerging from the sabana, which
consist of purplish weathering, coarse-grained feldspathic granite,
occasionally highly charged with iron oxides, and at places over-
lain by limited (in size) ‘‘banks” of ferruginous coarse-grained
sandstone. But the bulk of the cerro itself is made up of horn-
blende gneiss, which ranges from fine to coarse grained. The
average direction of lamination is N. and S., and N.W. and S.E.

2. THE SABANA DEPOSITS

In dealing with the deposits of the sabana, above which rise
the isolated cerros just described, one must distinguish between
the so-called ‘‘Laterite’’ deposit and what Dr. 5S. Passarge terms
“Upper Llanos” deposits.

1. The ‘Laterite’’ deposit—This deposit is a concentration of
iron oxide in a series of more or less fine and soft clays of a light
gray color. Deposits of this class have been found by Dr. 5S.
Passarge along the banks of the Cuchivero as well as the Caura,

NOTES ON THE REGION ABOUT CAICARA, VENEZUELA 243

and by the writer overlying the gneisses on the banks of the Orinoco.
As long as the deposit is under water or is stil] charged with water
after the streams have fallen during the dry season, it is very
pliable; but as soon as it becomes dehydrated, it turns extremely
hard and takes on the aspect of a clay ironstone. It has been

FIGS 22

called ‘‘Laterite,” and likened to the German “Zellinger Braun-
eisenstein.’’ The only true laterite portions form the upper part
of the clayey mass or are segregated from this. The clays are in
many places marbled by a more or less intense red. The deposit
directly and unconformably overlies the gneissic or granitic bed
rock. The deposit is not continuous and is frequently replaced
by a conglomerate, cemented by iron oxide (see Fig. 2). It occurs
inland as well as along the Orinoco.

Clays; loams, and sands

Fic. 3

2. The Upper Llanos deposits—The Upper Llanos deposits
which, as a rule, unconformably overlie the “‘laterite,’’ wherever
they have not been removed by erosion, may be said to consist
of the following three members: (1) A whitish or yellowish clay
which exhibits yellowish-brown cell structure, rich in iron; (2)
loams of various nature; (3) sands of different fineness and color.

Their interrelation changes with the locality and so do their
respective horizons. They constitute the upper portions of the
islands, as well as the upper terraces at an elevation of 50 feet,
approximately, above the average level of the lower terraces, and

244 T. A. BENDRAT

finally, the sabana itself. They lodge between the rocks of the
granites and gneisses, wherever these come to the surface, filling
in interspaces. The loam becomes very pliable and soft during
the rainy season, so much so as to allow mud turtles to plow
furrows from half a foot to a foot deep init. Local torrents some-
times carve channels down to the underlying laterite. The walls
of these channels become extremely indurated during the dry
season, rendering traveling across the sabana under such conditions
laborious, especially where there are no roads or paths available.

PETROGRAPHY OF THE GRANITES AND GNEISSES THAT CON-
STITUTE THE CERROS IN THE SABANA ABOUT CAICARA

I. THE GRANITES

The granites of the region under consideration comprise those
of the Cerro de Cabruta, the Cerro de los Spiritos, and those at
the base of the Cerro de Arinoza. A detailed microscopical study
of specimens taken from different levels shows that in all three
cerros the type of granite is essentially the same. This statement,
however, has to be modified in so far that, at one end of this ellip-
tic area, the granite is decidedly leukocratic while at the other it
is melanocratic. While the Cerro de Cabruta consists of a more
or less pronounced quartzose granite in its upper levels and its
top, the Cerro de los Spiritos reveals a decided predominance of
hornblende in the granite of its top.

Though described here in general terms as granite, this rock
is more correctly designated as quartz monzonite porphyry. Its
ground mass is made up of more or less angular or subangular
crystals of quartz and feldspar through which the leading miner-
als are sprinkled as phenocrysts. These phenocrysts are quartz,
which sometimes predominates over the feldspars, occasional
orthoclase associated with, or replaced by, microcline, the soda-
lime and lime-soda feldspars albite and labradorite, and finally
biotite, associated with or entirely replaced by hornblende.

Quite a number of quartz and feldspar phenocrysts show enlarge-
ment by secondary growth as revealed by zonal extinction or
by a more or less faint ring of dark material, apparently repre-
senting a coating of the original grain.

NOTES ON THE REGION ABOUT CAICARA, VENEZUELA 245

The frequent occurrence of a micro-pegmatitic texture suggests
conditions in the original magma that favored a simultaneous
crystallization of the quartz and feldspar.

Of the feldspathic minerals those of the soda-lime group appar-
ently prevail over the orthoclase (not so much over the microcline),
and among them labradorite is the one most frequently found.

The biotite occurs in lath-shaped crystals and in shreds and
flakes, the amphibole mostly with prismatic outlines, and only
occasionally in cross-sections. It was in such a cross-section that
an intergrowth of biotite and amphibole was observed, the former
penetrating the latter, clearly demonstrating their contempo-
raneous development. Apatite and titanite occur as inclusions
in the biotite, while the amphibole contains apatite and magnetite.
Microlites of biotite and apatite needles have been observed in
feldspar, while quartz carries magnetite, apatite, and occasionally
zircon. In cavities within the quartz liquid inclusions are some-
times present. Titanite is also found free in wedge-shaped crys-
tals, and considerable garnet, in more or less complete crystals,
occurs. Secondary minerals are calcite, which might have been
derived from some of the feldspars, and chlorite, which apparently
has come from the biotite.

Wavy extinction in quartz and feldspar; bending, breaking,
and slicing of feldspar and biotite; granulation of feldspar and
occasionally of quartz; and the complete crushing of titanite
crystals strongly suggest dynamic stress and shearing.

The occurrence of looped grains of orthoclase, and the more or
less advanced decomposition and the decoloration of a considerable
percentage of the biotite indicate katamorphic action, most prob-
ably by descending waters, while the secondary growth of min-
erals, involving zonal structure, and the formation of veinlets,
where crystals were broken, tell rather of the anamorphic activity
of ascending solutions.

2. THE GNEISSES

The gneisses of the cerros in the sabana of Caicara comprise
those of the Cerro de Caicara, Cerro de Arinoza, with the ex-
ception of its base, and those of the Cerro de Morano. A micro-

246 T. A. BENDRAT

scopic analysis of thin sections of samples taken from all levels of
these cerros, and a comparison of their composition, texture, and
fabric, tend to lend much weight to the assumption that the
gneiss throughout belongs to one and the same unit, as it was one
and the same type of rock we had to deal with in the granites.
This statement is, however, not intended to exclude the possi-
bility of local phases representing gradation and variation.

Like the granite, the gneiss is porphyritic. In a ground-mass
commonly of angular or subangular grains of quartz, with rather
fringed and dentated outlines, and of feldspars, especially micro-
cline and plagioclase, which usually are arranged with their longer
diameters parallel or slightly inclined to the plane of rock-cleavage,
are imbedded phenocrysts of pegmatite, microcline, albite, labra-
dorite, and biotite. All of these minerals, with the exception of
the biotite, are more or less allotriomorphic. Microcline seems
to take the place of orthoclase to a great extent, wherever the
latter is not intergrown with quartz, and we might say that the
predominance of microcline and pegmatite constitutes one of the
main features of this gneiss. Another feature is the frequent
occurrence of crossed lamellae in the plagioclases and a marked
tendency to form rather broad lamellae.

Of the feldspar and quartz the former is in excess. Among
the ferro-magnesian minerals, biotite, in phenocrysts of lath-shaped
form and in flakes, seems to be almost the only representative.
Hornblende is very seldom encountered, though in one instance
it was found intergrown with biotite.

Of accessory minerals an occasional crystal of pyroxene is
encountered, while magnetite and hematite are more frequently
met with. Garnets are not uncommon and wherever they occur
they are idiomorphic. Chlorite is present most probably as a
decomposition product from biotite and hornblende.

As regards inclusions in the different minerals, magnetite
occurs in feldspars, arranged more or less parallel to the plane of
parting, and in quartz where it occurs as a cloudy matter and in
dendrites. Of other inclusions may be mentioned zircon, apatite,
titanite, and tourmaline (?) in quartz, and very fine glassy particles
in the plagioclases.

“NOTES ON THE REGION ABOUT CAICARA, VENEZUELA — 247

The gneisses, even more than the granites, exhibit overwhelm-
ing evidence of metamorphism, during, as well as since, their
formation. Among the evidences of ‘stress and shearing, may be
mentioned: The wavy extinction in quartz and feldspar grains;
the bending of biotite; the differential bending and anastomosing
of the lamellae of feldspars; cracks and fractures parallel or normal
to the plane of parting in biotite; the slicing of crystals of peg-
matite and microcline; the breaking of crystals of feldspar and
biotite and displacement of the broken parts by miniature fault-
ing; a granulation zone about grains of pegmatite.

A gneissoid texture is given to the rock by the more or less
parallel arrangement of the longer axes of the minerals to the plane
of schistosity of the rock.

The dissolving agency of descending waters is shown by the
schiller structure of some plagioclases, the cloudy appearance of
other feldspars, and the decomposition of some of the magnetite,
biotite, and hornblende. The anamorphic agency of ascending
waters is indicated by secondary growth of quartz, plagioclase,
and biotite; by the cementing of cracks and fissures, and by the
formation of veinlets by segregation from the same mineral or by
infiltration from some other source.

3. THE VEINS AND DIKES IN THE GRANITES AND GNEISSES

The writer profoundly regrets that he. did not have time to
examine more closely the veins and dikes of the cerros about
Caicara, as a more detailed and special study of these veins and
dikes most probably would have brought out different sets, as
indicated by uniformity of strike and dip and of composition,
and might have shown something in relation to the nature and the
succession of the dynamic movements which the gneisses and the
granites, individually or together, have undergone.

While the writer is far from attaching any special significance
to it and deducing any particular law of succession from it, because
of the limited material on hand, it is nevertheless a peculiar fact
that all of the more prominent quartz veins and dikes encountered
have a strike magnetic N.—S., while all the pegmatite veins and
dikes strike E—W. Near the summit of Cerro de Morano a vein

248 T. A. BENDRAT

of fine-grained amphibolitic gneiss, varying in thickness from two
to three feet, strikes N.S. A few feet below the top of Cerro de
los Spiritos a felsite vein about one foot thick extends E.-W. and
stands two feet above the surrounding coarse-grained granite, so
that from a distance it has the appearance of the remnant of a
brick wall. A microscopic investigation showed that its main
constituents are quartz and plagioclase in nearly equal propor-
tions, while some dark-brown and yellow biotite occurs as an
accessory mineral. A microscopical examination of the N.-S.
quartz veins shows that they are made up of very small grains of
quartz with dentated margins in most cases and most intricately
interlocked; of bronze-brown to dark-green amphibole in irregular
patches; occasional tourmaline in radiate aggregates; some garnets,
and some magnetite.

In concluding, the writer wishes to remark that it would be
of great interest to ascertain the geologic and petrographic nature
of other outliers in those waste plains that approach the Orinoco
from the S. and from the E., as well as the character of the rocks
that make up the bulk of the Guiana mountain system, in order
to bring out facts that would bear on the relations of those cerros
to this, most probably, Archaean center.

THE AGE OF THE TYPE EXPOSURES OF THE
LAFAYETTE FORMATION!

EDWARD W. BERRY
Johns Hopkins University, Baltimore

The following brief communication is devoted to showing the
Eocene age of the type-sections of the Lafayette formation in
Lafayette County, Mississippi, and also at certain additional
localities in northern Mississippi and southwestern Tennessee
where fossil plants have been collected by the writer.

The term Lafayette formation has come in late years to be
widely used by American geologists and the volume of literature
devoted to its consideration is by no means inconsiderable.

It is not necessary in the present connection to recite the his-
tory of the study of the deposits which have been referred to the
Lafayette. It will suffice to recall that the name was proposed
by Hilgard? in 1891 for those deposits so elaborately described in
his Geology of Mississippi} as the Orange Sands, and typically
developed in Lafayette County. Chief among the students of the
Lafayette was W J McGee who extended their occurrence from
Mississippi to Pennsylvania on the one hand and as far as Texas
on the other.‘

The writer is not concerned in the present brief note with those
deposits in the various Atlantic and Gulf states which have been
referred to the Lafayette formation by different geologists. In
certain limited areas, however, reliable data have been obtained
which may appropriately be announced in the present connection.
Thus in the vicinity of Columbus, Georgia, materials classed as
Lafayette are Cretaceous in age. Other materials referred to

t Published by permission of the Director of the U.S. Geological Survey.
2 Hilgard, Amer. Geol., VIII (1891), 130.

3 Hilgard, Rept. on Geol. and Agr. of Miss. (1860), 5-46 (the name Orange Sand
was that of Safford, 1856).

4 McGee, U.S. Geol. Surv., t2th Ann. Rept., Part I (1891), 347-521.
240

250 EDWARD W. BERRY

the Lafayette in the vicinity of Glen Allen, Fayette County,
Alabama, should be assigned to the Tuscaloosa. In several sec-
tions across the Cretaceous of northeastern Mississippi in the
latitude of Tupelo and Booneville, the Lafayette cover in all
observed exposures resolves itself into the weathered beds of the
Cretaceous. The same statement is true in the writer’s judgment
of the great cut near Cypress, Tennessee, on the Southern Rail-
way. This whole section was included in the Orange Sand by
Hilgard and figured diagrammatically on p. 16 of his Geology of
Mississippi, though it was subsequently shown that the basal
part was Ripley Cretaceous. The writer visited this exposure
during the past season and failed to see any reason for not includ-
ing it allin the Ripley. Furthermore, at a large number of localities
throughout the Mississippi embayment area, Pleistocene terrace
deposits have been referred to the Lafayette formation.

During ro1o it was the writer’s privilege to spend considerable
time in the collection of fossil plants in Lafayette County, Missis-
sippi, and northward as far as Cairo, Illinois. It might be added
parenthetically that five previous field seasons spent, for the most
part, along the inner margin of the coastal plain from New Jersey
to Mississippi have afforded considerable opportunity for observ-
ing the so-called Lafayette.

It has been commonly supposed for some years back that the
Lafayette formation of Mississippi and western Tennessee was not
a unit, since remains of the so-called eolignitic flora have been
reported from time to time as occurring in it at numerous localities. -
It has been assumed, however, that these plants came from the
Eocene clays beneath overlying Lafayette materials. While at
most of the localities visited during 1910 the Wilcox clays with
leaf impressions are overlain by reddish sands of no considerable
or uniform thickness, this is not always the case, as is well shown
by one of the exposures along the Illinois Central Railroad just
north of Oxford, Miss. The outcrops in these railroad cuts, a
number of views of which, from photographs by the writer, are
here reproduced, were the type-sections of Hilgard’s Orange Sands
and Lafayette. Here as at every other locality where the writer
collected plant fossils in Lafayette and Marshall counties, Missis-

AGE OF EXPOSURES OF LAFAYETTE FORMATION 251

sippi, and in Fayette and Hardeman counties, Tennessee, there is
no unconformity between the Eocene Wilcox leaf beds and the
supposed Lafayette if the latter be restricted to the few upper feet
of weathered sands.

In order that there might be no room for doubt but that the
Oxford exposures furnish the type-sections for the Lafayette, Dr.
McGee has kindly prepared the following letter covering this point,
at the request of Dr. T. Wayland Vaughan, geologist in charge of
the coastal plain investigation for the U.S. Geological Survey:

[Copy]
March 1, 1911

My pear Doctor VAUGHAN: In further reply to your oral inquiry:
On looking up the records, I find it clear that the type locality in Lafayette
County, Mississippi, from which the Lafayette formation received its current
designation, is Oxford, the site of the state institution of learning with which
Dr. Hilgard was long and honorably connected; and that the type-section is
the exposure in the Illinois Central Railway cut at Oxford shown by Dr.
Hilgard in Geology and Agriculture of Mississippi (1860), p. 6, in the drawing
reproduced by me in “The Lafayette Formation’’ (Twelfth Annual Report,
U.S. Geological Survey, Fig. 58, p. 457). This section was in good condition
for examination in 1891, and was re-examined as the type-section by Dr.
Hilgard, the late Dr. J. M. Safford, Dr. Eugene A. Smith, Dr. Joseph A.
Holmes, Professor Lester F. Ward, Mr. Robert T. Hill, and myself, jointly, and
was still in good condition in February, 1910, when re-examined by Dr. E. N.
Lowe, state geologist, and myself, as the type-section cf the formation.

Yours sincerely,
(Signed) W J McGEE

In the exposures at Oxford the deposits are a unit with every
gradation from unweathered materials below to oxidized and
more or less ferruginous sands above. Nowhere in this region is
‘there a line of unconformity or a pebble bed to mark the supposed
time interval extending from the early Eocene to the Pliocene.
The change in color of the materials when marked at all is at
varying levels and is due apparently to the depth to which the
ferric oxide in the sands has been dehydrated. A quotation from
McGee’s longer paper on the Lafayette will make it clear that he
did not recognize any unconformity between the leaf-bearing clays
now ascertained to be Eocene, and the overlying sands. On

pp. 458, 459, he says:

252 EDWARD W. BERRY

Several competent geologists familiar with the Lignitic in Mississippi,
Alabama, Tennessee, and Arkansas are disposed to refer the leaf bearing
clays to that formation on the ground of lithologic resemblance. If this
reference be just, then the thickness of the formation may be less than that
assigned by Hilgard at Oxford and Johnson at Holly Springs, and even the
exposed thickness at La Grange may include an unknown amount of the
protean Lignitic deposits though no demarcation has ever been found.

At one of the Oxford exposures, previously mentioned, the
Eocene clay lens is almost at the surface and overlies “typical

Fic. 1.—Diagram of exposure furnishing fossil leaves in the type area

Lafayette materials.” This section is shown diagrammatically
in Fig. 1, and may be described as follows:

SECTION EAST OF I.C.R.R. } MILE NORTH OF OXFORD STATION

No. 1. Brown loam : : An PIA
2. Rather coarse brown suriined said : : 4— 6 **

3. Lens of gray to white siliceous clay, carrying abundant leak
impressions .__. Reh eee MM eT co GG.
4. Stratified orange cea f A a—- 3 *

5. Lens of gray siliceous clay, with moody oreemed fea impres-
SIOnSHas o- 4 ‘

6. Coarse brown cross- chedded ened ccourated be fermen
indurated bands 1 to 3 inches in thickness. Replaced hori-
zontally by pinkish or grayish buff finer sands . . . 10-12

(a9

Fig. 2 is from a photograph of this outcrop, the fossil plants
having come from near the top of the exposure at the “nose”
just below the small tree shown in the center of the picture. The
clays at this point are siliceous and do not contain an extensive
flora, and the collections consist largely of the abundant remains

Fic. 2.—View showing the plant locality one-half mile north of the depot, Oxford,
Miss.

Fic. 3.—View showing ferruginous cross-bedded sands just north of the plant
locality.

254 EDWARD W. BERRY

of a Panax-like form and a fan palm identical with what Lesque-
reux called Sabal grayana. The latter was originally described
from the Lignitict and the former, while apparently new, is closely
allied to early Tertiary forms from southern Europe. Few forms
abundantly represented may be taken as indicating that the
plants were not drifted into the basin of sedimentation from a

Fic. 4.—View showing the type-section of the Lafayette just south of the depot
at Oxford, Miss.

distance but that they grew in the immediate vicinity and that the
shallow waters of the Mississippi gulf in Wilcox time were not
marine in this latitude. This is also indicated by the impressions of
Unios in this same clay lens. At some of the other plant localities
visited, as for example that at Holly Springs and Early Grove in
Mississippi and at Grand Junction and La Grange in Tennessee,
all of which are specific Lafayette localities of McGee, the fossil
floras are more varied and consist of species of Cercis, Laurus,

* Lesquereux, Proc. Amer. Philos. Soc., XIII (1869), 412, Pl. XIV, Figs. 4-6.

AGE OF EXPOSURES OF LAFAYETTE FORMATION 255

Ceanothus, Banksia, Dryophyllum, Sabal, Ficus, Dalbergia,
Nerium, Terminalia, and perhaps one hundred additional forms,
including even flowers and Acacia-like pods, all unquestionably of
Eocene age and closely paralleling the Eocene floras of southern
Europe. Furthermore these Eocene forms are all of them contained
in beds absolutely inseparable from the surficial more or less

Fic. 5.—View showing the character of the materials referred to the Lafayette,
one mile north of depot, Oxford, Miss.

oxidized sand which a forlorn hope might lead one to retain as
representing the Lafayette.

It must not be supposed that there are no surficial deposits in
this general region. The present communication is merely intended
to show that certain fossiliferous sections including the type-section
of the Lafayette and probably all of the Lafayette in Lafayette
County, Mississippi, are of Wilcox Eocene age. A possible objec-
tion to the foregoing conclusion might be that these floras upon
which it is in part based are really Lafayette floras. This is

256 EDWARD W. BERRY

utterly impossible. In the first place it would mean that the
balance of the leaf-bearing Wilcox is of Lafayette age since the
two have a considerable number of species in common. McGee
seems to have had some premonition that the fossil plants when
studied would not bear out his conclusions since he writes:

The testimony of the plant fossils is of course only suggestive; for not
only is the identification incomplete, but there are thus far no means of
comparing the stages in evolution of plant life in the upper Missouri and
Rocky Mountain regions and the lower Mississippi region respectively; it
can only be said that in the one region the geography was repeatedly revolu-
tionized in such way as greatly to modify climatal conditions, while in the
other the geography has undergone only minor changes of such character as
not to modify climate, so that the flora has undoubtedly persisted in the
remarkable fashion suggested by the present existence of Laramie or Lafay-
ette plants in Louisiana.

This may be dismissed as a specious argument, for it can readily
be shown that no post-Miocene floras of the northern hemisphere
contain the types which are prominent in this flora. On the
other hand the climatic changes have been considerable, even the
Pliocene flora in this area of supposed slight change containing
species no longer present in the region or even in North America.

In the second place the flora is closely allied to European floras
of unquestioned Eocene age, more especially to that described by
Saporta from France, and in its tout ensemble it denotes climatic
conditions very different from those which could possibly have
existed in Lafayette time.

There are high-level gravels in northeastern Mississippi and
in northern Tennessee and beneath the loess along the Mississippi
bottom (“delta”) as well as at various points along the Atlantic
Piedmont border. Whether these are river gravels of various
ages or whether we are dealing with the remnants of a high-level
early Pleistocene sea terrace is not clear, although a combination
of the two is the probable solution.

THE RIPPLES OF THE BEDFORD AND BEREA FORMA-
TIONS OF CENTRAL AND SOUTHERN OHIO,
WITH NOTES ON THE PALEOGEOGRAPHY
OF THAT EPOCH*

JESSE E. HYDE
Columbia University

THE BEDFORD AND BEREA FORMATIONS

The Bedford and Berea formations are respectively the lowest
and second lowest members of the Waverly series of Ohio. They
were formed either at the close of the Devonian or at the beginning
of the Mississippian period. They can be traced continuously
across the state along the outcrop, from the Pennsylvania line
on the northeast to the Ohio River on the south and over broad
areas under cover to the eastward. The Bedford is almost entirely
a shale formation usually about too feet thick; the Berea is a
sandstone roughly from 20 to 150 feet thick.

In northern Ohio, the Bedford is largely an argillaceous shale
with sandstones present locally, the Berea a coarse, feldspathic
sandstone; the two are separated by an erosion plane.?_ In south-
ern Ohio the Bedford consists of interbedded sandstones and shales,
the former sometimes greatly in excess, the Berea of similar sand-
stones with limited quantities of shale. The sandstones in both
are fine grained and of exactly the same type while between the
two there is a transition zone. It is now becoming evident that
the geological history of these beds has been quite different on
opposite sides of the state, although the relation of the succession
in one area to that in the other is not yet known. The Berea of
southern Ohio is only a phase of the Bedford of the same region,
while that of northern Ohio is wholly distinct from the Bedford
and probably from the southern Ohio Berea. However, as a
sandstone formation, it is continuous across the state.

t Published by permission of the State Geologist of Ohio.
2 Charles S. Prosser, manuscript.
257

258 JESSE E. HYDE

In the area under immediate consideration, central and southern
Ohio, the Bedford is from go to too feet thick, the Berea from
5 to 40 feet thick. In Scioto County on the Ohio large amounts
of sandstone are found in the Bedford, but this diminishes to the
northward so that there is much more shale in Pike and Ross
counties, while in Franklin County there is practically no sand-
stone, except in the upper to feet where very thin layers appear
in profusion. In Pike and Ross counties the sandstones are
frequently limy. When present, the sandstones are in beds from
a few inches to two or three feet thick, but the ‘“‘shale’’ beds
intervening between such beds, often several feet thick, are largely
made up of very thin, hard, platy sandstones of which there may
be 12 or 18 in a foot.

Exactly the same type of sandstone is found in the Berea of
central and southern Ohio as in the Bedford, except that the lime
disappears. In fact the Berea is distinguished from the Bedford
of the region almost solely by the rather abrupt diminution in the
amount of ‘“‘shale.”’ These shale beds are found to some extent in
the lower part of the Berea and, just as in the Bedford, they carry
the numerous, thin, platy sandstones. In other words, the litho-
logical change from the Bedford to the*Berea was almost wholly
one of amount and not of kind of material.

THE OCCURRENCE OF THE RIPPLES

Ripples are seldom noted in the lower part of the Bedford.
In southern Ohio they appear rather gradually near the middle,
and throughout the upper half of the Bedford and most of the
Berea they are present, sometimes in astonishing abundance.
The surface of each of the very thin lamellae of sandstone is rip-
pled, as well as of the thicker beds. In central Ohio they appear
first in the thin sandstones at the top of the Bedford, but are
confined almost wholly to the Berea. In central Ohio and as far
south as Pike County, the ripples gradually disappear in the
upper part of the Berea and they may be absent entirely in the
upper 10 or 15 feet, which also may become slightly coarser.

Many localities can be found, especially in Pike County, where
the streams have cut into the Berea grit or the upper part of the

RIPPLES OF THE BEDFORD AND BEREA IN OHIO 259

Bedford, and flow for some distance over a rock floor composed

of the strata of these formations.
descending order, each with a
beautifully rippled upper surface,
and where the stream cuts through
one of the “shaly”’ beds as many
as 12 or 18 may be encountered
in a vertical thickness of one foot,
each ripple-marked. ‘The parallel-
ism of these ripples is most strik-
ingly shown where the gradient is
such that the stream descends
gently across such a series, each of
the surfaces forming the creek bed
for a distance, to be superseded
presently by the next layer lower
down.

REVIEW OF PREVIOUS WORK

E. B. Andrews in 1870 first
noted that the ripple-marks in the
vicinity of Buena Vista trend in
a northwest-southeasterly direc-
tion! The formation in which
they occur is not indicated and
the context suggests that they
are in the ~:city ledge~ of the
Cuyahoga, but they can only be

Bed after bed is exposed in

Fic. 1.—A portion of the upper
part of the Bedford in the D.T. and
ILR.R., cut southeast of Waverly,
showing the many thin platy sand-
stones which largely make up the
shaly portions of the formation. Each
is rippled. Sometimes only the crests
of the ripples are preserved as a series
of lenses. The thicker sandstones are
not present in this outcrop.

in the Bedford and Berea, since ripples do not occur in the other.
Dr. Edward Orton, Sr., next called attention to the constancy
of direction of these ripple-marks in Pike County. In his account
of the geology of Pike County he says ‘‘the surfaces of successive
layers, for many feet in thickness, are often covered with ripple-
marks, all of them holding the general direction of north 53° west,

tGeol. Surv. Ohio, Rept. Progress [in 1869] in Second District, ed. of 1870, p.

68; ed. of 1871, p. 72.

JESSE E. HYDE

260

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eee ea EOIN IONS OF 7 HRS

I
cee !
Ny | SS = f : 5 I
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2.—Outline map of Ohio
Ohio (dotted line across

Fic.
showing area represented in large

map of ripple directions,
general directi

axis in
western part)

ls
Xf

RIPPLES OF THE BEDFORD AND BEREA IN OHIO 261

or south 53° east.”* In a footnote to the last, he states that Mr.
H. W. Overman, the county surveyor, made a careful series of
measurements of these directions. ‘“‘Of twenty-four observations,
fourteen were found south 53° east. Four points showed south
65° east; one south 46° east; one south 57° east. The points
that showed south 65° east overlie the other exposures, and prob-
ably indicate a real change of direction in the wave action.”

THE NATURE OF THE RIPPLES AND THE PERSISTENCY OF THE RIPPLE
DIRECTION

These observations which are given above in full suggested to
the writer that further similar observations over a wider area
might prove of value in the interpretation of the geography of
the Bedford-Berea sea. Accordingly determinations of the direc-
tion of the ripple-marks in both the Bedford and Berea have been
made sufficient practically to cover the whole of the outcrop in
Scioto and Pike counties and most of Ross County, an area about
50 miles in length (from north to south) by 20 in breadth. Obser-
vations at three localities in central Ohio, Lithopolis, Gahanna
(Rocky Fork), and Sunbury (Rattlesnake Creek), show that the
same persistency continues to the northward, a total distance
from the Ohio River of 115 miles.

The results of 149 observations have been merely to confirm
Orton’s observation on the original much smaller area, as to the
general direction of the ripples. However, his statements as to
the extreme persistency of the 53° angle are not borne out, and,
if the area as a whole is considered, no tendency is apparent on
the part of the higher surfaces to carry ripples trending more
nearly east and west, as he seems to have found them. -

At all points where several rippled surfaces are exposed, varia-
tion in direction is found, and not infrequently where one surface is
exposed continuously for some distance, considerable change may
be found in the direction of the ripples which cover it. This, of
course, is to be expected. Not infrequently a range of five or ten
degrees will be found on an outcrop showing possibly only six or
eight surfaces; indeed, as great a range can be found in one ripple

t Geol. Surv. Ohio, Vol. II, Part 1 (1874), 620.

262 JESSE E. HYDE

within a few feet along its length. Just below Denver in Pike
County, two widely variant sets of ripples were observed on
adjacent planes less than an inch apart, one trending N. 28°
W., the other N. 55° W. Such an extreme difference is unusual,
but differences of six or eight degrees between adjacent planes
can be found without effort. The greatest range noted at any
locality is 43°, in the Berea grit below Denver in Pike County.
The widest extremes found in the area from Chillicothe southward
are N. 22° W., and N. 78° W., a range of 56°. The latter has been
recorded several times, especially in the southern part of the area,
but the former is an unusual direction. It was found on one plane
in the Berea north of Clifford, Scioto County, associated with a
number on which N. 60° W. was markedly dominant. In the
central Ohio outcrops the extremes are N. 9° W. (on three super-
imposed planes at Sunbury) and N. 78° W. at Gahanna. This is
the absolute range for the whole region, 69°.

Most of the ripple directions noted in the course of the present
work have been drawn in on the accompanying map. (Fig. 3.)
At some points where a number of directions have been noted,
not all are plotted, but in every case where more than one direc-
tion has been found, the extremes have been drawn in. On the
other hand, at many localities where the ripples persistently
trend in one direction, only one observation is plotted, and at
almost all points where considerable variation is indicated some
one direction lying between the extremes is certain to be dominant,
although not so indicated. Thus the map is really a map showing
extremes of ripple direction, not only areally but vertically. If
the directions were drawn in, in the order of their persistency,
the amount of variation which exists would largely be obscured,
and the unity of the direction would be much more impressively
set forth. As it stands, however, it is sufficient to indicate clearly
that some factor must have controlled the ripple direction in cen-
tral and southern Ohio during the time when the upper part of the
Bedford and Berea were accumulating.

The ripples are entirely (so far as observed) of the oscillation

Observations are all compass readings. The magnetic declination is one degree
or less west of the true north (determined in 1906).

RIPPLES OF THE BEDFORD AND BEREA IN OHIO 263

type, that is, formed by the slight forward-and-back motion of
the water which is caused by the passage of a wave. Not a single
occurrence has been noticed which suggests typical “‘ripple-drift,”’
the type of ripple which is produced by strong currents of water
moving in one direction. The ripple crests are usually from three
to five inches apart and rarely reach six inches. This interval
varies within a few feet on any surface.

Considerable experimental work has been done on the ripple-
marks produced in sand by such waves. Notable is the work by
Forel,t A. R. Hunt,? and G. H. Darwin.3 The work of these men
shows that, when a wave passes over a body of water, the slight
oscillation of the water beneath it can be detected to a considerable
depth below the surface. To what limit it may extend is unknown.
This oscillation sets up small vortices in the water next the bottom,
and in the course of time sand ripples are produced by the action
of these vortices. These sand ripples are produced at right angles
or nearly at right angles to the direction of movement of the wave:
that is, they are approximately parallel in direction to the lateral
extent of the wave. If the waves on a body of water extend in a
northwest-southeast direction (at right angles to the direction of
their movement) the ripples generated by them in the sands of
the bottom would trend, in general, in the same direction. If we
are seeking the factor which controlled the sand ripple directions
in the Waverly, we find it directly in the waves which have pro-
duced them. It then remains to ask how the direction of water-
waves is controlled, and what kept them practically parallel over
a wide area throughout a considerable interval of geological time.

Hunt? has recorded his observations on ripple direction on the
north shore of Torbay which faces the English channel toward
the southeast. A portion of the beach examined was so protected

™ “Tes rides de fond,” Archives des Sciences Physiques et Naturelles Genéve (1863).

This paper has not been seen by the writer but his results are stated, apparently quite
fully, in the paper by Darwin.

“On the Formation of Ripple-Marks,” Proc. Royal Soc. London, XXXIV
(1882), 1-18.

3 “On the Formation of Ripple-Mark in Sand,” Proc. Royal Soc. London, XXXVI
(1883), 18-43.

4 Tbid., 6 and 7.

264 JESSE E. HYDE

by a breakwater as to receive waves from the southwest only,
while farther west along the shore, as the influence of the break-
water became less and less, the waves came from the south and
then from the southeast. The beach was examined after a week
of calm weather on the day following one on which there had been
a slight swell. The sand ripples were found to correspond closely
to the direction from which the waves came. Behind the break-
water their trend was northwest-southeast, parallel to the waves
coming from the southwest, but as the control of the barrier became
less and less to the westward, the ripple directions changed to east
and west and then to northeast-southwest, as the waves came
from the south, and then from the southeast.

These observations show the independence by wave direction
from wind control, the control of wave direction by shore line,
and the dependence of ripple direction directly on wave direction.

The parallelism of waves to coasts is generally known, and
examples could be multiplied from the beaches of the eastern
United States and elsewhere. Since, however, there is no data as
to the direction of the ripples induced by these waves, no other
need be added here.

In discussing the parallelism of the Bedford-Berea ripples with
various persons, it has been suggested that it might indicate the
direction of the prevailing wind. In the present geological period
the direction of the prevailing winds in Ohio is from the westward.
But the actual winds experienced, as a result of the cyclonic con-
trol of weather, are so variable that it is impossible to assume that
the persistency of the Bedford-Berea ripples could be maintained
under similar conditions of cyclonic variation, if those ripples
were controlled direcily by the winds. If they are held to indicate
wind direction, we must postulate a series of winds in Bedford-
Berea time more uniform in direction, even, than the trade winds,
which not infrequently may vary throughout the whole range
of the compass in the course of a year, as shown by almost any
sailing chart of those regions, and always vary through more than
a quadrant of the compass.

On the other hand, granted that the winds initiate the water
waves, as soon as they come within the influence of shallow water

RIPPLES OF THE BEDFORD AND BEREA IN OHIO 265

they are retarded more in the shallower portions, so that by a
process of wave-refraction they are soon brought into a line roughly
parallel with the contour lines of the bottom. And the contour
lines of the bottom, on all gently sloping coasts, are nearly parallel
to the shore line.

The conclusion seems to be warranted that the persistency of
direction of the ripples of the Bedford and Berea indicates the
prevailing direction of the water waves which formed them, and
that this in turn was controlled, either by a shore line or water
so shallow as to bring the waves into adjustment parallel to this
shore line, or, if it was only shallow water control, to the contours
on the sea floor. The shales of the Bedford clearly indicate that
there must have been an open sea to the northeastward. Toward
the southward the sediments become more sandy and on the whole
coarser (the sandstone becomes but slightly coarser but increases
very much in relative amount). From this we conclude that
either a shore line or shoal water lay toward the southward with
decreasing depths of water in that direction sufficient to cause
wave refraction. This shore line or the contour of the bottom
must have been parallel to the ripple direction, that is, it must
have extended in a northwest-southeast direction.

Probably the sea in which these sediments accumulated was
of moderate depth, sufficiently so that sedimentation would be
continuous. ‘The only evidence of occasional currents which were
strong enough to erode locally is found in the middle and upper
part of the Berea in central Ohio where the ripples are much
less numerous. Quite probably it may have been sufficiently
shallow and so well inclosed and protected that currents and
waves of oceanic proportions could not develop.

CHANGE IN RIPPLE DIRECTION IN PASSING FROM NORTH TO SOUTH

A brief survey of the map suggests that the directions along the ©
Ohio River tend more nearly east and west than they do farther
north. The number of directions occurring within each five
degrees has been plotted in four areas. This brings out the fact
that there actually is a swing in the direction of the majority of
the ripples to more nearly east and west in southern Ohio. In

266 JESSE E. HYDE

central Ohio the greatest number trend between N. 50° and 55° W.
In Pike and Ross counties by far the greatest number trend from’
N. 55° to 60° W. In northern Scioto County the maximum
is between N. 60° and 65° W., and along the Ohio River it falls
between N. 65° and 70° W. The significance of this definite and
controlled variation is not apparent at present. The occurrence
is merely noted in passing as suggesting one of the methods of
attack in such a problem which may yield results.

EVIDENCE FROM THE RIPPLE DIRECTION ON THE ATTITUDE OF THE
CINCINNATI AXIS AT THIS TIME

The region of the Cincinnati uplift lies but a few miles to the
westward of the area in which the ripples are mapped. This is
known to have been a region which from the end of the Ordovician
onward tended to maintain a somewhat elevated attitude. Accord-
ing to Schuchert’ it is one of the positive elements of the continent.
That is, it tended to be an island or a region of shallow water
while sedimentation was going on in adjacent territories. The
axis of the Cincinnati uplift trends nearly north and south, slightly
northeast-southwest. With its continuation, the Nashville uplift,
the axial trend of the whole is decidedly more northeasterly.

In seeking a coast line which controlled the ripple direction,
this positive element suggests itself at once. It has been generally
held that there was land in that quarter throughout the Mississip-
pian period and such is indicated on Schuchert’s map of this stage.”
However, by comparing the ripple directions with the present
axis of the uplift, as indicated on the outline map of Ohio (Fig.
2), it can readily be observed that the ripples stand almost at a
right angle to the axis. If it is supposed that the Cincinnati dome
stood high at that time with its axis as at present, it is necessary
to assume that within a few miles, certainly not more than 30, to
the westward, the ripples were sharply bent into parallelism with
this axis. The fact that the ripple direction shows no tendency
whatever (the observations are sufficient on this point) to swing
into such adjustment to the westward is held to be sufficient

t Bull. Geol. Soc. Am., XX (1910), 470.
2Tibid.. Pls.735 79:

RIPPLES OF THE BEDFORD AND BEREA IN OHIO 267

evidence that there was no such control in that direction at that
time.

Futhermore, the axis which lay to the southward and which
did control the ripple directions was directly transverse to the
present Cincinnati axis. Whether or not this axis is to be con-
sidered as the result of the same forces and conditions which
determined the Cincinnati axis, but which were operating in a
different manner during Bedford-Berea time, is a question whose
answer is, perhaps wholly, a matter of personal opinion. The
question is one of some importance in determining the nature of
forces and conditions lying back of such a positive element of
the continent. The case is of especial interest in view of the fact
that, in the Cuyahoga formation which almost directly succeeds the
Berea,’ there is positive evidence of a different nature that the
Cincinnati dome had nearly the axial alignment which it holds
at present for at least 40 miles north of the Ohio River where the
evidence is lost, due to the swinging of the outcrops to the eastward.

In view of the suggestion that the shore line lay to the south-
ward, a word is desirable as to the nature of the Bedford and Berea
formations in that direction. W.C. Morse and A. F. Foerste have
traced them southwestward into Kentucky for 80 miles and show
that the horizon thins rapidly, being reduced at some points to two
or three inches. The sandstones and ripple-marks (directions not
noted) are still in evidence 18 miles south of the Ohio River where
the horizon is only 46 feet thick (as against over too in Ohio).
Beyond this it is much reduced, and consists almost wholly of
argillaceous or calcareous shale, presumably very like the basal
Bedford in Ohio.

The authors mention the possibility that only the basal part
of the Bedford may be represented in this southern extension,
but reject the idea, holding that, even when reduced to two inches,
the horizon is ‘“‘ Bedford-Berea.”’ To the writer, who knows the
area only from their paper, there seem to be many facts which
strongly favor the removal of the Berea and much of the Bedford

tThe Sunbury black shale, 10 to 20 feet thick, intervenes.

2“The Waverly Formations of East Central Kentucky,” Journal of Geology,
XVII, 164-77.

268 JESSE E. HYDE

by erosion, prior to the formation of the next succeeding Sunbury
shale, and their suggestion cannot lightly be laid aside. These
facts are: (1) the presence of a fauna which is found only in the
lowermost two or three feet of the Bedford at Gahanna (Franklin
County), Bainbridge (Ross County), and Piketon (Pike County),
the only localities in central and southern Ohio where the contact
has been observed. In Kentucky a portion of the same fauna
is found when only a fraction of a foot is present. (2) At one
point, Olympian Springs, Bath County, Morse and Foerste note
the following variation in thickness of the ‘“‘Bedford-Berea,”
within two and one-half miles: 123 feet, 52 feet, 2 inches. This
is an extreme case but irregularity in thickness is the rule in the
sections they present. (3) The absence of beds corresponding
to the Berea as soon as the thickness is reduced to less than 70
feet. (It is not apparent that the 74-foot bed they refer to the
Berea in the Elk Lick section, where the total is reduced to 70
feet, is really Berea and not a horizon in the Bedford. Many such
occur.in the Bedford to the northward.)

It is thus uncertain, and perhaps unknowable except by infer-
ence, what the true conditions in Bedford and Berea time were
to the southwestward. If, as seems probable to the writer, only
the basal beds are present, they are not indicative, for the basal
beds throughout southern Ohio are largely shale.

It seems probable that the northwest-southeast axis in Ken-
tucky, which was prominent enough during late Bedford and Berea
time to control the ripple directions, was elevated at the close
of that period so far as to permit the removal of almost the whole
of these deposits. Possibly this uplift did not succeed the forma-
tion of the Berea of southern Ohio, but was contemporaneous
with it, and the extension of the Berea (so called) over southern
Ohio was due to the northward translation of the shallower water
deposits resultant on the uplift. No evidence has been brought
forward bearing directly on this point.

SUMMARY

The Berea of central and southern Ohio is largely a phase of the
Bedford but is readily distinguished by the much greater amount

RIPPLES OF THE BEDFORD AND BEREA IN OHIO 269

of sandstone present. Ripple-marks are abundant in the sand-
stones of the upper half of the Bedford and most of the Berea.
From the Ohio River to the center of the state, a distance of 115
miles and over a width of 20 miles, these ripples are remarkably
persistent in direction, trending northwest-southeast. In central
Ohio the great majority range between N. 40° and N. 55° W. In
passing southward the direction swings gradually to more nearly
east and west, the majority on the Ohio River ranging from N.
60° to 70° W. The absolute range of observations for the whole
region is only 69°. The cause of the progressive variation from
north to south is not apparent.

The general persistency of direction is believed to be due to
parallelism to the shore line of that time, which lay to the south-
ward, and the direction of the ripples is believed to indicate the
approximate trend of this shore line. If such is the case, it is
probable that the Cincinnati axis of that time was not appreciable
as an uplift, or, if active, maintained an attitude quite different
from that holding at present.

The evidence indicates the presence of shoal water, or possibly
a land body, to the south-southwestward the axis of which was
almost normal to the present axis of the Cincinnati uplift. From
the work of Morse and Foerste it seems probable that this axis
became more active later, perhaps closing the Bedford sedimenta-
tions with uplift and erosion. The Berea of southern Ohio may
be the result of the northward pushing of the strand line by this
uplift.

A POSSIBLE LIMITING EFFECT OF GROUND-WATER
UPON EOLIAN EROSION

JOSEPH E. POGUE
U.S. National Museum, Washington

Mr. C. R. Keyes, in a recent article in the Journal of Geology,
discusses the well-known fact that in arid regions erosion proceeds
independently of sea-level and often is effective even below it.
He sets a limit, however, to the depth to which eolian erosion can
extend, in these terms: ‘‘Where the general ground-water level
nearly coincides with that of the plains-surface, deflation can pro-
ceed no farther. This level, which is perfectly independent of
sea-level, can never be very far below it.’”’ In this connection,
it may be of interest to call attention to some suggestions regard-
ing the effect which ground-water, existing under a special condi-
tion, may have upon erosion.

Mr. H. J. L. Beadnell,? in 1909, describes the Kharga Oasis,
which is a depression in the Lybian Plateau of Egypt, worn down >
beneath the general level of the country by the differential effect
of subaerial denudation acting on rock masses of varying hardness
and composition. He states that the oasis was at one time the
bed of an extensive lake, and, from the finding of some fragments
of pottery 7m situ in the base of the lacustrine deposits, concludes
that the lake was contemporaneous with man. In regard to its
origin, he says:

There is an explanation which it is advisable to keep in mind, though it has
never hitherto, as far as I am aware, been advanced as a possible cause of the
formation of lakes. . . . . There is little doubt that the beds which we have
named the ‘‘Surface-Water Sandstone,” and which are now exposed in places on
the floor of the oasis, were originally entirely covered by impervious clays and
contained artesian water under pressure. It is conceivable, therefore, that when

1“ Base Level of Eolian Erosion,” Jour. Geol., XVII (1909), 659-63.

2 An Egyptian Oasis: An Account of the Oasis of Kharga. London, 1909;
abstract, Geol. Mag., VI (1909), 476-78.

270

EFFECT OF GROUND-WATER ON EOLIAN EROSION 271

those beds became exposed at the surface, owing to the removal of the overlying
confining strata, their contained water escaped in such quantities as to have given
rise to a lake of considerable dimensions.

A lake formed in such a manner would certainly put a sudden stop
to the downwearing effects of deflation.

Mr. H. G. Lyons,* on the other hand, in an article written many
years before, states that during the erosion of the Nile Valley the
cutting-back of the escarpment separating the overlying limestones
from the underlying Nubian sandstone encroached upon the
southern limit of the oases, and let loose springs which greatly
increased the rate of erosion. This would appear to be a case
where the presence of ground-water facilitated erosion.

Again, Mr. F. J. Bennett,? in 1908, seems to have the germ of
the same idea, when, discussing the solution-subsidence valleys
and swallow holes within the Hythe Beds area of West Malling
and Maidstone, England, he suggests that the “upward hydro-
static action of water under pressure . . . . is a new contributing
factor in valley formation, and that this in conjunction with
subaerial stream erosion”? formed the valleys and swallow holes
described. This, however, is an application to a region of normal
rainfall and is not strictly 4 propos.

The idea advanced by Mr. Beadnell may be applicable to other
desert regions. It is, at any rate, worth considering, in connection
with Mr. Keyes’s article, as a possible modus operandi of one
limiting effect of ground-water upon wind erosion.

™“On the Stratigraphy and Physiography of the Lybian Desert of Egypt,”
Quari. Jour. Geol. Soc., L (1894), 531-47.

2“*Formation of Valleys in Porous Strata,” Geog. Jour., XXXII (1908), 277-88.

RECENTLY DISCOVERED HOT SPRINGS IN ARKANSAS

A. H. PURDUE
University of Arkansas

Though the hot springs at the city of Hot Springs, Garland
County, Arkansas, probably have been known since the time of
De Soto, the existence of other thermal springs within the state
was not even surmised until February, 1908. At that time, a
man named J. M. Davis, who was then living in or near the town

Fic. 1.—Caddo Gap, from the south

of Caddo Gap, Montgomery County, discovered other thermal
springs issuing from the bed of Caddo Creek in the gap where this
stream cuts through Caddo Mountain. This gap is 31 miles west,
and 10 miles south of Hot Springs.

As the region about the gap is densely settled, as there has
for many years been a small town within a half mile of it, as it is
traversed by a wagon road, and as the stream at usual stage is

272

RECENTLY DISCOVERED HOT SPRINGS IN ARKANSAS 273

easily forded where the springs issue, it seems remarkable that they
did not attract the attention of someone long ago.

Caddo Mountain is one of the numerous east-west ridges that
constitute the Ouachita Mountains of west-central Arkansas.
Its height in the vicinity of the gap is 1,250 feet above sea-level,
and 600 feet above the stream level. As with all the other ridges
of the area, the rocks of this one have been disturbed by folding,
and, in addition to the folding, they have been faulted at the gap;
and like most of the other ridges, including the one from which the
springs of Hot Springs issue, the rocks are of the siliceous type
known as novaculite.

At Caddo Gap, the rocks are on edge, and strike north 80 degrees
east, across the stream. They are here intersected by a thrust
fault, as shown in Fig. 2, with an east-west strike.

Fic. 2.—Showing the geological section and the rock structure at Caddo Gap.
Also, the location of the thermal springs. 5, Stanley shale (Carboniferous); 4.
Arkansas novaculite (age undetermined); 3, Missouri Mountain slate (age undeter-
mined); 2, Bigfork chert (Ordovician); 1, Polk Creek shale (Ordovician); ss, Thermal
springs.

Two springs are known, and their waters rise between the verti-
cal beds of novaculite. Possibly there are others that have not
yet been detected. At the time of discovery, all the water of the
springs issued below the stream level, but the points of emergence
have in part been closed with cement, so that some of the water
now issues from the west bank of the creek. For convenience,
the springs are here spoken of as the north and the south spring.
The surface of the north spring stands about 15 inches and that of
the south spring about to inches above the surface of the creek at
average stage.

The north spring is about 4o feet south of the fault, and the
south one 25 feet farther. The temperatures of the two springs,
on July 2, 1910, as determined with a physician’s thermometer,

274 A. H. PURDUE

were 95 degrees and 96.5 degrees respectively. Doubtless the
temperature is much reduced by the water of the creek and if so
it varies with the seasons. The rock layers between which the
water issues are quite warm to the touch beneath the surface of
the stream. From a rough determination, the flow of each spring
was calculated as 5 gallons per minute. A small bathhouse has
been improvised, into which water from the south spring is pumped
by hand.

A sample of the water from each spring was taken by the writer
and sent to Dr. W. M. Bruce, chemist of the Arkansas Experi-
ment Station at Fayetteville, for analyses. These analyses and
the average analysis of seven of the springs at Hot Springs are
recalculated and the results given in the following table:

Cappo Gap THERMAL SPRINGS AVERAGE oF SEVEN
SPRINGS AT HoT
South Spring North Spring SPRINGS
Constituentstea.se er Parts per 100,000* | Parts per 100,000* | Parts per 100,o00f
S1@ sie ihey tien tears I. 5600 1.8700 4.4450
Hes@7- All @ a seerne ©. 7000 On7200% © dai) ar ed ee
Kas Ae eicea ere ote alec ©. 0000 ©.0000 0.1934
Nias aa Megs sot een orn care 0.7526 0.3340 0.4421
Ca ore kates erent 3.8876 4.1680 4.9370
IY ea eae tiered oe eee 0. 2166 0.4235 0.5621
Hie ee era tesieecnl| miei ce eemectemeee rien he Weill 0 a uleten sete 0.0317
ee are hoa ceed nee 0.4848 0.7138 0.2819
COW aes one ctr eae 6.8265 6.7085 8.8034
SO geraerece seen. aetna ©.I419 ©. 2313 0.7689
otalek pes ieee tee 14.5700 15.1700 20.4055
Tereex€ Opes aster 2.0000 li GOOO: 2 Si lnet re tieet ete
Grains per U.S. gal-
LOT eeates Ree 8.44 8.79 11.88

* Recalculated from analyses by Dr. W. M. Bruce, who gives the constituents as if in (hypothetical)
combination; except SiO: and Al.O;+Fe.0;. In the recalculation, results were carried out to the fourth
place of decimals in order properly to distribute the constituents.

+ Recalculated from data given in Ann. Rep., Geol. Surv. of Ark. (1891), I, 19, where constituents
are hypothetically combined, and are stated in grains per U.S. gallon. ,

The similarity of the analyses is striking, but this would be
expected in water flowing through the same formations, as these
do. It will be noticed, however, that the water of the springs at
Caddo Gap somewhat excels in purity the springs at Hot Springs,
which are themselves very pure.

To the geologist, of course, the interesting thing in connection

RECENTLY DISCOVERED HOT SPRINGS IN ARKANSAS 275

with these springs, as with the longer-known ones at Hot Springs,
is the possible source of the heat. Is this due to (1) chemical
reactions within the rocks through which the water flows, or (2)
accumulated heat from friction, or (3) the presence of hot igneous
rocks beneath the surface, or (4) the breaking down or other
action of radium along the underground course of the water ?
The unusual purity of the water seems conclusive evidence
against the first hypothesis. Granted that heat from friction
can be so accumulated as to bring the rocks to a high temperature,
there is no evidence of recent crustal movement within the region
where the springs occur. ‘The location of the springs is doubtless
due in large measure to the fault, but this probably was formed at
the time of the folding, and if there ever was any localized heat
accompanying the crustal movements, it would be expected to
have been dispersed long ago. Dr. J. C. Branner, many years
ago, stated that the temperature of the waters at Hot Springs
is probably due to their coming in contact with masses of hot
rocks.t In support of this, there are outcropping igneous dykes
in and near the city of Hot Springs, and igneous areas of some
extent only a few miles distant. While there are no known igneous
rocks in the immediate vicinity of Caddo Gap, there are small
outcrops in the vicinity of Crystal Springs 18 miles to the north-
east, and a small igneous area near the town of Murfreesboro, 22
miles to the south. All these igneous outcrops are of Cretaceous
or post-Cretaceous age. So it seems not out of the possibilities
that the temperature of the water at Caddo Gap is due to its
flowing over hot igneous rocks. Whether or not the radium
hypothesis has any value probably could be determined by testing
the water for unusual radio-activity. This has not been done.

t Ann. Rep., Geol. Surv. of Ark. (1891), I, to.

REVIEWS

The Ore Deposits of New Mexico. By WALDEMAR LINDGREN,
Louis C. GRATON, AND CHARLES H. Gorpon. Professional
Paper 68, U.S. Geological Survey, toro. Pp. 361:

This paper treats a subject about which most geologists have known
comparatively little, and of which most of us are eager to learn.
Although some of the mining districts were worked by the Spaniards
long before the United States became a mining nation, the geology and
ore deposits of the state are less well known, perhaps, than those of
any other portion of the country. During the past decade several
papers treating the deposits of large areas have appeared, and these,
the reviewer believes, have contributed fully as much to the science of
economic geology as the more intensive studies of small areas. The
reconnaissance method of study and treatment gives a perspective which
detailed work of small and more or less isolated mining districts could
never do. This paper is the most comprehensive and in its scientific
aspects should be the most useful of its class. The deposits are so
varied and their genesis so clearly discussed that the student of ore
deposits will find the paper to possess the essentials of a textbook of
mining geology.

Pre-Cambrian rocks do not occupy large areas in New Mexico;
the largest masses are found in the north and constitute the southern
extension of the Sangre de Cristo Range of Colorado. This belt ends
some 20 miles south of Santa Fé. Several other, smaller areas of pre-
Cambrian rocks are described. The pre-Cambrian rocks consist of
quartzites, mica schists of clastic origin, and some limestones. These
are intruded by normal granite, which in turn has been intruded by
masses and dikes of dioritic rocks. The latter are at some places cut by
pegmatite dikes and by a later granite. Schistosity in varying degrees
has been produced in both the sedimentary and the igneous rocks.
At some places the granite breaks through or contains remnants of older
greenstone tuffs, amphiboles, and rhyolites. The pre-Cambrian sedi-
mentaries probably correspond in age to those imbedded in red granite
in various places in Colorado. Perhaps they should be correlated also
with the quartzitic Pinal schists of southeastern Arizona.

The pre-Cambrian history, one of sedimentation, mountain build-
ing, and igneous intrusion, was followed by long-continued erosion,

276

REVIEWS 277

which exposed the ancient cores. At the base of the Paleozoic is pro-
nounced unconformity. During Cambrian times a land mass probably
occupied the northern portion of the state. South of this, fossiliferous
Cambrian beds rest upon the ancient complex. The sea shore moved
northward during the Paleozoic, and the Ordovician, Silurian, and
Carboniferous beds overlap the Cambrian, and extend farther north.
' In the northern part of the state the Upper Carboniferous rests directly
upon the pre-Cambrian, and these conditions continue as far south as
Socorro. The Cambrian consists of quartzite, shales, and limestones;
the Ordovician is predominantly of limestone; the Silurian of lime-
stone and quartzite.

The fossiliferous Devonian, represented in the western part of the
state, is a thin formation of clay shale, calcareous in the upper portion.
At some places it is believed there is an unconformity of erosion between
the Ordovician limestone and the Devonian, but at many places they
are conformable.

The Mississippian is recognized at several places south of latitude
34°. The Pennsylvanian is deposited with considerable thickness over
the whole state, reaching a maximum between Santa Fé and Las Vegas.
As far south as Socorro, it consists of sandstone and shales in repeated
alternation with limestone beds. Farther south the pure limestone
prevails and the total thickness appears to diminish. All indicates
near shore conditions in the northern part of the state. The upper
Carboniferous is divisible into two groups, the upper one of which is of
the Carboniferous ‘Red Beds.”’ Unconformities of erosion mark both
the top and bottom of the group. Triassic ‘“‘Red Beds” are unknown
in the southern part of the state, but have been described in the Sierra
Nacimiento.

The Cretaceous rests upon the eroded “Red Beds,”’ the Carboniferous,
and the pre-Cambrian. This series consists of pliable shales which
once extended over the whole territory with greater continuity than
any other formation except perhaps the Early Pennsylvanian.

The Tertiary was marked by igneous activity, mountain making
and ore deposition. First, manganitic magmas were thrust out as
laccolithic masses beneath the pliable, tough Cretaceous sediments.
Marine conditions ceased. Lake basins developed, at least in northern
New Mexico. Mountain building accompanied and succeeded intrusion.
These forces were active mainly in the belt extending southwestward—
the extension of the Rocky Mountain region. The pre-Cambrian core
to the north was forced up by faulting or by warping and faulting.

278 REVIEWS

Southward the sediments were broken into faulted monoclines—the
typical Great Basin structure. Erosion was active in shaping the moun-
tain ranges, especially in the southwest. A second epoch of igneous
activity, distinctly separate from the earlier epochs of intrusion, began,
probably in Middle Tertiary, as in Nevada, Colorado, Utah, and in
general throughout the central West, and andesites and rhyolites, in
places 2,000 feet thick, were extravasated upon beveled sedimentaries.
A large Miocene lake covered the upper Rio Grande Valley, in part at
least. In this, the Santa Fé marl was deposited. Near the close of
the Tertiary, basalts covered this marl, and the eroded older sediments
and igneous rocks.

These eruptions continued during Quaternary times. In early
Quaternary, land deposits of coarse gravels filled some of the structural
troughs to a depth of 1,000 feet. Basalt was poured over these gravels
and smaller flows, perhaps only a few hundred years ago, were extrava-
sated at several places.

The highly acidic potash-rich granites, products of the pre-Cam-
brian igneous period, differ greatly from the Tertiary monzonites, quartz
monzonites and their lava equivalents, and it is concluded that these
two series could not have been derived from a common magma. It is
suggested, however, that the Tertiary rocks were derived from the
same source and that toward the last a differentiation took place in a
magma basin the products of which were basalts and rhyolites.

The mines of the state, it is estimated, have produced some 35,000,-
ooo ounces silver, and $30,000,000 gold, besides considerable lead,
copper, and zinc. Like the area of maximum of orogenic activity,
fissuring and igneous intrusion, the deposits extend southwestward,
through the state, forming a broad belt about 450 miles long, in which
eighty-one mining districts or camps are located. Many types of
deposits are represented, among them copper and iron ores in sedimentary
beds, fissure veins, mineralized shear zones, lenticular veins in gneiss,
replacement veins in limestone, irregular replacement deposits in lime-
stone, contact metamorphic deposits and gold placers. At least three
epochs of mineralization are represented: (1) Pre-Cambrian, (2) Early
Tertiary, (3) Middle and Late Tertiary. There are also, in the “Red
Beds”? (Carboniferous and later), deposits which are not related to
igneous activities and which were formed presumably by cold solutions,
in post-Carboniferous times.

The pre-Cambrian deposits are represented in ten districts. Three
types have been recognized, quartz-filled fissures, usually of the lenticu-

REVIEWS 279

lar type; shear zones filled with quartz stringers; disseminations of
sulphides in amphibole schists. They are in greenstone, granite, gneiss,
or amphibolite. Some of these deposits are accompanied by sericiti-
zation and the development of horny silicates in the wall rock. Some
have been subjected to the stresses of dynamic metamorphism and show
the effect of pressure in lenticular development of quartz and in the
development of minerals like biotite. The values are gold, silver, and
copper. Minerals represented in these deposits are quartz, calcite,
siderite, flourite, tourmaline, biotite, epidote, garnet, chlorite, specu-
larite, pyrite, pyrrhotite, chalcopyrite, galena, zinc blend, molybdenite,
tetrahedrite, bornite, and chalcocite. It is suggested that these ores
are genetically related to the granite magma. The pre-Cambrian
deposits are not extensively developed.

Contact metamorphic deposits are developed where the early Ter-
tiary intrusives, consisting of monzonites, quartz monzonite, grano-
diorites or their porphyries, cut through limestone or calcareous shale.
Metamorphism is not excessive and rarely extends more than a few
hundred feet in a horizontal distance. Mineralization usually accom-
panies metamorphism. Copper, as chalcopyrite, is most common in
the contact metamorphic deposits, but is usually accompanied by zinc
blend. Magnetite is locally developed. With two exceptions, gold and
silver are present as traces only. Galena is generally subordinate;
pyrrhotite is not common. Other minerals are quartz, calcite, garnet,
epidote, wollastonite, tremolite, specularite, magnetite, pyrite, molyb-
denite. Some of these deposits are important. Indicating a transi-
tion between contact metamorphic deposits and fissure veins formed
by magmatic solutions under conditions of less temperature and pres-
sure, there are fissure veins in limestone, the walls of which are in part
converted to garnet and other heavy silicates. The magmatic solutions
causing contact metamorphism added silica and the metals to the
rocks intruded.

Certain veins, not replacements in limestone, are in close genetic
relation to the same early Tertiary intermediate porphyries, which
locally produced contact metamorphic mineralization. Perhaps $20,-
000,000 gold has been derived from these veins, which are believed to
be of deep-seated origin. In a few of these veins silver is the most
important metal. Quartz, pyrite, and gold are almost always present;
barite is exceptional. Tourmaline, specularite, pyrrhotite, magnetite,
flourite, molybdenite, have been noted. Other minerals are calcite,
dolomite, chalcopyrite, galena, zinc blend. Wall-rock alterations are

280 REVIEWS

sericitization, carbonatization, silicification, and pyritization; hydro-
thermal alterations are less extensive than near the vein deposits of
the Middle Tertiary age. At Sylvanite, orthoclase (not adularia) is found
in small veins more or less closely related to pegmatites, but which are
notwithstanding far from the normal pegmatite.

The Santa Rita (Chino) and Burro Mountain deposits also were
probably formed in the first concentration at the time of the intrusion
of the early Tertiary porphyries. These disseminated copper ores are
greatly concentrated by oxidizing surface waters and resemble in many
respects the “‘copper porphyries”’ of Arizona, Utah, and Nevada.

Replacement deposits in limestone, not contact metamorphic deposits,
form an important group which is likewise in close genetic relation to
the early Tertiary intrusions. At Lake Valley the eroded ore deposits
are covered by andesite. Strongly indicating deposition by ascending
magmatic solutions, these deposits have been found in eight of the dis-
tricts below beds of shale. In six other districts they are fissure veins.
Silver is generally the most important metal; lead is almost always
present; gold is absent, barite is rare.

The gangue is siliceous, with one or more carbonates. Other
minerals are fluorite, wulfenite, vanadite, zinc blend, pyrite, chalcopy-
rite, argentite, cerargyrite, silver, limonite, and pyrolusite. No heavy
silicates are found in the limestone along these veins, but silica or jas-
peroid has been developed.

Veins of gold and silver ores connected with volcanic rocks of Middle
Tertiary or later age are developed in ten mining districts. They are
contained in rhyolites, its tuffs and breccias, or in andesites, which have
latitic transitions. Some of these deposits are older than early Quater-
nary basalts. Base metals and sulphides are not prominent in these
veins, lead and zinc are rare, though copper is present in considerable
amounts in several districts. The gangue is quartz, which may be
accompanied by calcite, fluorite, and barite. Adularia is present in
two districts. Pyrite and chalcopyrite are common; bornite is
probably primary. Other minerals are zinc blend, galena, chalcocite,
telluride, tetrahedrite, cerargyrite, etc. Hydrothermal alteration is wide-
spread. These veins are believed to have been deposited by hot waters
very near the present surface at the time of deposition. Possibly the
waters, such as those which have been analyzed from hot springs at
Ojo Caliente, are solutions of the same genesis and character. The
discussion of the relation of the deposits to waters of this character is
an exceedingly suggestive and valuable section of the paper.

REVIEWS 281

There are certain lead and copper veins of doubtful affiliation which
do not appear to belong to any of the groups described and which seem
to have no genetic relation to igneous rocks. ‘They are, so far as devel-
oped, of small importance.

The copper deposits in sandstone, which, in part at least, replace
carbonaceous material and which appear to have no direct connection
with igneous rocks, form a relatively unimportant, but an exceedingly
interesting group. These ores are mainly in the “Red Beds.” The
minerals are chalcocite, bornite, chalcopyrite, pyrite, malachite, azurite,
silica, barite, and gypsum. Frequently these deposits replace coal.
Some ores carry a few ounces of silver to the ton of chalcocite.

It is believed that the metals known to have been present in pre-
Cambrian areas were leached out of these as sulphates, and rede-
posited in sediments that collected in inland lakes or seas. In part
they were deposited as the solid detrital sulphides. When surface
waters leached such beds, copper was dissolved. The waters of the
Red Beds are known to be rich in chlorides and sulphates. From the
organic matter in the beds, hydrogen sulphide would be added, and
this would readily precipitate copper sulphide.

Pages 82 to 348 contain detailed descriptions of the many mining
districts. WHE:

Syllabus of a Course of Lectures on Economic Geology. By JOHN
C. BranNER. Published by Stanford University. 3d ed.,
LOLs Pp: 502.

This syllabus is intended for the use of students in college and after-
ward. The method of treatment of the various subjects is mainly
by outlines, which are to be expanded by notes from lectures, readings,
and observation, and written out on blank pages opposite the outlines.
Numerous text figures and cross-sections of mines add greatly to the
value of the book. The references are full, well chosen, and up to date.

Work. is:

Descriptive Mineralogy, with Especial Reference to the Occurrences
and Uses of Minerals. By Epwarp Henry Kraus. Ann
Arbor, Mich.: George Wahr, roto.

The book contains 334 pages of text and about the same number of
blank pages for students’ notes. It is designed primarily for the stu-
dent of general mineralogy, with little reference to microscopical optics.

282 REVIEWS

The systematic treatment of crystallography which the author pub-
lished several years ago is not incorporated in the Mineralogy. The
treatment and the lists of occurrences appear to be comprehensive.
As in most textbooks in mineralogy, the references to sources of infor-
mation relating to occurrences are inadequate. Such references,
although adding greatly to its bulk, would vastly increase the useful-
ness of a textbook on mineralogy. A valuable feature is a group of
tables listing separately the minerals containing each element.

The Pleistocene Deposits in Warren County, Iowa. By JOHN
LITTLEFIELD Tritton. Chicago: The University of Chicago
Press, tore) bp. 42+5 nes. .7-

As Warren County lies just south of Des Moines beyond the reach
of the later ice invasions, the chief Pleistocene features of this region
are the sub-Aftonian and Kansan till sheets, the interglacial Aftonian
sands and gravels, and the post-Kansan loessial and other deposits.

The most serious problem is found in differentiating the sub-Aftonian

and Kansan tills, especially since the intervening Aftonian horizon-

marker sometimes becomes so scant or obscure as to afford little help
in separating the two tills. Though both till sheets were deposited by

‘glaciers from the Keewatin gathering-ground, certain minor differences

are cited by the author as distinguishing them. Large pebbles and

bowlders are said to be more common in the Kansan than in the sub-

Aftonian in the region under study. Among the stony constituents

the author notes red quartzite as characteristic of the Kansan but not

of the Aftonian and sub-Aftonian, a view supported by a series of pebble
classifications made in the typical Aftonian region by the reviewer.

The author assigns much greater thickness to the sub-Aftonian than
to the Kansan in the region under study and attributes much of the
present topography to drainage lines cut in this older drift during the

Aftonian interglacial period, believing that, while the later Kansan

invasion has partially masked this Aftonian topography by concealing

some of the minor valleys, it has not obliterated the larger ones.

Re aac:

IPELGROLOGICAL ABSTRACTS AND REVIEWS

Epitep By ALBERT JOHANNSEN

KOENIGSBERGER, JOH. FErlduterungen zur geologischen und mine-
ralogischen Karte des ostlichen Aaremassivs von Disentis bis
zum Spannort. Freiburg i. B. und Leipzig: Speyer & Kaer-
ner, 1910. Pp. 63; figs. 8; colored geological map in pocket.

This work is a geological description ot a small portion of the Alps,
12265 km. in extent, between Disentis and Spannort, and just north
of St. Gotthard. It*’is mapped on a scale of 1 cm. to 500 m., on one of
the beautiful maps of the Swiss Topographic Bureau in Berne.

The author tentatively submits the following sequence:

1. Deposition of pre-Carboniferous sediments. These were much
altered by the later intrusives and are now chiefly sericite gneiss.

2. Intrusions of diorite, diorite porphyrite, diabase, and gabbro-
peridotite into Silurian and Devonian rocks. The intrusives are almost
entirely altered to amphibolites but the original rocks in most cases
can be determined. The diorites are accompanied by differentiation
zones of diorite-aplite.

3. Intrusions of gneiss, probably originally granite, into upper-
Devonian rocks, and forming a low-arched laccolith. By this intrusion
the former eruptives and the sediments were metamorphosed into
crystalline schists.

4. Intrusions of syenite, followed by biotite and hornblende granite
(Piz Ner), of middle or upper Carboniferous age.

5. Intrusion of the Aar granite at the contact a beneath the
previously intruded syenite. In places fragments of the latter are
inclosed in the former. Contemporaneously with the intrusion came
the Carboniferous folding, seen in the Wendeljoch.

6. The Jura-Trias folding and thrust faulting of the Alps followed
next and produced further metamorphism. Nowhere are there exposed.
in the Aar massif any contemporaneous intrusives.

The rocks are briefly described, numerous analyses are given, and
the contact effects are shown. The mineral localities are described,
seven excursions are outlined, and complete literature references are
given.

ALBERT JOHANNSEN
283

284 PETROLOGICAL ABSTRACTS AND REVIEWS

FARRINGTON, OLIVER CumMMINGS. Meteorite Studies, III. Publi-
cation No. 145, Geological Series, Vol. III, No. 8. Field
Museum of Natural History, Chicago, 1g1o.

The publication includes: Description of a chondritic meteorite
which fell near Leighton, Ala., on January 12, 1907; description of a
large iron meteorite found at Quinn Canyon, Nev., in 1908; a collection
of analyses of taenite; a tabulation of the well-authenticated times
of fall of meteorites since 1800, compared for years, months, days, and
hours of the day; and a list of the meteorites of the United States,

arranged by states.
EK. R: Liroyp

RosensBuscH, H. Elemente der Gesteinslehre. Third revised edi-
tion with 692 pp., 107 figures, and 2 plates. Stuttgart, 1910.

The appearance of a new edition of this standard textbook is a matter
of more than ordinary interest since it represents in briefer form the
results of the petrographical investigations of the last decade as sum-
marized in the fourth edition of Rosenbusch’s Massige Gesteine. The
fact that the larger and smaller works follow the same general analysis
makes the latter especially satisfactory as a textbook for advanced
students who can use it.

The new edition has been thoroughly revised and, where necessary,
enlarged by the incorporation of new material. The amount of such
additional material is much less than might be inferred by an increase
of nearly 150 pages which is due in a measure to the resetting of the work.
Certain changes in classification, the firmer drawing of the systematic
lines, an improvement in proportion (due to the fuller treatment of for-
merly neglected features), and the introduction of additional chemical
data are the chief changes noted. There still remain, however, several
changes which might be made to increase the logical coherence of the
systematic treatment and the completeness of the chemical discussion.

The book, as in former editions, consists of three parts, dealing
respectively with the eruptive (70 per cent), sedimentary (13 per cent),
and metamorphic (17 per cent) rocks, preceded by an introduction.

The “introduction” remains practically unchanged except for the
substitution of the new average for the composition of rocks obtained
by Clarke and a brief discussion of the cone-in-cone structure.

Part I, “‘The Eruptive Rocks,” following the earlier analysis, con-
siders them from the viewpoint of their substance, geological occurrence,

PETROLOGICAL ABSTRACTS AND REVIEWS 285

texture, age, metamorphism, and classification. Three additions of
moment are noted. These are discussions of (1) gases, based principally
on the work of Gautier without reference to that of R. T. Chamberlin;
(2) the relation of size of grain to the temperature in a cooling intrusive
mass, based on Professor Lane’s paper; (3) applicability of the phase
rule to the complex hydrous and gaseous solutions of more or less dis-
sociated material of the magma which is not an arbitrary mixture but
such that when computed water free contains 184 molecules.

The systematic description of the igneous rocks divides them into
three major groups—deep-seated, dike, and effusive—as formerly. The
groups, in turn, are divided into 1o families, three subgroups, and 14
families respectively. Each family is described with respect to its
mineral and chemical composition, texture, subdivision, geological
occurrence, and distribution.

The discussion of deep-seated rocks shows careful revision and the
incorporation of many of the results of the recent investigations.
The systematic treatment is conspicuously modified by placing the dis-
cussion of the Peridotites last and by the expansion of the chapter on
Tjolite and Missourite into two chapters entitled “‘Missourite and
Fergusite”’ and “‘Tjolite and Bekinkinite.’’ Less conspicuously there is
introduced the far more fundamental conception of the division of the
deep-seated rocks into three great series by the elevation of the Charnock-
ite-Maugerite-Anorthosite series to equal rank with the better known
alkali and alkali-lime series. The new series is characterized as follows:

Charnockite-Anorthosite Series—The rock series based upon gradations
in composition and association in the field passing from Granite through
Syenite and Diorite to Gabbro—the lime-alkali series—and that from alkali
granite through alkali syenites to Essexites, the alkali analogue of the gabbro—
the alkali series—have been well recognized. There have, however, in these
series been certain members lacking, e.g., the alkali analogue of the Diorite
and the lime-alkali analogue of the Nephelite syenite.

Each of the series has its own areas of occurrence and the different members
of a series are usually intimately related in occurrence while members of the
alkali series never occur in regions of lime-alkali rocks.

We find now among the Plutonic rocks, a type whose mineral composition
is of the same sort as the gabbro—the anorthorite and labrador fels—which,
notwithstanding its chemical character and association, varies throughout
from the gabbro. This anorthorite type we find in association with the
hypersthene granite or charnockite, and here, moreover, the silica-rich char-
nockite is connected by a number of intermediates with the silica-poor anortho-
sites, so that we may speak of a charnockite-anorthosite series which even has
peridotite or pyroxenic end members. ... .

The number of occurrences of rocks of the charnockite series is, on the

286 PETROLOGICAL ABSTRACTS AND REVIEWS

whole, not as great as those of the other two series and especially the inter-
mediate members between the charnockite and the anorthosite are as yet but
little studied.

The series includes charnockite, maugerite, anorthosite, and kyschtymite,
and is represented in Canada, Norway, Russia, Saxony, and the type locality
of Madras described by Holland.

The analyses show with a rise in silica a decrease in anorthite and, when
this is over 56 per cent, the content of the alkalies, producing microperthites,
rises rapidly at the cost of the lime-soda feldspars until the granitic type of
the series is reached.

The uncertain touch in handling this new series is striking evidence
of the evils of combining the elements of genesis and composition in a
systematic presentation of rocks. Either the integrity of the series
rests upon the chemical similitude of its members or in their genetic
association. It cannot rest on both as of equal supporting value. From
the treatment of this new series by Rosenbusch it is impossible to credit
him with a clear concept without charging him with serious defects in
revision. The series is introduced incidentally (p. 182) without any
forecasting of its existence in the general discussion or in that of the
granites where a typical member of the new series (Hypersthene granite
from Birkem) is cited as a member of the alkali-lime granites, at least by
implication. Moreover, charnockite itself is described briefly (p. 94)
without reference to the new series, while the index to the volume itself
shows no reference to its discussion on p. 182. That it is possible to
erect a new series may be seen from a study of Osann’s analysis, since
rhyolite, micatrachyte, dacite, amphibole-andesite, aplite, granite,
and alaskite show the chemical characteristics assigned to the series,
viz., relatively high alumina, lime, and the alkalis, low iron, magnesia,
and varying silica. :

The discussion of the Essexites, the Shonkinites, and other “basic
alkali”? deep-seated rocks has been entirely rewritten and expanded by
embodying the results of the studies of Hibsch in Bohemia, Lacroix in
Madagascar, and others in different areas.

The chemical discussion at the end of the chapter on the deep-seated
rocks is enriched by the graphic representation of the analyses according
to the scheme proposed by Osann and by a short tentative discussion of
the molecular character of the magmas.

The discussion of the dzke rocks is little changed ‘on that of earlier
editions. A slight modification in terminology from granite porphyry
to granito-porphyritic is noted at the beginning but not consistently
followed, and the introduction of granito-porphyritic rocks equal to the
alkaline and basic alkaline rocks has been made to improve the symmetry

PETROLOGICAL ABSTRACTS AND .REVIEWS 287

of the discussion. The treatment of the eleolite-porphyries has been
rewritten and a section describing the monzonite and _ shonkinite-
porphyries has been added. The fine-grained rocks are divided as
formerly into aplitic and lamprophyric series, the former subdivided
on the basis of habit, the latter on the geological association and ferro-
magnesian constituents. Much of this description has been rewritten.
The additional section on the camptonitic, monchiquitic, and alnoitic
rocks emphasizes their genetic and geological association with the deep-
seated rocks of the alkali series and this relationship is accentuated
by the introduction of a number of analyses and an Osann diagram.

The discussion of the effusive rocks has largely been rewritten with
a marked increase in the chemical descriptions which are supplemented
by the introduction of many new analyses. The chief changes of view-
point occur in the expansion and elaborated classification of the alkali
rocks and in the addition of a lamprophyric group of effusive rocks
analogous to those distinguished among the dike rocks. The kerato-
phyres are now classed with the porphyries of the lime-alkali series
because of their geological association, although it is recognized that
by mineralogical and chemical composition they are often practically
identical with rocks of the alkali series.

The section on the trachyandesites is entirely rewritten and the line
of separation between them and the normal dacites and andesites is
emphasized by the introduction of numerous analyses and an Osann
diagram. The treatment of the basalts and melaphyres remains with
little modification, the author still holding to the distinction of the 3
types on the basis of age, although the citation of examples, e.g., the
Mesozoic diabases of the United States, is manifestly contrary to the basis
of classification adopted. The correlation of the trachydolerites as the
effusive form of the essexite-magma is no longer maintained, the view
being expressed that their systematic position must be postponed pending
the accumulation of additional information.

The lamprophyric effusive rocks are characterized by their low con-
tent of alumina and the almost constant predominance of magnesia
over lime. The erection of this new division is based upon the concep-
tion that the surface equivalents of the more acid rocks are really more
aplitic in their composition and that one would naturally expect to find
analogous lamprophyric equivalents as well. To this division are
assigned the verite, fortunite, and jumillites of Osann, the orendite-
madupite group (and Prowersite) of Cross, the euktolite, coppaelite,
absarokite, selagite, and sanukite.

Part II, devoted to the ‘Sedimentary Rocks,” remains practically

288 PETROLOGICAL ABSTRACTS AND REVIEWS

unchanged beyond minor additions to bring the work up to date. The
treatment of the carbonate rocks is somewhat expanded by a discussion
of the marls, and the origin of odlites, and the origin of dolomites. The
origin of the odlitic iron ores is also discussed in an additional section.
The changes in organic matter by which coal and oil are formed are
classified in accordance with Potonié’s recent paper.

Part III. The third part, dealing with the “Crystalline Schists,”’
has been thoroughly revised and brought down to date without any
serious modification. Greater emphasis is laid on the chemical composi-
tion as an indication of the character of the original rock and here and
there the discussion is an application of physical-chemical conclusions
to the interpretation of the phenomena. Reference is made to the
schistosity developed by crystallization under pressure as described
by Riecke and the terminology is modified by the introduction of the
terms proposed by Becke. In the descriptive portion no change is
made in the systematic treatment, beyond the introduction of a few
new names, such as the myrmekite of Sederholm, the astochite-gneiss of
Belowsky, and the sagvaudite of Pettersen.

While the book as a whole is probably the best elementary textbook
in descriptive petrography because of the clear style and comprehensive
treatment of the subjects, it must be regarded as falling short of the
ideal in the minds of all who find occasion to criticize the continental
viewpoint, which has in large measure been developed through the
writings and teachings of Rosenbusch. The criticisms against the
validity of the dike rocks and the Kern theory are too well known to
need restatement. There are, however, numerous inconsistencies in
the systematic carrying-out of the underlying views which should be
eliminated. For example, the element of age is discarded in the general
discussion but frequently appears in the definitions or descriptions
of the various rocks. There is likewise ground for criticism in the com-
bined use of geological and petrographical criteria in classification which
leads to the separating of rock like the keratophyres from the alkali
rocks from which they are admittedly indistinguishable in chemical
and mineralogical composition and in texture. A third criticism in
systematic treatment is that already referred to in the handling of the
charnockite and anorthosite series and the relative disregard of the
silica content in the chemical discussion by the use of the Osann diagrams.
It is a subject for regret that this excellent textbook cannot be trans-
lated and still more that there is no equally satisfactory work by an
American author.

Epwarp B. MATHEWS

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VOLUME XIX NUMBER 4

THE

JOURNAL orf GEOLOGY

A SEMI- ELS

EDITED By

THOMAS C. CHAMBERLIN AND ROLLIN D: SALISBURY
With the Active Collaboration of

SAMUEL W. WILLISTON ALBERT JOHANNSEN WILLIAM H. EMMONS
Vertebrate Paleontology Petrology Economic Geology

STUART WELLER WALTER W. ATWOOD ROLLIN T. CHAMBERLIN
Invertebrate Paleontology Physiography Dynamic Geology

ASSOCIATE EDITORS

CHARLES BARROIS, France JOSEPH P.IDDINGS, Washington, D.C,

ALBRECHT PENCK, Germany JOHN C. BRANNER, Stanford University i

HANS REUSCH, Norway RICHARD A. F. PENROSE, Jr., Philadelphia, Pa.
_GERARD DEGEER, Sweden WILLIAM B. CLARK, Johns Hopkins University
ORVILLE A. DERBY, Brazil WILLIAM H. HOBBS, University of Michigan

T. W. EDGEWORTH DAVID, Australia FRANK D. ADAMS, McGill University

BAILEY WILLIS, Argentine Republic CHARLES K. LEITH, University of Wisconsin

: MAY-JUNE, 1911

CONTENTS

MAGMATIC {DIFFERENTIATION IN HAWAII ast pon > -- Recrnatp A. DaAty 289
PETROGRAPHIC TERMS FOR FIELD USE - - - - - - - - - ALBERT JOHANNSEN 317
THE EVOLUTION OF LIMESTONE AND DOLOMITE. I- - - EDWARD STEIDTMANN 323

THE,RECURRENCE OF TROPIDOLEPTUS CARINATUS IN THE CHEMUNG FAUNA
FE rg AN Rae GND seal rn KS Sm talline ny OO oleae aoe etn ci eM IK ENDER oH 6
FURTHER: DATA ON THE STRATIGRAPHIC POSITION OF THE LANCE FORMA~
LAO IN Wet 4 C11 VA GR ON 2 sya yl a DSi) Paes ihe ea att teri tna 3 Sr cata heh Elen KNOWLTON 368
Peek NCLAL BOW LDU IRS oes cui, hol une. sa So eee GEORGE, .D: HUBBARD. 377
PBA a ea i a ea a OP Daas RA ANS, SS Be nh Shae 8 LE

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MAGMATIC DIFFERENTIATION IN HAWAII

REGINALD A. DALY
Massachusetts Institute of Technology, Boston, U.S.A.

INTRODUCTION
SPECIAL PETROGRAPHY
Porphyritic Gabbro of the Uwekahuna Laccolith
Ultra-femic Olivine Basalt, Flow of 1852
Andesitic Basalt, Upper Slope of Mauna Kea
Trachydolerite of Summit Flows, Mauna Kea
Lherzolitic Nodules in the Summit Lavas of Mauna Kea
Notes on Other Lava Flows, Studied Microscopically
Projected Blocks at Kilauea and Hualalai
Average Composition of Hawaiian Basalt
THEORETICAL CONSIDERATIONS
Origin of the Ultra-femic Types
Origin of the Less Femic Types
Parallel Differentiation in Other Oceanic Islands
SUMMARY AND CONCLUSIONS

INTRODUCTION

Though the Hawaiian Islands are largely basaltic, it is already
apparent that they contain igneous types of considerable petro-
graphic diversity. The species so far discovered range from ultra-
femic basalts and intrusive porphyry, with less than 46 per cent
of silica and less than 2 per cent of alkalies, to the phonolitic
trachyte of western Hawaii, with 62 per cent of silica and more
than 13 per cent of alkalies. No sediments of the ordinary silicious
kinds appear to enter into the composition of the islands or of their
basement. Acid crystalline rocks of the gneissic or granitic order
Vol. XIX, No. 4 289

290 REGINALD A. DALY

also seem to play no réle in the petrogenesis of the archipelago.
Hence, some of the chief complications in the history of igneous
magmas which have invaded the continental plateaus, that is,
complications due to the assimilation of such highly varied country-

x Puu Anrahule Nee i

SSsss True North SS

xfuu Waawaag

atVudlalar

KAILUA

Wrohuaweorveo S
Sink e j BS Ue House

WL MP Ailowea Sith

20 Arm.

Fic. 1.—Locality map, showing positions of some of the dated lava flows in Hawaii;
also original localities of specimens chemically analyzed (dots numbered 1 to 4):
1, gabbro of Uwekahuna laccolith; 2, olivine basalt of 1852 flow; 3, andesitic basalt;
4, trachydolerite.

rocks, here seem to be absent. This relative simplicity of condi-
tions makes the petrogenesis of a deep-sea archipelago worthy of
attention quite independently of its own intrinsic importance.
The problem of origin here becomes largely, though not altogether,

MAGMATIC DIFFERENTIATION IN HAWAII 291

a matter of pure differentiation. An inspection of the results so
far attained in Hawaiian petrography clearly suggests the nature
of the local primitive magma, namely, basalt, and shows the march
of magmatic differentiation in the main island, from that parent
species to the less voluminous rock-types which have so far been
discovered.

The first part of this paper is devoted to a description of rock-
types forming part of a collection made by the writer in 1909.
From the facts won in that reconnaissance, and from those already
published in the writings of J. D. and E. S. Dana, of Lyons, Phillips,
Silvestri, Cohen, Méhle, Maxwell, C. H. Hitchcock, Brigham,
Dutton, Cross, and others, an induction has been made as to the
probable origin of the rock species in Hawaii. A brief statement
of the reasoning on which this tentative conclusion is based occupies
the second part of the paper.

The four new rock analyses and the analysis of phenocrystic
olivine were made by Mr. G. Steiger, chemist of the United States
Geological Survey. For these excellent data the writer’s sincere
thanks are due to him, and to Dr. G. O. Smith, the Director of the
Survey, who generously acceded to the request that this work
should be undertaken by the able experts of the government
laboratory.

SPECIAL PETROGRAPHY

Porphyritic gabbro of the Uwekahuna laccolith—About two
hundred meters north of the Uwekahuna triangulation station,
the western wall of the Kilauean sink exhibits a patch lighter in
color than the average rock in the cliff. This patch is visible
from the Volcano House and the writer made an early visit to this
part of the sink. (See locality marked ‘‘1” in Fig. 1.) Nearing
the place, it was observed that the light-tinted rock was more
massive than the lavas above and below it. Large blocks of the
rock had fallen from the cliff and many were plainly seen to have
been derived from the lighter-colored mass, which was gabbroid
in habit. With a little trouble the writer was able to scale the cliff
for the vertical distance of about 20 meters, necessary to reach the
lower contact. There the gabbroid rock showed a distinctly
chilled phase in a contact shell several decimeters in thickness.

292 REGINALD A. DALY

The upper contact was quite inaccessible, by ordinary climbing,
though it might, perhaps, be reached with the aid of a rope let
down from the top of the cliff. However, the coarse grain of the
holocrystalline rock and the relation of the mass to the overlying
ash-beds show without question that it is intrusive. The section
_given in the cliff is that of a laccolith, with a width of 160 meters
and a maximum thickness of about 20 meters. The ash-beds
above are uparched and conformable to the upper surface of the
laccolith, except at the southern end, where they are cut across
at a low angle by the gabbro. The massive lava flows overlying
the ash beds are little, or not at all, deformed by the intrusion.
-Some of the upper flows may be younger than the laccolith, but
it is possible that all the overlying flows are the older and that the
lack of deformation in them is due to the lateral crowding and
condensation of the loose ash-beds by the laccolithic magma. -

The gabbroid body may conceivably represent the crystallized
product of a subterranean lava stream of great length, but its
deformation of the overlying ash-beds is characteristic of laccolithic
intrusion and it seems just to describe the mass as a true laccolith.

The intrusive rock is dark gray in color, and slightly porous.
It is porphyritic, with phenocrysts of olivine. These are so nu-
merous that the rock appears, at first glance, to be somewhat
coarsely granular. In the hand-specimen the phenocrysts appear
roundish, and only rarely idiomorphic. Some of them are of the
usual olive-green color, but most are iridescent on the surfaces of
fracture, with the beautiful blue, green, and bronze tints of a pea-
cock’s feather. Though the rock in general is extremely fresh,
this iridescence seems to be due to an incipient alteration of the
olivine to serpentine, which is mixed with numerous, minute
grains of iron ore.

Under the microscope, the idiomorphism of the nearly color-
less, pale brownish olivine is more clearly manifest. It occurs in
individuals reaching 4 mm. or more in length. The ground-mass
is composed of plagioclase, augite, ilmenite, and magnetite; the
chemical analysis of the rock shows that a little apatite must be
present, but not a single crystal of it was demonstrable in the thin
section. The ground-mass varies irregularly from the hypidio-

MAGMATIC DIFFERENTIATION IN HAWAII 203

morphic-granular to the diabasic. The thin-tabular plagioclase,
reaching 1 mm. in longest diameter, seems to be throughout the
basic labradorite, Ab, An;. The pale brownish augite has normal
habit, the major diameters reaching 0.8 or 1.0 mm. There is
nothing unusual about the minerals of this rock and further descrip-
tive details are superfluous.

An analysis of the rock, by Mr. G. Steiger, gave the result shown
mecol, cor Mable I:

TABLE I
I Ia 2
SHOW abso abr 46.59 777 48.13
HEN O setae aenieeons 1.83 .023 87
INO Sale ok aiee 7.69 O75 6.50
Fe,0, Byer b ten LAD or4 a, Git Calculated Norm of r.
Cr Oy ss. ca nite) OOD, 5) | eae, oe
FeO oo... 10.40 ae ae a ae
aay sree gana : - ee a AMOTthItesepaa yee 13.90
Eiaumeaeees : Shey cats Diopside- | kere naal 48
Mee Tera Hh) “545 rans Hypersthene...... 17.06
AO spec bees Lee non De Olivine ea Bile 22
a ese es Be, rE = lilimenitey an ee 3.50
HO aaa = 3 “5 Magnetites 2.9.0 3.225
HLO+ : nN 1.62 Chromiteser ee #22
DOr 37 eae Apatite tees servo: 31
Ocean ae sae .OOI a5 Wiese :
COT ia: None Wereverin Tones eee (afc eemare vena nd ueimc of
SOketerne ce None Meise A sce he
BaO Sache ieee None Higa da Nila art eS)
StO were sos None Satis hen eR ea gaa
Tad Osaka oe None BS was ang Py alist ce
100.53 100.00
Sp. gr. 3.001

ir Porphyritic gabbro of the Uwekahuna laccolith.
ta Molecular proportions in 1.
2 Average analyses of three typical wehrlites.

Using the chemical analysis and the Rosiwal optical method,
the minerals have been calculated to form the following weight

percentages:
Olivinemeenes cee eo ore een eis 40.0
JANTICAT OS) 5 co bea Gilet ten Seo ee a 31.0
Labradorite..... Ae Aa ie ESP eRe ReEE 27.0
Magnetite andulmenitese:< 25-21-25) Ley,
PAD ELLeMnr per ciihs crn eait hug cece cnamanlen, B3

204 REGINALD A. DALY

In the Norm classification the rock falls in the domagnesic
subrang, wehrlose, in the permiric section, wehrliase, permirlic
rang, wehrlase, and section hungariare, of the dofemane order,
hungarare.

According to the accepted Mode classification the rock is an
ultra-femic porphyritic olivine gabbro or gabbro porphyrite. The
analysis is very similar to the average of three typical wehrlites
entered in Part II of Osann’s Bevtrige zur chemischen Petrographie.
See column 2 of the accompanying Table I.

Ultra-femic olivine basalt, flow of 1552.—Following the trail
from the Volcano House to Mauna Kea, the writer crossed the
lava which, in 1852, flowed out on the Hilo slope of Mauna Loa.
The trail traverses this lava at the 6,100-foot contour (see locality
‘““2” in Fig. 1), where the flow is about 1.5 kilometers in width.
The lava is of the aa or block type and much work with sledge
hammers was necessary to make a trail passable even for the hardy
pack-animals of the island. The broken rock is, of course, quite
fresh, and its numerous olivine phenocrysts, of unusually great
size and of beautiful color and brilliance, made a remarkable effect
for the eye as one walked or rode over the lava. The development
of phenocrystic olivine is greater in this flow than in any other
seen by the writer during several hundred miles of travel in Hawaii.

The hand-specimens of the lava have a dark-gray, lithoidal
ground-mass, in which the abundant, bright yellowish-green
olivines are conspicuously set. As usual with the aa type of lava,
the gas pores are large and irregularly distributed through the
rock. They were elongated and flattened during the flow of the
stiffening lava and the longer diameters of the pores reach three
or more centimeters in length. The idiomorphism of the olivine
is often manifest to the unaided eye, and is still more evident
under the microscope. The individual crystals are often more
than one centimeter in diameter. No other mineral is pheno-
crystic.

The microscope shows a rather surprising contrast in the grain
of the ground-mass, which is of diabasic structure, with thin
tables of plagioclase, seldom over o.1 mm. in length, separated by
augite granules of even smaller diameters. Magnetite and prob-

MAGMATIC DIFFERENTIATION IN HAWAII 2905

ably ilmenite form the only other visible constituents, though a
little apatite must occur. No glass and no sulphide mineral
could be found in the ground-mass.

The olivine includes a little magnetite, in small euhedral and
anhedral crystals. A few brown, roundish inclusions may be
glass. In thin section the olivine is nearly colorless with a gray
tinge. It was easily isolated and then freed of impurities except
for the minute inclusions described. Its ee, by Mr. Steiger,
gave the following result:

Mol. Calculated Composition

SIO rears 4o.42 2070 ‘ Per cent
TOs ee... 08 OOL . Forsterite Se ne ee ee 82.29
LOM a er: 32 003 F ayalite chien Rene re yaya ie 15.94
iOK. baa 1g or HPephroitenmerinc ere 0.20

COW .18 .OOT
ISSO) coos nae II.44 .159 ; 98. 43.
NiO “To or PATIOLUULGC pel fewelerayer teeters: 0.97
INGO ees 34 005 IMIR VERAMNYS G oy ocaGgonap ess 0.23
MeOn ..: 47.08 1.168 ililmenitie serene eee epee: 0.15
CRG eee 25 004, Chromite) ees Speen 0.22
2 INGO’ Westra erseeny eat ae 0.34

100.34
I.QI
Sp. gr. 3.369

Granditotaltei et ae. 100.34

So far as known to the writer, this is the only total analysis of
any Hawaiian olivine yet made. Penfield and Forbes found ro. 3
per cent of FeO in olivine collected by J. D. Dana on the south-
eastern shore, south of Hilo. The optical angle (2V) for this
mineral was calculated to be 91° 2’, and the authors found that
chrysolites containing about 12 per cent of FeO show a value of
go for 2V in yellow light.t The olivine now described has 11.44
per cent of FeO, and hence it would be extremely difficult to be
quite certain whether the mineral is positive or negative. No
special work has been expended in the attempt to determine that
point.

The minute plagioclase tables of the ground-mass gave maximum
extinctions corresponding to the mixture Ab,; An,;. The augite
is pale, practically colorless in thin section, and has no noteworthy

1S. L. Penfield and E. H. Forbes, Amer. Jour. Sci., I (1896), 133

296

peculiarities.

REGINALD A. DALY

A study of the chemical and mineralogical analyses

showed that it must be rich in FeO and relatively poor in MgO.

The magnetite and ilmenite are abundant in the ground-mass.
Mr. Steiger’s analysis of the rock gave the proportions shown

in Table II.
TABLE II
I Ia
SiQi eee 48.57 .810
ABO Fase esenrsr. care 1.48 .O19
UN OF dea cn te To. 51 1 Calculated Norm
Hes Oyee nen 2.10 .OT4
CuO eee. .10 -OO1 @xthoclases i. aes 2.22
HeOens se. 9-45 -132 AlDItG: 4 en erence ae T3302
Win OF ce te .16 .OO1 Anorthitesr ue Gamer 20.29
INTO 32 Sisson aes 08 -OOT Diopsidenaan ee eee Tisane
IMO re aciacays 17.53 438 Hypersthene............ 23.98
Ca@yer esa 8.06 -144 Olivine 335.0 oe 18.49
INGO) Gs Sino doo T.59 026 mentite i nieee esas oe 2.89
KOR ar 34 004 Mapnetites tn. oc seee 3.25
EEO ee se .I0 APAtIte eet ee es aH
H,0+ 37 vee Waterton ee 47
DEH O Fee ecplarcante .19 .OOI
COR ae ie: None 100.63
100.72
Sp. gr. 3.005

t Ultra-femic olivine basalt, lava flow of 1852.

1a Molecular proportions in 1.

Using the Rosiwal method, checked by the analyses, the Mode
(weight percentages) was calculated to be:

Olivine

Magnetite
Apatite

@p:8) (ee! se! ce- eels \enieil(od vise) re, 10) 1.0) 19\1e 1s \ie\ ere eis) 0 <8\50

I00.00

Assuming the probable values of the specific gravity for each
mineral, the specific gravity of the rock was calculated to be 3.16,
which agrees satisfactorily with the actual value, 3.065, found by
the proper weighing of coarse powder of the rock.

In the Norm classification the rock enters the hitherto unnamed

MAGMATIC DIFFERENTIATION IN HAWAII 207

domagnesic subrang, in the permiric section and permirlic rang
of the dofemane order, hungarare. If a name for this type in the
Norm classification is desired, the subrang may be called hilose,
from the name of the chief port of the island, Hilo. The corre-
sponding names for the rang-section and rang would be hiliase
and hilase. The hitherto unnamed section of the order may be
called hawaziare.

According to the Mode classification the rock is an ultra-femic
olivine basalt of an extreme type. In both chemical and min-
eralogical analyses it approaches the still more abnormal type
represented in the Uwekahuna laccolith.

Andesitic basalt, upper slope of Mauna Kea.—On the eastern
side of Mauna Kea, from the 6,o00-foot contour to about the
12,000-foot contour, the abundant lava flows seem to be very
uniformly composed of a rock species which is intermediate between
typical olivine basalt and a true augite andesite. These lavas
are almost entirely of the aa or blocky type; pahoehoe surfaces
are only locally developed and, within the area described, seldom,
if ever, show the perfection so often illustrated in Mauna Loa.
Among the specimens collected, one taken at the 11,000-foot con-
tour (see locality “‘3” in Fig. 1), 4,500 meters S 75° E of the sum-
mit of Mauna Kea, was selected for chemical analysis. Its descrip-
tion would doubtless apply, with but unimportant change, to the
average lava of all this part of the great volcano.

The rock is dark gray, fresh, and strongly vesicular, again
showing the great irregularity in the size and distribution of the
vesicles, which is usual with aa lava. The only minerals micro-
scopically visible in the dense ground-mass are a few phenocrysts
of yellowish-green olivine and tabular plagioclase, with maximum
diameters of 2 mm. and 3 mm. respectively. In thin section a
few idiomorphic phenocrysts of augite, reaching 1 mm. in length,
are to be seen. Estimates made by the Rosiwal method show that
the olivine phenocrysts form no more, or little more, than one
per cent of the rock by weight, and that the augite phenocrysts
occur in about the same proportion. The very abundant plagio-
clase phenocrysts have cores averaging about Ab, An, in composi-
tion. They are often surrounded by a very thin shell of oligoclase

298 REGINALD A. DALY

averaging Ab, An,, as indicated by zero extinction on (oro). That
shell is surrounded by a still thinner, outermost shell, which gives
an extinction of about +5° on (oro) and is either a more acid
oligoclase or else orthoclase.

The ground-mass has a pilotaxitic to diabasic structure and
consists of plagioclase, augite, and magnetite, each in high pro-
portion. A few round granules of olivine may also be discerned.
The plagioclase is often zoned, with a somewhat larger relative
development of the acid shells. Again, the outermost shell may, in
many cases, be alkaline feldspar, but the very fine grain prevents its
actual demonstration. No sulphide mineral was visible in the rock.

Mr. Steiger’s analysis yielded the result shown in column 1 of
Table III.

TABLE III
I Ia 2
S103 eo 49.73 .829 49.10
DEO RG aii prcete 3.05 .038 ny /
IMO och bon eiata 16.30 .161 14.02
es Olen ae Voix .048 5.62 Calculated Norm of 1
JRSO) ties Snes c 3.98 056 8.68 pices Tammie tacalien trays Eo
Mn@uane ee "5) 003 54 Quartz oe 1.86
MeOr nnn. 4.06 IOI 6.42 Orthoclase........ Dish 2
CaO EA We re 8 PpM any) p28 Q.10 Albite, .. 0.022%. 34.58
INaO ee 4.12 066 Bea Anorthite........ 20.85
KOnn Aree 1.03 020 1.04 Diapsides means 6.78
EO ee eee 8 eink ) Elypersthene 72-2. 910.60
Ose ae 54 Rae ects lelilmenitessr aan 5.78
PiOne es oh TOO6 Pi, Ne Magne tite mace emaoy
COR tines None Se ee ae Rr IEVendartite sansa Ae.
Ba@ue ea 03 capme WhihiMe ue ree eAtpartlite se ieuat aera 1.86
SrOisee cate None neath | ay Sten |) Water ete. 2 > nctte 5
Ni OMe ier ae OAR ah |e hey sore eed |e Utes ||
CrOne cue Nome: Wilks. wesoe tS eee | 100. 27
VAR Ove Rn Bieceme stor WAG tere Wneeeiso tie eee a \|
SOW ee case INGME. 2) tS ees ie ene ||
Digs Maer NOTE Elekta Nec ee
TOORSS 100.59 |
Sp. gr. 2.911 |

xt Andesitic basalt, lava flow at 11,000-foot contour of Mauna Kea.
ta Molecular proportions in 1.
2 Average composition of norma! Hawaiian basalt.

By the Norm classification the rock enters the dosodic subrang,

andose, in the alkalicalcic rang, andase, of the dosalane order,
germanare.

MAGMATIC DIFFERENTIATION IN HAWAII 299

According to the Mode classification, it is an andesitic basalt,
transitional in type between olivine basalt and augite andesite.
Its specific gravity was determined on a specimen which had been
coarsely powdered to avoid an error due to the porosity of the
rock. For comparison the calculated average for the basalt of
Hawaii is given in column 2.

Trachydolerite of summit flows, Mauna Kea.—Brigham and
others long ago noted the occurrence of “‘clinkstone”’ at the top
of Mauna Kea, and the present writer had opportunity to make
some study of this rock in place during the 1909 reconnaissance.
Near the 13,000-foot contour, he found several flows of lava of
much lighter color than the staple olivine basalts of Hawaii, or
than the abundant andesitic basalt just described. These flows
all seem to be short, generally less than one kilometer in length.
Their terminal scarps have been little affected by frost or other
weathering agents, and the steepness of these scarps indicates a
notable degree of viscosity during the outflow. In some cases
these flows could be seen to have emanated from the fissures in
the summit cinder-cones. Though the pyroclastic material of
the cones is generally altered (to deep brown and red tints), it
appears to be chemically identical with that composing the always
fresh, light-colored flows.

The ‘‘clinkstone”’ habit is due largely to a noteworthy lack of
vesicles in the lava. Though some large gas-pores always occur
in the thin surface shell of each flow, its interior is often nearly
or quite free from even small pores. This homogeneity of the
rock is, doubtless, chiefly responsible for the extremely sonorous,
metallic sound given out when the lava is broken by the hammer.

For special examination, typical specimens were taken from
a flow which issued from the eastern flank of the cinder-cone
named ‘‘Poliahu”? on the government map, at a point about
350 meters north of the summit pond. The description of the
lava may be based on one specimen, which has been chemically
analyzed.

The rock is of a fairly light, slate-gray color, is non-porous, very
dense, but holocrystalline. A few thick tables of plagioclase, from
I mm. to 2 mm. in length, represent the only constituent determi-

300 REGINALD A. DALY

nable to the unaided eye. There is merely a hint at flow-structure,
registered in a rude parallelism of these phenocrysts.

Under the microscope it is seen that a few, small, anhedral
olivines, and somewhat more numerous augite crystals—none,
in either case, surpassing 1 mm. in greatest diameter—are to be
added to the abundant plagioclase (averaging labradorite, Ab,
An,) in the list of phenocrysts.

The ground-mass shows a confused crystallization of augite,
magnetite, and apatite, in a dominant felt of feldspar. A few
grains of an allanite-like mineral, pleochroic in tones from deep —
brown to pale greenish-brown, form the only other accessory
material. No sulphide is visible in thin section. Most of the
ground-mass feldspar is plagioclase—acid labradorite or basic
andesine—twinned on the albite law. Another feldspar arranged
interstitially in relation to the plagioclase has the low double
refraction and lack of twinning characteristic of orthoclase. This
mineral occurs in such minute individuals that a full demonstra-
tion of its nature has not been possible. Many of the labradorite
phenocrysts are surrounded with shells of alkaline feldspar with
extinctions on (o10) ranging from +5° to +o° 30’, suggesting
orthoclase and soda-orthoclase, and it is very probable that both
of these represent the last product of crystallization in the ground-
mass. The total alkaline feldspar does not form much more than
rs per cent of the rock by weight.

Mr. Steiger’s analysis of this rock gave the proportions shown
in col. 1 of Table IV.

By the Norm classification the rock is to be referred to andose,
the same subrang as that calculated for the andesitic basalt just
described. According to the Mode classification, this rock, con-
taining an essential amount of alkaline feldspar, is best included
among the trachydolerites, as defined by Rosenbusch, though
near the basaltic end of that series. In column 2 of Table IV the
average of the 34 analyses of trachydolerites, named as such in the
last edition of Rosenbusch’s Elemente der Gesteinslehre, is given
for comparison. Column 3 gives Lyons’ analysis of a more alka-
line, less femic, trachydoleritic type from the neighboring volcanic
pile in Kohala."

tA. B. Lyons, Amer. Jour. Sci., CLII (1896), 424.

MAGMATIC DIFFERENTIATION IN HAWAII 301

Lherzolitic nodules in the summit lavas of Mauna Kea.—The
chief difference between the andesitic basalt and the trachydoler-
ite is mineralogical; orthoclase is an essential constituent in the
latter, and has wholly, or almost wholly, failed to individualize
in the basalt. The two types are almost alike chemically. They
also resemble each other in carrying rather numerous ultra-femic
nodules of all sizes up to to cm. in diameter. These are always
rounded and usually roughly spherical, of coarse grain, and of a

TABLE IV
I Ia 2 3

SiOsea ee 50.92 .840 49.20 58.06 |
Blt OS ets se: 2).55 032 1.68 1.88
ENO a oiatye bs E750) e713 16.65 18.21 Calculated Norm of 1
IPCLOM ch Sabo c 3.80 .024 4.76 4.87
Be Ope secs a: 6.69 093 5.36 2.01 || Orthoclase....... 11.12
Min @ieaee) 20 oor ss 36 ANIONS Soir aOner 36.16
IN Wax O) aan eens 3.90 097 4.43 1.59 Anorthite..... 7.2: 23-35
CaO 6.07 .125 TTA) al 33120 Wiopsideemaarinsne: 6.98
INewORe es 4.28 0609 4.54 6.12 Hypersthene...... 7.21
KC Ona. 6. 1.86 020 3.10 2.75 || Olivine........... 2.98
EOFS oe CiGtY °) | ld a a a De ||| Uhooverantrey on Solu do 4.86
eLOnS aes 70 eee Be Mali wears || Magnetite 2... .. SiS
Ope an a eoee 40 003 .60 P6s,) || Apatite. 2s. 3103
COR ek None Ah fad cen Geena RD WMI ogi auntie 1.14
INI OM ete INGOTS APNE iets sial ine teres sence dk coe aa |
CrOnnes ..{. None ps Panda ioe scree ti age. 31) TOO. 30
Cu@Mietcy een il Lane. se |

100.30 100.00 99.99

Sp. gr. 2.761

t Trachydolerite, lava flow at 13,000-foot contour on Mauna Kea.

ta Molecular proportions in 1.

2 Average of 34 analyses of trachydolerites named as such in the third edition of Rosenbusch’s Ele-
mente der Gesteinslehre.

3 “Andesite” from Waimea, Kohala district, in northwestern Hawaii.

dark green or brownish-green color. They seem to be rather
uniformly composed of dominant olivine, much diallage, subor-
dinate or accessory plagioclase, and a little magnetite or ilmenite.
Apatite has not been demonstrated in thin section.

The nodules occur in the trachydolerite of the cinder-cones as
well as of the adjacent flows. In a few cases observed, the nodules
of the cinder-cones formed ellipsoidal bodies without any adhering
trachydolerite, as if each of these nodules represents a solid mass
exploded out of the vent and freed from liquid magma by the

302 REGINALD A. DALY

violence of the explosion. More generally, the nodules occur in
projectiles largely composed of the normal trachydolerite. The
specific gravity of one ellipsoidal nodule about 8 cm. in length was
found to be 3.316; it is almost entirely free from feldspar.

The nodules inclosed in lava are best displayed in the frost-
riven felsenmeer surrounding the summit pond. One of these was
sectioned and specially studied. The plagioclase was found to
have the composition of acid anorthite, Ab; Any. A few small
tables of the feldspar and rare granules of olivine are inclosed
in the diallage, but in general, the anorthite is interstitially
developed between the olivine and diallage crystals, which seem
to have crystallized nearly simultaneously and after the iron ore.
The pyroxene is much more often idiomorphic than is the olivine.
The specific gravity of this nodule is 3.111.

The Rosiwal method afforded the following estimate of its
weight percentages:

Olivines: 6.62 eee ene. a cues ih eneranine 62
Diallagerk scsi ie een a ara te staeeenelarays 26
Amorthnite mee jesnone cir ci nates meetocteie stones unit
Macnetiteand ilmemte: 022 se seen I

TOO

Assuming the olivine to have the same composition as the
olivine in the lava flow of 1852, and the diallage to have the aver-
age composition of basaltic augite,* the nodule was calculated

to have, approximately, the composition shown in column 1 of
Table V.

TAB ER WV
ag 2

SiO, Sates enn a Nee 43-4 43.78
A OG. triers tests cee 58 2
INNO} Soe peawie 6 ccarante c Bas 5.02
Fe.0; Ta i 0)
ie Olena setae toners Bey & Ay
ING OW mes eerste eleba 32.8 33.08
CaO sehen ees 7.4 6.62
INasO) ee ae see near +8) 1.06
MnO+K.,0+P.0; ... faa say

100.0 100.00

™See Journal of Geology, XVI (1908), 410.

MAGMATIC DIFFERENTIATION IN HAWAII 303

Column 2 gives the average composition of four typical lherzo-
lites.t In spite of any uncertainties as to the exact compositions
of the femic minerals, it is clear that the nodule is, chemically, a
lherzolite.

The writer believes that these nodules are not exotic, but rep-
resent segregations in their respective magmas just as truly as do
the olivine phenocrysts. Easy transitions in size are to be found,
in the field, between large, single phenocrysts of olivine and the
largest olivine nodules observed.

Notes on other lava flows, studied microscopically.—On the trail
from the Volcano House to Mauna Kea, at about the 6,000-foot
contour (see Fig. 1), the flow of 1880-81 was found to be olivine
basalt of the pahoehoe type. The adjacent flow of 1855 is similarly
composed but has local aa phases. Still farther north the trail
crosses the ‘‘ancient flow” shown on the government map (marked
‘“‘ancient” in Fig. 1); this is an olivine basalt with typical aa
habit. At the wagon-road between Waimea and Kailua, the great
flow of 1859 is an olivine-poor to olivine-free basalt with both aa
and pahoehoe phases.

Projected blocks at Kilauea and Hualalai.—E. S. Dana has
already described the common, basaltic types of rock represented
in the solid projectiles thrown out in the rare explosions which
have occurred at Kilauea.?, The present writer has made a micro-
scopic examination of seven different specimens of the projectiles
sampled at intervals along the edge of the Kilauean sink from
Uwekahuna to Kilauea Iki. All of them are holocrystalline and
they are non-vesicular or else nearly free from pores. In the
coarser blocks the pores are true miaroles, into which the feldspar
and augite, showing crystal facets, have grown. The rock species
included in this small collection are: basalt poor in olivine; typi-
cal olivine diabase; olivine-free diabase; and a typical, relatively
coarse-grained olivine-free gabbro.

Of these, the gabbro is the only type worthy of special remark.
It composes several of the projectiles occurring on the road from
the Volcano House to Kilauea Iki, near Waldron’s Ledge. The

tSee Proc. Amer. Acad. Arts and Sciences, XLV (1910), 226.

2 See J. D. Dana, Characteristics of Volcanoes (New York, 1891), 344.

304 REGINALD A. DALY

visible blocks are all angular, quite fresh, and 20 to 50 cm. in
greatest diameters. No olivine is visible in the fairly dark-gray,
granular rock, either in the field or under the miscroscope. The
essential constituents are labradorite, Ab, An;, and a strongly
tinted, greenish-brown, non-pleochroic augite, with an unusual
amount of iron ore, probably ilmenite. Apatite in needle form
is very abundant; therein this rock contrasts with nearly every
Hawaiian rock so far studied in thin section. The stout augite
prisms, which lack the diallage parting, reach 4 mm. in length;
the thick tables of labradorite are often 5 mm. in length and the
plates of ilmenite measure 1 mm., or less, to 5 mm. in length.
The structure of the rock is not basaltic or diabasic, but typically
hypidiomorphic-granular.

On the summit of Hualalai the writer sampled three projected -
blocks which occur in a thin pyroclastic deposit veneering this
lava-formed (olivine-basalt) volcano. Two of them are holocrys-
talline equivalents of the normal olivine basalt of the island.
The third is a coarsely granular rock almost identical in compo-
sition and grain with the type forming the laccolith at Uwekahuna;
- itis an ultra-femic gabbro, with high idiomorphism in the abundant
olivine.

Average composition of Hawaiian basalt.—Of the extant analyses
of the basalts from the main island, nineteen, which were made
from fresh and typical material, have been selected for the purpose
of computing the average composition of the dominant rock type
of the island. Most of these analyses are quoted in C. H. Hitch-
cock’s Hawaii and Its Volcanoes (Appendix D). Ten are taken
from O. Silvestri’s paper in the Bolletino del R. Comitato Geologico
Italiano (XIX [1888], 185); four from E. Cohen’s paper in the
Neues Jahrbuch fiir Mineralogie, etc. (1880; II, 23); and four
from A. B. Lyons’ paper in the American Journal of Science (II
[1896], 424). Mr. Steiger’s analysis of the 1852 flow and _ his
analysis of the chemically similar porphyry forming the small
laccolith at Uwekahuna, Kilauea, are also included, making twenty
analyses in all.

The calculated average is shown in the first column of Table
VI, where the second column gives the writer’s result in averaging

MAGMATIC DIFFERENTIATION IN HAWAII 305

198 analyses of fresh basalts taken from Osann’s great compi-
lation for the world (analyses published between 1884 and 1900).

TABLE VI
Average Hawaiian Basalt | Average World Basalt

S(Opoy savucsoos shone 49.10 49.06
ABO Coie see rental Aaa eae Te 72 1.36
aN Oe Be crete eh cS 14.02 TO
ESO Maree me cat asean ener G02 5.38
IRSO) Cie dears tetas hos aan 8.68 Oy
Mia Oe etch, geen en -ei 54 or
INCOM pees ter renee 6.42 6.17
CaO Bee ee Litas 9.10 8.95
IN@A0) a aagivg da coouae 3.24 3, 5851
IR O) seiithe Non ain Bema amen 1.04 T52
JELLO) paiiereret ech eet OF 74 1.62
1eOy O 0.005 bO0 Olona LOS pe) 45

100.50 100.00

The close correspondence of the two averages is obvious at a
glance. In fact, it has been found that the greater the number
of reliable analyses included, the nearer the Hawaiian average
approaches the world average. Though perfect averages might
show the former to be slightly the more femic of the two, it is
certain that the staple igneous type in the mid-oceanic Hawaii
are chemically very similar to the average basaltic magma poured
out on the continental plateaus.

THEORETICAL CONSIDERATIONS

Origin of the ultra-femic types—In columns 1 and 2 of Table
VII the analyses of the Uwekahuna laccolith and of the 1852 lava
flow are respectively entered. Column 3 gives the mean of these
two analyses. Column 5 gives the average analyses of four typi-
cal lherzolites, calculated as water-free. Column 6 shows the
calculated composition of the average Hawaiian basalt, while
column 4 gives the mean of columns 5 and 6.

A comparison of the markedly similar columns 3 and 4 suggests
that the ultra-femic magmas of the island are due to the mixture
of a large amount of the ferromagnesian and cafemic (calcium-
iron-magnesium) constituents of the basalt with the average basalt
itself, though, of course, not necessarily in absolutely equal pro-

306 REGINALD A. DALY

portions for the two parts of the mixture. Such a mixture could
occur in the main volcanic vents at great depth, provided that
the ferromagnesian and cafemic molecules settled down from the
magma in the upper part of the vent, where gravitative differentia-
tion was taking place.

This explanation of the ultra-femic phases is favored by the
consideration that no fact in the field relations opposes the assump-
tion of a very deep, direct source for these heavy magmas. The
flow of 1852 emanated from a fissure in Mauna Loa, about 1,300
meters below the top of the main conduit of the island; and the
laccolithic body exposed in the wall of Kilauea is 3,000 meters

AVM BIS, WAUL
I 2 3 4 5 A y

Laccolithic) Flow of Mean of Mean of Average Hiatus

Porphyry 1852 I and 2 5 and 6 Lherzolite Basalt
SIO eee 46.59 | 48.57 47.58 46.65 43.78 | 49.19
AM Os eee 1.83 1.48 1.66 92 51 T72
ENO ow onc 7.69 10.51 g.10 9.52 5.02 14.02
FeO; .. 220) 2.19 2.20 a 5.18 5.62
He @ mene 10.46 9.45 9.95 pets Cay eae ce BATT 8.68
IMENO) ag oe .18 16 aL7 30 06 54
Mig. Om ee 21.79 Te 7enG2 19.66 19.75 33.08 6.42
Ca@Oiecrvar TA 8.06 Teil 7.86 6.62 9.10
Na,O .. Te 313 1.59 1.46 Dats 1.06 Bue
Ke Oi 28 34 ao 67 30 1.04
ETS Oi eke 4I AT 44 Bie hie See cam nana aae 74°
PO ree 530i 19 ste 5 8G; Or . 28
Cr.O; etc... 215 .18 One ec. eee re Se pac case fleet mete

TOO 530 |= LOOM 72 100.63 100.46 100.00 | 100.59

below the same level. In either case, the level in the conduit
where it was tapped to form the erupted body may have been
several kilometers still lower down in that conduit.

Origin of the less femic types.—The hypothesis that the ultra-
femic rocks represent the products of mixture of the average basalt
with the ferromagnesian and cafemic substances (more specifically
the molecules represented in the phenocrysts of the normal basalt)
settled down from higher levels in the main Hawaiian vent, implies
that more salic and more alkalic magma is formed at those higher
levels. According to the thoroughness of the gravitative differen-
tiation, the less dense magmas would vary in the degree in which

MAGMATIC DIFFERENTIATION IN HAWAII 307

they would be more salic and alkalic than the parent basalt. As
a matter of fact, a goodly number of such derived magmas seem
to be represented in Hawai. Table VIII, columns 2-6, shows the
chemistry of the principal types to which this mode of origin may
be, at least tentatively, ascribed.

TABLE VIII
I 2 3 4 5 6

SiOs eee 49.10 49.73 50.92 58.06 61.64 62.19
IOS cb oe: (2 3.05 B35 THO Om a4 |augemnws 37
ALO; 14.02 16.39 17.59 To ee 9 alle Gee 17.43
FeO; Soe TES 3.80 EO 1. Mlyetaeneteca 1.65
He@y chs. 8.68 3.98 6.69 Parapet tril aes ca 2.64
MnO 54 528) 20 <3 Oa ale acaesaee 32
Wig) sc uiee 6.42 4.06 3.90 TSO, lec cites .40
CaOrns t: g.10 Teel, 6.97 3082 0) pret | Slee eae 86
Na,O aay 4.12 4.28 Geo ee akan | eae 8.28
KOR a. 1.04 1.93 1.86 MG fam melbiengads ae 5.03
Jal{O) solaiaiae 74 I.35 PRT At de wets ae area tteaeyi cu ge erabe ete a5
PI Oe: 28 84 .40 65 ‘eit .14
INGO) eto cll 4 eaeaoia BELO eI suerte care: OO he ate |eemal ees ole)

100.59 | 100.53 100.30 OC» oy I Geese 99.93
SDa liste ciara cuss 2.Q11 Der Oiemn nel eaben ace ty he Ie aia 2.6271T

tf Determined from hand-specimen collected by the writer. All three rocks for which specific
gravities are given, are holocrystalline.

1 Average analysis of twenty basaltic types in Hawaii.

2 Andesitic basalt of Mauna Kea.

3 Trachydolerite of summit, Mauna Kea.

4 “Andesite” (trachydolerite) of Waimea, Kohala district (analyzed by A. B. Lyons, Amer. Jour.
Sci., II [1896], 424).

5 “Augite Andesite from the Sandwich Islands” (silica determined by E. Cohen, Neues Jahrbuch
fiir Mineralogie, etc. [1880; II, 38]).

6 Phonolitic trachyte of Puu Anahulu (described by W. Cross, Journal of Geology, XII [1904], 510).

On p. 53 of the paper by Cohen, for which the reference has
been given, it is stated that in the rock collection there described,
four other occurrences of “‘typical augite andesites” in Hawaii
are represented. Two of the specimens were taken on Mauna
Kea; the other two were collected on this island, but the labels
failed to give their exact localities. No analyses were made of
these specimens, but, of course, one may trust Cohen’s well-known
skill in diagnosis and place all four rocks among the more salic
types of Hawaii.

From the table it seems clear that the strongly alkaline trachyte

308 REGINALD A. DALY

of Puu Anahulu and the “‘andesite”’ of Waimea are consanguine-
ous and that transitional types connect them with the distinctly
subalkaline, normal basalt of the island. The steady decrease
of the iron oxides, magnesia, and lime, and the corresponding
increase in silica, alumina, and alkalies are as systematic as could
be expected in a syngenetic series derived by the process of differ-
entiation already in part described.

The norms calculated for the analyzed types tell the same story.
They are summarized in the form here given:

Average Andesitic acach : 2

A ydolerite Andesite Trachyte
Hayate in é oesale 4 of M. Kea of Waimea of Puu Anahulu

salic: 225: 2: 53-94 68.41 70.63 85.09 86.74

Hemirca sere 45.70 30.41 28.53 14.75 12.45

Calculation shows that the alkalic members of the series were
probably not formed by a mere subtraction of ferromagnesian and
cafemic, phenocrystic material from the normal basaltic magma.
On the other hand, a positive addition of the alkalies seems to have
occurred when the more silicious types were developed.

The concentration of the alkalies in the upper part of an ini-
tially basaltic vent may conceivably be due to two principal causes.
In the first place the feldspathic or feldspathoid matter of the
basalt might individualize in liquid phases or as plastic or rigid
crystals, and, because of the low density of any of these phases,
rise in the magma column, just as the individualized olivine or
augite (in liquid or solid phases) must sink. Or, secondly, the
volcanic vent may become temporarily enriched in emanating
gases, which, as they rise, bring the alkalies with them in loose
combination.

Of these two possible causes the partial control by rising volatile
substances seems to be specially clear in intrusive bodies. The
writer has suggested that most of the alkaline rock types have
been derived from subalkaline magma through the solution of
limestone or other carbonate-bearing sediments.’ Thereby the
subalkaline magma is not only fluxed and so prepared for drastic

t Bulletin Geological Society of America, XXI (1910), 87-118.

MAGMATIC DIFFERENTIATION IN HAWAII 309

differentiation, but the carbon dioxide introduced from the sedi-
ment carries the alkalies with it as the gas rises through the magma.
An instructive series of experiments by Giorgis and Gallo bear
on this suggestion. They mixed the powders of various recent
Vesuvian lavas with water, and passed a current of carbon dioxide
through each mixture for a period of two months. Analyses
showed that the powders lost, on the average, 37 per cent of the
soda originally contained, the remaining constituents being but
little altered in amount. At high temperatures the upward
transfer of the alkali would presumably be much more rapid.

In the case of the Puu Anahulu trachyte or in that of the
Waimea “andesite,” the principal factor in the differentiation
may have been the solution of coral or foraminiferal limestones,
such as are known to be interbedded with the older lavas of the
archipelago. That the normal magma of the archipelago has
been locally affected by such solution is suggested by the occur-
rence of melilite and nephelite in the basalts of Maui and Oahu,
the melilite indicating an excess of lime and the nephelite showing
such desilication of the salic part of the magma as is expected
when it dissolves foreign lime. The carbon dioxide entering the
primary basaltic magma because of this solution of sedimentary
rock would belong in the “resurgent” class of emanations. A
special concentration of juvenile carbon dioxide in a basaltic vent
would, in an analogous way, tend to concentrate the alkalies of
the basalt at the top of the vent.

This hypothesis, that the decidedly alkaline rocks of Hawaii
have been derived from the normal, subalkaline basalt through
gravitative differentiation in the volcanic conduits, is supported
by the intimate field-association of the two classes of rocks, and
by the fact that the alkaline bodies are all of very small volume
as compared with the known mass of normal basalt in Hawaii.
The first-mentioned relation is obvious; the second is already
clear, even though the island has been covered only by recon-
naissance journeys. It is practically certain that the trachyte
of Puu Anahulu and vicinity, the most salic type and one very
conspicuous in the field, can be exposed at but very few and small

t G. Giorgis and G. Gallo, Gazetia (1906) [I], 137.

310 REGINALD A. DALY

areas at the present surface of the island. As expected on the
hypothesis, the alkaline types more nearly approximating the
average basalt in composition are much more voluminous than
the extreme phonolite-trachyte member of the series. In Mauna
Kea, at any rate, the trachydoleritic representative of the alkaline
species seems to be confined to the summit plateau of the volcano,
that is, to the region where it should occur if it were due to the
vertical differentiation of the basalt.

On the other hand, the dominant rocks on the broad summits
of Mauna Loa and Hualalai, and of Haleakala, in Maui, are
normal basalts, often rich in phenocrystic olivine.t There is no
doubt that the conditions were unfavorable to important differ-
entiation during most of the time engaged in the building of these
giant volcanoes. Similarly, the lava of the active vent at Kilauea
is basaltic and apparently has always been of that normal com-
position.

One reason for this contrast with Mauna Kea in its latest stage
is probably connected with difference of temperature, for the
differentiation of any of the commoner earth magmas seems to
take place only within a comparatively narrow temperature range
occurring just above the ‘“‘point’’ of solidification. That the
average temperature of the latest Mauna Kea vents was actually
lower than that characteristic of the active Mokuaweoweo on
Mauna Loa is suggested: (a) by the smaller size of the pipes on
Mauna Kea; (0) by the far greater abundance of pyroclastic
material on Mauna Kea; and (c) the correlative high viscosity
of the short, stubby flows on Mauna Kea. The latter were more
viscous than the average flow on the summit of Mauna Loa, not
merely or chiefly because of difference in chemical composition.

But a probably much stronger control is to be found in the

t—. S. Dana describes a group of ‘‘clinkstone-like basalts” (specific gravity,
2.82-3.00), free from olivine or very poor in it, which were collected at the summit
of Mauna Loa. These may represent incipient differentiation even at Mokuaweoweo.
Another, highly olivinic group of basalts (specific gravity 3.00-3.20) are, however,
associated in great volume. (See J. D. Dana, Characteristics of Volcanoes [New
York, 1891], p. 319.) The present writer found a similar variation in the basalts at

the summit of Haleakala, which are cut by dikes of compact, olivine-free rock sug-
gestively like the trachydolerite of Mauna Kea.

MAGMATIC DIFFERENTIATION IN HAWAII BEE

inhibiting convection which is so powerful in highly fluid columns
like those of the active Mokuaweoweo or Kilauea. In a paper
published in the current volume of the Proceedings of the American ‘
Academy of Arts and Sciences, the writer has indicated the prob-
able cause of the very energetic stirring visible in the Kilauea lava
column. The action is there called ‘‘two-phase convection,” as
it depends on vesiculation of the lava in depth. The gas-bubble
phase is formed through supersaturation of the liquid with juvenile
volatile matter. A small amount of vesiculation in depth must
lend much buoyancy to the magma, which rushes up the conduit
in periodic gushes; its place is taken by sinking magma that has
been rendered more dense by the escape of its included gas at
the surface. This type of stirring—incomparably more effective
than thermal convection can be in such a column—keeps the vent
open by transferring the abyssal heat to the zone of radiation;
and as well, tends to prevent differentiation because of the con-
tinuous, thorough mixing of components in the magmatic column.
A dormant state is introduced when the special supply of gas is
largely exhausted. Then two-phase convection is slowed down,
and if the other conditions permit, gravitative differentiation may
affect the column more or less. Revival of activity is the result
of a renewed concentration of juvenile gases rising into the con-
duit from the feeding magma chamber. The consequent strength-
ening of two-phase convection means a speedy remixing of the
products of differentiation in the column. Hence, in such hot
vents as those at Kilauea, Mokuaweoweo, or Matavanu, outflows
of highly differentiated lavas are not to be expected.

When Mauna Kea was approaching extinction, its magmatic
column or columns, characterized by increasing viscosity and
perhaps less charged with juvenile gases, were less stirred by
two-phase convection. In relative quiet they differentiated to
a slight extent, giving a trachydoleritic type as the upper, salic
pole. The gases became dissipated at the craters, and the
effluent lavas of this latest phase of the volcanic pile are
‘‘clinkstones’? because comparatively free of gas-pores. The
explosions which formed numerous cinder-cones at the summit
may have been due to the inhibition and superheating of meteoric

312 REGINALD A. DALY

water, as well as to the latest, violent expulsion of the juvenile
gases from the increasingly viscous magma.

Little is known of the detailed geology of the Kohala district,
but the abundance of cinder-cones on the heights of this other
great pile suggest a differentiation history resembling that sketched
for Mauna Kea. However, the strongly alkaline “andesite” of
Waimea, like the phonolitic trachyte of Puu Anahulu, may repre-
sent limestone-fluxing as a leading condition for such specially
advanced differentiation of the basaltic magma.

Parallel differentiation in other oceanic tslands.—Weber’s recent
study of the Samoan lavas, including those from Savaii, shows a
remarkable similarity between them and the rocks of the Hawaiian
group. The types already found in Savaii and in the neighbor-
ing islands include: olivine basalt, olivine-poor basalt, andesitic
basalt, trachydolerite, ‘‘Alkalitrachyt,” trachyte, and phonolite.
‘“Savaii”’ is said to be the Samoan equivalent of the name “ Hawaii.”’
By a curious coincidence the vent of Matavanu is, among vents
now active, the most perfect known analogue to Kilauea; and the
volcanic mechanism seems to be practically identical in these two
archipelagoes. The writer entirely agrees with Weber as to the
necessity of regarding the subalkaline and alkaline rocks of each
island group as syngenetic. The parallelism in the magmatic
histories of Savaii and Hawaii is shown even in details, for Weber
described olivine-augite nodules in the feldspar basalt of Mauga
Loa, a rock which in all respects recalls the nodule-bearing, ande-
sitic basalt of Mauna Kea.

Among the leading effusive types in Tahiti are olivine basalt,
olivine-free basalt, haiitynophyre, phonolite, and picrite, the
description of the last-mentioned rock resembling that of the ana-
lyzed 1852 flow in Hawaii. Although basalts compose most of
Tahiti, this mid-Pacific island has also furnished nephelite syenites,
theralites, essexitic gabbros, and tinguaites.2 In the Solomon
islands olivine basalt and augite andesite are associated with an

tM. Weber, Abhandlungen Math-phys. Klasse, Kgl. Bayerischen Akademie der
Wissenschaften, XXIV (1909), 287.

2A. Lacroix, Bulletin Société géologique France, X (1910), 91-124.

MAGMATIC DIFFERENTIATION IN HAWAII 22

augite trachyte which is suggestively like the phonolitic trachyte
of Puu Anahulu in Hawaii."

Reconnaissances in Kerguelen Island show the intimate asso-
ciation of olivine basalt, basalt bearing olivine nodules, trachyte,
and phonolite. Basalts and alkaline trachytes are the known
species composing Ascension Island. St. Helena shows dominant
olivine basalt and olivine-free basalt, with haiiynite basalt and
phonolite.

Without citing other parallels among the oceanic islands, it is
now clear that the repeated association of volcanic species, ranging
from olivine basalt to phonolitic trachyte or true phonolite, is not
accidental. In all essential respects the argument for the gravi-
tative differentiation of the salic types from normal basalt seems
as strong for the chief Samoan island as it is for the chief Hawaiian
island. It is commonly assumed that the subalkaline basalt
and the alkaline phonolite originate in separate primary magma
chambers. That hypothesis becomes almost, if not quite, incred-
ible to any unprejudiced observer of the imposing likeness in the
evolution of these distant, deep-sea island groups.

SUMMARY AND CONCLUSIONS

The writer’s 1909 traverses in Hawaii have led to the view that
the average of the many extant, typical analyses of its basalts
approximates very closely the composition of the real average of
all the basalt exposed in the island. This average is almost
identical with that calculated for the world’s average basalt.
While Mauna Loa and Hualalai are basaltic from base to summit,
Mauna Kea is, in a sense, stratified. Up to about the 6,o00-foot
contour, the broad basal slopes of Mauna Kea are underlain by
the normal olivine basalt. From that contour to the summit
platform, about 6,000 feet higher, the dominant lava is a basalt,
very poor in olivine and, in other respects also, approaching the
composition of a basic augite andesite. At the top of the moun-
tain are flows and cinder-cones largely consisting of a still less
femic type, in which alkaline feldspar (orthoclase or soda-

IW. W. Watts, Geological Magazine, XXIII (1806), 358.

314 REGINALD A. DALY

orthoclase) seems often to form an essential constituent. This
type is best classed as a trachydolerite of basaltic affinities. Its
chemical analysis is almost identical with that of a common phase
of the andesitic basalt, but, for some reason, alkaline feldspar
did not crystallize from the latter magma. This arrangement of
rock-species in Mauna Kea is explained as due to gravitative
differentiation in the normal basaltic magma.

More pronounced splitting is registered in the highly alkaline
trachydolerites and phonolitic trachyte occurring in the Kohala
district and at Puu Anahulu and the neighboring Puu Waawaa.
The development of these extreme types is tentatively ascribed to
changes in the normal basalt by its solution of small quantities of
sedimentary limestone cut by the respective lava conduits. No
direct evidence for this hypothesis has been found; it is based
on facts derived from the field and chemical relations of alkaline
rocks throughout the world. Whether this hypothesis is correct
or not, there can be little doubt that the alkaline rocks of Hawaii,
Savali, and other islands are as truly connected in a genetic way
with the normal basalt, as ordinary aplite dikes are genetically
connected with their respective granite batholiths. Such an origin
for the Hawaiian alkaline rocks is rendered all the more probable
because of their small relative bulk, and because of the perfect
chemical transition which can now be shown between the normal
basalt and the most salic of the alkaline types.

Further, a study of the olivine-pyroxene-anorthite segregations
in the andesitic basalt and in the trachydolerite of Mauna Kea
actually illustrates a stage of the differentiation. These nodules
formed in the magma when its viscosity must have been enormous;
else they would have rushed down into the conduit to levels where
no summit eruption, of the small size represented in the flows and
cones at the top of Mauna Kea, could have brought the nodules up
again. It is almost certain that the settling-out of the olivine
and pyroxene material (in solid or liquid phases) must have taken
place at slightly higher temperatures, when the viscosity was
much less. The residual magma must obviously become more
alkaline in proportion to the degree of settling-out.

The ultra-femic material, sinking to great depth, where it

MAGMATIC DIFFERENTIATION IN HAWAII 205

mixes with the hot, normal basalt, is subject to extrusion through
lateral fissures which bring the deeper levels of the conduit into
communication with the surface. Such is the preferred explana-
tion for the ultra-femic olivine-basalt which emanated from Mauna
Loa in 1852, and for the wehrlitic porphyry composing the Uweka-
huna laccolith.

An explanation is offered for the apparently contradictory fact
that gravitative differentiation is little evident in the thoroughly
basaltic summit rocks of Mauna Loa and Hulalai, or in the material
of the active vent at Kilauea.

As a result of studies in this and other fields, and in the general
literature of petrology, the writer is inclined to the belief that all
late pre-Cambrian and younger “alkaline”’ rocks are the result
of differentiation within primary basaltic magma or within syn-
tectic magmas formed by the solution of solid, generally sedi-
mentary, rock in the primary basalt. The marvelously uniform
composition of the basaltic magma issuing from countless fissures
in every ocean basin as in every continental plateau, seems capable
of explanation only on the premise that it forms the material of a
continuous, world-circling substratum. The facts of geology
suggest that this substratum was formed by an ancient liquation
which took place when the globe was molten at its surface. This
general conception became gradually clear to the writer during
the genetic study of many intrusive bodies; it had been visualized
in much the same form by that extraordinarily suggestive observer
of the Hawaiian volcanoes, W. L. Green, whose Vestiges of the
Molten Globe, Part II, first became known to the present writer
in 1909. Nota single one of the myriad facts recorded in general
petrography and geology definitely opposes this hypothesis, which,
to the writer, seems to be the best working premise for a general
philosophy of the igneous rocks.

Lastly, it appears from the accumulating results of geological
work that the division of igneous rocks into “Atlantic” and
“Pacific” races or groups is not warranted by the facts of distri-
bution, nor by the requirements of sound petrogenic theory, nor
by the needs of systematic petrography. In the heart of the
Pacific basin, as in many regions along its borders, rocks of foyaitic,

210. REGINALD A. DALY

theralitic, or other alkaline habit are already known, and the
number of occurrences in that part of the earth is constantly
growing. It may be quite true that alkaline rocks are more
abundant on the Atlantic side of the globe—possibly because thick
prisms of calcareous sediments are, in proportion to area, more
developed in the Atlantic region—but it is yet more apparent that
the overwhelming mass of the igneous rocks in the Atlantic region
are subalkaline in type. The distinction of the two “Atlantic and
Pacific races”? (Sippen) is not only fallacious in the literal, geo-
graphic sense; it introduces an unnecessary pair of terms of quite
elusive definition in place of the well-established, less nebulous
terms ‘“‘alkaline”’ and ‘‘subalkaline.”’ The proved difficulty of
making a clean-cut definition of the expression “‘alkaline rock”’ finds
explanation in the theory that all late pre-Cambrian and younger
alkaline rocks are of secondary origin, because derived from basalt
or from its syntectics. According to this view, many transi-
tional types should be found between the highly alkaline species
and those low in alkalies; iron-clad definition becomes impossible.

PETROGRAPHIC TERMS FOR FIELD USE

ALBERT JOHANNSEN
The University of Chicago

Velut aegri somnia, vanae
Finguntur species, ut nec pes nec caput uni
Reddatur formae.
—Horace, De arte poetica, 7.

Horace wrote this stanza with no idea of how aptly it would
apply to the megascopic classifications of rocks in use at the
beginning of the twentieth century. When the estimable authors
of the Quantitative System appended a field classification to their
system, they recognized the impossibility of accurately deter-
mining rocks megascopically, and said:

It is obvious that a considerable part of the system of classification and
nomenclature here proposed can only be applied upon microscopical or chemi-
cal investigation. .... For these reasons . . . . we are convinced of the
need of general petrographical terms, which will be serviceable in the field work
of the petrologist, and which will be of use to the general geologist and to
those who may not be able to carry on microscopical and chemical investi-
gations.

The authors proposed to select, from the terms originally given
by the geologists of the past, certain rock names and to give to
them their original significance “‘so far as possible, with only such
modifications as a somewhat more systematic treatment of the
matter may suggest.” The suggestion was truly commendable,
for the need of a field classification was seriously felt. Unfortu-
nately, perhaps, we are not living in the old days. The former rock
terms have, in the course of time, acquired new meanings, and
an attempt to revive the old ones produces much confusion.

Ut sylvae foliis pronos mutantur in annos,
Prima cadunt; ita verborum vetus interit aetas,
Et juvenum ritu florent modo nata vigentque.
—Horace, op. cit., 60.
And so it is with the old petrographic terms.
317

318 ALBERT JOHANNSEN

So far as the grouping of the rocks proposed by C. I. P. W.
is concerned, it is most admirable, and can hardly be improved
upon; it is only upon the rock terms chosen by them that any
criticism falls. .Teaching the names as selected, it is necessary
to impress upon the student that these are only indefinite field
terms—and he immediately wants to know the more exact defini-
tions. The student who later takes up microscopical work finds
—at the present time when the older systems must still be taught,
even if supplementary to the newer—that these definitions pro-
duce confusion, and he must either ‘“‘unlearn”’ the field terms or
else originally he must have learned the more exact usage as well.
The objection to the latter method is that it makes double work
for those students who want only a general megascopic knowledge
of the rocks. Had some simple change been made by the authors
of the Quantitative System, either in the words used or in their
endings, this difficulty would have been overcome. The following
substitutes are proposed as expressing, more or less, the fact that
the general type of rock represented by the original name is the
one preponderating in the group, and for this reason the suffix
-eid (from eidos, ‘form, appearance”) was chosen. As a matter
of fact the change proposed is not so great as the spelling would
suggest. It is only a change in the pronunciation produced by
the substitution of a single letter—from granite to granide, syenite
to syenide, etc. The object in using -e7d instead of -ide is twofold.
It conforms to the derivation of the word, and in those countries
where the final e is omitted, the ending ide, changed to zd, has the
short sound; -e7d is everywhere pronounced the same. It will be
noted that some of the C. I. P. W. terms are retained, for to such
words as phanerite and aphanite there are no objections. For
uniformity, however, the same ending is used below in these forms
as in the others.

As divided by the authors of the Quantitative System, so here
also the rocks are divided into three main divisions.

I. Phanereids (pavepos, “visible,” and ¢tdos, ‘‘form”’). Rocks
whose different constituents can be seen megascopically.

II. Aphaneids (abavys, “unseen,” and ¢d0s), Rocks which
contain a greater or lesser amount of megascopically indetermi-
nable components. These are subdivided into

PETROGRAPHIC TERMS FOR FIELD USE 319

a) Aphaneids, properly so called. Non-porphyritic.

b) Aphaneid porphyries. Porphyritic rocks with aphanitic
groundmasses. For consistency some other word should be
substituted for porphyry, since this term is generally applied only
to orthoclase rocks, and by some writers to rocks with two genera-
tions of minerals, with or without phenocrysts. The term, however,
is In such general use among miners and quarrymen, and by the
U.S. Geological Survey, for all rocks containing larger crystals in
a fine-grained or dense ground-mass, that it may be better to retain
it. Poikileid (qovxdos, “spotted,” and eos) would be much
better.

III. Glasses. Rocks which are hyaline or which have hyaline
ground-masses.

On the basis of mineral composition, the rocks can be divided
megascopically most easily into those that are light and those
that are dark. Consequently the groups are divided into those
in which |

1. Femag™ minerals form less than half the rock.

2. Femag minerals form over half the rock.

3. Light-colored minerals absent or nearly so.

While it is generally impossible to separate different feldspars
megascopically, quartz can usually be recognized. Its presence
or absence is therefore made the basis of a further subdivision, as
is also the presence or absence of olivine in the no-feldspar rocks.

It has been found possible to subdivide the rocks megascopically
into the following groups:

I. PHANEREIDS

Graneid.—A holocrystalline, medium- to coarse-grained igneous
rock, consisting of quartz and any kind of feldspar, with one or
more members of the biopyribole group,? generally biotite or —
hornblende. The femag minerals form less than 50 per cent of

t The term femic has been used repeatedly by recent writers as synonymous with

ferro-magnesian. This is incorrect, since femic minerals include apatite, fluorite,
calcite, etc. The term femag is here used for ferro-magnesian.

? Biopyribole is suggested as a substitute for the awkward words biotite } ne
pyroxene ane amphibole, and pyribole for pyroxene rie amphibole.

320 ALBERT JOHANNSEN

the rock. Under this term are included all granites, and the light-
colored quartz diorites.

Syeneid.—A holocrystalline, medium- to coarse-grained igneous
rock, consisting of one or more kinds of feldspar and one or more
members of the biopyribole group, generally biotite or hornblende.
The femag minerals form less than 50 per cent of the rock. Under
this term are included syenites, nephelite syenites, and the light-
colored diorites.

There is a slight objection to this term in that the pronunciation
is the same as cyanide. Sinai-eid (the rock at Sinai being a true
syenite) might be used except for the superabundance of vowels.
Esseneid or Assuaneid, from the modern names for Syene, are also
suggested, but on the whole, on account of the common use of
the term syenite, it seems best to retain syeneid.

Dioreid.—A holocrystalline, medium- to coarse-grained igneous
rock in which the femag mineral is an amphibole and forms over
half the constituents. Feldspar, of any kind, is subordinate in
amount. To this group belong the shonkinites, the dark-colored
diorites, and the hornblende gabbros.

Quartz dioreid is a subgroup.

Gabbreid.—A holocrystalline, medium- to coarse-grained igneous
rock in which the femag mineral is pyroxene and forms over 50
per cent. Feldspar, of any kind, is subordinate in amount. Here
are included the augite diorites, gabbros, and norites.

Quartz gabbreid is a subgroup.

Dolereid.—It is usually impossible to determine, megascopically,
the species of pyribole present. In such cases the term dolereid
may be used instead of dioreid or gabbreid.

Quartz dolereid is a subgroup.

Pyroxeneid.—A holocrystalline, medium- to coarse-grained ig-
neous rock which consists almost entirely of pyroxene. The term
covers the rocks now called pyroxenites.

Amphiboleid.—A_holocrystalline, medium- to coarse-grained
igneous rock which consists almost entirely of amphibole. It
includes igneous hornblende rocks, whether the hornblende is
primary or secondary.

Pyriboleid.—A_ holocrystalline, medium- to coarse-grained ig-

PETROGRAPHIC TERMS FOR FIELD USE 321

neous rock, consisting almost entirely of one or more members
of the pyribole group. It includes the pyroxeneids and amphibo-
leids, and corresponds to dolereid among the feldspar rocks.

Peridoteid.—A_ holocrystalline, medium- to coarse-grained ig-
neous rock, consisting of olivine, with or without pyriboles. Feld-
spar is absent. ‘This group includes the peridotites.

II. APHANEIDS

Felseid.—An aphanitic igneous rock, non-porphyritic and light-
colored. Here are included non-porphyritic rhyolites, trachytes,
phonolites, latites, and the light-colored andesites. They are Jeuco-
aphaneids (AeEvKos, ‘“white’’).

Felseid porphyry.—Under this head are grouped all light-colored
porphyritic igneous rocks with aphanitic ground-masses. They
may also be called leucophyreids.

Quartz felseid porphyries or quartz leucophyreids are those
felseid porphyries among whose phenocrysts quartz can be recog-
nized. Other mineral modifiers, such as orthoclase, biotite, horn-
blende, etc., may be used for different varieties.

Anameseid.—An aphanitic igneous rock, non-porphyritic and
dark colored, generally dark gray, dark green, dark brown, or
black. In this group are included the dark andesites and basalts.
They are melano-aphaneids (weravos, “dark’’).

No sharp line can be drawn between these rocks and the fel-
seids. The relative amounts of the dark and the light con-
stituents cannot be determined megascopically, and it is only
possible to classify the felseids by their colors, which are white,
yellow, light brown, pink, and pale gray.

Basalt, being such an overworked word, von Leonhard’s term
anamesite was chosen instead as the root. It was originally applied
to basaltic rocks of such fine texture that the constituents were
indistinguishable megascopically.

Anameseid porphyry.—In this group belong all dark-colored
porphyritic igneous rocks with aphanitic ground-masses. The
term melanophyreid may also be used. If the phenocrysts can be
determined, their names may be prefixed, as biotite melanophyreid
or biotite anameseid porphyry, etc.

ALBERT JOHANNSEN

Il.

GLASSES

Since the glasses can be determined megascopically as such,
the usual terms are retained, as pumice, obsidian, pitchstone, etc.
For the porphyritic glasses the term vitrophyreids is proposed.

Tabulating these terms:

Such a classification can be learned by a student in ten minutes.
The rocks are subdivided into as many groups as can be recog-
nized megascopically, and unknown specimens classified by differ-
ent persons will almost invariably be found to fall into the same

groups.

Frankly acknowledging, by the names used, the field

character of the determinations, there will be no confusion caused
if later more exact terms are applied to the same rocks.

THE EVOLUTION OF LIMESTONE AND DOLOMITE. I

EDWARD STEIDTMANN ©
University of Wisconsin

CONTENTS
INTRODUCTION

Part I. THe EVMENCE ON THE ORIGIN OF DOLOMITE

A. The evidence for the origin of dolomite in the sea.
Interstratification of limestones, magnesian limestones, and dolomites,
the result of primary conditions of sedimentation, or of the differential
metamorphism of limestones after their emergence from the sea.
Fineness of grain peculiar to some dolomites, probably indicative of
very little metamorphism since deposition.

Many dolomite formations lack fossils.

Association of certain dolomites with gypsum and salt deposits.
Chemical precipitation of dolomites in the sea.

Experimental evidence for the chemical precipitation of dolomite.
Daly’s hypothesis of direct precipitation of dolomite in primitive ocean.
Deposition of magnesian limestones by marine organisms.
Development of magnesium limestones and dolomites by marine
leaching.

The origin of dolomite by the secondary replacement of calcium by
magnesium in the sea.

Experimental evidence on the origin of dolomite by secondary replace-
ment of calcium chloride.

B. The evidences for the origin of dolomite by the metamorphism of
limestones after their emergence from the sea.

Direct chemical precipitation of dolomite.

Origin of dolomite by leaching limestones after their emergence
from the sea.

Origin of dolomite by secondary replacement of limestone.

C. Evolution versus the metamorphism of limestones after their emer-
gence from the sea as explanation for the increase in the ratio of
calcium to magnesium of limestones and dolomites with geologic time.

WHat Factors CONTROLLING THE DEPOSITION OF CALCAREOUS MARINE

Deposits HAVE UNDERGONE A GRADUAL EVOLUTION RESULTING IN THE

EVOLUTION OF THE LIMESTONES AND DOLOMITES ?

Part IJ. Catctum AND MAGNESIUM IN THE PRopuUCTS OF METAMORPHISM
Materials lost by the weathering of acid igneous rocks.

Materials lost by the weathering of basic igneous rocks.

Materials lost by the weathering of limestones.

Résumé of the materials lost by weathering.

Materials lost by dynamic metamorphism

Materials lost by contact metamorphism.

Materials lost by hot solution.

Résumé of calcium and magnesium in the products of metamorphism.

323

324 EDWARD STEIDTMANN

Has SEDIMENTATION INCREASED THE RATIO OF CALCIUM TO MAGNESIUM OF

THE LANDS DURING GEOLOGIC TIME ?

The geologic record of the continental interiors.

The geologic record of the continental margins.

Deposition within the too-fathom line.

Deposition beyond the roo-fathom line.

Significance of the deposition of muds in the ocean basins.

Does the ratio of calcium to magnesium in the sea show a selective loss
of magnesium from the lands with geologic time?

Résumé of the results of sedimentation and their effect on the ratio of
calcium to magnesium of the lands.

HAS THE RATIO OF CALCIUM TO MAGNESIUM IN THE RIVER WATERS INCREASED

WITH GEOLOGIC TIME ?

Influence of the terranes on the calcium-magnesium ratio of underground
waters and streams.

The influence of climate on the calcium-magnesium ratio of streams.
Influence of the belt of cementation on the calcium-magnesium ratio of
underground waters.

Average calcium-magnesium ratio of the solutions contributed to the sea.
Conclusion: Increase of the ratio of calcium to magnesium in rivers with
geologic time.

STATEMENT OF HYPOTHESIS
SUMMARY

INTRODUCTION

Many writers' have called attention to the decrease in the

percentage of dolomite in going up the geologic time scale, and

« Daly has shown the decrease in dolomite with age in the following compilation

of analyses (Table I, from Bull. Geol. Soc. Am., XX, 165):

TABLE I
AVERAGE Ratio oF CatcrumM TO MAGNESIUM IN LIMESTONES OF DIFFERENT PERIODS
I 2 B
Period Number of - Ratio of CaCO; Ratio of Ca to
Analyses to MgCO; Mg
Pre-Cambrian:
a) From North America, except those
bE) es Pes en pe ar in ee 28 I.64:1 2E30n1
6) From Ontario (Miller)............ 33 4.92:1 6.89:1
c)wAverage ofa) iand0)\\.c,c1s eile terete Or 2:93:1 4.10:1
d) Best general average............. 40 2.58:1 3.01:1
Cambrian (including 17 of the Shenan-
doahilimestone)iceaaeessoe este 30 2.960:1 AwkAwL
Ordovician terre sclrmie rai ta 93 Qi wait 3.8I:1
Silurianye eee a censor ere 208 2.09:1 2.93:1
Allepre=Devonianeny-ceiee ees 3092 2.39:1 Se Soe
Devonian aactere sectthationis steve scayeee eeteele : 106 4.49:1 6.29:1
Carboniferous. . . 238 8.809:1 I2.45:1
Cretaceous. e:3- 27. erenees1> Are 77 40.23:1 56.32:1
Mertiarys iss ss eR ee eee Corie 26 SO 240 53-00:1
Quaternary and Recent 20 25.00:1 35.00:1
Potalss, 2 reastotsarnt ok cloe eens 865

EVOLUTION OF LIMESTONE AND DOLOMITE 325

various hypotheses have been offered for its explanation. Probably
the majority of geologists hold that it is due to a secondary altera-
tion of limestone to dolomite, which is roughly proportional to
time. Dalyt has suggested that it is due to a change in the nature
of the life processes which effect the precipitation of carbonates
in the sea. Still another alternative hypothesis is herewith offered,
that the percentage of dolomite developed in the sea has declined
with time, and that this was controlled by a progressive increase in
the ratio of calcium to magnesium contributed from the lands.

Absolute proof for any one of these hypotheses is impossible
from the very nature of the problem. For instance, all of them are
based on the theory of uniformitarianism, a theory deep rooted
in geologic evidence, but a theory nevertheless. All the hypotheses
offered involve the question of whether dolomite develops pre-
dominantly in the sea, regardless of the specific processes of for-
mation, or whether it is predominantly a secondary product from
limestones, after their emergence from the sea. If its origin is
mainly in the sea, which of the factors controlling deposition in
the sea has changed so as to cause a decline in its deposition with
time? Was it temperature, pressure, life processes, the chemical
composition of the sea, or some combination of these factors?
To these no final answer can be made. The available evidence
for each view can be sifted. Conclusions may be drawn, but the
probability may be freely recognized that in the future some of
the conclusions may become invalidated.

PART I. THE EVIDENCE ON THE ORIGIN OF DOLOMITE

That the predominance of dolomite in the ancient sediments is due
in a larger measure to primary conditions of deposition in the sea than
to the metamorphism of limestones after their emergence from the
sea seems to follow from a comparison of the evidence on the origin
of dolomite in the sea with that on the origin of dolomite by the
metamorphism of limestone after its emergence from the sea.

A. THE EVIDENCE FOR THE ORIGIN OF DOLOMITE IN THE SEA

Interstratification of limestones, magnesian limestones, and dolo-
mites the result of primary conditions of sedimentation, or of the

t [bid.

326 EDWARD STEIDTMANN

differential metamorphism of limestones after their emergence from
the sea.—In a succession of conformable formations, each forma-
tion usually presents a certain specific lithologic unity of character
which is different from that of adjacent formations, and may or
may not be related to them by gradation phases. Thus limestones
are not infrequently sharply interstratified with dolomites, and
give by their color contrasts a graphic portrayal of the sharp
lithologic difference which frequently distinguishes adjacent
carbonate formations. Attention is directed to a number of
typical illustrations of sharply defined stratigraphic cleavage
between limestones and dolomites. The “lead and zinc”’ district
of southwestern Wisconsin presents the following interesting
succession :

System Formation PY eTAES, ie Lithological Character, etc.
Hudson
River 160 Shale.
Galena 250 Dolomite. Limestone layers, sharply
interstratified near bottom.
Containing |
oil rock 3+ Oily shale, not deposited everywhere.
Ordovician |
| Clay 3+ | Not deposited everywhere.
| Glassrock 3+ | Sharply defined limestone. Very pure.
Platteville 55 | Magnesian limestone and dolomite.

A striking case of sharp interstratification of nearly pure lime-
stone beds and dolomites is described by F. B. Peck* as occurring
in the Trenton of Lehigh and Northhampton counties, Pa.

I. P. Lesley’s? study of the Cambro-Silurian limestones of Cum-
berland County, Pennsylvania, is perhaps the most detailed
quantitative chemical study of a limestone section which has ever
‘been made from the viewpoint of throwing light on the origin of
limestone and dolomite. The section studied was about 375 feet

F, B. Peck, Eco. Geol., III, No. 1, p. 43.
27. P. Lesley, Second Geol. Survey Pa., Vol. MM (1897), pp. 311-62.

EVOLUTION OF LIMESTONE AND DOLOMITE BAG)

thick, consisting of conformable, uniformly dense, slightly dis-
turbed beds of limestone sharply interstratified with beds of
magnesian limestone and dolomite. Analyses taken from various
parts of each bed showed that each bed constituted a lithologic
unit which often differed sharply from adjacent beds.

To E. Suess,t the sharply defined, thin-bedded intercalations
of limestone and dolomite in the Plattenkalk present such powerful
evidence of characters which could not have been acquired by
metamorphism after their emergence from the sea, that he regards
them as direct chemical precipitates. While it may be difficult
to agree with Suess that chemical precipitation, in cases like that
of the Plattenkalk, is proven, there certainly can be no doubt
that it is easier to conceive of such formations as being the direct
result of sedimentary processes in the sea, than to believe them to
be the result of the differential metamorphism of limestone beds
after their emergence from the sea. It is difficult to see how the
metamorphism of a succession of conformable limestone beds or
formations after their emergence from the sea could be so thor-
oughly selective as to result in a succession of beds or formations
of unlike composition. Circulating underground water, the most
universal agent of the alternation of sediments after their emergence
from the sea, is obviously most effective along joints, bedding
planes, or other large openings both parallel to and across the
bedding, the so-called “trunk channels of circulation” repeatedly
emphasized by Van Hise in his‘ Treatise on Metamorphism.’”

Until more direct evidence has been submitted for the origin
of dolomite formations through circulating underground water,
it seems more reasonable to assume that interstratifications of
dolomite and limestone result from primary conditions of sedi-
mentation, regardless of what the specific processes of limestone
and dolomite building may have been.

Fineness of grain, peculiar to some dolomites, probably indicative
of very little metamorphism since deposition.—Attention is directed
to the fineness of grain which some dolomites possess. Daly?

1K. Suess, The Face of the Earth, I, 262.

27R. A. Daly, “The Evolution of the Limestones,” Bull. Geol. Soc. of America,
XX (1909), 167-68.

328 EDWARD STEIDTMANN

finds that the slightly disturbed dolomites of Cambrian and pre-
Cambrian age of the forty-ninth parallel section of the Rocky
Mountain geosynclinal, aggregating about 7,000 feet in thickness,
are singularly monotonous in their fineness of grain, averaging
about 0.02 millimeter. Other fine-grained and similarly undis-
turbed dolomites mentioned by Daly are those of the Archean
at the headwaters of the Priest River, Idaho, the magnesian
limestones and dolomites inclosing the chitinous fossil Beltina
donai in the Clarke range and the Siyeh and Sheppard siliceous
limestones of northwestern Montana, probably of middle Cambrian
age. He also quotes Vogt as stating that the finest grained Nor-
wegian dolomites average from 0.02 to 0.03 millimeter in diameter.

Willis and Blackwelder in their studies of the geology of China
for the Carnegie Institution describe a number of very fine-grained,
dense dolomites of considerable extent and thickness.

The pre-Cambrian dolomite formation of the Baraboo™ syn-
clinal is singularly fine grained. The Niagara limestone of Wis-
consin, a dolomitic formation, is generally a very even-textured,
fine-grained, and compact rock.

The generalization may be deduced from the facts cited that
many undisturbed or only slightly disturbed dolomites are exceed-
ingly fine grained and compact. There does not appear to be any
evidence that this fineness of grain is the result of granulation.
Furthermore, the relative mobility and regenerative power of the
carbonates is very great as compared with the other minerals.
Coarse-grained, even-textured? marbles showing no strain effects
are found interbedded with banded gneisses with marked strain
effects. Unless conditions are peculiarly unfavorable for recrystal-
lization, the metamorphism of dolomites would probably result
in coarser grain. The fineness of grain and compactness of many
dolomites may therefore be interpreted as showing that they were
dolomite before they emerged from the sea.

Many dolomite formations lack fossils—The opinion is reflected
from geologic literature that fossils are less common in dolomite

1S. Weidman, “Baraboo Iron-bearing District,” Wisconsin Survey Bull., No. 13
(1904), p. 67.
2C. R. Van Hise, ‘‘Treatise on Metamorphism,” U.S.G.S. Mon. 47, p. 738.

EVOLUTION OF LIMESTONE AND DOLOMITE 329

than in limestone, although no quantitative study of this problem
seems to have been made. It has been observed in various places
that the limestone beds intercalated between dolomite are full
of fossils, while the dolomite is barren. Illustrations of this are
found in the Galena limestone of Wisconsin. The paucity of fossils
in dolomites has been variously interpreted, some holding that
fossils were never present in the formation because the conditions
at the time of deposition were unfavorable to life, while others
claim that they were originally present but have been destroyed
by metamorphism. In connection with the first interpretation,
it is interesting to note that magnesium-bearing solutions have
actually been found to be unfavorable to life processes. It may be
the correct interpretation in the case of certain dense, fine-grained
dolomites. On the other hand, porous, cavernous dolomites like
the Lower Magnesian of the Upper Mississippi valley, which is
nearly devoid of fossils, evidently has undergone considerable
recrystallization which may have destroyed the fossil record.
No final conclusion seems to follow from the apparent fossil bar-
renness of dolomites with reference to the origin of dolomite.

Association of certain dolomites with gypsum and salt deposits. —
Of certain dolomites which are found with deposits of salt, gypsum,
and red beds and other indications of aridity and concentrated
seas, It has been suggested that they are direct chemical precipi-
_ tates, since conditions of deposition were apparently unfavorable
to life. This view is open to the criticism that no case is known
where this process is in operation at the present time. However,
regardless of what the specific processes of dolomite building were,
it seems more likely that these deposits were primarily dolomite
because gypsum tends to decompose dolomite into calcium car-
bonate and magnesium sulphate. Therefore, if any alteration of
the deposit had taken place since deposition, it would seem more
likely to result in the decomposition of dolomite than in dolomiti-
zation.

Chemical precipitation of dolomite in the sea.—Crystals of dolo-
mite grow in vugs and cavernous openings of coral reefs in the
Pacific Ocean, according to E. W. Skeats.*

tE. W. Skeats, Bull. Mus. Comp. Zoél., XLII (1903), 53-126.

330 EDWARD STEIDTMANN

Experimental evidence for the chemical precipitation of dolomite.—
The direct precipitation of dolomite from solution has apparently
not been done, experimentally. Sterry Hunt" precipitated cal-
cium carbonate and the hydrous carbonate of magnesium with
sodium carbonate and found that he could develop dolomite by
heating this mixture to 120° C.-130° C. Obviously this experiment
did not accomplish direct chemical precipitation of dolomite nor
is it applicable to the explanation of the majority of dolomites in
nature.

Daly’s hypothesis of the direct precipitation of dolomite in the
primitive ocean.—Daly* postulates that dolomite was precipitated
from a nearly limeless primitive ocean by ammonium carbonate
generated by the decay of organisms on the bottom of the ocean.
The hypothesis is based on several assumptions, namely: (a)
the scavenging system of the pre-Cambrian and the early Paleozoic
ocean was less perfect than at present; (b) the post-Huronian
uplift gave a tremendous impetus to the transportation of lime
to the sea, which in turn stimulated the development of lime-
secreting organisms; (c) the improvement of the scavenging
system and the development of lime-secreting organisms gradually
brought the balance in favor of the deposition of limestones by
organic secretions over direct chemical precipitation. The theory
is offered to explain a number of facts: (a) the predominance of
dolomite in the older formations; (6) characteristics such as grain,
fossil record, and field relations of certain dolomites indicative of
direct chemical precipitation; and (c) the apparent similarity
between the ratio of calcium to magnesium in the older dolomites
and the ratio of calcium to magnesium of streams on pre-Cambrian
crystalline terranes. This theory fits many facts remarkably well.
However, the premises on which it is based are open to objection.

It is true that the decay of marine organisms generates? ammo-
nium carbonate and other precipitants. But organic decay also
generates carbonic acid, which tends to keep the carbonates of

« Sterry Hunt, Chem. and Geol. Essays (1895), 80.

2R. A. Daly, ‘First Calcareous Fossils and the Evolution of the Limestones,”’
Bull. Geol. Soc. of America, XX, 153-70.

3G. Steinmann, Ber. Naturforsch. Gesell. Freiburg, TV (1889), 288; Challenger,
Report on Deep Seas, 255.

EVOLUTION OF LIMESTONE AND DOLOMITE 23a

lime and magnesia in solution. The rapid corrosion of marine
shells is partly ascribed to this agency, by the authors of the
Challenger deep-sea report. Thomson’s' observations that the
local abundance of carbonic acid on the ocean bottom is associated
with an abundance of organisms is suggestive. Corrosion of
calcareous remains by the direct action of sea water, but pre-
dominantly by the action of carbonic acid resulting from organic
decay, is regarded by Murray as sufficiently powerful to prevent
the accumulation of calcareous ooze at a mean depth of 2,730
fathoms, over 51,500,000 square miles of ocean bottom, the Red
Clay area.

It therefore seems to be an open question whether the net
chemical effect resulting from organic decay in the ocean is pre-
cipitation or corrosion. The scavengers of the present ocean do
not arrest the accumulation of calcareous oozes over millions of
square miles of the ocean bottom. The evidence that direct pre-
cipitation of calcium carbonate is taking place on those vast areas
of organic decay is doubtful. Philippi,? viewing direct chemical
precipitation as an important process in the origin of limestones,
after citing the data offered by various investigators for direct
chemical precipitation from the present ocean, concludes that
certain incrustations and the cements of some oozes are probably
chemical precipitates. He believes that warm seas, teeming with
life, where decay on the bottom is rapid are favorable localities
for the precipitation of calcium carbonate.

The acquisition of the lime-secreting habit by marine organisms
in response to an accumulation of lime in the ocean postulated as
a result of the post-Huronian erosion cycle, and the increase in
scavengers may be possible. Paleontologists believe that at least
nine-tenths of the organic evolution into main stocks was accom-
plished before the Cambrian. The Cambrian record contains
evidence for the existence of all phyla excepting the vertebrates,
and the unsuccessful search for vertebrate fossils in the Cambrian
cannot be regarded as conclusive evidence for their absence. The
burden of proof, therefore, rests heavily on any theory based on

C. Wyville Thomson, Depths of the Sea, 502-11.
2 Philippi, Newes Jahrb. (1907), 444.

232 EDWARD STEIDTMANN

radical differences in the organic development of the early Paleozoic,
as compared with the present, and a correlative, fundamental
difference in the constitution of the ocean.

Nor would all students of the pre-Cambrian admit that the
profound importance which Daly attaches to the post-Huronian
erosion cycle is evident. It was preceded by at least three periods
of emergence in the Lake Superior and Lake Huron regions and in
Finland. So far as known, any one of them may have contributed
as much lime to the sea as the post-Huronian.

Deposition of magnesian. limestones by marine organisms.—
Marine organisms deposit magnesium carbonates in small quanti-
ties. According to G. Forchhammer,’ marine shells and corals
contain magnesium carbonate in varying amounts from o.15 to
7.64 per cent, 1 per cent being rather above the average. In
Lithothamnium nodosum, Giimbel? found 2.66 per cent of magne-
sium and 47.14 per cent lime, and Hégbom! in fourteen analyses
of algae belonging to this genus reports from 1.95 to 13.19 per
cent of magnesium carbonate.

The development of magnesium limestones and dolomites by marine
leaching.—It has been shown that marine leaching is very effective
in concentrating the magnesian content of limestone formations.
This is due to the fact that calcium carbonate is several times as
soluble as magnesium carbonate, as was first shown by Bischoff.
The decrease in calcium carbonate and the corresponding increase
in magnesium carbonate resulting from marine leaching is well
shown in the table on p. 333, compiled by G. Hogbom.4

Hoégbom’ washed the clay marl of Upsula with carbonated
water with the following results. The original composition of the
marl was calcium carbonate, 18 per cent, magnesium carbonate,
1.3 per cent. The loss of calcium carbonate was about 50 per
cent, while the loss of magnesium carbonate amounted to only a
trace.

In his studies of the marine marls of Sweden, Hégbom found

«1G. Forchhammer, Neues Jahrb. (1852), 854.

2 Quoted from Bull. 330, U.S.G.S., 485.

3 Hégbom, Newes Jahrb. I (1894), 262.

4 Ibid., 262-74. 5 [bid., 268.

EVOLUTION OF LIMESTONE AND DOLOMITE 233

that the transported material contained progressively larger
proportions of magnesium as its distance from the parent lime-
stone increased. Near its point of origin, the marl carried 3.7
parts of magnesium carbonate to too of calcium carbonate, and
from these figures the ratio was generally raised to 36 magnesium
carbonate and too calcium carbonate.

TABLE II

TABLE COMPUTED FROM 21 GLOBERGERINA, 21 RED Mups, 7 RADIOLARIAN OOZES,
PtTEROPOD OozE, Diatom OozE, AND BLuE Mup

CaCO; Limits CaCO; MgCO; Relative Values* Analysis
SO>TOOm- ania rk 86.7 17 8 8
GOnCOn Se: 68.3 Toa 2.0 8
MOADlo ako oy Gece ones TZ 24 8
NOMOss sa eu es 22), 9 3.0 3
TO—=2Op i ais oe 16.2 1.6 10.0 4

FlOddo oases 6.1 ay) Te I

Sy ren enar Bey 1.6 43.0 7

Te Serre eae 20 Zea 105.0 9

* Relative values express parts of MgCO;:100 parts of CaCQ;.

The stalactites from the caverns in the coral rocks of Bermuda,
according to Hégbom, contain only 0.18 to 0.68 per cent of mag-
nesium carbonate, while the rocks themselves carry about five
times as much magnesium carbonate. The lime salt has evidently
dissolved much more freely than the magnesium compound.
This mode of concentrating magnesium carbonate must, from
the evidence cited, be regarded as real, and may be instrumental
in causing the development of dolomite. It is obvious that the
smaller the content of calcium in the sea, as compared with mag-
nesium, that is, the smaller the relative quantity of calcium result-
ing from the difference between contribution from the land on the
one hand, and precipitation on the other, the more effective will
be the process of leaching. The precipitation of calcium carbonate
in the sea is now largely controlled by life processes, and probably
has been at least as far back as the beginning of the Paleozoic,
so that since Zoic times there has been a powerful agency at work,
tending to deplete the calcium content of the sea, while leaving
the soluble magnesium salts to accumulate. Solid phases. of
calcium carbonate are therefore farther removed from a condition

334 EDWARD STEIDTMANN

of equilibrium with sea water than the corresponding magnesium
salt. Aside, then, from the inherent difference between the
solubility of calcium carbonate and magnesium carbonate, the
chemistry of the sea apparently facilitates the solution of calcium
carbonate and retards that of magnesium carbonate. Assuming
that the efficiency of the organic precipitation of calcium carbonate
has been about the same throughout Zoic times, it seems obvious
that the concentration of magnesium carbonate in calcareous
deposits by marine leaching would have been even more effective
than now, if at some time in the past the rivers had contributed
relatively less lime and more magnesia than at present. If there
is any probability that such has actually been the case, that would
constitute one factor which would operate to cause an increase
in the magnesium content of limestone in descending the geologic
time scale.

The origin of dolomite by the secondary replacement of calcium
by magnesium in the sea.—Coral rocks originally contain only a
small percentage of magnesium carbonate, usually less than 1
per cent. In 1843, J. D. Dana’ in a rock from the coral island
of Makatea, in the Pacific, reported magnesium carbonate to the.
extent of 38.07 per cent. This approached the dolomite ratio
which requires 45.7 per cent, and it was suggested that the rock
had been dolomitized through secondary replacement, the mag-
nesium carbonate probably having been derived from the concen-
tration of shallow lagoons of sea water. Since Dana’s time, many
other investigators have recorded similar enrichments of coral
reefs. In acoral reef from Porta do Mangue, Brazil, T. C. Branner?
reports 6.95 per cent of magnesia, equivalent to 14.6 of carbonate,
while the corals themselves contained only 0.20 to 0.99 per cent
of magnesia. E. W. Skeats’ reports analyses of dolomitic coral
rock of the Pacific in which the magnesium carbonate rises to a
maximum of 43.3 per cent.

The borings from the atoll of Funafuti as discussed by J. W.
Judd* present a remarkable case of transformation from reef

1J. D. Dana, Corals and Coral Islands (3d ed.), 393.

2T. C. Branner, Bull. Mus. Comp. Zodl., XLIV (1904), 264.

3E. W. Skeats, Bull. Mus. Comp. Zoil., XLII (1902), 53-126.

4J. W. Judd, The Atoll of Funafuti, quoted from Bull. 330, U.S.G.S., 487.

EVOLUTION OF LIMESTONE AND DOLOMITE

rock to dolomitic limestone.

$35

The principal boring was driven to

a depth of 1,100 feet, through coral and coral rock all the way,
and samples of the cores were analyzed every ten feet of the dis-
tance. The following table of data, quoted by Bull. 330, U.S.G.S.,
p. 487, shows first, an enrichment in magnesium carbonate near
the surface, then an irregular rising and falling in much smaller
amounts, while below 700 feet the rock approaches the dolomite

ratio.
TABLE III
MAaGNeEsIuM CARBONATE IN BORINGS ON ATOLL OF FUNAFUTI
Depth Feet Percentage MgCO; Depth Feet Rercen ee ene

Ais 6c Sidect Eien ete 4.23 205 3.6
TQ Rae O Lin sede east. TO 2 400 ect
TiS as Sea ea 16.40 500 DG
2 OWNeay ferme dabrtans) eit cavers I1.9Q 598 1.00
2 Oem peas aac tane anya 16.0 640 26.33
BGG acs een eee 5.85 698 40.04
TAU Opec Hrtey ees c aeons 2200 795 38.92
IEG) > cee cuiepesene ne eee eaten 0.79 898 39.99
DOOM Mea Meteo wich shea ah 2.70 1000 40.56
Ds OMe eal ore vine eliseoh2 4.9 III4 41.05

In the analyses of coral rock borings from an artesian well at
Key West, Florida, reported by George Steiger," there is no apparent
relation between the content of magnesia and depth as shown by
the borings on the atoll of Funafuti.

TABLE IV
LimME AND MAGNESIA IN BORINGS AT KEY WEST

|
|

P t g

Depth Feet Caos e
25 clo’ pet: peo 54.03
MOOR revere toads 54.01
MOO s.¢ oiet0 wae 54-38
BIOs co oa oOo 51 46
(Glog epee 48.87
775 foiesins)fiettelisimoiie 46.53
II25 Cho D Oeo arose 53-84

Percentage
MgO

- 29
77
86
67
50
70
86

ODnNHOAOO

Depth Feet

1325
1400
1475
1625
1850
2000

Percentage
CaO

54.49
Bente
54.48
53-90
54.28
54.02

Percentage
MgO

.62
30
73
14
S30)
ele)

ise On OO,

The dolomitization of organic calcareous deposits in the sea
by secondary replacement as well as by leaching seems to be too
well established to admit of serious doubt.

t George Steiger, Bull. 228, U.S.G.S. (1904), 300.

The degree of dolo-

336 EDWARD STEIDIMANN

mitization in any given case may be influenced slightly by the
original composition of the calcareous secretions: witness the
difference in the content of magnesium carbonate in secretions
from Lithothamnium and other members of this genus as compared
with those of the corals. Certain calcareous secretions have been
found to consist of calcite while others like those of the corals
consist largely of aragonite. Aragonite is much less stable than
calcite, hence the aragonite secretions are probably much more
subject to dolomitization through leaching and replacement than
the more stable form of calcium carbonate, calcite. Furthermore,
it is highly probable that the composition of the sea is an important
factor in dolomitization. If sea water is high in magnesium and
low in calcium, it is probable that the conditions are more favorable
for the dolomitization of calcareous deposits than if the reverse
condition prevailed, as may be inferred from the following experi-
ments. If a crystal of calcite is placed in water, solution will
take place until equilibrium is reached between the calcite and the
solution. Obviously, replacement, in the absence of magnesium
salts, cannot take place. On the other hand, Sorby found that a
crystal of calcite placed in a concentrated solution of magnesium
chloride became slowly incrusted with magnesium carbonate,
and Pfaff developed a dolomitic material by subjecting calcium
carbonate to the action of a solution of magnesium chloride or
sulphate and common salt, under pressure comparable to the deep
sea, in which case the speed of reaction was proportional to the
concentration of the solution.

It is obvious that 60 pounds of calcium carbonate could not be
replaced by a solution containing only to pounds of magnesium
salt in anything like the proportions required by the dolomite
ratio. It seems equally probable, a priori, that if the river waters
carried calcium and magnesium to the sea in the ratio of 1:1, the
chances for dolomitization through leaching, secondary replacement,
or possibly primary deposition would be better, all other things
being equal, than when the proportion of river-borne calcium to
magnesium is 6:1, which is the approximate ratio at the present
time according to the best estimate.’

t See F. W. Clarke, “‘A Preliminary Study of Chemical Denudation,” Smithsonian
Mis. Coll., LVI, No: 5; p. 8:

EVOLUTION OF LIMESTONE AND DOLOMITE 337

Experimental evidence on the origin of dolomite by secondary
replacement of calcium chloride——A summary of the principal
experimental methods by which the dolomitization of calcium
carbonate by replacement has been effected follows:

I. REPLACEMENT AT HIGH TEMPERATURE

By heating calcium carbonate and a solution of magnesium
sulphate in a closed tube at 200° C. (Morlot, Jahresb. Chemie
[1847-48], 1290).

' By heating carbonate of lime to over 100° C. with a solution of
magnesium bicarbonate (F. Hoppe-Seyler, Zeztsch. Deutsch. Geol.
Gesell., XXVII [1875], 5009). |

By the action of a solution of magnesium chloride on calcium
carbonate at high temperature (Marignac and Faber, Compt.
Rend., XXVIII [1849], 364).

By saturating chalk with a solution of magnesium chloride and
heating the mass on a sand bath (Saint-Claire Deville, Compt.
Rend., XLVII [1858], 91).

By heating fragments of porous limestone with dry magnesium
chloride in a gun barrel (J. Durocher, Compt. Rend., XXXIII
[7851], 64).

It is probable that the preceding Be ee ae on the replacement
of calcium carbonate have very little significance in relation to
the development of dolomite in the sea, since the continuity of
the life record back as far as the pre-Cambrian, at least, precludes
the possibility of a universally hot ocean. Very locally, as in the
case of the eruption of Krakatao, the required temperatures may
have been duplicated in the ocean. ‘They are more likely to have
been paralleled in some cases of contact, metamorphism of lime-
stones generally following their emergence from the sea.

2. REPLACEMENT ABOVE 60° C.

By action of magnesium sulphate on aragonite in a concentrated
solution of common salt at a temperature above 60° C. (Klement,
Min. Pet. Mitth., XIV [1894], 526).

The same objection holds against the application of this experi-

338 EDWARD STEIDTMANN

ment of the development of dolomite in the sea as was urged
against the preceding group of experiments. The highest tem-
peratures of the sea, resulting from solar heating, on record are
those of the Red Seat (31° C.), and the Lagoons of the Celebes

(2G):

3. FORMATION OF DOLOMITE AT ORDINARY TEMPERATURE AND PRESSURE

By action of magnesium chloride and magnesium sulphate in
water on anhydrite in the presence of common salt and carbonic
aca: (Piatt ir) e700d..05 57)

By action of hydrogen sulphide in water on magnesium and
calcium carbonates, followed by the introduction of carbonic acid
(Piatt ir. ord.) 550).

4. FORMATION OF DOLOMITE AT ORDINARY TEMPERATURE AND HIGH PRESSURE

By the action of sodium carbonate on anhydrite in the presence
of common salt in a concentrated solution of magnesium sulphate
or chloride (Pfaff, zbzd., 562). ;

By the action of magnesium chloride or sulphate in a solution
of common salt on calcium carbonate. The speed of the reaction
is proportional to the degree of concentration of the solution
(Pfaff, ibid., 565).

Pfaff’s experiments are highly creditable in that the replacement
of calcium carbonate by a magnesium salt so as to yield a product
approaching the dolomite ratio was effected without resort to high
temperatures. Doubtless other methods will yet be worked out
whereby this result can be obtained under conditions similar to
those prevailing in the sea. The last experiment by Pfaff is highly
suggestive when compared with the increase in the magnesium
content of marine oozes with depth; that is with pressure (see this
paper, p. 335). However, it does not seem safe to argue that
this has been a very important factor of control, since many
dolomites have very obvious earmarks of shallow-water deposition,
such as ripple marks, cross-bedding, and interstratification with
coarse sands.

* Quoted by F. W. Pfaff, Newes Jahrb. Min. Beilage, XXIII (1907), 573-

EVOLUTION OF LIMESTONE AND DOLOMITE 330

B. THE EVIDENCES FOR THE ORIGIN OF DOLOMITE BY THE META-
MORPHISM OF LIMESTONES AFTER THEIR EMERGENCE
FROM THE SEA .

Direct chemical precipitation of dolomite——The occurrence of
dolomite in veins and vugs of limestone and dolomite is well known.
So far as the recorded facts seem to indicate, direct chemical
precipitation of dolomite in fissures and openings of carbonate
formations, after emergence from the sea, seems to be much more
important than the chemical precipitation of dolomite in the sea
at the present time. However, dolomite as a cement and vein
filler is quantitatively of far less consequence than calcite. Fur-
thermore, it is not certain to what extent dolomite in veins merely
_means the transfer of previous existing dolomite originally developed
in the sea. Direct chemical precipitation of dolomite in formations
after their emergence from the sea, while probably more important
than the chemical precipitation of dolomite in the sea at the present
time, is nevertheless a very subordinate process and cannot be
regarded as an important source of dolomite formations.

Origin of dolomite by leaching limestones after their emergence
from the sea.—The dolomitization of limestones after their emer-
gence through leaching is a very important process wherever both
the calcium carbonate and dolomite are originally present, because
of the differential solubility of the two carbonates. Unquestion-
ably a unit volume of water as it enters the soil, but charged with
atmospheric gases, is a much more efficacious solvent than an
equal volume of sea water, but the total volume of sea water which
is effective in leaching carbonates in the sea is vastly greater than
the volume of water in the lithosphere. Leaching of limestones
by underground waters probably changes the ratio of calcium to
magnesium but little excepting near the surface, because the
porosity, slumping, and faulting which would need to follow from
converting a magnesian limestone containing even 13 per cent
of magnesium carbonate into a dolomite through leaching is
not at all evident in dolomite formations. Evidence is cited
showing that weathering does increase the percentage of
- magnesia in limestones. Since effective leaching of limestones
by ground water is related to weathering, it is improbable that

340 EDWARD STEIDTMANN

this process accounts for the stratigraphic separation of limestones,
magnesian limestones, and dolomites, or for any large proportion
of the dolomite in nature.

Origin of dolomite by secondary replacement of limestone.—
Secondary dolomitization along fissures had been described by
Prestwich, Geikie,? Bain,’ Pfaff,4 Spurr,5 and others. The altera-
tion of limestones by hot, magnesian spring waters at Aspen,
Colorado, described by Spurr is significant, but obviously, second-
ary replacement by underground water seems to be only local.
A brief consideration of the chemistry of ground water and of the
ocean is suggestive in showing the probabilities for the relative
replacing power of sea water and underground water. Sea water‘
contains calcium and magnesium in the ratio of 1 to 3.11. The
salinity is 3.301 to 3.737, of which 1.197 per cent is calcium and
3.725 per cent magnesium. The constitution of underground
water is variable and depends upon the local composition of the
rocks from which it is taken. Underground water of terrestrial
origin is nearly free from mineral matter at the start but contains
solvent gases from the atmosphere. Obviously, if a unit volume
of unmineralized underground water comes into contact with a
unit weight of carbonate rock, solution follows until equilibrium
is attained between the solid and liquid phases which are in contact.
If the temperature, pressure, and the volume of water remain
unchanged nothing further results. It is this history of the source
of the salts in terrestrial underground waters which is unfavorable
to replacement.

In humid regions, underground waters are essentially carbonate
waters in which the principal positive ion is calcium. ‘The follow-
ing analysis may be taken as illustrative:

t Prestwich, Geology—Chemical, Physical and Stratigraphical (Oxford, 1886),
I, 133-44.

2 Geikie, Textbook of Geology (3d ed.; MacMillan, London, 1893), 321.

3 Bain, ‘‘ Preliminary Report on the Lead and Zinc Deposits of the Ozark Regions,”
Twenty-second Ann. Rept. U.S. Geol. Survey, Part II (1901), 208-10.

4 Pfaff, op. cit., XXIII (1907), 529-80.

5 Spurr, ‘“‘Geology of the Aspen Mining Dist., Colorado,’’ Mon. U.S. Geol. Sur-
vey, XXXI (1898), 210-91.

5 Mean of 77 analyses of ocean water from many localities collected by the Chal-
lenger expedition. Quoted from Bull. 330, U.S. Geol. Survey, 94.

EVOLUTION OF LIMESTONE AND DOLOMITE 341

COMPOSITION OF EXCELSIOR SPRINGS, MISSOURI:

SALINITY 489 PARTS PER MILLION OF WATER, OR ABOUT 0.4 PER CENT

Ca 29.28
Mg Bes
Co; 55.92

Ratio of Ca to Mg 9.3:1

The calcium carbonate of the ocean bottom is in contact with
a solution high in magnesium and low in calcium, largely derived
from the lands and not from the ocean bottom. The calcium
carbonate of the land areas is on the average, so far as humid
climates are concerned, in contact with carbonated waters high
in calcium and low in magnesium whose salts are derived from
the decomposition of the rocks through which they circulate. In
the light of experimental evidence, on the replacement of calcium
carbonate by magnesium carbonate, where are the conditions
more favorable for dolomitization by replacement, in the ocean or
in the sea of underground water? Of course there are analyses
of underground waters which show a high content of magnesium,
which could possibly cause dolomitization, but these seem to be
either exceptional or local.

C. EVOLUTION VERSUS THE METAMORPHISM OF LIMESTONES AFTER
THEIR EMERGENCE FROM THE SEA AS EXPLANATION FOR THE
INCREASE IN THE RATIO OF CALCIUM TO MAGNESIUM OF LIME-
STONES AND DOLOMITES WITH GEOLOGIC TIME
Evidence has been presented for both the development of dolo-

mite in the sea and its origin by the metamorphism of limestones

after their emergence from the sea. Magnesian limestones can
develop in the sea from a combination of organic and inorganic
processes. The known inorganic processes are direct chemical
precipitation, leaching, and secondary replacement. These may
also be effected through the agency of underground water. Evi-
dence has been presented to show that these processes are operative
in the sea on a much larger and more uniform scale because of the
chemical properties of the sea as compared with those of under-
ground water. Underground waters derive their dissolved mate-
rials from the rocks through which they circulate, and generally

™ From Bull. 330, U.S. Geol. Survey, 150.

342 EDWARD STEIDTMANN

are high in calcium and low in magnesium, whereas the sea derives
its materials largely from the lands and not from the ocean bottom.
Sea water is low in calcium and high in magnesium, and is therefore
a more favorable as well as a more universal medium for effecting
the dolomitization of the ocean bottom than is underground
water for the dolomitization of the rocks through which it circu-
lates. The direct evidence for the dolomitization of limestones
by underground waters which has been presented shows only
local dolomitization along fissures and other openings, principally
in the belt of weathering or in localities permeated by waters of
unique chemical compositions, such as hot magnesian springs.
The occurrence of dolomites of vast thickness and extent and the
interstratification of limestones and dolomites cannot therefore
find a ready explanation in the mutative agency of underground
waters. Excepting for certain local occurrences, dolomite forma-
tions seem to have developed in the sea, rather than by the meta-
morphism of limestones after their emergence from the sea. The
evolution of dolomite and limestones through a decline in the
deposition of dolomite with time, therefore, seems to have a high
degree of probability. Consequently, the gradual alternation from
the predominance of dolomite in the ancient sediments to the
dominance of limestones of a high ratio of calcium to magnesium
in more recent times has probably been due to gradual changes
in the condition of deposition in the sea.

WHAT FACTORS CONTROLLING THE DEPOSITION OF CAL-
CAREOUS MARINE DEPOSITS HAVE UNDERGONE A
GRADUAL EVOLUTION RESULTING IN THE EVOLU-
TION OF THE LIMESTONES AND DOLOMITES?

Four factors directly control the composition of the materials
precipitated on the ocean floor: namely, pressure, temperature,
life processes, and the chemical composition of the sea. Which of
these factors has undergone a progressive change, reflected in the
evolution of limestone and dolomites? It is almost needless to
consider whether the pressures on the ocean floor have undergone
a progressive evolutionary change within geologic time. All the
water-deposited sediments found on the continents appear to have

EVOLUTION OF LIMESTONE AND DOLOMITE 343

the character of deposits now forming in shallow or moderate
depths. None are like the abysmal deposits of the present ocean,
a forceful argument for the permanence of the continents and the
oceans. Nor is there any probability that the temperature of the
ocean has undergone a progressive change which would account
for the evolution of limestones and dolomites. The continuity of
the. life record down to the base of the Cambrian precludes the
possibility of any marked change in the temperature of the ocean
throughout Zoic times. But even beyond the Cambrian this
relative uniformity of temperature may have persisted for a period
of time, as long or even longer than from the Cambrian to the
present, for paleontologists believe that approximately nine-tenths
of the evolution of life into main stocks was completed at the begin-
ning of the Cambrian. All the phyla are represented in the Cam-
brian excepting the vertebrates, and the fact that no vertebrate
fossils have been found in the Cambrian cannot be regarded as
positive proof that even they did not exist at this remote period
of earth history. On the other hand, more and more evidence
is accumulating in favor of Chamberlin’s philosophic conception
that the temperature of the ocean and the climatic conditions of
the continents have undergone oscillations in consequence of
periodic, areal changes of the lands with respect to the sea; that
periods of land expansion are characterized by zonal, diversified
climates, tending toward world-wide aridity and refrigeration,
while periods of maximum oceanic expansion are associated with
climatic uniformity, moderation, and humidity. There is then no
probability that the temperatures of the ocean have undergone an
evolution consonant with the evolution of dolomite and limestone.

Could the evolution of living organisms have been the control-
ling factor in the evolution of limestones and dolomites ?

It would be difficult to disprove that organic control was a
factor in the problem. Organisms play a gigantic réle in the dis-
tribution of lime at the present time, and have for ages past.
Biologists, however, lend considerable support to the hypothesis
that organic activities are adaptations to physical and chemical
environment, rather than creators of environment. In the long
run, they may cause profound changes in environment, but the

344 EDWARD STEIDTMANN

keynote of their activity is adaptation rather than control. The
selection of potassa rather than soda by the land plants and the
selection of soda in preference to potassa by marine plants has been
cited as evidence for the adaptation of life processes to chemical
environment. The preference of lime-secreting organisms for
calcium rather than for magnesium may be a similar adaptation.
It is suggestive that calcium carbonate is the principal salt contrib-
uted to the sea, and that in localities most favorable to life, lime
carbonate is the most insoluble of the important salts of the sea.
Recent biological studies have also shown that magnesium salts
are to a certain extent deleterious to life processes. While the
relation of life processes to environment is problematical, the
evidence favors the physical control of life processes, rather than
the control of environment by life processes.

Even if the immediate control of the evolution of carbonate
rocks was largely by organic agencies, the causation of the control
may logically be looked for in the environment. The change in
the calcium magnesium ratio, which characterizes the evolution
of the carbonate rocks, suggests under this hypothesis that it is
related to a similar change in the calcium magnesium ratio of the
materials contributed to the sea. It has been indicated already
that waters containing.a high proportion of magnesium to calcium
are more efficient in causing the development of dolomite than
those which do not. The salts of the sea are inherited from the
metamorphic processes which have worked the earth over and over
again. The circulation of the rock materials from one environment
to another involves adaptations. The materials adapted to the
new conditions tend to be stable. Others undergo conversion to
new mineralforms. Some, finding no place in the new environment,
are expelled and may finally reach the sea, where they again under-
go environmental adaptations. Could it be possible that the ratio
of river-borne calcium to magnesium, which is now approximately
6 to 1, has undergone an evolution throughout geologic times
marked by a gradual increase in calcium and decrease in magne-
sium? <A progressive change in the proportions of calcium and
magnesium contributed to the sea might have been consummated
either by a progressive change in the agents and processes of

EVOLUTION OF -LIMESTONE AND DOLOMITE 345

metamorphism and sedimentation or by a progressive change
in the calcium and magnesium content of the lands. It cannot
very well be assumed that the nature of the agents and processes
which contribute calctum and magnesium to the sea has undergone
any marked change during geologic time. The continuity of the
life record, the uniformity of sedimentation, and the duplication
of climatic conditions down to the remote past speak against it.
How then could the constitution of the lands, apparently the only
remaining alternative, undergo a progressive change which in
turn caused a progressive Increase in the ratio of calcium and
magnesium contributed to the sea, under uniformitarian processes ?
The answer to this problem is sought in the nature of the redis-
tribution of calcium and magnesium in consequence of meta-
morphic and depositional processes.

[To be continued|

THE RECURRENCE OF TROPIDOLEPTUS CARINATUS
IN THE CHEMUNG FAUNA OF VIRGINIA?

E. M. KINDLE
U.S. Geological Survey

For many years after the standard sections of the New York
Devonian formations and their faunas had become well known,
the brachiopod Tropidoleptus carinatus was supposed to be con-
fined in its geologic range to the 1,100 or 1,200 feet of shale com-
prising the Hamilton formation in central New York. No trace
of this fossil has ever been found in the typical Genesee and Portage
faunas which follow the Hamilton fauna in west central New
York. The entire absence of the species from the Genesee and
western Portage faunas of New York seemed to indicate that the
life of the species came to an end with the close of Hamilton sedi-
mentation in central New York. But the discovery of T. carina-
tus in the Chemung of southern New York 2,000 feet above the
top of the Hamilton by Professor H. S. Williams? several years ago
proved that this species instead of becoming extinct at the close
of the Hamilton had only changed its habitat. More recently
Williams and Kindle? have found that Tvopidolepitus carinatus
and other well-known Hamilton species comprise the major part
of the fauna at certain Chemung horizons in southern New York
2,000 feet or more above the top of the Hamilton formation. In
this paper it. will be shown that this and other Hamilton species
reappear in the Chemung fauna of Virginia as they do in New
York. The appearance of T. carinatus in the Chemung fauna of
Virginia in abundance is especially notable because it is seldom
found at the horizon of the Hamilton fauna so far to the southwest
in this part of the Allegheny region as the occurrence in the rocks
of Chemung time which will be described.

* Published by permission of the Director of the U.S. Geological Survey.

2 Bull. U.S. Geol. Survey No. 3 (1884), 24.

3 Amer. Jour. Science, XIII (1902), 427-30; Bull. U.S. Geol. Survey No. 210

(1903), 90-91.
346

TROPIDOLEPTUS CARINATUS IN CHEMUNG FAUNA 347

This recurrent Hamilton fauna was collected in Bath County,
Virginia, near Mountain Grove post-office. The relationship
which it bears to the other faunas which are known in the section
from which it comes will be indicated by the following section of
the rocks exposed along Little Créek at Mountain Grove post-
office.

SECTION AT MOUNTAIN GROVE, VA.

Feet
h. Thin-bedded, hard, gray sandstone and interbedded shale 700

g. Thin-bedded, hard, gray sandstone and interbedded shale 100
jf. Rather hard, sandy, dark-blue shale and some thin bands
ofsandstone with Portage tauna:.... 3... 0.55... bsl6.-.... 600 =
cmeblackshardetissilessmalesi is. means. oceania klek es dass TOO
Crm COVCrCCR rin ree ree rhea Sheltie La Nua uid wt 70
c. Hard, black, and dark greenish-gray calcareous shale...... 6
Grblack blocky itoughishalen ey ue sce he sce sie dae Ss we 20
a. Dark, coarse, ferruginous sandstone with frequent concre-
HONS OMpy mites) (OLriskany,iys se. se als sees sb os 20-+

The sandstone at the base of the section holds the usual type of
Oriskany fossils and clearly represents the Oriskany sandstone.
The fauna of the lower 26 feet of calcareous and blocky shale is
rather meager in this section as compared with the rich fauna often
found at this horizon. The species collected from it are the
following:

FAUNULE c, MOUNTAIN GROVE, VA.

Orbiculoideatodiensissmediat ie.) se) sees ss ie sn ss a
Anoplothecaacutiplicatannen sce ccs enero scl. once luke wee oat C
Comullariag Si ieee Mary sxn eee eam ete tee on teen el WS ee r

This faunule taken alone, of course, could hardly be cited as sat-
isfactory evidence of a definite horizon. An extended study of
the fauna found at this horizon by the writer throughout an exten-
sive region in the Allegheny Mountains has shown, however,
that the horizon is that of the Onondaga limestone. The greater
part of the Hamilton horizon is covered in the section.

The next higher fauna which was collected from this section is
shown in the following list of species from the lowest beds in the
sandy shales marked f in the section outcropping at Cash’s store.

t The Onondaga Fauna of the Allegheny Region, Bull. U.S. Geol. Survey (in press).

348 E. M. KINDLE

FAUNULE f, MOUNTAIN GROVE, VA.

Ontaria suborbicularis

Paracardium doris

Styliolina fissurella

Bactrites aciculum

Orthoceras sp.

Probloceras cf. lutheri

Tornoceras uniangulare

The student familiar with the western Portage or Buchiola
retrostriata’ fauna will at once recognize in this faunule a repre-
sentative of that fauna. Its occurrence at a definite horizon in
Virginia and Pennsylvania has been previously noted by the
author.? Clarke? and Swartz* have recognized the same fauna
in western Maryland. It should be noted here that the Buchiola
retrostriata (G. speciosa) fauna listed by the author from the
White Sulphur Springs, Virginia,$ section is not the faunal equiva-
lent of the B. retrostriata (G. speciosa) fauna of Williams,° but
comprises only the upper portion of Williams’ fauna. As the
term is used by Professor Williams in Bulletin 244 it includes at
least three distinct faunas, each of which has a fairly definite posi-
tion in the sections. The writer’s past and present usage makes it
include only the latest of these three—the Portage—thus making
it synonymous with the western Portage or Naples fauna of New
York. The recorded range of this species makes it permissible
to use the name in Professor Williams’ comprehensive manner if
it is desirable to consider these several faunas collectively. But
the writer prefers the more restricted usage adopted by Professor
Williams in an earlier paper,’ according to which it includes only
the western phase of the Portage fauna. The Portage fauna
appears to characterize about 600 feet of the Mountain Grove
section. Although the section is mostly exposed and the order
of succession of the different parts is clear, the local buckling of

t This fauna has also been called the Manticoceras intumescence fauna and Naples
fauna in New York.

2 Bull. U.S. Geol. Survey No. 244 (1905), 35, 40-41; Jour. Geology, XIV (1906),

633.
3.N.Y. State Mus. Mem. 6 (1904), 212. 4 Jour. Geology, XVI (1908), 340.

5 Bull. U.S. Geol. Survey No. 244 (1905), 35. °Lbid., 51.
7 Bull. U.S. Geol. Survey No. 210 (1903), 115.

TROPIDOLEPTUS CARINATUS IN CHEMUNG FAUNA 349

some of the softer beds leaves some uncertainty regarding the
exact thickness of the section.

It is with the next fauna in the section that this paper is chiefly
concerned. This fauna appears after the bluish-gray sandy shales
and very thin sandstones have given place to very hard thin-bedded
sandstones as the dominant lithologic characteristic of the section.
In beds of this kind in division g of the section occurs the first
appearance of the Chemung fauna. The following is a list of the
species collected from this horizon:

FAUNULE g, MOUNTAIN GROVE, VA.

ETOGduUCtellarswrrpesemes ene tuns chim cormoaes i Bil Or ae ito Ue G
@amarotoechiasch.congregata.a. 2: -e..ccc0.-. oes sane: C
TE CIOV ANGUS ESP rere ee rte cI a cial ce clea aha gine kadal oer C
PANETa PESO O Sate emer eee ere OS Shirdi Seg a5 essen ye atape wis eaeie oem C
Rihipidomellatimpressavas 10 oye 5) eke s ia sstes cee oe ei coe os r
Rhipidomella cf. penelope...... SE ae he era Pa age aa r
SEMIZOPNOTAMEIOL Arye ne uate cin eee vise cd CURE! caoete oe es G
ATMO COG MAR ITM OMe tata rere veces cos Sookens woes Gade abe, onc le G
SchuchertellagchenmumGensiswes seers ee sie eee oe r
Welithyrissmmesacostalisnmac ts ask ice soe cuales Rint ecw tek C
Spite rate Calls eee el eae -w. Vasc Soaps Sashes eee aes ended eos eee oe C
Reticulariachinloriatanies sca. a6 tess. ye nae coon aeeceiiel ae r
sbropidoleptusecarimatusyu.. ser. 40 Maen s Seine ete ns Seco): a
iy talancachemumn gensiss ecm ai. co cis gehen ale cede euslaieeeee che r
Miodiomonp lars prmacneinit ie ae a ata te ete aiots. oo ecm itgee aie atte r
INuculutestchroblongatuses.. 2a \cfen esas a escic fais see ee r

Cyclonema sp.

The stratigraphic position of this fauna several hundred feet
above a typical Portage fauna shows plainly that it lies far above
the Hamilton horizon. Its association with Schizophoria tioga
and Mytilarca chemungensis indicates that it is here associated with
a Chemung fauna. In the next division of the section above this
we find Spirifer disjunctus and other well-known Chemung fossils
as shown in the following list from division / of the section:

FAUNULE s, MOUNTAIN GROVE, VA.

PN @ Gates aren ys tee ce revees ae RIA eae atu angie een poate dyin r
GONE TESESCIt UAE ean ete s et fren gets yeah ee ps I earn C

350 E. M. KINDLE

Atry pa Spinosay a iiiiys ca iee a ieee cakes Oe i pee een eee G
Stropheodonta (Douvillana) mucronatus................... a
Stropheodonta perplama var. mervoSae syste alr ole eerie r
Schizophoria toga cas occ oy eenah persia sie (men atattig te cg wrote G
Rhipidomella/spi2y 2 atin. eas tert eae ence aes ae Uh
Camarotoechiasspas rin. dcr seen der ys cuca ease te eerie ai ene r
Spiriter:disjume bus ese (ch rere: wees se eae elias) amereesonae eeceeneenee C
Bdmondia spe aiee. ois os ee Pn MAME ts pees Pen r
Schizodus/rhombeusSijcc30 0 cam ee eee eee eg rae r
Sphenotus .contractus...c2 55 oe. os eat eet trae eect eee C
1 Ba. <oyaYsa toss) oe mIRC Pe nts een OGD Hi Miabls WPaaUG a'o 6 r

The case of recurrence which has been cited involves a somewhat
different phase of the phenomenon from that represented in the
New York occurrences of T. carinatus in the Chemung.

The presence of a recurrent Hamilton species like Tropidolep-
tus carinatus in the Chemung fauna of southern New York involves
its withdrawal from at least the major part of the New York area
at the end of Hamilton sedimentation to some part of the sea
furnishing a more congenial environment than that which accom-
panied Genesee and Portage sedimentation. In the newly
adopted habitat or in a small portion of the old one it found a
haven where those conditions of the Hamilton sea which were
essential to its life were maintained throughout Genesee and
Portage time. With the initiation of Chemung sedimentation
T. carinatus extended its habitat back again over a part of the
area which it had previously occupied.

The case of recurrence which I have given in Virginia does not
involve, as in New York, a retreat of the species before unfavorable
conditions at the close of the Hamilton and later recovery of lost
territory, since it apparently never occupied this territory in Ham-
ilton time. It represents instead the acquisition of a new habitat
which had been outside the limits of its geographical range in the
Hamilton sea. The writer’s study of the Devonian faunas in the
Allegheny region indicates that the typical Hamilton fauna with
T. carinatus does not extend as far to the southwest as Mountain
Grove, although the Hamilton sea extended much beyond that
point to the southwest. The occurrence of a Hamilton species
in abundance in the Chemung fauna of this part of Virginia thus

TROPIDOLEPTUS CARINATUS IN CHEMUNG FAUNA 351

seems to indicate that the marine biotic conditions of the New
York Hamilton and the Virginia Chemung seas were more nearly
alike than they were in different parts of the same sea in the two
states during Hamilton sedimentation.

A matter of some interest and importance in connection with
the recurrence of this species and its associates relates to the
location of its Portage habitat, or place of retreat between the
close of Hamilton and the beginning of Chemung sedimentation.
It has been shown by Prosser* and others? that in eastern New
York the Hamilton fauna including Tropidoleptus carinatus con-
tinued in a slightly modified form to live on during Portage time.
In other words, this species and some of its allies at the close of
Hamilton time became extinct in central and western New York
but survived in a narrow belt along the eastern margin of their
old habitat and continued to live near the eastern shore of the
Appalachian Gulf throughout Genesee and Portage time. (See
Eies +h)

In Pennsylvania the writer’s work has shown that the Ithaca
and Portage faunas bear the same geographic and stratigraphic
relations to each other that they do in New York. In western
Pennsylvania the Portage formation is characterized by a typical
western Portage or Naples fauna. On the Susquehanna River
an Ithaca fauna occupies the same horizon which is held by the
Portage fauna in the Altoona section. East of the Susquehanna
River 35 miles, at Pine Grove, the writer has recently collected a
faunule of the Ithaca fauna which shows a more prominent Ham-
ilton element than the fauna exhibits at the Susquehanna River.
It includes Tropidoleptus carinatus, as will be seen from the follow-
ing list of its species:

t“The Classification and Distribution of the Hamilton and Chemung Series of
Central and Eastern New York,” Fifteenth Ann. Rep. State Geol. New York (1897),
208-14.

2H. S. Williams, ‘‘The Correlation of Geological Faunas,”’ Bull. U.S. Geol.
Survey No. 210 (1903), 71-72; John M. Clarke, “‘The Ithaca Fauna of Central New
York,” Bull. N.Y. State Mus. No. 82 (1905), 53-65.

3 E. M. Kindle, ‘“‘Faunas of the Devonian Section near Altoona, Pennsylvania,”
Jour. Geology, XIV (1906), 633.

4H. 5S. Williams and E. M. Kindle, ‘‘Contributions to Devonian Paleontology,
1903,” Bull. U.S. Geol. Survey No. 244 (1905), 69-92.

352 E. M. KINDLE

ITHACA FAUNA AT PINE GROVE, PENNSYLVANIA

AsulopOrar’spsn ec ieee see tne cts Sagem ch eau eine ore iP
Cystodictya» meek i552. Mane sso cuaeatey eck tet naa ean C
Chonetesiscitulai oe nario e coeh genres pet eam eae ae a
Spitiier pennatusnvar DOSteTUSm a eens re ere: 2 @
Tropidoleptusicarima tus 7. eee tate aera ies acon ene C
Palaeoneidlo plana 24. nace See te sce eats chee ee C
Modiomorpha,ciasubalatay 3-year eee i
Goniophoradminor 2554 oh re cen 8 creer ches eee eat oe aoa r
Paracy clas liratus,... ices 2 rahe oe as cues 4 pete ae a On eee eninge r
Actinopteria-MeriStraliSi« eels Ge cree ee earner aan C
Coleolustaciculumir cs. Sei oe ee nets Mec oe r
Rleurotomarniarcapillariasios 5.0 he eee reo aa nae r
Bleurotomania sulcomargina tay. s-1n ees aero ee eee 6
Murchisonrascivledag6 3 icc ae aii ate aeons Wann aap ae eae r

From central and eastern Pennsylvania the Ithaca fauna extends
southward across Maryland far into Virginia. The Portage and
Ithaca faunas occupy the same relative stratigraphic and geo-
graphic positions in this southerly area’ as in New York state,
the former having its maximum development to the westward of
and parallel with the Ithaca fauna. Evidence that Tropidoleptus
carinatus lived during Portage time near the eastern margin of the
Appalachian Sea in Virginia as well as in Pennsylvania and New
York is furnished by a collection representing the Ithaca fauna
which the writer made at Bells Valley, Virginia. In this collec-
tion T. carinatus is a very abundant species, while another pre-
Portage species, Rhipidomella vanuxemi, occurs sparingly with it.

The relation which Tropidoleptus carinatus bears to Hamilton,
Portage, and Chemung sediments may be illustrated by the
accompanying diagram which shows the easterly restriction of the
species in New York during Portage time and the westerly exten-
sion of its habitat during Chemung time. The easterly or coast-
wise restriction of the species at the close of the Hamilton could
be graphically shown for Pennsylvania and Maryland by diagrams
of similar character, except that the Tully limestone would be
omitted.

E. M. Kindle, Bull. U.S. Geol. Survey No. 244 (1905), 35, 41, faunules 1380B
and 1382D; Charles K. Swartz, Jour. Geology, XVI (1908), 328-46.

TROPIDOLEPTUS CARINATUS IN CHEMUNG FAUNA 353

When it is recalled that the geographic range of this species
in the eastern United States during the Hamilton extended from
the Hudson River and the eastern part of the Allegheny Mountains
to Michigan, Indiana, and southwestern Illinois, it will be seen
that its east-west distribution was reduced during Portage time
to a very small fraction of that which it enjoyed during Hamilton
time. Our present knowledge of its occurrence in the Chemung
indicates that only a very small part of its east-west Hamilton
range was regained during the Chemung. The north-south
distribution of the species in the Allegheny region did not, however,

Eastern New York

Central New York (Chenango Valley)

Chemung
formation

{ Spirifer disjunctus fauna

— ————— mate Se Tropidoleptus
mae carinatus |

Portage : SSS
ee ) Buchiola retrostriata fauna 2

Genesee shale { ee aaa
Tully limestone = : a cf

: Tropidoleptus carinatus fauna
Hamilton

formation |

0 10 20 30 40 50 Miles

eee el

Fic. 1.—A diagrammatic east-west cross-section of the Middle and Upper Devo-
nian of southern New York showing the relations of Tropidoleptus carinatus to the
western faunas during Portage and Chemung time. Total thickness of the section is
about 2,700 feet.

differ greatly during the Portage and Chemung epochs from what
it had been during the Hamilton. In this direction it appears
to have extended its range slightly in Chemung time beyond what
it had been during Hamilton time. During Portage time the
species was confined to a sublittoral belt, narrow but long, which
reached south into Virginia along the eastern shore of the Appa-
lachian sea. From the limits of this coastwise belt of the sea the
more favorable conditions of environment which accompanied
the initiation of Chemung sedimentation encouraged the migration
of its colonies westward into the areas where we now find them
in the Chemung of New York and Virginia. These colonies

354 E. M. KINDLE

appear to have experienced a succession of alternate extensions
and withdrawals in the New York Chemung.

It is essential to a clear understanding of the interrelationship
of these distinct but contemporaneous faunas to recognize the
fact that zodlogical provinces were often as distinct in the Paleozoic
seas as in those of the present. In the Devonian we know that
there were such provinces, but as yet we know but little of their
limits in any given epoch. We also know comparatively little
about the factors which set the limits to faunal provinces. It is
safe to conclude, however, that the recurrence of a fauna has
been due to the oscillation or migration of the factors which
conditioned its geographical distribution. Attention has been
called to one of these factors by Ulrich* in discussing the
recurrence of a Spergen fauna in the Ste. Genevieve limestone.
He conceives one of the conditions inducing the recurrence
of this fauna to have been ‘‘the subsidence or modification
of barriers allowing communication with seas more perma-
nently inhabitated by the invading fauna.’ The probable
combination of two factors which are no doubt often effective in
controlling recurrence is cited by Bagg in discussing the recurrence
of a Cretaceous brachiopod in the Eocene of Maryland. Bagg?
believes this case of recurrence to have been due to a deepening
of the sea south of New Jersey, assisted perhaps by cold currents
from the north which killed off the other Cretaceous species and
encouraged the southward migration of a shell which previously
had lived in the New Jersey region.

While the development or removal of land barriers and changes
in the character of sediment have doubtless been at times influen-
tial in causing the recurrence of faunas, it is probable that changes
in the temperature of marine waters have much more frequently
been the direct effective agency in causing recurrence. Among
the agencies controlling faunal distribution it is most probable
that temperature has in the past, as in the present, been a factor
of paramount importance. The recurrence of a species necessarily
represents the recurrence of those factors in its environment which

* Prof. Paper U.S. Geol. Survey No. 36 (1905), 49.

2 Am. Geologist, XXII (1808), 272-373.

TROPIDOLEPTUS CARINATUS IN CHEMUNG FAUNA 355

have throughout its life history controlled its distribution. Recur-
rent faunas, therefore, afford special opportunities to discover the
factor most essential to the life of the fauna in a given case through
elimination of those factors which are common to the sediments
from which it is absent and in which it makes its earlier and later
appearances. With reference to the sediments, the recurrence
of a species after long absence from the section thus affords evi-
dence of similar conditions having been present in widely separated
formations, the importance and significance of which might other-
wise not have been apparent.

In the light of these general considerations we may inquire
into the cause of the eastward retreat of the species which has been
shown to have occurred at the beginning of Genesee sedimentation
and its later westward and southwestward migration. The
evidence of such a movement has been cited on a preceding page.
The close of Hamilton sedimentation is marked in western New
York by a great change in the character of the sediments. The
sandy and often calcareous shales of the Hamilton are succeeded
by the thin band of the Tally limestone and the fissile black
carbonaceous shales of the Genesee in the central and western
parts of the state (see Fig. 1). When these black Genesee
and the succeeding lighter-colored shales of the Portage are
not entirely barren they are occupied by a fauna of ‘evident
deep-water habit having nothing in common with the pre-
ceding Hamilton fauna.’’ These black shale sediments follow-
ing the Hamilton extend southward beyond the Potomac River.
This sharp contrast between the sediments and faunas of the
Hamilton and those of the Genesee shales includes the total dis-
appearance of the large coral fauna of the Hamilton. The annihi-
lation at the close of the Hamilton of all fossils which, like corals,
require shallow waters, and the shifting of those species which
survived to the comparatively shallow coastwise waters points
plainly to the deepening of the sea at the close of Hamilton time.
Much additional evidence for the deep-sea conditions which pre-
vailed during Genesee and Portage time in western New York

t John M. Clarke, ‘“‘The Naples Fauna in Western New York,” N.Y. State Mus.
Mem. No. 6 (1904), 211.

B56 E, M. KINDLE

has been given by Dr. John M. Clarke’ and requires no restatement
here. A lower temperature of the water doubtless accompanied
the deepening of the sea during early Genesee time and was prob-
ably the chief immediate cause of the complete disappearance of
the shallow water fauna of the Hamilton from a large part of the
Devonian sea with the appearance of the pelagic Genesee fauna.
The sea became shallow again during Chemung time. This is shown
by the ripple-marked sandstones which may be seen in Chemung
sediments from New York to southern Virginia. That the rem-
nant of the Hamilton fauna which had survived till Chemung
time in the shallow coastwise waters in the eastern margin of the
Devonian sea found in the Chemung sea a temperature similar
to that of the old Hamilton sea is attested by such colonies as the
one which has been described from Virginia. “

The distribution of Tropidoleptus carinatus in the Chemung
sediments as detached, often widely separated, colonies is in some
degree comparable with that of Ostrea virginica along the present
Atlantic coast. This warm-water species is unknown along wide
stretches of the northern New England coast but in the Gulf of
St. Lawrence flourishes in waters, which in their deeper parts
afford a habitat for such Arctic forms as Mya truncata. That a
low temperature is as essential to the life of the latter as is a high
temperature to the former is illustrated by the fact that while
in the Gulf of St. Lawrence M. truncata is found in the deeper waters
only, in Greenland waters it is said to be sufficiently common at
low water to furnish food for the Arctic fox and other land animals.’
The character of the geographical conditions which permit repre-
sentatives of the south Atlantic and north Atlantic coast faunas
to live on adjacent parts of the sea bottom is indicated in the
following quotation from Doctor MacBride.

The whole north coast of Prince Edward Island is fringed by a series of
parallel sand-bars, and it is owing to this circumstance that the oyster is able
to flourish there. All who know the coast of the Gulf of St. Lawrence are
aware that the water even in summer is very cold; so cold indeed that though

UO pucit.

2J. F. Whiteaves, Catalogue of the Marine Invertebra of Eastern Canada (Geol.
Surv. of Canada, toot), 148.

TROPIDOLEPTUS CARINATUS IN CHEMUNG FAUNA 357

the adult oyster could live in it, it could not reproduce itself, for the larvae
would perish. But as the Gulf water flows over the sand-bars and shoals
alluded to, it becomes heated up by the summer sun, and reaches a tempera-
ture which permits, in favorable years at least, of successful spawning. Oysters
are accordingly confined to such places on the coast of Canada as present
conditions similar to those mentioned above. They exist in the Baie de
Chaleur, in some of the shallower inlets on the New Brunswick coast, at a few
points on both shores of Prince Edward Island, and on the Northern Coast
of Nova Scotia. In every case, however, we have to do with isolated colonies
inhabiting warm spots surrounded by a great belt of cold water, so that al-
though the larvae could be carried to great distances in the fortnight of their
free-swimming life, they are all killed off by the cold.

Protecting bars may at times have been a factor in modifying
the temperature of the Devonian sea where Portage and Chemung
colonies of T. carinatus gained a foothold, as they are now in shelter-
ing the oyster at Prince Edward Island. But there can be no doubt
that all times during the upper Devonian the eastern or coastwise
belt of the Appalachian gulf was shallower than its more pelagic
portion. Its waters must also have been comparatively warm,
at least during the’ spawning season of its molluscan fauna. Since
Tropidoleptus carinatus is confined in the late Devonian to the
sediments of this belt of comparatively shallow sea, and conse-
quently warmer water, we must conclude that its restriction
and late survival here was due primarily to the higher average
temperature of this part of the Devonian sea.

tE. W. MacBride, ‘“The Canadian Oyster,” Canadian Rec. of Sci., IX (1905),
154-55.

FURTHER DATA ON THE STRATIGRAPHIC POSITION
OF THE LANCE FORMATION (“CERATOPS BEDS”):

F. H. KNOWLTON

In June, 1909, I published a paper entitled: ‘The Stratigraphic
Relations and Paleontology of the ‘Hell Creek Beds,’ *‘Ceratops
Beds,’ and Equivalents, and Their Reference to the Fort Union
Formation.’”? In that paper, as suggested by the title, the con-
clusion was reached that the beds considered—namely, the “ Hell
Creek beds,” ‘‘Ceratops beds,” ‘‘somber beds,” and “Laramie”’
of many writers—are “‘stratigraphically, structurally, and paleon-
tologically inseparable from the Fort Union, and are Eocene in
age.

It was expected that this somewhat radical innovation would
be received with a storm of protest, especially by the vertebrate
paleontologists, but so far as known to the author only three
papers have since appeared which deal specifically with the posi-
tion of the ‘‘Ceratops beds.” These comprise two papers by
Dr. T. W. Stanton and one by Dr. O. P. Hay.

As two field seasons have intervened since the publication of
my paper, during which important data were secured confirming
the position there assigned the Lance formation,’ it seems oppor-
tune to present the case as it now stands. The areas in which
these observations were made are in the main in Eastern Wyoming
and Eastern Montana and adjacent portions of North and South
Dakota.

« Published with the permission of the Director of the U.S. Geological Survey.

2 Proc. Wash. Acad. Sci., XI (1909), 179-238.

3 The name Lance formation has been formally adopted by the U.S. Geological
Survey in place of the term ‘‘Lance Creek beds” or ‘‘Ceratops beds.”” Wherever
Lance formation is employed in the following paper it is to be understood as including

“ance Creek beds,” ‘“‘Ceratops beds,’ ‘Hell Creek beds,”’ “somber beds,” ‘Lower
Fort Union,”’ and beds identified as “‘ Laramie” by many writers.

358

STRATIGRAPHIC POSITION OF LANCE FORMATION 359

NEAR THE MOUTH OF THE MEDICINE BOW RIVER, CARBON COUNTY,
WYOMING

In the early nineties, when the late J. B. Hatcher was searching
for new fields that might possibly supply additional material
belonging to the then recently discovered group of horned dino-
saurs (Ceratopsidae), he made an examination of the country lying
along the North Platte River some twenty-five or thirty miles
north of old Fort Fred Steele, in Carbon County, Wyoming.
Hatcher observed fragmentary remains of dinosaurs at a point
which he indicated’ as ‘“‘on the North Platte River opposite the
mouth of the Medicine Bow River.’ As the dinosaurian remains
were neither abundant nor well preserved, the country was not
again visited until 1906, when a party from the United States
Geological Survey, under the direction of Mr. A. C. Veatch, was
engaged in investigating the coal resources of the so-called Carbon
County coal-field. Veatch? published an outline geological map
on which was shown the areal distribution of the formations
involved. From this map it appeared that strictly speaking a
point ‘“‘opposite the mouth of the Medicine Bow River” would
fall within Veatch’s so-called ‘“‘Lower Laramie,’’* which is there
6,500 feet in thickness. Unfortunately Veatch did not collect
any dinosaurian remains and thus settle definitely their position
in this section, but from residents of the region who had known of
Hatcher’s discoveries it was pretty clearly indicated that they
came from a series of low bluffs about a mile up the North Platte
River from a point opposite the mouth of the Medicine Bow, in
beds belonging to Veatch’s so-called ‘‘Upper Laramie,’ which
are in part at least the equivalent of the ‘‘Ceratops beds”’ of Con-
verse County. The question of the absolute stratigraphic posi-
tion of these dinosaur-bearing beds was thus held in abeyance until
the past season (1910), when Dr. A. C. Peale and the writer spent
ten days in the region, during which we secured data which settled

t Am. Nat., XXX (1806), 118.

2U.S. Geol. Surv., Bull. 316 (1907), 244, Pl. XIV.

3 The “Lower Laramie” of Veatch is the same as the Laramie of the Denver
Basin of Colorado as shown by its stratigraphic position and contained fossils. See
Veatch, Jour. Geol., XV (1907), 526-49.

360 F. H. KNOWLTON

the matter definitely. Incidentally it may be mentioned that we
were able to confirm in every particular Veatch’s mapping of the
formations in this vicinity.

On the west side of the North Platte River, opposite the mouth
of the Medicine Bow River, the bluff in the ‘‘Laramie”’ is about
a mile back from the river. The beds, which consist of alternations
of soft shales and beds of shaly brownish sandstones and numer-
ous thin beds of coal, dip to the southeast at angles between 20°
and 25°. From the bluff the surface slopes gently to the stream,
and exhibits admirable exposures throughout. A very careful
search was made of the ‘‘Lower Laramie”’ section, and although
invertebrates pronounced by Dr. Stanton to be of ‘‘Laramie”’
age were found at numerous horizons, not a scrap of bone could
be detected.

The contact between the ‘‘Lower Laramie” and ‘‘ Upper Lara-
mie’’ is very distinct and undoubtedly has been correctly placed
by, Veatch. There is a distinct change in the dip, apparently
a slight change in the strike, and a marked change in the lithology
between the lower and upper beds. The basal 300-400 feet of
the beds above the line are composed of somber-colored soft sand-
stones and shales, often cross-bedded, with occasional small iron-
stone concretions, and in every way suggest the ‘‘Ceratops beds”’
to the northeast. Fragments of bone are scattered over the
surface, and although no large pieces were secured at this particular
point, enough was found to prove the presence of turtles, croco-
diles, and dinosaurs. On the strike of these beds at a point about
six miles southeast (T23N, R84W) we found in place about
300 feet above the base of the ‘‘Upper Laramie” beds a number
of large vertebrae. These have been studied by Mr. C. W. Gil-
more of the U.S. National Museum, and Mr. Barnum Brown of
the American Museum of Natural History, and by both pro-
nounced unqualifiedly to belong to Triceratops. It is not possible
to fix with certainty the species to which these vertebrae belong,
since the characters separating the species are drawn mainly from
the skull, but Mr. Gilmore permits me to say that it is impossible
to distinguish them from vertebrae of certain species from Con-
verse County in which both skull and vertebrae are known. It

STRATIGRAPHIC POSITION OF LANCE FORMATION 361

is quite possible that the skull of the individual of which we secured
the vertebrae could be recovered by more extended excavation than
we were able to make with the implements at hand.

Since, with the exception of their occurrence in the post-Lara-
mie formations of the Denver Basin, the remains of Triceratops
have never been found outside the Lance formation, the finding
of Triceratops at this point is of far-reaching importance. It
shows that not only are the beds containing them above more than
6,000 feet of ‘‘Laramie”’ rocks (the basal portion of which is almost
certainly of Fox Hills age), but also that they are separated from
the ‘‘Laramie”’ (“Lower Laramie’’) by an unconformity, which,
according to Veatch,’ is profound and has involved the removal
of perhaps as much as 20,000 feet of sediments. This would seem
effectively to dispose of the contention that the Lance formation
(‘‘Ceratops beds’’) is the equivalent of the Laramie.

The Lance formation—for such it must now be called—along
the North Platte River above (south of) the mouth of the Medicine
Bow, passes virtually without known stratigraphic break into
beds which some twenty-five miles to the south have yielded Fort
Union flora, thus showing the similarity of this section with all
other known sections in which both Lance formation and Fort
Union are present.

About 25 feet below the horizon of the Triceratops vertebrae,
in the area under discussion, we collected the following species of
plants:

Sabal grandifolia? Newb.
Populus amblyrhyncha Ward
Viburnum marginatum Lesq.
Sapindus sp.

Sassafras? sp. (Same as an unnamed species from the ‘‘Ceratops beds”
of Converse County, Wyo.)

The palm, which is identified with some doubt as Sabal grandt-
folia, has a longer rachis than is usual in this species but is other-
wise indistinguishable. It was described originally from the
Fort Union near the mouth of the Yellowstone, and has been found
subsequently at many localities in Montana, Wyoming, and Colo-

t Am. Jour. Sct., XXIV (1907), 18.

362 F. H. KNOWLTON

rado. The Populus above mentioned has not been found out-
side the Fort Union. Viburnum marginatum was described first
from Black Buttes, Wyoming, and has since been found in many
places, among them several localities in the Lance formation of
the Dakotas. The form identified as Sassafras? is a peculiar leaf
and is apparently the same as an unnamed form from the Lance
formation of Converse County. This analysis shows that three
of the five forms noted in this collection are found in the Lance
formation.

About five miles south of the above-mentioned Tviceratops
locality the ‘‘Upper Laramie”’ crosses the North Platte and the
exposures are excellent. At this point the “‘Upper Laramie”’
consists of a great thickness of massive beds of yellowish and
whitish sandstone, with much cross-bedding and abrupt changes
from one color to another. Several hundred feet above the exposed
base of this section we obtained a small collection of plants which
embraces some three or four species, all of which are identical with
undescribed forms from the Lance formation of Montana and the
Dakotas.

The evidence of the plants is thus seen to confirm that of the
vertebrates in correlating these beds with the Lance formation
of Converse County and other areas in Montana and the Dakotas.

THE OLD STANDING ROCK AND CHEYENNE RIVER INDIAN
RESERVATIONS

On the west side of the Missouri River, and lying between the
Cannonball River on the north and the Cheyenne River on the
south, is the area comprising in large part what was originally
within the Standing Rock and Cheyenne River Indian Reservations.
During the spring and early summer of 1909 this region was studied
by a number of parties from the U.S. Geological Survey under the
general charge of Mr. W. R. Calvert. The geology of this area
is comparatively simple, the rocks being very little disturbed and
at most comprising not more than four formations. Beginning
with the lowest these are the Pierre shale, which is exposed in the
valleys of most of the streams, and is overlain without strati-
graphic break by the Fox Hills, which is the highest marine forma-

STRATIGRAPHIC POSITION OF LANCE FORMATION 363

tion in the section. Above the Fox Hills, but, as will be shown
later, with the intervention in places of a distinct unconformity,
comes the Lance formation, above which, but without unconformity
or other observed break, is the acknowledged Fort Union.

In the present connection the principal interest naturally centers
in the Lance formation, and more particularly as regards its rela-
tion with the underlying Fox Hills. Mr. Calvert, who is not only
familiar with the area in question but with adjacent areas in North
Dakota and Montana where similar conditions obtain, has kindly
prepared the following statement:

“Stratigraphic work by field parties in immediate charge of
A. L. Beekly, Max A. Pishel, and V. H. Barnett in the Standing
Rock and Cheyenne River Indian Reservations of North and
South Dakota in tgog and similar investigation in eastern Mon-
tana in 1910 in charge of Max A. Pishel and C. F. Bowen gave
opportunity to study the relationship of several formations con-
cerning which discussion has arisen periodically for a number of
years, and which is of special interest in view of its direct con-
nection with geologic history at the close of the Cretaceous. The
region studied in the Dakotas includes the type locality of the
Fox Hills sandstone and is adjacent to the type locality for the
Pierre shale. Where the full section of the Fox Hills is present it
usually comprises a gradation at the base from the somber shale of
the typical Pierre into a more or less massive sandstone. This sand-
stone member is overlain by 25 feet or more of banded shale over-
lain in turn by a massive sandstone, constituting what in the field
was considered the top member of the Fox Hills. Fossils occur only
sparingly in the lower sandstone and in the banded shale, whereas
the top sandstone is prolifically fossiliferous, the fossils being found
most abundantly at or near the top of that member. Normally
overlying this fossiliferous horizon is a sequence of beds entirely
dissimilar in lithology from the underlying Fox Hills, and it is
concerning these beds that question has arisen relative to their
exact position in the geologic column. These strata constitute
the Lance formation to which the name ‘somber beds’ has been
applied in various previous publications.

“From the standpoint of lithologic character the term ‘somber

364 F. H. KNOWLTON

beds’ is very applicable, as the strata are made up chiefly of gray
to dark clays and muds with intercalated lenticular sandstone
members. There is rapid horizontal alteration in character of
material so that a section measured at any one locality does not
compare in detail with one measured a short distance away. Car-
bonaceous zones occur at frequent vertical intervals and the lowest
few feet of the formation is almost invariably a lignitic zone.

‘“As a result of field study by Pishel, Barnett, and the writer,
it seems certain that the line between the Fox Hills sandstone and
the Lance formation is marked by an unconformity, but the import
of that unconformity is of course a matter for the paleontologist
rather than for the stratigrapher to decide. However, the evi-
dence gathered by the stratigrapher may possibly have some weight
in arriving at a conclusion, and that evidence is here presented.

‘“The maximum thickness of the Fox Hills sandstone is in the
neighborhood of 200 feet, but it was found in the field that this
measurement is entirely too great for certain localities. On
Worthless Creek, in T16N, R2oE, Black Hills Meridian, exposures —
are especially good and it was here that the most striking
example of unconformity between the Fox Hills and Lance forma-
tion was observed. On the west side of Worthless Creek Valley,
near the line between sections 25 and 26, it was noted that the
‘somber beds’ of the Lance formation transgressed across the Fox
Hills sandstone and that the upper part of the latter formation
down to the banded shale member was absent. The unconformity
at this locality is angular as well as erosional, for the banded shale
dips to the north at a 4-degree angle, whereas the ‘somber beds’
are horizontal. Within a horizontal distance of 500 feet the
‘somber beds’ fill a channel eroded in the banded shale of the Fox
Hills, so that the total vertical amount of combined transgression
and erosion is more than 4o feet. On the opposite side of the valley
the total thickness of undoubted Fox Hills is even less, for it
appears that the lignitic zone of the ‘somber beds’ rests on Pierre
shale. In any event there is surely less than 25 feet of the Fox
Hills present at this place. In view of the fact that the Fox Hills
sandstone is normally at least 150 feet thick it would seem that

STRATIGRAPHIC POSITION OF LANCE FORMATION 365

the erosion interval represented is of considerable magnitude, or
else that the formation is peculiarly variable in thickness.

“In general the zone along the contact between the Fox Hills
sandstone and the Lance formation is poorly exposed in this region,
but in the majority of localities where exposures were adequate
careful study disclosed evidence that deposition was not continuous
from one formation into the other. In a paper’ on this subject
Doctor Stanton admits the occurrence of an unconformity at this
horizon in the Dakotas but attaches no particular significance
thereto, stating that channeling would normally be expected in
the change from marine to land conditions and giving especial
weight to the fact that a marine Fox Hills fauna is found com-
mingled with brackish-water types above the unconformity. He
states that ‘The paleontologic evidence consists of distinctive
Fox Hills species belonging to such marine genera as Scaphites,
Lunatia, and Tancredia, found directly associated in the same
bed with the brackish-water forms and occurring with them in
such a way that they must have lived together or near each other
and been imbedded at the same time.’

“From the above quotation the inference is plain that Dr.
Stanton concludes that the faunal evidence demonstrates with a
fair degree of certainty that the unconformity is of minor rather
than of major significance. To this conclusion the stratigrapher,
is, of course, not qualified to object with authority, but it seems
to the writer that the evidence may be looked at from two diver-
gent points of view. Because Fox Hills fossils occur in the lignitic
shales at the base of the ‘somber beds’ and mingled with the
brackish water types of the Lance formation is not necessarily
proof positive that the various faunas lived at the same time; for if
the deposition of the Fox Hills was followed by a definite erosion
interval, what is more probable than that in the deposition of suc-
ceeding strata fossil shells would be eroded from the marine beds
and carried into channels, there to mingle with the then living
brackish-water fauna of the Lance formation ?

1T. W. Stanton, ‘‘Fox Hills Sandstone and Lance Formation (‘Ceratops Beds’)
in South Dakota, North Dakota and Eastern Wyoming,” Am. Jour. Sci., XXX
(1910), 178.

366 F. H. KNOWLTON

“That the unconformity at this critical horizon is of more than
local significance is borne out in large measure by observations
made in the course of an examination of the lignite region in east-
ern Montana in ro1o. Trending southeast from Yellowstone
River, 10 miles southwest of Glendive, is an anticline which extends
to the South Dakota line and along which the Lance formation is
exposed in a zone on either side. Along the axis of this anticline
Pierre shale is at the surface in a band several miles in width with
a sandstone formation appearing as a zone of outcrop between it
and the Lance. Although fossils have not been found in this
sandstone it is believed to be the equivalent of the Fox Hills in

Fic. 1.—South bank Moreau River, near Govert P.O., South Dakota, showing
angular unconformity between Lance and underlying beds identified as Fox Hills.
Photograph by Barnett.

its type locality. Transition into it from the Pierre shale is perfect,
and as in the Dakotas it is overlain by the markedly dissimilar
strata composed of alternating lenticular sandstone, somber clays,
and carbonaceous zones. In at least two localities in this region
the upper surface of the sandstone referred to the Fox Hills is
irregular and with every appearance that sedimentation between
that formation and the overlying Lance formation was interrupted.
These were noted and mapped by Pishel and Bowen and are in
Sec. 22, TON, Rook, Sec. 32; T7N, RorR> Dhe-amountvor
erosion is not great in either case, but in the opinion of the
writer the occurrence of an unconformity in this region at appar-

STRATIGRAPHIC POSITION OF LANCE FORMATION 367

ently the same horizon as that in the Dakotas tends to show that
the break has more than local significance.”

The observations recorded by Mr. Calvert in the eastern portion
of this South Dakota field were supplemented and extended to the
western part of the state by Mr. V. H. Barnett in 1910, while
making a hasty reconnaissance trip across the country. For
instance, on the south bank of the Moreau River, near Govert P.O.,
in Sec. 21, Tr5N, R8E, South Dakota, Mr. Barnett found what
is perhaps the most marked evidence yet recorded of unconform-
able relations between beds thought to be Fox Hills and the Lance
formation. Mr. Barnett traced the Lance formation continuously
from the central part of the state to the point mentioned above,
where it was found practically horizontal, while the underlying
beds dip to the northwest at an angle of about 10°. These under-
lying beds appear to be in the stratigraphic position of, and litho-
logically similar to, beds resting immediately on Pierre shale, at
Hoover, about 1o miles southwest, and there is no reasonable doubt
regarding their age, but no paleontologic evidence was secured—
or sought—at this locality. If the beds are not of Fox Hills age
they must be older, which would indicate an unconformity of even
greater magnitude than is presumed. Mr. Barnett secured a
photograph of this section which he has kindly permitted me to
reproduce here as Fig. 1. The full section of the supposed Fox
Hills is not exposed at this point, but some distance west, at Castle
Rock Butte (T12N., R5E), the following section was measured;
Pierre 50 feet; Fox Hills 125 feet; Lance formation 140 feet, the
latter overlain by higher Tertiary.

The unconformity spoken of above by Calvert as occurring
in Sec. 32, T7N, RO61rE, in Custer County, Montana, is on the
west side of the anticline extending southeast from Glendive. It
is clearly shown in the accompanying Figs. 2, 3, the negatives
of which were made by Mr. C. F. Bowen, by whose consent they
are included here. The Fox Hills with a thickness of about
70 feet dips at an angle of 5°, while the overlying Lance formation
is horizontal.

Mr. Calvert’s observations concerning the occurrence of the
marine Fox Hills invertebrates in the basal members of the Lance

368 F, H. KNOWLTON

formation may be briefly alluded to. It appears that in the
hundreds of localities throughout the Dakotas, Wyoming, and
Montana at which the contact between Fox Hills and the Lance

Fics. 2, 3.—Eastern part of Custer County, Montana, showing erosional uncon-
formity between Fox Hills and Lance. Photographs by Bowen.

formation has been examined, only five localities, all within a
limited area in South Dakota, have been noted in which the marine
Fox Hills invertebrates occur above the acknowledged top of the
Fox Hills, where they are often found commingled with certain

STRATIGRAPHIC POSITION OF LANCE FORMATION 369

brackish-water forms. It does not appear that they have ever
been found at a greater distance than 12 or 15 feet above the top
of the Fox Hills, and since it further appears that in none of the
four sections given’ does the Fox Hills exceed 115 feet in thickness,
there is every probability that they were re-deposited in the chan-
neled upper surface of the Fox Hills and that they did not live in
association with the brackish-water forms with which they are now
found entombed.

The plant collections obtained from the Lance formation by
Mr. Calvert and the members of the several parties under his
charge show conclusively that the relation of this flora is unmis-
takably with the Fort Union. In fact with the information at
hand regarding distribution it is practically impossible without
stratigraphic data to distinguish between the flora of the Lance
formation and that of the acknowledged Fort Union. The lists
of these collections follow:

[5437]. NW ¢ Sec. 5, T2N, R88W, S. Dakota. North bank of Cannonball
River, at McCord coal-bank, 150 feet above base of beds.
Sequoia nordenskiéldi Heer
Thuya interrupta Newb.
Glyptostrobus europaeus Unger
Populus speciosa Newb.
Populus amblyrhyncha Ward
Paliurus colombi? Heer
Sapindus grandifoliolus Ward
Celastrus alnifolia ? Ward
Juglans sp. ?
2 new forms, gen. ?

[5443]. SW % Sec. 23, T23N, Ra1E, Black Hills Meridian, 150 feet above base

of beds. Sequoia nordenskidldi Heer

Leguminosites arachnioides Lesq.
[5444]. Near { cor. E. side Sec. 13, T22N, R22E. Black Hills Meridian. 125
feet above base of beds.
2 or 3 of same species as unnamed forms from the ‘‘somber beds”’ at
Glendive, Montana.
[5430]. Rattlesnake Butte, Cheyenne Indian Reservation, S. Dakota. 100
feet above base of beds.
Glyptostrobus europaeus Newb.
Taxodium occidentale Newb.

tAm. Jour. Sct., XXX (1910), 174-77.

[5422].

[5431].

[5432].

[5433].

[5434].

[5436].

F. H. KNOWLTON

Viburnum marginatum Lesq.

Cornus newberryi Hollick

Salix sp.

Quercus sp.

3 or 4 forms that are identical with unnamed species
from Glendive, Montana.

Near SE + Sec. 20, T14N, R1oE, Black Hills Meridian, S. Dakota.
100 feet or less above base of beds.
Sequoia nordenskidldi ? Heer
Sequoia langsdorfii Heer
Platanus platanoides ? (Lesq.) Kn.
Viburnum sp. (same as new species from Lance of
Converse County, Wyoming).
Lauraceous leaf (same as form found in “somber
beds” at Glendive, Montana).

SW i Sec. 4, TroN, R18E, S. Dakota. 300 feet above base of beds.
Thuya interrupta Newb.
Populus amblyrhyncha ? Ward
Viburnum elongatum Ward
Viburnum sp. ?
Grewiopsis whitei ? Ward
SE } Sec. 25, T20oN, R18E,S. Dakota. 300 feet above base of beds.
Sequoia nordenskidldi ? Heer
Zizyphus cf. Z. hyperboreus Heer
Populus ? sp.
Platanus ? sp.
Sec. 33, T20N, R20E, S. Dakota. 150 feet above base of beds.
Ginkgo adiantoides Heer
Platanus raynoldsii ? Newb.
Sapindus grandifoliolus ? Ward
Viburnum (apparently same as unnamed species
from Lance of Converse County, Wyoming).

SE + Sec. 12, Tr9oN, R24E, S. Dakota. Base of beds.
3 fragmentary leaves, apparently same horizon as No. 5436.

NE cor. Sec. 7, T17N, R24E, S. Dakota. Base of beds.
Platanus haydenii Newb.
Viburnum elongatum Ward
Viburnum marginatum ? Lesq.
Sapindus grandifoliolus ? Ward
Dombeyopsis sp.
Polygonum ? sp.
Lauraceous leaf like that of Glendive, Montana
2 species same as unnamed form from Glendive

STRATIGRAPHIC POSITION OF LANCE FORMATION 371

[5423]. South of Moreau River about 7 miles above Thunder Butte P.O.,
S. Dakota.
Sec. 35, T14N, R1oE. Lower 4 feet of Lance formation.
Thuya interrupta Newb.
Sequoia nordenskidldi Heer
Sequoia acuminata ? Lesq.
Populus cuneata Newb.
Viburnum marginatum ? Lesq.
Leguminosites ? n. sp.
Cyperacites sp.
Monocotyledon—new

It needs but a glance at the above lists to show how preponder-
ating is the Fort Union facies.

CONVERSE COUNTY, WYOMING

Although Converse County, Wyoming, is the type locality for
the Lance formation, and has been visited again and again by
geologists and paleontologists, it is still a perennial source of dis-
cussion and difference of opinion. From the first, difficulty has
been experienced in drawing the line between the highest marine
formation—the Fox Hills—and the overlying dinosaur-bearing
beds. The Fox Hills was estimated by Hatcher to have a thickness
of 500 feet, and consists of an alternating series of sandstones and
shales, with massive sandstones at the top which contain numer-
ous large concretions and a rich marine fauna of characteristic
Fox Hills species. The upper line was drawn somewhat arbitrarily
at a six-inch band of hard sandstone which was thought to separate
the fossil-bearing Fox Hills sandstone below from similar but sup-
posedly non-fossiliferous sandstones above. When Dr. Stanton
and I visited this region in 1896 we failed to secure evidence for
changing the top line of the Fox Hills as established by Hatcher,
though we did find four species of brackish-water invertebrates
in clays above a forty-foot bed of massive sandstone over 400 feet
above the highest fossiliferous Fox Hills horizon in that particular
section.

So the question rested until 1909, when Messrs. M. R. Camp-
bell, T. W. Stanton, and R. W. Stone spent nearly a week in the
region. Their principal contribution to the knowledge of the

272 F. H. KNOWLTON

TCG;

stratigraphy of the area was, according to Stanton,’ “the discovery
that the marine Fox Hills deposits extend about 4oo feet higher
than had previously been determined, and that non-marine coal-
forming conditions were temporarily inaugurated here before the
close of Fox Hills time.’ If Hatcher’s estimate of the thick-
ness of the beds assigned by him to the Fox Hills was anywhere
near correct this ‘discovery’? would seem to increase the total
thickness to about goo feet, yet nowhere in the paper mentioned
is a thickness greater than 400 or 500 feet claimed for it. This
appears difficult to explain unless the lower as well as the upper
limit of the formation has been changed.

A number of sections are given by Dr. Stanton, in one of which
at least, namely that on Buck Creek, the top of the Fox Hills
appears to have been fixed by the presence of the plant Halymenttes
major. ‘The thickness of the Fox Hills in this section is given as
505 feet, though the highest horizon at which marine Fox Hills
invertebrates occur is about 180 feet below the top.

In the section made on the divide between Lance and Buck
Creeks the Fox Hills is said to have a thickness of 445 feet, though
the lower member of the section only (30 feet above the Pierre
shale) is indicated as containing a Fox Hills fauna.

The section made on the south side of the Cheyenne River at
the mouth of Lance Creek shows a thickness of 405 feet of Fox
Hills above the Pierre, but the highest point in the section at which
marine Fox Hills invertebrates were found is over too feet below
the top. It further appears from this section that the upper four
members, aggregating 115 feet in thickness, contain carbonaceous
and lignitic shales as well as fragments of dinosaur bone and
brackish-water invertebrates, certain of which are the same as those
found in, and there said to indicate the Laramie age of, the 400
feet of beds already mentioned as reported by Stanton and Knowl-
ton above the typical marine Fox Hills.2, To the writer it seems
altogether more probable that the four upper members of this
section belong to the Lance formation and not to the Fox Hills,
and it appears that this was the view at first entertained by Dr.

t Am. Jour. Sci., XXX (1910), 184.

2 Bull. Geol. Soc. Am., VIII (1897), 130.

STRATIGRAPHIC POSITION OF LANCE FORMATION 373

Stanton, who says,’ ‘‘When studying the section it was believed
that the upper four members belong to the Lance formation, but
afterward when comparison was made with sections of the south
end of the field it seemed more possible that all the beds examined
here belong to the Fox Hills.”’ If this portion of the section is
placed in the Lance formation, where it certainly appears to belong,
the thickness of the Fox Hills in the section is reduced to 285 feet,
or but little more than half of the maximum thickness assigned
to beds of this age in the Converse County region. While this
evidence may not be considered conclusive, it must at least be
admitted that it strongly suggests the possibility that even here,
as in the areas already discussed in the Dakotas and Montana,
the Fox Hills is of variable thickness, due to the erosion of the upper
portions before the deposition of the Lance formation.

It is to be admitted, however, that all who have studied the
Converse County areas have had, and still have, difficulty in fixing
the upper line of the Fox Hills, but in this connection it is to be
pointed out that while many students have visited or collected
in the region, it still awaits the careful, painstaking study that has
been given other fields, such, for instance, as the areas in the
Dakotas and Eastern Montana, which have been described by
Mr. Calvert. And in this connection it may be mentioned that
although in Converse County the exact location and extent of the
unconformity between Fox Hills and Lance is not definitely known,
the time interval is undoubtedly indicated, since 150 miles to the
southeast (i.e., opposite the-mouth of the Medicine Bow River)
the same dinosaur-bearing beds are above an unconformity which
separates them from 6,000 feet of unquestioned “‘Laramie,”’ while
100 miles to the east in the Dakotas, the Lance formation rests
on an uneven surface which in some cases represents the removal
of practically the whole thickness of the Fox Hills of the region.

As a possible explanation of the difficulty experienced in detect-
ing the presence of the unconformity between the Fox Hills and
overlying Lance formation in this area, the following facts may
be offered: the localities in Eastern Montana and Western South
Dakota where the examples of the distinct angular and erosional

tAm. Jour. Sci., XXX (1910), 185.

374 F. H. KNOWLTON

unconformity are so well exhibited are all adjacent to the anti-
clinal uplift which Calvert has shown extends southeast from the
vicinity of Glendive, Montana, to the western line of the Dakotas.
Here the uplift tilted the beds and accelerated the erosion, while
in the flat country to the westward in Converse County and adja-
cent areas, the erosion of the Fox Hills was relatively uniform, and
when the Lance formation was later laid down over this surface
the unconformable relations are difficult of detection. But as
Cross long ago stated: ‘‘The visible conformity between the Cera-
tops beds and Fox Hills in Converse County cannot be accepted,
contrary to other evidence, as proving the former to have been
deposited in the epoch next succeeding the Fox Hills.”’

UPPER LIMIT OF.THE LANCE FORMATION

In my original paper on the Lance formation (‘‘Ceratops beds’’)
I stated that everywhere throughout the vast region studied it
was found conformably overlain by the acknowledged ‘‘yellow”’
Fort Union, adding that ‘‘of the many workers who have observed
the field relations at hundreds of points, not one, so far as known
to the writer, has recorded the presence of unconformity between
them.’ Field work during the past two seasons has confirmed
this statement in every particular, and there is yet to be observed
a single locality at which unconformable relations have been even
suspected. Hence it seems to have been demonstrated that
sedimentation from one to the other was continuous and unin-
terrupted. :

At the time the original paper was published it was thought
that the Lance formation and the acknowledged Fort Union (the
lower and upper members of the Fort Union as they were there
called) might usually be separated on lithologic grounds, the lower
being generally dark and somber-colored and the upper usually
yellow. Subsequent investigation, however, has failed to confirm
this, for while in individual sections, or even within limited areas,
a provisional lithologic separation may often be made, when
regional studies were undertaken it was found that the lithologic
difference was so variable within short distances as to be wholly

t U.S. Geol. Survey, Mon. 27 (18096), 236.

STRATIGRAPHIC POSITION OF LANCE FORMATION 375

unreliable. For instance when a coal-bed that occurred near the
top of the so-called somber-colored Lance formation was traced
accurately for only a few miles it was found that the position of
the dark-colored and the yellow beds varied as much as 300 feet,
that is, at one point, the coal-bed might be 150 feet down in the
somber-colored portion, and at another, an equal distance up in
the yellow beds. It may therefore be confidently stated that the
Lance formation and acknowledged Fort Union cannot be sepa-
rated formationally on either structural or lithologic grounds,
though in general the lower beds are on the whole prevailingly
somber in color, while the upper beds are prevailingly yellow.

MAGNITUDE OF UNCONFORMITY AND BOUNDARY BETWEEN
CRETACEOUS AND TERTIARY

Having demonstrated the existence of unconformable relations
between the Lance formation and the underlying formations, the
question naturally arises as to the magnitude of this discordance.
By some it is claimed that it is merely local and is not more impor-
tant than other breaks said to occur at various intervals in the
Lance formation, and the doubt is expressed whether, even if the
unconformity is present, any great amount of erosion is indicated.

The wide area over which its existence has now been demon-
strated certainly removes it from the category of ‘local’? happen-
ings, and the uniformity of its occurrence beneath the Lance forma-
tion is sufficient indication of its Importance over any that have
been thus far even apparently indicated within the formation.
Now as to its magnitude. It has been shown that in Carbon
County, Wyoming, the Lance formation is not only above the full
thickness of the ‘‘Laramie”’ (6,000 feet) but is separated from it
by an unconformity that Veatch states is fully 20,000 feet, and
moreover this unconformity is in the same position as regards the
Laramie as that in the Denver Basin of Colorado, which, accord-
"ing to Cross, has involved the removal of from 12,000 to 15,000
feet of strata between the Laramie and overlying formations.
It is possible that the figures given by Cross and Veatch may be
too high, but even so, the unconformity is undoubtedly one of
importance, and this would seem to dispose of the contention that

376 F, H. KNOWLTON

the Lance, Arapahoe and Denver formations may be mere “phases
of the Laramie.’’ Whether the Laramie and various post-Laramie
beds were deposited and later removed throughout the Dakotas,
Montana, and Wyoming, is not at present known, but certain
it is that the unconformity at the base of the Lance formation
represents the time interval during which in other areas they were
laid down and subsequently removed in whole or in part. There-
fore, in the opinion of the writer, this unconformity is an impor-
tant one and must be so recognized in American geology.

Since it has been demonstrated that the Lance formation is so
inseparably associated with the Fort Union—that is, without a
trace of an unconformity—and is separated from the underlying
formations by an unconformity of such extent, this point becomes
more clearly than ever the logical point at which to draw the line
between Cretaceous and Tertiary. In establishing this line the
stratigraphic, lithologic, and paleobotanical criteria are believed
to be more competent than any other evidence thus far brought
forward.

LARGE GLACIAL BOWLDERS

GEORGE D. HUBBARD
Oberlin College

Mention of large glacial bowlders is not uncommon. In fact
most localities glaciated have their ‘“‘largest in the state.’”’ Some
lie so as to reveal easily the fact that they have been transported.
Others are more or less concealed, and some care is needed to
determine whether the rock is really a transported mass or country
rock in place.

A mass of limestone in Ohio covering about three-quarters of
an acre, and in places sixteen feet or more in thickness, was men-
tioned by Orton in one of the older reports of Ohio geology and
cited by Dana.’ In the Alps was found a mass containing about
200,000 cubic feet of rock or enough to cover a fourth of an acre
twenty feet deep.?, Sardeson’ reports a block of limestone moved
a short distance whose width was over roo feet, thickness several
feet, and length unknown. Limestone bowlders, often large
masses, are quite common in parts of Illinois, specifically in western
Livingston County, in northern McLean, and in parts of Cham-
paign, Ford, and Vermilion counties. Following is a detailed
description of several masses or “‘pockets”’ of this rock which have
been studied.

On the south side of the Champaign-Ford county line one and
one-half miles east of the northwest corner of Ludlow township
are the remains of a large “pocket.” H. H. Atwood of Paxton
who owns the farm says several loads of the rock have been drawn
away for building purposes, but enough remains to mark the place
distinctly.

Near Saybrook, McLean County, are a number of localities
where limestone is found at the surface. On the farm of Mr. Riggs,

tJ. D. Dana, Manual of Geology, 5th ed. (1895), 960.

2 Thid., 248.

3 Jour. Geol. (1905), XIII, 351-57.

377

378 GEORGE D. HUBBARD

one mile north and one and one-half miles west of Saybrook, lime
was burned forty or fifty years ago. A small kiln was built and
operated several years with rock from this deposit. A half-mile
east of this kiln, past the schoolhouse, another ‘‘pocket”’ was
opened and several loads drawn some thirty-five years ago. At
present but few know of these limestone pits, for they have been
entirely dug out and the holes are plowed over. Portions of the
kilns and fragments of waste alone remain.

Two miles north and one mile west from Saybrook are a number
of slabs resembling flagging. These are quite numerous on one
farm. On a farm ten miles west of Saybrook lime was burned for
the local market, but at present the rock is apparently exhausted.
In this locality, a good many loads for foundations and well curbs
have also been drawn away. According to a boring for Mr. H.
Cheney of Saybrook, bed rock was struck here at a depth of 236
feet. It is recorded that a five-foot limestone bowlder was struck
in a gravel bed at a depth of 150 feet. A well digger here in con-
versation said that in digging wells he frequently encountered
limestone bowlders of various sizes, and noted several localities
where the bowlder weighed from ten to twenty tons. A number
of wells in the vicinity have been walled with the rock taken out
in digging, supplemented with more found near by. “In fact,”
he says, ‘‘there is lots of limestone scattered all over the country.”
No bed rock, however, has ever been found about Saybrook except
at considerable depths as in the well cited, 236 feet.1 With
such thickness of drift as this, these masses of limestone cannot
be in place.

The largest drift mass of limestone is in Livingston County,
about a mile and a half southwest of Fairbury, where Dr. Brewer
has been taking out a great deal of limestone. The mass is along
a small stream where the water divides, flowing around a little
island. On the north bank of the south division and on both
banks of the north division, rock is found; but on the extreme
south bank no rock is known, nor is rock struck in any wells on the
south side of the stream. Along the stream on the north side for

t Frank Leverett, U.S.G.S. Mon. 38, 695, reports a boring for coal here reaching
rock at 247 feet.

LARGE GLACIAL BOWLDERS 370

a half-mile or more, and back from the stream a half-mile, all wells
strike rock at some twelve to sixteen feet. Below the rock at the quarry
is Clay, a soft sticky yellow body, called by the quarrymen ‘‘soap-
stone.” Examination showed it to be glacial drift. No large
pieces of rock can be obtained in the quarry, for the whole mass
is shattered. The pieces vary in size from ten or fifteen to two
hundred and fifty pounds, rarely larger than can be handled by
one man. At the quarry the rock is from ten to fifteen feet thick,
and two or three nearby wells are reported passing through it,
one finding sixteen feet of rock.

The rock seems to be almost exactly horizontal in the quarry,
and it is struck at quite uniform depths in the neighboring wells.
Inquiry for this stratum in the coal shafts, two in number, at
Fairbury, failed to reveal its presence. One about a mile distant
encountered a piece of rock at a depth of forty feet, but below it
was more clay. The other about one and one-quarter miles
distant found no rock for at least ninety feet.

At McDowell a little quarry is operated in rock which has
almost precisely the same characters as the one at Fairbury,
but it is of less extent—ten or twelve feet thick, shattered and
local. West and south of McDowell about two miles from Ocoya
there are two or three little quarries opened. One near a little
stream is operated by two men who have taken out over a hundred
cords of rock in a single summer. The rock is eighteen feet thick
at a maximum, but in places only five or six feet thick. Some
parts of it are shelly or shattered, but toward the bottom, this
mass is firmer than any other yet considered. Sometimes pieces
twelve to sixteen inches thick and six to eight feet long are removed,
but no blasting is done. The near proximity to the stream caused
some trouble with water seepage, so a sumpf was dug through
the rock and a pump put in. A crowbar was thrust down easily ©
in the bottom of this sumpf two or three feet. The quarrymen say
the substratum is ‘“‘soapstone of variable character,” but it seems
to be a well-packed, blue, pebbly clay with a greasy feel. That
it is not one of the soft argillaceous layers of the Coal Measure
rocks is shown by its pebbles. The edge of the rock is known
in two directions. The edge along the stream is slanting, the other,

380 GEORGE D. HUBBARD

nearly at right angles thereto and on the east end of the quarry,
is perpendicular and very regular. Rock is struck in but one
well in the vicinity. Rock has been taken out from similar, though
smaller local pockets, in two other localities within 80 rods.

The county surveyor of Livingston County says there are
a good many local deposits along the Vermilion River, slabs,
bowlders, and irregular pieces, but it is not continuous, and the
layers are variously tilted.

Usually these large masses are along morainal ridges. Some-
times they are found along stream beds where they have been
exposed by erosion. They cover areas varying from a few rods
to over a hundred acres in extent, and differ in thickness from six
or eight feet to eighteen or twenty feet. They are always in a
shattered condition; often very much broken up, but sometines
requiring some blasting to get out the rock. What seems the most
surprising thing is that there is rarely much dip. The bedding
in all the larger masses is almost horizontal. During early days
when transportation was expensive, these masses of limestone
were much used by the settlers, who made lime from some of them,
and from others drew building material. The rock was more
workable, and hence more desirable, than the granite bowlders.

Their presence in the drift, and their distribution mostly in
the large recessional moraines, seems to point to a glacial origin
for them. Since most if not all the masses mentioned are of
Carboniferous rock, as shown by their fossils, the sources could
not have been more than fifty to seventy-five miles north, for
beyond that limit there is no Carboniferous rock, from which they
could have come. While no specific places have been found from
which it is thought these large bowlders were plucked, it is believed
that they may have come readily from the bluffs of a valley, or
from hills a moderate distance to the north.

REVIEWS

Tron Ores, Fuels and Fluxes of the Birmingham District, Alabama.
By Ernest F. BURCHARD AND CHARLES Butts. With Chap-
ters on the “Origin of the Ores,” by Epwin C.Ecket. Bull.
U.S. Geol. Surv. No. 400. Pp. 204.

The Birmingham District, as here considered, extends as a long,
narrow belt, about seventy-five miles in length by ten in width. The
iron ores of the district lie in the broad, anticlinal Birmingham Valley
which is structurally a part of the Appalachian Valley. An outline
of the geology of the district shows rocks belonging to all the periods
from the Cambrian to the Pennsylvanian, with unconformities separating
all the systems except the Cambrian and the Ordovician, where the
transition is within the Knox Dolomite, which here attains a thickness
of 3,300 feet. An unconformity is found within the Ordovician. Within
the area are extensive deposits of red hematite and brown ore, and
important beds of coking coal and fluxing limestones.

The red hematite or Clinton ore is found in the Clinton or Rock-
wood formation which, in Alabama, consists of lenticular beds of sand-
stone and shale with four well-marked ore horizons. The ores occur
in lenticular beds analogous to strata, interbedded with limestone,
sandstone, and shale. Three opposing theories have been advanced
_to account for the origin of the Clinton ores: (1) original deposition;
(2) residual enrichment by weathering; (3) replacement by percolating
waters. Mr. Eckels shows that both the second and third theories are
untenable, and that observations support the theory of primary sedi-
mentary deposition.

The brown ores or ores of the hydrous iron oxides belong to a type
common in southeastern United States, occurring as irregular masses
associated with residual clays, and underlain by limestones of Cambrian
and Cambro-Ordovician age. Mr. Eckel points out very forcibly that
the decay of a limestone carrying disseminated iron material would
not of itself yield such a deposit of ore, but that some factor must be
found whereby the iron is concentrated. In his opinion, this concen-
tration usually took place in the limestone itself.

The coke used in the blast furnaces of the district is made from coal
mined in the Warrior coal field which lies to the northwest of the valley.

Re:
381

82 REVIEWS

Annual Report of the Geological Survey of Western Australia for
the Year tg09. By A. GipB MAITLAND, Government Geolo-
gist. Pp. 32, maps 4, andtigs.. 3:

The report contains a summary of the work done and the results
obtained by each of the fifteen officers employed by the survey. Three

bulletins were issued by the survey during the year tgo9: Bull. 33,

‘Geological Investigation in the Country Lying between 21 deg. 30

min. and 25 deg. 30 min. S. Lat. and 113 deg. 30 min. and 118 deg.

30 min. E. Long., Embracing Parts of the Gascoyne, Ashburton, and

West Pilbara Goldfields’; Bull. 35, “‘ Geological Report upon the Gold

and Copper Deposits of the Philips River Goldfield”; Bull. 37, “The

Geological Features of the Country Lying along the Route of the Pro-

posed Transcontinental Railway in Western Australia.”’
E.R. L.

“The Dakota-Permian Contact in Kansas.” By F. C. GREENE.
Kansas University Science Bulletin, Vol. V, No. 1 (October,
1909), pp. 1-8.

The paper presents a summary of the relations of the Permian and

the Cretaceous in Kansas, north of the Smoky Hill River.
eR les

Annual Report on the Mineral Production of Virginia during the
Calendar Year 1908. Virginia Geological Survey Bull. No.
I-A. By THomas LEONARD WATSON. Pp. 138.

Virginia possesses an abundance and variety of mineral materials,
about forty varieties of which are now exploited, many of them on a
large scale. A table of the mineral production in 1908 shows a total
value of nearly $18,000,000, of which iron makes up over $6,000,0c0.
Under the heading Preliminary Generalities, the author presents a
brief and interesting review of the physiography and general geology
of the state, including several generalized sections from various parts
of the state. The parts devoted to the various mineral deposits are
chiefly descriptive and statistical. A valuable feature of the report
is a series of maps showing the distribution in the state of a number of

the most important of the mineral deposits.
Ee Ree:

REVIEWS 383

Annual Report of the State Geologist, Geological Survey of New
Jersey, t909. By Henry B. Ktmmet, State Geologist.
EVO), ey.

Besides the administrative report this volume contains the following
papers: ‘Report upon the Development of the Passaic Watershed by
Small Storage Reservoirs,” by C. C. Vermeule; ‘Records of Wells in
New Jersey, 1905-9,” by Henry B. Kiimmel and Howard M. Poland;

“Notes on the Mineral Industry,” by Henry B. Kiimmel.
E.R. L.

‘““A Proposed Classification of Petroleum and Natural Gas Fields
Based on Structure.”” By FREDERICK G. CLAPP. Economic
Geology, Vol. V, No. 6 (September, 1910), pp. 503-21.

The classification proposed by the author of this paper is based on
the “anticlinal” or ‘structural’? theory, which is called into use to
explain the segregation of oil, water, and gas from a primary disseminated
condition. Depending on the structures which have segregated and
localized the pools, seven classes of oil and gas accumulations have
been distinguished by the author: I, Where anticlinal and synclinal
structure exists; II, Domes or quaquaversal structures; III, Sealed
faults; IV, Oil and gas sealed in by asphaltic deposits; V, Contact of
sedimentary and crystalline rocks; VI, Joint cracks; VII, Surrounding
volcanic vents. Class I embraces most of the known oil fields and is
subdivided into five subclasses to distinguish the various relations

of the pools with anticlines and synclines.
BeR. EL:

‘Outline Introduction to the Mineral Resources of Tennessee.”’
Extract (A) from Bulletin No. 2, Preliminary Papers on the
Mineral Resources of Tennessee, State Geological Survey. By
GEORGE H. ASHLEY, State Geologist. Pp. 65.

This pamphlet contains a brief survey of the surface features of the
state, the geological formations, and the geological history; and a list
of the minerals of the state with a brief notice of their occurrence, use,
etc. Bulletin No. 2, of which this is the first part to be published, is
the first scientific publication of the newly established state survey,
and is not intended as an original contribution but as a brief statement
of facts already published, and is designed to meet the demand for

immediate information on the mineral resources of the state.
HR:

384 REVIEWS

Summary Report of the Geological Survey Branch of the Department
of Mines, Canada, for the Calendar Year 1909. By R. W.
Brock, Directorsa-Pps 3078

Besides the administrative report of the director of the survey,
there is included in this volume a short summary report by each of the
geologists and officers of the survey, of the work carried out during the
year. Almost all of the work at present being undertaken is along

economic lines.
i Regs

“The Tectonic Lines of the Northern Part of the North American
Cordillera.’ By W. Jorrc. Bull. Am. Geog. Soc., XLII
(1910), 161-79. With map.

This paper pictures the tectonic lines of the North American Cor-
dillera from the 4oth parallel to Bering Sea. Though the author has
based his work in part upon the reports of the geological surveys of the
United States and Canada, he has confessedly followed Suess, in the
main, both in subject-matter and in mode of treatment. The chief
purpose of this paper is to consider in their larger relations the individual
ranges and groups of ranges which go to make up this complex system.
The interrelations of these mountain chains are discussed in a condensed
synoptical form. The axes of the many separate, individual ranges
are located on the map by heavy black-tectonic lines which show graphi-
cally the distribution and direction of deformative movements. A
prominent place is given to the mountain systems of Alaska.

In conclusion the author suggests the subdivision of the North
American Cordillera from Bering Sea to the Isthmus of Tehuantepec
into three major divisions: (1) Northern Cordillera, or Alaskides; (2)
Central Cordillera; (3) Southern Cordillera, or Lower California and
the Mexican Highland.

The boundary between the first and second divisions would be the
zone of coalescence near the Alaskan boundary, that between the second
and third the depression along Salton Sink, the Gila, and the Rio Grande.
The decided Asiatic structure of the Alaskides is the reason given for
recognizing them as an independent major subdivision of the Cordillera.

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VOLUME XIX é : ‘NUMBER 5

THE

JOURNAL or GEOLOGY

A SEMI- QUARTERLY

EDITED BY

THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
With the Active Collaboration of

SAMUEL W. WILLISTON ALBERT JOHANNSEN WILLIAM H. EMMONS
Vertebrate Paleontology Petrology i Economic Geology

STUART WELLER WALLACE W. ATWOOD ROLLIN T. CHAMBERLIN
Invertebrate Paleontology Physiography Dynamic Geology

ASSOCIATE EDITORS

SIR ARCHIBALD GEIKIE, Great Britain Z GROVE K. GILBERT, National Survey, Washington, D.C.
HEINRICH ROSENBUSCH, Germany CHARLES D. WALCOTT, Smithsonian Institution
THEODOR N. TSCHERNYSCHEW, Russia HENRY S. WILLIAMS, Cornell University

CHARLES BARROIS, France JOSEPH P.IDDINGS, Washington, D.C.

ALBRECHT PENCK, Germany JOHN C. BRANNER, Stanford University

HANS REUSCH, Norway RICHARD A. F. PENROSE, Jr., Philadelphia, Pa.
GERARD DEGEER, Sweden WILLIAM B. CLARK, Johns Hopkins University
ORVILLE A. DERBY, Brazil : WILLIAM H. HOBBS, University of Michigan

T. W. EDGEWORTH DAVID, Australia FRANK D. ADAMS, McGill University

BAILEY WILLIS, Argentine Republic CHARLES K. LEITH, University of Wisconsin

JULY-AUGUST, 1911

CONTENTS
SAMUEL CALVIN - hea eae Pea a oak ee eee lt POSTER BAIN aes
THE EVOLUTION OF LIMESTONE AND DOLOMITE. II - - Epwarp STeEmtTmMann 392
DIFFERENTIATION OF KEWEENAWAN DIABASES IN THE VICINITY OF LAKE
NIPIGON - - - - - - - - = Bee a ease as ic shee ete Oe LOORIAAZO
GENERA OF MISSISSIPPIAN LOOP-BEARING BRACHIOPODA = - - Stuart WELLER 439

PHYSIOGRAPHIC STUDIES IN THE SAN JUAN DISTRICT OF COLORADO
WALLACE W. ATWOOD 449

THE VARIATIONS OF GLACIERS. KVI - - - - - -.- - Harry Freipinc Rem 454
BE GEOnOGIOAL ABSERACKS AND BEVIRWS 9-02 20 POO as en ee
TRIS DENNY Sth go he teil et SY ls cates a ce ec aeRO COL Na pees aria Ryall Onin ara

Che Aniversity of Chicago press
CHICAGO, ILLINOIS
AGENTS:
THE CAMBRIDGE UNIVERSITY PRESS, Lonpon anp EDINBURGH {
WILLIAM WESLEY & SON, Lonpon
TH. STAUFFER, Leipzic
THE MARUZEN-KABUSHIKI-KAISHA, Tokyo, Osaxa, Kyoto

OUTLINES OF GEOLOGIC HISTORY

WITH ESPECIAL REFERENCE 10 NORTH AMERICA

A Series of Essays Involving a Discussion of Geologic Correla-

tion, Originally Presented before Section E of the American
Association for the Advancement of Science J* J c#

EOLOGISTS 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 correlation under the

title, OUTLINES OF GEOLOGIC HIsTORY wiTH ESPECIAL REFERENCE TO
NortH AmeERiIcA. The symposium was organized by Bailey Willis, and
the papers were originally presented before Section E of the American
Association for the Advancement of Science at Baltimore in December,
1908. They were first published by the Yournal of Geology and are
now brought out in book form under the editorship of Rollin D. Salisbury. —

The series as a whole represents the successful execution of the
plan on which. all the monographs were based—namely, to formulate
the principles of correlation as applied to the formations of the various
geologic periods. The evolution of floras and faunas has been traced
with especial attention to environment and correlation. As originally
presented, the papers excited much interest and discussion. They
embody the present state of knowledge and opinion concerning many
of the fundamental 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 paleo-
geographic maps by Bailey Willis which accompany the papers.

316 pages, 8vo, cloth; $1.66 postpaid

ADDRESS DEPARTMENT P

THE UNIVERSITY OF CHICAGO PRESS
CHICAGO, ILLINOIS

THE

JOURNAL OF GEOLOGY

Ve LNe AUGUST, LOU,

SAMUEL CALVIN

H. FOSTER BAIN

Samuel Calvin, who died at Iowa City, Iowa, April 17, 1911,
was born in Wigtonshire, Scotland, February 2, 1840. He passed
the first eleven years of his life in the little town of Wigton, living
the simple, hardy life common in Scotch families of moderate means.
As a boy, after school hours, he often paused at the edge of the
cliff to look down upon Wigton Bay in which lay ships and schoon-
ers from all parts of the world. At that period trade between
America and the various little ports on Solway Firth was active,
and the longing for travel, common to all boys, was greatly stimu-
lated in young Calvin by the sight of the vessels that came and went.
Among his school companions was James Wilson, now Secretary
of Agriculture, and a friendship was there formed that continued
through life. The Calvin and Wilson families both emigrated
to the United States in 1851, the Calvins going direct to Iowa and
the Wilsons following after a short sojourn in Connecticut. Thomas
Calvin, the father of Samuel Calvin, took up land south of Man-
chester, Iowa. At that time neighbors were few and far between
in eastern Iowa. The first residents came from Indiana and,
being accustomed to a wooded country, feared to venture upon
the open prairie. They accordingly settled near the streams on
what proved to be the poorer land. The Calvins and their asso-
ciates, evidently thinking that having ventured so much in coming
from Scotland they might as well venture more and save themselves
Vol. XIX, No. 5 385

3286 H. FOSTER BAIN

the work of clearing off timber, chose prairie land. It thus hap-
pened that from early boyhood Samuel Calvin was familiar with
the great granite bowlders that mark the fertile prairies covered
by the Iowan drift. Between farm work, school, and the usual
country sports, his time was fully occupied until about 1861, when
he entered Lenox College, at Hopkinton, near by. Lenox College,
was, and is, an excellent example of the small denominational
colleges that the pioneers of the Middle West founded so prolifi-
cally and supported with so much sacrifice. Without the equip-
ment of a present-day university, or a staff of world-famous pro-
fessors, it was still an excellent place for a young man desirous of
getting at the fundamentals of the simple college curriculum of a
half-century ago. Here Calvin remained and studied until near the
close of the great Civil War, when, in company with most of the
instructors and students who had not already gone to the front, he
enlisted in 1864 in one of the Iowa regiments. Fortunately the
war was nearly over. His military service was therefore neither
long nor was it distinguished, in the sense of taking him into great
battles. For the most part it was a period of dull routine, of guard
duty and of marching, of occasional small skirmishes with the
enemy, and a continual private skirmish for acceptable food and
some comfort. He learned the rudiments of a soldier’s life and the
routine of camping—the latter much the more valuable to him.

At the close of the war, Calvin, with many others no longer
young, went back to college to finish his studies. The college,
however, had been practically wrecked. The call for men had
taken both instructors and students, and while the buildings were
still there, the life of the institution had been nearly broken up.
After the ensuing reorganization Calvin found himself in the ranks
of the instructors rather than among the students, and the inter-
rupted college course was only completed as a result of much hard
private study.

At Lenox College, among other members of the new faculty,
was Thomas H. Macbride, a graduate of Monmouth College, and
a man who had had the advantage, then unusual for teachers in
small western colleges, of study at the University of Bonn. Mac-
bride’s interests centered in botany, and Calvin, while broadly

SAMUEL CALVIN 387

concerned with the whole of natural history, was already beginning
_ to specialize in paleontology and geology. The two men became
intimate friends and close companions. ‘Together they explored the
neighborhood and later, in the long vacations, the more distant
parts of Iowa. With team, covered wagon, and simple camp outfit,
trips were made as far west as the Missouri River, and collections
of various sorts were brought back to enrich museum and class-
room instruction. In the course of this work Calvin came into
contact with C. A. White, at first state geologist and later professor
in the State University at Iowa City. When White went East
Calvin succeeded him at the university, and when the Iowa Geo-
logical Survey was re-established in 1892, he also followed him in the
position of state geologist. The change to Iowa City, which took
place in 1874, was an agreeable one, since the university, having
larger resources, offered a larger opportunity for work; and for
work Calvin always was greedy. The State University of Iowa
in 1874 was not a large institution and the professors found plenty
to do. Calvin occupied what has been aptly described as the
“settee rather than chair” of natural history, and, as he once
whimsically phrased it, he was ever after ‘“‘shedding professor-
ships.” As rapidly as funds would permit he divided the work
and called other men to him. Among the first was Macbride,
then Nutting, and others in succession until in the closing years
of his work it was not only possible for him to confine his work to
geology, but to have the aid of an able corps of assistants in that.
His work in the other sciences, however, was more than time-
serving. His interest in animal morphology was especially keen,
and in organizing and conducting zodlogical explorations he did
work of real value. The results of the Bahama expedition, which
brought back such unheard-of wealth of specimens of living crinoids,
were due in no small part to him.

As a geologist Calvin’s name and fame are principally bound up
with that of the lowa Geological Survey, which, except for a brief
interim, he directed from the day of its organization, in 1892, to the
day of his death. As a former member of the staff of this Survey
I may be over-partial, but it is none the less my conviction that,
considering time, place, and means, the Iowa Survey is and has

388 H. FOSTER BAIN

been one of the best-conducted institutions of its kind in America.
It serves the people and the state of Iowa well, meeting their
peculiar needs. In other states different methods are necessary,
as they will become in time in Iowa.

The Iowa Survey owes much to Calvin. It also owes a not-to-
be-forgotten debt to Charles R. Keyes, the principal assistant at
the time the Survey was organized and through the period when
plans were being formulated. Im brief the Survey has served
two main purposes: (1) It has furnished handbooks, consisting of
maps and reports on the geology of the individual counties, written
in simple language adapted to the understanding of students and
intelligent laymen; (2) scientific and technical reports have been
issued as occasion offered, covering all phases of the natural history
of the state and the economic development of its resources.
According to the report for the year ending December 31, 1909,
all but nine counties had been surveyed and reports prepared and
issued. More detailed surveys, based on topographic maps made
in co-operation with the United States Geological Survey, had
already been begun in areas of especial economic importance, and,
as conditions permit, this system of more refined mapping will
doubtless be extended over the state. In the meantime the county
reports serve extremely useful purposes and afford a sure basis
for broad general studies. The special reports on scientific and
economic subjects have been numerous and valuable, as is attested
by the list of publications of the Survey. The water, the coal,
clay, stone, lead, zinc, gypsum, and minor mineral resources have
all been studied by specialists, and information essential to their
economical development set forth. The mineral industry has
responded to the stimulus and the total value of the mineral output
of the state is now many times what it was when the Survey was
organized. Towa is primarily an agricultural state and its mineral
resources are relatively small; the educational phases of the Survey
work have therefore always, and properly, been emphasized. On
the narrow material basis, however, the Survey has made good
return for the support of the state and it is deservedly popular.
As an administrator, therefore, Calvin’s work shows him to have
been successful.

ee)

SAMUEL CALVIN 389

In scientific research, Calvin’s personal interest lay mainly in
paleontology and, in later years, in the study of the Pleistocene
deposits. Aside from contributions to the paleontology of the
Paleozoic invertebrates, Calvin will probably be best remembered
for the discovery of the fauna of fish remains in the Devonian beds
near Iowa City, and for his studies of the vertebrate remains of the
Aftonian deposits. The fish remains have been investigated by
C. R. Eastman, who found in them much of interest. The Afto-
nian bones are important because they permit fixing the age of a
widely scattered series of puzzling deposits. In his last published
administrative report! Calvin speaks of them as follows:

This remarkable interglacial fauna is not altogether new to science. The
individual species, and to some extent the fauna as a whole, have for some
time been known to students of paleontology. It has also been known that
some of the species were at one er more times inhabitants of Iowa. But, so
far as concerns Iowa, it was not known that the few discovered forms, which
heretofore have been represented by isolated finds, were contemporaneous;
and outside of Iowa, in territory ranging from Texas to western Nebraska,
the exact age of the beds in which the remains of this assemblage of extinct
mammals were found was not definitely fixed. The fauna as a whole is
markedly different from that familiar to the pioneer settlers of this State,
very different from that known to the pioneers in any part of America. True
horses were represented by at least two species, both quite distinct from our
domestic species; there were three species of elephant, one of imperial size,
and there were two mastodons, making in all five great proboscidians; there
was at least one species of camel, an extinct bison, a gigantic stag, and two
ponderous, awkward, clumsy ground sloths. The smallest of the three ele-
phants seems to be identical with the hairy elephant or northern mammoth
of Europe and Asia; it furnishes to this unique fauna a distinctly boreal
element. The two great sloths, on the other hand, contribute an element
distinctly South American. As found in Iowa, the age of the fauna is definite
and clear. The beds in which the remains occur belong to the Aftonian stage;
these animals lived, and the beds in which their remains were buried were
laid down, in an interval of comparatively mild climate between the first
and second stages of Pleistocene glaciation.

The quotation illustrates at once Calvin’s broad scientific
interest and the singular clearness of his writings, which makes it
a pleasure to readers and a fit model for beginners.

Calvin’s active interest in the Pleistocene deposits dates from

t Towa Geol. Surv., XX, xxii.

390 H. FOSTER BAIN

1896. In the spring of that year he undertook to put into shape
long-accumulated notes on Johnson, the county in which Iowa
City is situated. It chances that two lobes of Iowan drift reach
across the northern border of this county. South of these lobes
are the loess hills characteristic of much of the Iowan border and,
in turn, the broad loess-Kansan plains. At that time the southern
boundary of the Iowan had not been traced. From the known
presence of two drifts at Afton and elsewhere in southern Iowa,
it had been inferred that the Iowan boundary was much farther
south than now appears true. The battle for two ice-sheets has
been but too recently won to encourage belief in many. Calvin,
however, intimately familiar with the typical Iowan drift plane of:
Buchanan and Delaware counties, recognized at once that the phe-
nomena of southern Johnson County required a new interpretation,
and shortly thereafter hit upon the clue. The rest of the staff,
inspired by his enthusiasm, started out like crusaders to over-
turn and rebuild the Pleistocene column. The field was particu-
larly favorable since in Iowa the different drift sheets are mainly
deployed rather than superimposed, and since, also, nearly the
whole sequence is represented. With the kindly counsel of T. C.
Chamberlin, with friendly visits from R. D. Salisbury, J. E. Todd,
Albrecht Penck, Frank Leverett, and others, the work went
rapidly. There were many field conferences, and the winter meet-
ings of the Iowa Academy of Science became notable for the dis-
cussion of current Pleistocene problems. Naturally there were
differences of opinion and later work has shown the need of some
revision of first-stated conclusions. Out of it all, however, has
come the recognition of the independence of the pre-Kansan, the
thorough establishment of the Aftonian, and the concept of the
Iowan ice sheet. As to the latter, especially, there has been, and
still is, much difference of opinion. The Iowan drift is so peculiar, it
is so local, and the phenomena are so puzzling, that some find them-
selves unable to accept the evidence of its existence. It is not
my purpose to review the proofs. That has already been done
most excellently by Calvin himself. It is sufficient to repeat here
a remark made by him at the close of the first field season devoted
to this study: ‘‘The Iowan ice sheet did so many queer things that

SAMUEL CALVIN 301

we will never blame anyone not familiar with it in the field for
denying its existence; but, whatever the explanation, there is a con-
sistent and co-ordinate set of phenomena that demands explanation,
and that is best interpreted by the hypothesis of a separate Iowan
icersheet.

Aside from his work at the university and on the Iowa Survey
Calvin did his full share in the general work of his chosen profes-
sion. While he was not especially interested in economic geology,
his advice was sought and valued by a number of Western mining
companies; he was a member of the first Conservation Conference
at the White House; he served on the National Advisory Board
on Fuels and Structural Materials; he was an active member and
officer of numerous professional societies, including the Geological
Society of America, of which he was president in 1908; he was
one of the founders of the American Geologist, and of the Associa-
tion of State Geologists; and in many other positions he made his
influence felt. He was a charming writer, a popular lecturer, and
a most inspiring teacher. His personal influence was strong and
deep, and the thousands of students who came into contact with
him are today better men and women because he lived. He left
a stainless record as a man and citizen, and an inspiring example
to young men of the profession.

THE EVOLUTION OF LIMESTONE AND DOLOMITE.
II (Concluded)

EDWARD STEIDTMANN
University of Wisconsin

PART If. CALCIUM AND MAGNESIUM IN THE PRODUCTS OF
METAMORPHISM

The products of metamorphism of the rocks may be classed
as solids and solutes, or residuals and losses. Residuals, the mate-
rials which remain in situ after a rock has suffered chemical change;
losses, the materials which are dissolved, transported in solution,
and redeposited elsewhere. A study of the fate of calcium and
magnesium in rocks subjected to metamorphism shows that there
is nearly always a marked tendency for a greater percentage loss
of calcium than of magnesium. Magnesium tends to remain
with the residuals to a greater degree than calcium. It will be
shown that in the movement and redisposition of the residuals
and losses of rock alteration, and in the reworking of these products
by the same processes, again and again throughout geologic time,
lies the history of a progressive enrichment of the lands in calcium ,
and their progressive depletion in magnesium. The evidence for
the selective splitting off of calcium from the parent rocks in
response to metamorphic processes and the accumulation of
magnesium in the residuals follows.

Materials lost by the weathering of acid igneous rocks.—The
weathering" of acid igneous rocks results in the loss of lime, mag-
nesia, soda, potassa, and silica. The percentage loss of the various
constituents approximately follows the descending order in which
they are named. For purposes of comparison alumina may
be regarded as constant. The ratio of calcium to magnesium lost
in the weathering of an acid igneous rock can only be given in
terms of tendencies. In Table V the figures for the ratio of cal-

t Edward Steidtmann, ‘‘A Graphic Comparison of the Alteration of Rocks by
Weathering with Their Alteration by Hot Solutions,”’ Economic Geology, III, 381-409.

392

EVOLUTION OF LIMESTONE AND DOLOMITE 393

cium to magnesium lost are based on the assumption that alumina
has remained constant. The percentage loss of calcium averages
higher than that of magnesium, a tendency generally character-
istic of metamorphic processes.

TABLE V
WEATHERING OF AciID IGNEOUS ROCKS

Ca/Mg Ca/Mg PERCENTAGE Loss
Rock FRESH IY ND) BONG S| | eral | SOURCE
Rock Lost Ca Mg
meGramites: 6. sa. 2.8 Bisse 5 at 31 Watson, Granites of Geor-
gia, 318
Pw Granitessesy ee. 4.9 7.6 98 64 Tbid., 315
BeGranites.. we Bas ae 88 Al Ibid., 321
Am GLaAMiterne er 6.9 5 59 82 Ibid., 320
Granites ila 3.4 4.6 43 32 Ibid., 309
GuGranites: 2.4: 5 238 2 50 Ibid., 312
7Granitesw on. 5 oO) 84 83 Ibid., 312
8 Granite ...... 3.8 3 74 06 Ibid., 327
OmGramitenss oa. 3.9 Ae 78 70 Ibid., 327
ToOMGranites. .. 1 Deal: 2.58 77 65 Ibid., 325
Tr Granitessiiis: a3 4.8 80 54 Average Georgia
nam Granitessc....c. a3 no mag- | 2 fo) Merrill, Rocks and Rock
nesium Weathering (Dist. of
lost Columbia), 207
Tom GramMitere ace: 13 no mag- | 21 fe) Ibid.
nesium
lost
14 Phonolite..... BER 12 17 5 Ibid. (Bohemia), 108
15 Andesite...... B ol 9.5 77 28 Ibid. (Grenada), 208
TOL OVeNMtes cs. -0.: 16500) Te 67 78 Clarke, U.S.G.S. Bull. 330,
412
E77 GMEISSs s/o, 4.2 Se LOO 76 Ibid.
IAVETAC CH ea 3.45 +4.12 59-7 50

Materials lost by the weathering of basic igneous rocks—In the
weathering of basic igneous rocks, the percentage losses of cal-
clum and magnesium average about even, in Table VI. The
ratio of calclum to magnesium lost varies between wide margins,
from one to infinity. The materials selected for analyses may
have unequaled value in the problem.

Materials lost by the weathering of an average igneous rock.—The
ratio of calcium to magnesium in an average igneous rock (Clarke)
is about 1.37. The ratio of calcium to magnesium lost by its
weathering, calculated on the basis of average calcium and mag-
nesium decrements, is about 1.85.

394 EDWARD STEIDTMANN
TABLE VI
WEATHERING OF Basic IGNEous Rocks
Ca/Mg Ca/Mg PERCENTAGE Loss
Rock FRESH MATERIALS SOURCE
Rock Lost Ca Mg
Te Diabasesn cic BaD 4.1 25 9.5 | Merrill, Rocks and Rock
Weathering (Medford,
Mass.), 218
2. Dialbasea meee ie) TS 83 61 Ibid. (Spanish Guiana),
222
BeiBasaltzeee sae 1.0 a iit 47 96 Ibid. (Crouzet, France),
223
A BAGEMWS s Ss oe oe 1.2 TA! 84 7h Ibid. (Kammer Bull.), 222
Si Wiabaseere sme 6 6 98.7 98.2 | Merrill, Am. Geol., XXII,
93
6) Diabases... 2) 04 6 98.6 | 98 Ibid., 95
iy ADSKOIAMESS oo uae 1.84 1.85 07-3 | 97.17| Merrill, Rocks and Rock
Weathering, 225
8 Augite diorite. TO, Baws 59 76 Morozewicz, Zeit. Kryst.
Min., CXXXIX, 612
9g Diabase..... : 1.08 BW) 84 42 P. Holland and Dickin-
son, Proc. Liverpool
Geol. Soc., VII, 108

ToMBOulder mak to | infinity W7/s || | CS) Helen Mine, Michipicoten
(unpub. monograph)

Tr Gabbronse es 2.92 Tey 8.9 6 Gabbro, Allen Junction,
Minn. (unpub. mono-
graph)

12 Diabase..... 2 AG Tats 92 82 Dike, Penokee-Gogebic
(unpub. monograph)

(AVCE AS Crete tere: Te 27 1.62 GOe3\ 2 Oms5, ie
TABLE VII
WEATHERING OF LIMESTONE
Ca/M. Ca/M,
Rock Frock Rack Meee Rack Source
Carboniferous lime-
SOME ewer eee 148 14.9 Ann. Geol. Rept. Arkansas (1890),
179
Average of three an-
DLV SESH een ee ene I.4 2 Bull. 7, Va. Geol. Surv., 97
Kn OK eae es eee 1.6 Or Russell, Bull. 52, U.S.G.S., 25
Galena, vee axe aoe TS Tey Bull. 14, Wis. Geol. Surv., 15-16
Galena. seen eeery TS 66 Ibid.
Galenaye ia eerie 5 64 Ibid.
aArashrances eae U9 2.38 Hilterman, Die Verwitierungs-
Produkte von Gesteinen der
Trias Formation, Frankens.
Inaugural Dissertation, Er-
langen, 1889

Plattentkallkcete esi 66.0 1.82 F. W. Pfaff, “‘Ueber Dolomit und
seine Erstellung,’’ Newes Jahrb.,
XXIII, 538

Krebscheeren Kalk.. . 61.0 THOT Ibid., 539

IAWeLa Seam aia 20.5 2.61

EVOLUTION OF LIMESTONE AND DOLOMITE 395

Materials lost by the weathering of limestones.—In the present
stage of earth evolution, the principal contribution of calcium
and magnesium from the weathering of the sediments probably
comes from limestones. A compilation of the calcium magnesium
ratio of several fresh and weathered limestones seems to indicate
that the percentage loss of calcium is somewhat higher than that
of magnesium and that the amount of calcium given off by the
weathering of limestone greatly exceeds magnesium (Table VII).

Résumé of weathering.—It follows from the facts stated that
the weathering of igneous rocks and sediments results in the loss
of more calcium than magnesium and that in general the percent-
age loss of calcium is greater than that of magnesium.

Materials lost by dynamic. metamorphism.—The dynamic meta-
morphism of sediments as well as igneous rocks seems to bring
about certain definite chemical changes. It is difficult, however,
to measure these changes since it is uncertain whether any of the
elements are stable in any given case. All that can be done in
the problem of determining the relative stability of lime and mag-
nesium under dynamic condition is to compare the magnesium
and calcium ratios in the unaltered materials with the calcium
magnesium ratios in their metamorphosed equivalents, as shown
by Table IX. Secondly, to compare the importance of calcium
and magnesium in the minerals of the unaltered and metamor-
phosed rocks. Table IX appears to indicate that the ratios of
calcium to magnesium are lower in the metamorphosed phases
than in the unaltered; that is, the percentage of lime lost by
dynamic metamorphism appears to be higher than that of mag-
nesium. Concordant with this apparent chemical change is the
fact that the minerals which are developed under conditions of
dynamic metamorphism are predominantly magnesium and
potassium bearing, rather than calcium bearing, such as the micas,
chlorites, and amphiboles of Table VIII. It appears that mag-
nesium is better adapted to dynamic condition than calcium.
A selective removal of calcium from the zone of anamorphism to
the zone of katamorphism and ultimately to the ocean seems to
be a logical sequence.

396

EDWARD STEIDTMANN

TABLE VIII

Tur PERCENTAGES OF CALCIUM AND MAGNESIUM IN CALCIUM- AND MAGNESIUM-
BEARING MINERALS, CHARACTERISTIC OF DyNAmMIC METAMORPHISM

Mineral Ca Mg
ANGLINOLItES favs scat ee nee 0.5 Teo Variable
Anthophyllites ere aie eee 0.20 28.69 Variable
VN ea oo vemai ae etal vanl element cious Area II.4 8.6 Variable
BIO ELE enc yeene area e recut eau eC [EN Uae etree Sara 14.3 Variable
Gh Ori tee Pei Us ere eae eyes 20.0 Variable
Gordieritems ) ecu os oe eeu reeegert: 6.1
EHonnblende te crrrs ete rere 8.7 8.64
Serpentine ss ec Sunpeerycece nl. aden ale 25.8
Spleen eee ec, aee ckcueeeraene aera yom olen TT. 15
Scapoliteevene ce secs cotusmuacien: Qe nim es [enn lay eel
sroummallane= Wee eae eteet et eee Teed! 8.9 Variable
Tremolite see ccs a ee On 4 14.9 Variable
Vesuviamites santa sre m-mec sed Dek 1.57 Variable
Wollastonite as meee see SAC Ok als denis, deniers
ZiOISICS oye telah oe cena etn ee 71 lint [yan an ee ic alee
TABLE IX
DyNnAMIC METAMORPHISM
Ca/Mg Ca/Mg
Rock Original Altered
Rock Rock Ih.
Average of 12 clays
angisoilsecne ace 15 Ae Clarke, Bull. 168, U.S.G.S., 1900, p. 296
Average of 78 shales... er aL Clarke, Bull. 330, U.S.G.S., 1908, p. 27
Average of 9 slates of
Vermontyas cena .25 | Van Hise, Mon. 47, U.S.G.S., 1904, p.
895
Dolomite nines see ite HOR Mon. 46, U.S.G.S. Altered to talc schist,
PDe2tG= 222
BURIED c Gon ob Ts5 .66
Gab bromusey: eon 95 .44 | Bull. 62, U.S.G.S., p. 76
Gab bromerw ie eicr eine 95 TO) 1i|) Bull 62) UES:G:S:. Up. 470.0 sAltered!
more than preceding case
GreenStoner ieee ie, 180) 1.05 | Bull. 62, U.S.G.S., p. 91
Gabbro diorite...... 1.45 .89 | Bull. 62, U.S:G.S., p. 80
MORE; occ do Tyee .62

Materials lost by contact metamorphism.—Contact metamor-
phism of the sediments tends to develop minerals of complex
constitution and high specific gravity. The materials in excess
of the requirements for the development of adapted minerals

tend to be removed, and in part may reach the sea.

The relative

EVOLUTION OF LIMESTONE AND DOLOMITE 307

instability of calcium at contacts as compared with magnesium
is suggested by the tendency toward increase in the magnesium
content of altered sediments, as compared with their unaltered
equivalents. cee, Lables XC XI, XIN The averages of the
tables are misleading since they do not represent the tendency of
the majority of cases.

TABLE X
Contact METAMORPHISM OF SLATES BY AcrID INTRUSIVES
- Ca/Mg Ca/Mg
Rock Fresh Altered
Rock Rock
Chloritic phyllite... . Our? ©), 22 Altered by granite (Neues Jahrb., 1897,
p. 156)
Slatempiscins sire oe 0.18 0.05 Altered by hornblende granite 50’ from
contact (Hawes, Am. Jour. Sc., Mt.
Willard, N.H.)
Slaten aaa ete: 0.18 0.14 | Ditto, 15’ from the contact
SlateAe eons es ees 0.18 By Ditto, 1’ from the contact
SIAtesr cs see cme °.18 pit Ditto, at contact
WaguiiGulchy 39.4... 0.39 0.87 Contact with quartz diorite (Bull. r50,
U.S.G.S.)
Morenci shales...... 0.82 0.55 Contact with porphyry (Bull. 229,
U.S.G.S., p. 348)
Composite. 342... 0.62 0.38 | Of 6 slates by acid intrusives
AMVEINGS 5 wig dos oo - 0.33 O93 7,
TABLE XI
Contact METAMORPHISM OF SLATES BY BAsic INTRUSIVES
Ca/Mg Ca/Mg
Rock Fresh Altered
Rock Rock
Composites. 225)... 88 .36 | 8 adinoles altered by diabase (Roth,
; Geol., III)
Icenmeschiefer:....... 49 .56 | Composite of 3 slates altered by dia-
base (ibid.)
Wenneschictersm. a. 55 .30 | Ibid., 147
Slattesip geet erence 09 .47 | Composite of 3 slates altered by dolerite
(Crystal Falls, Mon. 36, U.S.G.S.)
Slatesm tem e neers 19 .32 | Clausthal altered by diabase dikes
(Groddeck, Jahrb. der kéniglich-
preuss. Landesanstalt, 1855, pp. 1-53)
Witgestioviey 5 4°55 ab soso oe 04 .34 | By gabbro intrusive (Mon. 43, U.S.G.S.,
170)
Carboniferous....... Rou IO. Shale by peridotite dike (Bull. 348,
OeSHGES=9 5343)
Averare arene 1.04 Te 5

3098 EDWARD STEIDTMANN

TABLE XII
LimESTONE Contact METAMORPHISM
Ca/Mg Ca/Mg
Rock . Fresh Altered
Rock Rock
HMomestake:. 0... 27 I.O1 By andesite (Leith and Harder, ‘‘ Utah:
The Iron Ores of the Iron Springs,”
Dist. Bull. 338, U.S.G.S.)
Wihite: Kmnobsn.. eee 18.4 74.0 By acid intrusive (Kemp, Ueto Eco.
Geol., II, 1907)
IMIOrENCi aan nea: Bates) || to} Altered by porphyry (Eco. Gale IDLO,
1907)
Bimehamtee ae Gee 54 34 Altered by porphyry (Prof. Paper 28,
U.S.G.S.)
IBN. Goa a obec 13.2 39 Altered by porphyry (zbid.)
Chanarchilloy: 25: 25 57 Chile, altered by greenstone (Woesta,
Ueber das Vorkommen der Chlor. Jod.
Brom. Verbindungen in der Natur,
Marburg, 1870)
Slightly altered lime-
SLONGm nie re 7.4 D8 F. D. Adams, Jour. Geol., XVII (1909)
Slightly altered lime-
Stone: eae ce bhai TIS Ibid.

Materials lost from rocks by hot solutions.—The alteration of
rocks by hot solutions along fissures also shows a marked tendency
toward rapid removal of lime, and a much slower rate for the
removal of magnesium. In some cases calcite, epidote, and other
lime-bearing minerals develop in basic igneous rocks, but often
calcium is practically absent from the secondary minerals. The
compilation on page 399 has been made showing the calcium and
magnesium ratio of fresh and altered rocks adjacent to ore-bearing
fissures.

Résumé of calcium and magnesium in the products of metamor-
phism.—The data on metamorphism which have been presented
indicate that the percentage loss of calcium which rocks sustain
through metamorphic processes tends to be higher than that of
magnesium. In fact, it could be shown that the percentage of
calcium lost tends to be higher than that of any other element.
Exceptions are noted, of course. In view of this tendency, Salis-
bury’s' estimate that the disintegration of 55,000,000 cubic miles
of average igneous rock would yield the common salt of the sea,
while the disruption of three or more times as much rock would
be required to yield the limestones, is suggestive.

tR. D. Salisbury, ‘‘The Mineral Matter of the Sea,” Jour. Geol., XIII, 476-77.

EVOLUTION OF LIMESTONE AND DOLOMITE

399

TABLE XIII

Tue Catcium MAGNESIUM RATIO OF FRESH ROCKS AND THEIR EQUIVALENTS ALTERED
BY Hor SoLtutTions ADJACENT TO ORE-BEARING FISSURES

Ca/Mg Ca/Mg

Rock Fresh Altered

Rock Rock

Gramitezrns ses soto 1.00 18
Amphibole schist... . TeI5O TS,

Granites rseie.s ne 1.50 67.

Rhonolites ss. sees. 5-40 2.4
Granodiorite........ 1.04 5.0
Amphibole schist... . 34 Tee
Ibimestonen 5. en 4s LO) 1p

AMG 5 on 0066 oo ae 1.64 585

.67

.28

a 00

Monzonite porphyry ar 17
2

09
ae Goat
Monzonite porphyry Te) Bs2

Diorteres anes ae anor 1.4 1.03

Hornblende andesite . 2.50 oh. Ge

Hornblende dacite. . . 2.67 —2.86

Butte granite........ 1.95 .62

Butteyoramites. =... 1.95 53

Butte! granite... .. 1.95 SoG)

West Australia, Pilbara, Goldfield.
Quoted by Lindgren, Eco. Geol., I, 540

Kalgoorlie, West Australia. Quoted
by Lindgren, zb7d., 530-44

Lindgren and Ransome, ‘Cripple
Creeki ay Cole Ph 7raUESiGasentod.

Ditto

Lindgren, “‘Placer Co. Cal.,” A.I.M.E.
(1901), 586-87

| Ditto

Limestone altered by hot springs.
Spurry) Aspen, Colo. Mons 3i,
WESLGES 2 TO

J. E. Spurr, “No. 2 Tonopah,” Nev.

PAP 42 seo

. E. Spurr, ‘‘No. 3 Tonopah,” zbzd.

. E. Spurr, ‘No. 4 Tonopah,” ibid.

. E. Spurr, ‘‘No. 5 Tonopah,” zbzd.

. E. Spurr, ‘‘No. 6 Tonopah,” bid.

. E. Spurr, ‘No. 7 Tonopah,” zdid.

. E. Spurr, ‘‘No. 8 Tonopah,” zbzd.

Lindgren, ‘‘Clifton-Morenci,” P.P. 43,
pp. 168-69

Ditto, No. 3

Ditto, No. 4

Ditto, No. 5

Boutwell, ‘Bingham District,” P.P.
38, p- 178

“Willow Creek District, Idaho,” 20
Anne Rept. U-S.G:s., bt. Ui 21132

“No. 3, Hauraki Gold Fields,” Eco.
Geol., IV (1909), 637

“No. 2, Hauraki Gold Fields,” zbid., 638

“No. 2, Sericitized Granite,’ unpub-
lished investigation, University of
Wisconsin

| “No. 8, Granite Mineralized,’ unpub-

lished investigation, University of
Wisconsin

“No. 9, Hard Silicified Granite,’’ unpub-
lished investigation, University of

Wisconsin

It is obvious that if metamorphism continued until all rocks
were separated into end products, the residuals remaining in
place and the materials lost transported to the sea, it would result
in a running down of the calcium content of the lands, and a
relative increase in magnesium.

400 EDWARD STEIDTMANN

In the deep zones of high pressure and temperature, where
there is only slight mobility of the residual materials, this result
may be reached and perpetuated for a long time until, in the
course of geologic ages, they finally become the shallow zones of
low temperature and pressure. Here the residuals of metamor-
phic processes as well as the materials lost are forever in a state of
motion in response to the movements of the atmosphere and the
hydrosphere, controlled by gravity and the sun. Thus the prod-
ucts of metamorphism are redistributed into the sedimentary
rocks, and these in turn are reworked and redistributed. In this
redistribution lies the potentiality of an increase of the ratio of
calcium to magnesium of the lands with geologic time.

Has sedimentation increased the ratio of calcium to magnesium
of the lands during geologic time?

The sedimentary rocks are derived from other sediments and
from igneous rocks, ultimately they are derived from igneous
rocks. Clarke’s average igneous rock is generally accepted’ as
representing the approximate composition of the primitive litho-
sphere. The criticism may be offered that this average is neces-
sarily not based on a study of the volumetric importance of the
various igneous rock types in the primitive lithosphere. It has
also been maintained that the igneous rocks themselves are very
largely derived from the fusion of sediments, which may be so
but has not been proven. The recurrence of certain predominant
igneous rock types at various times and places suggests that the
composition of magmas has not been materially influenced in the
way which one would expect from regional subfusion of sedi-
ments. It seems probable that the primitive lithosphere had a
composition between rhyolite and basalt, which is expressed in
Clarke’s average. Approximations, not finalities, seem all that
can be hoped for in this problem.

By an ingenious graphic method, W. J. Mead' estimates that
the average igneous rock is equivalent to shales, sandstones, and
limestones of Clarke’s average compositions in the ratio of 80: 11:9.

F. W. Clarke? has made a similar estimate, based on average

1 W. J. Mead, ‘‘ Redistribution of the Elements in the Formation of Sedimentary
Rocks,” Jour. Geol., XV (1906), 238.
2 FW. Clarke, “‘Data of Geochemistry,” Bull. 330, U.S.G.S. (1908).

EVOLUTION OF LIMESTONE AND DOLOMITE 401

chemical compositions, in which he distributes the average igneous
rocks into shales, sandstones, and limestones in the ratio of 80:15: 5.

An earlier estimate by Van Hise’ divides the sedimentary rocks
into 65 per cent shales, 30 per cent sandstones, and 5 per cent
limestones.

A computation made by myself, using Mead’s method, shows
that a composite Georgia? granite made from Watson’s analyses
is nearly equivalent to a mixture of composite Georgia clay (Wat-
son’s) and average sandstone (Clarke’s) in the ratio of 55:45, not
enough lime and magnesia being present to be available for lime-
stone. Another computation by myself shows that a composite
basic rock made up from composites of diabase, gabbro, basalt,
and peridotite in the ratio of 6:6; 6:1 is equivalent to average
shale and limestone (Clarke’s) in the ratio of 88:12. The upshot
of ail these computations and estimates seems to be that the
predominant igneous rock types are equivalent to a large per-
centage of clastics, predominantly mud or shale, and a relatively
small percentage of limestone, hence the same would be true of
the primitive lithosphere, regardless of whether it was entirely
rhyolite or entirely basalt.

Under the theory of the stability of oceanic and continental
segments, the redistribution of the primitive lithosphere into
sediments may have taken place along one or the other of two
uniformitarian directions. The redistribution materials may
have been deposited upon the continents and in the oceans in
such proportions as to leave the composition of the lands unchanged.
This might be termed “‘integral”’ redistribution, because it leaves
the composition of the lands as a whole as it was before. Obviously
“integral”? redistribution of the redistribution materials to the
nth power would not change the composition of the lands. But
redistribution has certainly changed the composition of the lands
with respect to one element at least—sodium. That the lands
contain less sodium now than in the past, in consequence of leach-
ing and the accumulation of non-sodiferous sediments on the

tC. R. Van Hise, ‘‘Treatise on Metamorphism,” Mon. U.S.G.S., XLVII (1904),

940.
2 Watson, Bull. No. g-A, Geol. Survey of Georgia.

402 EDWARD STEIDTMANN

lands, is clearly shown by Becker’ in his recent contribution,
‘“‘The Age of the Earth.”

Instead of leaving the composition of the lands as before,
redistribution might result in a selective withdrawal of certain
elements from the lands and possibly the retention of others.
This may be termed “‘selective”’ redistribution. Redistribution
has been selective with respect to sodium, resulting in a progressive
decline in the contribution of sodium from the lands to the sea.
It probably has been selective with respect to potassium, causing
only a slight accumulation of potassium in the sea as compared
with sodium. The question is raised here whether selective redis-
tribution may not have caused an actual progressive increase
in the calcium content of the lands and a correlative progressive
decrease in magnesium, which in turn may have been ‘connected
with a similar progressive change in the ratio of calcium and mag-
nesium contributed to the sea, and of the calclum and magnesium
carbonates deposited in the sea. It has been pointed out that
regardless of whether the primary lithosphere was rhyolite or
basalt, redistribution would result in a large proportion of clas-
tics, predominantly mud, and a small proportion of limestone. If
redistribution has been integral with respect to clastics and lime-
stones, it would follow that the sediments exposed on the conti-
nents are predominantly clastics and subordinately limestones.
This test will be applied here to the continental interiors, the
continental margins, the epicontinental seas and the deep seas,
so far as the progress of my studies permits.

The geologic record of the continental interiors —The greater
portion of the surface of the lands consists of sediments. Major
Tillo? estimates that the Archaean and younger eruptives constitute
only 24.3 per cent of the known area of the continents. It follows
from obvious reasons that the greater part of the calcium and
magnesium now being delivered to the sea by the rivers comes
from the sediments exposed on the lands, and the proportions of
calcium and magnesium in the rivers will be roughly proportional

UGE Becker, “abhe Nee of the Earth,” Smithsonian Inst. Miscellaneous Collec-
tions, LVI (1910), No. 6.

2 Quoted from Berghaus’ Atlas der Geologie (1892).

EVOLUTION OF LIMESTONE AND DOLOMITE 403

to the amount of calcium and magnesium in the sediments and to
the relative solubility of calcium- and magnesium-bearing minerals
in the sediments.

In his discussion of ‘‘The Metamorphic Cycle,” C. K. Leith?
says:

Averages of sections made from field observations give uniformly a lower?
percentage of shales and higher of limestones. An average of twenty-one
sections from different parts of the United States shows thirty per cent of
limestone. If the difference of proportion determined by the chemicals and
field methods is a real one, as inspection of the data seems to indicate, the
significant questions are raised, (1) whether there may not be a concen-
tration of limestones on the continental areas, their complimentary shales
and muds being in the deep sea, (2) whether limestone may not be concen-
trated in the upper, observed part of the lithosphere, because of its known
inability to remain in the deep seated zones of high pressure and temperature.

That the Paleozoic sediments of the Mississippi Valley show
a surprising concentration of limestones amounting to from 23.6
to 66.6 per cent of the sections averaged and a marked deficiency
of shales and sandstones is brought out in an admirable study
made by Miss F. W. Carter.4 The results of this study are com-

piled in Table XIV.
TABLE XIV

TABLE SHOWING THE RELATIVE PROPORTIONS OF LIMESTONES, SHALES, AND SAND-
STONE IN THE PALEOZOIC OF THE MISSISSIPPI

State Limestone Shale Sandstone
Pennsylvania....... 23.6 47 25
Vall aiid ays eee iene Hae 52 23 Bias
Onion ae race, ele Bono 4l.4 23.6

SE Mnchicambenns eee MD 38.3 TOL
lmeianareccced) nese 30 30.3 30.6
WWisconsimgane eee a. 52 38.3 9.5
IM DIOUMNESONES Go teo on ae 50.9 40.4 TS
Moat tes cite, oh Ses Omer 2000 9.7
IVINSSO UTI ey are 66.6 22.8 10.4
@OKlahomayiys. 4.5. Bie BO}. 2) TO. 7,
Colorado—eastern. . . Di ats 4.8 57.6
Colorado—central.. .. er, 20.9. 21.9

~C. K. Leith, “The Metamorphic Cycle,” Jour. Geol., XV (1907), 304.

2 Lower than the percentage gotten by distributing an average igneous rock into
average sediments.

3 The chemical method of W. J. Mead (of. cit.).

4 Unpublished thesis (1910), University of Wisconsin.

404 EDWARD STEIDTMANN

The composition of the lmestones of the Paleozoic of the
Mississippi Valley averages that of magnesian limestones, with a
lime percentage higher than that of a normal dolomite.

The unconformities in the Paleozoic of the Mississippi Valley
represent the removal or lack of deposition of both limestones and
clastics, mostly clastics, as follows from the compilation below,
also made by Miss Carter (Table XV). Both sedimentation
and erosion seem to have worked hand in hand toward the con-
centration of limestones. ;

TABLE XV
TABLE OF UNCONFORMITIES IN THE PALEOZOIC OF THE MISSISSIPPI VALLEY

Kind of Rock Eroded

Location Extent Amount Eroded Summary
First base of St. | Widespread | Limestone Less than one-
Peter sandstone L. magnesian half thickness
Second base Ma- | Widespread | Galena lime- Negligible
quoketa shale stone Took of
Third top of Si- | Widespread | Salina and Ni-|} Slight EN oe
lurian agara lime- umiesroue
{=}
stone
Fourth top of | Widespread | Limestones and | Much
Mississippian shales
Fifth ever since | Widespread | Shale, sand- More than pre-| Took off more
Carboniferous stone, and ceding com- clastics than
some lime- bined limestones in
stone preceding

It seems to follow that the sediments of the Mississippi Valley
were either derived from sediments already high in limestones,
or else the complementary muds have been carried elsewhere, to
the margins of the continents perhaps. But even granted that
they were derived from sediments high in limestones, it is diffi-
cult to escape from the conclusion that ultimately redistribution
was selective. Concentration of limestones on the lands began
somewhere at some time. A selective withdrawal of muds from
the continents began.somehow, for the Paleozoic sediments of
the Mississippi Valley show a proportion of limestones far in excess
of the proportions gotten by redistributing either rhyolite or
basalt, the two dominant magmatic differentiates.

A remarkable preponderance of limestone is also evident from

EVOLUTION OF LIMESTONE AND DOLOMITE 405

the following averages made from sections in the interior of China,
described by Blackwelder in Researches in China.

; |
Section Shales Sandstone | Limestone | Unknown

see Per cent Per cent Per cent Per cent
Sinian system, Shantung, Northeastern
China (Cambro-ordovician, unconform-

tay AO TUlIIM CSEOIME) lysine ies ie le inieieos cues 14 nas 86
Shantung (Carboniferous) Hi eeu 20
Shantung, Permo-Mesozoic............ 36 40 ue 24
Shansi-Wu-Tai District. Average of Paleo-
zoic (unconformity on limestone)..... Clastics cae 80.5
19-5

Eastern Ssi Chuan and Lower Yang Tzi
Gorges. Paleozoic section (unconformity

on top of upper Carboniferous limestone) 17.6 6. 75.6

The continent of Europe shows a similar dominance of lime-
stones over clastics. In the southern province of sedimentation,
the record is nearly continuous from the Cambrian to the Pliocene,
and presents a proportion of limestones far in excess of the ratio
gotten by distributing an average igneous rock into the sediments.

Another peculiarity of the sediments on the continental interiors
is that they are generally less disturbed and less anamorphosed
than the sediments on the margins of the continents. The mar- -
ginal distribution of mountain ranges and volcanoes harmonizes
with this generalization. The fact that the sediments of the
continental interiors are generally less anamorphosed than those
of the margins is significant in regard to their chemical denudation.
Anamorphism tends to cause the decomposition of carbonates
and the development of complex silicates, but the silicates are
less easily dissolved, hence the relatively small amount of ana-
morphism of these sediments increases their importance as sources
of calcium and magnesium in river waters.

Taking the lime and magnesia contents of Clarke’s average
sediments merely as objects of illustration, the following table
suggests how important the concentration of limestone on the
continents may be in changing the ratio of calcium and magne-
sium in the river waters from what it would be if the lands had
the composition either of an average igneous rock, rhyolite or
basalt.

409 EDWARD STEIDTMANN

TABLE XVI

Percentage of Percentages of

Rock Percentage | Percentage Ratio Average Paleozoic Sediments
CaO MgO CaO:MgO Sediment of Missouri
: (Mead) (Carter)

Shales (Clarke).... Beye 2.44 Iyer 80 22.8
Sandstone (Clarke).| 5.50 1.16 reat TI 10.4
Limestone (Clarke) | 42.57 7.80 ip eyaial ) 66.6
Average igneous

rock (Clarke).... 4.79 2.30 Te Alcer
Rhyolite (Osann). . 1.43 38 Bear
Basalt (Osann).... 8.91 6.03 TAT

The ratio of lime to magnesia in the average sediment is about
the same as in the average igneous rock, 1.4:1. The ratio of
lime to magnesia in the Paleozoic sediments of Missouri would be
about 4:1 if their composition is like that of Clarke’s average
sediments. The numerical values are not positive, but they
point to the probability that the concentration of limestones on
the continental interiors may have had a surprising effect on the
lime and magnesia content of river waters, and ultimately on the
chemical deposits of the sea.

The record of continental margins.—Chamberlin’ has pointed
out that the sediments which fringe the margins of the continents
are characterized by a greater number of unconformities and
more intense metamorphism than the sediments of the continental
interiors. The imperfections of the marginal record therefore
make it impossible to make a fair comparison between the lime-
stone content of the marginal sedimentary column and that of
the continental interiors. It is perhaps significant that the mar-
ginal sediments of late Tertiary and more recent times are pre-
dominantly clastic, which suggests a synchronous relation between
continental expansion and the deposition of clastics.

Deposition within the too-fathom line during continental expan-
ston.—It is significant that in the present geologic epoch of con-
tinental expansion, the area of the epicontinental sea is limited
to about 10,000,000 square miles, perhaps less than a third of
what it has been during periods of great marine expansion. It is
also significant that the present period of continental expansion

«T. C. Chamberlin, Geology, III, 526.

EVOLUTION OF LIMESTONE AND DOLOMITE 407

is not favorable to limestone building in epicontinental seas.
The preponderance of clastics now forming on the shallows sur-
rounding the lands is such that the sediments within the troo-
fathom line are generally spoken of as consisting entirely of muds
and sands, although important limestone-building areas are found
around Florida, Yucatan, and on the Australian Great Barrier
reef. The dominance of clastics seems to be related to climatic
conditions and the rejuvenation of streams which has accom-
panied the rejuvenation of the lands. But shallow, epicontinental
seas in times past have been important areas of limestone deposi-
tion when their expanse was greater than now.

Deposition beyond the too-fathom line —The area of the ocean
is estimated by Murray as 143,259,300 square miles. The littoral
and shallow-water zones comprise about 10,062,500 square miles,
consequently the deep-sea area covers about 133,186,800 square
miles. The calcareous deep-sea deposits of terrigenous origin,
coral muds, and coral sands have an area of about 2,556,800
square miles or about 1.9 per cent of the deep-sea area. Of the
pelagic deep-sea calcareous deposits, the globigerina ooze com-
prises 49,520 square miles, pteropod ooze 400,000 square miles,
or a total of 49,920,000 square miles, 37 per cent of the deep-sea
area. The total area of deep-sea calcareous deposits thus constitutes
about 39 per cent of the deep-sea area.

The terrigenous non-calcareous muds have a total area of about
16,050,000 square miles, or about 11 per cent of the deep sea.
The pelagic non-calcareous deposits have an area of about 64,670,-
ooo square miles, approximately 48 per cent of the area of the deep
sea, of which red clay represents 51,500,000 square miles and
diatom 00ze 10,880,000 square miles. In total, the non-calcareous
deep-sea deposits cover about 59 per cent of the deep-sea area.

The content of calcium and magnesium in samples of deep-sea
deposits collected by the Challenger expedition has been compiled
in Table XVII.

It shows that calcium is more abundant than magnesium, the
ratio of calcium to magnesium being about 13:1. The report on
deep-sea deposits by the Challenger expedition concludes that the
average calcium carbonate content of the deep-sea bottom is about

408 EDWARD STEIDTMANN
TABLE XVII
i Mean Denth Ratio of Cal- Macnee ‘ Approximate Per-
Deposit athe! Maen Bereeneave eae centages ol (free of
Coraltsandian ers: 176 TQ).22 1.8 34.6 coral ss and
muds
1.40

Green sand........ 440 30: .64 20.0 )
Green mud........ 513 10.20 “59
Red smiuditer seer 623 43:1 04 TO}55 .07
Coralomudiasae AOE Tiers, Wee see B Area) Seale eee
Vocanic muds..... Loci eA Ie Ne pte Salo)
Volcanic sands..... 16:1 .99 TOMO pel ag
Pteropod ooze..... 1,044 76:1 42 RD .28
Bluetmuds.7: 3.4. 1,411 Apia 56 2.71 10.00
Diatom ooze...... 1,477 28:1 a2 9.17 7.60
Globigerina ooze .. 1,996 Ig: 1.38 26.3 34.50
Radiolarian ooze.. . 2,004 Nes 1.84 4.19 1.60
Rediclay a0 es si2: 3,730 Sa .70 3.48 36.00

92.66

37 per cent, of which fully 90 per cent is derived from the remains
of calcareous organisms living near the surface of the sea.
ever, the 37 per cent calcium carbonate at the sea bottom merely
represents the difference between solution and deposition.
tion of the calcareous remains according to the Challenger report
is a very important process, resulting principally from the genera-
tion of carbonic acid by the decay of the dead organisms.

It is to this fact that the decrease in calcium carbonate with

depth is supposed to be due.

TABLE XVIII

TABLE SHOWING RELATION OF CACO; TO DEPTH OF WATER, TAKEN FROM
CHALLENGER REPORT

14 cases under 500

(73

7
24
42
68 ce
65 ce

8 co

from 500 to 1,000

+ | T,0001tO1 500
1,500 tO 2,000
2,000 to 2,500
2,500 to 3,000
3,000 to 3,500
3,500 to 4,000

Over 4,000

fathoms
a9

Average Percentage

CaCO; 86.
CaCO, 66.
CaCO; 70.
CaCO, 69.55
CaCO, 46.73
CaCO; 17.
CaCO,
CaCO,
CaCO; trace

How-

Solu-

See Tables XVII and XVIII.

EVOLUTION OF LIMESTONE AND DOLOMITE 409

The calcium content of the ocean is a variable controlled by
its solution and deposition in the ocean and its introduction from
the lands. It is therefore barely possible that calcium is now
accumulating in the sea, partly from direct chemical reasons, the
calcium content of the ocean being below the saturation point,
and partly because the shallow-water area, most conducive to the
biochemical deposition of calcium carbonate, is relatively limited
during the present epoch of continental expansion; and partly
because the shallow waters bordering the continents are now con-
siderably polluted by mud and other land débris which depreciates
the shore zone as a habitat for lime-secreting organisms. Present
climatic conditions also restrict the life zones favorable to shallow-
water limestone deposition. Murray and Irvine’ have concluded
from experimental evidence that the calcium carbonate of the
sea is probably nearly constant in quantity, since the precipitating
agents of the sea probably maintain a balance between the intro-
duction and deposition of calcium carbonate, despite the fact
that the calcium carbonate content of the sea is below the satura-
tion point. Whether or not calcium carbonate is actually accumu-
lating in the sea seems uncertain, when the wide range of pre-
cipitating conditions controlled by the temperature, pressure, and
the relative abundance of living and decaying organisms is con-
sidered. Nor would annual analyses of sea water give any clue,
since it has been estimated that it would require about 680,000
years to accumulate the calcium carbonate now in the sea at the
present rate of contribution from the land, a fact which in itself
may be significant of the possibilities in this problem. Judging
from the selective solubility of calcium carbonate with respect to
depth, it seems that the widening of the epicontinental sea to
approximately 30,000,000 square miles during the Carboniferous,
as estimated by Chamberlin, must have given a tremendous
impetus to the deposition of calcium carbonates on these extensive
shallows. Here wave agitation might cause mechanical precipi-
tation, and would minimize the carbonic acid content of the waters
which might otherwise be influenced by organic decay. Evapora-
tion would tend to cause concentration. Thus in shallow waters,

t Proc. Roy. Soc. Edinburgh, XVII (1890). 81.

410 EDWARD STEIDTMANN

calcium carbonate may become so unstable through these and
other causes as to result in direct chemical precipitation as shown
by the well-known case described by Willis’ in the Everglades off
the Coast of Florida and that of Lyell? in the mouth of the Rhone.
In shallow, warm waters near the lands, the deposition of calcium
carbonate through lime-secreting organisms is very much more
rapid than in deep waters.

While 90 per cent of the accumulations of calcium carbonate
on the floor of the present deep sea come from the skeleta of free-
swimming organisms which thrived within the photobathic zone
in shallow waters, the remains of both the free-swimming and
benthos organisms augment the rate of accumulation. Further-
more, the chances for the preservation of skeleta are many times
better in shallow water than in the deeps, as shown by the decrease
in the calcium carbonate content of marine deposits with depth.
In sinking through miles of water, the remains of pelagic organisms
often dissolve before reaching the bottom. Not only is there a
very clear dependence of abundant limestone deposition on shallows
in the present seas, but from the physical evidence of ripple marks,
etc., Schuchert concludes that North American Paleozoic lme-
stones were probably all deposited in less than 300 feet of water.
The food supply is another very important factor which attracts
lime-secreting organisms to warm, clear, shallow seas near the
continents.

The activity of the lime-secreting organisms would be further
stimulated by the climatic moderation and uniformity which
seem to accompany periods of oceanic expansion. The warming
of the seas, consonant with oceanic expansion according to Cham-
berlin’s hypothesis, would diminish its capacity for carbonic acid
and decrease the solubility of calcium carbonate. But the shallow
epicontinental sea, it seems, would be most susceptible to solar
heating, hence from a combination of causes, mechanical, physical,
chemical, and organic, limestone building in the shallow seas would
probably be intensified in more than arithmetical ratio to the
increase in the area of shallow water. The total contribution of
calcium from the land would be lessened because of the decreased

1 Jour. Geol, Me 8og)ns ts 2 Principles of Geology (12 ed.), I, 426.

EVOLUTION OF LIMESTONE AND DOLOMITE All

area of the lands. Could not a depletion of the calcium carbonate
content of the sea result from intensified deposition on the sub-
merged continents? What then? The solubility of the calcium
carbonate toward the shallows from the deeps, a process now in
operation as shown by the results of the Challenger expedition,
would be accelerated. The selective accumulation of limestones
on the continents as shown by geologic sections would be con-
summated.

Significance of the deposition of muds in the ocean basins.—The
composition of river muds is variable, depending upon the com-
position of the lands over which the rivers flow. The longer the
delta region of a river, in general, the smaller probably will be
the amount of soluble materials in the muds. The Nile and
Mississippi muds may be regarded as typical of the larger streams
of the world. In an analysis of Mississippi mud'* the ratio of
lime to magnesia is 1.11:1 (Table XIX). The ratio of lime to
magnesia in an analysis of Nile? mud is 1.82:1.

TABLE XIX
TABLE SHOWING LIME AND MAGNESIA Ratios or NILE AND Mrssissitppr Mups

CaO MeO :
Percentage Percentage Ratio of CaO to MgO
INilesmud ee aes 4.85 2.64 82
Mississippi mud... .. 1.83 1.04 Sr

The analyses of Nile and Mississippi muds show a relatively
high content of magnesia, as compared with other sediments. It
follows that if any large proportion of muds is lost from the lands
through deposition in the ocean basins, it would mean a selective
abstraction of magnesia from the lands, considering the quanti-
tative importance of the muds. The ratio of suspended material
to total dissolved solids in the Mississippi at Memphis, according
to Dole’s yearly average, is 2.3:1. Mellard Reed has estimated
that the proportion of suspended to dissolved materials in the
river waters of the world is 66:33, or 2:1. Approximately one-
half of the dissolved material is calcium carbonate. The ratio

™ By C. H. Stone, Science, XXIII (1906), 634.
2 Analysis D., Bull. 330, U.S.G.S., 420.

412 EDWARD STEIDTMANN

of suspended materials or muds to calcium carbonate is about
4.4:1, which argues for a great deficiency in muds in the sedi-
ments now forming as compared with the proportion got by distribut-
ing average igneous rock under conditions most favorable to the
deposition of clastics, namely, the condition of continental expan-
sion. This is in line with the fact that the present lands represent
an accumulation of limestones. Of the muds now carried to the
sea, the major portion are deposited on the continental shelves, and
therefore have the potentiality of again becoming a part of the
land surface. J. W. Barrell* estimates that from 50 to 70 per
cent of the solids brought down to the sea by rivers is deposited
within the too-fathom line. But many of the large world streams,
the Amazon, the Congo, Indus, Ganges, and others, have their
terminations near the too-fathom line. Amazon muds have been
traced to a distance of 300 miles from the mouth. Barrell esti-
mates that from 20 to 50 per cent of the muds from the rivers are
deposited beyond the too-fathom line, and are thus permanently
withdrawn from the lands. ‘This estimate is entirely in harmony
with the deficiency of clastics in geologic sections, and with the
probable withdrawal of magnesium from the lands which is regis-
tered in the decreasing magnesium content of limestones in going
up the geologic time scale. But the loss of muds from the lands
may have been even greater in the past, since many large streams
in various latitudes have submerged channels which in some cases
extend to the edge of the 1too-fathom line. On the other hand,
the percentage loss of muds undoubtedly was relatively much less
during periods of widespread continental submergence. But
during such periods, the total mud transported was very much
less, owing to the smaller relief of the lands and their floral blanket
resulting from the moderate, equitable climatic conditions which
appear to have accompanied the expansion of the seas. During
such periods, muds were accumulating on the lands, until periods
of continental uplift, like the present, accelerate their transpor-
tation toward the continental margins and the deep sea.

Does the ratio of calcium to magnesium in the sea show a selective
loss of magnesium from the lands with geologic time?—The ratio
of calcium to magnesium in the river waters of the world, taking

tJ. W. Barrell, Jour. Geol., XIV, 346.

EVOLUTION OF LIMESTONE AND DOLOMITE 413

Clarke’s data, is approximately 6:1. In the ocean, the ratio of
calcium to magnesium is 0.35:1. The relative amount of calcium
abstracted from sea wateris evidently many times greater than
that of magnesium. At the present time, a large proportion of
the calcium is being deposited in the deep sea, and is thus either
temporarily or permanently withdrawn from the land. A very
large proportion of the calcium delivered to the sea has, however,
been returned to the lands in the form of limestone deposits; in
fact there seems to have been a relatively greater return of calcium
carbonate to the lands than of the complementary clastics.:

In view of the excess of limestone on the lands, it seems highly
probable that the high magnesium content of the ocean represents
a selective withdrawal of magnesium from the lands during geo-
logic time. This may be one factor which could have caused a
decline in the proportion of magnesium contributed to the sea,
in the same way as the sodium contribution has declined with
geologic time, because of its accumulation in the sea.

Résumé of results of sedimentation and their effect on the ratio
of calcium to magnesium of the lands.—1. The marine sediments
which are revealed to the geologist on the continental interiors
were deposited during periods of widespread continental sub-
mergence. It is a significant fact that the sediments on the
continental interiors probably represent several times as much
limestone as could be gotten by redistributing an average igneous
rock, or average rhyolite or basalt. The gain in limestone seems
to be due mainly to a loss of the complementary shales and select-
ive deposition of limestones on the continental interiors. The
sedimentary mantle covers about three-fourths of the known
area of the continents. The ratio of calcium to magnesium in
the average igneous rock is about 1.37 to 1 (Clarke). The lowest
ratio of calclum to magnesium in any group of limestones in Daly’s*
compilation is 2.93:1, and the maximum 56.32:1. The ratio
of calcium to magnesium in Clarke’s average limestone is about
5 to 1. The ratio of calcium to magnesium in the average shale
(Clarke) is about 1.48 to 1; that of the average sandstone (Clarke),
5.5 tor. The dominance of sedimentary over Archean and erup-
tive terranes and the high percentage of limestones over muds

TR, A. Daly, Bull. Geol. Soc. of America, XX, 153-70.

4t4 EDWARD STEIDTMANN

indicate a higher ratio of calcium to magnesium of the present
lands than in the primitive lithosphere.

2. The marginal sediments show a tendency toward more in-
tense anamorphism, a greater number of and more profound uncon-
formities than those of the interior, and a dominance of clastics in
those sediments which were deposited during continental expan-
sion. More intense anamorphism! of the border sediments involves
a selective retention of magnesium in them.

3. Marine sediments on the present continental shelves within
the 1too-fathom lineconsist predominantly of clastics, from 50
per cent to 70 per cent of the river-borne sediments being deposited
here. This seems to afford a fair perspective of the nature of
sedimentation during continental expansion.

4. Areally the calcareous deposits constitute a minority of the
deep-sea deposits. The rate of accumulation of the terrigenous
deep-sea muds is probably vastly greater than that of the cal-
-careous deposits. Furthermore, a considerable portion of the
calcareous deposits goes back into solution, and has therefore the
potentiality of returning to the lands. The permanent with-
drawal of terrigenous muds from the land areas unquestionably
exceeds that of calcareous deposits. This selective withdrawal
suggests one factor in the causation of the loss of muds from the
continental interiors. Since muds not only tend to absorb more
magnesium than calcium, but actually show a high magnesium
content when compared to other sediments, it is not improbable
that the permanent loss of muds from the continents also involves
a selective and permanent loss of magnesium.

5. The selective retention of land-derived magnesium in sea
water may have been an important factor in causing an increase
in the ratio of calctum to magnesium of the lands.

HAS THE RATIO OF CALCIUM TO MAGNESIUM IN THE RIVER
WATERS INCREASED WITH GEOLOGIC TIME?

The lands have been shown to represent a higher content of

limestone than could have been gotten from the redistribution

of the principal igneous rock types which are generally accepted

t [bid., 37, “‘ Dynamic Metamorphism.”

EVOLUTION OF LIMESTONE AND. DOLOMITE 415

as approximating the composition of the primitive lithosphere.
In tracing the evolution of the limestones and dolomites to chemi-
cal changes in the sea, it is found highly probable that the ratio
of calcium to magnesium in the streams is higher at the present
time than in the streams of the primitive lands. This will develop
from the following considerations.

The influence of the terranes on the calcium magnesium ratio of
underground water and streams.—Unfortunately the data on the
calclum magnesium ratio of streams and underground water
cannot be regarded as a satisfactory basis for correlation with
the calcium magnesium ratio of the terranes over which they flow.
The chances of error in water analysis and the variability of the
composition of streams make a single analysis or even a group of
analyses a questionable basis of correlation. The yearly average
stream compositions based on daily samples gotten by the United
States Geological Survey’ for the streams of the United States
east of the rooth meridian constitute a creditable exception.

Judging by the data available, it seems that underground
waters and streams have a higher ratio of calcium to magnesium
than the terranes through which they flow. This agrees with the
fact that the metamorphism of rocks results generally in a higher
percentage loss of calcium than of magnesium. From Orton’s’
figures, the average ratio of calcium to magnesium in the Niagara
limestone of Ohio is 1.72. The rock waters as reported by Orton
in the Niagara limestone have the following ratios of calcium to
magnesium:

LOCALITY Ca/Mg
Sidineven@hiOwsne Asie eee as Sp. se Gea ee 4.0
Cehimara@ iO Reh wa ep ere eer cine oe 1.92
Moumitaimelarkey ODIO Ween len fale ee Beans
Houmtaimebarky@OMiOn jase). nee ee 2052
leita @iitayateete We ne emer a ekalcriay weaeee 22s
lard bun Gaetan. cy. ucvsan dacs cetera erate 2150,

An average of 66 analyses of well waters from sandstones given
in Bull. 4, of the University of Illinois, yields a ratio of calcium

«R. B. Dole, ‘‘Water Supply,” Paper 236, U.S.G.S.
2 Edw. Orton, Nineteenth Ann. Rept. U.S.G.S., Part to.

416 EDWARD STEIDTMANN

to magnesium of about 2.6. Twenty-four analyses of well water
from dolomites gave an average calcium magnesium ratio of 2.3.

None of the crystalline terranes from which stream analyses
are reported can be regarded as equivalent in composition to an
average igneous rock, in which the ratio of calcium to magnesium
IS about: 1.37 tOnr.

The analyses are of unequal value. Only those of the Chippewa
and Wisconsin are based on yearly averages. The calcium ratio
of the others may be too high or too low. In the following table,
the ratio of calcium to magnesium varies from 2.03 to 4.91.

TABLE XX

TABLE SHOWING THE CAtctuM MacGNestum Ratio IN STREAMS FLOWING OVER
CRYSTALLINE ROCKS

River Mg Ca Source

Arkansas River, Canyon,

BGs Clarke, Bull. 330, U.S.G.S., 59
Pigeon |Re) Manne csa: I BA al Or deom
Ottawa R. Low water (a)...| ~ 3.50 | Daly, Bull. Geol. Soc. Am., XX,
159

Ottawa R. High Water (d).. I 3.82 . | Ibid.
Ottawa R. mean (a) and (0) I 3.69 | Lbid.
Ottawa R. -(St/Anne)..... I 4.91 Ibid.
From granite terrane, aver-

age Ovamalyses ao. ge. ie I 3.20 | J. Hanamann, “Bohemia,” Ar-

chiv. Natur-Landesforschung

Bohmen, IX, No. 4

From mica schist, av. 6 an-
BLY SESieee sens toca ah cee I 2.48 Tbid., X, No. 5

Wisconsin River........... I 2.03 | Average of one year. Dole,
W.S. Paper, U:S.G.S., 236

Average of one year. Dole,
W.S. Paper, U.S.G.S., 236

Chippewa River........... I

is)
~I
e)

The following calcium magnesium ratios of streams on shales
and dolomites are based on yearly averages of daily samples

reported by Dole.
TABLE XXI
Tue Catctum MAGNESstumM RATIO IN STREAMS FLOWING OVER DOLOMITE AND SHALES

River Sample Mg Ca
Fox River,
Elgin, Ill............| Niagara dolomite I 1.70 | Average of I year
Fox River, Niagara dolomite and
Ottawa espe Cincinnati shale I 1.87 | ce oe ethic

EVOLUTION OF LIMESTONE AND DOLOMITE

TABLE XXI—Continued

Al]

River Sample Mg

Kankakee,

Kamniakees yi tiatn. » Niagara dolomite I
Rock,

Rocktord, Ml sea: 32: Dolomite and shale I
Rock,

Sircrabbares 10M oar oleae it anes I
White,

Nepales Whovelss aoe a0 be “ Sele I
White,

Indianapolis, Ind... .. oy Sea pe I
Cedar,

Cedar Rapids, Ia..... Silence I
Hudson,

ei somspNe Vine cece = it cnet I
Wabash,

Logansport, Ind...... Se pet gts I
Wabash,

Vincennes, Ind....... “s Ue a I
Tllinois,

ean Sallesilll eee ces. ng is I
Illinois,

aoe), Wc osne oops He pany I
Illinois,

Kampsville, Ill... .. ie ie sh: I
Towa,

lower Cityaila. =. a. a Soe ees I
Maumee,

Moledon Owe ssi. a eae I
Little Vermilion,

Streator lee testa = iY er I
Little Wabash.

Garris; Ws ois oo 6 hele is see I
Miami,

DENN, Ons aacaneses is ites I
Cache,

Mounds, Dl. 2.2... ue ES aia I
Big Vermilion,

IDeinyallls. Jo was ooo ts Saat I
Big Muddy,

Murphysboro, Ill..... BY hs er I
Embarass,

Charleston, Ill........ ss Semen I
Embarass,

Lawrenceville, Ill..... ES Sas I
Grand,

Grand Rapids, Mich. . : apie I
Muskingum,

Zanesville, O......... 2 De aS I
Sangamon,

IDyeernnwte, INN ois ds lo 8 bes y eaten I
Sangamon,

Spungiields lees: i. iY (oh ie I
Sangamon,

Chandlerville, Ill..... Sofa I

Average of I year

“cc co be (73

(73 co Ce 73
(73 cc 66 6c
(75 coe (a9
73 co 66 73
6c co Oe (73
(73 coe (a3
a3 (cana) cc
cc co ee (a3
(73 coe (a3
(73 cc 66 73
cc coe ce
(75 cc 66 (73
(75 cc 66 a3
“ce co 66 (73
(73 co ae “
(73 (7nd (a3
cc cc 66 (73
(73 cc 66 cc
(73 cc Ge “ce
(73 (7a ce
ce cc be ce
73 G15 oc
(73 ce 6 ce
(73 cee cc
(a3 ce 6 ce

418 EDWARD STEIDTMANN

The average calcium to magnesium ratio of these streams is
between 2.5 and three. The ratio of calcium to magnesium of a
normal dolomite is 1.61; that of an average shale 1.47 (Clarke).
The calcium to magnesium ratio of the streams is probably higher
than that of the terranes through which they flow.

An average of five water analyses on phyllite reported by
Hanamann shows a ratio of calcium to magnesium equal to 2.37.

The stream waters from limestone areas show a high calcium
ratio. See Table XXII.

TABLE XXII
TABLE SHOWING THE CALCIUM MAGNESIUM RATIO IN STREAMS FLOWING OVER

LIMESTONE
River Mg Ca Source
(Rhamesena cee reer I Tr s6): |) Bulls 330) 0, SiGiSe 75
Meuse, Liége, Belgium..... I TORO i oid 75
SelmerateB CrCyaeneie eee I 46.0 | Ibid., 76
Isoiresats@nléansie. a= ea2 I 10.7 Ibid., 76
Rhone at Geneva......../: I 16.8 | Ibid., 76
Kentucky River, Frankfort .| > 1 Ro Ibid., 66
Cumberland at Nashville. . . I 10.6 Tbid., 66

The following table of averages suggests the influence of the
terrane on the run-off.

TABLE XXIII

Terrane No. of Analyses | Ca/Mg
eiMeStONeSieeee ween eee 7 15
Phy llitesis ates setters ters 5 2.37 Hanamann
Crystallineia ee eee II 3.36
Dolomites and shales ..... 20 2.91
Sandstone muses amet 66 26
ID olomitemees tea see 24 Om

The influence of climate on the calcium magnesium ratio of
streams.—Clarke! has pointed out that the streams of humid,
more or less forest-covered portions of North America are normally
carbonate waters in which calcium is the principal base, while
rivers in arid climates tend to be high in sulphates and chlorides
in which calcium may or may not be the principal base. The

tF, W. Clarke, Bull. 330, U.S.G.S., 72.

EVOLUTION OF LIMESTONE AND DOLOMITE 419

magnesium content of streams in arid climates tends to be high,
as shown by the following table.
TABLE XXIV
Catcium MaGNEstumM RATIO IN STREAMS OF ARID COUNTRIES

Streams Mg Care| Source
SacramentopRes Caley ry eter. I anton Clarkes Bull9330, Ues:Ges-.0/0
Sanulvonenzopen Cally te oa. age I 2.01 | Ibid., 70
SantayClanas Rew Calle ac nema a I Dex || Lhitelee, 7)

IMassiont Greeks Cale eo ecient I 2.1830) Lids, 70
ColdiSprmer@reekes Cala a. I 2.00 || Lbid., 70
WonouGreekel Calla aiae) eaten a © I 2 ATA Ot 70
Santa Ynez R., Gibraltar, Cal..... I 2.93 | Lbid., 70
(@hrehhipRe wl ceriawin arsine ott. I 1.8r | Lbid., 70
Chelios cra acta rege sense ar. I Taso) |e lbid.. 70
@lreliigRewAlc eriate tress fcaceroaysies I 2.88 | Ibid.,-70
TAZ OSWRGHMA NG Kena wr sctey tales ecstasy Si I 4.67 | Ibid., 69
IRGOR GRAIG Cs eXt othe. cag ches ster Tee 20 llbid=. 66)
REcosm Rue Nees s asin hotness Tey eae aie LOtde 00
Colorado River, Yuma, Ariz....... I 3.30 | Ibid., 69
(GilaehRunver-wATizg-c cision a esate: Ty ese 7a bra. 206
Salle River, NAVAw eu cube concen cde I DF Oise |yelbtd 800
ColoradouwRe, Austin; Tex... 55... I 3 | Dole, W.S. Paper 236, U.S.G.S.,
56
Rio Grande; Waredo, Vex... 2.0. ..- r | 4.5 | Ibid., 96
IBIAOS, WWENGO), IMGs os coe ogame nos Te Omceun|ellO7deeeG@

Where the terrane is exceptionally calcareous, however, cal-
cium may predominate considerably. The insolubility of lime
under arid conditions is illustrated by Hilgard’st composite soils,

Table XXV.
TABLE XXV

Catcium MaGNEstumM Ratio IN Sorts FROM ARID AND Humip REGIONS

Soil ; Mg Ca
Average of 466 soils from humid regions of southern part of
OTe CS Eat esiimare meme ct mek oe tts c Wu wmanha a malt ndie a Manoten Als late I sts)
Average of 313 soils from arid portions of United States....... I Ts

Apparently soils in arid climates contain about twice as much
calcium in proportion to magnesium as those of humid climates.
Influence of the belt of cementation on the calcium magnesium
ratio of underground waters——The materials carried in solution
by underground waters in the belt of cementation undergo various
abstractions and additions on their way to the sea. The cements

1E. W. Hilgard, Bull. No. 3, U.S. Weather Bureau (1892), 30.

420 EDWARD STEIDTMANN

of the limestones and sandstones undoubtedly contain much
more calcium than magnesium, although no estimate of their rela-
tive proportions can be given. Since the ratio of calcium to mag-
nesium in the average sandstone (Clarke’s) is 5.50 to 1, it is prob-
able that the ratio of calcium to magnesium of the cementing
materials in the sandstones is even higher.

The solutions which percolate through shales, clays, and other
silicates are known to suffer an exchange of bases and other
changes through the interaction of water solutions and silicates.
This interaction is dependent upon the condition of chemical
equilibrium between the solutions and the silicates. Kiilenberg’
and other experimenters have shown that soils absorb more potassa
and magnesia than lime and soda. The great absorption of
potassa by soils and the very slight absorption of soda has been
interpreted as the reason why land plants utilize potassa more

largely than soda.
TABLE XXVI

RATIO OF CALCIUM TO MAGNESIUM IN THE CHLORIDE WATERS OF THE DEEP COPPER
MINES OF MICHIGAN, AS COMPARED WITH THE SURFACE WATER

Deep Mine Waters Ratio of Ca: Mg
CrandgEleventicalshant meccw cua ets caer 62
Tamarack Junior (very strong)........... 310
(Cems tlalis Boles ape wos ca Gee aowud es 412
CYandeHesr7thileviele eS aeene re et: 475
Ramiarack qs OOsec tame rere semen TE (trace of magnesium present)
Mrimountain. othwlevelk | 7145.2. oe ace (trace of magnesium present)
Quincy minel(very Strong) sees ea. | 4,300
(Gyiunbavey/iwabhoVes ye Akins) Crees Abie Se AH yoo 3,078
SUPA ceswa tenet mn art iui eaten ARS

The influence of silicates in the belt of cementation on the
calcium magnesium ratio of underground waters is suggested by
a comparison of the calcium magnesium ratio of the surface and
deep waters of the copper mines of Lake Superior. The deep
waters are probably the modified residuum left from the cycle
of deposition which developed the ores and gangue minerals.
The result of cementing processes has been a concentration of
calcium in the solutions. Magnesium has evidently been forced
out of solution by the conditions of chemical equilibrium. See
Table XXVI.

* Mittcil. d. Landw. Centralvereins fiir Schlesien, Heft 15, p. 83, quoted by E. C.
Sullivan, Bull. 312, U.S.G.S., 16-10.

EVOLUTION OF LIMESTONE AND DOLOMITE 421

The relative absorptive power of the crustal materials for
calcium and magnesium has not been adequately determined.
Certain it is that many shales, slates, muds, and soils have a higher
content of magnesium than of calcium. The probability that
the selective withdrawal of muds from the lands to the deep sea
has involved a selective loss of magnesium from the lands has been
pointed out on p. 414.

The average calcium magnesium ratio of the solutions contributed
to the sea.—The Mississippi‘ at New Orleans, which may be regarded
as a mixture of the waters from the average Paleozoic terrane,
shows a ratio of calcium to magnesium of 3.81 to 1. The average
calcium to magnesium ratio of 73 streams east of rooth meridian
of the United States observed daily at 94 stations for a period of
one year is about 4 to 1. In Sir John Murray’s well-known com-
position of 19 streams of the world, the calcium to magnesium
ratio is 4.4 to 1. From Mellard Reade’s? data, the ratio of cal-
clum to magnesium in the materials of chemical denudation is
8.25 to 1. A better based figure for the average composition of
the streams of the earth is that recently made by Clarke. The
ratio of calclum to magnesium in Clarke’s average as previously
cited is about 6 to I.

While the ratio of calcium to magnesium of the solutions con-
tributed to the sea is higher than it would be if the lands had the
composition of an average igneous rock, the largest streams do
not seem to show the high calcium to magnesium ratio that one
would expect from the amount of limestone on the continents.
However, the Mississippi is about the only large stream whose
composition is accurately determined. It may be that the large
amount of suspended material in rivers tends to lower the calcium
ratio, since the muds, particularly of humid climates, tend to be
high inmagnesium. The arid nature of about one-fifth of the land
area is another factor which may cause a retention of calcium by
the land. If this hypothesis is correct, a compensating increase
mn the calcium ratio of rivers will be contemporaneous with oceanic
expansion.

RB. Doles Wes. Paper 230, US.GiS., £7.

2 Mellard Reade, Chemical Denudation in Relation to Geologic Time (1879), 1-61.

3F. W. Clarke, Study of Chemical Denudation, Smithsonian Institution, Vol.
LVI (2910), No. 5, p. 8.

422 EDWARD STEIDTMANN

Conclusion: Increase of the ratio of calcium to magnesium in
rivers with geologic tume.—Evidence has been presented to show
that the ratio of calcium to magnesium of stream water is influenced
primarily by the ratio of calcium to magnesium of the terranes
which they drain, being generally higher than that of the terranes.

Climate exerts a modifying influence. Aridity lowers the
ratio of calcium to magnesium of the stream waters, causing a
concentration of calcium in the soils, while humidity has the
opposite effect. The interaction of the salts carried in solution
by streams and ground waters with the land materials, particu-
larly those high in clay, results in a greater loss of magnesium from
the waters than of calcium, thus tending to increase the ratio of
calcium to magnesium of the streams and ground waters.

Regardless of any theory of the origin of the earth, geologic
evidence points to the igneous rocks as the primitive source of the
sedimentary rocks. The streams of the primitive lithosphere,
therefore, probably approached in their chemical character the
present streams, flowing over crystalline rocks, subject to climatic
and other modifications. Such streams have a ratio of calcium
to magnesium approximating 3 to 1. The best figure given for
the average calcium to magnesium ratio of the streams of the
world is approximately 6 to 1. The latter figure probably should
be greater, considering the abundance of limestone on the conti-
nents. Little doubt therefore remains that the proportion of
calcium to magnesium in the streams is now higher than in earlier
stages of the earth’s history. It is also highly probable that the
increase in the ratio of calcium to magnesium in the rivers has
been continuous with geologic time, because of the progressive
increase in this ratio in the limestones deposited during geologic
time, and because of the selective deposition of limestones on the
submerged continents.

STATEMENT OF HYPOTHESIS

The conclusion has been reached that dolomites develop pre-
dominantly in the sea rather than by the metamorphism of lime-
stones after their emergence from the sea. Hence the decline in
the percentage of dolomite in going up the geologic column seems

EVOLUTION OF LIMESTONE AND DOLOMITE 423

to indicate that less and less dolomite was deposited in successive
periods of geologic history, thus pointing to a progressive change
in the conditions of deposition. Of the four factors controlling
the deposition of carbonates in the sea, viz., temperature, pressure,
life processes, and chemical composition, only the last two show
any probability of progressive change with time. There is no
evidence for a change in the nature of life processes. There is
evidence for a change in the chemical composition of the sea,
specifically for an increase in the ratio of calcium to magnesium
contributed to the sea from the lands, which will appear from the
following considerations. The present lands contain a much
larger proportion of limestones than could be gotten by redis-
' tributing a granite or basalt, generally accepted as being equiva-
lent to the materials of the primitive lands. It is inferred from a
consideration of the relation between the composition of river
waters and the terranes which they drain that the present rivers
have a higher ratio of calclum to magnesium than those of the
primitive lands.

The accumulation of limestones on the lands of increasing
calcium content, with time, seems to be related to a reworking of
the land over and over again along certain selective lines. A
higher percentage of calcium than of magnesium tends to be lost
from all kinds of rocks when subjected to all kinds of metamorphic
processes. Hence there is a continuous selective removal of cal-
cium from the lands of the sea, as is evidenced by the fact that
the ratio of calcium to magnesium of rivers tends to be higher
than the ratio of calcium to magnesium of the lands which they
drain. This involves a selective retention of magnesium in the
clastics. ‘The transportation and deposition of clastics is at a
maximum during periods of continental expansion and at a mini-
mum during periods of continental submergence. The clastics
are therefore deposited mainly on the margins of the continents
and in the deep sea. Those deposited in the deep sea are per-
manently lost to the lands and with them goes a selective loss of
magnesium from the lands. The carbonates, calcium and mag-
nesium, are deposited mainly in shallow epicontinental seas during
periods of continental submergence, in consequence of organic

424 EDWARD STEIDTMANN

and inorganic agencies. The percentage of calcium carbonate
which is deposited from the sea is higher than that of magnesium
carbonate, and from field and laboratory evidence it is inferred
that the proportions of the two carbonates deposited are in some
direct relation to their proportions in the rivers which bring them
to the sea. Hence, there is a selective return of calcium to the
lands.

It is therefore inferred that the evolution of the limestones
and dolomites has been in response to the gradual increment of
calcium over magnesium in the solutions contributed to the sea,
a tendency arising primarily from physical-chemical causes, aided
or accelerated by organic processes working harmoniously with the
inorganic environment.

For illustration, it may be assumed that sedimentation began
during continental expansion when the lands had the composition
of an average igneous rock. From the known results of meta-
morphic processes, it would follow that the solutions contributed
to the sea had a higher calcium to magnesium ratio than the lands
from which they were derived, and that the residuals had a higher
proportion of magnesium to calcium than the original rocks. A
part of the residuals, particularly the muds, are subject to selective
transportation to the continental margin and the deep sea. Accept-
ing the hypothesis of the permanence of oceans and the continents,
those deposited in the deep sea are permanently removed from
the continents. The calcium and magnesium salts interact with
the materials of the ocean bottom and enter into the constitution
of silicates, carbonates, and other compounds, or they may inter-
act with other constituents in the water, and be precipitated prin-
cipally as the carbonates. Magnesium would tend to interact
more actively with the muds of the bottom than calcium. Calcium
would tend to be more insoluble in shallow water than in the
deeps, while the opposite tendency probably characterizes mag-
nesium. Magnesium salts in general are more soluble. in sea
water than calcium salts. Organic precipitation, apparently only
an adaptation to conditions of chemical equilibrium already
existing, would be particularly effective in abstracting calcium
from warm, shallow seas. The relative solubility of the materials

EVOLUTION OF LIMESTONE AND DOLOMITE 425

precipitated would depend upon conditions of equilibrium con-
trolled mainly by temperature, concentration, the amount of
carbonic acid in the air and ocean, and organic processes. As a
result of the preceding selective influences, the calcium to magne-
sium ratio of the limestones would tend to be higher than that of
the solutions contributed to the sea. However, contemporaneous
with continental expansion, as at the present time, limestone deposi-
tion would be at a minimum, which might involve a concentration
of calcium in the sea until more favorable conditions of precipi-
tation arise. Limited areas of shallow water, vigorous erosion,
continental climates, and other supplementary conditions make
periods of continental expansion more favorable to the deposition
of clastics than limestones.

Gradually the lands waste away, the ocean advances over the
continents, partly in consequence of fill from the land, in part,
perhaps, -as a result of secular earth movements which cause a
shallowing of the ocean basins. The rivers carry less and less
débris to the sea, and deposit it farther and farther inland from
the margin. On the submerged continental areas, covered by
shallow seas, which now may be three or more times as extensive
as they were during the preceding period of continental expansion,
chemical and biochemical processes combine in making this an
era of limestone building. From experimental and field evidence,
the inference is drawn that the ratio of calcium to magnesium in
the deposited limestones is influenced primarily by their respective
rate of contribution from the land, and modified by selective organic
and inorganic agencies working to a common end.

As postulated by Chamberlin, with the expansion of the seas,
the zonal, diversified continental climates tending toward aridity
and refrigeration yield to more uniform, mild atmospheric con-
ditions. A widening of the life zones favorable to limestone
deposition follows. Thus in the Devonian, corals thrived in the
now ungenial climate of Hudson Bay. With world-wide climatic
moderation, a new condition of equilibrium is established between
the carbon dioxide of the sea and air. Warm water absorbs less
carbon dioxide than cold. The sea begins to contribute its excess
of carbon dioxide to the air, in consequence of which the calcium

426 EDWARD STEIDTMANN

of the sea becomes still more insoluble. The atmospheric condi-
tions and the land relief favor the floral blanketing of the earth,
thus stimulating chemical denudation and creating an effective
screen for the retention of clastic materials on the land.

As the waters again withdraw from the lands into the hollows
of the sea in response to secular earth movements, they leave
composite sediments behind them whose ratio of calcium to mag-
nesium is higher than that of the average igneous rock. With
topographic rejuvenation, the muds are again carried toward the
margin and to the deep sea, or possibly at times directly to the
deep sea as suggested by submerged stream channels, the con-
tinuation of existing streams which in some cases extend to the
margin of the deep sea. Various parts of the earth are subjected
to regional metamorphism and secular uplift, particularly the
continental margins, causing selective removal of calcium and
the concentration of magnesium in the residuals. The marginal
sediments, dominantly clastics, by virtue of position, relief, and
a combination of other factors, are in a most favorable position
to be removed from the land and swept into the deep sea, where
they would be permanently withdrawn from the land. The depo-
sition of clastics is again at a maximum, that of limestones at a
minimum. Asthe pendulum swings from one extreme to another,
it marks a curve of progressive change in the composition of the
lands and in the ratio of calcium to magnesium in the salts con-
tributed to the sea, consummated by an accumulation of limestones
on the continents of progressively higher calcium content, both a
reflex and a cause of changes in the land composition, and by the
withdrawal of the complementary muds toward the margins and
the deep sea, slow during periods of oceanic expansion, but tre-
mendously accelerated during periods of oceanic retreat, selective
concentration of magnesium in the deep zones of high temperature
and pressure, in the clastics, and in the sea—a never-ending cycle
of selective causes and cumulative effects, recalling the words
of Faust:

Wie alles sich zum Ganzen webt,
Eins in dem anderen wirkt und lebt.

EVOLUTION OF LIMESTONE AND DOLOMITE 427

SUMMARY

The problem under discussion is, Why does the dolomite con-
tent of the geologic column decrease with time? Is it due to a
secondary alteration of limestone after emergence from the sea,
roughly proportional to time, or is it due to a gradual decline in
the primary development of dolomite in the sea? If the latter,
what factors controlling the deposition of dolomite have changed
during geologic time, temperature, pressure, life processes, or the
chemical composition of the sea ? .

The conclusions reached are: dolomite develops predominantly
in the sea, therefore the decrease in the dolomite content of the
sediments in going up the geologic column is mainly due to a
decrease in the proportion of dolomite developed in the sea with
time.

The factors of deposition whose progressive change has probably
controlled the decline of dolomite development in the sea are life
processes and the chemical composition of the sea. There is no
definite evidence for a change in the nature of the life processes
in their relation to dolomite deposition. There is evidence for a
change in the chemical composition of the sea; namely, the fact
that the present ratio of calcium to magnesium of the streams is
probably more than twice that of streams draining crystalline
terranes, comparable in composition to the primitive lands. Accept-
ing uniformitarianism, it follows that the present streams have a
much higher ratio of calclum to magnesium than the primitive
streams. It has been indicated that solutions high in magnesium
and low in calcium are more favorable to the development of
dolomite than those which are low in magnesium and high in
calcium. It is therefore highly probable that the chemistry of the
primitive sea was more favorable to the deposition of dolomite
than the present ocean.

The increase in the proportion of calcium to magnesium in the
streams is believed to be due to selective processes whose effects
have been cumulative with time. Rock alterations tend to result
in a higher percentage loss of calcium than of magnesium, the
materials lost being largely transported in solution to the sea.

428 EDWARD STEIDTMANN

A higher percentage of magnesium is retained in the residuals of
rock decay than calcium, but erosive processes are constantly
removing the residuals toward the margins of the lands, and
during periods of continental expansion a considerable proportion
is swept into the deep sea and permanently lost from the lands. In
consequence of a combination of organic and inorganic agencies,
the maximum deposition of limestones and dolomites is on the
submerged lands during periods of oceanic expansion. ‘The per-
centage of calcium precipitated is higher than that of magnesium,
but the proportions of calcium to magnesium which are precipi-
tated bear some direct relation to their ratio in the rivers which
bring them to the sea. With the progressive elimination of
clastics and magnesium from the lands with geologic time, and in
their place the gradual accumulation of calcium in the form of
limestone, the proportion of calcium to magnesium contributed by
rivers to sea has increased with time.

The writer is indebted to C. K. Leith for suggestions and
criticisms.

DIFFERENTIATION OF KEWEENAWAN DIABASES IN
THE VICINITY OF LAKE NIPIGON

E. S. MOORE
The Pennsylvania State College

In recent numbers of Economic Geology two papers have been
published describing the differentiation products of the quartz-
diabases of the Nipissing District, Ontario. Since these diabases
have generally been regarded as of Keweenawan age, certain
differentiation products of the Keweenawan diabases in the vicin-
ity of Lake Nipigon are also of interest.

On the north shore of Lake Superior and extending northward
beyond Lake Nipigon there are masses of diabase and gabbro
which intrude the older crystalline rocks in the form of batholiths,
dikes, and bosses and the sediments in the form of the “Logan
sills.” Although there are differences of opinion regarding the
geological age of these rocks, the writer concurs with those who
regard, as closely related in origin, the great amygdaloidal basalt
flows of Keweenaw Point, the Duluth gabbro, the ‘Logan
sills,” the Sudbury Nickel eruptive, and the Cobalt diabases, as
well as many other masses of diabase in intervening areas. The
great igneous activity of this region seems to have been the result
of extensive crustal adjustment centered around Lake Superior
and diminishing in intensity as a greater distance from the center
was reached. It is probable that on the northern side of the Lake
Superior basin the intrusive masses were being injected into sedi-
ments which had already been formed while the alternate deposits
of sediments and lava flows were being deposited on the south
side and that a close relationship exists between all portions ot this
great series of sediments and extrusive and intrusive igneous rocks.

While a general description of the petrography of these rocks
is given here, the object of this paper is to call attention to certain

tW. H. Collins, Econ. Geology, V, No. 6, p. 538; R. E. Hore, ibid., VI, No. 1,
JO. Sits

429

430 E. S. MOORE

evidences of differentiation which have already been mentioned
by Dr. A. P. Coleman and the writer and to add additional notes
to the descriptions of this phenomenon.

PETROGRAPHY OF THE DIABASES

The Keweenawan rocks around Lake Superior have been
described petrographically in detail, by Irving, Bayley, Van Hise,
and many others. In the vicinity of Lake Nipigon the rocks are
in many respects similar to those around Lake Superior and they
have been described with less detail by Coleman, Wilson, and other
geologists. The greater portion of the shores and the islands of
this lake consist of basic rock, either diabase or gabbro. Thin
sections almost invariably show the ophitic texture more or less
well developed, and, although in many places the diabase grades
toward gabbro, the greater portion of the rock is diabase. In
the sills, diabase always seems to be found, and the same state-
ment may be made of the smaller bodies of the rock, while some of
the larger batholithic masses, which have suffered some differ-
entiation, more strongly resemble gabbro.

Structurally the rocks form bosses, large and small, batholiths,
or very large irregular masses, dikes, and sills. The dikes are
often large, as some were seen in the Onaman Iron Range area
150 ft. in width, and these seem to represent offshoots from the
main diabase mass in the vicinity of the lake. The sills, known
as the “Logan sills,” form beds from two to several hundred feet
in thickness. These masses lie between beds of sandstone, shale,
or dolomitic limestone, or between these sediments and the under-
lying Archean rocks, and in all cases studied they present evidence
of their intrusive character. Columnar structure is a character-
istic of nearly all of the larger masses, especially of the larger sills.

In macroscopical characters these basic rocks generally present
a monotonous appearance. They vary in grain from coarse to
medium fine and in color from brownish to nearly black. Some
of them weather rapidly to granular incoherent masses, and, in the
early stages of this weathering, they exhibit in many places cleav-
age surfaces with a bronze tint. In many cases the ophitic texture
is readily recognized in the hand specimen, but in the masses

DIFFERENTIATION OF KEWEENAWAN DIABASES A431

which tend to become coarse grained and to separate into little
aggregations of feldspar and magnetite this texture is lost to a
large extent and the rock becomes more like a coarse gabbro. In
one place on the shore of Lake Nipigon some sand was collected
which showed poikilitic texture where feldspars were inclosed in
augite.

In microscopical observations these rocks usually show labra-
dorite, augite, or diopside, and ilmenite or magnetite. Olivine is
widespread but is not always present and in specimens without
olivine quartz has been found, but it is lacking in many specimens.
Biotite appears in small quantities and titanite was found in one
section. Since the latter mineral occurs near a dike of acid rock
and is not commonly developed in diabases or gabbro, it is believed
to be due to the influence of this dike, as some of these acid dikes
carry titanite.

Although these rocks are on the whole comparatively fresh,
certain alteration products occur. The olivine frequently shows
serpentine and iron oxide as alteration products, and the augite
and diopside, although usually quite fresh, often contain second-
ary amphiboles and actinolite. In a specimen from ‘ Haystack
Mountain,” north of Lake Nipigon, a crystal of magnetite occurs
partially surrounded by a mass of actinolite needles which, on
revolving the stage of the microscope, show
rotary extinction (Fig. 1). These needles
seem to be the product of alteration of an
augite crystal whose growth began around
the magnetite and they resemble similar
fibrous growths which W. S. Bayley de-
scribes as occurring around magnetite in

Fic. 1.—Magnetite par-
- ‘ i tially surrounded by augite
the basic rocks of the Lake Superior region, which has altered to actin-

although he does not ascribe a secondary lite needles (greatly en-

origin to them.t In a specimen from the jarged):

shore of Lake Nipigon, opposite “‘Two Mountain” Island, the

diopside and magnetite are intergrown to some extent and the

latter sometimes occurs as a fringe along the border of crystals of

the former. Although much of the magnetite associated with the
t Journal of Geology, I, 702-10.

432 E. S. MOORE

diopside is primary, some crystals of the diopside which are par-
tially altered to secondary amphiboles contain also undoubted
evidence of alteration to magnetite and hematite. While these
are unusual alteration products for diopside, analyses of this
mineral from gabbro sometimes show as much as 15 per cent of

Fic. 2.—Photomicrograph of diabase showing ophitic texture (crossed nicols;
X40).

iron oxide. The pyroxene is readily recognized as diopside by
its characteristic color and extinction angles.

In texture the ophitic character is usually well developed, as the
labradorite generally occurs as lath-shaped, nearly euhedral crys-
tals, which penetrate the augite and diopside (Fig. 2) and in some
cases are surrounded by them, giving also a poikilitic texture.
The rock might therefore be called, to apply the term suggested

DIFFERENTIATION OF KEWEENAWAN DIABASES 433

by A. N. Winchell for such textures, a poikilophitic rock.t In
sections of diabase from “Haystack Mountain” the augite is
frequently twinned with two members, and instead of the usual
stout crystal it occurs in long, narrow forms, somewhat lath
shaped, and in this respect resembling the feldspars.

DIFFERENTIATION PRODUCTS; PEGMATITE DIKES

The differentiation products of the Keweenawan rocks of the
Lake Superior region have been frequently mentioned. Clements
states that the gabbro in Minnesota shows undoubted evidence of
differentiation in the large masses of anorthosite and the patches
of magnetite and titaniferous iron ore.2, W. S. Bayley describes
peridotites and pyroxenites as very basic phases of the gabbro in
his description of the Lake Superior region.

From Lake Nipigon A. P. Coleman describes picrite and other
very basic phases of the diabase and also certain acid dikes which
are described as post-Keweenawan but closely related to the Kewee-
nawan basic rocks and perhaps differentiation products of them.‘
These rocks are described as having a pegmatitic or micropeg-
matitic texture and as having the composition of granite or grano-
diorite.

In ‘Haystack Mountain” north of Lake Nipigon the writer
found similar dikes and from their relationships suggested that
they represented an acid phase of the diabase magma.’ The later
observation of similar dikes in the Duluth gabbro near Duluth,
Minnesota, confirmed the belief that these rocks are differentiation
products of the diabases and gabbros.

The rock at “‘Haystack Mountain” is a coarse diabase, rather
gabbro-like, and shows small, dark patches of titaniferous magnet-
ite and in places lighter blotches consisting largely of feldspar.
The magnetite is sufficiently abundant in part of the hill to influence
the compass so that prospectors were led to record mining claims

t “Use of ‘Ophitic’ and Related Terms in Petrography,” Bull. Geol. Soc. Am.,
XX (1010), 661-67.

2 U.S. Geol. Survey, Monograph XLV, 397-424.

3 Jour. of Geology, II (1894), 814-25.

4 Bureau of Mines of Ontario, XVII (1908), 163-64.

5 Ibid., XVIII (1907), 162.

434 E. S. MOORE

upon it. Besides these small segregations of feldspar there are
irregular dike-like masses of similar, light-colored rock and a few
fairly distinct dikes, all of small size and varying from one-half
inch to a foot in width. These dikes are rather fine grained and
in thin section show the following characters. The texture is
usually micropegmatitic and one section is composed of about
60 per cent feldspar, 30 per cent quartz, 10 per cent hornblende,
and a little magnetite and hematite. The feldspar is chiefly
orthoclase with a little albite and the rock is a granite. Another
section contains very little hornblende and a little epidote, the
rock being composed almost entirely of feldspar in the proportions
of 65 parts orthoclase to 35 parts plagioclase. This rock is a
syenite grading toward a monzonite. Still another section is
from a dike which might be regarded as a monzonite. It contains
a little enstatite, epidote, and titanite, while the greater portion
of the rock is feldspar and in the proportions of about 66 per cent
albite and oligoclase and 34 per cent orthoclase. A fourth section
is from an augite-syenite dike in which the orthoclase makes up
75 per cent and the sodic variety 25 per cent of the feldspar. There
are a good many small augite crystals and the micropegmatitic
texture is well developed. A section of a dike from near ‘Two
Mountain” Island is also an augite-syenite. :

The most interesting dikes in the region are those occurring
on Flat Rock Portage near the south end of Lake Nipigon. At
this point a large mass of rock, described by Coleman as a sill of
epi-basalt or fine-grained diabase-porphyrite, is cut by a pegmatite
dike varying in width from three inches to one foot. Where the
diabase has suffered columnar jointing the fissures have filled
with acid rock similar to the flesh-colored or pink dikes described
above (Fig. 4). The surface of this sill is flat and fine grained, and
when the glacier passed over it interesting chatter-marks were
left. The pegmatite dike is medium coarse grained, flesh colored,
and appears to be composed very largely of feldspar. Under the
microscope the pegmatitic intergrowth of various minerals and the
graphic intergrowth of quartz and feldspar are well developed.
The rock consists of quartz in proportion of ro per cent, epidote
to per cent, and sodium-calcium feldspar 80 per cent. The

DIFFERENTIATION OF KEWEENAWAN DIABASES 435

feldspars show a wonderful development of the zonal structure
(Fig. 3). In the rapid growth of the crystals the zones of calcium-
and sodium-rich material have developed mostly at their ends,
and they have thus been drawn out to excessive linear proportions.
The indices of refraction indicate that the most calcic feldspars
form the central zone and the more sodic follow outward. The
usual order of rate of weathering of the sodic and calcic feld-

Fic. 3.—Photomicrograph of a section from a pegmatite dike at Flat Rock Portage
showing unusual development of zonal structure in sodium-calcium feldspar (crossed
nicols; X4o).

spars does not hold in many of these crystals, as the second zone
even with lower index of refraction often shows much more exten-
sive alteration than the central zone. The alteration products
are epidote and a mineral or mixture of minerals which has yellow-
ish polarization colors and is believed to be epidote, kaolin, and
zeolites. A peculiar influence of the pegmatitic intergrowth of
the minerals is the crystallization of epidote in some of the zones

436 E. S. MOORE

replacing the feldspar. This arrangement was seen where the path
of an epidote crystal was cut across by that of the growing, zonally
built feldspar. In a couple of cases a group of epidote crystals is
crossed by feldspar, but the simultaneous extinction of all parts of
the epidotes shows them to be parts of the same crystal and in one
case particularly a portion of the epidote crystal has passed through
the feldspar, forming one of the zones of the crystal. In these cases
the epidote is undoubtedly primary, although considerable second-
ary epidote occurs from alteration of the feldspars.

An interesting example of a crushed feldspar is seen in this
section where the crystal has been broken into slivers and the
fragments surrounded by quartz. This must have been due to
pressure, although the rock as a whole does not show evidence
of excessive pressure beyond the undulatory extinction of some of
the quartz grains.

In his description of the copper-bearing rocks of Lake Superior,
Irving describes some sections from dikes of red rock in the Duluth
gabbro which would indicate that they are probably similar to
those dikes described above.*

These acid dikes appear to be differentiation phases of the
Keweenawan diabases and gabbros because they occur, with one
exception, in these rocks only, and, so far as observed, only in the
larger masses and not in the thin sills which are too small to pro-
duce them by differentiation. This one exception is a dike 30
inches wide cutting quartzite and the overlying diabase near
Ombabika Narrows.? This dike might be due to the rising of the
liquid from some large diabase mass below through a fissure extend-
ing into the overlying rocks. There are no other bodies of acid
rock in the region later in age than the Keweenawan diabases, and
the pegmatitic and micropegmatitic textures suggest end phases
of a magma. These dikes probably fill crevices in the diabase
formed in the solidified exterior of a large mass, due to adjustment
of pressures during processes of cooling, and the acid material
rose from the still hot and more acid lower portions of the mass.
The tact that these dikes are so much more basic on the whole than

U.S. Geol Survey, Monograph V, 119-20.

2 Coleman, Bureau of Mines of Ontario, XVII, 164.

DIFFERENTIATION OF KEWEENAWAN DIABASES 437

the aplites of the Cobalt area may be due to the tact that the magma
from which they separated was on the whole more basic. The
ophitic texture of the diabases indicates 2 magma early saturated
with calcium. The alkalies, being in small quantity, were mostly
left over until the end of the crystallization period and then united
with the remaining aluminium and silica to form potassium or sodium
feldspars, while the small excess of silica occurring in a few places

Fic. 4.—Acid dikes filling columnar joint fractures in diabase.

went to form quartz. It is thus assumed that the magma became
saturated with the more basic materials first, and the remaining acid
materials, still liquid, were in some cases crowded toward the lower
and central portion of the mass to escape into the fissures when
opened, and form dikes. ;

In the case of the pegmatite dike in which the feldspar is largely
calcic and occurs with the silica, it is probable that the excess of
magnesium and iron caused the rocks to become saturated with

438 E. S. MOORE

these elements, and the augite and olivine, separating out earlier,
caused some of the calcium and aluminium to be left over to enter
the dike.

It is interesting to note that in the Sudbury and Cobalt areas,
where the Keweenawan rocks have suffered very great differen-
tiation compared with that in the Lake Nipigon region, there are
extensive ore bodies connected with them, while there is nothing
but a little iron ore in the Nipigon region, and this occurs at the
contact with sediments and may be leached from them.

While differentiation of magmas and thus the separation of the
metals, as well as other elements, from the magmas, may be only
one factor in the development of mineral veins as well as mag-
matic segregations, it seems probable that all data collected on this
subject will show this is one of the important factors. Other
things being equal, if the igneous rocks are the source of the metals,
those magmas which show the greatest differentiation should be
the most favorable for the production of ores, whether they supply
metal-bearing solutions directly to the veins—a process quite
conceivable in some cases—or whether they cause segregation of
the metals so that they can readily be dissolved by meteoric waters
in sufficient quantities to form ore deposits in veins.

GENERA OF MISSISSIPPIAN LOOP-BEARING
BRACHIOPODA

STUART WELLER

INTRODUCTION

The correct specific determination of the loop-bearing brachio-
pod shells of the Mississippian faunas has always been attended
with difficulty. This condition led the writer to undertake a
critical study of a large amount of material, in order to determine,
if possible, the true criteria for the determination of species. In
this study the internal characters of the shell, as well as the exter-
nal configuration, have been taken into consideration.

In the earlier literature all the shells of this type were included
in the genus Terebratula, but since the appearance of Hall and
Clarke’s great work on the Genera of Paleozoic Brachiopoda,’ it has
been the usual custom to refer all of them to the genus Dielasma,
although Girty has described one form as a member of the genus
Harttina” As a result of the present investigation, however, it
has been found that forms which have been commonly included in
a single genus, and in some instances, even, forms which have been
referred to a single species, in reality represent several perfectly
distinct generic types. The method used in the investigation is
that which has been formerly used in the study of the Rhyncho-
nelloid shells. Specimens have been ground from the posterior
extremity and at short intervals the ground surface has been pol-
ished and a careful drawing made of the cross-section of the shell
parts shown. From such a series of cross-sections of any shell it
is easy to recognize the character and position of the internal
lamellae, such as the median septum, the hinge-plate, the socket-
plates, the bases of the crura, etc. In the course of the study it
has been shown that the characters which can be considered as of

t Paleontology of New York, Vol. VIII, Parts x and 2.

2 “Farttina indianensis Girty,’’ Proc. Nat. Mus., Vol. XXXIV, p. 203.

439

440 STUART WELLER

generic value in these shells are to be found in the rostral portion
of the brachial valve. Six and possibly seven good generic groups
have been recognized, and will be defined here.

DIELASMA King

Description.—Shell terebratuliform. Pedicle valve with or
without a median sinus, the beak strongly incurved, the foramen
large and encroaching upon the umbonal portion of the valve;
internally with well-developed dental lamellae. Brachial valve
usually without mesial fold; internally the crural plates are sepa-
rate from the dental socket-plates, they diverge from the apex of
the valve with an elongate attachment to the inner surface of the
valve, the free portion of the brachidium is short, with diverging

MW. (UI WH, Nat, YD NS

Fic. 1.—A series of fourteen cross-sections (23) of the rostral portion of the
brachial valve of Dielasma formosa Hall.

descending lamellae; between the crural plates for the full length
of their attachment to the inner surface of the valve, is a concave,
transverse plate for muscular attachment, which joins the inner
surface of the crural plates a little above their base; this plate
rests against the inner surface of the valve along the median line
for a portion or the whole of its length, or it may be free throughout;
when attached along the median line a pair of slender cavities,
triangular in cross-section, converge from the general cavity of
the shell toward the beak, but when the transverse plate is not
attached along its median line there is a single, broad and low
cavity beneath the plate, extending toward the apex; anteriorly
this plate extends to a greater or less distance beyond the attach-
ment of the crural plates and is pointed, rounded, or emarginate
in front; its surface is marked by concentric wrinkles parallel with

MISSISSIPPIAN LOOP-BEARING BRACHIOPODA 441

its anterior margin which are usually discontinuous along the
median line.

Remarks.—The genus Dielasma was established by King with
Terebratula elongatus Schl. as genotype, and although he defined
the genus primarily upon the presence of prominent dental lamellae
in the pedicle valve, and on the form of the loop, his illustrations
of the internal casts of the species under the name Epithyris elongata’
show that the crural plates are separate from the socket walls, one
of the most essential features of Dielasma as here defined. David-
son’? gives illustrations of the same species which exhibit all the
essential generic characters of Dielasma most perfectly. The
interpretation of the genus by Hall and Clarke is identical with
that here given, but those authors included certain species in the
genus without sufficient investigation of their internal characters,
which are fundamentally different; it has in fact been the usual
custom among American workers, since the publication of Hall
and Clarke’s work, to refer all Mississippian terebratuloid shells
to the genus Dielasma.

In specimens preserved in the condition of internal casts the
generic characters of Dielasma are always very obvious, the posi-
tion of the crural lamellae, separate from the socket-plates, being
indicated by a pair of slits diverging from the beak of the brachial
valve; when the transverse muscle-bearing plate is attached along
its mesial line a second pair of diverging slits are present between
those formed by the crural lamellae, and the finger-like casts
of the slender cavities beneath the transverse plate are clearly
shown, whether they are actually present or broken off. In speci-
mens having the shell preserved the shell substance is frequently
translucent enough to show the position of the internal lamellae
as dark lines, in which case the genus can be recognized at once,
and when the shell is opaque it is usually easy to determine the
generic characters by the judicious use of a needle, without injur-
ing the specimen as to its external form and characters upon which
the various species are differentiated.

* Monog. Perm. Foss. England, Pl. 6, Figs. 37, 41 (1850).

2 Brit. Foss Brach., 11, Permian, Pl. 1, Figs. 18, 20.
3 Pal ae ven Ve th app. 203-04:

442 STUART WELLER

Genotype.—D. elongata (Schl.). Other species, D. formosa
(Hall), D. shumardianum (Miller), D. fernglenensis Weller, D.
burlingtonensis White.

GIRTYELLA Nn. gen.

Description.—Shell terebratuliform. The pedicle valve sinuate,
with a large, subcircular or subovate, oblique foramen which
encroaches upon the umbo; the brachial valve frequently sinuate
and often with a slight median fold in the bottom of the sinus.
Internally the dental lamellae are well developed in the pedicle
valve. In the brachial valve the socket-plates are joined by a
concave hinge-plate which is imperforate at the apex and is sup-
ported by a median septum; the inner sides of the dental sockets

OD a a
Neo Nt NL

Fic. 2.—A series of nine cross-sections (23) of the rostral portion of the shell
of Girtyella indianensis (Girty), three of which show both the pedicle and brachial
valves, the others showing only the structure of the brachial valve.

retreat from the margins of the valve anteriorly beyond the point
of articulation, and become the bases of the crura which are still
joined by the concave hinge-plate and are also supported by
lamellae resting against the inner surface of the lateral slopes of
the valve. The brachidium short, its free portion apparently
being like that of Dielasma and not reaching to the middle of the
shell.

Remarks.—Members of this genus have commonly been included
in the genus Dielasma, but they differ fundamentally from that
genus in the presence of a median septum supporting the hinge-
plate of the brachial valve, and in the origin of the bases of the
crura from the socket-plates. In his description of the species
which is selected as the genotype, Girty referred the form to the -
genus Harttina on account of the presence of a median septum in

MISSISSIPPIAN LOOP-BEARING BRACHIOPODA 443

the brachial valve, but the brachidium of Harttina is elongate,
like that of Cryptonella, reaching nearly to the front of the shell,
while that of Gzrtyella is short, like the brachidium of Dielasma.

Genotype.—G. indianensis (Girty). Other species, G. turgida
(Hall), G. brevilobata (Swall.).

DIELASMOIDES n. gen.

Description.—Shell terebratuliform. Pedicle valve bisinuate
toward the front in the genotype, the two depressions separated
by a low, broadly rounded mesial elevation; the foramen large,
oblique, encroaching wholly upon the umbonal region. Brachial
valve with a slight mesial flattening or depression anteriorly in the
genotype. Internally the dental lamellae are well developed in
the pedicle valve; in the brachial valve the socket-plates are sup-
ported at their inner margins by a pair of lamellae which pass
obliquely toward the floor of the valve to which they are joined

OCOWDQQyuvst

Fic. 3.—A series of seven cross-sections (X23) of the rostral portion of the shell
of Dielasmoides bisinuata n. sp., in the last three of which only the brachial valve is
shown.

near the median line; between these lamellae, the outer walls of
the valve and the socket-plates, are a pair of cavities narrowly
triangular in cross-section which expand anteriorly and open out
into the general cavity of the valve; the crura originate from the
anterior extensions of the inner walls of the socket-plates. Form
of the brachidium not known.

Remarks.—The characters of the rostral cavity of the brachial
valve in this genus differ from those of Dzelasma in the absence
of any special crural lamellae distinct from the socket-plates.
The two rostral cavities, narrowly triangular in cross-section, have
a superficial resemblance in the two genera, but the narrow base
of the triangle in this genus is formed by the socket-plate, while
in Dielasma it is formed by the basal portion of the crural lamellae,
and the special muscle-bearing plate between the bases of the
crural lamellae of Dielasma is absent in this genus. This form is

444 | STUART WELLER

perhaps to be compared with Girivella as the genus most closely
allied to it. If the concave hinge-plate of Girtyella, which is sup-
ported by a median septum, be depressed along its median line to
such an extent that the concave plate itself rests directly upon the
floor of the valve, the median septum being eliminated, then we
would have essentially the characters shown in this genus. The
bisinuate folding of the anterior portion of the pedicle valve may
be a generic character, but this cannot be determined from the
single species so far recognized.

Genotype.-—D. bisinuata n. sp., St. Louis (?) oolite, Lewis
County, Mo.

CRANAENA Hall and Clarke

Description.—Shell terebratuliform. Pedicle valve with or
without a median sinus and with well-developed dental lamellae

©) a, 7,
J wy ray We

Fic. 4.—A series of ten cross-sections (X23) of the rostral portion of the shell of
Cranaena iowensis (Calvin), from all but the Ae of which the pedicle valve has been
omitted.

Gt eS NS NS

Fic. 5.—A series of six cross-sections of the rostral portion of the brachial valve
of Cranaena sp. undesc., residual chest, Springfield, Mo.

of moderate length internally, the foramen large, oblique, and
encroaching upon the umbonal portion of the valve, the beak
incurved. Brachial valve without median fold, even in those
species with a well-defined sinus in the opposite valve, but some-
times with a slight mesial depression near the front margin; inter-
nally the well-developed socket-plates are connected transversely

MISSTSSIPPIAN LOOP-BEARING BRACHIOPODA 445

by a concave hinge-plate which is perforated at the apex of the
valve posteriorly; upon the inner or concave surface of the hinge-
plate a pair of ridges originate at or near the anterior margin of
the perforation and continue anteriorly across the plate, from the
front of which they are produced into the crura. These crural
ridges divide the hinge-plate into three equal divisions, or into two
equal lateral divisions and a broader central one, and in some
species the crural ridges are accompanied by similar ridgelike
thickenings upon the opposite side of the hinge-plate. The
brachidium short and Dielasma-like, not reaching to the middle
of the valve.

Remarks.—This genus differs fundamentally from Dvzelasma
in the origin of the crura from the thickened crural ridges of the
hinge-plate, rather than from crural lamellae resting upon the
inner surface of the valve, and in the absence of a special plate in
the brachial valve for muscular attachment, the muscles being —
attached directly to the inner surface of the valve. From Girty-
ella the genus differs in the perforation of the hinge-plate, in the
absence of a median septum in the brachial valve, and in the
origin of the crura from crural ridges of the hinge-plate rather than
from the anterior extension of the inner extremities of the socket-
plates.

Genotype—-C. romingerit (Hall). Other species, C. iowensis
(Calvin), C. n. sp., residual chert, Springfield, Mo.

HAMBURGIA N. gen.

Description.—Shell terebratuliform. Pedicle valve not sinuate
in the genotype and only known species, the foramen large, oblique,
encroaching upon the umbonal region; brachial valve without
fold or sinus. Internally the pedicle valve is supplied with well-
developed dental lamellae; the brachial valve with well-developed
socket-plates which retreat from the lateral margins of the valve
anteriorly beyond the articulation of the valves; they are con-
nected transversely by a deeply concave hinge-plate which is
separated from the inner surface of the valve by an exceedingly
low and broad cavity; upon the inner or concave side of the
hinge-plate a pair of ridges originate toward the apex and diverge

446 STUART WELLER

slightly while becoming stronger anteriorly, finally passing into
the bases of the crura; shortly in front of the point of origin of the
crural ridges on the hinge-plate the socket-plates are rapidly
reduced in height and soon become obsolete, beyond which point
the hinge-plate is not connected with the inner surface of the
valve, but becomes a concave plate joining the bases of the crura
and terminating anteriorly in a short distance. The complete
form of the brachidium is not known, but it is probably short,
not reaching the mid-length of the valve.

Remarks.—This genus is perhaps most closely allied to Cranaena,
from which it differs in the extreme concavity of the hinge-plate,
the cavity between it and the inner surface of the valve being
reduced in height, and in the absence of the perforation of the

VW NY.

Fic. 6.—A series of nine cross-sections (X 23) of the rostral portion of the brachial
valve of Hamburgia typa, n. sp.
hinge-plate at the apex, which is, perhaps, the most diagnostic
character. The genus is totally distinct from Dielasma, in which the
crural plates originate as ridges upon the inner surface of the valve
instead of upon the concave surface of the hinge-plate. The concave,
transverse plate between the bases of the crura is somewhat similar
in the two genera except that it is not connected along its median
line to the inner surface of the valve in Hamburgia, but in
Dielasma the inner surface of this plate furnishes attachment for
the adductor muscles, which is apparently not true in Hamburgia.

Genotype—H. typa, n. sp., Hamburg oolitic limestone of
Kinderhood age, Hamburg, III.

DIELASMELLA N. gen.
Description.—Shell terebratuliform, compressed. Pedicle valve
with well-developed dental lamellae of moderate length. Brachial
valve without median septum or true hinge-plate, the socket-

MISSISSIPPIAN LOOP-BEARING BRACHIOPODA 447

plates well developed, retreating from the lateral margins of the
valve anteriorly and becoming differentiated into two portions,
a basal portion which joins the inner surface of the valve and is
directed obliquely inward, and a distal portion which is abruptly
bent in a subgeniculate angle so as to be directed obliquely out-
ward; the portion included in the angular bend of the two plates
is produced anteriorly into the bases of the crura, and just before
the crura become free a narrow transverse band joins their bases.
The characters of the brachidium not completely determined, but
it is believed to be of the short, Dzelasma-like type. Shell
structure finely punctate.

Remarks.—In the arrangement of the internal features of the
apical portion of the brachial valve this genus is perhaps more
closely allied to Cranaena than to any other of the generic types
here recognized. It differs from Cranaena chiefly in the reduction

w we SE es male ba
rs i z = “SS”

Fic. 7.—A series of six cross-sections (24) of the rostral portion of the brachial
valve of D. compressa (Weller).

of the hinge-plate to a narrow, transverse band joining the crural
bases, while in Cranaena it is elongate, with a comparatively small
apical perforation, and with the crura originating as a pair ot ribs
diverging anteriorly from near the apex. The difference in shape,
viz., the compressed shell and the erect beak of the pedicle valve,
are other features which easily separate the members of this genus
from all species of Cranaena which have been recognized.
Genotype.—D. compressa (Weller). Glen Park limestone.

ROWLEYELLA n. gen.

Description.—Shell terebratuliform, with the valves subequally
convex. The beak of the pedicle valve perforated by a subcir-
cular foramen which encroaches wholly upon the umbonal region,
the delthyrium broadly triangular and wholly closed. Internally
each valve is supplied with a strong median septum which, in the
pedicle valve, reaches nearly to the center of the valve, that of
the brachial valve being somewhat shorter.

448 - STUART WELLER

Remarks.—The relationships of this genus cannot be certainly
determined from the material available for study. The general
contour of the shell at once suggests its affinity with the tere-
bratuloid, loop-bearing shells, as also does the character of the
foramen of the pedicle valve, and so far as it can be observed the
delthyrium and its covering. The shell structure has not been
certainly determined. Upon one example a punctate structure
is slightly suggested, but that characteristic structure of the tere-
bratuloids cannot be said to be demonstrated. The characteristic
of these shells which is most foreign to the terebratuloids is the
strongly developed mesial septum of the pedicle valve, which
evidently supports a well-developed spondylium, and the presence
of this character in association with a strong median septum in
the brachial valve suggests the family Pentameridae, but it has
not been determined that a cruralium accompanies this median
septum of the brachial valve. This feature of a median septum
in the pedicle valve has not been recognized heretofore among the
loop-bearing terebratuloids, although there is perhaps no reason
why it should not exist, but a median septum in the brachial valve
occurs in at least one genus of these shells.

In any event the characters exhibited by these shells exclude
them from any described genus among either the terebratuloids
or the pentameroids. The presence of a pedicle median septum
is sufficient to differentiate the genus from any other of terebratu-
loids, if indeed it be one of these shells, and the characters of the
foramen and delthyrium differentiate it from any pentameroid.
The shell perhaps agrees most closely in the sum of all the char-
acters present with the spire-bearing Camarophorella, but there
is no evidence, in the specimens observed, of the presence of a
brachial platform associated with the median septum of that
valve, as is true in Camaro phorella.

Genotype.—R. fabulites (Rowley), Burlington white chert,
Louisiana, Mo.

PHYSIOGRAPHIC STUDIES IN THE SAN JUAN DISTRICT
OF COLORADO"

WALLACE W. ATWOOD
The University of Chicago

The studies during the past field season were carried on near the
southern and southwestern margin of the San Juan Mountains
and over the adjoining plateau district. Investigations were
planned for the purpose of working out the complete physiographic
history of the district. The courses of the Pleistocene glaciers were
indicated on the maps and the deposits left by those glaciers
differentiated. In connection with these studies it was possible
to differentiate the moraines of two distinct glacial epochs in each
of the large canyons examined. Beyond the terminal moraines of
each epoch and extending for many miles down stream, terrace
remnants of valley trains were recognized. It was evident from
the position of the younger glacial moraines and younger outwash
valley trains that there had been a notable amount of valley
deepening in hard rocks during the interglacial epoch. This
suggests that the mountain area had been elevated by at least
several hundred feet relative to sea-level during the Pleistocene
period. The glacial features on the south slope of the range did
not differ from glacial features which have been fully described
by various writers who have become familiar with glacial phe-
nomena in the high mountains of the West.

In examining the areas which rose above the upper limit of ice
action on the south slopes of the mountains, certain gravel-strewn
surfaces were found. The gravels were beautifully polished and
of very resistant material. They were composed chiefly of
quartzite, quartz, red jasper, flint, cherts, and greenstones. Much
of the material was less than half an inch in diameter, but some
of the pebbles ranged between one and two inches in their longer

t Published with the permission of the Director of the U.S. Geological Survey.
449

450 WALLACE W. ATWOOD

axes. The surfaces on which these gravels were found were along
the crests between the great mountain canyons and on the tops
of mesa-like hills near the base of the range. If the gravel-strewn
surfaces were extended they would unite and form a plain of gently
rolling topography. That plain would slope away from the core
of the range, show a distinct warping at the base of the range,
and pass off over the upland surfaces of neighboring plateaus.
The nature and distribution of the gravels suggested that they
were remnants of stream deposits in channels which formerly
crossed the present inter-canyon ridges. They appeared to be
the deposits of streams which flowed over low gradients and sug-
gested further, by their distribution and the distribution and
relations of the surfaces on which they were found, a deformed
peneplain. In following this ancient erosion surface southward
_ and southwestward over the plateau district it seemed that
certain of the outlying mesa surfaces would correspond in age to
this peneplain surface, and it was anticipated that on such out-
lying surfaces a mantle or scattering of still finer gravels might be
found. But these mesa surfaces were found to carry a heavy
mantle of bowlder-gravels, in which the larger masses ranged up
to three and four feet in diameter. In these bowlder-gravel de-
posits certain special bowlders could be recognized which came
from outcrops in the mountain areas, and it appeared that they
must have been washed out and deposited as a portion of a great
alluvial fan about the margin of the mountains. These bowlder-
strewn surfaces were followed southward nearly fifty miles from the
base of the range, and at that distance the larger bowlders seen
ranged to at least three feet in diameter. The interpretation of
this bowlder-gravel mantle and its relation to the erosion surfaces
upon which it rests and the erosion surfaces in the mountains which
seem to correspond in age to those underneath the bowlder-gravels
is that at the close of the cycle of erosion during which the pene-
plain as described was developed, there was a general uplift in the
district, which was emphasized in the San Juan dome. The head-
waters of the streams in the uplifted dome were so rejuvenated
that they carried together with sands and gravels many large
bowlders to the base of the range and spread that material out as

PHVSIOGRAPHIC STUDIES IN SAN JUAN DISTRICT 451

alluvial fans over the neighboring plateaus. The streams which
crossed the plateaus were first rejuvenated in their lower courses,
and as rejuvenation worked upstream across the broad plateaus
the growth of the great alluvial fans ceased and their dissection
began. The high-level bowlder-gravels are, therefore,.a deposit
which marks the beginning of a new period of erosion in the moun-
tains and a temporary period of alluviation about the base of the
mountains. The bowlder-gravels are, therefore, not of exactly
the same age, but a little younger than the small peneplain gravels
of the mountain area.

Below the summit elevations in the mountains and in the
neighboring plateaus there are other broad bowlder-capped mesa-
like forms which appear to represent the base to which the streams
worked when the peneplain was first deformed. The bowlder
capping on these mesas is at places as much as thirty feet in thick-
ness. The Florida and Fort Lewis mesas just south of the San.
Juan Mountains are typical of this bowlder-mesa stage in the
dissection of the area. Another uplift associated with the more
or less continuous growth of the mountains deformed the graded
surfaces of the bowlder-mesa stage, again rejuvenated the
streams, and opened another cycle of erosion. The surfaces to
which the streams then worked are represented by broad, open
valleys of late maturity or early old age in the softer rocks, and by
canyons in the harder rocks. This cycle of erosion has been for
convenience referred to as the Oxford stage, for there is an excellent
development of the typical lowlands of this stage near the village
of Oxford, a few miles southeast of Durango. It immediately
preceded the first epoch of glaciation as recorded by the moraines
and outwash deposits found on the south slope of the range. In
the mountain-canyons the bowlder-mesa and Oxford stages are
both represented by rock benches which in some instances carry
stream alluvium.

These studies have opened certain large problems in the rela-
tionship of the mountains to the plateaus, and suggested a close
correlation in the physiographic histories of the two provinces.
Are the high-level bowlder-gravels resting on a true peneplain ?
Of what age is this peneplain? In the area examined during the

452 WALLACE W. ATWOOD

past season it is known to truncate Wasatch beds. Is it not,
however, as late as late Miocene? Does it correspond in age to
the great peneplains of the Grand Canyon district?" Are the
high-level bowlder-gravels bordering the Front Range of the
Rocky Mountains, the Big Horn Mountains,? the Livingston
Range? of the same age as these about the San Juan Mountains ?
Do they rest on peneplain surfaces? Is the Blackfoot Peneplain
of Montana described by Bailey Willis‘ of the same age as the
one observed in this region? Are the Wyoming conglomerates
about the base of the Uinta Mountains, placed in the Pliocene by
the King Survey,’ of the same origin and age as the high-level
bowlder-gravels south of the San Juans? What is the relation-
ship of certain bowlder deposits found near the summit and near
the core of the San Juans, and certain ancient stream gravels which
have been found by Stone, near the summit of the Front Range,
to the bowlder-gravels about the bases of these ranges? Numer-
ous other correlations in the Rocky Mountain areas and in the
Pacific Coast mountains are suggested. Has there been with
each period of mountain growth in the Cordilleran region of
North America a rejuvenation of the streams which affected
the headwaters long before it affected the middle courses of
the rivers, and did these rejuvenated headwaters distribute
the bowlder-gravels in each case on the neighboring pla-
teaus? How far were such deposits carried and how were the
larger bowlders transported? Numerous cases may be cited
where bowlders ten to twelve feet in diameter have traveled at
least twenty-five miles from their sources over surfaces of very
low gradient. If such bowlders can travel twenty-five miles on
gently sloping surfaces, is it not possible for them to travel much
farther than that over low gradients? How are huge bowlders
transported over nearly horizontal surfaces? How far have
climatic changes affected the work of streams in the Rocky Moun-
tain region? Are the reported glacial deposits in southeastern

*H. H. Robinson, Am. Jour. Sci., 4th Series (1907), XXIV, 109-29.

2 Salisbury and Blackwelder, Jour. Geol., II (1903), 220-23.

3 Bailey Willis, Bull. Geol. Soc. Am., XIII (1902), 329-30.

4 Op. cit., 310.

5 Hague and Emmons, Rep. of goth Parallel Survey (1877), II, 64-65, 188-89 ff.

PHYVSIOGRAPHIC STUDIES IN SAN JUAN DISTRICT 453

Utah," in which there are granitic and gneissic bowlders one to
five feet in diameter, the origin of which is at present unknown
unless it be the San Juan Mountains, true glacial deposits or stream
deposits? Could mountain glaciers from the San Juan Range
have reached southwestward one hundred miles from the base
of the range? Is there not some other explanation for the coarse
bowlder deposits reported in that portion of the plateau district ??
Has there been a continuous or periodic growth of the San Juan
dome during late Tertiary and Quaternary times ?3 How are the
great systems of fissures which cut the late Tertiary volcanics
. related in age to the recent deformative movements? Co-operative
work by all who are engaged in field studies in the Rocky Mountains
and plateau provinces should prove of great value in promoting
the solution of these problems.

™D. D. Sterrett, U.S. Geol. Survey, Mineral Resources (1908), Pt. II, 825 (1909).

2.W. M. Davis, Proc. Am. Acad. Aris and Sci., XX XV (1900), 345-73.

3 Cross and Spencer, U.S. Geol. Survey 21st Ann. Rep. (1900), Pt. II, 100.

THE VARIATIONS OF GLACIERS. XVE

HARRY FIELDING REID
Johns Hopkins University

The following is a summary of the Fifteenth Annual Report of
the International Committee on Glaciers.’

REPORT OF GLACIERS FOR 1909

Swiss Alps.—Of the ninety glaciers measured in 1909, only two .
have been advancing for three successive years, the Scex-rouge and
the lower Grindelwald Glacier; the latter has advanced 59 meters
in two years. Nine other glaciers have advanced slightly during
the last year but it is not certain that they are in a stage of advance.
A general retreat is dominant in the Swiss Alps.

Eastern Alps.—Thirty-nine glaciers were measured, and the
retreat is general, although in many cases it is slow. The Lang-
taler Glacier and the Grosselendkees seem to be stationary, and
the Mitterkarferner has made a small advance.‘

Italian Alps.—The retreat, which has been general for some
years, seems to be continuing without change.®

French Alps.—Observations on the snow-fall and the variation
in the length of glaciers have continued, and maps of some glaciers
are being made on a scale of 1 : 10,000. In the Mont Blanc range
the retreat is nearly general, though slight; the Glacier des Bossons
has advanced a little more than one meter. The ends of the
glaciers have in general diminished in thickness with a corre-
sponding diminution in the velocity of flow. In the Tarentaise and
Maurienne the retreat is also general, but feeble. In the Dauphiné
we find that the snow-fall has been distinctly heavier since 1906
with the result that the glaciers on the northern side of the Pelvoux
massif have grown thicker and are beginning to advance; and the

1 The earlier reports appeared in the Journal of Geology, Vols. III-XIX.

2 Zeitschrift fiir Gletscherkunde (1911), V, 177-202.

3 Report of Professor Forel and M. Muret.

4 Report of Professor Briickner. 5 Report of Professor Marinelli.

454

THE VARIATIONS OF GLACIERS 455

whole appearance of the reservoirs indicates that the advance in
this region will become general. In the southern part of the same
massif, although the increase in the snow-fall is also marked, the
retreat of the glaciers continues. In the Pyrenees the snow-fall has
been heavy since 1906 and the small glaciers show a marked
tendency to increase in size.’

Swedish Alps.—A number of glaciers have been measured and
the changes resulting during a variable number of years up to 1909
indicate a slight increase in general, though a few of the glaciers
are apparently stationary and one or two slightly retreating? _

Norwegian Alps.—The difference in the behavior of the glaciers
of Jotunheim, in the interior of Norway, and those of Folgefon
and Jostedalsbraé, near the coast, which was commented on in
the last report, continues. The glaciers near the coast are generally
advancing, whereas those in the interior are generally retreating.

Russia.—The greater part of the glaciers observed in the Cau-
casus between 1899 and 1907 have retreated. A few have remained
stationary and only two have made an advance. A number of
glaciers in the Altai and Muss-tau mountains, in Siberia, have been
visited but no careful measurements made.*

REPORT ON THE GLACIERS IN THE UNITED STATES FOR IgIo§

There are a number of small glaciers in Colorado which, on the
whole, show a tendency to become smaller, but their variations
from year to year are extremely slight.°

The Hallett Glacier shows no measurable change since 1909
(Mills).

The Carbon Glacier on the northern side of Mt. Rainier is in
marked recession (Matthes).

The United States Geological Survey has been continuing its

* Report of M. Rabot. 3 Report of M. Oyen.

2 Report of Professor Hamburg. 4 Report of Colonel Schokalsky.

5 A synopsis of this report will appear in the Sixteenth Annual Report of the Inter-
national Committee. The report on the glaciers of the United States for the year
1909 was given in this Journal (XIX, 83-809).

6 All available information regarding these glaciers has been collected by Judge
Junius Henderson, ‘‘Extinct and Existing Glaciers of Colorado,” University of Colo-
rado Studies (1910), VIII, 33-76.

456 HARRY FIELDING REID

explorations and surveys of Alaska, and several glacier regions have
been mapped. A number of glaciers north of Juneau are in rapid
recession. The glaciers in the neighborhood and north of the head-
waters of the Copper River (in the neighborhood of latitude 633°
N and longitude 145° W) seem to be retreating slowly (Brooks).

Fresh moraine, extending for nearly two miles at the end of
Nabesna Glacier, shows that it is retreating rather rapidly. The
Chisana Glacier, 15 miles to the east, has a very clean end; a com-
parison of photographs taken in 1899 and 1908 shows surprisingly
little change in the aspect of the glacier, though at one place a
slight recession has taken place. Frederika Glacier, entering White
River valley from the north, when seen by Dr. C. W. Hayes in 1891
ended ‘‘in a nearly vertical ice cliff... . about 250 feet high.
At the foot of the cliff there is a small accumulation of gravel and
ice fragments apparently being pushed along by the advancing
mass.”* In 1909 Mr. Stephen R. Capps says “its surface is
remarkably smooth and slopes down evenly to a thin edge in
front.” The Frederika Glacier has evidently changed from an
advancing to a retreating glacier in the interval. Exactly opposite
Frederika Glacier another glacier, in retreat in 1891, is now
advancing.”

Such spasmodic cases are probably produced by sudden acces-
sion of material due to avalanches or land slides, rather than to
simple variations in snow-fall or temperature.

The Ruth Glacier, rising on Mt. McKinley and extending many
miles to the east, is slowly diminishing in size (Rusk).

Professor U. S. Grant and Mr. D. F. Higgins have published a
general map of Prince William Sound, showing the location of all
the glaciers, on a scale of 4 inches to the miles They have also
published descriptions, pictures, and detailed maps of the ends of
several of these glaciers.4 The last observations were made in

« “Expedition through the Yukon District,” Nat. Geog. Mag. (1892), IV, 153.

2 Glaciation on the North Side of the Wrangell Mountains, Alaska,” Jour.
Geol. (1910), XVIII, 56.

3 “Reconnaissance of the Geology and Mineral Resources of Prince William
Sound, Alaska,” U.S. Geological Survey, Bulletin No. 443, Washington, 1910.

4 “Glaciers of Prince William Sound and the Southern Part of the Kenai Peninsula,
Alaska,”’ Bull. Amer. Geog. Soc. (1910), XLII, 721-33.

THE VARIATIONS OF GLACIERS 457

the summer of 1909 and we note that the Shoup Glacier was
practically stationary and was fully as large then as it had been
for several decades. The Columbia Glacier was found, at its
eastern edge, about 500 feet in advance of its position of 1899, and
this advance seems to have taken place principally since the
summer of 1908. Professor Grant found indications that the
glacier was well in advance some fifty years ago and before that
date was considerably smaller. The Meares Glacier seems to be
a little in advance of its position of 1905, and the general condition
of the vegetation in the immediate neighborhood indicated that
the glacier in 1909 was probably as far forward as it has been
during the last one hundred years or more.

Professor Lawrence Martin conducted another expedition for
the National Geographic Society in 1910 to study the Alaskan
glaciers. He sends me the following notes:

Fairweather Range.—La Perouse Glacier advanced approximately a quarter
mile between September 4, 1909, and June 10, 1910, and was destroying
forest on the latter date, as it had previously done in September, 1895.

Yakutat Bay.—Nunatak Glacier advanced 700 to 1,000 feet between
July 6, 1909, and June 17, roro0, after retreating steadily at least 24 miles from
1890 to 1909. Hubbard Glacier did not continue to advance as rapidly as
seemed possibly would be the case in 1909, parts of the front advancing 600
feet between 1909 and rgto while other parts retreated 500 to 1,000 feet. In
1910 Lucia Glacier had probably nearly ceased the great advance which was
in progress in July, 1909. Nunatak Glacier is the ninth ice tongue in the
Yakutat Bay region to advance since 1899, following a long period of contin-
uous retreat or stagnation. In each case listed below the advance is thought
to be the result of great accessions of snow and ice by avalanches during the
earthquakes of September, 1899.

Glacier Date of Advance Length of Glacier
Galiamomnncncynaren cnn toca, After 1895 and before 1905 2o0r 3 miles
Unnamed Glacier...:...... IQOI 3 or 4 miles
Elaenke rrr ae 1905-6 6 or 7 miles
INET OVA Ayatsen easy fone ue aie fy 1905-6 8 miles
Nariegatedia waeyaccaccens). 1905-6 Io miles
IMR VAM ER Meee asides eee le es 1905-6 to miles}
lid demvgatse eee eee eas nt 1g06 or 1907 16 or 17 miles
NSW Ciaanes Fc eee tami nes oie. cie 1909 17 or 18 miles
INjumattalke ee acwemutusas: arorduevacacte IgIo 20 miles

* Between Haenke and Hubbard glaciers.
{ Excluding expanded lobe in Malaspina.

458 HARRY FIELDING REID

Prince William Sound.—Columbia Glacier advanced 600 feet between
August 24, 1909, and July 4, 1910, and at least 132 feet more between the latter
date and September 5, 1910. In College Fiord the Harvard, Yale, Radcliffe,
Smith, Bryn Mawr, Vassar, Wellesley, and Barnard glaciers were advancing
much more actively in toro than in 1909, and were destroying forest at their
borders, as were the Meares Glacier in Unakwik Inlet, the Harriman, Baker,
Roaring, and Cataract glaciers in Harriman Fiord, and the Blackstone Gla-
cier in Blackstone Bay. Harvard glacier had advanced 100 to 150 feet,
Yale 750 feet, and Harriman 300 feet between 1899 and ro10. Barry and
Surprise glaciers in Harriman Fiord retreated 23 and 14 miles respectively
from 1899 to 1910, different parts of the Barry retreating 500 to 1,600 feet
of this distance between 1909 and ro10. Valdez and Shoup glaciers in eastern
Prince William Sound and Nellie Juan Glacier in Port Nellie Juan remained
unchanged from 1908 to 1910, as did Chenega, Princeton, and Tiger glaciers
in Icy Bay, where there was a six or seven mile retreat between 1787 and 1908,
most of it later than 1898. Portage Glacier in Passage Canal had a great
advance between 1794 and 1880, filling a pass from Prince William Sound to
Cook Inlet to a height of over 1,000 feet, where there was previously a low
canoe portage and no glacier.

Copper River.—Miles Glacier retreated about 1,700 feet from 1900 to 1906
and readvanced 1,800 feet from 1906 to 1910. Grinnell Glacier advanced
slightly between 1909 and 1or1o. Different parts of the front of Childs Gla-
cier advanced 920 to 1,225 feet between 1909 and June, roro, in midglacier,
where the front is undercut by Copper River. On the north bank of the river
where the margin of the glacier ends on the land and was stagnant in 1909,
it advanced 1,500 to 1,600 feet up to June 10, 1910, and 204 feet more up to
October s, 1910. The glacier front developed lobes so that some parts advanced
faster than others. The rates per day through the summer of 1910 were as
follows:

; ADVANCE IN METERS | RATE PER Day IN FEET
DaTES Days
Fastest Average Fastest Average
une! to tom ius 2 Oesaeaceer ect 49 124 116 Ds Does)
allio ORE OPAIOR Orme ae eaiater 8 26 23 3.25 2.87
INGLES AMO VaGOKeas AIC g's g cae S 5 41 8 See 1.60
Age Dt COPA RET einen cane 6 27 4 4.5 0.66
Aug 17, tov AUS 20m cries 12 42 ae) Boi 1.58
INiNer BAOV AHO) SONS Cla sono casas 21 37 27 1.76 1.28
Sept. 19 to Oct: 55... .: rata Hee 17 118} rE} 0.7 0.44

In midglacier there was a relative retreat of the advancing ice front from
June to September, while the north border continued to advance strongly,
as shown above. ‘This retreat was due to undercuttings during the summer

THE VARIATIONS OF GLACIERS 459

rise of the river and was followed by a strong advance in late September and
early October when the level of the river fell and its undercutting power was
weakened. This oscillation is shown in the accompanying table.

Dates Variation of Glacier Stage of River

1909 to June Io, t9to.......| Advance, 920—-1,225 ft. Fall, 14 ft., May 6 to

June to
iunesToktoy Auge iE). sass: Retreat, 450 ft. Rise, 6 ft.
PAN OA mToTe COMA Gee Titres oars aay! Retreat, 65 ft. Level, about stationary
ANUS: 057 (WO) === 5 Hla doe aac Retreat continued....... Rises tag ite

LOO CE Se une et pies Advance, 390 ft., plus
unknown retreat above | Fall, 9 ft.

As this advance of Childs Glacier seriously threatened a $1,400,000 steel
railway bridge which in October, to10, was only 1,575 feet from the north
margin of the glacier, the behavior of Childs Glacier during the winter of 1910-
r1, when Copper River is low and weak, will be of much interest. The diminu-
tion of movement on the north bank suggests, however, that the advance
is practically over. The advance of Grinnell Glacier is also of interest, for
this ice tongue occupies a strategic position with reference to the railway,
which traverses its stagnant outer portion. In this portion, however, there
was no disturbance in 1gio, the advance affecting another part of the glacier.
The Allen Glacier, whose stagnant outer portion is traversed for 54 miles
by this railway, remained unchanged from 1909 to 1910.

It appears, therefore, that the glaciers about Prince William
Sound give some indication of a general, but not very large, advance.

CoRRECTION.—In the Report on the Glaciers of the United States
for 1908 (Journal of Geology, XVII, 671), the name ‘‘Matamaka
Glacier”? should have been “ Matanuska Glacier.”

The regular meeting of the International Committee on Glaciers
took place in Stockholm on the 2oth of August, tgto, in connection
with the Eleventh International Geological Congress.’ The retir-
ing president, Professor Edouard Briickner, presented the report
of the Committee to the Congress.

He called attention to the origin of the Committee, which was
first appointed by the Sixth International Geological Congress in
1894, and has been collecting information regarding the variations
of glaciers ever since; and emphasized the importance of the work

« “Ta Commission internationale des Glaciers au Congrés géologique international,
Stockholm, aott, 1910.” Zeitschrift fiir Gletscherkunde (1911), V, pp. 161-76.

460 HARRY FIELDING REID

of Professor Finsterwalder, who, as retiring president in 1903, laid
down the fundamentals of a mathematical theory of glacier varia-
tions. He then reviewed the information collected regarding the
variations of glaciers. In the Alps the retreat of the glaciers con-
tinues steadily, although a few glaciers of the Oetztal and some
others have made small temporary advances. The retreat has
lasted for several decades. A graphic representation of the varia-
tions of 26 glaciers in the Swiss Alps, including the Mont Blanc
group, shows that, for the greater number of them, the retreat
has lasted since the beginning of the nineteenth century, and that
the advance which occurred about 1850 was but an episode in the
general retreat. Since that time the retreat has been still more
marked. In the Scandinavian Alps the variations have been some-
what different; in this region an advance occurred in the beginning
of the twentieth century. It began in the Jostedalsbra and the
Folgefon and progressed toward the north; but the advance was
confined to the coast region and the glaciers in the mountains
of central Scandinavia did not participate in it. This advance
must also be looked upon as an unimportant event in the general
retreat. The glaciers of the Caucasus, of the Tyan-Shan, the Altai,
the Highlands of Pamir, and the Himalaya are in retreat, though
here also special cases of advance have been noted. Among the
glaciers of the United States and Canada the retreat is general
and this is true to a still more marked extent in Alaska. Between
1892 and 1907, the retreat of the glaciers has increased the area of
Glacier Bay by 19 square miles. Of great interest are the sudden
remarkable advances of the glaciers of Yakutat Bay, which Pro-
fessor R. S. Tarr has described and imputed to the great increase
in snow-supply due to avalanches incited by the earthquakes of
1899. Professor Hauthal has described the rapid advance of the
Bismarck Glacier, in South America, since the end of the last century.

Professor Kilian described the variations of glaciers in France.
_ The importance of the water from glacial streams has led the Min-
ister of Agriculture to give material aid to the observations of
glaciers.

Professor Dr. F. W. Svenonius spoke of the difficulty of making

THE VARIATIONS OF GLACIERS 461

observations among the Swedish glaciers on account of their distance
and inaccessibility, but nevertheless the Swedish Geological Sur-
vey has published a collection of six essays by the leading Swedish
glacialists which give an excellent account of what is known of
these glaciers."

t Dr. Axel Hamberg has been elected an ordinary member of the Committee to
represent Sweden, succeeding Dr. F. W. Svenonius, who has retired and been elected
a corresponding member. Professor R. S. Tarr has also been elected a corresponding
member. Two corresponding members, Mr. W.S. Vaux, Jr., and Professor E. Hagen-
bach-Bischoff, have died since the 1906 meeting of the Committee. The following
officers were elected to serve until the next meeting of the International Congress of
Geologists: Honorary President, Prince Roland Bonaparte of Paris; Active Presi-
dent, M. Charles Rabot of Paris; Secretary, M. Ernest Muret of Lausanne.

PETROLOGICAL ABSTERACES! AND TR EVILYES

EDITED BY ALBERT JOHANNSEN

ARSCHINOW, WLADiImIR. ‘‘Ueber die Verwendung einer Glashalb-
kugel zu quantitativen optischen Untersuchungen am Polari-
sationsmikroskope,”’ Zeitschr. Kryst., XLVIII (1910), 225-29.
Fig. i.

A simple apparatus for making quantitative measurements by
tilting a thin section under the microscope. The author claims to be
able to make measurements with as great a degree of accuracy as may
be made with Fedorow’s or Klein’s Universaltisch.

The instrument consists of a glass hemisphere, 50-60 mm. in diameter,
which is centered upon the stage of the microscope and rotated by hand.
The section is fastened to the flat side of the hemisphere with cedar oil
or glycerin, and with the cover-glass down. The determination of
planes of extinction and so on are made as with the Fedorow Univer-
saltisch, and the angle of rotation is measured by means of two grad-
uated metal strips, attached 90° apart, to a movable ring around the
equator of the glass hemisphere, and themselves capable of being moved
on pivots. By raising the tube of the microscope above these rings, the
angles at which they cross may be read, and this determines the amount
of rotation of the glass hemisphere. For certain measurements a small
glass hemisphere, 8-15 mm. in diameter, is attached to the upper sur-
face of the slide.

ALBERT JOHANNSEN

Bastin, Epson S. ‘‘Geology of the Pegmatites and Associated
Rocks of Maine,” Bull. U.S. Geol. Survey No. 445, Washington,
TOM. | Ro s52, platoiss. co eimape Te

In this bulletin on the pegmatites of Maine, Doctor Bastin has
given not only local descriptions but has made an important contribu-
tion to the general literature of the pegmatites as well. The work is
divided, practically, into three parts: a general discussion of pegmatites

462

PETROLOGICAL ABSTRACTS AND REVIEWS 463

and in particular those of Maine, local descriptions by counties, and
descriptions of the economically important minerals.

Granite-pegmatites are defined here as differing but little from the
granites of the state in mineral composition, but are characterized, not
necessarily by coarse, but by extreme irregularity of grain. They
occur in dikes or sill-like masses, generally of sheet-like form and some-
times of considerable size. The contact with the country rock is gen-
erally sharp, indicating very little assimilation by the pegmatite even
where it is of batholithic dimensions. Contact metamorphism around
the pegmatites is no greater than that near granite contacts, and indi-
cates, according to the writer, that the amount of mineralizers present
was but little greater than in the latter rocks; less than ten times as
great, probably. Genetically the pegmatites are related to the asso-
ciated granites and are probably contemporaneous with them. Where
particularly abundant, they form, apparently, the roofs above granite
batholiths. An examination of the quartz grains indicates, in the
coarser varieties, that the crystallization began slightly above 575° C.
and ended at a lower pom EUL Gs The finer-grained varieties may
have crystallized entirely above 575°.

Among the minerals of economic importance found in the Maine
pegmatites are the feldspars, orthoclase and microcline rose and smoky
quartz, amethyst, muscovite, tourmaline, beryl of various colors, and
topaz. The occurrences, compositions, properties, and uses of these

minerals are discussed.
ALBERT JOHANNSEN

CovuyatT, J. ‘‘Les roches sodiques du désert arabique,” Compies
Rendus de V Académie des Sciences, CLI (1910), 1138-41.

In a region east of the Nile, near longitude 34° 18’ E., latitude 24°
40’ N., there are dikes and stocks of nepheline syenite with much varia-
tion in texture, also tinguaite and sélvsbergite. Four analyses of the
syenite show SiO, 60.1 to 56.5 per cent; Na.O g.0 to 10.6 per cent;
KOA. se toes-2per cent: Fe,O,;, FeO 3.2 to 6.1 per cent; very low
MgO and CaO. In the quantitative classification the rocks are mias-
koses and laurdaloses.

The syenites are related to volcanic eruptives of Cretaceous age
and posterior to a series of trachytes, andesites, and basalts.

F.-C. CALKINS

464 PETROLOGICAL ABSTRACTS AND REVIEWS

Duparc, L., AND Pampuit, G. “Sur Vissite, une nouvelle roche
filonienne dans la dunite,’’ Comptes Rendus de l Académie des
Sciences, CLI (1910), 1136-38.

The rocks described form dikes in massive dunites of the platinum
deposits in the basin of the river Iss. They consist mainly of horn-
blende, with subordinate pyroxene, labradorite in some cases, magnetite,
and apatite. Five. analyses are given. SiO, ranges approximately
from 33 to 47 per cent; Fe.O, from 3 to 9 per cent; FeO from 14 to 9
per cent; CaO from 16 to 11 per cent; MgO from to to 7 per cent;
total alkalies 2 to 3 per cent. In the quantitative classification, the
rocks fall in auvergnose and three unnamed subrangs.

F. C. CALKINS

Duparc, L., AND WuNDER, M. “Sur les Serpentines du Krebet-
Salatim (Oural du Nord),” Comptes Rendus de l’ Académie

des Sciences, CLII (1911), 883-85.
Describes dunites and harzburgites more or less completely altered
to antigorite and bastite. Five analyses. of these rocks and one of the

inclosed calcareous hornfels are given.
F. C. CALKINS

GRANDJEAN, F. ‘‘Sur un mesure du laminage des sédiments
(calcaires et schistes) par celui de leurs cristaux clastiques
de tourmaline,’ Comptes Rendus de l’ Académie des Sciences,
CLI (1910), 907-9.

The author finds tourmaline an unfailing constituent of shales and
limestones. The crystals of this mineral in deformed rocks show a
middle portion normal in color and apparently undeformed, and ragged
terminal portions of paler hue. The terminal zones are considered due
to elongation of the tourmaline, and their average length (about 30
measurements is ordinarily sufficient) gives a co-efficient of deforma-

tion for the rock.
F. C. CALKINS

GRoTH-JACKSON. The Optical Properties of Crystals. New York:
John Wiley & Sons, 1910. Pp. xiv+309, figs. 121, colored
plates 2.

In spite of a number of good books on optical crystallography which
have appeared within the past few years, no work has quite taken the

PETROLOGICAL ABSTRACTS AND REVIEWS 465

place of Groth’s classical Physikalische Krystallographie, and it is with
great pleasure that this translation of certain parts is welcomed. The
only criticism that can be made is that Professor Jackson did not trans-
late the entire work.

The translation, in general, follows the form of the original and
includes all of the ‘Optical Properties” in Part I, with additions, here
and there, from the parts in the original devoted to systematic descrip-
tions of crystals and methods of crystal investigation. The translation
seems to be good, although, in places, the sentences, closely following
the German, are rather long. A slight error is introduced, on p. 15,
where the number of vibrations per second of red and violet light are
spoken of, by the translation of the German billion (10%) as billion
(10°).

The book is well gotten up, and the line drawings, apparently from

wax plates, are sharp and clear.
ALBERT JOHANNSEN

Howe, J. ALLEN. The Geology of Building Stones. New York:
Longmans, Green & Co.; London: Edward Arnold, 1g9ro.
12mo, pp. vilit+-455, pl. 8, maps 7, figs. 31.

This work, the fourth of Arnold’s Geological Series, under the
general editorship of Dr. J. E. Marr, apparently is intended primarily
for architects. It treats of the rock-forming minerals and the rocks in
non-technical language and gives the principal properties of each.
The decay of building stone is discussed, and methods of testing are
described. The author says, ‘There is no help: sooner or later, in the
course of practice, the architect or engineer will have the need of some
geological knowledge forced upon him.” If the little knowledge is not
a dangerous thing, this book may serve a useful purpose.

ALBERT JOHANNSEN

Lacroix, A. “Le cortége filonien des péridotites de la Nouvelle
Calédonie,’ Comptes Rendus de VAcadémie des Sciences,
CLIT (1911), 816-22.

The peridotites of Nouvelle Calédonie are cut by narrow dikes form-
ing a gabbroic and a dioritic series. In both, gradations can be traced
between a leucocratic extreme (anorthosite) and a melanocratic extreme,
(pyroxenite or hornblendite). Nine analyses are given which prove
that six of the rocks fall into previously unnamed subdivisions of the

466 PETROLOGICAL ABSTRACTS AND REVIEWS

quantitative classification. These are: Ouenose (III. 5. 5. 4-5);
Caledonose (I. 5. 5. 4=5);) Dhiose” GV. a[2)5 tl2]4* 2) Naketose
(QV. 2l3ky aleier2)5 shoghosea(hiny a aie4— 5)

In the gabbroic series, Si0,, Al,O;, and CaO increase together, while
FeO and MgO decrease. Because of the basicity of the feldspars the
most feldspathic phase is the poorest in SiO,._ In the dioritic series, the
proportion of lime is nearly constant, silica varies irregularly, Al,O; and
alkalies increase with the feldspar content.

There are also dikes composed almost wholly of magnesiochromite;
these locally contain chrome-bearing diopside and bronzite, and are

associated with anorthosites.
F. C. CALKINS

Leiss, C. ‘Neues Mikroskop Modell VIb fir krystallogra-
phische und petrographische Studien,’ Zeztschr. Kryst.,

XE VAN (toro) 24 42s higeate
A large microscope similar in construction to the Hirschwald micro-
scope (Fuess VIa). It differs, however, in having an Abbe condenser
and Ahrens polarizer, and a large, flat micrometer stage. Like the
VIa microscope, the upper and lower nicols can be rotated simultaneously.
This does away with the cap nicol and permits the use of a large tube,

iving an extra large field.
§ 5 g
ALBERT JOHANNSEN

SKEATS, ERNEST W. ‘‘The Volcanic Rocks of Victoria,’ Austra-
lian Association for the Advancement of Science, 1909, 173-235.
Pl. 4, numerous analyses.

This paper was read as the Presidential Address, Section C, of the
Australian Association for the Advancement of Science. It contains
a summary of the present knowledge of the Victorian volcanic rocks
and has appended a bibliography of 268 items, dealing wholly, or in part,
with these rocks. The geographical distribution is shown on a map and
the geological range was determined to be from Basal Ordovician ( ?)
to recent. Petrographically the rocks are rhyolites, dacites, basalts,
quartz porphyries, granite porphyries, diabases, serpentines, quartz
keratophyres, melaphyres, sdlvsbergites, limburgites, and the new
rocks anorthoclase trachyte, anorthoclase-olivine trachyte, olivine-
anorthoclase basalt, olivine-anorthoclase andesite, and macedonite.
Petrographical descriptions, not 'as complete as might be desired, espe-

PETROLOGICAL ABSTRACTS AND REVIEWS 467

cially those dealing with new types, are given, and the geographical and
geological relations are shown. The new rock terms proposed are:

Anorthoclase trachyte—This type was previously described by
Professor Gregory as trachyphonolite. As described by Skeats, in
a corrected copy of his paper, it is ‘“‘a dark-greenish rock. Large
phenocrysts of anorthoclase are numerous. The ground mass has
sometimes a fluidal arrangement of laths of anorthoclase, in other cases
the crystals are stouter and the structure orthophyric. Small crystals
of aegirine are scattered through the rock, a little green glass, a few sec-
tions of nosean, ilmenite, and occasionally apatite are also present.’’
From the description it does not appear that any other feldspar occurs,
although the statement, in another place, that “anorthoclase is the
dominant felspar,”’ suggests that another is present.

Anorthoclase-olivine trachyte-—Spoken of as “more basic than the
rock just described.”’ It resembles the former rock but contains, in
addition, more or less olivine.

Olivine-anorthoclase basalt—‘‘A still less acid type... . . It

differs mainly from the last type in the greater abundance of olivine
and less frequent anorthoclase.”” In the opinion of the reviewer this
description would hardly justify the use of the term basalt.
_ Macedonite is a non-porphyritic, basaltic-looking rock and in the
annotated copy is said to “consist largely of minute felspars, a colour-
less to green interstitial mineral, either glass or chlorite, serpentine or
chlorite pseudomorphs after olivine, some light-brown biotite and
purplish, fibrous apatite prisms. Octahedra of perofskite occur, some
of which are opaque, others of a dark grayish-green colour. The exact
relations of this rock are difficult to determine. Chemically it is in
some respects intermediate between the tephrites and the orthoclase
basalts, but mineralogically it is quite distinct. Its nearest relations
are with the mugearites, from which it differs in the ratio of soda to
potash and in the small amount of olivine present.” The writer does
not say what kind of feldspar is present, but if the analysis is computed
in the Quantitative System of C.I.P.W., the norm shows orthoclase,
20.02 per cent, albite, 29.87 per cent, and anorthite, 18.63 per cent.
As computed by the reviewer the rock is a Shoshonose.

Olivine-anorthoclase andesite—This is a porphyritic, subsiliceous
andesite. It contains lath-shaped plagioclase and granular or ophitic
augite, magnetite, and olivine as its normal constituents. Corroded
phenocrysts of anorthoclase occur and connect this type with the alkali
rocks.

468 PETROLOGICAL ABSTRACTS AND REVIEWS

While exact and detailed descriptions may seem tedious in an address,
it would be desirable in printed descriptions of new types of rocks
that they be made as complete as possible and that the relative amounts
of the different constituents be stated. For such rocks, clear-cut
definitions should be given.

The paper is a well-written summary of what is known of the vol-
canic rocks of Victoria, and one is always thankful for contributions
containing careful analyses and complete bibliographies.

ALBERT JOHANNSEN

Watson, THomas L. ‘Intermediate (Quartz Monzonitic) Char-
acter of the Central and Southern Appalachian Granites,”’
Bull. Phil. Soc., Univ. Va., I (1910), 1-39.

By comparing the analyses of granites from different parts of the
Appalachian region, the author finds that they are, in general, of mon-
zonitic character, the soda being molecularly equal to or greater than
potash. Comparing the western granites with the Appalachian rocks,
he finds that “the eastern type shows stronger granite affinities and the
western type stronger quartz diorite affinities.”’ In general the granites
of the eastern region are of similar composition, containing acid oligo-
clase and some albite in addition to potash feldspar; the ratio aver-
aging 1.88 to 1. All of the granites, from Alabama to New England,
as well as the subsilicic gabbros, diabases, pyroxenites, and peridotites,
“have been derived from a common parent body of magma intruded,
in most cases, at different times,” says the writer. The age of the
massive granite is stated to be early or later Paleozoic, while the gran-
ite-gneisses (gneissoid-granites) are pre-Cambrian.

Numerous analyses, all of them partial, are given.

ALBERT JOHANNSEN

REVIEWS

The Coming of Evolution: the Story of a Great Revolution. By
JoHn W. Jupp. London and Edinburgh: The Cambridge
University Press, 1910. Pp. 171.

The numerous addresses which were delivered in various parts of
the world in connection with the recent Darwin Centenary seem to
have had for their common burden the revivification of all science by
the revolution which Darwin introduced in the biological field. Seldom
has it been pointed out, and never before in so convincing a manner,
that the acceptance of evolution for the organic world was a direct out-
growth of its demonstration in the field of geological science. It was
the publication by Sir Charles Lyell in 1830-33 of his Principles of
Geology, giving currency to continuity or uniformitarianism in the realm
of inorganic nature, that laid the foundations of modern geology and
paved the way for modern biology as well. Darwin was first a geologist,
and his great debt to Lyell he was ever ready to acknowledge. Says
Professor Judd: “Were I to assert that if the Principles of Geology had
not been written, we should never have had the Origin of Species, I
think I should not be going too far; at all events, I can safely assert,
from several conversations I had with Darwin, that he would have
most unhesitatingly agreed in that opinion.”

Huxley has given his verdict that ‘consistent uniformitarianism
postulates evolution as much in the organic as in the inorganic world.”
In dedicating the second edition of his favorite work, the Narrative of
the Voyage of the Beagle, Darwin wrote: ‘‘To Charles Lyell, Esq., F.R.S.,
this second edition is dedicated with grateful pleasure, as an acknowl-
edgment that the chief part of whatever scientific merit this journal
and the other works of the author may possess, has been derived from
studying the well-known admirable Principles of Geology.’ ‘To Leonard
Horner he wrote: “I always feel as if my books came half out of Lyell’s
brain.”’ In the Origin of Species Darwin refers to “Lyell’s grand work
on the Principles of Geology, which the future historian will recognize
as having produced a revolution in Natural Science.”

The Coming of Evolution, first in the geological and later in the
biological field, has fortunately now been told by a veteran geologist

469

470 REVIEWS

and one who enjoyed the friendship of all the great leaders in the move-
ment—Huxley, Hooker, Scrope, Wallace, Lyell, and Darwin. Of those
who were on terms of affectionate intimacy with both Charles Lyell
and Charles Darwin, Professor Judd is perhaps the unique survivor.
It is this intimate personal relationship to the chief actors in the great
drama, combined with a peculiarly simple and graceful style of writing,
which makes the fascination of this little book. At every turn of the
page the reader is surprised by the reference to some remark of Lyell,
Darwin, or Huxley, which sheds a flood of light upon the psychology of
the whole movement.

The great success of the Principles of Geology seems in some
measure to have been due to Lyell’s study of the causes of failure of
the Theory of the Earth by the illustrious Hutton, whose death occurred
the year Lyell was born. On the basis of his extended observations,
Hutton as early as 1785 wrote the oft-quoted, “I can see no evidence
of a beginning, and no prospect of an end,” a blunt statement which
antagonized the church, then especially active in hunting heresy.
Furthermore, his work was written in a heavy and cumbrous style.
Profiting by this example, Lyell schooled himself in graceful, accurate,
and forceful expression, and at some pains and with favoring fortune
was able to avoid a clash with the established church. In no small
measure this was due to an extremely favorable notice of his Prin-
ciples in the Quarterly Review, then the champion of orthodoxy. With
the geologists of the official Geological Survey, Lyell was less fortunate,
and in spite of the general popularity of his epoch-making ideas, they
were bitterly fought by the official class of geologists and only slowly
won support in this field. Professor Judd’s fascinating story of the
coming of evolution should find a wide circle of readers, especially among
students of natural science.

Wr.

North American Index Fossils: Invertebrates. By AMADEUS W.
GRABAU AND HERVEY WOODBURN SHIMER. Vols. I and II.
New York: A. G. Seiler & Co., 1909 and 1910.

With the rapid accumulation of special literature in the field of
systematic paleontology, and the growing inaccessibility of many of
the older works except to those having access to large libraries, it is
ever becoming more and more difficult for the non-specialist to identify
his species of fossils. At the same time, with the growing refinements
in stratigraphy, it is ever becoming more important to the stratigraphic

REVIEWS 471

geologist to give close attention to the fossil faunas present in his rock
formations, and to have accurate identifications of his fossils. It is,
therefore, a pleasure to notice the appearance of such a work as North
American Index Fossils by Grabau and Shimer.

In the two volumes of 853 and gog pages respectively which: com-
prise this work, approximately 1,500 genera and 4,000 species are
defined, a large portion of the species being accompanied by illustrations
incorporated in the text, the figures being copied from various sources
for which credit is always given. The species selected for definition
have been chosen to include, first, those most characteristic of impor-
tant stratigraphic divisions, i.e., those of wide geographic and limited
stratigraphic range; secondly, those having a wide geographic distri-
bution even though their stratigraphic range is also great, i.e., the very
common American species; and thirdly, forms which it is important
that students of structural and anatomical paleontology should under-
stand. The species are arranged chronologically under their respective
genera, the genera being arranged systematically under their proper
families, orders, classes, and phyla. Brief discussions of the structural
features of each phylum and class are included, but except in the case
of the Arthropoda, no definitions of subclasses or orders are given.
Under each class is given a brief bibliography of the more important
literature, which will be of use to such as wish to carry their studies
beyond the limits of the work. A decided innovation is the inclusion
of extensive analytical keys to the genera under each of the classes.
These keys are probably the most elaborate ever attempted for fossil
invertebrates, and will doubtless be of much value to those using the
books, although it must be kept in mind always that such keys can
never be of so great utility in the classification of fossils, which are fre-
quently if not usually represented by more or less incomplete speci-
mens, as in the classification of living organisms.

The closing pages of the second volume are given up to a series of
appendices, as follows: A, Summary of North American Stratigraphy,
Tables of Geological Formations (50 pages); B, Faunal Summary,
Tables Showing Distribution of Species Described (50 pages); C,
General Bibliography of North American Invertebrate Index Fossils
and Fossil Faunas (1832-1909) (89 pages). In this bibliography the
titles are arranged in accordance with the geological systems, those for
each system being grouped geographically; D, Hints for Collecting and
Preparing Fossil Invertebrates (16 pages); E, Glossary (36 pages) and
General Index.

472 REVIEWS

These volumes have been prepared primarily for the non-specialist,
more especially for workers in stratigraphic geology who have not
received special training in paleontology. For such workers, as well as
for geological students in colleges and universities, and for amateur
paleontologists and collectors of fossils, the volumes will prove to be of

great value.
S. W.

Olenellus and Other Genera of the Mesonacidae. By CHARLES D.
WALcoTT, Smithsonian Miscellaneous Collections, LV, No. 6.

In his memoir on the Olenellus fauna, published in the Tenth Annual
Report of the United States Geological Survey, in 1891, Walcott recog-
nized seven American and three foreign species of Olenellus, included in
three subgeneric groups, Olenellus proper, Mesonacis, and Holmia. ‘The
present contribution represents the advance of knowledge concerning
this highly interesting group of Cambrian trilobites since the appearance
of the earlier memoir. Thirty-four species, including two varieties, are
now recognized, besides two undetermined ones, thirty-six in all, arranged
in ten groups which are given full generic rank, the entire group of forms
being elevated to a family under the name Mesonacidae. ‘Twenty-four
of these forms are American and twelve foreign, the foreign representa-
tives being known only from northwestern Europe.

With the restriction of the genus Olenellus to include only one group
of these species, it comes about that this genus is no longer characteristic
of the entire Lower Cambrian, as has commonly been assumed since the
publication of the earlier memoir, but occurs only in the uppermost
division of the series. In the present paper the Lower Cambrian is
divided into four faunal zones, designated, beginning with the oldest,
(1) Nevadia zone, (2) Elliptocephala zone, (3) Callavia zone, (4) Olenellus
zone, each named from the leading Mesonacid genus present in the fauna.
Aside from these four index genera the following are recognized: Meson-
acis Walcott, Holmia Matthew, Wanneria n. gen., Paedeumias n. gen.,
Peachella n. gen., and Olenelloides Peach.

In their genetic relations the genera discussed are assumed to diverge
along two lines from the primitive Nevadia. The one line includes
Callavia, Holmia, and Wanneria in order, the last of which is supposed
to give origin to Paradoxides of the Middle Cambrian. The second line
of descent springing from Nevadia includes Mesonacis, Elliptocephala,
Paedeumias, and Olenellus in serial order, the last of these genera giving
origin on the one hand to Peachella and on the other hand to Olenelloides.

REVIEWS A473,

Some question may be raised, perhaps, as to the legitimacy of the
assumption of such a phylogenetic origin of Paradoxides. The most
diagnostic character of the entire family Mesonacidae is the absence of a
facial suture, although well-developed compound eyes are present.
Elsewhere among the trilobites, where the free and fixed cheeks have
become anchylosed, with the consequent disappearance of the facial
suture, as, for instance, in the Devonian genus Phacops, this character
has appeared at the termination of a long phylogenetic line in which all
the earlier members possess functional facial sutures. The facial suture
is so characteristic of every order and every family of trilobites, save
the Mesonacidae, that one is forced to the assumption that it was a
character of the primitive stock from which all have sprung. It there-
fore seems necessary to assume that the ancestors of the Mesonacidae
possessed a functional facial suture, and that the absence of this character
in this group of genera is indicative of its terminal position in a long
phylogenetic line whose pre-Cambrian history is unknown to us. Since
such a character when once lost cannot be restored again, it would follow
that Paradoxides with its functional facial suture could not have origi-
nated from any member of the Mesonacidae. Might it not be assumed
that Paradoxides arose from a totally distinct phylogenetic line in a
different early Cambrian biologic province, perhaps southern Europe,
and later migrated into the North Atlantic province where it occurs
in strata generally younger than those bearing the Mesonacid faunas ?
Under such an interpretation it would be necessary to grant that some-
where Paradoxides may have been contemporaneous with at least a
portion of the Mesonacid faunas in North America, and this contem-
poraneity may even have extended to the North American shore of the
North Atlantic basin.

The paper adds much to our knowledge of these very ancient faunas
of the earth, and the author is to be congratulated upon the success of
his most persistent search for these rare fossil forms. Not the least
attractive portion of the paper are the twenty-two beautifully executed

half-tone plates.
5. W.

Elements of Geology. By Exiot BLACKWELDER AND Haran H.
Barrows. Pp. 475; figs. 485; pls.16. New York: American
Book Co., 1911.

This is not a manual or reference book, but an elementary textbook
intended primarily for use by young students in the high schools, acade-

474 REVIEWS

mies, and institutions of similar grade. The book was written in the
belief that it is the function of a text as well as the duty of a teacher to
develop in the student the power to reason. This spirit pervades the
work throughout.

The method is essentially analytical and the text explanatory rather
than descriptive. Abundant use is made of questions which are ingen-
iously devised to guide the student’s mental operations and to lead him
unconsciously through certain desired chains of reasoning. Many of
the questions are inserted in the text—a practice which makes the stu-
dent stop and think and, by causing him to tie his ideas together, inciden-
tally and unconsciously brings him to see the interrelation of the dif-
ferent geologic agents and processes.

The treatment throughout indicates a continuous desire to prevent
the student from forming hard-and-fast conceptions of processes and
geologic features that are necessarily often variable. There is a
steady determination to compel the student to maintain a critical open
mind and at the same time to draw close distinctions in the use of
variable terms, as in the relative heights of hills and mountains and of
plains and plateaus. Sometimes, however, this most laudable endeavor
threatens to overstep itself and lumber up the text with hypercritical
qualifications. In an elementary textbook where space is severely
limited unessential discriminations crowd out more weighty matter,
while the student on his part may come to give too much thought to
precision in little things at the expense of a grasp of great things. But
this is only another item in the ever-present question of where to draw
the line.

The text is clear, direct, and well written. In some cases, as in
chap. i, the opening paragraph is a bit wobbly, but when the initial
groping for just the right line is past and the topic is well under way,
the chain of ideas, like the language, flows evenly and gracefully along
without effort.

Poise and balance characterize the treatment of facts and principles.
The essential features are treated clearly though concisely, and the
minor features are subordinated or left out where their omission does
not weaken the presentation of the main topics. Unessential facts have
been carefully pruned. Keen discrimination is apparent here.

The departure of the authors from current practice in the arrange-
ment of material will be most conspicuously seen in the omission of
separate chapters on vulcanism and earthquakes. This was done
in the belief that volcanoes and especially earthquakes are exceptional

REVIEWS 475

and local phenomena and that although spectacular and ever interesting
to the popular mind, they are not entitled to the same space in such
a work as are the more general geologic processes. The main features
of vulcanism and volcanic rocks are, however, quite adequately treated
in the chapter on the composition of the earth, while volcanic moun-
tains as surface features appear in the very excellent chapter entitled
“The Great Relief Features of the Land.”

The proper handling of historical geology in brief space is a difficult
task. There is a great deal of ground to be covered and a great mass
of material to be judiciously picked over. Unless the work is well
done, the residue left is apt to be a dry bone skeleton with the flesh
and blood largely gone. In the historical portion of this work the
salient and vital points are made to stand out clearly. This is particu-
larly true of the life history. In part this is secured by a sprightly use
of paragraph headings to feature the various vicissitudes through which
life forms have passed in their long history. With these in mind, the
significance of the discussion is more readily grasped and the details
are more easily retained.

The authors have treated the Tertiary as a “Period,” giving it
the same rank in the geologic time scale as they do the Comanche or
the Cretaceous. After stating that it is divided into the Eocene, Mio-
cene, and Pliocene epochs, the Tertiary is discussed largely as a unit.
The Tertiary presents many rich problems for advanced students,
especially its mammalian evolution and its diastrophism, but these
are perhaps beyond the reach of a beginning class. The authors, believ-
ing that the points of newness or striking facts are largely over by the
time the Tertiary is reached, have apparently thought it best to curtail
the treatment and advance rapidly to the close of the history.

A feature which cannot be too highly commended is the extensive
use of three-dimension diagrams to portray the operation of geologic
processes. This, in the reviewer’s opinion, is much more expressive
than the ordinary style. The set of three block diagrams on p. 146
which picture the successive development of youthful, mature, and old
topography, illustrating not only the surface development of the streams
but the simultaneous lowering of the land toward peneplanation, shows
the possibilities of the method.

By reducing the size of the illustrations, a very large number have
been successfully introduced and add very greatly to the effectiveness
and attractiveness of the book. It is a veritable picture book with
most of the pictures new to geologic readers.

476 REVIEWS

Finally it may be said that the general scheme and mode of treatment
of the book follow the lead of the comprehensive treatise of Chamberlin
and Salisbury, and the fundamental views which give distinctive charac-

ter to that work find reflection in this.
R LSC,

Geology of the Kiruna District (2). Igneous Rocks and Iron Ore of
Kiirunavaara Luossovaara and Tualluvaara. Academical Dis-
sertation by Per A. Geter, for the degree of Doctor of
Philosophy. By the permission of the philosophical faculty
of the University of Upsala. Stockholm, 1910. Pp. 278;
2 geologic maps.

The district is in northern Lapland. The rocks, which are generally
regarded as pre-Cambrian, include greenstones, conglomerates, syenite
porphyries, magnetite ores, quartz porphyry, phyllites, sandstones, etc.
They are strongly folded and in general stand nearly vertical but other-
wise do not show pronounced metamorphism. The textures are well
preserved. A typical ore body is the one of Kiirunavaara which forms
the backbone of a mountain about 748 meters high. This ore body is
over 5 kilometers long and some 96 meters wide. Other ore bodies
are somewhat smaller. The ore zone is included between quartz por-
phyry and syenite porphyry. The minerals of the ore are magnetite,
hematite (subordinate), fluor-apatite, augite, amphibole, biotite, titanite,
tourmaline, zircon, etc. Generally there is enough apatite to place the
ore above the Bessemer limit.

The ore minerals are intergrown like those of an igneous rock and
contacts between ore and country rock are in places gradational. All of
the minerals of the ore except tourmaline are primary constituents of
igneous rocks near by. Rock textures indicate that the ore mass has
crystallized quite in the same way as an igneous rock—these include
trachytoidal flow structure, skeleton forms of magnetite, and the ophitic
distribution of augite. The ores are believed to be of magmatic origin
and the writer is inclined to the view that the associated syenites are
effusive in character. He does not agree with De Launey, who held that
the ores were deposited at the surface from gases and hot solutions by
pneumatolytic-sedimentary processes. The writer does not feel sure
as to the nature of the differentiation processes which have resulted in the

product, but does believe that such an origin is proven.

REVIEWS 477

The Edmonton Coal Field, Alberta. By D. B. Dowttnc. Canada
Department of Mines, Geological Survey Branch, 1g1o.
59 pages, 2 maps.

_ The area primarily considered is on the Saskatchewan River, in and
near Edmonton, but a short discussion of the surrounding coal fields
is included. The coal is lignitic or semi-bituminous, and occurs near
the middle and at the top of 700 feet of brackish water deposits, the
Edmonton formation, at the top of the Cretaceous, and in Tertiary
sandstone above. The lower horizon, the Clover Bar seam, is worked
at Edmonton, and 80,000,000 tons are estimated to be available in an

area of 14 square miles.
We Ae.

Preliminary Memoir on the Lewes and Nordenskiold Rivers Coal
District, Yukon Territory. By D. D. Cartrnes. Canada
Department of Mines, Geological Survey Branch, 1g10. 70
pages, 2 maps.

The development of the Whitehorse copper deposits was the incentive
for the investigation of the available coal resources in the district
described in this report. The important formations of the district
are the Braeburn limestone (carboniferous ?), the Laberge series, con-
glomerates, shales, sandstones, etc., and Tantalus conglomerates, Jurasso-
Cretaceous. Tertiary volcanics have broken through these formations
and overflowed them in many places. Important coking coal seams
occur in the Tantalus conglomerates and near the top of the Laberge
series, but they are available only near the navigable water, such as

the Lewes River and Lake Laberge.
Wiel:

Geology of the Nipigon Basin, Ontario. By A. W. G. WILson.
Canada Department of Mines, Geological Survey Branch,
IQIO. 152 pages, I map.

The region covered by this excellent report is underlain mainly by
Laurentian gneisses and granites, but scattered over it are areas of
greenstones and green schists, called Keewatin. A few bands of Lower
Huronian rocks are known. Lying on the eroded surface of these
formations is a series of conglomerates, sandstones, shales, and dolo-
mitic limestones classed as Keweenawan, although the author believes

478 REVIEWS

they might be younger than pre-Cambrian. The youngest rock is a
diabase, which occurs as intrusive sheets and flows. The evidence for
and against the diabase occurring as a volcanic flow is fully discussed,
the conclusion being that as now known they are basal residuals of
former extensive flows.

The glacial geology is briefly discussed, the author concluding that
ice erosion was very limited, except locally. The physiographic features
are considered, also the economic geology, but no deposits of any value
are known.

Wi Aes

The Geology and Ore Deposits of the West Pilbara Goldfield. By
H. P. Woopwarp. Bull. No. 41, Western Australia Geologi-
cal Survey. Pp. 142; 5 geological maps; 1 mining plan;
25 figs.

The first part of the bulletin is devoted to a general discussion of
the physiography, geology, and petrography of the district, which
occupies the triangular portion of the northwest division of the state
included between the Fortescue and Yule rivers. The southern part
of the area is a high tableland which drops abruptly to the wide, low
coastal plain forming the northern part.

The oldest rocks in the region are metamorphosed sedimentaries—
clay slates and shales—that have been intruded successively by dolerite,
gabbro, and granite. The last is thought to have altered some of
the clay slates and dolerites to crystalline schists. A period of sub-
sidence was accompanied by an outburst of volcanic activity in the form
of fissure eruptions of very fluid basic lava. Subsidence continued, and
marine beds are found above the last lava flow. Re-elevation and
denudation have given rise to the present topography. The various
formations are described in some detail, and petrological notes on
seventy specimens are appended.

The second part of the bulletin is devoted to a more detailed descrip-
tion of the country and the mining centers visited. The lodes are most
frequently found in the altered sedimentaries. They carry, in addition ©
to gold, varying amounts of pyrite, chalcopyrite, and galena. Little
evidence regarding the genesis of the lodes is presented. Much of the
material is of greater interest to the cneine et and the investor than

to the geologist.
A DPB:

REVIEWS 479

A Review of Mining Operations in the State of South Australia
during the Half-Year Ended December 31, 1910. No. 13.
Issued by T. DUFFIELD, Secretary for Mines. Adelaide, 1911.
J210)5 Bylo, Mp

This paper gives statistics on leases, claims, subsidies, men employed,
prices, and various industrial and technical features of the mining
districts of South Australia. Notes on recent development work,
including assays of samples and amount of boring, tunneling, etc., done
on various properties make up a large part of the review.

An interesting method of draining the southeastern district has been
approved by the government geologist. The plan is to sink borings
or shafts into a porous stratum underlying the swamp areas and allow
the water to escape through underground channels, saving the expense
of extensive ditches necessary for surface drainage. Small areas have
been drained into natural sink holes with very encouraging results.

eran IB)e aye

Report on the Iron Ore Deposits along the Ottawa (Quebec Side) and
Gatineau Rivers. By FRitz CIRKEL. Canada Department of
Mines,-Mines Branch. No. 23, 1909. Pp. 147; plates 5;
maps 2.

The area covered by this report is about goo square miles, extending
from Ottawa 100 miles up the Ottawa River and 83 miles up the Gatineau.
Deposits of magnetite and hematite ore have been known for over
sixty years and attempts have been made at various times to develop
them, but without success. The present report is the result of a com-
prehensive examination of the region to determine the possibilities of
development of the deposits. One important factor is the available

water power which is described in detail in the appendix.
E. R. L.

Maryland Geological Survey, Vol. VIII, t909. WILLIAM BULLOCK
CLARK, State Geologist.

This volume, which is entirely economic in its nature, contains the
following reports: Part I, “Second Report on State Highway Con-
struction,” by Walter Wilson Crosby, pp. 29-95; Part I, ‘“‘ Maryland
Mineral Industries, 1896-1907,” by Wm. Bullock Clark and Edward B.
Mathews, pp. 99-223; Part III, “Report on the Limestones of Mary-
land with Special Reference to their Use in the Manufacture of Lime

480 REVIEWS

and Cement,” by Edward Bennett Mathews and John Sharshall Grasty,

PP. 2257477:
E. ROE.

Missourt Bureau of Geology and Mines. Biennial Report of the State
Geologist for the Years 1909 and 1910. By H. A. BUEHLER AND
OTHERS.

The report contains a summary of the present and proposed work of
the bureau and the following chapters descriptive of work now in progress:
“The Principal Coal Fields of Northern Missouri,’ by Henry Hinds,
pp. 26-35; “Reconnaissance Work,” by V. H. Hughes, pp. 36-54; and
“The Geology of the Newburg Area,” by Wallace Lee, pp. 55-63.

E.R. L.

Mississippi State Geological Survey, 1907. ALBERT F. CRIDER,
Director.

The volume contains the following reports: Bulletin No. I, ‘Cement
and Portland Cement Materials of Mississippi,” by Albert F. Crider,
pp- 73; Bulletin No. II, “Clays of Mississippi, Part 1, Brick Clays and
Clay Industry of Northern Mississippi,’ by William N. Logan, pp.
255; Bulletin No. III, “The Lignite of Mississippi,’ by Calvin S.

Brown, pp. 71.
BoE:

The Geology of the Whatatutu Subdivision, Raukumara Division,
Poverty Bay. By JAMES HENRY ADAMS. New Zealand Geo-
logical Survey, Bulletin No. 9 (New Series). Wellington,
LO10: 7p. 48; maps 5;, plates.

The Raukumara division lies on the eastern side of the North Island
of New Zealand and consists of a series of rolling ridges of moderate
height separated by deeply cut river valleys. The rocks belong chiefly
to the Whatatutu series which are upper Miocene in age and which are
folded into irregular anticlines and synclines. Indications of oil have
been found at various points within the region and the object of the
survey was to obtain information as to the possibilities of development.
With this end in view the anticlines and synclines were mapped and
described with considerable care. Fossils are abundant in some locali-

ties but have received little attention in this report.
E. RoE:

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VOLUME XIX : ; NUMBER 6

‘EEE

JOURNAL or GEOLOGY

A_SEMI- QUARTERLY

EDITED BY

) THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
anes : With the Active Collaboration of

SAMUEL W. WILLISTON ALBERT JOHANNSEN WILLIAM H. EMMONS

Vertebrate Paleontology Petrology Economic Geology
STUART WELLER WALLACE W. ATWOOD ROLLIN T. CHAMBERLIN

Invertebrate Paleontology Physiography Dynamic Geology

ASSOCIATE EDITORS

SIR ARCHIBALD GEIKIE, Great Britain; GROVE K.GILBERT, National Survey, Washington, D.C.
HEINRICH ROSENBUSCH, Germany CHARLES D. WALCOTT, Smithsonian Institution

THEODOR N. TSCHERNYSCHEW, Russia HENRY S. WILLIAMS, Cornell University

CHARLES BARROIS, France JOSEPH P.IDDINGS, Washington, D.C.

ALBRECHT PENCK, Germany _ JOHN C. BRANNER, Stanford University

HANS REUSCH, Norway igs RICHARD A. F. PENROSE, Jr., Philadelphia, Pa,

GERARD DEGEER, Sweden WILLIAM B. CLARK, Johns Hopkins University
“ORVILLE A. DERBY, Brazil WILLIAM H. HOBBS, University of Michigan

T, W. EDGEWORTH DAVID, Australia FRANK D. ADAMS, McGill University

BAILEY WILLIS, Argentine Republic CHARLES K. LEITH, University of Wisconsin

SEPTEMBER-OCTOBER, to11

CONTENTS

_ PRELIMINARY STATEMENT. CONCERNING A NEW SYSTEM OF QUATERNARY

LAKES IN THE MISSISSIPPI BASIN - - - - - - - ~ Evucene Westey SHaw 481
GRAVEL AS A pore Ne ROCK = ye Joy Lyon Rica | 402
THE CRETACEOUS AND TERTIARY FORMATION OF WESTERN NORTH DAKOTA.

BUTS Bz SPTVD RONG MUON TSN eG, LEONARD 507
ON THE GENUS SYRINGOPLEURA SCHUCHERT - - - - - - Grorce H.Gimty 548
PRELIMINARY NOTES ON SOME. IGNEOUS ROCKS OF JAPAN. I - = -S. Kézu s55
“PRELIMINARY NOTES ON SOME IGNEOUS ROCKS OF JAPAN. II-°- -S.Kézu- 56x
PRELIMINARY NOTES. ON SOME-IGNEOUS ROCKS OF JAPAN. Ill - -S. Késu 566
“TRAE NV ATTEN ASSIS Sa Silence ei gr en are eevee ca pi, Peer cee Seat

Che Aniversity of Chicago press
CHICAGO, ILLINOIS
AGENTS:
'- THE CAMBRIDGE UNIVERSITY PRESS, Lonpon anp EpinsurcH
WILLIAM WESLEY & SON, Lonpon
TH. STAUFFER, Le1rzic \
' THE MARUZEN-KABUSHIKI-KAISHA, Toxvo, Osaka, Kyoro

Che Journal of Geology

Published on or about the following dates: February 1, March 15, May 1, June 15,
August 1, September 15, November 1, December 15.

Vol. XIX CONTENTS FOR SEPTEMBER-OCTOBER, ft No. 6

PRELIMINARY STATEMENT CONCERNING A NEW SYSTEM OF QUATERNARY LAKES IN THE

MISSISSIPPI BASIN” - - - - - - - - - - - - - EuGENE WESLEY SHAW 481
GRAVEL AS A RESISTANT ROCK - - - - - - - - - SEAS - - JoHn Lyon RicH 492
THE CRETACEOUS AND TERTIARY FORMATIONS OF WESTERN NORTH DAKOTA AND EASTERN

MONTANA - - - - - - - - - - - - - - A. G. LEONARD 507
ON THE GENUS SYRINGOPLEURA SCHUCHERT - eee - - - - = GroRGE H. Girty 548
PRELIMINARY NOTES ON SOME IGNEOUS ROCKS OF JAPAN. I - - - - - - - 8. Kézu 555
PRELIMINARY NOTES ON SOME IGNEOUS ROCKS OF JAPAN. II - - - an eS - 8. Kézu 561
PRELIMINARY NOTES ON SOME IGNEOUS ROCKS OF JAPAN. II - - - - - -S. Kézu 566
RE VDE W'S ah aie einen as lar at ar (Mie ei oie UN hcesicsobeon | (Vce (gas mi etna Stee Tae ED ONS Hes i se LIA 6)

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THE

IOURNAL OF GEOLOGY

SLIEVMIBER OCLOBE FR, Tor

PRELIMINARY STATEMENT CONCERNING A NEW
SYSTEM .OF QUATERNARY LAKES IN THE
MISSISSIPPI BASIN*

EUGENE WESLEY SHAW
U.S. Geological Survey

It is a significant fact that in but few places do the Mississippi
and Ohio rivers flow on consolidated rock. Throughout most of
their courses they flow over bodies of silt, sand, and gravel 50-100
feet in thickness. The lower half or third of each tributary also
flows over a thick unconsolidated mass, which is similar to those
on the larger streams, except that in general it is less coarse. For
examples, the Wisconsin River in southwestern Wisconsin is
working 50 feet or more above a hard rock channel; Big Muddy
River in southern Illinois flows between mud banks in a broad,
shallow valley with a buried channel 4o feet below; and away east
in Pennsylvania the Monongahela does not flow over bed-rock
at any point within the limits of the state. Thus, not only the
valleys of the Mississippi and Ohio, but the lower part of almost
every tributary valley in the northeast central states, and probably
in a considerably larger territory, is partly filled with loose sedi-
ment, and in Illinois, Indiana, and Kentucky the filling on the
tributary streams consists largely of clay, a brief description and
interpretation of which are the objects of the present paper.

t Published by permission of the Director of the U.S. Geological Survey, Washing-
ton, D.C. A more complete description is to be published by the Ill. Geological
Survey.

481

482 EUGENE WESLEY SHAW

The upper surface of the clay forms a terrace which is generally
so broad and so low that it is scarcely perceptible, though it is
commonly separated from the flood-plain by a low scarp. This
terrace is almost perfectly horizontal, and since the flood-plain
rises up stream the terrace and flood-plain finally merge. However,
since the flood-plain itself on the tributaries is nearly horizontal
(for the streams have but little fall) the flood-plain and terrace
on some rivers are distinct for 40 miles or more, although vertically
they are almost nowhere more than 4o feet apart.

Another characteristic of these valleys is that in places they
anastomose. Many valley floors connect through divides with
neighboring valley floors. Some of the connecting parts are broad
and resemble bays in the sea; others are narrow and strait-like;
and the severed parts of the divide are massive. In many places
the flat valley floor surrounds hills that stand up sharply like
islands. These features of the lower parts of valleys tributary
to the Mississippi and Ohio—the broad bottoms in hilly country,
and the irregularly branching valleys—point toward valley filling.
And well-sections and exposures support this indication, showing
that bed-rock is far below the present streams.

Detailed description of the clay.—The clay varies from greenish-
gray to purplish-gray in color and from medium plasticity to
“oumbo.” The lower part is evenly stratified.and in places
finely laminated. The upper part has less distinct stratification
and is characterized by irregular concretionary masses of lime.
Around the border and in the up-stream parts of the deposit
there are lenses of fine sand, but considering the formation as a
whole, sand forms a remarkably small part. With the exception
of the concretionary lime, some particles of which are as small as
sand grains, most of the deposit is without perceptible grit. In
ground plan the bodies of clay are very irregular and even anas-
tomosing—shapes that would be expected of valley fills in a country
of medium to low relief (see Fig. 1). The surface of the clay in
each valley is horizontal and lies from 5 to 75 feet above low water.
But the altitude varies from valley to valley. Near Cairo the
surface of the clay is 345 feet above sea; at Galena, Illinois, 400-
miles up the Mississippi, it is 650 feet; and there is a corresponding

QUATERNARY LAKES IN THE MISSISSIPPI BASIN 483

increase in altitude up the Ohio. Thus, although the deposit along
each tributary and its branches is usually isolated and lies at a
different altitude from that on every other stream, the different
bodies have such a regular arrangement and have so many char-
acters in common that there can be little question but that they are
closely related, and they appear to be in large part lake deposits,
but in smaller part stream deposits, so that they may be referred
to as fluvio-lacustrine.

IS MILES.

Fic. 1.—Lake Muddy, in southern Illinois. One of a series of lakes, now extinct,
caused by a rapidly growing valley filling on the Mississippi and certain other streams,
the filling forming a dam across the mouths of tributaries. The lakes stood at dif-
ferent altitudes, being controlled by the altitude of the Mississippi at their various
outlets; each was in a continual state of fluctuation, the position of its surface at any
moment being controlled by the stage of the Mississippi, and for a part of the time
each was intermittent. The narrow part of Lake Muddy near the outlet was in a
narrow, high-walled part of the valley, due to uplifted hard rocks. With the approach
of every flood on the Mississippi water gushed up through the narrow part of the lake
to the broader inland, a part carrying with it fine sand which, with interbedded lake
silt, formed a delta at the lower end of the lake, fronting toward the head of the lake.

484 EUGENE WESLEY SHAW

Shore features were generally poorly developed, though 12-15
miles northeast of Madisonville, Kentucky, 60 miles by water from
the Ohio River, there are beautifully developed and well-preserved

each-ridges. These ridges are very symmetrical, being 20-50
feet wide, and 8 to 10 feet high (see Fig. 2). They are composed
of sand and fine gravel and are situated across the mouths of
small tributary valleys. The reason for the excellent development
of gravel ridges at this place is the generous available supply of
loosely cemented conglomerate, probably Late Tertiary in age, com-
posed largely of well-rounded quartz and flint pebbles. Elsewhere
there was not a large amount of well-rounded pebbles within
reach of the lake and so far no other well-developed ridges have
been found. At numerous places where the bank of the lake was
easily eroded there is some suggestion of wave cutting, but the
evidence has been almost obliterated by recent erosion. One
reason for the general poor development of shore features is that
owing to the rise and fall of the rivers the lakes were continually
fluctuating and were intermittent for a part of the period of their
existence. Thus, particularly in districts of low relief, the shores
of the lakes did not stand in one position long enough to develop
shore features.

Good collections of fossils were obtained, the fauna consisting
of nearly a score of species of gastropods and lamellibranches, and
undoubtedly many more species, including perhaps vertebrate and
plant remains, might be found. Most of the forms collected inhabit
lagoons and the quiet parts of streams. One of them (Campe-
loma) is a scavenger living in decaying animal matter. Others
frequent lily ponds. Some, such as Vertigo, are northern forms,
being found at present from Wisconsin northward.

The lime masses are probably secretions of blue-green algae,
though at present they show little organic structure. They are
more abundant in the thinner parts of the formation, and this may
be correlated with the fact that lime-secreting algae flourish in
very shallow or intermittent waters.

Previous work.—Bodies of this clay have been regarded as glacial
drift; a lowland phase of the loess; an old normal flood-plain
deposit; a back-water deposit from glacial floods on the larger

QUATERNARY LAKES IN THE MISSISSIPPI BASIN 485

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Fic. 2.—Part of Madisonville, Ky., topog. sheet, U.S. Geol. Survey, showing
beach of extinct Green Lake (named from Green River which now drains the lake
bed) and an ‘‘island hill.” The thickness of the lake deposit here is about 30 feet
and the surface 381 to 385 feet above sea. The “‘island hill” is one of many peculiar
partly-buried hills which rise sharply from the flat surface of the material deposited
around them so that they bear a strong resemblance to islands rising above a water
surface. The beach ridge shows well in the topography between Philips’ store and
the McLean County line.

486 EUGENE WESLEY SHAW

streams; a deposit due to subsidence; a deposit due to climatic
change; and in southwestern Wisconsin a closely related but pre-
dominantly stream-laid deposit has been attributed to glacial
floods and deposits in the Mississippi Valley.

The clay is not glacial drift, for it contains no stones and little
sand; and much of it lies outside the glacial boundary. More-
over, it is found only in the lowest places and its upper surface is
horizontal without regard to the underlying surface of hard rock.
It is not loess, for it fills all depressions up to certain altitudes and
is not found at higher positions. Its thickness and others of the
characters already described show that it is not a normal flood-
plain deposit. It could scarcely be a simple back-water deposit
from glacial floods without the help of a valley train, because that
would require that the rivers have a sustained depth of about two
hundred feet for the thousands of years it must have taken the clay
to accumulate. A subsidence of the surface might lead to the
development of a few bodies of clay having the shape and arrange-
. ment of those under discussion, but warping so complex as to cause
the regular arrangement and shape of so many bodies of clay would
be inconceivable. Nor could the deposits have been produced by
climatic change, for such deposits slope down stream and these
are horizontal. Finally, the limited up-stream extent of the clay,
the fineness of the material, the horizontality of the surface, and
the fact that the clay abuts against thick bodies of coarser material
on the large rivers, indicate that most of the clay accumulated in
lakes produced by valley fillings, the master drainage lines of
the region. In order to understand the cause and history of the
lakes it is therefore necessary to look into the history of the large
rivers.

Valley filling on the Mississippi and Ohio.—The deposits on the
Mississippi and Ohio consist principally of sand, but there is con-
siderable gravel and silt, the gravel being more abundant at the
base and the silt at the top. Most of the material lies below extreme
high-water stage, and hence the surface forms a flood-plain, but
here and there bodies ot sand and gravel stand about 30 feet above
the reach of high water, the upper surface in such places forming
a terrace at the altitude of the valley filling on near-by tributaries.

QUATERNARY LAKES IN THE MISSISSIPPI BASIN 487

Apparently the river valleys were once filled to a position as high
as the surface of the filling on the tributaries, but have now been
partly cleared out, the surface of the fill being lowered about 30
feet. The part remaining is about 150 feet thick and extends
about 120 feet below low water, the range between high- and low-
water stages being about 30 feet (see Fig. 3).

In this connection it seems worth while to note that when the
discharge of a stream is increased, the vertical distance between
the bottom of the channel and the flood-plain is also increased,
and this comes about not alone by scouring out the channel, but
also by building up the alluvium. Thus, without any change
in size of load, it is possible to produce thick alluvium by simply
“increasing the volume of water.

To return to the lakes themselves: they differed from most
bodies of quiet water in that the position of the surface varied
greatly every year, for it was controlled by the various stages of
the rivers. If the range between high and low water had been the
same that it is now the surfaces of the lakes would have fluctuated
between limits about ro to 4o feet apart. But the lakes formed a
huge reservoir so that with the same discharge as at present the
rivers would not have risen nearly so much in times of flood.

Indeed, to raise the surface of the lakes and rivers one foot, it
took over one hundred billion cubic feet or nearly a cubic mile of
water; moreover, every rise of 5 or to feet would double the dis-
charge of the rivers, so that tremendous floods could be taken care
of without great increase in depth of water.

Terminology.—It seems probable that the rather extensive
development of deposits and resulting topographic features such
as are described in this paper will lead to the introduction of some
new descriptive terms. Perhaps it will be found convenient to
use “‘contragradation”’ or “‘dam gradation” for that kind of stream
aggradation which is caused by an obstruction, or, more broadly,
decrease in velocity, and perhaps to invent still other terms for
the aggradation due to increase in load and decrease in volume.
In case the obstruction develops so rapidly as to produce ponded
water, such as is described in the present paper, the deposit is on
the whole very fine-grained and the top nearly horizontal though

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488

QUATERNARY LAKES IN THE MISSISSIPPI BASIN 489

more or less concave. For the resulting topographic feature,
the bottom of Muddy River Valley may be taken as a type and
Muddy may be an acceptable name for it, referring, as the name
does, both to a particular type and to a principal character of
the deposit, and the streams which flow over it, and also to the
general character of the country where the feature is developed.
On the other hand, in case aggradation keeps pace with the
growth of the dam the material is in general coarser and the upper
surface rises up stream, though at a less rate than the original
stream channel. For this topographic feature the surface of the
deposit forming a low terrace along Big Sandy River in eastern
Kentucky may be taken as a type and called a Sandy. Perhaps
also it will be found desirable to speak of the island-like hills sur-
rounded by the deposit as Island Hills, and the hill bearing the
town of Island, in Kentucky, may be taken as a type.
Summarizing.—Vhe inferred history of the lake deposit reads
about as follows: In middle or late glacial time the rivers were
flowing on beds about too feet below their present ones. Whether
this great depth was attained in an interglacial epoch by a regional
uplift or was reached through the deep scouring of glacial floods
has not yet been determined. The tributaries entered the flood-
plains of the Mississippi and Ohio on channel bottoms only about
40 feet lower than those in use today and their flood-plains were
near the position of their present channel bottoms, these positions
being controlled by low- and high-water stages on the master
streams. As at present, at low-water stage there was no standing
water in the tributaries, but at high water the deep channels were
filled by back water from the rivers, thus forming long, narrow
winding lakes. When aggradation began on the Mississippi and
Ohio, both low- and high-water marks on them and on the tribu-
taries rose. At low water there were embryo, perennial lakes in the
channels of the tributaries at their mouths and at high water the
flood-plains were covered more deeply than before. The area
covered both at low- and high-water stages gradually extended until
low-water stage reached the altitude of the former flood-plain.
From this time on there were perennial bodies of quiet water of
considerable size on each tributary, and wedge-shaped masses of

4QO EUGENE WESLEY SHAW

lake deposit about 80 feet thick at the lower ends and thinning out
to a feather edge up stream, accumulated on the old flood-plains.

Nearly all the material deposited in the lakes was fine sediment
such as would be carried in suspension, and the lakes seem to have
been filled with this material up to certain concordant positions,
probably to the natural position of a flood-plain or just below the
high-water mark of the time.

A A
Re 0) QGri37FLOop-PLAIN SILT
SSS LAKE DEPOSIT

O | 2 3 4 5 MILES

Fic. 4.—Diagram showing arrangement of principal deposits and surface features
along Beaucoup Creek, Perry and Jackson counties, Illinois. The filling thickens
and the flood-plain becomes narrower down stream. When the lake became extinct
the bed became a great swamp. The stream first cut into the lower end of the fill,
draining that part of the swamp and developing a narrow flood-plain below the sur-
face of the lake silt. With further downward cutting the new flood-plain was lowered
and extended up stream and the swamp area reduced. Meanwhile, stream deposits
continued to accumulate at the upper end of the lake bed. Many other valley bot-
toms are similar, having a peculiar swampy central portion.

QUATERNARY LAKES IN THE MISSISSIPPI BASIN . 491

When the Mississippi and Ohio finally became not only able to
carry all the load delivered to them but a little more, they began
to cut down again. Perhaps even before this time the lakes had
become intermittent, being drained except at times of high water,
for they were almost filled with sediment. The great flat lake
bottoms became swamps, and channels began to deepen again at
the former outlets. At the same time the swamps themselves
began to be drained at the lower ends. The process of swamp
draining has continued to the present time, and on medium-sized
streams there now remain only 10-20 miles of swamp, the lower
20-50 miles having been drained (see Fig 4).

GRAVEL As: A RESISTANT ROCK

JOHN LYON RICH
Cornell University, Ithaca, N.Y.

INTRODUCTION

The thesis which this paper will endeavor to establish may be
stated as follows: Gravel, in its relation to the agencies of denudation,
is, under certain geological conditions, a highly resistant rock. To
these agencies it will, in general, offer greater resistance than ordinary
igneous or sedimentary rocks, with a few possible exceptions. On
the validity of this thesis hinge important deductions as to the
normal course of topographic development in cases where such gravel
plays a prominent part in the geological structure of a region.

It is my purpose (1) to point out the theoretical reasons for the
resistant nature of gravel deposits; (2) to show from an actual
occurrence in nature that the gravels do behave as the theoretical
considerations would lead us to expect; and (3) to sketch, by way
of suggestion, the normal course of development of topography in a
region where alluvial fans of coarse material are accumulating at
the base of mountains. By way of suggestion there will be further
a brief application of the principles brought out to certain well-
known topographic features.

Except for the descriptive portion of the paper, which will be
clearly distinguished, the article is an analytical study made mainly
for the purpose of determining the influence of certain types of rocks
upon the processes and rate of denudation, and of calling attention
to what appears to be a normal cycle of denudation and the topo-
graphic development of mountains in an arid region, and to a
lesser extent in a humid region as well.

At the present time no attempt will be made to review exhaustively
the literature of the subject.

1 Published by permission of the Director of the U.S. Geological Survey.
402

GRAVEL AS A RESISTANT ROCK 493

RESISTANT QUALITIES OF GRAVEL

It is natural to look upon gravels as weak rocks which may easily
be removed by the agencies of denudation. While this is doubt-
less true for sand or possibly even for fine gravel, it is a view which
does not hold true of gravel of a coarser nature such as accumulates
at the base of mountain ranges either in arid or humid climates, or
of river gravels of the coarser type such as the Lafayette gravels
of the Mississippi Valley.

There are two essential reasons for the resistant quality of gravel
as regards denudation. These are: (1) the selected nature of the
material; (2) its porosity. As regards the first of these, gravel is a
composite rock made up of units, each of which is selected on the
basis of its ability to withstand the action of the agencies of de-
struction to which all rocks are subjected. These agencies of dis-
integration are both mechanical and chemical. With respect to
the mechanical, gravel may be looked upon as a residue which has
survived the rolling, pounding, and abrasion incident to its trans-
portation along the stream course, an experience which, if the jour-
ney be a long one, effectively grinds down and destroys all but the
most resistant of the materials subjected to it.

From the standpoint, also, of rock decomposition gravel is par-
ticularly resistant, for it is a rock whose component materials
are severally selected on the basis of their ability to withstand such
decomposition. In a region of normal development where there
has been no interference with normal conditions by such accidents
as glaciation, the stream gravels represent, in the main, only rocks
or fragments of rocks which, by virtue of their resistant qualities,
have been able to survive unchanged the decomposition and
mechanical disintegration which has effectively destroyed the rock
surrounding them. They have undergone successfully the ordeal
which has destroyed the neighboring rock. They are therefore
still able to resist further subjection to the action of the same agen-
cies of change.

Physically also, gravel is especially fitted to resist disintegration
because in it the component fragments are reduced to compact
units unbroken, as a rule, by fractures or other lines of weakness.
The surfaces are generally smoothed and give little opportunity for

404 JOHN LYON RICH

the attack of frost or for the entrance of percolating water, while
the comparatively small size of the units diminishes the activity of
insolation as a disintegrating agent. For these reasons, while a
massive quartzite, for instance, may be as resistant as gravel to
disintegration due to either mechanical abrasion or chemical decom-
position, it will be more likely, especially if in larger masses, to
suffer more from the effects of insolation and frost.

From the foregoing it is clear that stream gravels, particularly
the coarser ones, may properly be looked upon as concentrates of
the most resistant elements of the rocks from which they are derived.
It follows that a gravel of such a nature will be more resistant to the
agencies of disintegration than the original rocks. From its very
nature and origin a gravel deposit should be expected to offer great
resistance to the normal agencies of sub-aerial denudation. This
resistant quality is particularly significant in the development of
the topography of gravel deposits, since, disintegration being at a
minimum, bodily removal of the component units of the gravel is
necessary for their reduction; and, as we shall point out later, bodily
removal, too, is at a minimum except along the immediate courses
of good-sized streams. In the latter situations this may be readily
accomplished, but away from the actual stream course the removal
of the material must necessarily be very slow. The importance
of this point in relation to the dissection of the alluvial fans along
the base of a mountain range will be more fully elaborated on a
subsequent page.

The second characteristic of gravels which makes them resistant
to the disintegrating and erosive forces which would wear them
down is their porosity and the consequent comparatively slight
development of surface drainage on the gravel areas. A gravel
deposit of moderate coarseness offers the maximum of favorable
conditions for the absorption and storage of the rain which falls
upon its surface. This hinders the formation of small surface
streams, and since, as we have seen, disintegration is at a minimum,
and the removal of the gravel is almost entirely dependent upon the
transporting action of such streams, the gravels are doubly pro-
tected from removal. %

From the foregoing theoretical considerations we should expect

GRAVEL AS A RESISTANT ROCK 495

that gravel would be one of the most resistant of rocks as far as
its relation to the processes of disintegration and removal is
concerned.

Compare, for instance, the relative ease with which weathering
and erosion break up and remove the rocks from an area of granite
and from one of moderately coarse gravels in a similar situation.
In the case of the granite there is always a greater or less number of
joints or fissures through which water may enter and perform its
work of disintegration either by direct chemical decomposition or
by the subsidiary agency of frost. In contrast to this there are
the smooth, usually fissureless surfaces of the gravel units. The
granite is made up of a variety of minerals, some of which are easily
attacked by the weathering agents. Some, it is true, are as resist-
ant as the most resistant components of the gravel but in every
case these are small, being limited in size by the texture of the
granite. There is too, in a rock of complex mineral composition,
the factor of pulling apart of the mineral grains by differential
expansion and contraction.

The less resistant minerals, by weathering away and breaking
down, leave the harder and more resistant ones free to be removed
by the surface waters. Since, in general, the size of the grains is
comparatively small, in a granite scarcely exceeding one centimeter
in diameter, the resistant materials are readily removed by the
s'reams in the form of sand, while the products of the more thor-
ough disintegration of the less resistant minerals are easily carried
away in suspension or solution or may even be, in considerable
measure, picked up and carried off by the winds.

Thus we see that a granite is much more vulnerable to the
attacks of the weathering agencies than a coarse gravel. What
is true of granite is also true in varying measure of any of the less
resistant sedimentary or igneous rocks, such as shale, soft sand-
stone or limestone, diorite, etc. In the case of quartzite and cer-
tain of the lavas it is a question which would disintegrate more
rapidly, these or the gravel. The latter has in its favor, as a resist-
ant rock, the factor of porosity and the slight effect of insolation.

All the above considerations apply particularly when the slope
is low. On very steep slopes the lack of coherence of the gravel,

JOHN LYON RICH

i
Cy
a
us

aaers

aH
Be:

Bees

of
¢

¢ the features

show

Wee

N.M

The gravel area is shown by the dotted pattern.

’

gle

ilver City quadran

1.—A portion of the S
the text.

Fic.
described

GRAVEL AS A RESISTANT ROCK 497

combined with the effect of gravity and the rapid mechanical
erosion, would doubtless cause more rapid removal of gravel
than of granite on account of the dominance of the factor of bodily
transportation.

PIEDMONT GRAVELS NEAR SILVER CITY, NEW MEXICO

Near the town of Silver City, N.M., best shown between there
and the smaller town of Central, seven miles directly to the east
(see U.S.G.S., Silver City quadrangle), there lies a gravel deposit
of Piedmont nature which presents points of particular interest
in connection with the thesis just presented. The road from Silver
City to Central follows closely along the inner or mountainward
margin of this deposit (Fig. 1) which extends from here southward
for 40 or 50 miles as a part of the gravel fan of a great interior basin
which, with its tributary basins, covers a large area in the south-
western part of the state.

The gravel plateau, as it will be called, in the portion under
consideration between Silver City and Central, has a slope to the
south of about too ft. per mile and strikes approximately east and
west. It is characterized by great uniformity and evenness as
seen from any point on the plateau surface. One sees merely a
monotonous plain of gravel, horizontal as one looks to the east or
west, but sloping always toward the south. This appearance of
great evenness applies, however, only to the remnants as seen from
a point on the plateau surface, for, particularly near the northern
or mountainward margin, it is considerably dissected by streams
which, flowing outward from their sources in the mountains, have
carved long, usually nearly straight and parallel valleys down the
dip of the plateau (Fig. 2). These valleys are cut to a depth
of about 150 ft. at the maximum. As one follows them out toward
the desert plain they gradually become shallower and finally dis-
appear altogether. Degradation there gives place to aggradation.

The gravel of the plateau is composed of rocks found in place in
the mountains and the whole character and relationship of the
deposit points clearly to its origin as a Piedmont accumulation of
gravel spread out from the adjacent mountains to the north at some
earlier time before dissection set in.

4098 JOHN LYON RICH

While from its nature as a Piedmont accumulation, the gravel
of the plateau has not suffered complete elimination of the less
resistant elements, it is, nevertheless, an assorted mass in which
rocks of the more resistant kinds strongly predominate. A list
of a few of the more common of these will give a fair idea of the
nature of the gravel and of the extent to which the more resistant
rocks dominate. ‘The list follows: green quartzite, white quartzite,
light-colored rhyolite, basalt, diorite, epidotized granodiorite, garnet
rock, and magnetite from the Hanover ore deposits.

Fic. 2.—Looking down one of the valleys which crosses the gravel plateau from
the lowland to the desert beyond. Note particularly the character of the valley;
its narrowness and lack of tributaries. Compare this with the broad valleys developed
on the bed-rock of the lowland as shown in Fig. 3. Lone Mountain in the background.

The coarseness of the material varies. Individual bowlders of
large size are buried in a matrix of smaller bowlders, pebbles, and
sand. This combination gives a rock of very porous nature,
capable of absorbing quickly the water which falls uponit. At the
same time the removal of the finer material of the matrix leaves
the coarser bowlders and pebbles concentrated at the surface where
they form a very effective protective covering—effective against
either rain erosion, wind, or decomposition.

The most conspicuous feature in connection with this plateau
is the fact that it is now separated by a lowland from the moun-

GRAVEL AS A RESISTANT ROCK 499

tains which supplied the material for its construction. Nor is this
lowland the site of a stream valley. It runs, on the contrary,
parallel to the strike of the beds and is crossed directly by the
course of all the streams which flow from the mountains out through
the dissected plateau to the desert beyond.

A good idea of the nature of the lowland may be gained from the
photograph, Fig. 3 (see also the map, Fig. 1). This shows the low-
land in the foreground and to the left; the even-topped gravel
plateau on the skyline; and, sloping down toward the observer,

Frc. 3.—Looking southeast from the Central road three miles east of Silver City.
This view shows clearly the even-topped gravel plateau and its inward slope toward the
lowland in the foreground.

the inner scarp of the plateau facing the lowland at the divides
between streams. The view is looking southeast from the Central
road three miles east of Silver City.

On.the interstream ridges the difference in elevation between
the inner lowland and the tops of the plateau surface varies between
50 and roo ft. In going northward along the tops of the divides,
toward the mountains, one must travel from 3 to 2 miles before he
again encounters ground as high as the tops of the gravel plateau.
If the dip slope of the plateau surface is projected across the low-
land toward the mountains the present land surface is not inter-
sected within a distance of about 4 miles, on the average, from the

500 JOHN LYON RICH

general line of the gravel plateau. Such a projection may be
assumed to be a minimum original slope, for it makes no allowance
for an increased slope of the plateau surface nearer the mountains,
as must have been the case if the gravels once covered the lowland.
This feature is illustrated in the two profiles shown in Fig. 4,
drawn to scale from two different points well out on the plateau
northward across the lowland to the base of the mountains.

Amile E of Cross Mt
/Jountains.

Lowland
Gravel limit
Plateau Surface

Lrmiles N of Apache Jee

$000

Gravel Limit

Lowland

aoe

= yy,

1 A 1
Horizontal Scale in Niles

o
ie

Verétcal Scale 17 Feet.

Fic. 4.—Profiles across the gravel plateau and the lowland from points on the
desert to the foot of the mountains, showing the projected gravel surface and the
relations of the gravels to the mountains.

With topographic relations as they are at present the nearest
possible source of the gravels of the plateau is separated from it by
a lowland averaging 4 miles in width. It will be at once evident
that, at the time of the formation of the plateau, the lowland could
not have existed in its present relation. Any one of three things may
have happened to bring about present conditions: (1) The gravels
may have been removed by erosion from the area between their
present limit and the mountains; (2) there may have been faulting
by which the lowland was relatively lowered; or (3) the mountains

GRAVEL AS A RESISTANT ROCK 501

may have worn back and the lowland developed by differential
erosion since the deposition of the gravels.

Opposed to the first of these alternatives is the fact that the
gravel plateau ends abruptly along a relatively straight line. There
are no outliers of gravel between this general line and the mountains.
It is highly improbable that streams flowing nearly parallel and not
more than a mile apart should strip all signs of the gravels from the
upper four miles of their course, while in their lower course, where
they flow across the gravel plateau, they should be in relatively
narrow valleys with almost no tributaries and should have done
little more than to cut their way through the plateau without
having. been able to widen their valleys to any great extent (Fig. 2).

A second objection is the fact that the line of contact between
the gravels and the underyling rock slopes upward toward the moun-

Plate

= — sf
Profile of Stream.

Fic. 5.—Sketch showing the relation between the gravels of the plateau and the
underlying rock which indicates that the gravels néver reached much nearer the moun-
tains than now.

tains at such an angle that it would intersect the projected line
of the plateau surface at a point not far within the present limit of
the gravels (see Fig. 5). In other words the gravels thin toward
the mountains at such a rate that they would wedge out within a
short distance from their present limit, and the lowland is accord-
ingly developed in the bed-rock.

A third objection is raised by the fact that in the gravels of the
plateau there are aggregations or nests of huge lava bowlders,
some of them 15 feet in diameter, which indicates that the moun-
tians must at one time have been closer, for bowlders of such size
are too large to be carried far by water, particularly by water
flowing on a slope of too ft. per mile, which is approximately that of
the plateau surface.

The second alternative, faulting, seems highly improbable, for
there is no evidence whatever of the presence of faults along the

502 JOHN LYON RICH

line between the gravels and the lowland. At Silver City a tongue
of the gravel plateau extends with accordant grade directly across
the line of any fault which might have uplifted the gravels farther
east. Further conclusive evidence of the lack of fault relation-
ships of the lowland is furnished by the fact that the contact
between the gravels and the underlying rock runs down the valleys
and up across the interstream ridges in a perfectly normal manner,
and with such wide divergence from a straight line as to preclude
the possibility of an explanation by faulting.

The failure of the first two hypotheses to account for the inner
lowland leaves only the third, that of differential erosion. This
calls for, first, the formation of the plateau as a Piedmont plain of
accumulation at the base of the mountains; later, the cessation of
active aggradation, possibly because of a lowering of the moun-
tains through erosion; the initiation of a degradational phase of
activity; and finally, the gradual erosional retreat of the mountain
front and the reduction of the intermediate land at a rate faster
than that of the gravels, leaving them standing in their present
relations.

Important in this connection is the nature of the rock composing
the lowland. It is, in the main, a series of soft Cretaceous shales
cut by dikes of a moderately resistant igneous rock: In parts of
the lowland the shales are absent and the bed-rock is igneous.
This, however, makes little difference in the nature of the resulting
topography. Everything is worn down to a nearly uniform level
lower than that of the gravels.

A discussion of all the possible causes of the change in the phase
of activity from one of aggradation to one of degradation would
be out of place here. Two such may, however, be mentioned. The
first is change in climate, the second, a lowering of the mountains
by erosion with consequent relative increase in the factor of decom-
position, over that of disintegration and transportation, brought
about by the lessened slope.

If the same process of differential erosion continues, the moun-
tains will eventually become much reduced in height while the
gravels, suffering less by erosion, will stand relatively higher and
may finally come to dominate the topography of the surrounding

GRAVEL AS A RESISTANT ROCK 503

country. With respect to the drainage to the south, the extent to
which this process can be carried is limited by the base level of the
interior basin to which the streams are tributary.

A factor which must profoundly affect the topographic develop-
ment of the whole region is the Gila River with its tributaries which,
passing within 20 miles of Silver City, to the northwest, drains
a large proportion of the mountain area. The Gila drains directly
to the sea, and being a good-sized permanent stream, whose vailey
is some 1,600 ft. lower than the gravel plateau, it is actively pushing
its headwaters southeastward into the drainage area of the interior
basin in which the plateau is situated. The divide, in one place,
now lies only 6 miles from the gravel plateau and is only 4oo ft.
higher. The Gila affords opportunity for the free removal of the
waste from the mountains. Short and steep slopes combine to
increase its effectiveness.

Eventually the normal outcome of processes now in operation
should be that the mountains would become lowered; the interior
lowland between the plateau and the mountains would, by capture,
become tributary to the Gila; and the plateau itself, remaining
higher on account of its superior resistance to erosion, would ter-
minate in a scarp overlooking the lower lands to the north.

SIMILAR FEATURES IN OTHER REGIONS

Other areas are known where gravel deposits of a nature similar
to those on the plateau east of Silver City occupy a similar topo-
graphic position and seem to show much the same history.

A good example, with which the writer is familiar, is the Bishop
conglomerate of southwestern Wyoming and northeastern Utah.
This represents a Piedmont gravel accumulation derived from the
Uinta Mountains, and at one time skirting entirely round their
base. Subsequent erosion has so lowered the mountains that over
considerable areas, particularly at the eastern end, they are actually
lower than the tops of the gravel-capped plateaus which represent
the eroded remnants of the Piedmont gravel deposits. This condi-
tion has been described by the writer in an earlier paper.t_ Between

«“The Physiography of the Bishop Conglomerate, Southwestern Wyoming,’
Jour. Geol., XVIII, No. 7 (1910), 601-32.

504 JOHN LYON RICH

the mountains and the plateau are valleys sometimes Io to 15 miles
wide, and as much as 2,500 ft. deep (zbid., p. 622). Other observers
who have worked on the soul side of the range report similar
conditions there.

The resistant qualities of the gravel are particularly well illus-
trated by the Bishop conglomerate. The plateaus have remained
with little change while general erosion has lowered the surround-
ing country nearly 1,000 ft. on the average.

In point of origin and later development, the Bishop conglomer-
ate is thought to represent exactly the same type of phenomenon
as we have described from the Silver City region; the only difference
being that, in the former case, the process has been carried farther
and the results are just so much the more striking.

CYCLE OF MOUNTAIN DEVELOPMENT

If the above analysis is correct, as it Seems to be, both from the
theoretical side and from field observation, the influence of gravel
deposits is an important factor to be considered in the cycle of
development of mountain topography. This-cycle is admittedly
complex, involving many factors, but for the purpose of clearly
presenting the point especially in mind at the present time, it is
not necessary to follow each of the factors involved. On the con-
trary, the consideration of the subject will be confined, as far as
practicable, to a brief outline of the manner in which gravels, by
reason of their selected nature, suffer less than other rocks.

At the initiation of the cycle of mountain development let us
postulate the following ideal conditions: A mountain range, or
simple fault block of moderately resistant and varied rocks sharply
uplifted above the surrounding country. Free drainage from the
foot of the mountains to some base level, either of interior or of
exterior drainage, lying at a considerably lower elevation. In
order to give the maximum of favorable conditions, we will postu-
late further that the climate is semi-arid so that vegetation plays
a subordinate role.

Granting these initial conditions, and assuming that there are
no further crustal movements, let us trace the development of
the mountain range.

GRAVEL AS A RESISTANT ROCK 505

At first, with steep, exposed slopes, disintegration, through frost
and insolation, and erosion will be rapid. The streams, while
powerful enough to carry the loosened material down the steep
slopes, will be unable to transport it across the lowland below.
Piedmont fans of coarse gravel will accumulate along the mountain
base. As time goes on the fans will continue to grow at the expense
of the mountains. During this stage the fans are the seat of con-
tinual deposition, the mountains of continual waste and removal.
Finally there must come a time when the mountains have become
so lowered that the streams are no longer flowing over steep slopes.
As this stage is approached, disintegration and decomposition
within the mountain area will become relatively more important
and the rocks will be reduced to a finer condition before being car-
ried off. The streams will no longer be overburdened with sediment
too coarse to be carried beyond the base of the mountain. At
‘this point the upbuilding of the fans at the immediate mountain
base must cease while the locus of deposition is shifted farther out
because the stream load, being of a finer nature, may be carried to
a greater distance before deposition occurs.

This is the turning-point in the history of the mountain range.
From now on, both mountains and fans will be subject to denuda-
tion or degradation. If both the fans and the mountains were
worn down at an equal rate, the whole area would merely lose in
elevation without any marked change in the relations of mountains
and gravels. Since, however, according to our thesis, the gravels
will suffer from erosion less than the rocks of the mountains,
differential erosion becomes an important factor. As the slopes
decrease and decomposition plays an increasingly important réle
while the material furnished to the streams becomes finer and less
in amount, the burden of the streams becomes less and they are
able to cut where deposition was in progress before, and will sink
their channels into the Piedmont fans.

Since the mountains are lowered faster than the gravels, a low-
land will gradually develop, beginning first near the position of the
inner margin of the gravel at the time of the change from aggrada-
tion to degradation. If the base level of the streams is sufficiently
low, this lowland may eventually come to include the whole of the

506 JOHN LYON RICH

mountain area. If the streams crossing the Piedmont gravel fans
sink deeply enough they may finally cut entirely through the gravel
into the underlying rock. In that case we will have a plateau
between the streams, capped by gravels of a composition corre-
sponding to that of the rocks of the lowland which occupies the site
of the original mountains, but lying at a level higher than the
summits of these mountains as they now exist.

Various combinations of factors will modify in different ways
the course of development as sketched above, but the general
principle involved should hold true, and the results should be in
harmony with this principle as modified by the particular factors
dominating in any one case.

EXAMPLES ILLUSTRATING THE TYPE OF DEVELOPMENT ABOVE
OUTLINED

As examples of the influence of the slower differential erosion
of gravel deposits the following may be mentioned: The region
east of Silver City; the Uinta Mountains and the associated Bishop
conglomerate, both described in the preceding pages. The Cats-
kill Mountains of New York, in their relation to the old lowland to
the east, are a possible illustration of the principle.

THE CRETACEOUS AND TERTIARY FORMATIONS OF
WESTERN NORTH DAKOTA AND EASTERN
MONTANA

A. G. LEONARD
State University of North Dakota

CONTENTS

INTRODUCTION
PIERRE SHALE

Distribution

Characteristics

Fossils

Yellowstone—Bowman County area

Dawson County area

Fox HILis SANDSTONE
Distribution
Cannon Ball River area
Contact with Lance formation
Little Beaver Creek area
Dawson County area
Variability of Fox Hills

LANCE FORMATION

Distribution

South-central North Dakota area
Section on Cannon Ball River
Section on Heart River
Bismarck section
Divisions of the Lance formation

Little Missouri area
Contact of Lance and Fox Hills
Plants
Oyster bed
Dinosaurs

Yellowstone Valley area
Glendive section
Fossils

Missouri Valley area
Section on Hell Creek
Fossils

Age and relationship of Lance formation

5°7

508 A. G. LEONARD

Fort UNION FORMATION
Character of the beds
Coal
Plants
Invertebrates
Vertebrates

WHITE RIVER BEDS
White Butte area
Little Bad Lands area
Sentinel Butte area
Long Pine Hills area

INTRODUCTION

The Cretaceous formations represented in the area under dis-
cussion are the Pierre shale and Fox Hills sandstone. Overlying
the latter is a non-marine formation, which has variously been
called ‘‘the Ceratops beds,” “‘Lower Fort Union,” ‘‘Somber beds,”’
‘““Laramie,”’ “Hell Creek beds,’ and °‘Lance formation.’’ (The
United States Geological Survey has recently adopted the name
“Lance formation,” derived from the term ‘Lance Creek beds,”
which was applied to the deposits by J. B. Hatcher, and this name
is employed in the following pages. The age of the Lance formation
is still unsettled, some geologists regarding it as part of the Fort
Union and thus early Eocene in age, while others believe that it
included, or is part of the Laramie and is, therefore, Cretaceous.
The Tertiary formations are represented by the Fort Union and
White River.

Western North Dakota is particularly favorable for the study
of these formations, since they are excellently exposed in the
Little Missouri badlands and along the valley of the Missouri
and its tributaries. Bowman and Billings counties afford a con-
tinuous section extending from the Pierre shale up through the
Fox Hills, Lance formation, and Fort Union to the White River
beds of the Oligocene, involving a thickness of some 2,150 feet of
strata.

The data here presented were gathered during seven seasons
of field work in North Dakota and Montana, a portion of the time
as assistant on the United States Geological Survey, and a portion

CRETACEOUS AND TERTIARY FORMATIONS 509

under the auspices of the North Dakota Geological Survey. The
work in Montana was confined mostly to Dawson and Custer
counties; the Yellowstone River having been followed from its
mouth to Miles City, and a trip being taken north from Miles City
to the Hell Creek region and across the Missouri River to Glasgow.

PIERRE SHALE

The Pierre shale is exposed along the Missouri River for a dis-
tance of about twenty miles north of the South Dakota line, or
as far as the mouth of Big Beaver Creek in Emmons County;
in eastern Montana it appears along the Missouri Valley from a
point probably as far west as the Musselshell River to the station
of Brockton, on the Great Northern railroad, or a distance of
nearly 180 miles; it also occupies a small area on Little Beaver
Creek in northwestern Bowman County, North Dakota, which is
probably continuous with the Pierre outcrop on the Yellowstone
River, twelve miles above Glendive.

The Pierre formation is a bluish gray to dark gray, sometimes
almost black, jointed shale, which often weathers into small,
flaky fragments. The rock commonly shows yellow spots or stains
of iron oxide. The topmost beds of the Pierre contain numerous
calcareous concretions varying in size from a few inches to six and
eight feet in diameter. Some of these concretions are rich in
invertebrates, which are characteristic of the upper forty or fifty
feet of the Pierre, while others are barren of fossils. Many are
cut by a network of calcite veins which are commonly lighter
colored than the matrix. The following species, identified by Dr.
T. W. Stanton, were collected in the Little Beaver Creek locality,
Bowman County, North Dakota:

Ostrea pellucida M. and H. Lunatia.

Avicula lingueformis E. and S. Anisomyon patelliformis M. and H.

Inoceramus cripsi var. barabini Mor- Margarita nebrascensis M. and H.
ton. Fasciolaria? (Cryptorhytis) flexi-

Chlamys nebrascensis M. and H. costata M. and H.

Yoldia evansi M. and H. Pyrifusus.

Nucula cancellata M. and H. Haminea ? occidentalis M. and H.

Lucina occidentalis Morton. - Scaphites nodosus Owen vars. brevis

Protocardia subquadrata E. and S. and plenus.

Callista deweyi M. and H. Nautilus dekayi Morton.

510 A. G. LEONARD

From the locality on the Yellowstone, at the mouth of Cedar
Creek, the following marine shells were secured, from the upper
fifty feet of the Pierre:

Avicula nebrascana M. and H. Scaphites nodosus Owen vars. brevis
Avicula linguaeformis E. and S. and plenus.
Inoceramus sagensis Owen. Limopsis parvula M. and H.
Inoceramus cripsi var. barabini Mor- Yoldia evansi M. and H.

ton. Lucina subundata M. and H.
Modiola meeki E. and S. Protocardia subquadrata E. and S.
Veniella subtumida M. and H. Dentalium gracile M. and H.
Callista deweyi M. and H. Vanikoro ambigua M. and H.
Anchura americana E. and S. Margarita nebrascensis M. and H.
Haminea occidentalis M. and H. Fasciolaria (Piestocheilus) culbert-
Pyrifusus newberryi M. and H. soni M. and H.
Lunatia concinna M. and H. Baculites ovatus Say.
Scaphites nodosus var. quadrangu- Nautilus dekayi Morton.

laris M. and H. Chlamys nebrascensis M. and H.

The beds which outcrop at the latter locality on the Yellow-
stone, twelve miles above Glendive, Montana, are brought above
river level by an anticlinal fold, the dip of the strata here being
20. S. 52° W. The Bowman County outcrop is probably caused
by the same anticline, since the strike of S. 38° E. shows that the
fold so well exposed on the Yellowstone, if continued in that direc-
tion, would include the Little Beaver Creek locality. That the
two areas of outcrop are continuous seems probable from the fact
that ammonites and other marine shells are reported to have
been found at several intervening points on Cabin and Cedar
creeks.

There are extensive outcrops of Pierre shale along the Missouri
River and its tributaries in the northeastern corner of Montana,
in Dawson and Valley counties. At the mouth of Big Dry Creek,
fifteen miles south of Glasgow, the shale rises 200 feet above the
river, and it is also well shown on most of the creeks entering the
Missouri from the south for a distance of eighty or one hundred
miles west of the Big Dry. Among these is Hell Creek, on which
150 feet of Pierre are exposed above creek level. Among the most
common fossils occurring in the calcareous concretions of this
locality are ammonites and baculites.

CRETACEOUS AND TERTIARY FORMATIONS 511

In the southeastern corner of Custer County, Montana, as a
result of the Black Hills uplift, the Pierre shale outcrops over an
area of considerable extent, overlying the Benton and Niobrara
formations, which also appear at the surface.

FOX HILLS SANDSTONE

The Fox Hills sandstone is the most recent of the marine for-
mations of the Great Plains region. It is very variable in character
and undergoes considerable change in composition and appearance
from one locality to another. It is exposed on the Missouri River
as far north as old Fort Rice, about eight miles above the mouth
of the Cannon Ball River; it appears on Little Beaver Creek, a
tributary of the Little Missouri in southwestern North Dakota;
on the Yellowstone a few miles above Glendive, Montana; it
occurs in the Hell Creek region, and also on the Missouri River,
near the town of Brockton, Montana.

On the lower Cannon Ball River, for a distance of ten or twelve
miles above its mouth, the Fox Hills formation is exceptionally
well shown. In many places it forms cliffs rising abruptly from —
the water’s edge, and the cuts made for the new branch line of the
Northern Pacific afford many excellent exposures. It rises eighty
to ninety feet above the Cannon Ball River, or approximately
1,080 feet above sea-level.

The Fox Hills sandstone when unweathered is gray with yellow
patches, but in weathered outcrops it is yellow or brown in color.
The rock is rather fine-grained and, for the most part, so soft and
friable that it can be.crumbled in the hand. Cross-bedding is
very common and the rock contains great numbers of large and
small ferruginous sandstone concretions or nodules, many of these
likewise exhibiting cross-bedding. The nodules are apparently
due to the segregation of the iron into irregular patches cementing
the sand into firm, hard masses, considerably harder than the
sandstone in which they are imbedded. In many places the iron
has impregnated certain layers and formed indurated ledges,
which resist weathering and project beyond the softer portions
(Fig. 1). The nodules vary in size from an inch and less to six
and eight feet. Small, irregular, twisted or stem-like forms are

512 A. G. LEONARD

abundant at certain points. Some portions of the rock are so
completely filled with these brown concretions that they constitute
the main bulk of the formation, and the gray, loosely cemented
sandstone forms a kind of matrix in which the hard nodules are
imbedded. In the process of weathering these more resistant
nodules project far beyond the softer rock, and at the base of slopes
and scattered over the surface they are exceedingly abundant.

Fic. 1.—The Fox Hills sandstone on Cannon Ball River, North Dakota, showing
hard ledges and concretions on a weathered surface.

Where the rock has only a few concretions, and therefore, where
the iron has not been segregated to as large an extent at certain
points, the sandstone is of a yellow color, due to the disseminated
iron oxide. On the other hand, where the brown ferruginous
nodules are thickly scattered through the beds, the rest of the rock
is gray, the iron having been largely leached from it and concen-
trated in the nodules. Many of the latter are of good size and
spherical in shape, and it is these which have given its name to the

CRETACEOUS AND TERTIARY FORMATIONS 513

Cannon Ball River, since they occur abundantly along that
stream.

The following Fox Hills fossils were collected on the Cannon
Ball River about ten miles above its mouth:'

Tancredia americana M. and H. Avicula nebrascana E. and S.
Callista deweyi M. and H. Protocardia subquadrata E. and S.
Tellina scitula M. and H. Mactra warrenana M. and H.
Ostrea pellucida M. and H. Mactra ? sp.

Avicula linguiformis E. and S. Scaphites cheyennensis (Owen).

The first three in the above list occurred in a bed of sandstone
forty feet below the top of the formation, while the others were
from a higher horizon, ten feet below the top of the Fox Hills.

About three miles below this locality specimens of Mactra
warrenana M. and H., Dentalium gracile M. and H.? and Cinulia
cincinna (M. and H.) ? were .collected.

On Long Lake Creek, a tributary of the Missouri River, from
the east the sandstone yielded the following: Avicula linguiformis
E. and S., Tellina scitula M. and H., and Chemnitzia cerithiformis
M. and H.?

The contact of the Fox Hills sandstone with the overlying
Lance formation is well shown in the bluffs on the north side of
the Cannon Ball River, about ten miles above its mouth. Here
the two formations are seen to be conformable, the top of the Fux
Hills being marked by a light gray, almost white sandstene, which
exhibits cross-bedding (Fig. 2). This bed is one foot to eighteen
inches thick. Sedimentation was apparently continuous from
Fox Hills time on into the period when the Lance beds were being
formed.

East of the Missouri River, in Emmons County, the sandstone
is present on Beaver Creek, extending up the valley of that stream
almost to Linton, and having an elevation of nearly 150 feet above
the creek, near its mouth.

About 160 miles west of the Missouri River, the Fox Hills
sandstone is exposed in a small area on Little Beaver Creek, in
the northwest corner of Bowman County, North Dakota. The
section here is as follows:

t Identified by Dr. T. W. Stanton.

514 A. G. LEONARD

Feet

Sandstone, massive, light greenish gray, weathers to yellow color...... 50

Sandstone ledge, yellow:..252 220 sss ees ane haus chaos Ue ates che 8-10
Clay, sandy, finely laminated and formed of alternating light and dark
laminae. Contains nodules of iron pyrites. Exposed above creek

Cig: RR Rae he ee RE Un enn ye RIM 5 linn agi am It Nenad a oe 25

In this upper sandstone, Dr. T. W. Stanton collected several
marine fossils characteristic of the Fox Hills, including Leda

Frc. 2.—The Fox Hills and Lance formations on the Cannon Ball River. The
contact is at the hard ledge on which the man is standing.

(Yoldia) evansi, Tellina scitula, Entalis? paupercula, and Haly-
menites major.

Where exposed in bluffs along Little Beaver Creek, at several
points the gray sandstone shows an uneven, eroded surface,
which the writer has described as an unconformity.*. It may,
however, be due to the action of currents in the shallow sea of
Fox Hills time, as suggested by Dr. Stanton, in which case no long

t Fifth Biennial Report, N.D. Geol. Surv., 44.

CRETACEOUS AND TERTIARY FORMATIONS 515

time interval between the deposition of the sandstone and the
overlying Lance beds would be indicated by the eroded surface
of the Fox Hills. .

In the vicinity of Iron Bluffs, on the Yellowstone twelve miles
southwest of Glendive, Montana, the Pierre is overlain by 150 feet
of sandstones and shales, the age of which is in doubt, though the
beds have the stratigraphic position of the Fox Hills. The lower
seventy-five feet is composed of shales and sandstones while the
upper half is formed of a brownish sandstone. The only fossils
found in these beds at this locality are some plants, which are
too fragmentary to be identified.

The Fox Hills sandstone is well exposed on Hell Creek, a trib-
utary of the Missouri River in northwestern Dawson County,
Montana. Lying above the dark gray Pierre shale, with its
fossiliferous concretions, are 1oo feet of shales and sandstone
belonging to the Fox Hills. The formation is here composed of
light gray to yellow, more or less sandy shale, with some layers
of nearly pure sandstone. About eight feet below the top, there
is quite a persistent bed of fine-grained yellow sandstone with a
thickness of eleven feet (Fig. 3). The beds are lighter in color
and, for the most part, more sandy than the Pierre shale. From
concretions near the summit of the Fox Hills on Hell Creek, Mr.
Barnum Brown collected the following shells :*

Cardium (Protocardium) subquad- lLunatia concinna M. and H.

ratum E. and S. Cylichna scitula? H. and M.
Nucula cancellata M. and H. Baculites ovatus Say.
Tellina scitula M. and H. Scaphites conradi Morton.
Yoldia evansi M. and H. Chemnitzia cerithiformis M. and H.
Crenella elegantula M. and H. Mactra? nitidula M. and H.
Piestochilus culbertsoni M. and H. Actaeon (Oligoptycha) concinnus M.
Anchura (Drepanochilus) americana and H.
513; BNC!

Along the Missouri River valley, over too miles northeast of
Hell Creek, and near the station of Brockton, on the Great Northern
Railroad yellow sandstones interstratified with gray clay are found
overlying the Pierre.?, These beds are probably to be referred to

t Bull. Am. Mus. Nat. Hist., XXIII, 827.

2 Carl D. Smith, Bull. U.S. Geol. Surv., No. 381, 38.

516 A. G. LEONARD

the Fox Hills formation. Their thickness is about 200 feet and
they are well exposed in the river bluff south of Brockton. Asa
rule the sandstone is soft, but in places there are hard concretion-
like masses, which after weathering stand out as ledges or as
cannon-ball shaped masses imbedded in a matrix of softer rock.
The material shows much irregularity of bedding, is in places
cross-bedded, and is extremely variable in character horizontally.

Fic. 3.—The Fox Hills formatioa on Hell Creek, Moatana, showing sandstone
ledge (A) near the top.

The Fox Hills sandstone probably occurs also about the Pierre
shale area in southeastern Custer County, Montana.

The variability of the Fox Hills formation is well illustrated by
the foregoing description of its outcrops. In some places, it is
composed wholly of sandstone, in others it is mostly a sandy shale,
while in still others it is partly sandstone and partly shale. When
shales are present they are generally arenaceous and are commonly

CRETACEOUS AND TERTIARY FORMATIONS ley

most abundant toward the base of the formation, where, in some
places, they pass gradually into the Pierre shale. It will be seen
from the above lists that some of the fossils occurring in the upper
part of the Pierre range up into the Fox Hills. The top of the latter
is better defined than its base, the change from it to the overlying
Lance beds in some places being abrupt, but generally the two are
conformable. The Fox Hills beds vary in thickness from seventy-
five to two hundred feet.

LANCE FORMATION

The Lance beds have a wide distribution in North Dakota and
eastern Montana, as well as in northwestern South Dakota and
northeastern Wyoming. The largest area in North Dakota is
in the south-central part of the state, where this formation occupies
a large part of Morton county and all of the Standing Rock Indian
Reservation, outside the Fox Hills and Pierre outcrops; east
of the Missouri River, it covers southern Burleigh and the greater
part of Emmons County, together with adjoining portions of
Kidder, Logan, and McIntosh counties. In the southwestern
corner of North Dakota is a second smaller area stretching along
the Little Missouri River for a distance of over fifty miles in western
Bowman and southern Billings counties. In eastern Montana
the Lance beds are found along the Yellowstone River from the
vicinity of Forsyth to a point about fifteen miles below Glendive.
South of the Yellowstone, these beds are exposed along the valleys
of the Powder and Tongue rivers and their tributaries. The
badlands occupying a wide strip of country on the south side of
the Missouri River in northern Dawson County are for the most
part formed of Lance beds, and they extend as far east as Brockton.
According to C. D. Smith™ the formation is found on the Fort
Peck Indian Reservation, and the beds also occur west and north
of the reservation in Valley County, Montana.

South-central North Dakota area.—In Morton County, North
Dakota, numerous good outcrops of the Lance formation appear
along the Missouri, Cannon Ball, and Heart rivers and many of
the smaller streams (Fig. 4). The beds are found along the Mis-

t Bull. U.S. Geol. Surv., No. 381, 39.

518 A. G. LEONARD

souri River to within eight or ten miles of Washburn, where they
disappear below river level and are replaced by the Fort Union.
On the North Fork of the Cannon Ball they extend almost as far
west as the Hettinger County line, and on the Heart River they
reach to within a few miles of the Stark County line. Along the
boundary between North and South Dakota the western border

Fic. 4.—Bluff of Missouri River near old Fort Rice, showing the lower Lance
formation.

of the formation is not far from Haynes, on the Chicago, Milwaukee
and Puget Sound Railroad.

In passing down the North Fork of the Cannon Ball River
from the western edge of Morton County to the junction with the
South Fork, and thence down the Cannon Ball River to its mouth,
one traverses the entire thickness of the Lance formation from the
Fort Union above to the Fox Hills below. About ten miles below
the Hettinger County line; inisec. 5, (eiasey Nee Ren com\Venmtne

CRETACEOUS AND TERTIARY FORMATIONS 519

contact of the Fort Union and Lance beds is well shown in the

following section, exposed in a high bluff of the river:
Feet Inches

15. Shale, light gray and yellow, to top of bluff......... beens ta 16
AROMA CHOCOlatE DOW an choi hers We cessive ais aie spe be ele I 6
RE SUAS, INVENT Facey se aOR ee Re 6
12. Shale, light yellow, soft, and readily crumbled............... 6
TER 5. UME, WEA aE rg UR a CE 15
HO, (COM. s 5, grasa ese Ais eck oe ecu ea Er eae 4 2
Oo SMG, CAPS Seg coe cic aaa eC EOL Re a a eae a 23
Bo (COfilly 5 6 bed Bie Sie SBN Abts See tae ee Sire Oa 2
FEMS Welle ate args ee as Tice TRIG, 6 caus arasei ns wn ¥ aches aieue, coe I 6
Ga C Oa nnn pr crm Mir Men NU reine SMe tl Do, Mia edie nid’ lulls Bb arail Bi
FeAl sanyo Mtoe raya was. Aas sce cece Wed Slehaey aang wee Slew ike)
Amma (© ©) ci see oso ER Sas sevens Gran. Salles or ocen 0 Hie de I 6
Beroanestonesuehtvorayicross-bedded...2..:....2.65s6 540200: 25
Paonalewsandy sorOwi. with MUCAMTOM, 2.05 ..0. 00.500. 6. 000 er 4-6
1. Sandstone, soft, yellow, with concretions and some thin limoni-
HICEStheakcuexpOsedsaMOve MIVEES 2am 4 dasa. sce agen. 50
163 9

Nos. 1, 2, and 3 of the above section belong to the Lance for-
mation, while the other members are Fort Union. As is the case
at a number of points, a coal bed (No. 4) occurs at the contact,
and there are also two workable beds above this. The upper
sandstone of the Lance formation extends down the river seven
or eight miles below this section, forming in many places vertical
cliffs rising from the water’s edge. Then a dark shale appears
beneath the sandstone as shown in the following section, which
is seen about ten miles below the previous one, in secs. 29 and
Bon 23Ne Re 83) W-:

Feet
Koa ndstonesottsvellowsitontopror blithe is. tee. aS nae hk eee 20
4. Shale, dark gray to black, alternating with thin-bedded, shaly sand-
SEO TV Cree eric See Mee a rear ta ned as ia AI Socal cy Rial a al shasta vant ins rants yelianegele I5
Bennalewdarksoray toublack. when Mmoist,.:.4. 92-206. 6222. ss ee els 70
PeSandstones yellows wathehard ledge neat top... .W.c-css. cs 4500s ee oe 20
1. Shale, dark gray to black, sandy, exposed above river................ 25
150

Only twenty feet of the upper sandstone of the Lance formation
appear at this point, and the bluffs are here formed largely of the
underlying black shale.

520 A. G. LEONARD

The beds near the middle portion of the Lance formation are well
exposed in the bluffs on the south side of the Cannon Ball River
near Shields where the following section occurs:

Feet Inches

Soil and subsoil: 23. sen ees iis ee oe one ee rs 4-5
Sandstone, yellow to gray. soft and friable... ..:.. 25... 31
Shaleveray amd) yell owe en iene ececrenpe oe) ie tem ee yee eect? ie)
Sandstone, gray and yellow, containing thin shale layers and

brown, carbonaceous: streaks 0%).3) otc ss Meee 38
Shale, gray, contaminguiron COncretions. 8 9... Gece ciat ce pels 6
Shale, black and brown, carbonaceous; containing dark brown

fEFRUMINOUS*COMCKELIONS: 20) le sess ss Geese ee 6-10
Shales gray = cuts Me ram acter eter ee eer eee 15 6
Shale-brown, carbonaceous tinct at se tate ta canes east I
Ghale,jeraly sarily sect. ei na etc Greta ae al eae ye 3
Shale: brown, carbonaceous.) viet vec a. ein gilts eign ane ge te 18
Cae ee ee eats etre fe aeoalee catoetul St ar elimi Tn UCR iy La cc eae ae 6
Shalewblackscoallivic en sac teen ete sO Uae mes et eens I 4
Shalesrorarya Samclyse, tease tte tas Sc tele ton anaes ce geen ee a Bees II
Shales brow Cat bOnaceOUsi.a Miva ec) scks cr eae ae I 6
Shale every, SAMGy cass es che vie tcc Gegupntere) acta aha eon cement I 6
Shale “browimncarbonace Osis!) ss s.cec het cene ere weenie eee 2 6
Ghia Fesigrreh yoeeee icant Cue ae tea et notes cutie Inked get ern a a le metre eae etc ae 7 6

Sandstone, gray, soft, with shale layer near middle, 2-4 feet

(oN (el ey ORM Ea ROME RAD Siena MLL one UME cAtn on UI earn aitabte Ale ato 44
Glyale sera: cue eas cetceteres ay ae alc ie ate di ae ge eee ees 8
We xpOSCCs LO MIVEL, tetas ore we ee uthrenen eect ee eee eee 20

Bo) 22° Up vere vene ee LOM et ca eR oria eens OE, AI nV ORNA aida oMint ce 210

One of the characteristics of the Lance beds, exhibited in many
widely scattered localities, is well shown in this section; namely,
the many brown, carbonaceous layers which are present, often
forming a conspicuous feature of the formation, as along the Little
Missouri River. It will be noted that the beds are here composed
about evenly of shales and sandstones, though the latter are con-
fined to three thick members. .

About thirty miles below Shields, and ten or twelve miles
above the mouth of the Cannon Ball, the lower Lance beds are
exposed, together with the underlying Fox Hills sandstone, as shown
in the following section:

CRETACEOUS AND TERTIARY FORMATIONS 521

eet
AD atisCpoTaye aT ySam asic pees cea ceayaiene ee aasuck geile i TANI Ree Bin eee 2
Sinaleteclania colored ere treeg ccs eter aie SN dns. OM el na moe ewe Melee ae 27
Sandstone, soft, with many thin, brown, carbonaceous laminae......... 11
SAMAS LOM CMe IO WARSONE us Seat che ane Tw inaee at Sy Sh eee 16
Shale, brown, carbonaceous, with two coal seams, one 3 inches and the
CRM che mil CMes mtn Chon Peet ya nM sm ht gr. cia tate ath Gace seh gee may 8
SIMBUG, CARBINYc: : 3.88 dso fate tne OY ae RLY Te ae 3
SAINGISTHOMNG STEN Le 5 Ooi lees eR eg Se RRR eee a ea eG 8
SIMGIKS, PAREN 6a 5 eR coc aN sea ese er Soc are ie a ree gO 4
Shale wkOwlrCa TD OMACeOUSsai ieee icseeye wuss ae sig Hees in eel eke: 3
Sandstone and shale in alternating layers, the former predominating;
colorsadarkyerayeeprown, andeyellow? 2.5. .<..2 +4 lotsa oe dee Sa
Shalesidarkerave witha few, browm bands... ..0:.0......¢c.1.s. ss eu: 22
Sana scome re NO xg elt ll Semon erence Ate ae tl iat ox. ule sctcte Manele thins 80
TROLL ga ec seth ea eae Nr Oe eg ER gt LA 241

From the lower sandstone of this section, Fox Hills shells were
collected. The Lance beds here rest conformably on this sandstone,
and there appears to have been a gradual change from the marine
conditions of Fox Hills time to the fresh-water conditions under
which the Lance beds accumulated, with continuous deposition
throughout.

The strata forming the upper 350 feet of the Lance formation,
comprising the upper, massive sandstone, and the underlying
dark shales, are very well exposed in the valley of the Heart River,
in Morton County. For a distance of five or six miles below the
bridge on the Glen Ullin—Leipzig road, this valley is a narrow
gorge walled in by sandstone cliffs. This rock, which forms the
upper member of the Lance formation, is-a massive, gray, brown,
and yellow sandstone, having a thickness of approximately one
hundred feet. The underlying shales are dark gray to black,
when moist, and weather to a yellow color. They are cut by
several sets of joint cracks and along these cracks the change
from gray to yellow first takes place, the gray, unweathered material
being left in the areas inclosed by the joints. Near the surface
the shales are weathered and oxidized throughout, but at some
depth the yellow color is confined to narrow bands on either side

522 A.G. LEONARD

of the joint cracks. In places, these beds are composed of thin
layers of black shale and gray, very sandy shale, or sand.

On the Heart River, south of Almont, the following section
appears, embracing portions of both the Lance and Fort Union
formations:

Feet
5) ‘Sandstone; yellow, Soft, massive a9. ter nen or eee errs ete eee 50
a. Shales yellowandélight gray <4 sso we es ea ete a ee 61
gt Sandstone x white ales © sts, sista ease oe ceo tne cere ae a hs ee ee 30
2. Sandstone, yellow and brown below, gray toward top. The upper
sandstone.ot the Wancetormatione: .1c,s5 ener) eee eee ee 95
tShales. darkccolored es eerie ata etic ane ot tern ate ayant eee 180
416

Nos. 1 and 2 belong to the Lance formation, while the three
upper numbers are Fort Union. On the Heart River in the vicinity
of Mandan and in the bluffs of the Missouri near Bismarck, the
Lance beds are made up chiefly of the dark shales, as is evident
from the two sections which follow. The first is exposed at the
east end of the Northern Pacific railroad bridge over the Missouri
River.

Feet Inches
Drift, resting on the eroded surface of the Lance formation. .... 15-20
Shale, dark gray to black, with thin, light gray streaks; cut by
many joint cracks several inches apart. Faces of the joints
StaimedsbyiPONk o0s.uc cecrti taeie aoe ease eee ne ie 42
Shales sandy blackcams tits atone: che vena tc aes beeen iio ie Cree I
Slialles Polack oes 08 Ws SAE anda eee ayens ite tare adam in tog ua ers 3 6
Sandstone darkieray toiblack ye. anne valence ei ce seeks stellen i
Shales Polack & aioe seh 0) ue haart Sy ine are fare eotea eae neaine tat on ost eS 2 6
Sandstone vello we): y5 cece sheers Sev cso mcrae ee eee eee eae 4
Shale, dark gray to black, alternating with yellow, fine-grained
sandstone-and! sandy shaleacia 672, aeoem te ces ee tine 22
Slate: Polack es es Le ae NY rec Mee tack Uda nada stay 30
Umexposeditomiviersle vel seis ae ete ie se ae ease ei Seca ae 15
MO CAN Sh sche kG Pe Sel Ne Sine Mea: ane PAU i ng ON ee I4I

The second section appears on the south side of the Heart
River two miles above Mandan, and is as follows:

CRETACEOUS AND TERTIARY FORMATIONS 523

SOilPS an Cliygmarmery rere ts Cr fe ae al Rei el aa Me ee ee 3

Scams CISTOCE Me mpstenetn tise irate Rey tata Gt Mat) ah adele a eetet spent 20

Shale, gray and black, mottled; arenaceous in part, the sand
being very fine; sandy layers have yellow color. Some por-
tions contain considerable carbonaceous material, which
gives the rock its black color. Shale cut by several sets of
joints running irregularly in many directions, but all making
large angle with the horizontal. These joint cracks are filled
with gypsum and the sides stained with iron. The mottled
character shows on weathered face of the bluff, where there

are large blotches of black on the gray surface............ 28
Shale, dark gray and yellow, some layers sandy; more thinly

peddedkthanioverlyingimemlber. fyi. pels. ee eal. ee oe 7 6
Sandstone, soft, fine-grained, gray, and yellow................ 7 6
Sandstone, argillaceous, forming hard projecting ledge........ 2
Shale, dark gray to black, alternating with bands of laminated,

AIM e=- ST AINE HClO wWeSAMGe cay, eset chet le rie es aba hese nals as 3
Shalerdarkveray to blacks whenmnoist <).%. 206). 000s ons sews ) 6
Sandstone’ soft and incoherent, yellow... .29.505.......5..04 I
Winexposeditopriviermevielim artic etn Ne aac cis mane stalls an 3 27

eS
°
=
i)
He
4
e)
oO
oO

In the vicinity of Long Lake, in southeastern Burleigh County,
and in the railroad cuts along the Linton Branch of the Northern
Pacific, in northern Emmons County, the sandstone and shales
of the Lance formation are well exposed, and they outcrop at a
‘number of points about Linton. The eastern boundary can be
determined only approximately on account of the heavy mantle
of drift, which covers the bed-rock.

The Lance formation of south-central North Dakota, as shown
on the foregoing pages, consists of three members: an upper sand-
stone about one hundred feet thick, a middle member composed
of dark shales with a few sandstone layers and having a thickness
of 200 to 250 feet, and a lower member made up of shales and sand-
stone in alternating layers. This latter member has a thickness
of 350 feet or over, and the maximum thickness of the entire Lance
formation is probably not far from 700 feet in this region.

Fossils occur sparingly in this area. <A portion of the tibia of

524 A. G. LEONARD

Triceratops’! was found at a horizon about 150 feet above the
Fox Hills sandstone, and in 1908 Dr. T. W. Stanton collected
dinosaur bones a few miles north of the mouth of the Cannon Ball
River. These were identified as Ceratopsia and Trachodon, and
came from beds approximately too feet above the Fox Hills sand-
stone.’

Fic. 5.—The Lance beds exposed in bluff of Little Missouri River near mouth
of Bacon Creek, Billings County, North Dakota. Shows many concretions.

Litile Missouri area.—Along the Little Missouri River in the
extreme southwestern corner of North Dakota the Lance Beds are
excellently shown in the bluffs and badlands bordering the valley.
In going down the valley from Marmarth to Yule, many good
outcrops appear and one passes from near the base to the top of
the formation (Fig. 5). It is seen to be composed mostly of alter-
nating beds of shale and soft sandstone, which have a notably
dark and somber aspect in marked contrast to the yellow and light
gray colors of the overlying Fort Union. The prevailing color

t Tdentified by Mr. C. W. Gilmore.
2 Proc. Wash. Acad. Sci., XI, No. 3 (1909), 250.

CRETACEOUS AND TERTIARY FORMATIONS 525

is dark gray, but weathered surfaces, especially when moist, fre-
quently have a greenish gray or olive color. Beds of brown,
carbonaceous clay shale are very common and conspicuous. The
strata also contain much dark brown, ferruginous material, occur-
ring both in thin seams and concretions, the latter being most
numerous at certain horizons, and fragments of these cover the
slopes in many places. Great numbers of sandstone concretions
are present, some small, and others eight or ten feet in diameter.

Only thin beds of coal, not over eighteen inches thick or less,
occur in the lower 300 feet or more of the Lance formation. Thus,
in the 250 feet of strata exposed at the mouth of Bacon Creek
there is practically no coal, the thickest bed being fifteen inches,
and the same is true for all the Lance shales and sandstones exposed
along the Little Missouri from the Pretty Buttes, five miles below
Marmarth, to the South Dakota line. But in the upper portion
of the formation, thick beds of lignite are found in many places.
In the vicinity of Yule, five or six coal beds are present in the upper
part of the member, and the coal of Bacon and Coyote creeks
occurs at about the same horizon.

The basal beds of the Lance formation, together with the
underlying Fox Hills sandstone, are well exposed on Little Beaver
Creek, several miles southwest of Marmarth, and the relation of
the two has already been described in connection with the Fox Hills.

The massive sandstone forming the top of the latter is seen to
have undergone erosion before the deposition of the very carbona-
ceous and argillaceous, brown and black sandstone, which shows
cross-lamination. Some of the depressions have been eroded to
a depth of six feet below the adjoining elevations (Fig. 6).

The uneven surface of the Fox Hills shown here is perhaps
due to contemporaneous erosion, and practically continuous
deposition may be represented in this locality, as on the Cannon
Ball River. The thickness of the Lance beds in southwestern
North Dakota is approximately 600 feet. It is not possible here
to divide them into three members, since the upper sandstone
and the middle shale member are absent, and the strata are com-
posed throughout of rapidly alternating shales and sandstones.

Plant remains are by no means as abundant in the Lance for-

526 A. G. LEONARD

mation as in the Fort Union, and in most localities they are quite
rare. The following species were collected in the upper portion
of the Lance beds near Yule?

Taxodium occidentale Newb. Sapindus affinis Newb.

Populus amblyrhyncha Ward. Viburnum Whymperi Heer.
Platanus Haydenii Newb. Trapa microphylla Lesq. of Ward.
Juglans rugosa? Lesq. Cocculus Haydenianus Ward.

Hicoria antiquora (Newb.) Kn.

Fic. 6.—The eroded surface of the Fox Hills sandstone overlain by dark, car-
bonaceous beds of the Lance formation. Little Beaver Creek, Bowman County,
North Dakota.

According to Dr. Knowlton, these plants belong without ques-
tion to a Fort Union flora. Near the mouth of Bacon Creek in
the lower part of the Lance formation and associated with the
dinosaur bones, a Ficus fruit was found. The same species is
present in the beds on Hell Creek and at Forsyth, Montana.

Five miles southwest of Yule, in section 16, T. 135 N., R. 105 W.,
an oyster bed was found in the summer of 1907. It was about
180 feet above river level or some 500 feet above the base of the
formation and most of the shells were near the middle of a layer
of brown carbonaceous shale seven feet thick, with a coal bed

t Identified by Dr. F. H. Knowlton.

CRETACEOUS AND TERTIARY FORMATIONS 527

below and another above. A band six to eight inches thick is
in places closely packed with the shells, which Dr. T. W. Stanton,
who visited the locality in the summer of 19090, refers to Ostrea
subtrigonalis and Ostrea glabra. While in the Little Beaver Creek
region there was an abrupt change at the close of Fox Hills time
from marine to land or fresh-water deposits, as Dr. Stanton points
out, this oyster bed is evidence that in this neighboring area
marine or at least brackish water conditions continued for some time after
non-marine deposition began. .... Such an oyster bed must have been
formed in tidal waters connected with the sea, and its presence here argues
strongly for the assumption that the underlying portion of the Lance forma-
tion was formed near sea level so that a slight downward movement permitted
temporary admission of brackish water into the low lying swamps and marshes
in which coal was forming. It is, therefore, most probable that the abrupt
change from marine to fresh-water and land conditions seen near Marmarth
is purely local, and that the eroded surface at the top of the Fox Hills does
not represent a time interval of any geologic importance.*

The lower portion of the Lance formation contains many
dinosaur bones among which those of Triceratops are most abun-
dant. Many were found in the badlands at the mouth of Bacon
Creek. Mr. Gilmore, who examined them, referred some tenta-
tively to the species Triceratops horridus (?) and one belonged
to the genus Trachodon.

Yellowstone Valley area.—The Lance beds, as already stated,
are found along the valley of the Yellowstone for a distance of
nearly 150 miles, or from the vicinity of Forsyth to a point about
fifteen miles below Glendive. They are well exposed near the latter
town, and in the vicinity of Iron Bluff, about ten miles southwest,
the following section occurs:

Sea Coalebed= burned wbue probably 6 feet thick! 45.7... .) 9). -.60.e ene:
7. Shale with a few thin beds of sandstone; one of these sandstone layers

Feet

2Zoneet above.the base contains many plants... 24.0.5). 0/9... 150
OMOANGS CONE MIMASSIVEROTAY.: csclhs Lier a ieinessre neds atte ahle joes Beets Se 40
5, shale and sandstone; a few fossil plants at base.................... 160
4. Sandstone, massive, white; most prominent stratum in the region.... 35
Bq.sandstones brown, forms summit of Iron Bluff; .705.....4......... 75
DES Al CeaTCUSaMaStOMer: ra. ete crn fn wie ea weed onion A as ol ee aos 75
1. Shale, dark, with calcareous concretions carrying abundant marine

Shellsi(Bierre); exposed to niverlevell.. 0230. 2. 2 sinc lf outa nceess 100

TROL Stine Lo ce ai See no RRS Cher MAE eS 635

t Am. Jour. Sci., SXX (September, 1910), 183.

528 A. G. LEONARD

The succession of strata in the above section is unlike that of
any other found in eastern Montana or North Dakota, which
includes the beds from the Pierre to the Fort Union, in that the
Fox Hills appears to be missing. At least, no invertebrates have
been found in Nos. 2 and 3, and the plants are too fragmentary
to be determined, so that the age of these 150 feet of sandstone
and shale overlying the Pierre is in doubt. They have the strati-
graphic position of the Fox Hills, but in the absence of Fox Hills
fossils it is perhaps best to include them provisionally with the
Lance formation.

In the white sandstone (No. 4) Dr. A. C. Peale collected the
following plants:

Populus cuneata Newb. Lauraceous leaf.

Ginkgo adiantoides (Unger) Heer. Ficus or Sapindus sp.
Quercus sp. Viburnum sp.

Ficus trinervis Kn. Viburnum whymperi Heer.

In the vicinity of Glendive, Barnum Brown records having
found fragments of Triceratops and Trachodont dinosaurs.?

At Miles City, the Lance formation rises 500 feet above the
Yellowstone River and in Signal Butte and the Pine Hills, several
miles east of town it is overlain by 200 feet and more of Fort
Union shales and sandstones. In this region, as elsewhere, the
prevailing color of the Lance beds is dark gray, and they present
the usual contrast to the light yellow and ash gray of the Fort
Union. The formation here contains several workable coal beds
which supply coal to Miles City.

The following plants were obtained from the Lance formation
in the bluffs of the Yellowstone across from Miles City at an
elevation of from 115 to 125 feet above the river:3

Populus cuneata Newb. Cornus Newberryi Hollick.

Populus amblyrhyncha Ward. Nelumbo n. sp.

Populus nervosa elongata Newb. Onoclea sensibilis fossilis Newb.
Populus rotundifolia Newb. Trapa? microphylla Lesq., as iden-
Corylus americana Walter. tified by Ward.

Hicoria ? sp. Corylus rostrata Aiton.

Platanus sp.
' Bull. Am. Mus. Nat. Hist., XXIII (1907), 823.
2 Proc. Wash. Acad. Sci., XI, No. 3, p. 197.
3 Identified by Dr. F. H. Knowlton.

CRETACEOUS AND TERTIARY FORMATIONS 529

_ A large number of plants collected from the same formation
in the Miles City region are listed by Dr. Knowlton in his discus-
sion of this area."

The Lance beds extend up the Tongue river about 50 miles
above its mouth, or to within about ten miles of Ashland.?

That they extend up the Powder River at least twelve miles
above Hackett is indicated by the finding of part of a Triceratops
skeleton at that point by Barnum Brown, the bones occurring
in dark shale near river level.s There is also evidence for believing
that the Lance formation appears along the Powder River valley
almost if not quite as far south as the Wyoming line, Mr. E. S.
Riggs, of the Field Museum of Natural History, having found on
the East Fork of the Little Powder River ‘‘a weathered skeleton
of Trachodon, partial skulls of Ceratopsia and fragments of a
large carnivorous dinosaur, probably a Tyrannosaurus. The
formation was thence traced along the east bank of Powder River
from Powderville to a point on Sheep Creek some miles northeast
of Mizpah.’’4

Missourt Valley area.—In Dawson and Valley counties, Mon-
tana, the Lance formation is exposed over a large area, bordering
the Missouri River from the Musselshell on the west to the station
of Brockton on the east. The beds are particularly well shown
in the badlands formed by the many tributaries of the Missouri
from the south. Among these is Hell Creek, which enters the river
south and west of Glasgow, and the formations occurring in this
vicinity have been studied and described by Mr. Barnum Brown.’
A massive brown sandstone here forms the basal member of the
Lance formation, whereas in south-central North Dakota it is
the upper member which is sandstone. The thick black shale
member is also absent, but in general there is a strong resemblance
between the beds of the two localities.

t Proc. Wash. Acad. Sci., XI, No. 3 (1909), 188-90. .

2C. H. Wegemann, ‘‘ Notes on the Coals of the Custer National Forest, Mon-
tana,” Bull. U.S. Geol. Surv., No. 381 (1909), 104.

3 Bull. Am. Mus. Nat. Hist., XXIII (1907), 823.

4 Proc. Wash. Acad. Sci., XI, No. 3 (1909), 204.

5 Bull. Am. Mus. Nat. Hist., XXIII (1907), 823-45.

530 A. G. LEONARD

The following section is exposed in the valley of Hell Creek:

7, Shale and sandstone, light gray and yellow, containing beds of coal es
2 to 11 feet thick, and also many plant remains. Fort Union... LES
6. Shale and sandstone, similar in appearance to No. 4, but contains
no dinosaur bonesec.s 3c... satel ees eo ae ne a ena 100
5. Coal bed, persistent, has been traced a distance of 25 miles........ 6

4. Shale and sandstone with prevailing dark gray color; contains

many brown, carbonaceous layers and some beds of coal. Con-

tained in this member are two fairly persistent sandstone horizons

from 15 to 20 feet thick, and with 30 to 4o feet of shale

between. These sandstones contain many large brown sand-

StOME: CONCKELTOTISE ane ven + heats Han ia Ane tae ee pare nee 210-260
3. Sandstone, the basal member of the Lance formation. Coarse-

grained and rather soft; characterized by its massiveness, irreg-

ularity of bedding, the great number of large sandstone concre-

tions, and its cross-lamination. Yellow and brown in color .... 100
2. Shale, more or less sandy, with some sandstone, light gray to buff.

Pox 55 tec 385) eh ce Seti ets fea oc getege os ee ng 100
1. Shale, dark gray, with fossiliferous calcareous concretions near the

tops Pierre Exposedeabovercreeke. ice a ar een eee 150

Nos. 3 and 4 of the above section, which belong to the Lance
formation, have yielded many dinosaur bones, including Tricera-
tops, Trachodon, and Tyrannosaurus; also the remains of Campso-
saurus, crocodiles, and turtles, together with a few mammal teeth.
Plant remains are rare in this region, but Mr. Brown found the
following associated with the skeleton of a dinosaur:

Sequoia Nordenskioldi Heer. Populus amblyrhyncha Ward.
Taxodium occidentale Newb. Quercus sp.

Ginkgo adiantoidis (Ung.) Heer. Ficus artocarpoides Lesq.
Populus cuneata Newb. Sapindus affinis Newb.

A large number of invertebrates were also secured from the
Lance beds, including many species of Unios.

The age of No. 6 of the above section, which corresponds to
Barnum Brown’s ‘“‘lignite beds,” is uncertain since it contains
almost no fossils. Largely on the basis of the lack of dinosaur
bones in this member, Mr. Brown separates it from his Hell Creek
beds and regards it as probably Fort Union. He correlates it,
however, and correctly, with the 4oo feet of strata exposed at

t Proc. Wash. Acad. Sci., XI, No. 3, p. 185.

CRETACEOUS AND TERTIARY FORMATIONS 531

Miles City, and it is known that these belong to the Lance for-
mation. The beds of No. 6 also contain the many brown, car-
bonaceous layers, so characteristic of the Lance formation in many
localities, as well as a number of coal beds, which are also found in
that formation in certain areas, as already shown. There would
seem to be seme ground, therefore, for including this member
with the underlying Lance beds rather than with the typical

Fic. 7.—The Fox Hills (A) and Lance (B) formations exposed on Hell Creek,
Montana.

Fort Union, to which it bears little resemblance. If so included
the Lance formation in this region would have a thickness of about
400 feet. According to Brown there is an unconformity at its
base, which shows near the Cook ranch on Crooked Creek, and also-
on Hell Creek. Neither of these points was visited by the writer,
and where the top of the Fox Hills was seen no evidence of a
long erosion interval was observed, though such may be present
in the localities above mentioned (Fig. 7).

The Lance formation appears to grow thinner toward the north-

532 A. G. LEONARD

east, since on the Fort Peck Indian Reservation, according to C. D.
Smith, ‘‘about 200 feet of somber-colored sands and clays, with
numerous carbonaceous layers and a few beds of impure lignite,
overlie the Fox Hills sandstone.’* In that region there is no
apparent unconformity between the Fox Hills and the Lance
beds, the two so grading into each other that their contact is very
indefinite. Good exposures of the latter formation are found
on Cottonwood Creek and Poplar River in the Fort Peck
Indian Reservation, and in the badlands south of the Missouri
River.

The Lance formation lies near the boundary line between the
Cretaceous and Tertiary, and for this reason it is difficult to
determine to which of these systems it should be referred. In
most places where the contact has been observed it is seen to rest
conformably on the Fox Hills sandstone, and everywhere passes
conformably into the Fort Union above. Deposition was thus
continuous from Cretaceous time on into the Tertiary, and there
is no break in the sedimentation which might form a line of separa-
tion. On stratigraphic grounds, therefore, the Lance formation
is as closely related to the Fox Hills sandstone below as to the Fort
Union above, and we are forced to depend on the fauna and flora
for the determination of the age.

According to Dr. Knowlton, 193 forms of plants have been
found in these beds and of these, 84 species have been positively
identified. Since the greater number of these plants (68 species)
are common to the Fort Union, he considers the Lance beds the lower
member of the Fort Union formation, and, therefore, of Tertiary
age. The writer formerly held the same opinion regarding the age
of the Lance formation, but on the basis of its vertebrate fauna,
including many dinosaurs, and its conformity with the underlying
Fox Hills, there is much ground for the belief held by Dr. Stanton
and others that the Lance beds should be regarded as of Creta-
ceous age. But to whichever system they are ultimately referred,
it is at least certain, as stated above, that these beds lie near the
border line between the Cretaceous and Tertiary. They have the

™ Bull. U.S. Geol. Surv., No. 381 (1909), 39.

2 Proc. Wash. Acad. Sci., XI, No. 3 (1909), 219.

CRETACEOUS AND TERTIARY FORMATIONS 533

same stratigraphic position as the Laramie formation, with which
they correspond in whole or in part.

FORT UNION FORMATION

The Fort Union is one of the most important and best known
formations of the Northwest. It covers a vast area east of the
Rocky Mountains, stretching from Wyoming to the Arctic Ocean
in the valley of the Mackenzie River, and including several Cana-

Fic. 8.—Outcrop of Fort Union on Beaver Creek, northern Billings County,
showing ten coal beds. The thickest measures four feet, four inches.

dian provinces, much of western North Dakota, eastern Montana,
northwestern South Dakota, and central and eastern Wyoming.

The name Fort Union was first used by Dr. F. V. Hayden in
1861 to designate the group of strata, containing lignite beds,
in the country around Fort Union, at the mouth of the Yellowstone
River, and extending north into Canada and south to old Fort
Clark, on the Missouri River above Bismarck. It is a fresh-water
formation and is composed of clay shales alternating with soft,
rather fine-grained sandstone and containing many beds of lignite.

534 A. G. LEONARD

The Fort Union is remarkably uniform in color, composition, and
appearance throughout the region under discussion. The prevail-
ing color is either a light ash gray or yellow, but in places the beds
are nearly white. In Billings County, North Dakota, an upper
member of the formation appears in the tops of the higher ridges,
divides, and buttes, and resembles somewhat the Lance beds in
its dark gray color and its many brown ferruginous, sandstone
concretions. The lower member constitutes the typical yellow

Fic. 9.—Two coal beds on Little Missouri River in northern Billings County,
North Dakota. Upper bed is ten feet thick, the lower is near river level.

and light gray Fort Union and this is the only one present over
most of the region. Where both occur, the contrast between the
upper and lower members is so well marked and their contact so
clearly defined that it can be readily distinguished even at a dis-
tance and traced without difficulty, wherever it is exposed. Over
nearly one-half of Billings County a thick coal bed or layer of
clinker formed by the burning of the coal occurs just at the con-
tact. The strata forming both members of the Fort Union are seen .
along the Northern Pacific Railroad between Fryburg and Medora,

CRETACEOUS AND TERTIARY FORMATIONS 535

North Dakota. From the former station to the siding at Scoria,
‘the upper member is well shown in the badlands on either side,
while between Scoria and Medora the lower member appears.
Over a large area in southwestern North Dakota, the Fort
Union is formed fn part of white, sandy clays and very pure plastic
clays, which differ from any of the beds found elsewhere. They

Frc. ro.—A mass of burned clay or clinker formed by the burning of a thick coal
bed. Mouth of Deep Creek, Billings County, North Dakota.

occur in Stark and Dunn counties and adjoining portions of the
surrounding counties, where they are restricted to the tops of the
higher ridges and divides or to an elevation of from 2,450 to 2,600
feet above sea-level. Near their eastern border they lie about
600 feet above the base of the Fort Union and their maximum
thickness is 150 feet. These white, sandy clays are well seen
near Dickinson and Gladstone, and several miles north of Hebron.

The Fort Union formation everywhere contains numerous

536 A. G. LEONARD

beds of lignite (Fig. 8). These vary in thickness from an inch
and less to thirty-five feet, beds six, eight, and ten feet thick.
being common (Fig. 9). Coal is much more liable to be present
in the Fort Union than in the underlying Lance formation, for the
latter is practically barren of coal in many localities and over
large areas. One rarely finds an outcrop of the former where
several hundred feet of strata are exposed that does not contain

Frc. 11.—A burning coal bed. The surface over the coal has settled many feet
and the ground is broken by wide cracks from which gases escape. Typical Fort
Union beds in background.

at least one or more coal beds. These range from top to bottom
of the formation and do not appear to be confined to any particular
horizon or horizons. The aggregate thickness of the twenty-one
coal beds of southwestern North Dakota which are four feet and
over is 157 feet.

One of the most conspicuous features of the Fort Union is the
vast quantity of burned clay or clinker produced by the heat of
the burning coal beds (Fig. ro). This has been sufficient to burn

CRETACEOUS AND TERTIARY FORMATIONS 537

the overlying clays to a red or salmon-pink color and in many
places to completely fuse them to slag-like masses. The beds of
clinker vary in thickness from five or six to forty feet, or over,
and some of them can be traced many miles in the bluffs bordering
the valleys and in the ridges and divides, while large numbers of
the lower buttes are capped with these protecting layers (Fig. 11).

There are great numbers of excellent exposures of the Fort

Fic. 12.—The Tepee Butte bluff of Little Missouri River, 584 feet high, showing
dark colored upper member and light colored typical Fort Union below.

Union beds in the wide belt of badlands bordering the Little
Missouri valley from a few miles below Yule to the mouth of the
river, a distance of nearly 200 miles; numerous good outcrops are
also found in the exceedingly rough badlands which border the
Yellowstone on the east between Glendive and its mouth. While
outcrops are quite abundant throughout the region under dis-
cussion, nowhere are there such favorable conditions for the
study of the Fort Union formation as in the two areas just men-
tioned.

538 A: G. LEONARD

The following section is given both because it is typical of this
formation, and also since it includes the greatest thickness of beds
seen in any single outcrop. It is exposed in a high steep bluff
of the Little Missouri which is surmounted by the Tepee Buttes,
and is one and a half miles above the mouth of Deep Creek (Fig.

Feet Inches

12).
Sandstonesto top ole NepeeyButtest: arene ie eee 25
Shatersandy. yellows irc aaron ere) emer ie oe anes 17
Coal tics A Saas od Se rg ere eel aie gn ONG JO Ria at iL ee eI 4
Shale, darloorayesiae, scans ciate repatale nl ata nae hea jed tessa cyte WM re eM 21
Sandstone, brown, with many ferruginous concretions........... 23
Shralle yellow i) stccse ehh cia ea edioleace aca ta Ac uaa Meccan cee eae ese eat
Shale» carbonaceous sbrowal ms Mer Nnee ene ra tate aoe ce nanny
Coal re Aseria VR tee aay caluclate cast et can meen te en 6
Galleys parative iste. alae tee ca ee apa Ae eres cece area Ce mm 3
Sandstone aes ae wcente 2). con Weve ce irae ol a ibe aaee Nee car ene eerie II
Shalesidarks oraiy,. ole eae, 5 uCe) latte ice dees One acini aere ie eter eae ner 7
(G76): 1 eer es eect sac he SAR ane an MOR crane ole NS oe vn
A nF Leena Fh <attyt oecceanem erated tle een caine Oe ays ex asa amie Aces) feel 3
Sire Meanie arena rer ee eae MeN ee Cre Raine Avie men tats 8
Shalecar bona Geos salon O wane oye ee eee eee ee a I
Goalies ata Sesciarabaccheca mas seo) tee cami ce aan nee aN ee ane 2
Shalescarbonaceous, ro wine neice cence ene crane
(@/c-1] PRU a Ses ees rete eRe tre orl ees MSHS eat a Oe Malia Ae cree 3
Sandstomesjpassimommtorsiia le. ay eee seins ius reer te eae 23
Shale. yellow and tbrowm, sandy impacts.) s22ee oe ee 24
Sandstone tbroiwane <5 rd octet aes tee cine eee tee et 6
Coal soh0 ss Rae ae eeeny. NOIRE eater Oba Bees heh etka ee ae ant ze pena ee
Shaleyelloweandsbrowiie. see. wtt rs neuen ea atria eee esa 7
Sandstomes passimpaimtoushalle sais ey ps eee area eee ee) eee 18
Shalleand/sometcoall toc, yee eis cet iiee er ee eM tam eee ir
Samdstonese Soin. Rey tee aeonaie ieee ia: oe arog Rete hy Peart ie ape are ete 0)
Woogie ee iat SNe ae UEC ge a aie Uae ee a ca Re
Shale; carbonaceous, browsed far iene rele brett ay ce iene mnee
Cath Res Ne Lig Ut Neate aah NUE Mi ari ala eb aniague see a aey clean
Shale “browne No) Cb aise ea gree Seapets alias Warne MES ne eRe PRL TE
Goal igi eerie each city Jat ee nA oe grec dw ad ie eng ti
Shale;-brownandvpray.samdiyey 7: tee eee ee eae ee es 23
Bier ene Nae Mean cn eet ny ern aeesediin er mM rr are eek ete 3 o
Shale vcore) AOE et Se Ri anoint 8 Oe ae ana aL earn ae Pence
Gyo): 1 DARN errant LMC eea tami Ae ane Sie iter ios

Nw oO 0

Tie Cay it)

HN HH COD

CRETACEOUS AND TERTIARY FORMATIONS

539

Feet Inches

Shalesbrowilles 4. Pa arch aie Ket Can oa MCE cee ies. a ee SP a
Coal ieee cs k Sa Mis arya paicare icc retin A AE I
SIMA e ooh eae Belg CRED OAS ne a ar PT I
Qe S cio or.c 8 a. SUSIE cp eae ARR i em Oe
Sitalems ai ciple aieeweay sree pe ns owe ctv a he. cites Dee he 18
(CLOG GF aie dc: Gi as a le one a
Siialemmyelllowaeeeiametem ony errs ne ken ike i Se a) ees I
(COME oid AER 0 tN eee cen mang a a
SONS, SETONG HY 5 Sia ta acc ey are ERE ae 8
SINE. SURONGO ea 5 Sis ic ca eee eee etme Oe ER eR ee
(Goes. 6/5 a alesbe he cecokeed wlohe tee ates eee arr aoa I
Slalemcarbonaceous. LO WMyan ato sot cis ose Puno t ees be ek I
Sandstonemancillaceous yellows ya c.a. sce eels a eee a otis se ee ee 13
(COIL sie cp A eo aa aan a
Slalcrmsam Gly pay ell Wemtsrecsiane Sein or Su hsisdrecuers Blues auleaeieies eas 5
Stall ema lackemmeuae ra Hens, arise a Ab lone cae a ea eb
SE TNOISIGOHNG os is 5 Gace ies SERA CO NCURSES ce 6
Shrallemlolackw either Madey inl ya een ue) eS eared ok
Shalemsandyaviellowaand brow. 45.08. s 0. feces ae een 6
Sandstone, areillaceous, yellow tandigray: 0.0... 05 0).44. 0... 19
Saale, WOllOng crs eaou o gies a coer Sic ws Sacra oe ere eee ac 7
Samad stOmemve loan mmm er rencrtes tire NLR ase Mood Ea 5 4
Siralembnowmuam develo were ac. Mlhss cis eG os earn geen ce « ie)
SANG StOM ere CLAN Rem ee Mrs ened h nanan alle lech cue er 2 yy 2
Shall embrowiertare tee Me ate een. aoe elt ch, An wetness 2
Wo a rp ieee aa Na mht AMAL habe, Honan dilaeety ated g 2
Shale monownncarbOnaceOUsrts. ce ose Galan cia Glan bese tus nee aha’ I
Sita Comycllowepsaim Givi acer irn eer ROM teeta ico a, hl dere aM, I
SAAS OMG MeN mE Sen yp ete ey Serta e um oe cE ay eI Adh a whee tener ett 3
COI sso Sire aliaset a er AI Whe gee Gla Re on OA pate
Shalemsamaiyreviellowseewten ntettn arrester oes ee Sete ete AE ee 2
SAMGSTON CMV llOWecewn eh en MEME tte ike cat heen tua aia Ome 4
Coal pier ore ec re a dota Senge ts Gee Oe aise sae? I
Salem DRO Mere terrier cv nl oar Mia awn alias Ce Gail i
CO we See PG ae Reh ea eee na Rae ee RO Ac RIO CI
Stall eee etme ree Fares Cradle else csuik acne ne Sew HUW
CRO SSG eal ase eae roe a ee NED enter eeeoe mF 9
Shallesmonowitlnwe epee torr ef. S ut nce Wialh Wiaviacn ee aeba spans ey, BET
Shalewsain ciyaye ll Owece tts chee este ae oot esas Guat Meee Sayed in bh i
SAISON CAVE lll OW arererrear rise halos Ss ict eoaeshs. Aso Bt pl fieVoRab) Sea. Win, aie 26
COE Ye Se ety ies aaa OA Se eg
SMe Petp ean c hn ciel acree Lala cin wie ei Seances eet Ae

NNN DN

No bw» WwW

nB DAW FN

540 A. G. LEONARD

Feet Inches

Coal 2 aie cadai Bae ias rc ee hee cera te Eee ac eee 2 8
Shalle's Bo 5 Bek eit Sees SI ae ee ace en tr Wee Bde I
Cialis ey ia a he re Nee ay eee are ca me ea 8
Shale; browse yik Gaghl sen a demon eens fb cem eee ES eee 3
Sandstone, and sandy shale: yellow sileer. crn tees) hye apa eee 20
Shales brown. n2 yaerse see caves iene eaters a bees itoye meet eee erat eeeeam 6
Goal iS Seneca ctr he ote ee ee ae eee ere Ma eR er ee eee 10
Shale, Worowins: sec aes Ghia kia teh aceite opt erty aga cceette seas i 6
Goal er nee Sate Oe alee ae NN celeste cece tee I 6
Ghale ebro se Seu e090) J ree tea as ec tecke cv UN ns ete eae 2
CO a re ee ae ive NIRA A Anne Us en Mice SR ass AEN ae er eae 3 2
SIL (Dante es ae) aA Meg T Parts ene Shay Seti melee Rate I
(Gor oyc ea neem IRR ARO Mma aM MU ys CPE AEG) oy aire Mee nee I 8
Shales vellowamd-darkyorayys vets. cma scty ace truce Screen ee crete 20
Sandstome;syellows Mack ars Waits seu eoyerset ce hereue 2 Ncanmerner ecg erent 49 6
Coal ae AL Rae) OO eet SM ae Sate ih ea cen Me near ge ietraae 4
Sandstone and samdyashiale gare iysr gsr nei pel teh am ene oe I 3
Shales lathes i necyeth scarey ties agate ce aienee waar haat cuclt cag ents ere aneye 10
(O71 I een acer re Be ites Ae CNS eet chen aM Lie glow Gera SNN I 8
Sandstone, yellow, tomriver levelin. jos sme scree. weisers cane seme 12
| oys7.} sae aN a ete Rie roe eee Ar anerra ane IM rate Morena 6: c 584

The large number of coal beds occurring in the Fort Union is
well shown in the above section. The base of the section is prob-
ably not over 100 feet above the Lance beds, which disappear
beneath river level not many miles below. The outcrop thus
includes not only a large portion of the lower yellow and light
gray member of the Fort Union, but also about 183 feet of the
upper, dark-colored member. Where the uppermost beds of the
formation are found, as on top of such high buttes as Sentinel,
Flat Top, Bullion, and Black, they are seen to consist of a rather
hard sandstone 80 to too feet thick. This rock forms vertical
cliffs about the summits of these buttes, and huge blocks breaking
off from time to time accumulate at the base of the cliffs in great
talus heaps. On Sentinel Butte and the White Buttes, the White
River beds are seen resting directly on this uppermost sandstone
of the Fort Union.

The maximum thickness of the Fort Union is not far from 1,000
feet in western North Dakota, but over most of the region it has
undergone great erosion and from large areas hundreds of feet

CRETACEOUS AND TERTIARY FORMATIONS 541

have been removed. It was only by the erosion of this entire
formation that the Lance beds have been exposed along the Yellow-
stone and Missouri rivers and elsewhere, since the Fort Union
formerly covered the entire region.

The Fort Union beds, which are early Eocene in age, contain
a flora of nearly 400 species, and a fauna comprising both inverte-
brates and vertebrates. The plants contained in the following
lists were found in the yellow and light gray beds forming the lower
part of the formation. Most of them occurred either in concre-
tions or in layers of sandstone.*

NEAR MEDORA, NORTH DAKOTA

Sequoia Nordenskioldi Heer. Populus daphnogenoides Ward.
Populus cuneata Newb. Populus glandulifera Heer.
Ulmus planeroides Ward. Planera microphylla Newb.
Populus Richardsoni Heer. Carpites n. sp.

Populus amblyrhyncha Ward. Taxodium occidentale Newb.
Sapindus grandifoliolus Ward. Diospyros brachysepala Al. Br.
Viburnum antiquum (Newb.) Hol. Asplenium tenerum.

MOUTH OF DEEP CREEK, SOUTHERN BILLINGS COUNTY, NORTH DAKOTA

Viburnum Newberrianum Ward. Viburnum asperum Newb.

NORTHERN BILLINGS COUNTY, NORTH DAKOTA

Equisetum sp. Viburnum antiquum (Newb.) Hol.
Viburnum Newberrianum Ward. Viburnum Whymperi? Heer.
Diospyros—may be D. ficoidea Lesq. Corylus rostrata? Ait.

or new. Taxodium occidentale Newb.
Platanus nobilis Newb. Pterespermites Whitei? Ward.

WESTERN BURLEIGH COUNTY, NORTH DAKOTA, NEAR THE BASE OF THE FORT
UNION AT ELEVATION OF ABOUT 400 FEET ABOVE MISSOURI RIVER

Populus daphnogenoides Ward. Platanus Haydenii Newb. Young
Populus amblyrhyncha Ward. leaf.
Populus cuneata Newb. Viburnum sp.

Aralia notata Lesq.

CENTRAL BURLEIGH COUNTY, NORTH DAKOTA, NEAR BASE OF THE FORT UNION

Populus daphogenoides Ward. Platanus nobilis Newb.
Populus sp. ? Grewiopsis populifolia Ward.
Populus amblyrhyncha Ward. Euonymus ? sp.

t The plants were identified by Dr. F. H. Knowlton.

542 A. G. LEONARD

WESTERN DAWSON COUNTY, MONTANA

Onoclea sensibilis fossilis Newb. Populus genatrix Newb.
Populus cuneata Newb. Populus speciosa Ward.
Leguminosites arachioides Lesq. Cocculus Haydenianus Ward.
Celastrus pterospermoides Ward. Platanus Haydenii Newb.
Populus amblyrhyncha Ward. Plantanus nobilis Newb.
Populus daphnogenoides Ward. Sequoia Nordenskioldii ? Heer.
Populus arctica Heer (as identified Thuja interrupta Newb.

by Lesquereux). Glyptostrobus europaeus (Brongn.)
Populus smilacifolia Newb. Heer.

Populus nebrascensis Newb.

BASE OF THE FORT UNION IN SIGNAL BUTTE, FIVE MILES EAST OF MILES CITY,

MONTANA
Taxodium occidentale Newb. Corylus americana Walter.
Sequoia Nordenskioldii Heer ? Planera.
Glyptostrobus europaeus (Brongn.) Hicoria antiquorum (Newb.) Knowl-
Heer: ; ton.
Populus ? sp. ? cf. genatrix Newb. Hicoria ? sp. new.
Populus, possibly P. acerifolia Newb. Celastrus ovatus Ward.
Betula, sp. new? Sapindus grandifoliolus Ward.

Corylus rostrata Aiton.

The Fort Union beds contain many fresh-water shells, among
which the following species were collected:*

NORTHERN BILLINGS COUNTY, NORTH DAKOTA

Campeloma producta White. Viviparus trochiformis M. & H.
Viviparus retusus. Sphaerium formosum M. & H.
Viviparus leai M. & H. Bulinus longiusculus M. & H.
Campeloma multilineata M. & H. Micropyrgus minutulus M. & H.

Thaumastus limnaeiformis M. & H. Hydrobia.
Corbula mactriformis M. & H.
SOUTHERN BILLINGS COUNTY, NORTH DAKOTA
Unio priscus M. & H.

NORTHEASTERN CORNER OF MORTON COUNTY, 350 FEET ABOVE MISSOURI RIVER

Corbula mactriformis M. & H. Viviparus trochiformis M. & H.
Campeloma multilineata M. & H.

t Identified by Dr. T. W. Stanton. :

CRETACEOUS AND TERTIARY FORMATIONS 543

WESTERN BURLEIGH COUNTY, ABOUT 350 FEET ABOVE THE MISSOURI RIVER

Viviparus retusus M. & H. Unio sp. fragments.
Campeloma producta White. Corbula mactriformis M. & H.
Campeloma multilineata M. &. H. Viviparus multilineata M. &. H.

Vertebrate fossils are rare in the Fort Union formation. In
western North Dakota, near Medora, a few bones were collected
which were identified by Mr. J. W. Gidley as those of fishes, turtles,
and te aquatic reptile, Champsosaurus laramiensis. The latter
has been found by Mr. Barnum Brown in the Lance beds of the
Hell Creek region, and also in the ‘‘lignite beds” just, below the
typical Fort Union."

WHITE RIVER BEDS

The White River beds of the Oligocene occupy three small areas
in southwestern North Dakota, and several in the southeastern
corner of Custer County, Montana. The beds of this group are
found in White Butte, in southeastern Billings County, where
they cover an area from eight to ten square miles in extent, forming
the highest portion of the divide at the head waters of the North
Fork of the Cannon Ball River and Deep and Sand creeks. Ero-
sion has here left two ridges about two miles apart, with an eleva-
tion of 300 to 4oo feet above the surrounding plain. Three miles
to the west, on the opposite side of the valley of Sand Creek,
Black Butte rises 450 feet above the creek, being capped by the
same sandstone as that forming the top of the other high buttes
of the region. But the beds of the White River group are wanting
on Black Butte, although occurring at a considerably lower level
only three miles to the east. In White Butte they are, however,
seen resting directly on this upper sandstone of the Fort Union,
which outcrops at several points near the base of the western slope
of the western ridge and also at its northern end. This sandstone
here dips strongly to the east so that within a distance of three
miles its dip carries it from the top of Black Butte to the base
of the ridge on the opposite side of the valley, where it is over
200 feet lower.

™ Bull. Am. Mus. Nat. Hist., XXIII (1907), 835.

544 A. G. LEONARD

The following is a general section of the White River beds as
they occur in White Butte:

; ; : Feet Inches
11. Sandstone, rather fine-grained, light greenish gray in color,

weathering into a greenish sand; to top of White Butte...... 105

10; Clay, cray. to lehtsereenish=coloipmn. a i ers ane 20-25
g. Clay, hard and compact, calcareous, light gray, almost white;
forms hard ledges which make low vertical cliffs toward the top

of the butte, and weathers very irregularly -/-...-. 42.5... 34
8. Clay, dark gray, calcareous, the line of separation between this
clay and No. 7 is sharp and distinct, the clay being consider-

ably darker than the underlying sandstone. ne Leena, tae 46

. sandstore sight eray, rather coarse-graimediae 94. soe 20
6. Sandstone, very coarse-grained and pebbly; in places the peb-
bles are so abundant as to form a conglomerate. Shows cross-
lamination. Pebbles composed of quartz, silicified wood,
many varieties of igneous rock, among which porphyry is com-

“I

mon. Pebbles range in size up to 2 and 3 inchesindiameter... 26
5. Clayo very light gray, Slightly sandy, 490) see ae 5
4. Sandstone, light gray, very fine-grained and argillaceous...... 5 4
3. Clay, light gray to white, slightly darker than No. 2; contains
some fine Sand.s 5 422. Wyaaietan catsee cee Peers Pa eee ie) 6.
2: Clava very white and ipure usa os) acer ace rs ee te 6 6
1. Clay, white, containing some fine sand, hard and very tough |
when dry; rests directly on the sandstone of the Fort Union.. 14 4
(Ko 2) ice SME er ML ie Soe ee Or, Sey Rane Raat Crea Ae NEMA 298

In No. 8 of the above section was found the skull of an extinct
species of ruminant, Eporeodon major (?), which is found in the
Oreodon beds of the Oligocene.*

It will be seen from the section just given that the White River
group is here composed of white clays at the bottom, on which
rests a coarse sandstone which in places is filled with large pebbles;
this is overlain by about too feet of calcareous clays which in turn
are overlain by more than too feet of fine-grained, greenish sand-
stone (Fig. 13).

These deposits represent all three divisions of the White River
group, the lower or Titanotherium beds, the middle or Oreodon
beds, and the upper or Protoceras beds. In the foregoing section
Nos. 1 to 7 probably belong to the lower, Nos. 8 to ro to the middle,
and No. 11 to the upper division.

t Identified by Mr. J. W. Gidley.

CRETACEOUS AND TERTIARY FORMATIONS 545

It was probably this same White Butte area which was dis-
covered by Professor E. D. Cope in September, 1883. The dis-
covery was announced in a letter written from Sully Springs,
Dakota, and read before the American Philosophical Society.
The following is a portion of this letter:

I have the pleasure to announce to you that I have within the last week

discovered the locality of a new lake of the White River epoch, at a point
in this Territory nearly 200 miles northwest of the nearest boundary of the

Fic. 13.—The coarse sandstone of the lower member of the White River beds in
White Butte, Billings County, North Dakota, showing effects of rain erosion.

deposit of this age hitherto known. The beds, which are unmistakably of the
White River formation, consist of greenish sandstone and sand beds of a
combined thickness of about roo feet. These rest upon white calcareous
clay, rocks, and marls of a total thickness of too feet. These probably also
belong to the White River epoch, but contain no fossils. Below this deposit
is a third bed of drab clay, which swells and cracks on exposure to weather,
which rests on a thick bed of white and gray sand, more or less mixed with
gravel. This bed, with the overlying clay, probably belongs to the Laramie
period, as the beds lower in the series certainly do.

Then follows a list of 20 species of vertebrates which were
collected from this locality, including Trionyx, Galecynus gregarius,

546 A. G. LEONARD

Aceratherium, Elotherium ramosum, Oreodon, and Leptomeryx. The
white calcareous clay below the upper sandstone is now known to
carry fossils and the sand below this clay is probably to be included
with the White River group. Professor Cope, in common with
other geologists at that time, regarded the underlying beds as
belonging to the Laramie, but as already stated, they are now on
the evidence of their plant remains known to be Fort Union in age.

Mr. Earl Douglass spent some time in the White Butte locality
during the summer of 1905, and has described in considerable
detail the beds occurring here.’

In the middle member or Oreodon beds, he found the following
fossils: Ictops, Ischyromys, Palaeolagus, Merycoidodon culbertsoni,
Leptomeryx evanst, Mesohippus, Hyracodon, Gymnoptychus, Eumys,
and Aceratherium.

Mr. Douglass discovered another deposit of White River beds
about thirty miles north and east of White Butte, in Stark County.
The area, which is known as the ‘‘Little Bad Lands,”’ lies some
twelve to sixteen miles southwest of Dickinson. All three divisions
of the White River group are here present and a number of mamma-
lian bones were collected.

The third locality in North Dakota where the Oligocene occurs
is on top of Sentinel Butte, in northern Billings County, near the
town of the same name. The beds are here seen resting con-
formably on the massive sandstone which forms the top of the
Fort Union. The beds occur only on the northern end of Sentinel
Butte and their maximum thickness is not over forty feet. They
are clearly the remnants left by the erosion of a thicker and more
extended formation which doubtless once covered a large area
in this region. Where the strata are exposed in a low mound
near the northwestern edge of the butte they are seen to be com-
posed of light gray calcareous clay or marl, which contains, toward
the top, beds of a nearly white, compact limestone. This lime-
stone breaks readily into thin layers one-eighth to one-quarter
of an inch thick, and some of the thicker layers become siliceous
toward the center.

In one of the upper beds of this limestone are found the remains
of two species of fresh-water fishes. These fossil fishes were first

“Annals of the Carnegie Museum, V, Nos. 2 and 3 (1909), 281-88.

CRETACEOUS AND TERTIARY FORMATIONS 547

discovered on Sentinel Butte by Dr. C. A. White, who visited
the locality in 1882 and published an account of the deposit
containing them. ‘They were described by E. D. Cope as belong-
ing to a new genus and were named by him Plioplarchus W hitei
Cope and Plioplarchus sexs pinosus Cope.

Since the fishes were not closely related to any previously
described they did not serve to indicate the age of the beds in
which they were found, but upon stratigraphic grounds Dr. White
referred the strata to the Green River group of the Eocene, though
he was by no means confident that this was their true position.
In the light of more recent discoveries it seems much more probable
that these beds on Sentinel Butte belong to the White River
division of the Oligocene. It is now known that less than forty
miles to the southeast are other deposits which rest directly on
the upper sandstone of the Fort Union and which are known from
their fossils to belong to the White River group. On the other
hand, no beds of the Green River group are found any nearer
than southwestern Wyoming and it is not at all likely that they
ever extended this far north and east, while the White River
beds cover considerable areas in South Dakota and Montana.
The extensive erosion to which this region has been subjected
during many ages, and which is known to have removed at least
from 800 to 1,000 feet of strata over a large area, has left only a
few remnants of the White River deposits.

In southeastern Custer County, Montana, in the district
known as the Long Pine Hills between the Little Missouri River
and Big Box Elder Creek, the White River beds are known to occur.
They here have a thickness of at least 150 feet and are composed
of fine-grained, greenish gray calcareous clay, soft, compact,
white limestone, and calcareous clay. They resemble the White
River beds of the Slim Buttes in South Dakota.

The Oligocene beds of North Dakota and Montana are believed
to be in part lake deposits and in part river deposits. The lack
of uniformity, the cross-bedding, and the coarseness of the materials
in some portions of the formation are probably the result of deposi-
tion through river action. In other areas, as those of Sentinel
Butte and Long Pine Hills, the materials were perhaps laid down
in the more quiet water of a lake.

ON THE GENUS SYRINGOPLEURA SCHUCHERT®™

GEORGE H. GIRTY

The genus Syringopleura has recently been proposed? for a
brachiopod of the Spirifer group. It is typified by Syringothyris
randallit, a species which Simpson described as possessing the
internal structure of Syringothyris, along with a plicated fold and
sinus. As is well known, Syringothyris is a Spirifer having a high
area, a simple fold and sinus, and the characteristic “‘twilled cloth”
sculpture. Internally there is developed a delthyrial plate, not
to be confounded with the deltidial plates, which bears on the inner
side the split tube characteristic of the genus. Typical Syringo-
thyris is generally regarded as being an offshoot of the ostiolate
Spirifers. Professor Schuchert gives the following reasons for
establishing the genus:

Another phylum originated in the Atlantic realm of the Appalachian
province in Spirifer randalli, which also has a well-developed syrinx, but
differs from Syringothyris of the Mississippian sea in having a strongly plicated
fold and sinus. This stock must be separated generically from those of the
Mississippian sea because of its different phyletic derivation, and for it is
proposed the generic name Syringopleura (from syrinx and pleura or rib,
having reference to the plicated fold and sinus), with S. randalli Simpson
as the genotype.

Now I am compelled to question the validity of the genus
Syringopleura on all the points advanced by Professor Schuchert.

In the first place, it seems highly probable that S. randalli does
not possess the external peculiarity on which the genus was chiefly
founded—the plicated fold and sinus. Syringothyroid shells are
extremely abundant at the locality and horizon at which S. randalli
was found, and I have examined a large number of specimens
without in a single instance finding any which possessed the char-
acteristic mesial plications. It is possible, of course, that the

‘ Published by permission of the Director of the U.S. Geological Survey.

2Am. Jour. Sci.. XXX (1910), 224.

548

THE GENUS SYRINGOPLEURA SCHUCHERT 549

specimens coming before me all belonged to an abundant species,
while S. randalli represents a different and much rarer one. The
probabilities appear to me decidedly adverse to this hypothesis,
however, and the following statement of Professor Schuchert’s
is in point. He writes of Syringothyris: ‘At no time, however,
was there more than one species in a fauna, and all these are very
much alike.”

Thanks to the courtesy of the Academy of Natural Sciences of
Philadelphia, I have been able to examine the type specimens of
S. randalli, and this examination seems to bear out the opinion
expressed above. The specimens sent me as the types are three
in number (Nos. 9532, 9533, and 9534), only one of which, however,
was figured in connection with Simpson’s description.’ It is
an internal mold of a ventral valve. It is a fact that this speci-
men shows some very obscure, longitudinal markings at the bottom
of the sinus, but it is also a fact that Simpson’s drawing exagger-
ates these unpardonably.

When fossils are preserved as molds, the best opportunity to
observe external characters is naturally afforded by molds of the
outside. In the case of such species as S. randallz, internal molds
of the dorsal valve are more satisfactory than internal molds of
the ventral valve, because testaceous deposits on the inner surface
of the shell which tend to obscure such external features as the
plications were there less extensively developed. In internal molds
of either valve the marginal portions afford better evidence than
those near the umbo, because the secondary deposits were chiefly
formed over the older parts of the shell. On the internal ventral
mold which is the type specimen of S. randalli, the lateral costae
are well shown except in the cardinal and umbonal areas. In this
degree of expression they stop abruptly at the sinus. The anterior
part of the sinus, where the costae, if present, would naturally be
most conspicuously developed, is nearly, if not quite, smooth.
The posterior part is occupied by the large umbonal scars. It is
in the intermediate portion, where the test was probably still
appreciably thickened, though less so than at the umbo, which was
filled by the apical callosity, that the obscure radial markings can

tAm. Phil. Soc., Trans., XV, 441, Figs. 1, 2.

550 GEORGE H. GIRTY

best be seen. It is doubtful, however, whether these can be attrib-
uted to normal costation, which ought to be still better exhibited
toward the front, rather than to inequalities in the rapidly thinning
apical callosity, such as would be shown on the inside but not on
the outside of the shell. Similar markings have been observed
on other species of Syringothyris.

S. randalli occurs at the locality and horizon of the classic
_ association of Syringothyris with Spirifer disjyunctus.* S. dis-
junctus, or a species closely allied to it, occurs in equal abundance
with the Syringothyris. Superficially the two types are distin-
guished by the fact that one has a simple fold and sinus and the
other is plicated. Where this character is obscured, internal molds
of ventral valves might be confused on casual observation, although
one type possesses the syrinx and the other does not, and from the
evidence in hand it seems almost certain that Simpson did thus
confuse them, since one of the three type specimens of Syringothy-
vis randalli, all of which are internal molds of ventral valves, is
clearly a Spirifer. Although it does not show any surface char-
acters whatever, it has the internal characters of and almost cer-
tainly belongs to the form commonly referred to Spirifer disjunctus
in the Warren area. It appears plausible, therefore, that Simpson
confused these two forms, and seeing well-marked plications on the
fold and sinus of some specimens (S. disjunctus) felt justified in
putting them into his description and into his figure, although
they are only faintly suggested in the specimen from which the latter
was drawn. Conclusive evidence can come only through an
examination of the external mold of the type specimen, which is,
of course, impossible; or less adequately through the discovery
of other specimens unmistakably possessing the characters which
S. randalli is said to have. But, for my own part, I am fairly
satisfied that S. randalli is conspecific with the abundant asso-
ciated Syringothyris which clearly has a simple fold and sinus.

Granting, however, that S. randalli does possess the plicated fold
and sinus ascribed to it, let us examine into the argument by which
this character is thought to justify the erection of a new genus.

At Warren, Pa., at a horizon not far below the ‘“‘Sub-Olean conglomerate”’
in a series of strata which I at one time proposed to call the Bradfordian group.

THE GENUS SYRINGOPLEURA SCHUCHERT 551

Professor Schuchert says that the erection of a genus is demanded
by the fact that S. randalli has a different phyletic derivation from
typical Syringothyris.*. He is unfortunately not very explicit but
he apparently derives typical Syringothyris from the ostiolate
Spirifers and S. randalli (Syringopleura) from the aperturati.
But it is a fair hypothesis that S. randalli, the hypothetized ran-
dall1, may have come from typical Syringothyris by the introduc-
tion of mesial plications at so early a period that in the imperfect
condition of our record the two types seem to have developed nearly
simultaneously. Or, a second hypothesis is not negligible, that
the two may have sprung from some common ancestor, at present
unknown, which was intermediate between the ostiolate Spirifers
on the one hand (or whatever stock gave rise to Syringothyris)
and. Syringothyris and “‘Syringopleura”’ on the other. Professor
Schuchert offers no evidence to support his theory of the deriva-
tion of S. randalli as against these two other possible hypotheses.?

But even if we grant that there is a species with the characters
of S. randall1 and that it is derived from some other group of
Spirifers than that which gave rise to typical Syringothyris, a
scrutiny into the line of reasoning which justifies the erection of a
new genus from these premises will not, I believe, be without profit.
The argument seems to be that, because S. randalli and typical
Syringothyris belong to different phyla, therefore it is necessary
to place them in different genera.

Originally and strictly the word phylum in biology is used
for one of the larger divisions of the animal or vegetable kingdom,
but it seems to be often employed for small groups standing in a
line of genetic relationship. Thus phylum has a variety of mean-
ings as regards comprehensiveness. We might even say that two
Spirifers belonging to the same species but having different lines
of descent for numerous generations belong to different phyla;

t Professor Schuchert is perhaps a little misleading in his expression which seems
to limit Syringothyris to what he calls the Mississippian sea. Characteristic Syrin-

gothyris, of course, occurs not only associated with “S. randalli”” near Warren, but
at other localities and horizons in the same province.

2 Still other hypotheses are possible, equally plausible with these. For instance,
Hall and Clarke name a number of ostiolate Spirifers with incipient plications on the
fold and sinus.

552 GEORGE H. GIRTY

or we might say, as Professor Schuchert does, that two species
representing different sections of the genus Spirifer belong to
different phyla, and so on. Or, on the other hand, we might say
that two genera, such as Spirifer and Athyris, belong to different
pyhla, the one to the Spiriferoid stock, the other to the Athyroid.
The meaning of the word depends largely on the viewpoint of the
occasion, and any conclusion based on phyletic relationship is
almost nil unless the writer defines what he means by phylum.

But let us consider what the force of such an argument really
is in general terms. Put case that there are two Spirifers having
other characters identical but differing in the height of the area
or the length of the cardinal line or other similar characters and
belonging to different phyla in the narrowest sense. We do not
distinguish them as different genera or even different species, but
say that these differences concern minor characters in which expe-
rience has shown that individual specimens differ from one another
and vary at different stages of their growth. Put case again that
we have two Spirifers, one with simple fold and sinus and pustulose
sculpture, the other with plicated fold and sinus and finely reticu-
late sculpture, the two belonging to different phyla, in a broader
sense. Here, again, we do not say, as Professor Schuchert does,
that these species belong to different genera because they present
important differences and have different phyletic relations, for
the characters which they possess in common are such as we recog-
nize as characteristic of the genus Spirifer and the differences are
such as experience has shown to be useful only in specific dis-
crimination. Again, suppose we have two generally similar oval
brachiopods, one with internal spires, the other with an internal
loop, and belonging to different phyla, in a still broader sense.
We do not refer these types to different genera because they show
such and such differences and belong to different phyla, for the
differences are more important than those by which genera are
determined and we place the species in still more widely separated
groups. In other words, in such cases as these phyletic relation-
ship enters little, if at all, into the determination of taxonomy.
We go straight to the intrinsic characters of the form and accord-
ing to the nature and degree of its resemblances and _ differ-

THE GENUS SYRINGOPLEURA SCHUCHERT 553

ences determine the order of its taxonomic relationship to other
organisms.

On the other hand, let us suppose a rare case in which two forms
are Closely alike in most, or even all, of their mature characters but
at the same time they can be shown to belong to different phyla.
In this instance phyletic relationship has pre-eminent importance.
We cannot place the two types in taxonomic relationship more
close than the most remotely related of their ancestors. They
must be placed in different genera (at least) if that phyletic rela-
tionship is generic; in different families if it is familiar; in different
orders if it is ordinal, and so on. The logic of the situation seems,
then, really to be that the phyletic argument only sets a limit on
how close two types may stand in taxonomy, but does not enter
into the determination of how far apart they may stand. That is
based upon the physical characters of the mature individuals, not
upon development or on the theories of investigators.

Returning now to the case of Syringothyris and Syringopleura,
we find that the reputed ancestor of Syringothyris and the reputed
ancestor of the suppositious Syringopleura are different species
of the genus Spirifer. The phyletic argument,’ if used aright,
proves not that they must belong to different genera, but that they
cannot be placed in the same species. If we base a determination
of the relationship of Syringothyris and ‘“‘Syringopleura” on their
real, as distinguished from their speculative, characters, it would
appear that they should be regarded as specifically, but not generi-
cally, distinct. At least, the peculiarities which are thought to
distinguish Syringopleura are only rated as of specific import in
the true Spirifers, and I do not see why they should be more impor-
tant in the closely related syringophorous shells.

Therefore, it appears to me that Syringopleura is based on a

* The phyletic (phylic would be a much better term, but it unfortunately lacks
authority) argument, which really only serves as a check upon misleading or misunder-
stood direct evidence, to prevent two forms from being classed in too close zodlogical
categories, can rarely be used in paleontologic work because the phyletic relationship
is seldom, if ever, more than speculative. Even if the trend of the evidence were
correctly presented by him, the example set by Professor Schuchert in his proposed

genus Syringopleura is fraught with danger, since it would make our zodlogic classifi-
cation the prey of all sorts of theories, however ill-considered.

554 GEORGE H. GIRTY

false premise, on an unsupported assumption, and on loose reason-
ing, and that it cannot stand.

If, as remarked by Professor Schuchert, several different types of
Spirifer exhibit a tendency to develop the split tube, and if the
development of this structure may be looked for in almost any high
areaed member of the genus, far from adopting the course which
he advocates of establishing a new genus for every such manifes-
tation, I should feel that this series of facts materially lessened, if
it did not destroy, the value of the syrinx as a generic character.

The function of the syrinx is not definitely known. The most
probable explanation of its function, and the one adopted. by Pro-
fessor Schuchert, is that it is connected with the pedicle muscle.
Even in typical Syringothyris there is no cogent reason for inferring
that the soft parts possessed any structures different from those
of Spirifer. If so, this typical structure of Syringothyris is prob-
ably to be regarded only as a result of excessive shell secretion, and
it may well be questioned whether its employment as a generic
character is any more justifiable than it would be so to employ
the deposit of an apical callosity, with which the syrinx is perhaps
a concurrent manifestation, or of a thick test with attendant deep
muscular imprintation, a character regarded of little importance
in other types of brachiopods. The tendency to develop an
incipient syrinx in various groups of Spirifer contributes not a
little to justify such a low estimate of the taxonomic value of this
character.

PRELIMINARY NOTES ON SOME IGNEOUS ROCKS OF
JAPAN. I

S. KOZU
Imperial Geological Survey of Japan

I. SODA-TRACHYTE

Localities.—Matsu-shima and Kakara-jima, two islets, six and
a half kilometers northwest of the port of Yobuko, prov. Hizen,
Kytsht.

Occurrence.—As compact lava, associated with an alkaline feld-
spar-bearing basaltic rock.

Age.—Probably near the close of the Tertiary.

The following notes on the mineralogical and chemical char-
acters were made from the specimen collected from Matsu-shima.

Megasco pic characters.—The rock is blackish gray in color with
semiwaxy luster, and by weathering easily changes to light brown-
ish-gray with greenish tinge. The phenocrysts are of abundant
feldspar, and are not easily distinguishable at a glance on fresh
fracture surfaces, as their color is not white, but on weathered
surfaces exposed to the washing of sea waves the minerals, being
less attacked than the matrix, are as well marked as the coarse
grains of quartz in weathered sandstone. The mode of weathering
is a characteristic feature which enables us to distinguish the present
rock from other rocks of the environs. The feldspar phenocrysts
are thick tabular or sometimes stout prismatic, from 2 to 5 mm.
in length, in rare instances to mm., and very light bluish-gray in
color, for they contain abundant inclusions. The luster is not
purely vitreous but slightly waxy. The groundmass is aphanitic
and deep gray with light greenish tinge when freshly fractured, but
the color soon changes from dark brownish-gray to light gray by
weathering.

‘Published by permission of the Director of the Imperial Geological Survey of
Japan.

OL
On
Wn

556 S. KOZU

Microscopical characters.—The phenocrysts are of abundant
euhedral, or sometimes subhedral, feldspar. Almost all of them
are of anorthoclase, in which a small quantity of plagioclase is pres-
ent, either as nucleus of zoning which can be seen very rarely, as
perthite composing the faint perthitic structure, or as local patches
in the anorthoclase crystals. The groundmass is holocrystalline,
though small amounts of brown glass are locally present in the
vicinity of feldspar phenocrysts. It consists essentially of pris-
moids of alkaline feldspar, elongated toward the axis a. They
are arranged as in typical trachytic fabric. A smaller quantity
of thin and long prismoids of aegirine-augite, crystals or grains of
magnetite, and slender needles of apatite are disseminated through
the feldspathic groundmass.

Felds par, as phenocrysts, is soda-microcline, containing anorthite
molecules, that is, calctum-bearing anorthoclase. The shape gener-
ally shows euhedral form, principally bounded by crystallographic
faces (oo1), (oro), and (zor), and is thick tabular parallel to (oro),
or is very stout prismoid, or cuboidal. The characteristic habit
is derived from its appearing in a rectangular form on the face
(oro), owing to the domination of the planes (oo1), (201), and
(o10), as is the case with feldspar in ‘‘ Rectangelporphyre,”’ described
by Th. Kjerulf. The well-known rhombic form is entirely absent.
Parting parallel to (100) is so distinct that the cleavage pieces are
very difficult to get, the crystal easily breaking into pieces along
that face, as seen in Figs. 1 and 2. The twinning according to the
Carlsbad law is the most common, very rarely the Manebach type
is megascopically recognizable. Two other types (albite and peri-
cline) appear faintly between crossed nicols; sometimes they are
locally and irregularly distributed in the inner part of the pheno-
crysts. In some crystals microperthitic and microline structure
are visible. Zonal structure is not uncommon, but is not so distinct
as in the case of plagioclase. The outer zone usually shows a
slightly lower refraction than that of the inner part, but both are
lower than balsam. In one instance, plagioclase appears as a
nucleus in the alkaline feldspar. Aegirine-augite and greenish-
brown glass are comparatively abundant as inclusions; besides
these, apatite needles and magnetite grains are usually inclosed

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 557

in small amounts. The mean index of refraction of the mineral
measured by Wright’s ise m»>=1.526—1.531. The extinction
angle on (o10) is +5 to +9, and on (cor) o to +1: The
characteristic undulatory extinction is well marked. The plane
of the optic axes is approximately perpendicular to (oro), and the
negative acute bisectrix is nearly normal to (201). The apparent
optical angle measured on the section nearly parallel to (201),
by Mallard-Becke’s method, is 84° 44’ and 2V is 52° 20’, the mean
index of refraction being assumed as m»=1.528. The dispersion
is p>v.

Fic. 1 Fic. 2

The groundmass feldspars are also alkaline feldspar and occur
in elongated prisms, simple Carlsbad twinning being commonly
present. They are arranged as in trachytic fabric and the fluxion
is especially marked around the phenocrysts.

Aegirine-augite, as phenocrysts, is almost absent, and the largest
crystal, which was observed in 5 thin sections, measures 1.5 mm.
in length, but the average length of the prisms is o.2 mm. The
mineral is of bluish-green color, and is somewhat pleochroic from
bluish-green to the same color with yellowish tint. The greatest
extinction angle measured with respect to the ¢ axis, gave 45°. As
inclusions magnetic grains are common; and brown glass, appatite
needles, and feldspar laths can be detatched, the last being very
scarce.

558 S. KOZU

Olivine occurs in some specimens, as a very rare accessory in
an anhedral form.

Magnetite is very scarce as phenocrysts. Minute euhedral to
anhedral crystals are disseminated in the groundmass, and form
about 4 per cent of the whole. It is also associated with the
aegirine-augite.

Apatite is conspicuous as very minute needle-shaped crystals.

Chemical characters —Separate analyses were made of the rock
and of the porphyritic anorthoclase.

For the purpose of analysis of the mineral, the phenocrysts
were picked out of the weathered rock, in which the minerals remain
on the surface in a favorable state to be taken off from the matrix.
The feldspar material is quite fresh, but the surface and the inner
portions along the parting and cracks are stained by decomposed
products from the matrix and inclusions. To purify it as much as
possible, it was crushed into 1-2 mm. grains and was digested in
dilute hydrochloric acid at 80°C. for 24 hours, until it turned
white in appearance. But an intimate association with impurities
rendered it impossible to prepare a thoroughly clean sample, so
that the results of analysis are somewhat unsatisfactory. The
chemical analysis, made by S. Kawamura in the laboratory of
the Imperial Geological Survey of Japan, is as follows:

ok ON a a Ran Ee elie Aen dec net ate 64.98
Ya © eee eaten Seu rede, Geri ner Emenee: 7 19.62
Pes @ eres bortiheee, aia Re Sauer se reer anes ue cee eae 0.98
NT Oe ee es MORN, Aa 1 kare ae en dean ieee 0122
CAO rasp) clots Maaco ede ck kee eae oot Sane 3.48
INE ag os ina cation the aay Ce a ne 4.86
TOE Paps Reece cana gigs Mel cara ance te aera s, Ral eee 5.83

99.93

By the withdrawal of the excess of silica, lime, magnesia, and
iron as impurities mainly due to inclusions, the chemical composi-
tion of the mineral is shown approximately by the following ratios:

Si Qs eee cerca cep ce re tered Nea tage pres ee 63.08
Ta a Par rae ictal iy ease Dae rd ire Red PS ce 21.80
EY © LPS Ma RR rss tu, EME ei Na hn aR aN ee 8 3.24
[iE © FANE Reem entity hme a UE ain cece ARAL 5.39
UO Bien ecoregion 3 fea ye 6.49

NOTES ON SOME IGNEOUS ROCKS OF JAPAN

559

From these figures the formula of the anorthoclase is found to
be Or,.,3Ab;Any.
The analysis of the rock, by K. Takayanagi, and that of the
pantelleritic trachyte, by Fornstner, are given in the following

table:

* Loss on ignition.
A=Soda-trachyte, Matsu-shima, Kytsha.

B=Augite-andesite (pantelleritic trachyte of Rosenbusch), Porto Scauri, Pantelleria.

The norms, calculated from these analyses, are as follows:

Ratios from the norms

OuartzZaw....

Diopside. . .
Hypersthene
Magnetite. .
liimvenitereens
patiter usc.

€20/

oa .
OVS 09 OV ST Bet: (Or et

99-3

B
43

5 ie
ed:
30
54
45
BPAPS
-95

OV
HK

J (oy oy (OP Say sy

99.51

mn
i)
CF fp IS AS (6)

4.90

560 SKOZE!

In the quantitative system, the rock from Matsu-shima would
be classified under the name of laurvikose, near pulaskose. There
is a close resemblance in chemical characters between this rock and
the pantelleritic trachyte which was described by Fornstner as
augite-andesite, and is also laurvikose. The relationship between
them is shown in the above tables.

PRELIMINARY NOTES ON SOME IGNEOUS ROCKS
OF JAPAN. IP

S. KOZU

Imperial Geological Survey of Japan

Il. QUARTZ-BASALT

Locality.—Kasa-yama, near Hagi city, prov. Nagato.

Occurrence.—The rock occurs as a lava flow erupted at the vol-
cano Kasa-yama, which consists merely of an isolated cone of small
size, 112.5 meters above the sea-level and about 1,300 meters in
diameter across its base. In the summit, there is a perfectly
preserved crater, 25 meters in diameter and 13 meters in depth.
This small and regular cone stands in strong contrast to the topog-
raphy of the environs, where the geology is mainly composed of
granites and mesozoic sedimentaries, and especially to that of
table-lands or flat islands formed by basalt flows which poured
out here and there through the ground.

Age.—The eruption of the rock appears to be Diluvium and the
latest of the basalt in this region, which seem to have been erupted
at the period from the close of Tertiary to Diluvium.

Megascopic characters—The specimen collected from the lava
dam near the Shinto shrine at the eastern foot of Kasa-yama
is noteworthy for containing abundant quartz as porphyritic
grains in a hypocrystalline groundmass. It is black in color and
vesicular with small and irregular cavities, but has a high specific
gravity. The quartz, varying in size from 1 mm. to 5 mm., shows
an irregular outline, but sometimes almost hexagonal. Though
the percentage of quartz grains varies in different portions of the
lava, generally they are distributed uniformly and are clearly dis-
tinguishable from the groundmass by their color, as seen in the
photograph. Besides these there are only a few crystals of yellow

‘Published by permission of the Director of the Imperial Geological Survey of |
Japan.

501

562 S. KOZU

olivine as megascopic phenocrysts. This mineral is 2 mm. in
diameter, and is also fresh in aspect.

Microscopical characters —The mineral components are olivine,
augite, plagioclase, magnetite, and apatite, with phenocrystic
quartz. The microscopic phenocrysts are not abundant; among
them the olivine is most common, then follows the augite in nearly
equal amounts; the plagioclase occurs subordinately. The ground-

Frc. 1.—Quartz-basalt. 3. The white grains are quartz.

mass is hypocrystalline in texture and consists of lath-shaped
plagioclase, prismatic or granular augite, and magnetite crystals,
with abundant interstitial glass of light-brown color, clouded by
numerous globules.

Olivine belongs to the earlier crystallization among the mineral
ingredients of the rock, and is almost free from inclusions with the
exception of a few crystals of magnetite and glass, which are very
rare. It forms anhedral to subhedral shapes with finely ragged
outline, and about it minute granules of pyroxene may be observed.

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 563

The olivine is entirely fresh and remarkably but irregularly
cracked.

Augite is very faint yellowish or nearly colorless, and is more
abundant than olivine, though it is rarely present as microscopic
phenocrysts. As phenocrysts, it is anhedral, but in the groundmass
it is well shaped; elongated prisms are common. In rare instances,
twinning parallel to the orthopinacoid may be seen in the larger
crystals. In the reaction-border about the phenocrystic quartz,
augite is the only mineral constituent and is imbedded in brown
glass. Inclusions of mag-
netite, apatite, and glass
are sparingly present.

Plagioclase is basic lab-
radorite and appears in
well-formed, long _ pris-
moids with polysynthetic
twinning according to the
Carlsbad and albite law.
Zoning is almost absent.
Minute grains of pyroxene
and magnetite are present
as inclusions in small
quantity, with also a few
of glass.

Quartz occurs as a por-
phyritic constituent, and
the average diameter is about 2mm. The outline of the mineral in
thin section is usually irregular, but sometimes shows the bipy-
ramidal form referable to crystallographic faces, as seen in the
microphotograph (Fig. 2). Each grain of quartz is fringed with
a reaction-border, consisting of elongated prism and grains of
augite imbedded in brown glass. The minute prismoids are
arranged quite regularly. They are grouped radially, each group
_ containing a few crystals that converge toward the outer side of
the border, as seen in Fig. 2. In triangular, interstitial spaces
between each radial group granular augites are scattered irregu-
larly. In some instances, the deep invasion of the brown glass,

Fic. 2.—Bipyramidal quartz with reaction
border. X23.

564 S. KOZU

with very fine crystals of augite, is observed along the cracks in
the quartz. Glass inclusions with gas bubbles are present in
bipyramidal shapes, and ruptures starting from the four corners
of the rhombic sections are well marked in thin sections of the
mineral nearly parallel to the optic axis, as shown in Figs. 3 and 4.

FIG. 3 Fic. 4

Chemical characters —The analysis of the rock, shown in column
A in the following table, was made by T. Ono in the laboratory
of the Imperial Geological Survey of Japan. The analysis of the
quartz-basalt from the north base of Lassen peak, described by
Diller, is given in column B.

A B

SIO eA ay Cas ee, ene oa eee ee 56.08 SOn Sr
We G) ar encarta et eeaes n R ey nl ns ehe Tike} 16 18.10
He Ohad uterine. eee nen ae 2.46 4.26
KeOr - 6.97 2.68
Mg @ x Sie esa tees be eh cee Bare Avis?
OF Ieee ambit Nene meta Pais oyster ps th Ones
INA ON Sais ore ht tins lc ca ben Megereee: 2.02 Bn
KOs eae eka crise aerate kamen a 1.50 se 30
1c DO We eran PIN Nec aren er hese Onis 0.69
BETO er eus ede ci ate rele ae. aan Toit 0.48
PAO) ea, RR LW cee hk eal a EE tr O.14
IMI OM eee Seay nee ena 0.34 O.11
Ba QE ces 2a Sen ear Mine terete 0.04
Cr Ors eee ie er a ey ea arse tr
SHOE ee spe ene ieee Wa di aecie aa te 0.04
1 DSU G Teme Sg nie ale ree es ca hema ca tr

QQ. 22 100.10

A. Quartz-basalt (lava). Kasa-yama, prov. Nagato.
B. Quartz-basalt (lava). North base of Lassen Peak, California.

* Loss on ignition.

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 565

On comparing the analyses, it is obvious that the two rocks
are closely similar in chemical characters, but the rock of Kasa-
yama differs slightly in containing lower magnesia, lime, and alka-
lies, and higher iron and titanium; the low value of the first com-
ponent especially does not satisfy Harker’s hypothesis with regard
to the plotting of his diagram.

Norms, calculated from the analyses, are as follows:

A B

OE CUA SENG Scie Gs Ae ee 14.8 10.9
Orthoclasevee sentir foe fleck eee 8.9 he D
AM OTHE Seo LAN i ie cca eo ea ae 16.8 26.7
ANOLON SOUNDS Bnd Bre cin Se ae Ram 35°83 31.4
GCoruidl wine Gece 55 Se 0.2 an
IDO) ORTGIS 2G 5 aoe cate ee are ese ate 7.1
ela DETSEMECIMC Miia tee asain oc 16.9 8.6
IMACS os Geir fa ane Baul 6.3
TMS MTS eee setae s nee ne Dai 0.9

99.0 99.1

A B
al

ite” pHOCFooGd HO GMO GOdooU dG On 3.30 aS %S)
2 = Ss ca R EER CARMI Neat EAD ectct EE ER 0. 24 Only
K.0’+Na,0’

Cad’ areata ict a aCe ae 0.38 Ons
K,0’
NaO’ cc 0. 50 O25

By the Quantitative System these rocks are classified as
bandose.

PRELIMINARY NOTES ON SOME IGNEOUS ROCKS OF
JAPAN. IE

S. KOZU
Imperial Geological Survey of Japan

III. ALKALI-FELDSPAR-BEARING BASALTIC ROCK (FUKAE-GAN) AND
ALKALI-FELDSPAR-BEARING BASALT

Localities —Alkali-feldspar-bearing basaltic rocks were collected
from Fukae-shima in the Goto Islands; alkali-feldspar-bearing
basalts from Madara-shima, an islet northwest of the Yobuko
port, prov. Hizen; from O-shima, near the Island of Iki; from
Uramino-taki, near Omura city, prov. Hizen. These localities are
in the northern part of Kydshd or its outlying islands.

Occurrence.—The rock type, associated with olivine-basalt on
the one hand and with soda-trachyte? on the other, appears to
have an extended distribution over the northern part of Kytsht.
At Fukae-shima, this rock group forms the plateau and some
striking dome-shaped hills standing on it, as seen in the photo-
graphs (Figs. 1 and 2). There are well preserved or strongly
breached craters in the summit of each dome. The hills, in great
part, consist of ashes, lapilli, and slaggy lava, in which finely
shaped bombs may be found abundantly. The plateau is of hard
lava.

Age.—Near the close of Tertiary to Diluvium.

The specimens for the following descriptions were collected by
the writer from Fukae-shima; by Y. Otsuki from Madara-shima
and O-shima; and by D. Sat6 from Uramino-taki. They may be
classified in two groups by the mineralogical and chemical char-
acters.

I. Alkali-felds par-bearing basaltic rock (Fukae-gan in Japanese) .——

The rocks of this group collected from Fukae-shima are transi-

t Published by permission of the Director of the Imperial Geological Survey of
Japan.

2 Jour. Geol., XTX (1011).

566

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 567

tional forms in both texture and mineralogical characters, owing
to their crystallinity, but are closely alike in chemical properties.
They are represented by three types as described below.

As the first type, a bomb ejected from the volcano Ondake: was
selected for the following description and chemical analysis:

View from the northwest

Fic. 1

Megascopic characters.—This rock type is aphanitic and black
in color. Scattered magnophyric feldspars are the only con-
stituents visible to the naked eye. The groundmass is vesicular,
and the vesicles are small and round. The phenocrysts are of
fresh aspect and show rather euhedral forms, short prismatic or
tabular, and in some instances are of considerable size, reaching
20 mm. in length (Fig. 3). Olivine, which is present as abun-
dant microscopical phenocrysts, is scarcely recognizable even by
the aid of a lens.

568 SOLU

Microscopical characters —The microscopic phenocrysts in this
type of rock are of olivine in great part, with subordinate andesine.
The groundmass is hypocrystalline and is filled with small and
round vesicles (Fig. 4), looking like the outline of leucite.

Feldspar.—This mineral shows distinctly two different habits.
The phenocrysts are stout prismoid, sometimes tabular, and some-

ha: Oshima
ALS Z Koitabeshima Oilabeshema ——_———___.
SSS = —————.
Midake Usudahe

pa ee ee

View from the north west

Fic. 2

what rounded. They are andesine (Ab,An,), with a mean index
of refraction slightly higher than ny=1.554. They contain abun-
dant small particles forming an outer zone, and round it usually,
thin and clean layers with different composition, but the difference
between each layer is not pronounced. Twinning is scarce, and in
rare instances undulatory extinction can be observed. Feldspars
forming the groundmass are slightly more sodic than the pheno-
crysts, and occur in elongated or rather slender shapes. They are

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 569

marked by irregular cracks, filled with isotropic, low refractive,
and colorless, substance. Twinning according to the albite law
is common.

Olivine occurs in two-sized crystals. The larger ones are abun-
dant and play an important réle as microscopic phenocrysts. Their
shapes are equant or prismoid. In many instances, the outlines
of crystals are irregular by invasion of groundmass, sometimes

Fic. 3.—Andesine phenocryst, natural size

extremely narrow and deep, parallel to crystallographic faces,
showing the successive growth of the mineral, but the general out-
lines are referable to crystal forms (Figs. 5 and 6). Though
distinctly cracked they are entirely fresh and inclose clouded
glass, but are free from other inclusions.

Augite forms magnophyric crystals which are very rarely seen
in hand specimens. The minute grains in the base, showing high
refraction, appear to be augite.

570 S. KOZU

Magnetite clouds the base as minute grains or dusty particles,
and their abundant presence affects the color of the rock. Apatite

Fic. 4.—Microphotograph of the first type
of the first group, magnified 30 times. The
minerals seen in the figure are olivine micro-
phenocrysts and andesine prisms.

appears mostly as inclusions
in feldspar.

The second type collected
from Ohama in Fukae-shima
is more crystalline. Alkali-
feldspar appears locally in
the crystalline part as the
border of the plagioclase of
the groundmass. The augite
crystals are comparatively few
and occur in small anhedral
forms. The magnetite crys-
tals are more numerous in
this type of rock than in the
first one, are somewhat larger,
but are also anhedral in shape

(Hig. 7):

The third type collected from Masuda in Fukae-shima is holo-
crystalline, and in some parts has typical ophitic texture. The

IESTGsn5

Fic. 6

Fics. 5 AND 6.—Showing irregularly outlined olivines. X55

mineral components are andesine, alkali-feldspar, augite, olivine,
magnetite, and apatite. The andesine is distinctly cracked, with

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 571

invasion of colorless, low refractive and isotropic substance as in
the above types. The alkali-feldspar occurs as the border of almost
all crystals of andesine in the groundmass. The augite is light
purple in color, and is xenomorphic toward plagioclase. The mag-
netite frequently occurs in crystal form.

Il. Alkali-feldspar-bearing basalt.—

This group differs from the above in the presence of labradorite
in the place of andesine, as the essential component.

The specimen from Madara-shima is dark reddish gray in color
with semiwaxy luster. It is holocrystalline, fine granular, and

Fic. 7.—Microphotograph of the Fic. 8.—Microphotograph of the
second type of the first group. X3o. third type of the first group. X3o.

inconspicuously porphyritic, with not abundant magniphyric
feldspar and less pyroxene.

Under the microscope the rock consists of labradorite, alkali-
feldspar, augite, olivine, titaniferous iron ores, and apatite. The
labradorite is subhedral to euhedral, twinned according to the
Carlsbad and albite laws, and commonly prismatic in shape.
Zonal structure is rarely seen. Each of the feldspar crystals com-
posing the groundmass is enveloped by a shell of alkali-feldspar.
The augite is light greenish yellow with purple tinge, and is sub-
hedral to anhedral, stout prismatic to equant. The larger ones are
indistinct phenocrysts; the minute grains are interstitially dis-
tributed in the groundmass with magnetite crystals. The olivine

572 SUKOZE

as microscopic phenocrysts is subhedral to anhedral, and altera-
tion into iddingsite is commonly visible along cracks and in marginal
portions. The texture of the groundmass is somewhat inter-
sertal, and is characterized by divergent arrangement of prisms
of plagioclase enveloped by alkali-feldspar, with interstitial gran-
ules of augite, olivine, and magnetite (Fig. 9).

A more distinctly crystalline and coarser type is a specimen
from O-shima, an islet, near the Island of Iki.

Megascopically the rock, more or less decomposed, is evidently
holocrystalline, but the indi-
vidual crystals are scarcely
recognizable, though the di-
verse arrangement of prismoid
feldspars, 1.5 to 2 mm. long,
is well marked in the hand
specimen. The color is light
gray, On account of the
abundant feldspars, and is
dotted by dull reddish brown
spots produced by decompo-
sition of the olivine. Rare,

Fic. poe Micronnotormaph of the alkali- inconspicuous phenocrysts are
feldspar-bearing basalt from Madara-shima. tabular, white feldspar; irreg-
A38; ularly shaped black augite;
and equant, dark reddish olivine. All of them are less than 3 mm.
in diameter.

Under the microscope (Fig. to), the texture is transitional from
doleritic to intersertal, as the augite is xenomorphic toward feld-
spar in one case and automorphic in the other. The mineralogical
constituents are as before, but the presence of broad bands of alkali-
feldspar enveloping labradorite is especially noticeable (Fig. 11).
In some crystals, the alkali-feldspar has more than three times the
volume of the labradorite, that is,o.75 mm. in length and 0.09 mm.
in width (Fig. 11). In general, the labradorite is in extremely
elongated prisms, twinned according to the Carlsbad and albite
laws. The augite is anhedral to subhedral, prismatic to equant.
In color it is light purple. The magnetite frequently occurs in

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 5S

anhedrons 0.35 mm. in diameter. The apatite is noticeable in
elongated prisms.

The most finely grained variety is from Uramino-taki. It is
light gray, compact with a few vesicles, and nonporphyritic, some-
times with nodular olivine. There are groups of scaly, blackish
brown mica in the vesicles.

Under the microscope it is almost holocrystalline and granular.
The mineralogical components are the same as in the previous
variety, with a small quantity of biotite, which usually occurs in
cavities. The biotite is reddish brown and strongly pleochroic.
Its apparent optical angle (2£) varies between 37.5° and 29.5°.

Fic. to Fic. 11

Chemical characters —Of the first group of rocks a complete
analysis was made of the first type (Bomb) and two partial analyses
of the second (B) and third (C) types, by K. Yokoyama. Of the
rocks of the second group a complete analysis of a specimen (D)
collected from Marada-shima was made by T. Ono.

The three analyses A, B, and C of the first group show a close
relationship in chemical characters, notwithstanding they have
different mineralogical components due to their crystallinity. For-
eign rocks that have a close resemblance in chemical characters
with the rocks of this group are olivine basalt (E) and orthoclase-
bearing doleritic basalt (F) of New South Wales, described by

574 S. KOZU

G. W. Card. For the sake of comparison, these analyses are given
in the following table with those of the rocks under consideration.

A B c D E FE G

SiO sn eee | 48 . 33 49.15 48.70 | 52.109 48.98 53-21 49.24
ALOT see | 16.29 eer ore 19.74 16.88 17.84 15.84
HO ec Bed: 4.72 3.30 3.80 6.09
FeOne ea eee 8.73 6.28 7.29 522 7.18
Me Qin ances ease. ©. 2.24 5. 27 2.96 2.02
CaO si es ek. gare: er S250 6.99 8.86 6.48 5.26
INE WON: Garant 5 Peo 50) 3.64 885 3.48 3.30 3.36 Gai
COE See tale eet er I.49 1.61 TA 2.04 2.11 3.03 Pe io)
HO ares. et Raateaped / 0.52 0.65 1.08
HOS fy oeee S| a8 | noe | aes
LO ae ine) real n.d. n.d. 0.06 0.02 n.d.
LO Hu a iouia ea nane | 2.40 n.d. 1.28 I.O1 1.84
| AO VAG Wee ti se le MOR7O) n.d. ©.30 0.44 TeAU7,
Ro) el guar te Mian. (iemesayelt | n.d. none 0.09 n.d.
Clana a creer fee angele Ve n.d. 0.02 o.1I n.d.
Vin Oe eae Ori n.d. 0.31 0.32 0.29
ClO aaa Ming 0.06 0.06 Ba On2r

Potalge warn 99.99 99.99 | 100.41 99.88 | 100.46
SPiGas oie: 2.562 | on 2.869 2.768 2.79

Bomb ejected from the volcano Ondake, Fukae, the Gotd Islands, Ana-
lyst, K. Yokoyama.

Lava erupted from the volcano Ondake, Ohama, Fukae, the Goto Islands,
Analyst, K. Yokoyama.

Lava erupted from the volcano Ondake, Masuda, Fukae, the Goté Islands,
Analyst, K. Yokoyama.

D. Lava, Madara-shima, prov. Hizen, Analyst, T. Ono.

E. Olivine-basalt, one and a half miles north of St. George’s head, N.S.W.
F. Orthoclase-bearing doleritic basalt, south side of Croobyar Creek, N.S.W.
G. Mugearite, Druim na Criche, 5 miles S.S.W. of Portree, Skye.

The norms calculated from these analyses are as follows:

A D E F G

GIO Hae Anew vee st WA mle Wiig aa ep oe ee 3.2 eat 4.9 see
Orthoclase Wer Seatac ohlnap alsa ah aleher is suceaes 8.9 11.7 12.2 17.8 12.2
Albite._ KATO R OE re are melo eee 30.4 20.3 28.8 20.7 44.0
RUNTIME Grado cnguavecdvabose ds 23.9 32.3 24.7 24.5 13.6
Sodium Chlorid Gees sis mca mone SS ane aan 0.4 pep
Diopside science eerie mo 2 14.6 3.0 3.4
Hypersthene Ran te einen a Tented Wk 2.7 12 Ras 10.8 Teal
Olivine. SPOON AE Rc nace ears ee II.5 9.7 te 7.6
Magne titer tetra tr eer heals 6.7 4.9 5.6 8.8
Imenite EMS ey arr ote et a rip ee aie hints 4.6 2.4 2.0 Bx
IADALIEO Saree ceca ee ae ieee 1.9 0.7 1.3 Boi
99.5 97-5 98.0 97-9 97-3

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 575

Ratios calculated from the norms are as follows:

By the quantitative system, A, D, E, and F would be classified
under the name andose and G under akerose.

From the tables given above, it is clear that the rocks from
Fukae differ from normal basalt, in containing a high percentage
of alkalies in proportion to the silica contents, especially of soda,
forming normative andesine Ab,;sAn,,, which is slightly more calcic
than the modal plagioclase. Though the alkali-feldspar is not
present as a recognizable mineral in the first type (Bomb) of the
first rock group, its molecule is to be looked for in the glass-base.
In the second and third type, the alakli-feldspar is seen in the modal
state. The chemical resemblance between the rock of Fukae, A,
and the olivine-basalt from St. George’s Head, E, is very close. The
differences between them are lower potash for orthoclase, slightly
higher soda for plagioclase and higher normative ilmenite in the
Fukae rocks, compared with the olivine-basalt, of St. George’s
Head. Generally the rock is characterized by properties mineral-
ogically and chemically intermediate between the mugearite, G,
described by Harker, and the olivine-basalt described by Card,
though it is very near to the last rock, and it differs from shosho-
nite described by Iddings in being dosodic.

The rock from Madara-shima, D, differs slightly from the Fukae
rock in the lower value of magnesia and in higher percentages of
silica and potash, and of alumina which increases the normative
anorthite. It has a close resemblance in chemical characters to
the orthoclase-bearing doleritic basalt, F, from Croobyar Creek,
New South Wales, described by Card. .

REVIEWS

Gypsum Deposits of New York. By D. H. NEWLAND AND HENRY
LEIGHTON. New York State Museum Bulletin 143, Albany,
TOUOs = Da OAe

The bulletin presents a concise but complete description of the
gypsum deposits and the gypsum industry of the state of New York.
The workable deposits are restricted to the Salina state of the upper
Silurian and are pretty generally confined to a single formation of this
series, the Camillus shale. The geology of the Salina series is carefully
and clearly set forth.

Considerable attention is given to general questions relating to the
origin of gypsum, its properties, and the theory of its transformation
into plasters. The reviewer is pleased to note that the section devoted
to the description of mines and quarries is much shorter than is usually

found in a report of this character.
1d IR Jog

Report on a Part of the Northwest Territories Drained by the Winisk
and Attawapiskat Rivers. By Witi1amM McINnnEs. Geol.
Survey of Canada, No. 1008. Pp. 54; Figs. 5; Map 1.

In this report the author gives the results of a reconnaissance survey
of the country to the southwest of Hudson Bay. Adjacent to the bay
there are gently folded Silurian limestones and dolomites, probably
of Niagaran age. Outside this belt comes a belt of bowlder clay 160
miles in width, overlain by post-glacial marine clays, which, below the
Boskineig fall in the Winisk River, have an altitude of 350 feet above
sea-level. Beyond this again is the Laurentian peneplain, of Archean
granites and schists. This is the customary rocky-lake country, heavily
drift covered in places. Glacial striae on exposed rock surfaces indicate
a glacial movement toward the S.S.W.

The writer also gives a general description of the canoe routes, flora
and fauna of the country, climate and possibilities of agriculture.

HeCuc

576

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VOLUME XIX NUMBER 7

THE

JOURNAL or GEOLOGY

A SEMI-QUARTERLY

EDITED By

THOMAS C. CHAMBERLIN AND ROLLIN D. SALISBURY
With the Active Collaboration of

SAMUEL W. WILLISTON ALBERT JOHANNSEN WILLIAM H. EMMONS
Vertebrate Paleontology Petrology Economic Geology

STUART WELLER WALLACE W. ATWOOD ROLLIN T. CHAMBERLIN
Invertebrate Paleontology Physiography Dynamic Geology

ASSOCIATE EDITORS

SIR ARCHIBALD GEIKIE, Great Britain’ GROVE K. GILBERT, National Survey, Washington, D.C.

HANS REUSCH, Norway RICHARD A. F. PENROSE, Jr., Philadelphia, Pa.
GERARD DEGEER, Sweden WILLIAM B. CLARK, Johns Hopkins University
ORVILLE A. DERBY, Brazil WILLIAM H. HOBBS, University of Michigan

T. W. EDGEWORTH DAVID, Australia FRANK D. ADAMS, McGill University

BAILEY WILLIS, Argentine Republic CHARLES K, LEITH, University of Wisconsin

OCTOBER-NOVEMBER, 1911

CONTENTS

HEI TOUMNN ORE T 40 Sons 8 ee ie Oe Gaieoer (CALVIN
PEE WENORO OW ASOSTASY «202, 2 \ 2 2e4 6s, 72 = ee SAR MON| Lewis
SPECULATIONS REGARDING THE GENESIS OF THE DIAMOND Orvittr A. DERBY
PRELIMINARY NOTES ON SOME IGNEOUS ROCKS OF JAPAN. IV - - -S. Kézu
FACTORS INFLUENCING THE ROUNDING OF SAND GRAINS - - Victor ZrectER
THE UNCONFORMITY BETWEEN THE BEDFORD AND BEREA FORMATIONS OF |

NORTHERN: OHEO <5 200-0 sea eZ - - - - WILBUR GREELEY BURROUGHS
TTC IRTUNG sy a EUR ane ge Nee eames mt sia WO on

SIMCDINES TRUTSILICC 00 (On Rea 2 elas ee na EY CS Ae

The Untversity of Chicago press
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577
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The Fournal of Geology

Published on or about the following dates: February 1, March 15, May 1, June 15,
August 1, September 15, November 1, December 15. :

Vol. XIX CONTENTS FOR OCTOBER-NOVEMBER, 1911 No. 7

THE IOWAN DRIFT 2) 32) St ie ee Oe eee ee Oo SAMUEED CALVING ta77
THE THEORY OF ISOSTASY - - - - - .- 9- = = = “=. =. = =. Harmon Lewis 603
SPECULATIONS REGARDING THE GENESIS OF THE DIAMOND - - = = Orvitte A. DerBy 627
PRELIMINARY NOTES ON SOME IGNEOUS ROCKS OF JAPAN. IV - - - - -S. Kézu 632
FACTORS INFLUENCING THE ROUNDING OF SAND GRAINS - - - - - - Victor ZIEGLER 645
THE UNCONFORMITY BETWEEN THE BEDFORD AND BEREA FORMATIONS OF NORTHERN
OHIO- -- - - ~- ee =) WILBUR GREELEY BURROUGHS 655
EDITORUAL§ (oe eo Se age AE Re GORE ea mcd SPN eke ar Ato ee be ee eee ee (Coe eG)
REVIEWS? 2 200 Si oss ieeeeaion navi cola. aeea tng taal ew inh ep Naat <2 een eee We) ea OIE

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Ce ine

ae Es

ROUWRNAL OF GEOLOGY

OCGROBER-=NOVEMVMBER, ror

THE IOWAN DRIFT
SAMUEL CALVIN

CONTENTS
INTRODUCTION

Is there an Iowan Drift ?
Has the Term Iowan Been Correctly Applied ?
CAUSE OF CONFUSION IN USE OF THE TERMS KANSAN AND IOWAN
EFFECT ON TEXTS AND Maps oF MAKING CERTAIN PROPOSED CHANGES IN
USE OF THE TERMS
EVIDENCE CONCERNING THE IOWAN DRIFT AND ITs GEOLOGICAL RELATIONS
1. The Iowan Drift IS
2. The Iowan Drift is Young as Compared with the Kansan
3. The Iowan Drift is not a Phase of the Kansan
4. The Iowan Drift has very Intimate Relations to Certain Bodies of
Loess
5. The Iowan Drift is not Related to the [linoian

INTRODUCTION

Is there an Iowan drift? Whatever the reader may think
about it, the question seems to be in order. Three papers have
recently appeared in which the Iowan drift receives more or less
attention." Two of the papers go so far as to question the very
existence of such a sheet of drift as that which geologists have for

Frank Leverett, ‘‘Weathering and Erosion as Time Measures,” American
Journal of Science, XX VII, May, 1909.

, “Comparison of North American and European Glacial Deposits,”’
Zeitschrift fiir Gletscherkunde, IV, Berlin, 1910.

T. C. Chamberlin, ‘‘‘Comparison of North American and European Glacial
Deposits,’ by Frank Leverett;”? a review of the second paper, Journal of Geology,
XVIII, No. 5, July-August, roto.

Vol. XIX, No. 7 SET

578 SAMUEL CALVIN

some time been calling Iowan. The third paper raises the question
whether, even if there is such a drift, the name it has been wearing
should not be applied to something else. It is possible that the
questions raised by these papers may never be settled to the satis-
faction of everyone, because men do not always see alike; but a
few facts bearing on the subject may be worthy of consideration.

CAUSE OF CONFUSION IN USE OF THE TERMS KANSAN AND IOWAN

The doubt as to the correct use of the terms Kansan and Iowan
is the one that deserves first and most serious attention. This
doubt has arisen naturally and for admittedly good reasons, but
it is all due to the fact that in the earlier discussions of the Pleisto-
cene deposits of northeastern Iowa it was assumed that there were
but two drift sheets east of the Wisconsin lobe which occupies the
north-central part of the state. The two supposed drifts were
named by McGee? the Upper and the Lower till. The view that
there are but two tills in this area was adopted by Chamberlin
in his classic contribution to the third edition of The Great Ice Age,
by James Geikie,? and the name East-Iowan was given to what
was assumed to be McGee’s Upper till, while what was taken to
be the Lower till was called Kansan. There are, however, three
drift sheets in the region, and the attempts to describe three
formations in terms of two led to confusion. In some cases the
upper and middle sheets were described as a unit; in others the
lower and middle were treated as one; much more frequently the
lowest was ignored, and the descriptions of the “lower” and
“upper” tills were drawn from the other two. The presence in
certain localities of a forest bed or interglacial gravels, which it
was assumed always lay between what the authors described as
upper and lower tills, as East-lowan and Kansan, complicated
matters still further. There are, indeed, many positive references
in the original texts to this forest and gravel horizon—since called
Aftonian—as the plane of separation between the two drift sheets

: Paper on “The Pleistocene History of Northeastern Iowa,’ by W J McGee,

Eleventh Annual Report of the United States Geological Survey, Part I, 1891, pp. 189-577;
and other papers by the same author.

2 The Great Ice Age, 3d ed., chaps. xli and xlii, ‘Glacial Phenomena of North
America,” by Professor T. C. Chamberlin, pp. 724-74, 1895.

THE IOWAN DRIFT 579

at that time credited to the region; but if the texts relating to the .
subject are carefully read and the maps published in connection with
them are examined, it will be seen that the view that the lower till,
the Kansan, lies below the Aftonian is untenable. For example,
the description of the materials and prevailing color of the upper
till on p. 476 of the Eleventh Annual Report is true for only the
third of the drift sheets and is at variance with the facts if intended
to include the middle till. The sdme is true of the reference to the
large granite bowlders as ‘“‘the most conspicuous element of the
upper till,’ on p. 481. On the other hand, the characteristics
assigned to the lower till in the comparisons made between it and
the upper on p. 479, are all features that belong to the middle
drift sheet; in no true sense are they descriptive of the sub-Aftonian.
It is true that at the end of the paragraph there is a reference to
the ‘‘forest bed” as a plane of separation between the upper and
lower tills, but the characters which the author saw and so cor-
rectly and graphically described belong to a super-Aftonian till and
to nothing else.

If now we turn to the chapters on “‘ Glacial Phenomena of North
America,” contributed by Professor Chamberlin to Geikie’s Great
Ice Age, we shall see again how the preconception that there were
but two drifts where three actually exist, led unavoidably to con-
fusion. It is no reflection on anyone that such confusion crept in
in the earlier discussions. Some things are unavoidably overlooked °
by the pioneer who opens up for us new fields of science, and we
can but admire the genius and the insight of the masters who
taught us how to read the complicated history of the Pleistocene
deposits of the Mississippi Valley. As in the Eleventh Annual
Report, so in the Great Ice Age, it is two super-Aftonian tills that
are most frequently referred to in the text, and most accurately
represented on the map opposite p. 727 as, East-Iowan and Kansan.
The distinguishing characteristics of the upper and middle drift
sheets could not be more clearly or more succinctly stated than is
done on p. 760 of the work cited where, speaking of the East-lowan,
it is said:

In Iowa the granitic types predominate. Immense bowlders are freely
scattered over a portion of the surface. As greenstones prevail in the lower

580 SAMUEL CALVIN

till, there is a petrological as well as a stratigraphical basis for separating the
two formations. ....

The most notable feature of this drift sheet is its connection with the main
deposits of loess. .... The East-Iowan till sheet is, however, associated
with loess of such exceptional extent and nature as to make this epoch especially
notable on account of this relationship. As already stated, the till graduates
at its edge into loess that spreads away from its border.

The statements quoted can be interpreted in but one way.
They are true in case the term East-Iowan was applied to the
uppermost of the three till sheets in Iowa east of the Wisconsin
moraine. ‘There is just one till in which “granitic types predomi-
nate.”’ There is just one of which it can be said that ‘immense
bowlders are freely scattered over a portion of the surface.’”’ There
is just one that bears the described relation to the loess. While
greenstones occur in all three of the till sheets of the area under
consideration, it is in the middle sheet that they are most con-
spicuously prevalent.

The statement on p. 756 of The Great Ice Age, clearly implied if
indirectly made, that “the Kansan formation emerges from beneath
the overlapping East-Iowan formation to the extent of 200 miles
at the west”’ can apply only to a sub-Iowan, but super-Aftonian
drift. It cannot possibly apply to the sub-Aftonian for the reason
that at the time it was written the known natural exposures of
the sub-Aftonian were confined to a very limited area. A number
* of outcrops of this formation have since been recognized and
recorded, but it may be questioned whether the aggregate of all
the now known exposures of sub-Aftonian would be equal to more
than one or two square miles. Certainly there are no known areas
of anything approaching 200 miles in extent in which the lowest
of our drift sheets emerges from beneath anything so as to justify
its representation ona map. Other statements that can apply only
to what geologists have recently and consistently been calling Kan-
san occur on p. 757. The Kansan, we are told, “is greatly worn
in regions where the denuding agents have worked under favorable
Conditions seas 4.4. In other regions of flat surface and low declivity
the degradation is less marked, and extensive remnants of the
original surface-plane have been preserved.” The first super-
Aftonian drift fulfils the conditions of the parts of the text quoted
and of many others; the sub-Aftonian does not.

THE IOWAN DRIFT 581

While admitting, then, all that may be claimed for the frequent
references to the Aftonian soils, forests, peats, and gravels, it must
also be admitted that the descriptions in the early texts, which treat
of the texture, color, and petrological contents of the Kansan and
the Iowan, are based on observations made on two super-Aftonian
drifts. If there could remain a particle of doubt on this point after
reading the texts, the doubt would be dispelled by an examination
of the map opposite p. 727 of The Great Ice Age. The drifts of the
two areas represented as Kansan and Iowan respectively are both
super-Aftonian, and, considering the state of knowledge at the
time, the map is remarkably correct. The eastern edge of the
Iowan could scarcely be better drawn today. With the exception
of a few points which would be mere microscopic dots on a map of
this scale, the whole area mapped as Kansan is covered with super-
Aftonian till. There is not a single known natural outcrop of
sub-Aftonian in the Kansan area east of the Iowan margin. There
are no known outcrops of sub-Aftonian in Illinois, Missouri, or
northeastern Kansas where the map shows extensive areas of
Kansan. It is only very recently that the presence of sub-Aftonian
has been demonstrated in Nebraska; but even here it occurs in
vertical sections at the base of bluffs, in such position that it could
not well be represented on maps of moderate size. In Nebraska,
as in practically all the rest of the area mapped as Kansan, it is
a super-Aftonian drift that occupies the Kansan area on the map.
In all the earlier texts and maps it is a super-Aftonian drift to which
the name Kansan was most persistently and most consistently
applied.

EFFECTS ON TEXTS AND MAPS OF MAKING CERTAIN PROPOSED
CHANGES IN THE USE OF THE TERMS KANSAN AND IOWAN

As has been said, the imperfection of knowledge at the time the
Iowan and Kansan drifts were named led to confusion and incon-
sistencies of statements, and these are of such character and extent
as to make it now utterly impossible to apply the proposed names
in any conceivable way that will be in full accord with all the state-
ments of the texts. The frequent and positive references to the
horizon of the gravels and forest beds must be admitted and must
be given full weight in determining the particular drift sheets to

582 SAMUEL CALVIN

which the names Kansan and Iowan should be applied. On the
other hand, the original descriptions of the lower and upper till—
of the Kansan and the Iowan—must have careful consideration,
and the evidence of the map in The Great Ice Age, above cited,
must be taken into account. ~The descriptions would have to be
rewritten and the map redrawn to make them consistent with the
view that the Kansan is sub-Aftonian. If the term Kansan is
transferred to the sub-Aftonian, and the term Iowan to the drift
next above,’ practically the whole area represented on the map as
Kansan would have to be changed to Iowan. The Iowan would
then extend into southern Illinois, would cover southern and western
Iowa, northern Missouri, eastern Nebraska, and northeastern
Kansas. With the transfer of the term to the sub-Aftonian the
Kansan would be represented on the map by a few dots and thin
lines that could be seen only with the magnifier, the whole area
comprising an aggregate of only a few sections; and in the present
state of knowledge we could not be certain that Kansas has a cubic
foot of Kansan (sub-Aftonian) drift. We are face to face with the
fact that any application of the terms Kansan and Iowan involves
some inconsistencies, is at variance with some of the statements
in the original publications; and so long as we seem to need the
terms and have to use them, it is only a question of how to use and
apply them so as to do least violence to the original maps and
descriptions. If the map and descriptive texts referred to may be
taken as representing the intent of the authors, the practice of
applying the terms which has been followed, and which seems now
to come in for a certain amount of mild condemnation, is the only
one that is reasonably consistent or possible. For it must be
admitted that if the sub-Aftonian is to be called Kansan, and the
first super-Aftonian drift is to be the Iowan, more than nine-tenths
of the original descriptions are wholly erroneous and misleading,
and the map in The Great Ice Age showing the distribution of these
drifts is altogether meaningless and at variance with the facts.
Recent usage in the application of the terms Kansan and Iowan is
based on what seemed to be, and still seems to be, the only reason-

* Some such shift as this seems to be favored by what is said in the Journal of
Geology, July-August, 1910, pp. 473-74.

THE IOWAN DRIFT 583

able interpretation of what the authors had in mind when describ-
ing the physical characteristics of the two drift sheets and mapping
their areal distribution. A departure from this usage, which would
make the sub-Aftonian till Kansan and would apply the term Iowan
to the old, weathered till above the Aftonian, with its blue color,
its strikingly conspicuous array of greenstones, and with relations to
the loess so entirely different from the relations correctly described
in the text as pertaining to the Iowan, would necessitate the making
of radical and revolutionary changes in the map and descriptive
texts above noted. It surely accords better with what was pub-
lished at the time the names were applied to let recent usage remain
unchallenged and unchanged.

EVIDENCE CONCERNING THE IOWAN DRIFT AND ITS GEOLOGICAL
RELATIONS

The surprising attitude toward the Iowan drift, expressed
in the papers by Leverett, is something difficult to understand.
A very little field study in the right places will demonstrate:

1. The Iowan drift is.

2. The Iowan drift is young as compared with the Kansan.

3. The Iowan drift is not a phase of the Kansan.

4. The Iowan drift has very intimate relations to certain bodies
of loess.:

5. The Iowan drift is not related to the Illinoian.

Tue Iowan Drtrt Is

To discuss the question of whether there is an Iowan drift dis-
tinct from the super-Aftonian till that has been called Kansan is
like undertaking a task that one knows is absolutely useless and
unnecessary. For, while the Iowan is thin, and in places is absent,
there is here a very substantial drift sheet overlying the Kansan
and possessing distinctive characters of its own. The Iowan is
separated from the Kansan by a ferretto zone in some places and
by weathered gravels in others, while its characteristic topography
and remarkable bowlders proclaim its presence throughout exten-
sive areas where no sections are available. Buchanan gravels,
distributed by volumes of water from the melting Kansan glaciers,

584 SAMUEL CALVIN

and disposed in numerous sheets and ridges, were laid down
throughout northeastern Iowa, on top of the Kansan till, over the
area which, but a short time previously, had been abandoned by
the retreating ice. They are true outwash gravels. Exposure
during the long interval between the Kansan and the Iowan has
wrought profound changes in the decomposable granites and other

Ramee

Fic. 1.—View in the old gravel pit near Doris, Buchanan County, Iowa, showing
Buchanan gravels, a deposit contemporaneous with the closing phase of the Kansan,
overlain by the younger Iowan drift.

constituents of the Buchanan deposits; and now these gravel
deposits become unimpeachable witnesses to the fact that glaciers
belonging to a stage long subsequent to the Kansan distributed a
new sheet of till differing from the Kansan in composition, color,
and petrological contents. The Iowan is yellow; the Kansan,
while normally blue, sometimes weathers yellow; where yellow
Iowan rests directly on yellow weathered Kansan, the line of
contact may not be as distinct and satisfactory as some observers

THE IOWAN DRIFT 585

might wish; but where the Buchanan gravels intervene, the fact
that there is a drift younger than the Kansan and perfectly distinct
from it is as clearly indicated as that there are two drifts separated
by the Aftonian horizon.

Leaving out, therefore, all the evidence from the multitudes of
well sections and all other natural or artificial exposures that do
not show the intervening aqueous deposits, a few of the scores of
points where a young till overlies super-Kansan gravels may be

Fic. 2.—View in the same pit a few rods west of point shown in Fig. 1, taken while
work of excavation was in progress, showing the uneven line of contact between the old
gravels and the younger, overlying Iowan. The irregularity in the contact line may
be due to plowing or gouging by the Iowan ice.

cited. The best-known of these is the old Illinois Central gravel
pit near Doris in Buchanan County, a point that has been fre-
quently mentioned. Here are gravel beds with a maximum thick-
ness of fifteen feet or more. The deposit furnished many hundreds of
carloads of railway ballast annually for a number of years. In the
central part of the pit the gravel was taken out down to the blue
Kansan till, and balls of the same blue till are included in the
deposit. At the east end of the excavation there are at least ten
feet of yellow till above the gravel, recording a later, newer stage
of glaciation. The thickness of the later deposit is variable, for it

586 SAMUEL CALVIN

was laid down on an uneven surface; but at the point illustrated
in Fig. 1, the section of the till, including the black loam at the
top, is about eight feet. That the later and newer till is uncon-
formable on the gravel is shown in Fig. 2. The typical bowlders
of the Iowan drift belong to this overlying till; there is nothing
corresponding to them in the blue Kansan. In the process of
excavation a number of the Iowan bowlders were undermined and
allowed to fall into the pit. One such, perched on the brink of
the excavation, is shown in Fig. 3, and a larger-sized companion,
completely undermined, has fallen in. The typical, young, un-
eroded, bowlder-dotted surface of the younger drift, which stretches
away from the margin of the old working, is illustrated in Fig. 4.

A quotation or two from the report on Buchanan County, Iowa
Geological Survey, VIII, may be pertinent. On pp. 239-40 we read:

A very common relation of Pleistocene deposits is illustrated in the well

section on the land of J. W. Welch in the southwest quarter of Section 28,
Bufialo Township. The record shows:

Feet
25 Wark soilandiyellow tlle caso ce ee 4
2. Reddish, ferruginous sand and gravel.............. 23
iebluerclayapenctrated anc sci ieee eit aera e I

No. 3 of this section is Iowan drift, No. 2 is Buchanan gravel, and No. 1
is Kansan till.1 In the same quarter section another well shows,

Feet
Ze Soilandayellows tills eesess ere eran oe orerecreeeren ce ane 22
2aueddish pravelicco. ss wisace ween sete a ene ee ae ee II
t. Blue‘clay, with pockets of sande joss seen aes 19

Although the thickness varies considerably, the members of this last
section are severally the same as the corresponding numbers of the one above.

In another part of the same report, p. 209, it is recorded that
“the eastern part of Fairbank Township is a very level, dry plateau
in which a sheet of Iowan drift varying from two or three to thirty
feet in thickness overlies an extensive bed of Buchanan gravels.
The plateau is a unique piece of prairie land, without the usual
undulations, and without any indications of imperfect drainage.
The underlying gravel seems to afford an easy means of escape for
the surplus surface waters.”

* Owing to an error in proofreading the terms Iowan and Kansan are transposed
on p. 240 of the volume cited.

THE IOWAN DRIFT 587

Many similar cases could be cited, but it surely is not necessary
to multiply arguments in support of a fact that is so perfectly
obvious as the existence of the Iowan drift (Figs. 1 and 2). There
is no sheet of till that has more distinctive characters, more definite
stratigraphic relations. A glacial deposit showing thicknesses of
4 feet, ro feet, 22 feet, 30 feet, a deposit with distinctive bowlders
of enormous size, a deposit that is young, fresh, uneroded, and
separated from the Kansan by a weathered ferretto zone and pro-
foundly altered gravels, is certainly a very real and substantial

Fic. 3.—View in the Doris gravel pit, showing undermined Iowan bowlders;
one is still perched on the brink of the excavation; the larger companion has fallen
into the pit. _

thing that may not be disposed of by referring to it as ‘‘only the
weathered surface of a drift,” or by the use of such a qualifying
phrase as “so-called Iowan.”

That there are two gravel horizons in this region—one Aftonian,
the other Buchanan, one below the blue Kansan drift, the other
above it—is indicated by two wells near the northwest corner of
Section 22, Buffalo Township, Buchanan County. One of the
wells, 152 feet deep and ending in gravel (Aftonian) which lies
beneath the Kansan, furnishes a constant stream of water an inch
in diameter; the other, which is not flowing, is 25 feet deep and
ends in a bed of Buchanan gravel which overlies Kansan.

588 SAMUEL CALVIN

From the other counties included in the Iowan area comes
evidence of the distinctive character of the Iowan drift similar to
the evidence from Buchanan. Probably the banner county in Iowa
for inter-Kansan-Iowan gravels is Floyd. Here are scores of
exposures, occupying every conceivable position from the flood
plains of the streams, like the Little Cedar, the Cedar, and Flood
creeks, which carried off the waters from the melting Kansan ice,
to the highest points on the broad, monotonously level, uneroded
divides; and in every case within the Iowan area where these old,
weathered gravels are known to be present; they are overlain by
deposits indicating a much later and newer glacial episode. It will
be sufficient to note only a few of the numerous cases which have
been observed. At the old brickyard west of the fair-ground in
Charles City the material used was a five-foot bed of loam and
yellow clay carrying Iowan bowlders four to five feet in diameter,
and overlying the valley phase of the Buchanan gravels, which,
in the neighborhood of Charles City, attain an enormous develop-
ment. For some miles above Charles City, on the west side of
the Cedar River, the old valley gravels may be seen passing under
a thin bed of young, bowlder-bearing loam and clay which covers
the gentle slopes and passes up over the flat divides. A boring
with a post auger within the bowlder-strewn area went through the
thin edge of the Iowan loam into the underlying gravels. The
holes dug for some recently set telephone poles along the road and
a small stream trench some distance up the slope in the field show
the same relation of bowlder-bearing loam to the Buchanan beds.
A young glacial deposit overlies super-Kansan gravels; at one
point in the trench the gravels rest on the blue Kansan till.

The same story is told, though in a slightly different way, by
the majority of the many ‘‘mound springs” of this part of Iowa.
Mound springs are peaty, boggy places on the hill slopes, due in
most cases to the presence of upland gravels lying on impervious
blue Kansan, and all covered by the younger sheet of Iowan. The
gravels in such cases are reservoirs holding large quantities of water,
and this escapes on the slopes near the plane of contact between
the reservoir and the underlying clay at the point where the con-
ditions are most favorable, presumably where the Iowan cover is

THE IOWAN DRIFT 589

thinnest. The dry upland slopes above the level of the peat, as
well as the dry slopes below that level, are liberally sprinkled with
Iowan bowlders imbedded in loam and clay and ranging up to more
than 12 feet in diameter. These bowlders are in themselves ade-
quate evidence of a glacial invasion at a time subsequent to the
gravel-forming phase, for they were not transported and deposited
by either wind or water.

Fic. 4.—View looking north from the margin of the Doris pit, showing the young,
uneroded, bowlder-strewn Iowan drift plain; a very typical view in the area occupied
by this young drift. :

Typical examples of mound springs, easily accessible from
Charles City, and showing the stratigraphic relations of Kansan,
Buchanan, and Iowan deposits, occur on both sides of the railway
in the north half of Section 2, Township 95, Range 15. Preliminary
to laying a water pipe from the springy belt to the barn on the land
of Mr. W. E. Waller, south of the railway, a shallow well was dug
on the dry ground just above the peat; and this passed through
the cover of Iowan bowlder-bearing loam and clay, and through
the thinned edge of the rusty gravels, down far enough to make a
water-tight basin in the blue Kansan. A deeper well near the
barn, with 12 feet of gravel and 60 feet of blue clay, may be cited

590 SAMUEL CALVIN

to show the constant relation of the prevailing gravels of the region
to the typical Kansan drift. The same relation is shown in the
fine Pleistocene section which occurs a few rods north of the Mitchell
County line, not far from the southwest corner of Section 14,
Township 97, Range 17. Here, in the south bank of Rock Creek,
is an exposure of typical Kansan, blue in color and breaking into
the characteristic polyhedral blocks, with an exposed thickness of
50 feet; at the top is a discolored, weathered zone three to four
feet thick; next in order is a gravel bed, rusted and rotted, thick-
ness about two feet; and all is covered by a thin loamy deposit
carrying many fresh bowlders of varying size, belonging to a post-
Buchanan stage of glaciation—the Iowan.

But it is certainly unnecessary to offer additional evidence along
this line. Cases of the kind already cited may be multiplied
indefinitely. Fortunately the Buchanan gravels are especially
well developed in northeastern Iowa, and in the Iowan area they
uniformly afford indubitable evidence of a younger, newer, later
stage of ice invasion. Outside the Iowan area, as at Colesburg,
Delaware County, on the east, and at Iowa City on the south, the
Buchanan gravels are covered with heavy deposits of loess, and
without the least suggestion of later glaciation. ‘Some very impor-
tant event, later than the deposition of the gravels, an event which
caused the deposition of a body of till ranging up to 20 or 30 feet
in thickness and carrying bowlders more than 12 feet in diameter,
occurred within the Iowan area and did not occur outside of it.
What was that event? Observations in and around the area lead
unavoidably to but one conclusion, a conclusion that admits of
no question:

The Iowan drift 1s.

Tue Iowan Drirt Is YouNG AS COMPARED WITH THE KANSAN
The superposition of the Iowan till and the great Iowan bowlders
on the weathered Buchanan is all the evidence needed to demon-
strate that the Iowan is younger than the Kansan. The freshness
of thé granites in and on the Jowan—many with the sharp angles
caused by fracture unaffected by weathering (Fig. 10), while the
granites of the Buchanan are very largely in an advanced stage of

THE IOWAN DRIFT sol

decomposition—lends strong support to the view that the Iowan
is separated from the Kansan by a very long interval of time.
The relative youth of the lowan may, or may not, be indicated
by the fact that in places the formation is still very calcareous up
to the grass roots. A concrete illustration of calcareous Iowan is
seen in a shallow well near the northwest corner of the southeast
quarter of Section 21, Township 95, Range 17. It should be stated

Fic. 5.—View at the Dykeman quarry in Section 26, Township 97, Range 17,
showing part of an area of thin drift, in which neither Iowan, Kansan, nor Nebraskan
can be recognized.

that the later investigations show that this young drift is variable
as to the amount of the lime content; for in such localities as that
just cited it seems to be as rich in calcium carbonate as the Wis-
consin, while in other places it gives no reaction with acid. The
original statement concerning this constituent of the Iowan drift
was based on facts which remain true for the localities which had
then been tested; but the writer has long since ceased to attach
much importance to the acid test as a basis for determining the

592 SAMUEL CALVIN

relative age of drift. The splendid piece of work by Dr. R. T.
Chamberlin in the St. Croix region’ shows how a very young
drift may exhibit no trace of lime, while a much older one may give
vigorous reactions. In each and every case the amount of calcium
carbonate present at or near the surface of a deposit of drift will
depend on the original composition of the till and the movements
of the ground waters. The same drift sheet gives very different
reactions in different localities. The work in Taylor County in
t1g10 showed very large quantities of lime carbonate in the form
of segregated sheets and nodules, distributed along the joints in
the highly weathered zone of the old Kansan. The lime came
practically to the surface and was turned up among the grass roots
by the plow. Along the roadsides, where the highway had been
recently worked, it was breaking down to powder and mixing with
the crumbling clay; and a sample of the old drift taken at the very
surface might have given such energetic reactions to the man with
the acid bottle as to lead him to think that he was dealing with the
youngest glacial deposit in Iowa. Just why it is that both the old
Kansan and the young Iowan should be so very calcareous up to
the grass roots in some localities, while showing no traces of lime
in others, could be explained, in some cases at least, on the basis of
physical characteristics and relation to surface and sub-surface
drainage; but it will be sufficient here simply to record the fact
and repeat the obvious inference that acid tests applied to drift
sheets are of exceedingly small importance in the determination
of relative age. The acid bottle, intelligently used, has its place;
but the user must be careful to recognize its limitations. :
Among the evidences of youth in the Iowan drift is the fact that,
in its typical areas, it is uneroded and imperfectly drained. The
area selected for illustration in Fig. 7 of the article from the A meri-
can Journal of Science, and again in Fig. 5 of the paper reprinted
from the Zeitschrift fiir Gletscherkunde, and offered as “the type of
erosion”’ in the Iowan drift or as something ‘‘showing topography
of a so-called Iowan drift plain,” is a somewhat unfortunate and
misleading choice for the reason that it is representative of but a

‘ Rollin T. Chamberlin, “‘Older Drifts in the St. Croix Region,” Journal of Geology,
XVIII, No. 6, September-October, 1910.

THE IOWAN DRIFT 593

small fraction of the real Iowan drift plain. It embraces the
headwaters of Otter Creek, the valley of which belongs to one of the
numerous small, exceptional areas in which there is no drift of any
kind, neither Nebraskan, Kansan, nor Iowan. Within the southern
edge of the map, and at Hazelton, less than a mile farther down the
valley, the Niagara limestone is exposed in natural cliffs or quarry
faces, forming continuous exposures along the streams in Sections

Fic. 6.—View taken east of the diagonal road in Section 28, Township 95, Range
15, showing typical driftless hills in the belt of country west of the Cedar River.

2 and ro of Hazelton Township. A part of Section 2 is included in
the map. There are outcrops below the village of Hazelton; and
in the roads on the sloping sides of the valley, up to the summit
of the slopes, rain, wash, and wear of traffic have exposed the fos-
siliferous Niagaran dolomite, so thin and meager is the Pleistocene
in this anomalous area. A full discussion of the Niagaran outcrops
in this practically driftless valley will be found on pp. 217-20,
Iowa Geological Survey, VIII, published 1898. Describing one of
the quarries in Section 10, the report says: ‘‘The height of the

5904 SAMUEL CALVIN

vertical quarry face is about fourteen feet. The upper two or
three feet is made up of soil, reddish-brown residual clays, and
decayed fragmentary limestone.” It will be noted that there is no
recognizable drift; and if the area mapped is to be used to prove
that there is no Iowan, with equal force, fairness, and cogency
certain parts along its southern margin, together with the whole

Fic. 7.—View on north side of the road passing through the middle of Section 21,
Township 84, Range 18, showing the marly, fossiliferous phase of the Lime Creek
shales at the surface, with no overlying drift of any age.

valley of Otter Creek southward, might be used to prove that there
are no glacial deposits of any sort within the whole state of Iowa.
It would be possible to select a great many points within the
Iowan area, that are driftless or practically so, where Pleistocene
deposits are wholly absent or are represented by thin beds of sandy
loam or a few stray bowlders. One such begins in the eastern edge
of Independence and extends eastward over the stony hills for more
than a mile. This is part of a belt some miles in length bordering

THE IOWAN DRIFT 595

the Wapsipinicon River. The valley of the Cedar River, the
anomalous characteristics of which are recognized and noted, if
not explained, in Jowa Geological Survey, XIII, 298, 306, affords
numerous examples (Figs. 5, 6). For some unaccountable reason
the parts of the state occupied by the Lime Creek shales have an
unusual number of driftless patches, some of which have dimensions
of several miles. A rather small, but typical area of the kind occurs

Fic. 8.—View on ridge in Section 3, Washington Township, Chickasaw County,
Towa, showing the largest bowlder in the county rising out of a heavy growth of small
grain.

in Section 21, Township 84, Range 18 (Fig. 7). Large areas,
almost continuous, occur over the ten-mile stretch between Mason
City and Rockwell; and on the south side of Lime Creek there is a
belt, practically driftless, two or three miles wide, all the way to
Rockford. There may be bowlders in these areas, even where the
other constituents of the drift are absent; and in no small propor-
tion of the territory under consideration, ‘‘the soil through which
the farmer drives his plow is made up of decomposed shales of

596 SAMUEL CALVIN

Devonian age.” The collector may gather Lime Creek fossils in
the pastures and cultivated fields. The peculiarities of these
areas, so far as they are seen in Cerro Gordo County, are noted in
Iowa Geological Survey, VIII, 175, where, years ago, the statement
quoted was published.

With the exception of the sub-Aftonian, or Nebraskan, which
does not give character anywhere to parts of the glaciated territory
large enough for mapping, each drift sheet has its characteristic
topography which prevails over the major part of its area, and each
has its exceptional phases which affect but a small percentage of
its surface. There is a broad belt of typical Iowan between the
Wapsipinicon and the Cedar, north of Walker. With the exception
of a narrow strip west of the larger river, the broad area between
the anomalous Cedar and Flood creeks in Mitchell, Floyd, and
Franklin counties is as strikingly level, uneroded, and free from
drainage courses as much of the typical Wisconsin, and in some
places it is also quite as calcareous. Flood Creek is simply a prairie
stream that scarcely breaks the monotony of the plain that extends
from the Cedar to the Shell Rock; through its entire course north
of Nora Springs, even the Shell Rock flows in a young, shallow
trench cut in the otherwise unbroken Iowan plain. Areas such as
these—scores of miles in length and width, with scarcely a drainage
trench outside the channels of the larger streams—illustrate the
real type of erosion in the Iowan; these show the topography of a
real Iowan drift plain, and it is scarcely necessary to add that that
topography is characteristic of youth.

The typical bowlders of the Iowan are coarse feldspathic
granites in no way remarkable for their power to resist the destruc-
tive agencies of weathering, and yet very little decomposition has
taken place amongst them since they were left exposed at the time
of the retreating Iowan ice. In some way, either before or during
transportation, many of the bowlders were fractured, and in such
cases the angles are still comparatively sharp (Fig..10), while bowl-
ders of corresponding texture in the Buchanan gravels or in the
weathered zone of the Kansan drift are completely decayed.
Topography, bowlders, and stratigraphic position all unite in
support of the theses:

THE IOWAN DRIFT 507

The Iowan drift is young as compared with the Kansan.

The Iowan drift is not a phase (weathered or unweathered) of the
Kansan.

The statement on p. 282 of the paper on “‘Comparison of North
American and European Glacial Deposits,” to the effect that the
Iowan bowlders ‘‘are found chiefly in shallow draws, called sloughs,

Fic. 9.—View in Section 14, Township 95, Range 16, showing a fresh, planed
bowlder of the Iowan type in a dry, cultivated field.

at the heads of the valleys or drainage lines,” has no special signifi-
cance even if it were fully justified; but the fact is that the Iowan
bowlders occur in various relations to the rather featureless topog-
raphy of the region to which they are confined. The largest mass
of granite in Chickasaw County is on the highest ridge of the whole
region, midway between Devon and Alta Vista. There are three
Iowan bowlders in Floyd County especially noted for their com-
manding size, and each is located on dry upland. One of these
(Fig. to) occurs less than two miles southwest of Charles City, in
the northwest quarter of Section 14, Township 95, Range 16. It

598 SAMUEL CALVIN

lies in a cultivated field on the long gentle slope above the road
which follows the north line of the section. The dimensions above
ground are 27X21X1r feet. Some of the faces are surfaces of
fracture, and the angles remain sharp and unaffected by weather.
A fragment of smaller size, evidently split off from the larger mass
during the time of transportation, equally fresh as to angles and

Fic. 10.—View in Section 14, Township 95, Range 16, showing one of the largest
and most typical of the Iowan bowlders on dry ground, with sharp angles unaffected
by weathering.

general surface, lies a few rods to the northeast. A very fine
bowlder (Fig. 11), more massive than the Charles City specimen,
unbroken in transportation, lies near the southeast corner of the
city park in Nora Springs, and there are neither “‘draws”’ nor
“sloughs” anywhere near it. Probably the largest bowlder in the
state, the largest so far recorded, occurs in a dry pasture near the
southwest corner of Section 22, Township 94, Range 15 (Fig. 12).
It is more than forty feet in length, a block of characteristic Iowan

THE IOWAN DRIFT 599

granite of royal proportions. In some parts of the Iowan area,
notably in the region between the Cedar and Little Cedar east of
Charles City, the bowlders are distributed in trains which stretch
across the country from northwest to southeast without respect to
sloughs, while intervening spaces of essentially the same topography
are practically free. The fact is, however, that the bowlders may
be anywhere; upland or lowland seems to make no special differ-

Fic. 11.—View in Nora Springs, Iowa, showing a large and very typical Iowan
bowlder on dry upland, near the southeast corner of the city park.

ence; their distribution follows no constant rule, except one:
typical Iowan bowlders are strictly limited to the area of the Iowan
drift.

THe Iowan Drirt HAs CERTAIN VERY INTIMATE RELATIONS TO CERTAIN
Bopies oF LOESS

The discussion of the loess and of Calvin’s attitude toward it,
on pp. 298-99 of the Berlin paper, is based on so many misappre-
hensions that the task of straightening out the tangle is one too
hopeless to be undertaken. There are bodies of loess belonging to
different ages, but there is one loess that stands in intimate and
close relation to the Iowan drift. The view that the loess is chiefly

600 SAMUEL CALVIN

an interglacial deposit is in no way inconsistent with the earlier
view—and the view still entertained so far as the source of the
deposit is concerned—‘‘that the loess is a. silt derived from the
finer materials of the Iowan drift.” That a certain deposit of
loess was derived from the Iowan is a conviction that grows stronger
and stronger as the work is prosecuted farther and farther in the

Fic. 12.—View near the southeast corner of Section 22, Township 94, Range 15,
showing what is probably the largest Iowan bowlder in the state; and this lies in a
dry pasture.

field; and outside the paper under consideration there has never
been any ‘“‘abandonment of the view that there is an Iowan drift
correlating with the loess.”’

The Buchanan gravels are an interglacial deposit. They are
not of glacial origin, and they lie between two sheets of drift. The
fact that they are interglacial, however, gives no adequate ground
to infer that they were not derived from the Kansan, or that there
has been an abandonment of the view that there is a Kansan

THE IOWAN DRIFT 601

drift correlating with the Buchanan gravels. The Iowan loess is
related to the Iowan drift in much the same way that the gravels
are related to the Kansan. The earlier view was that the loess
was deposited at the time of. maximum development of the Iowan
glaciation, when the Iowan area was still covered with ice. The
only modification of that view at the present time is that loess
deposition took place after the Iowan ice had retreated to a greater
or less extent, after an interglacial interval had actually begun.
By such retreat extensive mud flats were left, and as these dried
before becoming covered with vegetation, strong winds coming,
probably, from the ice fields to the north, carried fine sand and dust
from the bare surfaces and deposited them beyond the edge of the
Iowan area, out upon the old, eroded Kansan. For the development
of loess three things seem to be necessary: (1) a gathering-ground
of extensive bare and dry surfaces, such as would be furnished
by the part of the Iowan area from which the ice had retreated;
(2) winds to transport the materials from the dried mud flats; (3)
anchorage such as would be furnished most extensively by the
vegetation of the extra-marginal Kansan surface. The bare Iowan
area afforded no anchorage, but it was an excellent source of supply.
Waters carried and sorted materials from the Kansan till and
deposited the interglacial formation called Buchanan gravels; winds
picked up from the Iowan till such materials as they could trans-
port, and deposited amidst the vegetation of the extra-marginal
territory the interglacial formation known as the Iowan loess.
The genetic relation of the loess to the Iowan drift is not so very
unlike the corresponding relation of the Buchanan gravels to the
Kansan; and so far as genetic relationships are concerned, there has
been no abandonment of the view originally proposed.

The color, composition, and calcareous content of the Iowan
loess are in perfect accord with the hypothesis just expressed; its
geographic distribution around the lobed margin of the Iowan area
agrees also with the view; the great thickness of this loess at and
near its inner margin, and its thinning out with increasing distance
from the source of supply, corroborate all the other lines of evidence;
while the great amount of eolian sand associated with it in a narrow
belt surrounding the lobes of Iowan drift lends additional support.

602 SAMUEL CALVIN

The Missouri River loess and all other loess deposits which have
evidently been derived from the broad flood plains of near-by
rivers, have a similar distribution relative to their source; they are
thickest and coarsest near the gathering-ground and become
thinner as the distance from the base of supply increases. All
the facts connected with the origin, composition, and distribution
of the loess are perfectly explicable without resorting to the
hypothesis that “‘a considerable part’ was derived from the great
plains east of the Rocky Mountains.”’ Studies in the field afford
overwhelming evidence that, genetically and geographically, the
Iowan drift has very intimate relations to certain bodies of loess.

Tue Iowan Drirt Is Not RELATED TO THE ILLINOIAN

It is scarcely necessary to discuss the suggestion that the lowan
may be correlated with the Illinoian. Parenthetically it may be
said that if the Iowan and the Illinoian represent the same stage
of glaciation, the name IIlinoian becomes a synonym for lowan, and
we shall be reduced to the painful necessity of referring to one of
our most beloved drift sheets as the “‘so-called Hlinoian.” But
no such calamity awaits the Illinoian. The Iowan is much the
younger of the two. As indicated by the structural and genetic
relations above noted, the Iowan —a little later probably than its
maximum stage—is practically contemporaneous with the loess;
and as the Berlin paper, with noteworthy lucidity, correctly states
on p. 299; “the Sangamon interval separates the loess from the
Illinoian stage of glaciation so widely that there would seem to be
no relation between loess deposition and Ilinoian outwash.” The
same long interval, the same wide separation, exists between the
Iowan and the Illinoian stages of glaciation. The two drifts are
not related in time or in any other way. All the facts which may be
gathered from the most thorough investigations in the field, support
this last proposition:

The Iowan drift 1s not related to the Illinotan.

THE THEORY OF ISOSTASY

HARMON LEWIS
University of Wisconsin

TABLE OF CONTENTS

SECTION I. INTRODUCTION

General
Definitions

Section IJ. THE Greopetic Work oF JOHN F. HAyForp

Brief Description of His Work and Methods
Criticism of Hayford’s Work
Criticism of method of finding degree of completeness of compensation
Criticism of C-solution
Further Considerations
Possibilities of an incomplete compensation
Changes in formulae required by shallow depth of compensation
Summary

SecTIon III. Tue TuHrory or Isostasy

Introductory
Type of deformation postulated in the theory of isostasy
Lines of criticism of isostasy
Facts not Accounted for by the Type of Deformation Postulated in the
Theory of Isostasy
The theory of isostasy as conceived in this paper does not adequately
account for the folding of rocks of the earth’s crust
The theory of isostasy cannot account for the general uplift of sedi-
ments without folding
The theory of isostasy does not explain the apparently heterogeneous
relation of uplift and subsidence to erosion and deposition
Alternative Hypotheses to Account for Hayford’s Geodetic Results
The tendency of lateral compression to produce isostatic compensa-
tion
The automatic compensation of uplifts and subsidences due to expan-
sion and contraction

SECTION IV. SUMMARY OF CONCLUSIONS
603

604 HARMON LEWIS

SECTION I. INTRODUCTION
GENERAL

According to the present general conception the theory of
isostasy consists of two main postulates, first that the elevated
portions of the earth are deficient in density, and second that the
material of the earth is comparatively weak. It is generally ac-
cepted that these two postulates are inseparable, for it is argued
on the one hand that, if the elevated portions are deficient in
density, readjustment involving deformation and failure must have
taken place in order to compensate for the large mass of material
eroded from the lands and deposited in the sea; and it is contended
on the other hand that, if the earth is weak, it could not support
the mountains and continents unless they are compensated by a
defect of density below. In accordance with these two main postu-
lates it is conceived that the dominant type of earth deformation
consists in vertical movements between various segments accom-
panied by lateral flowage of rock beneath and possibly crumpling
of the rock in the border zones. This conception is not only applied
to the major earth segments, the continents and oceans, but to
the smaller units of the continents as well.

The theory of isostasy is a decided contrast to the alternative
conception that the earth is strong enough to support the continents
and mountains even though there are no compensating density
differences, that changes of weight at the surface do not produce
vertical movements of the segments in a weaker substratum, and
that the dominant type of deformation is folding and upwarping
due to lateral compression.

The theory of isostasy if correct would be of fundamental impor-
tance to the geologist in interpreting earth movements.

Previous to Hayford’s geodetic investigation the conceptions
of isostasy were largely speculative. After a comprehensive study
of the deflections of the plumb bob carried out by the United
States Coast and Geodetic Survey under Hayford’s direction,*

«The most complete statement of Hayford’s work which has been published is
contained in his two reports issued in 1909 and 1o10 by the U.S.C. and G.S. and

entitled, The Figure of the Earth and Isostasy from Measurements in the United States
and Supplementary Investigation in 1909 of the Figure of the Earth and Isostasy.

THE THEORY OF ISOSTASY 605

the rather startling conclusions were reached that the excesses
of mass composing the continents and mountains are completely
compensated by deficiency of density below and that this deficiency
of density extends to a depth of something like 60 to 150 miles.
These conclusions lent strong support to the theory of isostasy.
Considering the completeness of the density compensation, there
seemed to be no escape from the conclusion that readjustments
of the nature postulated by isostasy are continually taking place.

With the theory of isostasy apparently on such a firm basis,
Hayford and others have elaborated the conceptions of earth move-
ments involved in the theory, but these further inferences have not
met the approval of many geologists.

The possibility that Hayford had made an error in his geodetic
work suggested an investigation which is the basis of this paper.
The attempt has been made, first, to examine Hayford’s geodetic
work apart from any inferences which may have been drawn from
it, and second, to examine the theory of isostasy with reference
to inferences from geodetic evidence and also on general grounds.
This paper has accordingly been divided into two main parts
entitled ‘‘The Geodetic Work of John F. Hayford” and “The
Theory of Isostasy.” A ‘‘Summary of Conclusions” is given at
the end.

It seemed highly desirable in connection with the criticism of
Hayford’s geodetic work that several of the terms employed
should be defined.

DEFINITIONS

““*Tsostatic compensation’ is the compensation of the excess of
matter at the surface (continents) by the defect of density below, and
of the surface defect of matter (oceans) by excess of density below.”
““Tsostatic compensation’’ will also be referred to simply as ‘‘com-
pensation”? and an area or segment of the earth will be spoken of
as “‘compensated”’ if there is isostatic compensation of the excess
or defect of matter over that area or at the surface of the given
segment. From the above definition it follows that there will be,
in general, a density difference between an average sea level segment

t The Figure of the Earth and Isostasy, U.S.C. and G.S., 1909, p. 67.

606 HARMON LEWIS

of the earth and a compensated segment, the surface of which is
not at sea level. This density difference will be called the “compen-
sating density difference.”

The ‘depth of compensation” for any segment of the earth 1s the
greatest depth below sea level at which there is a compensating density
difference. This is different from the definition of Hayford which
makes the ‘“‘depth of compensation”’ the depth ‘‘ within which the
isostatic compensation is complete.” The former definition allows
for the possibility of a compensation which is not complete.

The ‘distribution of compensation”’ for any segment of the earth
is the manner of variation of the compensating density difference with
respect to depth. If the compensating density difference is uniform,
the distribution of compensation is uniform; if it is uniformly
varying from a maximum at the surface to zero at the depth of
compensation the distribution of compensation is uniformly
varying.

The ‘‘degree of completeness of isostatic compensation”’ is
an expression used by Hayford. After defining the depth of com-
pensation as quoted above, he says, ‘‘At and below this depth the
condition as to stress of any element of mass is isostatic; that is,
any element of mass is subject to equal pressures from all directions
as if it were a portion of aperfect fluid. . . . . In terms of masses,
densities, and volumes, the condition above the depth of compen-
sation may be expressed as follows: The mass in any prismatic
column which has for its base a unit area of the horizontal surface
which lies at the depth of compensation, for its edges vertical lines
(lines of gravity) and for its upper limit the actual irregular surface
of the earth (or sea surface if the area in question is beneath the
ocean) is the same as the mass in any other similar prismatic column
having any other unit area of the same surface for its base.” This
condition of course follows from Hayford’s definition of depth of
compensation, but it would not hold for the definition adopted in
this discussion unless the compensation were complete. Hayford
continues as follows: “If this condition of equal pressures, that is,
of equal superimposed masses, is fully satisfied at a given depth
the compensation is said to be complete at that depth. If there
is a variation from equality of superimposed masses the differences

THE THEORY OF ISOSTASY 607

may be taken as a measure of the degree of incompleteness of com-
pensation.’’’ In order to make this idea exact, let A and B (Fig. 1)
represent two columns each of horizontal cross-section, a, and
extending to the depth of compensation, /,, the upper surface of A
being # miles above sea level and

the upper surface of B being at sea os

level. Let the weight of A equal sea leve/
Wa, and the weight of B equal Wz. y

If there were no isostatic compensa-

tion, and if the densities of A and B

were the same at similar depths, then

Wa would be in excess of Wz by the h,
amount adh, where 6 is the mean

surface density of the earth. If this

excess of weight were entirely made

up for by a deficiency of density

below, compensation would be com- A 2S pee

plete. Therefore let the “degree of
completeness of isostatic compensation”? for any segment, A, be
defined as

_ adh—(Wa—WsB)

ul aoh

The quantity in parenthesis is the amount by which the weight of A
is in excess of the weight of B. The whole numerator is, therefore,
the weight which has been made up for by a deficiency of density
below the surface and the entire fraction is a number expressing the
part of the weight, a5, which has been made up for. The above
formula holds equally well for land and ocean areas if h be taken
positive above sea level and negative below.

FOR LAND AREAS

Teelit Wa< We then M>1
De AGE Wa=Ws then M=1
3. If Wa—Wp=aoh then M=o
4. If Wa—We>abdh then M<o

t The Figure of the Earth and Isostasy, tgceg, p. 67.

608 HARMON LEWIS

FOR OCEAN AREAS (/ BEING A NEGATIVE QUANTITY)

1. If Wa>Wes then M>1
2 ht Wa=We, then M=1
3. If Wa—Ws=adh then M=o
4. If Wa—Wa< adh then M<o

When M=o, there would be no isostatic compensation. The
condition that M is negative is equivalent to a distribution of den-
sity so related to the surface that the material under any surface
is heavier than the material under a lower surface. There would
be no isostatic compensation in this case. In view of the facts
brought out by Hayford the fourth case is, however, very improb-
able.

‘““Over-compensation”’ is such an isostatic compensation that
M >t.

‘““Complete compensation”’ is such an isostatic compensation
that M=1.

‘“‘Under-compensation”’ is such an isostatic compensation that
On Ey

Isostatic compensation is considered the more complete, the
closer M approaches to 1.

SECTION II. THE GEODETIC WORK OF JOHN F. HAYFORD
BRIEF DESCRIPTION OF HIS WORK AND METHODS

On certain assumptions as to the size and shape of the earth and
as to the position of a base station on this ideal earth, Hayford,
by triangulation and geodetic observations, measured the prime
vertical and meridian components of the deflection of the plumb
bob from the true vertical at several hundred stations scattered
over the United States. He then calculated the deflections which
all the topographic features within a radius of 2,564 miles of each
station should produce if the density of the earth were the same at
similar depths. He found that these calculated deflections, which
he called the “topographic deflections,” were universally larger
than the “observed deflections.” The only explanation of such
widespread observations is that there is some sort of isostatic
compensation of the surface excesses and defects of mass. Recog- _

THE THEORY OF ISOSTASY 609

nizing this fact Hayford set out to make a series of least square
solutions assuming various kinds of isostatic compensation. He
calculated what the deflections should be assuming isostatic
compensation by the use of a reduction factor, that is, a factor
which when multiplied by the topographic deflection will give the
deflection, isostatic compensation considered. In all of his solu-
tions Hayford assumed the isostatic compensation to be complete.
In his five principle solutions he assumed a uniform distribution of
compensation and assumed depths of compensation varying from
zero to infinity.7 On these assumptions the conclusion was reached
that the most probable depth of compensation is 76 miles since
the sum of the squares of the residuals was least for this depth.

Subsidiary solutions were made assuming (1) that the compen-
sation is uniformly distributed in a ten-mile substratum, (2) that
the compensation is greatest at the surface and decreases uniformly
with respect to depth until it becomes zero at the depth of compen-
sation, and (3) that the compensation is distributed according to
the law postulated by Chamberlin.?, The method used in each of
these three cases was to find the depth for which the reduction
factor was most like the reduction factor for the most probable
solution assuming a uniform distribution. Hayford concluded
that so far as the geodetic evidence available could test them, any
of the three distributions of compensation postulated is as probable
as a uniform distribution. The depth of compensation found for
a distribution in a ten-mile substratum was 4o miles; for a uni-
formly varying distribution, 117 miles; and for the Chamberlin
distribution of compensation, 193 miles.

A further interesting phase of Hayford’s work is his C-solution3
which was made on the assumption that there is no isostatic com-
pensation under land areas but that there is complete isostatic

™ The condition that the depth of compensation is infinite is taken as equivalent
to no isostatic compensation. The condition that the depth of compensation is zero
is taken as equivalent to the condition that the topographic features do not affect the
plumb bob.

2 This law postulates a maximum density difference slightly below the surface.
This density difference decreases rapidly at first and then more gradually with respect
to depth.

3 P. 168 of 1909 report.

610 HARMON LEWIS

compensation at depth zero under ocean areas. It was found that
these assumptions were not as close to the facts as the assumption
of complete compensation at the depth of 76 miles under both
land and ocean. In discussing the C-solution Hayford says:

It follows, moreover, that it is an isostatic compensation of the separate
topographic features of the continent, not a compensation merely of the conti-
nent asa whole. In solution A? it is a compensation of the separate features
which is assumed. An inspection of the numerical values of the computed
topographic deflections, and of the deflections computed with isostatic com-
pensation considered shows that merely to have assumed the continent as a
whole to be compensated, not its separate topographic features would have
given a solution resembling solution C much more closely than solution A.3

A very vital step in Hayford’s work is his determination of the
degree of completeness of compensation. As this is one of the
principal points to be criticized, his method will be explained in
detail in connection with the criticism. Suffice it to say here that
he concluded that the isostatic compensation is on an average nine-
tenths complete.

CRITICISM OF HAYFORD’S WORK

Hayford certainly showed that there is some sort of isostatic
compensation; but he did not fully consider all possibilities as to
the nature of this compensation. The exact nature of isostatic
compensation for any place is determined by three factors, (1) depth
of compensation, (2) distribution of compensation, and (3) degree
of completeness of compensation. Hayford considered all possible
depths of compensation and several distributions of compensation;
but all of his solutions involving isostatic compensation were made
on the assumption that the compensation is complete. This was a
purely arbitrary assumption on Hayford’s part since he gave no
reason whatever for believing at the outset that compensation is

‘Quoted from p. 169 of 1909 report.

2 Solution A was made on the assumption that compensation is complete at depth
zero over both land and sea. This solution turned out to be nearer the truth than
solution C.

3It should be noted that the assumption of complete compensation under ocean
areas with no compensation under continents is not equivalent to a compensation of
the continents as a whole with respect to the oceans, but only to a compensation for
the part of the continents below sea level.

THE THEORY OF ISOSTASY 611

complete, and furthermore the fact that he later attempted to find
the degree of completeness implies that there is no reason to believe
at the outset in complete compensation. In view of this fact the
method of determining the degree of completeness of compensation
is questionable.

Criticism of method of finding degree of completeness of compen-
sation.—Hayford’s method is best explained by an example. Sup-
pose the topographic deflection at some station is 35.79” This
is assuming no isostatic compensation. Suppose that the residual
assuming complete compensation at a depth of 76 miles is 3.33”,
or in other words, suppose that the difference of the true deflection
and the deflection which would exist if the compensation were
complete at a depth of 76 miles is 3.33” This value (3.33”) is
apparently the part of the topographic deflection which has not
been made up for by isostatic compensation. The ratio of 3.33
to 35.79 is, therefore, taken by Hayford as a measure of the incom-
pleteness of compensation. In explanation of this method Hayford
writes as follows: .

The residuals of solution Gt furnish a test of the departures of the facts from
the assumed condition of complete isostatic compensation uniformly distri-
buted to a limiting depth of 113.7 kilometers. In order to obtain definite
ideas let the whole of the residuals of this solution be credited to the incomplete-
ness of the compensation. The conclusion as to the completeness of compen-
sation will then be in error in that the actual approach to completeness will
be considerably closer than that represented by the conclusion—that is, the
conclusion will be an extreme limit of incompleteness rather than a direct
measure. For by this process of reasoning every portion of a residual of solu-
tion G, due to the departure of the actual distribution of compensation with
respect to depth from the assumed distribution, or due to the error in the
assumed mean depth of compensation, or to regional variation from a fixed
depth of compensation, or due to errors of observation in the astronomic
determinations and the triangulation which affect the observed deflection of
the vertical, or due to errors of computation, is credited to incompleteness of
compensation,?

The objection to the paragraph quoted is that it apparently is
taken for granted that the error in the assumed mean depth of
t Solution G, the most probable solution according to the first report, was made

assuming a depth of compensation of 70 miles.
2 Quoted from p. 164 of 1909 report.

612 HARMON LEWIS

compensation increased the size of the residuals. Is it not very
probable that the introduction of an error in depth actually dimin- -
ished the residuals? The most probable depth was calculated on
the assumption of completeness. If the assumption of complete-
ness was wrong, the depth of compensation which would appear
most probable would not be the true depth of compensation but a
depth which would counteract the effect of the wrong assump-
tion in regard to completeness. In other words the error in
the assumed mean depth of compensation would be such as to
decrease the residuals. Therefore the residuals which would have
been obtained had the correct depth been used would be larger than
the residuals actually obtained. The degree of incompleteness as
measured by Hayford’s method would, therefore, be larger.

Tf the depth of compensation were known independently, then
Hayford’s method of finding the completeness would be legitimate.
To go back to the example cited before, suppose that it is known
independently that the depth of compensation is 25 miles and
suppose that the residual obtained on this basis and assuming
complete compensation is 15’’: this value would be the part of
the topographic deflection which had not been made up for by
compensation and therefore the ratio of 15 to 35.79 would be an
approximate measure of the incompleteness of compensation.

The above argument will be made clear by a brief summary. The
depth and degree of completeness of compensation are unknowns
to be determined. It is claimed that these two unknowns can
not be determined by Hayford’s method of assuming complete
compensation, calculating the most probable depth, and using
the residuals to tell the degree of incompleteness, because this
method would only be legitimate for the one case when compensa-
tion is actually complete. If compensation were not complete,
then Hayford’s calculated depth would be wrong and would
furthermore be in error in sucha direction as toat least partially make
up for the wrong assumption regarding degree of completeness.
The resulting residuals would therefore not furnish a maximum
measure of the degree of incompleteness; but the compensation
would appear to be more nearly complete than would be the fact.

We are forced to conclude that, from the geodetic evidence

THE THEORY OF ISOSTASY 613

alone, neither the depth nor the degree of completeness of isostatic
compensation can as yet be considered settled.

Criticism of C-solution.—The criticism might be made of the
C-solution that the assumption of complete compensation at depth
zero under oceans obviously does not correspond to the facts and
that, by trying several depths, a combination might be found which
would appear to be, so far as the information available could test
it, as close to the actual conditions as any other hypothesis. From
the wide departure of the C-solution it seems, however, rather
improbable that such a depth could be found.

FURTHER CONSIDERATIONS

Possibilities of an incomplete compensation.—Since Hayford
only considered the case of complete compensation, it is desirable
to see whether or not an incomplete compensation would meet the
geodetic requirements as well as a complete compensation. Any
test of incomplete compensation based on Hayford’s residuals is
apt to be misleading since these residuals may involve two errors
that tend to counterbalance each other. By a study of the reduc-
tion factor, however, we may be able to tell whether or not an
incomplete compensation would be as probable from the geodetic
point of view as complete compensation.

According to the definition given in this paper the fees of
completeness of compensation is

abh—(Wa—Ws)
aoh ; (x)

If there is isostatic compensation, there will be a compensating
density difference between the material in column A and the
material in column B.?_ If at any given depth the density of column
A be 64 and of column B, 6,, then the compensating density differ-
ence at that depth will be 6,=6,—6, which is of course negative
when A is a land segment. It follows that 63=6,—6,. Now

tIt should be noted that so far as the nature of compensation is questionable,
Hayford’s values for the size and figure of the earth are also open to question.

2 See definition of M, p. 607-8.

614 HARMON LEWIS

(uth)
Wan a is the weight* which the column A would have if its

density were the same as in column B and is therefore equal to the
weight of B plus the weight which the material in A above sea
level would have if there were no isostatic compensation. Thus

(ath)
Wa- of =Wp+abh

or
(Ax +h)
a-Wa mobs | ba (2)
Substituting (2) in (1),
| (Ax +h)
aoh— ato fa
M= aoh

(Ax+h)
dhM = - {a0 (3)

The case of a uniformly distributed compensation will be con-
sidered. In this case, 6, being a constant, (3) reduces to
dhM = —8,(s+h) (4)

As stated before Hayford only considers the case where M=t.
He further makes the approximation of neglecting / in comparison
with /;. This approximation which is permissible for depths of
compensation considered by Hayford but which would not be
allowable for shallow depths is discussed later. The relation cor-
responding to (4) which Hayford uses is dh=—6,h,. If however
the unknown quantity, M, is retained, the corresponding reduc-
tion factor which we will call Fy is as follows:
: P+V ()P+he
jy ae ie ta genes (s)

log =

t As 6; may vary with the depth it is necessary to sum up the product of 6, and
the small elements of depth rather than use the product, 6:(/1++h).

THE THEORY OF ISOSTASY 615

Adding and substracting M, we have
Fyu=1—M(1—-F) (6)
where F, the reduction factor obtained by Hayford, is

D poy ()?-+h,?
pane h+V Real ie p

log i

(7)

Comparing F with Fy we see that, when O< M<1, Fy will be
greater than F for the same ring’ and #,._ Also for any given ring
F is larger, the larger the depth of compensation,’ /,. It follows,
therefore, that Fy for M<1 calculated on any given h, will be
greater for all rings than the corresponding factor, Ff, calculated
on a smaller h,, for

i ee nae

Now assuming M@=1 Hayford has already shown that the set of
factors obtained when /,=76 miles gives a closer result than the
set of larger factors obtained when h,>76 miles. It seems probable.
therefore that, if a solution were to be attempted assuming O< M
<1, nothing would be gained in taking a depth of compensation
larger than the most probable depth assuming M=1. The writer
would not care to make the preceding statement as a positive
fact without an inspection of the data for the calculation of the
topographic deflections. For it seems possible, although not
probable, that a combination of <1 and h,>76 might yield as
close a result as M=1 and /#,=76 on account of the fact that,

tIn calculating the topographic deflection the area around any station is divided
into concentric rings whose outer radii are 7? and inner radii, 7x.

2See table, p. 70 of 1909 report.

616 HARMON LEWIS

though the reduction factor becomes larger, the relative increase
in the various rings is not the same as the increase when /, is made
larger than 76 but M is kept equal to 1.

On the other hand, when o<M<i1 and h,<76, the resulting
factor, for any given ring, compared to F for 4;= 76, tends to become
larger on account of taking <1, but tends to become smaller on
account of taking 4,<76. If hk, be taken sufficiently small, the
factor, Fm for M<1, and h,<76, becomes smaller for certain rings
and, larger for other rings than F for h,=76. It therefore seems
quite probable that a combination of M<z1 and h,<76 should
prove to be as close an approximation to the facts as M=1 and h,=
76.

Similarly, if the case where M@>1 were to be considered, the
best depth of compensation would probably turn out to be greater
than 76 miles.

By equation (6) above, it is an easy matter to calculate the factor
Fy for any value of , which is equal to the radius of any ring. In
order to obtain a typical example, the factors were calculated assum-
ing M=.5 and h,=19.29 kilometers (11.987 miles) and are given
below together with the factors for Hayford’s most probable solu-
tion in which it was assumed that M=1 and h,=113.7 kilometers
(70.67 miles).7

It will be noted that, for outer rings, the factor, Py, is approxi-
mately .5 while F is nearly zero. From the examples of calcula-
tions of ‘‘topographic deflections” given by Hayford it would
seem that the outer rings, especially the oceanic compartments,
have a considerable effect on the topographic deflection. It
might seem, therefore, that M=.5, 4:=19.29 kilometers would
not give as close a result as M=1, #;=113.7 kilometers; but
without some sort of test this question would remain a matter of
conjecture. Furthermore the additional hypothesis might be
introduced that the compensation under ocean areas is complete
or even that ocean areas are over-compensated. Then when we
remember that the assumption regarding either M or h, or both may

« The value of the depth of compensation given in the first report as most probable
is 70 miles. In the second report 76 miles is given, but the reduction factors for this
depth are not published.

be varied, there seems to be nothing to show that a combination of
a decided under-compensation and shallow depth under land areas
with a practically complete compensation under ocean areas
would not prove, so far as present information is able to test it,
as close an approximation to the actual conditions as a combination
of complete compensation with a depth of 76 miles under both
And it is not improbable that several combinations
involving a decidedly incomplete compensation under land areas
could be found which would appear equally as close to the truth

land and sea.

THE THEORY OF ISOSTASY

as M=1 and h,=76 miles.

In the case of M>1, h,>76 miles it is probably also true that
the compensation under ocean areas would have to be taken com-

plete.

In the foregoing discussion the distribution of compensation

eras kil.

epee avakale

-996
-994
-9QI
.988
.982
-975
.965
.950
.930
.QOO
. 860
. 809
747
679
.617
.570
-539
.520
.510
505
502
. 501
. 500
. 500
. 500
. 500
. 500
. 500
. 500

-997
.996
-995
992
988
.983
-976
-965
-O51
-930
evo\e)
.859
. 801
afl
.618
-493
358
234
- 139
:077
.040
.020
.OTO
.005
.003
OO
.OOI

618 HARMON LEWIS

was assumed uniform. The argument that, if M <1, h, is probably
less than the most probable depth assuming M=1 would hold
for the Chamberlin compensation or for a compensation uniformly
varying from a maximum at the surface to zero at the depth of
compensation. For the reduction factors in the subsidiary investi-
gations are linear functions of the reduction factor for uniform
distribution.

Changes in formulae required by shallow depth of compensation.—-
Under this head the approximation mentioned above in connection
with equation (4) will be considered.

dhM = —8,(h, +h) (4)

6, is such a quantity that (W4—a0, [h,+h]) =[Wal,,_, is the
weight which column A would have if there were no isostatic com-
pensation. Therefore

Wa=(Waly— tad +h)

Thus the deflection due to W4 may be obtained by adding to the
deflection which would be produced if there were no isostatic com-
pensation the deflection which would be produced by a6,(h,+h).
Therefore the deflection at any station assuming isostatic compen-
sation is equal to the topographic deflection (D) plus the deflection
(D.) due to the defect or excess of density from the surface down to
the depth of compensation. If H be the height of the observing
station above sea level, then the deflection due to the defect of
density in a compartment whose surface is # miles above sea level
is (neglecting the curvature of the earth),

6: ° °
1D): 44 (sin at'—sin ay) / (H+h:)log

rP+YV (7)?+(H4+h:)?
nV r+ (Ath)?

petal OTE
n+V re+(h—H)?

+ (h—H)log (8)

In calculating the topographic deflection Hayford neglects H
except when it is necessary to make a slope correction. However,
H is introduced in equation (8) in order to make it exact. Whether
it would be legitimate to neglect this factor or not can best be told

«See A. R. Clarke, Geodesy, 1880, p. 295, and Figure of the Earth and Isostasy,
1909, p. 20, for the derivation of equation (8).

THE THEORY OF ITSOSTASY 619

from the resulting expression for the reduction factor. Taking
the value of D, given in (8) the reduction factor is

D-+-D, t \8(H+h), 2P+V (7)+(A+h)?
SS Ss lo

Fu ee
D B dh : fia V ean h;)2

(9)

Ey manvs a
BE? eb re (iB
From (4)
5: Mh
Se oo)

Substituting (ro) in (9)

og PAV (P+ (H+hn)?
ie M(H+h) > ntV re+(A+h,)?
Mie
hth pa
log ~

eV OOO
Mis aa Ce

aa 2 (11)

This reduces to Hayford’s factor if M be put equal to 1 and H
and / be put equal to zero. These are the three approximations on
which Hayford’s factor is obtained. If h, is large, it is legitimate
to neglect H and h; but if 4, were to be taken as 12 miles and H
would certainly have to be considered. This fact would increase
the length of the computations since for a complete solution of the
problem a different factor would be necessary for each compartment
whereas, before, the same factor was used for an entirering. Doubt-
less, however, devices could be employed which would facilitate
the calculations.

The necessity of having to use the reduction factor given in
(11) serves to make the depth and degree of completeness of com-
pensation more open to question than ever.

SUMMARY

On the basis of Hayford’s work it may be considered settled
that there is some sort of isostatic compensation, but so far as
Hayford’s investigation has yet gone there are many possibilities

620 HARMON LEWIS

as to the nature of this compensation. None of the possible distri-
butions of compensation have been eliminated by Hayford’s
geodetic work; in fact, so far as the geodetic work is concerned,
Hayford has shown that four different distributions of compensa-
tion are equally probable.

The present possibilities for isostatic compensation may be
grouped with considerable certainty under three heads: first, there
is the possibility of complete compensation at a depth in the
neighborhood of 60 to 150 miles depending on the distribution of
compensation; second, there is the possibility of an over-compensa-
tion at a greater depth for land areas with probably complete com-
pensation for ocean areas; and third, there is the possibility of
under-compensation at a shallow depth for land areas with com-
plete or over-compensation for ocean areas.

SECTION III. THE THEORY OF ISOSTASY
INTRODUCTORY

In any theory of earth movements it is recognized that the
earth is a failing structure in the sense that it has been and is
being permanently deformed under the ultimately controlling
force of gravity. It is not therefore the essential idea of the theory
of isostasy that the earth as a whole is a failing structure; but the
characteristic of the theory is the type of deformation which it
postulates. This may not be the critical point of isostasy as it
was originally conceived, or as conceived today by everyone; but
it is the point which has been elaborated by the supporters of the
theory and which is of first importance to the geologist; and it
will therefore serve as a basis of criticism in this paper.

Type of deformation postulated in the theory of isostasy.—The
controlling movements of the earth’s crust are vertical movements
of the various segments in response to changes of weight produced
by erosion and deposition.

These vertical movements are brought about by flowage beneath
the surface from areas of deposition to areas of erosion or, in general,
from areas of excessive weight to areas deficient in weight.

This flowage beneath the surface is comparable in speed to the
process of erosion and is started under stress-differences so small

THE THEORY OF ISOSTASY 621

as to require that all segments of the earth of given area are essen-
tially equal in weight.

This flowage may be accompanied by folding in the border
zones of the segments.

Deformation of this kind is not restricted to the major segments,
the continents and oceans, but is the type of movement which
takes place between the smaller units of the continents.

Lines of criticism of isostasy.—In criticizing the theory of isostasy
two main lines of argument will be followed. First, the type of
deformation postulated by isostasy can not account for certain
facts. Second, Hayford’s geodetic results can be accounted for
without supposing the type of deformation postulated by isostasy.

FACTS NOT ACCOUNTED FOR BY THE TYPE OF DEFORMATION POSTU-
LATED IN THE THEORY OF ISOSTASY

The degree to which isostasy must be discarded depends on the
importance of the phenomena which it will not explain.

The theory of isostasy as conceived in this paper does not adequately
account for the folding of rocks of the earth’s crust.—Folding is evi-
dence of lateral forces of enormous magnitude. On the other hand
the controlling movements of isostasy are assumed to be vertical
movements. However, it has been suggested by Hayford that
folding would be caused by the undertow from an area of deposition
to an area of erosion:

Horizontal compressive stresses in the material near the surface above the
undertow are necessarily caused by the undertow. For the undertow neces-
sarily tends to carry the surface along with it and so pushes this surface material
against that in the region of erosion, see Fig. 2. These stresses tend to produce
a crumpling, crushing and bending of the surface strata accompanied by
increase of elevation of the surface. The increase of elevation of the surface
so produced will tend to be greatest in the neutral region or near the edge of
the region of erosion, not under the region of rapid erosion nor under the region
of rapid deposition.*

This undertow must exist chiefly below the depth of compensa-
tion. If the earth were a perfect fluid the materials of different
densities would, if not diffusible, arrange themselves in concentric
shells with the heavier material toward the center. There is always

t Science, February 10, IQII, p. 205.

622 HARMON LEWIS

a tendency for the earth to take this arrangement in the sense that
the stress-differences are on an average tending in this direction.
It would seem, therefore, as a general proposition, that where the
material of the earth is weak, the tendency would be more toward
equalization of densities laterally than toward lateral differentiation
of densities such as implied by isostatic compensation. Even
though the stress-differences due to lateral variations in density
were not sufficient to deform the rock so as to equalize the densities,
a flowage from beneath an area of deposition to an area of erosion
would certainly tend to produce a distribution of density within
the zone of flowage itself which would have no relation to topog-
raphy. It appears, therefore, that there could be very little
isostatic compensation in a zone where yielding occurs as readily
as postulated by isostasy.

Now, according to the theory of isostasy, compensation would
be essentially complete, and if compensation is complete the depth
of compensation as determined by Hayford’s geodetic work would
be as great as 60 miles. Hence, the undertow postulated by
isostasy would exist chiefly below 60 miles. It is decidedly ques-
tionable that an undertow even much nearer to the surface than
60 miles would cause the observed folding in the upper few miles
of the crust.

The theory of isostasy cannot account for the general uplift of sedi-
ments without folding.—If the isostatic compensation is complete
any deposition of material should cause a sinking of the under-
lying segment. Isostasy could not therefore account for the fact
that horizontal sedimentary rocks are found far above sea level
unless a lowering of the sea level were supposed; but this possi-
bility can generally be dismissed because the relative change in
sea level is not registered in all parts of the world.*

1In discussing isostatic adjustments (see Science, February 10, 1911) Hayford
. suggests that some uplifts are due to expansion and contraction caused by heating and
cooling of sedimentation and erosion. These deformations, however, are not a distinc-
tive assumption of the theory of isostasy at least as the theory is conceived in this
paper; but were suggested to account for certain geological phenomena which the
theory of isostasy could not explain.

At any rate, expansion due to heating effect of sediments is entirely inadequate
to account for known uplifts. In making his estimate that the vertical expansion is

THE THEORY OF ISOSTASY 623

The theory of tsostasy does not explain the apparently heterogene-
ous relation of uplift and subsidence to erosion and deposition.—Since
isostasy postulates an adjustment or flowage which is comparable
in speed to the process of erosion, a high area which is subject to
erosion should be further uplifted as erosion progresses and should
not be reduced to sea level until its deficient density is equalized
by erosion of the lighter material at the surface and restoration of
heavier material below. With a depth of compensation of 76
miles, the theory of isostasy would require greater continuous
uplifts than are known to exist. Asa matter of fact, some areas
have been uplifted as erosion progressed and others have remained
stationary. In some cases erosion to a peneplain has been fol-
lowed by subsidence and in other cases by uplift.

ALTERNATE HYPOTHESES TO ACCOUNT FOR HAYFORD’S GEODETIC
RESULTS

Erosion and deposition are assumed to be the principal cause
of disturbance of the equilibrium condition of isostasy. Since
deposition does not in general extend beyond the boundaries of the
continental shelves, the cause and effect of the type of deformation
postulated by isostasy would be confined to the continents proper.
So far, then as distributions of density are to be made a proof of
the theory of isostasy, the critical test is not in the density relation
of the continental masses as a whole compared to the ocean basins,
but in the completeness of compensation of the topographic features
of the continents. Now it has been shown in the preceding section
of this paper that, though there is very likely a complete compensa-
tion of the ocean defects of mass, yet it is a distinct possibility so

one foot for every 33 feet of deposition Hayford neglects the fact that the irregularities
in the isothermal surfaces near the surface of the earth flatten out with depth. How-
ever, taking Hayford’s estimate and assuming that an area of deposition was covered
by very shallow water and that the expansion due to heating took place all at one
time, the maximum uplift above sea level could not be more than one-thirty-third
of the thickness of the sediments deposited. Subsequent erosion would tend to
reduce this elevation and any further elevation caused by relief from eroded material
would certainly not more than equal the eroded layer. Hence, wherever the present
elevation above sea level is more than one-thirty-third the thickness of the last con-
formable sedimentary series, some other factor than expansion due to heating effect of
sedimentation must be sought to account for the uplift.

624 HARMON LEWIS

far as the geodetic evidence is concerned that the compensation
of the topographic features of the continent is decidedly incomplete.
The theory of isostasy can not therefore be considered as established
by the geodetic work of Hayford. Furthermore, the probability
that isostasy exists is lessened by the fact that an incomplete com-
pensation can be very plausibly explained without involving the
conceptions of isostasy.

The tendency of lateral compression to produce isostatic compensa-*
tion.—In the folding and overthrust faulting of rocks there is abun-
dant evidence of lateral compression. It has already been shown
that this folding is probably not caused by an undertow such as
isostasy supposes to be set in motion by erosion and deposition.
The compression indicated by folding may be due to shrinkage
of the earth; it may be due to squeezing of the continental segments
by the oceanic segments; or it may be due to other causes; but
whatever the cause may be, it is certain that it has produced great
uplifts. Suppose that the continent is composed of portions of differ-
ent densities, but that the stress-differences set up by these differ-
ences in density are not sufficient to cause a deformation of the
material and a consequent uplift of the lighter masses. If this were
the case, it would seem reasonable to believe that there would be a
tendency for the effects of lateral compression to localize in the
lighter segments since there is always a tendency for lighter seg-
ments to move up even though the stress-differences tending in this
direction are not sufficient to produce an actual movement. Other
things being equal, folding would probably tend to localize in sedi-
mentary rocks since the parallel bedding planes allow slipping to
take place readily. Here again there might be a tendency toward
isostatic compensation since sedimentary rocks on an average
are lighter than igneous rocks. There are undoubtedly other
factors which determine the place of folding, but it is entirely
possible that uplifts by folding are incompletely compensated.

A compensation of areas which have been uplifted without
folding may be accounted for in a similar way. It is possible that
lateral forces similar in magnitude to those forces which produce
folding at the surface, but localized at greater depth should cause
a deformation which is registered at the surface simply as a general

THE THEORY OF ISOSTASY 625

uplift. In this case also the deformation would tend to localize
where the resistance to uplift were least, in other words, in the
lighter segments.

The type of deformation suggested here is perfectly distinct
from that postulated by isostasy. The theory of isostasy supposes
that light areas are high because the strength of the material below
is not sufficient to support segments different in weight. The
possibility suggested in the preceding paragraphs is that high
areas are light because the great deforming forces of the earth
follow the path of least resistance.

The automatic compensation of uplifts and subsidences due to
expansion and contraction.—lIt is possible that some uplifts and sub-
sidences are due to expansion and contraction of the underlying
material. Such deformations are not a distinctive assumption
of the theory of isostasy. Changes of volume may be due to
changes of temperature or pressure which in turn may be due to
a variety of causes. Any changes of elevation caused by expansion
or contraction will be automatically compensated since the weight
does not change. This would be another factor tending to produce
compensation which does not involve the type of deformation
postulated in isostasy.

SECTION IV. SUMMARY OF CONCLUSIONS

Isostasy is a theory of earth movements based on the assump-
tion that the lighter portions of the earth are elevated in propor-
tion to their defect of density because the earth is not strong
enough to support segments of different weights. The principal
support for the theory is the geodetic work of Hayford from which
it was concluded that the excesses of mass at the surface are com-
pletely compensated for by defects of density below, said defects
of density extending to a depth of something like 60 to 150 miles.

It is believed that Hayford made an error in determining the
degree of completeness of compensation which invalidates his
conclusions, for he assumed complete compensation in calculating
the depth and then used this depth to calculate the degree of com-
pleteness. Hence, instead of the single possibility of a practically
complete compensation, there are, so far as has been shown from

626 HARMON LEWIS

the geodetic evidence, three groups of possibilities for isostatic
compensation: first, the possibility of complete compensation at a
depth in the neighborhood of 60 to 150 miles depending on the
distribution of compensation; second, the possibility of an over-
compensation at a greater depth for land areas with probably
complete compensation for ocean areas; and third, the possibility
of under-compensation at a shallower depth for land areas with
complete or over-compensation for ocean areas.

Hayford’s geodetic results do not, therefore, constitute a proof
of the theory of isostasy.

An incomplete compensation of the topographic features of the
continents can be plausibly explained without supposing the type
of deformation postulated by isostasy.

There are many important phenomena which the theory of
isostasy will not explain.

SPECULATIONS REGARDING THE GENESIS OF THE
DIAMOND

ORVILLE A. DERBY
Rio de Janeiro

The recent admirable summary by Dr. Percy A. Wagner’ of
what is now definitely known regarding the geological conditions
in which the diamond occurs in South Africa suggests certain specu-
lative points of view, which, if found worthy of attention, may in
turn suggest desirable lines of investigation in the field and the labo-
ratory. These inquiries may perchance throw light on the intricate,
fascinating question of the genesis of the diamond; or, even in
a broader way, on the réle of carbon in eruptive rocks, whether in
the form of diamond or graphite, or as gas locked up in carbonates
or certain silicates.

To the student of the occurrence of the diamond in countries
other than South Africa, one of the most significant facts established
by the prospecting of the African miners is that, aside from its
well-known occurrence in pipes, the diamond-bearing eruptive
material, kimberlite, occurs also in dikes, and that these usually
have considerable longitudinal extension but only small width,
except where expanded into pipes, and even these are frequently
insignificant in relative dimensions. This slight prominence of the
diamond-bearing bodies, coupled with the extreme susceptibility
of the material to alterations which render its identification a matter
of great difficulty, suggests at once that the failure to detect such
dikes and pipes in districts in which the diamond is found only in
sedimentary deposits, modern or ancient, is not a conclusive argu-
ment against their existence, nor is it clear evidence that the original
matrix was notably different from the South African kimberlite.
In countries like India and Brazil, in which the diamonds of the
modern alluvial deposits have been definitely traced back to con-
glomerates of considerable geological age, the presence or absence
of kimberlite dikes should be tested by prospecting operations,

* Die diamantfiihrenden Gesteine Siidafrikas, Berlin, 1909. .

627

628 ORVILLE A. DERBY

not so much, perhaps, in the areas occupied by the conglomerates
themselves as in the neighboring ones occupied by formations
known to have been in existence when the conglomerates were laid
down, and which have escaped being covered up by them or by later
strata. Until such prospecting is done on a sufficiently large and
efficient scale the opinion, which a few years ago seemed justified,
that a mode of occurrence essentially different from the African
must be postulated for these countries, should be held in suspense.

The material filling the African pipes shows very pronounced
fragmenting and apparently explosive action, which has shattered,
and to some extent scattered, the eruptive rock characteristic of
both the pipes and the dikes and has mixed it with a very consider-
able amount of various other rocks, either brought up with it from
lower horizons or detached from the surrounding rock masses. Dis-
cussion is still going on as to whether the diamonds contained in
these agglomeritic pipe-fillings are to be assigned to the eruptive
rock proper or to some of the foreign rocks included in it, but the
weight of evidence seems to be in favor of the first hypothesis. A
very interesting view that was held for many years assigned the
formation of the diamond to some kind of reaction zm situ, between
the two classes of rock that occur in the pipes, the necessary carbon
being supplied by the carbonaceous rocks through which, in some
places, the pipes cut. Subsequent developments have completely
disproved this hypothesis, but the essential part of it—the formation
of the diamond im situ—is still worthy of consideration 7f another
source of carbon can plausibly be brought into the question.

So general is the association of the diamond with a fragmental
state of the eruptive rock that enters into the composition of the
pipes that the question naturally arises whether or not the diamond
also occurs in such masses of this rock as have not been subjected to
the fragmenting action. From the statements at hand it is clear
that there is usually considerable difficulty in distinguishing between
the massive and the fragmental forms of kimberlite. Apparently
the distinction has only been made in a perfectly conclusive manner
by the use of the microscope. The masses that can be thus exam-
ined are so small that such negative evidence as they may give has
in itself little value. Specimens of diamonds inclosed in fragmental

THE GENESIS OF THE DIAMOND 629

material are quite common, but thus far those found in which the
rock is clearly non-fragmental seem to be exclusively of the type
of the so-called “eclogite nodules,”’ which are regarded by some as
segregations in the kimberlite magma and by others as transported
fragments of a pre-existing rock. In either case the experimental
crushing, reported by Mr. Gardner Williams,’ of 20 tons of these
nodules from the Kimberley mine without finding a single diamond,
tells strongly against any general hypothesis of genesis based on
the sporadic occurrence of these nodules.

In the statements at hand relative to the occurrence of diamonds
in the parts of dikes that are not expanded into pipes, the impression
is given that the rock is non-fragmental; but the evidence on this
point is not as clear as one could wish. As the case stands at present,
and until unequivocal evidence to the contrary is presented, there
is a reasonable presumption that a positive, perchance a genetic,
relation exists between the diamond and the fragmental condition
of the rock in which it occurs. This in turn may mean that the
origin of the diamond can perhaps be assigned to reactions between
the original rock, or rocks, of the filling and other elements whose
introduction was made possible by the fragmenting of the mass,
and which accompanied, or followed, the explosive action, if, per-
chance, they did not constitute the actual agency that produced it.

According to ideas generally received among geologists, the
explosive action, as such, is but the culmination of previous thermal
processes in the sudden production of gases, principally water
vapor. The thermal processes may be protracted and varied in
action and may occur repeatedly and extend into late phases of the
eruptive period and to stages subsequent to it. One of the most
important effects of the protracted action would be to saturate the
fractured mass of rock with gases and with liquids resulting from
their condensation. Various observers have expressed the opinion
that this saturation under the conditions implied reached the point
of establishing a marked degree of mobility in the mass, converting
it into a veritable rock brew. Be this as it may, such a saturation,
whatever its degree may have been, would establish conditions in
which a certain amount of hydration (serpentinization) of the erup-

t Trans. Am. Inst. Min. Engineers, 1904.

630 ORVILLE A. DERBY

tive rock, composed largely of olivine, would almost inevitably
result.

We thus have in the formative stages of the pipe-fillings (or at
least in early stages of their history) a sufficient agency for the
hydration of their eruptive portions. Such a change has been
observed down to such extraordinary depths that the usual explana-
tion of atmospheric weathering seems utterly incredible.t The
hydration, which to a greater or less degree seems to be character-
istic of all known occurrences of undoubted kimberlite, whether
appearing in pipes or dikes, is accompanied by the formation of a
certain amount of calcite, which involves the introduction, in some
stage of the history of the rock, of carbon in a condition to form the
carbonic acid locked up in the mineral. This introduction may also
be most plausibly assigned to the stage of thermal agitation, of
which the fragmenting and explosive actions were the climax.
The analysis cited in the preceding note, representing the least-
altered kimberlite thus far examined, gives 2.54 per cent of carbonic
acid, corresponding to about 5,000 grams of pure carbon to the
unit of volume (load=o.453 cubic meters) used by the African
miners in measuring their material. This amount of carbon,
if present in the form of diamond, would give about 25,000 carats,
whereas the usual yield of the De Beers load is under 1 carat
(t/5 gram).

There are thus strong a priori reasons for attributing to deep-
seated causes long since extinct a great part of the hydration and
carbonation which the eruptive rock, originally free from water
carbon, has suffered. If such was the case, it becomes important
to distinguish the deep-seated actions from those of the atmosphere,
which, acting from above downward, have long been producing
similar results. These superficial results would be superimposed on
the pre-existing ones, if such existed, down to a certain depth.
No question can be raised regarding the correctness of the view,

t Dr. Wagner gives an analysis of a specimen of kimberlite collected in the deepest
part (2,040 feet from the surface) of the De Beers mine, which had 6.81 per cent of
combined water. ‘This, as he expressly states, represents the best-preserved material
to be found in the Kimberley group of mines, although in the neighboring Kimberley
mine the pipe has been opened up nearly 1,000 feet farther down, or fully 3,000 feet
from the surface. From this it may legitimately be inferred that there is little likeli-
hood of finding unhydrated kimberlite in the known South African diamond mines.

THE GENESIS OF THE DIAMOND 631

very generally received, that atmospheric weathering has trans-
formed the “hard blue” ground into “soft blue,” and this in turn
into “yellow” ground. If, as here suggested, there had been a
previous period in which serpentine and calcite were formed,
evidence for or against it should be found in the transition zone
between the hard and the soft blue ground. So far as can be
gathered from the literature at hand careful search has never been
made for such evidence. This seems thus to be one of the crucial
points in the study of the genesis of the diamond that is yet to be
investigated.

On the assumption that future investigation may establish the
deep-seated origin of the alteration of the diamond matrix, a basis
is found for submitting to discussion the elements of a new hypothe-
sis regarding the genesis of the diamond. A pipe filled with rock
fragments saturated with hot (possibly superheated) gases, and
probably also liquids, would constitute an enormous crucible, in
which reactions not as yet detected in our laboratories might take
place. In this crucible carbon would certainly be present in the
form of carbonic acid and probably in other gaseous forms as well.
Thus the material and some of the physical conditions for unusual
carbon segregation were present, and we are not yet, apparently,
in a position to say that a segregation of a minute portion of the
carbon into a solid form is a chemical impossibility. It seems to be
well established that in certain industrial and experimental processes
carbon does separate in the solid form of graphite from carbonaceous
gases, and Weinschenk has presented strong evidence in favor of
the introduction in a gaseous form of the carbon of the graphite
deposits of Bohemia and Bavaria.

From a geological point of view the réle of carbon in eruptive
rocks and in eruptive phenomena generally is as important as it
is obscure. It thus presents an attractive subject for experimental
researches, such as are contemplated in the program of the Geophysi-
cal Laboratory at Washington, which is so admirably equipped both
in material and personnel for such investigations. The inquiries
in this line thus far reported by various experimenters, while
extremely interesting and important in themselves, are unsatis-
factory, in so far as they postulate conditions that are with diffi-
culty conceivable in nature.

PRELIMINARY NOTES ON SOME IGNEOUS ROCKS OF
JAPAN. IV!

S. KOZU
Imperial Geological Survey of Japan

IV. ON LAVA AND ANORTHITE-CRYSTALS ERUPTED FROM THE
TARUMAI VOLCANO IN 1909

Introduction.—The volcano Tarumai is located at a distance of
about 42 kilometers south of Sapporo, the chief city of Hokkaido.
Though the volcano has long been known as one of the active
volcanoes in the district, it has become the object of special atten-
tion since the outpouring of lava, which took place in April, 1909,
forming a dome of 134 meters in height as measured from the
neighboring ground, and adding 4o meters to the pre-existing
highest peak of the mountain, which is 1,015 meters above the sea-
level, according to Oinoue’s report.

A revival of the exhausted volcanic energy, which had remained
in the solfataric state since the comparatively great explosion of
August 17, 1895, took place at the beginning of the year 1909.
After that several outbursts and shocks were reported from the
region. At last, in the course of about 24 hours, from the evening
of the 17th to that of the 18th of April, lava of about 20,000,000
cubic meters in volume, measured by B. Koto, was poured out of
the explosive crater, and a dome was formed which is shown in the
accompanying photographs (Figs. 1 and 2).

Reports of the event, written in Japanese by D. Sat6 and Y.
Oinoue, have been published by the Imperial Geological Survey of
Japan and the Earthquake Investigation Committee, respectively.
The following brief petrographic description was made by the
writer on the specimens collected by D. Sato.

Megasco pical characters.—The specimens at hand have in general
a glassy and ragged appearance. Those taken from the ejecta are

t Published by permission of the Director of the Imperial Geological Survey of
Japan.

632

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 633

of light-colored pumice. In their inner part the cellular structure
appears well developed, while the outer thin crust is usually
glassy and compact, strongly marked by cracks, which are char-

Fic. 1.—View of the new dome from the east, May 11, 1909 (by T. Kawasaki,
Imp. Geol. Surv. of Japan).

Fic. 2.—View of the new dome from the southwest, May 11, 1909 (by T.
Kawasaki).

acteristic of the so-called bread-crust bombs. This variety con-
tains well-formed anorthite crystals of considerable size, with an
average length of 13 mm. Beside these, there are not a few small

634 SKOZO,

megascopic phenocrysts of feldspar and pyroxene, their sizes vary-
ing from 1mm. to 2mm. The other specimens taken from the
new dome are dark gray, or reddish dark gray, in color and spongy
or ragged in appearance. Generally, they are characterized by
heterogeneity in texture due to their variable crystallinity, and by
flow-structure, which is visible in the lava-mass, as shown in Fig. 3.

Fic. 3.—Lava-block, showing the marked flow-structure

Sometimes dark-gray to light-gray cryptocrystalline masses are
imbedded along the planes of flow in the rock-mass, their shapes
being mostly lenticular.

Microscopical characters —The rock is made up of plagioclase,
hypersthene, augite, olivine, magnetite, apatite, and microliths,
scattered in the abundant glassy groundmass. The prevailing
phenocrysts are of anorthite. Hypersthene comes next, and is
nearly equal to, or is more than, the augite. Subhedral magnetite
is not rare as phenocrysts. Though olivine appears abundantly
associated with the large crystals of anorthite, mostly as peripheral

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 635

inclusions, it is rarely met with in the general mass, and may be
considered as an accessory constituent of the rock.

The matrix exhibits different textures, according to different
conditions under which the lava consolidated. The crustal part
of the ejecta is hypohyaline, while its inner part usually shows
typical cellular structure, the glass base being colorless. The
specimens taken from the dome are more crystalline than those
just described, but there is still abundant residual glass. It is
moderately clouded with magnetite dust and pyroxene microliths.
The megascopically cryptocrystalline part appears holocrystalline
under the microscope and consists essentially of granular pyroxene
and feldspar, scattered microporphyritically with skeletal crystals
of hypersthene.

Feldspar.—The feldspar phenocrysts are of two kinds. One of
them is well-formed anorthite of considerable size, 13 mm. in
average length. Zonal structure is nearly wanting, or is indis-
tinct. These occur in the ejecta and peripheral part of the lava,
or even as isolated crystals, suggesting that their crystallization
was prior to that of other minerals. The other variety is smaller
in size, with an average length of 2 mm., and is commomly sub-
hedral in shape, sometimes with a strongly curved outline invaded
by the glassy groundmass. This variety differs from the first in
possessing zonal structure due to variation in the chemical compo-
sition and to the arrangement of abundant inclusions. In average
composition, the second variety is slightly more sodic than the
first. The most abundant inclusions are light-brown or colorless
glass with air bubbles in many instances. Apatite and magnetite
are also present, commonly in small quantity. In some crystals
pyroxene appears as inclusions, but more commonly the feldspar
is abundantly inclosed in the hypersthene and augite phenocrysts
and shows a distinct automorphic relation toward the pyroxene.
’ The larger crystals will be more fully described in the second part
of this article.

Pyroxene.—The hypersthene is easily distinguishable from the
augite by marked pleochroism, low double refraction, parallel
extinction, and crystal habit. It occurs in crystals of two periods
of crystallization. The largest phenocrysts are 2.5 mm. in length

636 | S. KOZU

along the axis c. Pleochroism is distinct; a=reddish brown, 8=
greenish yellow, y=yellowish green. It is optically negative, the
optic plane being parallel to the orthopinacoid. There are abun-
dant inclusions of plagioclase, magnetite, glass, and a few crystals
of apatite; of these the plagioclase is large and conspicuous. The
smaller hypersthene is rather euhedral in shape and is sometimes
marked with transverse cracks perpendicular to the axis c.

Augite crystals are anhedral to subhedral, and also have abun-
dant inclusions, just as the orthorhombic pyroxene. Parallel
growth with the hypersthene is common, the hypersthene always
being inclosed by augite. Twinning parallel to the orthopinacoidal
face commonly occurs, and that parallel to (zor) is rare.

Olivine crystals, as already stated, occur in association with the
large crystals of anorthite and have well-defined form, elongated
along the vertical axis with a length of about 2mm. The pre-
dominating faces, easily identified by the naked eye, are m(z10),
k(o21), and b(o10). They are usually coated by a dark-reddish
colored, thin crust. They frequently occur in groups of several
individuals associated with a smaller quantity of magnetite grains.
Notwithstanding the noticeable fact that olivine is nearly absent,
or very scarce, in the general mass of the rock, it appears abundantly
as peripheral inclusions of the large anorthite.

Magnetite occurs frequently as phenocrysts in association with
those of pyroxene, and varies in size from 0.1 mm. to 0.3 mm., in
striking contrast with the same mineral in the groundmass, which
appears as dusty grains.

A patite usually occurs as needle-shaped inclusions, but in a few
instances larger crystals with a violet color, finely striated parallel
to the vertical axis, appear in the groundmass.

Chemical characters—The analysis of the rock made by N.
Yoshioka in the chemical laboratory of the Imperial Geological
Survey of Japan is as follows:

SIO ay ci he ee See Cea Siete cer een eats eae re ee 60.93
ATS O)gy ato! 2p le neM Uae tlh amet Forte ne eee g 16.46
| Ice © Rare ean Seu eT Cee cuntR Ie eR ad ory BOR 6 3.35
1 Sis, @ WaPRRen rer nee ea Rese Stee dius, irate ie ceid iG SY 5-94

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 637

(CEN) Oa ooh OSM Na aR A oI oR gr 7.84
TNFa © Peay testa yt «Ate nas coe aseeel ant oe 1.44
IK AO) 8 orale lec a Ree oR RRR RP Omi gma nee 0.79
SEO ere eek erty SRE CRG usta i ee gee a n.d
MIN O ere at. os he hE ih Sins, Seana, nae 0.42
Jee Oar Seat GA EE 0.13
IMO) 8 Ga weet aa Oa Mend SE eae 0.55

100.78

25 eo
Orchoclasepiescqencs cet eas Aches, 5 kia Pace ets: elo)
JNM BYNES cota oi Sa Ree a ee 72a
PAMOREMIL CMe erie cn tee aun evn in See Ss 36.1
ID OVO RIGNS S ce Mara tre Sa hee ance een oe aa 2a
sy ELStMEIM Crys sky aac uN Weak eee Le. sees 13.6
IMIAOMELILE econ nein ho ge Waleh aan ak 4.9
Wlineniterewew aa ute ea Naame. Meret» 0.8

99.7
The ratios are:
Sal
SSR eT a EEE tara 3.66
Fem
Q
SNM RA ews Gatco, enter Deh auras cuenta 0.47
F
K,0’+Na.0’
At RRC IE ev cane re ee 0.25
CaO’
K,0’
BM cars oa cent eran MARA ROIS Spc, ve cet 0.39
Na.0’

By the Quantitative System the rock would be classified under
the name bandose.

In this classification, it may be noted that the rock is charac-
terized by a high percentage of lime, which appears mostly as
modal anorthite, and by the comparatively high silica content.

Generally speaking, the mineralogical and chemical characters
of the latest lava of Tarumai volcano seem to be representative of

638 S. KOZU

those of the modern pyroxene-andesites, which are widely spread
over the Japanese Islands, judging from a cursory glance over
the volcanic rocks of Japan. For this reason the name bandose
appears to be particularly appropriate.

ANORTHITE-CRYSTALS IN THE LAVA OF I909

The occurrence of the larger crystals of anorthite is noteworthy.
The crystals form large phenocrysts in the lava, and have been

Fic. 4.—Cavity with anorthite crystal. Natural size

ejected separately also as the so-called ‘‘anorthite bombs,” and are
scattered abundantly around the crater; as.is the case with the
anorthite on Miyake-jima,’ one of the Seven Izu Islands, Zao-san,
a volcano in the province of Rikuzen, and Iwate-san, a volcano in
the province of Rikuchu; the oligoclase-andesine? on Naka-i6-jima,
one of the Sulphur Islands, may be cited as the parallel examples.

t Kikuchi, ‘‘On Anorthite from Miyake-jima,”’ Journal of the College of Science,
Imp. Univ. Japan, I, Part I, p. 31.

2 Wakimizu, ‘‘The Ephemeral Volcanic Island in the Idjima Group (Sulphur
Islands) ,”’ Publications of the Earthquake Investigation Committee, 1908, No. 22 C,
Tokyo.

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 639

A black, thin coating of lava, which crusts the Miyake-jima
anorthite and the Naka-id-jima oligoclase-andesine, is not seen
on the mineral from Tarumai. The crystals, however, have
attached to them a small quantity of light-colored pumice. It is
evident that the matrix of brittle pumice separated easily from the
crystals and that the semi-solidified lava was not so viscous as in
the case of the lava of Miyake-jima and of Naka-id-jima. Also,
in some specimens the crystal is in a cavity having well-defined

Fic. 5.—Well-defined cavity from which the anorthite crystal has been lost.
Natural size.

walls corresponding to the faces of the crystal, with a space about
4mm. in width between the crystal and the lava. The crystal is
attached to the walls by slender, needle-like filaments of glass, as
shown in the accompanying photographs (Figs. 4 and 5). There
may be several explanations of the formation of these cavities, but
the writer believes they were formed chiefly by the differential
movements of the crystal and matrix when the blocks of lava were
ejected in a semi-solidified state.

The common sizes of the crystals are io mm. to 15 mm. in the

640 SmaKOZU:

longest diameter, though the largest is 20mm. or longer. Their
surfaces are not vitreous, or smooth owing to the presence of
pumiceous matrix and inclusions of olivine crystals with a few
magnetite grains. The olivine is in well-defined forms, as already
described.

The roughness of the crystal faces and the twin striation upon
them made the use of the reflection-goniometer very difficult.
Even the cleavage piece used for the measurement of the facial
angle (oor) : (o10) did not give a satisfactory result, as the reflec-
tion on (o10) was disturbed by the pericline twin striations. The
angle measured lies between 85° 48’ and 85° 52’. Other approxi-
mate facial angles measured by the contact-goniometer are as
follows:

AGE Co} Ss oh do) en ea ene arg Ear le Heb o> 50a 130!
F(20T) SP (OOT)i eat tal Wyte ee ee hn eee ee 81° 10’
v.20) Mi(oro) gcse ake ee eee Poe go° 50’
ViC2On PLO) ihe weer oe ME Ee se na tics i Asc. 20)
Toh eral ed Covey 8 ha unby MUN A alam ne a Ale tLe 42°

M(O2E) ROOT) yee te ewe ael erent Lonmee 46° 40

From the above angles and the relation of the crystallographic
zones the crystal-faces which were identified have been determined
as follows:

P(oor), M(oro), T(1To), /(110), é(201), y(20T), e(021),
n(o21), m(11), o(11), p(1tT), and v(241).

The faces P, M, y, T, /, 0, p, and ” are always observed, of which
P. M, and y are the predominating faces. The face e is very rare,
and ¢, f, v, and m are only found in the tabular crystal parallel to
P(oor).

Some distinguishable crystal habits are formed by the pre-
dominance of different crystal-faces, as given below:

First type: Prismatic, elongated along the axis a, with the
faces P, M, and y predominating, as seen in Fig. 6.

Second type: Tabular, parallel to M, its elongation being along
the axis c, as seen in Fig. 7.

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 641

Third type: Tabular, parallel to P. This type might be sub-
divided into two varieties, with gradations between them:
a) The elongation is rather along the axis a than along the
axis 5, as seen in Fig. 8.
b) The elongation is along the axis 6, with specially well-
developed y, as in Fig. 9, finally becoming thick tabular
parallel to y.

Fic. 10 EiGssnr

Fourth type: Cubic, or equant, with comparatively well-
developed face . This type might also be subdivided into two
varieties, showing gradations into each other or to the first type:

642 S. KOZU

a) With slight elongation along the axis c, as seen in Fig. ro.

b) With slight elongation along the axis a, as seen in Fig. rr.

The prevailing habits are the first and third types; the second
and the 6 type of the fourth are not rare; the a type of the fourth
is the scarcest.

Twinning according to the Carlsbad, Manebach, albite, and
pericline laws has been observed. There are two or more different
types in combination. The albite and pericline types occur poly-
synthetically, while the Carlsbad type occurs in combination with
one or both of these. The Manebach is only found in the tabular
crystal parallel to P, mostly combined with pericline twinning.
The specific gravity measured by the Westphal’s balance in
Thoulet’s solution is 2.759.

Optical characters.—Extinction angles on P(oor) and M(oro),
measured on cleavage pieces, are —36° 54’ and —35° 24’, respec-
tively. The measurement of the mean index of refraction was
made approximately by means of Wright’s solution. The solution
corresponding to the mean refraction of the mineral was deter-
mined on the Abbe total-reflectometer. The result is 2)=1.5785.
The measurement of orientation of the optic axis B was made by
the Becke method,’ with single screw micrometer ocular. The
values p and ¢ of the axis B were measured on three thin slices
parallel to P(oor). The results are as follows:

(r1) On +P(oor)

Micrometer { p= —60° 44.8’ Micrometer } p=+28° 12.6’
parallel (| r= o. 405 diagonal | r= 0.337

(2) On +P(oor)

Micrometer p=—6o0

Micrometer p=+25° 5°
parallel

r= 0.346 diagonal (7= 0.318

(3) On —P(oot)

Micrometer ( p=+55° 28.5’ Micrometer | p=—20. 11’
parallel r= 0.354 diagonal (7= 0.354

* Becke, “Bestimmung kalkreicher Plagioklase durch die Interferenzbilder von
Zwillingen,” T'schermaks Min. Mitth., 1895, Bd. 14, s. 415-42.

NOTES ON SOME IGNEOUS ROCKS OF JAPAN 643

From the above figures, the following values for the azimuth of
the axis B against the edge P/M on P (&) and the true angle-
distance (@) are given:

g w

(1) me 10037

(2) —12.3° IQ 14’

(3) —12.7° tg 42’ reduced on +P
—12.3° LO. 30.

For calculation of , my=1.5785 and k=o.141 were adopted as
the mean index of refraction and Mallard’s constant, respectively.
From the mean values of € and @, ¢ and A were given as follows:

I II
Oa On 3e Oe
A= —5.8° —4° 23/

The values under I are results approximately obtained by the
construction of the stereographic projection and those under II by
calculation.

Plotting the latter values
on Becke’s diagram, which
indicates the relation between
-the orientation of the optic
axis B of plagioclase and its
corresponding chemical com-
position, the composition of
the present mineral would be
i@entitied as Ab,Anjg—
Ab;An,;, aS shown in Fig. 12.

The mineral is optically
negative with r as the acute
bisectuxe the optic ‘angle
measured in cedar oil (ny=

Fic. 12.—In the figure, A is the anorthite
from Vesuvius, B is the anorthite from

1.515) with yellow light, is Tarumai, and C is the bytownite from
2Ha=go° 11.5’ Naeroedal.
and its true angle is
Nia Sou esr

Chemical characters —The mineral is easily attacked by hydro-
chloric acid, and the powdered sample is readily decomposed with

644 Se KOAG.

the separation of gelatinous silica in slightly hot hydrochloric acid
of the strength of 22 per cent.

The chemical analysis was made by W. Yasuda in the chemical
laboratory of the Imperial Geological Survey of Japan. The
sample for the analysis was taken from the clear and fresh part of
a crystal, and powdered to grains one millimeter or smaller in
diameter. ‘To remove the impure parts, which contained inclusions
of olivine, magnetite, and glass, the grains were separated into
three portions by Thoulet’s solution, having specific gravities of
2.747 and 2.760. The analysis was made of the sample with the
specific gravity lying between the two values. The result is as
follows:

NOH LO Pesaran aieiiey ities i mers Gent tend ec URA a GP Kueh 43.51
INU O SF syaet is oats teas ve eta etic tea eee ee BGs
| Sed Ramee areas Spee emcee NOU ue ges UN et rs ON trace
DY) a @ Riera es Wee amen ise era w Wsee anu etary peldbetsEN os Tak
LOE OEE aN eet ee ea ae SO ca oh end a uri tts 19.48
TINIE ES © tesa tre ae Onan tamara cae Ee ek rei 0.61
TE ea aN tata ceag leara gs aN peace Oy a 0.05

100. 53

Subtracting silica and magnesia corresponding to the olivine
molecule, and potash as impurity, and calculating the remainder
as parts in 100, we have:

W (percentage) Mol. prop.
SiO secre ane BBS 3 On coer Ge Hee ee 6.73)
TaN © Naieme lien nla eect ina BONA Tia aes Laon ies ere cha 0.36
CaOn: rile My diets areata pen eeae Sa 0.35
INacO RE Ree erwaten: ONO Qua eat warn nears 0.01
100.00

From which it is found that the composition of the anorthite may
be represented as a mixture of 2Ab and 35An, or Ab, , Any, ;, which
corresponds closely to the value determined optically as Ab; Ang;
pee ANge.

FACTORS INFLUENCING THE ROUNDING OF SAND
GRAINS

VICTOR ZIEGLER
South Dakota State School of Mines

CONTENTS
INTRODUCTION

THe MOLECULAR FoRCEs OF LIQUIDS
MOLECULAR FORCES AND TRANSPORTATION

METHODS OF ROUNDING
Summary of Previous Work
Experimental Work

SUMMARY
INTRODUCTION

In 1910, while discussing the rounding of sand grains with
Professor A. W. Grabau, it seemed to the author that the influence
of viscosity was not sufficiently emphasized in the literature on
that subject. Subsequent discussion with Professor C. P. Berkey
suggested this investigation. The thanks of the author are due to
Professor James F. Kemp, and especially to Professor C. P. Berkey
for many kind and valuable suggestions.

THE MOLECULAR FORCES OF LIQUIDS

For a clear understanding of the forces acting on a particle
submerged in water it is necessary that we review briefly a few of
the elementary definitions of physics. This can most clearly be
done by means of an illustration.

If we look carefully at the surface of a glass of water, we notice
that it is not horizontal but curves upward at the sides of the con-
taining vessel as though attracted by it. If we dip a clean glass
rod in water and remove it, we shall see adhering to it a thin film
of water. Upon slightly shaking the rod this film will be dis-

645

646 VICTOR ZIEGLER

lodged and in falling will assume a more or less spherical form.
The smaller the drop, the more perfect its spherical shape. Here
we have a homely demonstration of the forces acting on the liquid.
The creep-up of the water on the sides of the glass is due to the
attraction of the glass for the water; the drop of water remaining
on the glass rod is held there by the same force, that is—adhesion.
In falling, the water from the rod does not fly off in a series
of small particles, but assumes a spherical shape because the
component particles of water, or, in other words, its molecules
are attracted toward each other. Thisis cohesion. Adhesion is the
attraction of unlike molecules for each other; cohesion is the
attraction exhibited between molecules of the same substance.:
The force due to the cohesion of the molecules of different substances
and that due to the adhesion between the molecules of different
substances varies. ‘The cohesion of water is less than its adhesion
for glass, hence the glass rod is enabled to tear away a certain
amount of water.? If, however, we dip a glass rod into mercury
and withdraw it, nothing will adhere, because, in this case, co-
hesion is the stronger force.

The space through which cohesion is active is the “sphere of
molecular attraction.”’ Itisasphere about 0.00005 mm. in diame-
ter.3 If we now assume that a liquid is made up of a number of
layers of molecules, we will see that the top layer, the free sur-
face, will be attracted unequally because part of its ‘sphere of
molecular attraction” lies outside the liquid.‘

In Fig. 1 xy is the surface of the liquid. A and B represent
two molecules in the surface and beneath the surface respectively.

The circles surrounding them represent

all directions by the molecules falling
within its sphere; in the case of the mole-
cule A, however, the attraction will be downward, as the attract-
ing molecules only occupy that part of the sphere lying within

Bigs

t Nichols and Franklin, Elements of Physics, 124.
2 F, Pockels in Winkelman’s Handbuch der Physik, I, 882.
3 Duff, Textbook of Physics, 146. 4Ibid., 147.

THE ROUNDING OF SAND GRAINS 647

the water. On this account the surface of the liquid is in a state
of tension, and in order: to move the molecule B to the surface
we would have to overcome this force. We may liken the con-
dition of the surface of the liquid to that of the stretched rubber
membrane of a ball. We have a pressure at right angles to the
surface, capillary pressure, causing a tension parallel to the sur-
face, surface tension.?

Let us now consider a grain submerged in a liquid and let. us
note the action of the different forces upon it. The body will be
pulled down by the force of gravity, the magnitude of the pull
being determined by the difference in the specific gravity of the
solid and the liquid. If we consider water, then the force will be
equal to vg (d—1); where vis the volume, g the acceleration due to
gravity, and d the density of the solid.

In moving through the liquid, the grain will carry down a thin
film of water held by adhesion. There is a certain friction devel-
oped in this movement which will not be friction between the
grain and the water, but friction of water with water. The friction
developed by a thin film of water sliding on water is “superficial
viscosity.”’ The term ‘‘skin friction” is also applied to it.2 This
is the friction especially considered in the flow of water through
pipes and conduits. In addition, through the downward move-
ment of the grain, the shape of the liquid is disturbed. Any
disturbance or change of shape in a liquid calls forth a resistance,
“viscosity.’’ But even if the particle were moving in a “perfect
fluid,” 1.e., a fluid without any viscosity, its energy would gradu-
ally be dissipated in forming waves.

To summarize then, a body moving through water must over-
come resistance due to three causes; (1) viscosity, (2) skin-
friction, and (3) wave-resistance.

If we take a case in which the liquid has a definite velocity,
the conditions as outlined above will not change. In this case
the grain will be acted on by a force which is the resultant of the
velocity and gravity, and will have the direction of the diagonal

t Ganot, Physics, 122.
2 Basset, Elementary Treatise on Hydrodynamics, 52.
3 [bid., 51.

648 VICTOR ZIEGLER

of the parallelogram of forces constructed with velocity and gravity
as sides (Fig. 2). The grain will experi-
ence no resistance in the direction of the
velocity, as it will simply move along
with the water. The downward move-
ment will experience the same resistance
as though the liquid were at rest.

MOLECULAR FORCES AND TRANSPORTATION

Sediment is transported by water in one of three methods.
It is either floated on the surface, or rolled along the bottom, or
carried in suspension.

Small grains, when carefully sifted over the surface of water,
float, due to the fact that their weight is not sufficient to overcome
the surface tension of water. Since surface tension may be defined
as the ‘“‘force tending to make a liquid contract to the smallest
area admissible,” it will have the tendency to drive the floating
grains together.t This apparent attraction of grains into patches,
although not explained, has been noted by James C. Graham and
F. W. Simonds, who described this method of sand-transportation
as occurring on the Connecticut and Llanos rivers respectively.?
Experiments carried on by Simonds seem to show that if the
launching be favorable, about 40 per cent of the component grains
of most sandstones will float on water. Floating patches of sand
and dust have been noticed by the author on the Iowa and Cedar
rivers on still days during the summer, where they look essentially
like floating patches of scum or foam, and also on the quiet
water along the shore of the North Sea, near Otterndorf and
Cuxhaven in Germany. While the condition necessary for the
transportation by flotation are somewhat unusual, this method still
appears to have more importance than is usually attributed to it.

The floating of the grain depends on two molecular forces,
viz., cohesion and adhesion. Cohesion causes the tension in the
free surface of the water, and resists all attempts to break this
surface. Adhesion serves as a modifying factor. If the adhesion

t Duff, op. cit., 146.

2 Graham, A.J.S., series 3, XL, 476; Simonds, Am. Geol., XVII, 20.

THE ROUNDING OF SAND GRAINS 649

between the grain and water be strong enough to wet the grain,
it will sink at once; if adhesion be weak, the grain will remain
dry and float. The adhesion between the grain and the water
may be entirely destroyed by coating them with oil. The so-
called “‘oil-flotation process” of ore dressing depends to a great
extent on this principle. The finely pulverized ore is mixed with
a small quantity of oil. The metallic sulphides, such as galena,
chalcopyrite, and sphalerite, have strong adhesion for oil, and are
readily coated, while the quartz and other gangue remain free,
unless an excessive amount of oil is used. When the ore is allowed
to slide into the settling tanks, the gangue sinks readily, but the
coated sulphides float off. Here it seems that molecular forces
cause flotation rather than the decrease in specific gravity due to
the combined weight of oil and mineral. As the specific gravity of
the oil taken is approximately o.8, in the case of galena the volume
of oil to mineral would have to be in the ratio of 32 to 1, to bring
the density of the combined material down to that of water.t

Sharp, angular grains float more readily than those of spherical
shape. This is due to the fact that the force due to the surface
tension increases with an increase in the surface area exposed to
it. The more nearly spherical a grain, the smaller the ratio
between the surface area and the mass of the grain, and hence
the greater the ratio of weight’ to surface tension. Irregularity
of shape increases the ratio of surface to mass, and hence decreases
the tendency to break through the surface of the film.

The power of water to carry material in suspension depends
on a number of factors, some of which are: the shape, size, and
composition of the particles; the viscosity, composition, and ve-
locity of the water; the presence of colloids; the character of the
river bottom; the course of the stream, etc. The size of grain
carried depends directly on the velocity. The more irregular the
shape, the greater will be the resistance encountered in settling.
The presence of colloidal substances causes rapid settling. Again
there may be a change in the composition of the water causing an
interaction with the sediment, such as the precipitation of alumina

t Adams, M. and Sc. Press, May 7, 1904,.etc.

2F. W. Clarke, Data of Geochemistry, 430 (Bull. 330, U.S.G.S.).

650 VICTOR ZIEGLER

by the carbonates of calcium and magnesium, and a consequent
settling of the silt.t The presence of salts, alkalies, and acids in
solution hasten the rate of precipitation. However, Wheeler
arrives at the conclusion that there is practically no difference
in the rate of settlement of sand and silt in salt and fresh water.”
When the particles are very fine, as mud and ooze, the rate of
settlement is slightly faster in salt than in fresh water. Others
have shown that settling is far more rapid in salt than in fresh
water, and attribute this fact to a chemical interaction between
the salt water and the sediment, carried in this case as a colloid.
There is reason to doubt this explanation, and the more rapid
settling in salt water seems to be due to a decrease in the viscosity
of the water.4. Rough and irregular river bottoms and swinging
meanders tend to keep the water in a stirred condition and hence
aid in holding material.

METHODS OF ROUNDING

Sand grains are reduced in size by collision and friction. Hence
we know that the wear of a grain depends on a number of factors,
such as hardness, weight, distance of travel, cleavage, tenacity,
velocity of movement, etc. The rounding of sand grains under the
varying conditions has been ably discussed from the geological
standpoint by McKee’ and Goodchild. The movements of solids
through fluids have been investigated from the mathematical stand-
point especially by Basset? and Allen.’ This feature has also
been noted to some extent by Blake,? Walther,’? and Barrell."

‘E,W. Hilgaard, A.J.S., 1873, p. 288; 1879, p. 205.

2W.H. Wheeler, Nature, June 20, toot.

3 See F. W. Clarke, Bull. 330, U.S.G.S., and H.S. Allen, Nature, July 18, 1901, for
bibliographies.

4J. F. Blake, Geol. Mag., Decade IV, Vol. X, 12; W. B. Scott, Introduction to
Geology, 141; Carl Barus, Bull. 36, U.S.G.S.: Chamberlin and Salisbury, College
Geology, 3106.

5 McKee, Edinburgh Geol. Soc., VII, 208. ® Goodchild, ibid., 208.

7 Basset, Elementary Treatise on Hydrodynamics.

8 Allen, Phil. Mag., 1900.

9 Blake, Geol. Mag., Decade IV, Vol. X, 12.

to Walther, Das Gesetz der Wustenbildung.

™ Barrell, Jowr. Geol. (1908), XVI, 150.

THE ROUNDING OF SAND GRAINS 651

Summary of previous work.—McKee in his work evolves the

formula
size X specific gravity X distance traveled
R« ;
hardness

where R is the rounding (or the wear).
Considering a cube with the edge x, the distance traveled
would be roughly proportionate to the number of times the grain

D
turned over, hence me could be placed instead of distance. The

weight of the cube would be «3 Sp. Gr.
Substituting in the above equation we have

x3 Sp. Gr“
* hardness —
reducing to
R ae Sp. Gr. d
4h
Or in more general terms—
a2: op. Grd

R«

where m is a constant depending on the shape of the grain. m
is 4 in the case of a cube, 3.1416 in the case of a sphere, etc. If
the grain is under water allowance must be made and

oe - (Sp. Gr.—1) -d

IK mh

Goodchild goes farther and determines a general limiting con-
dition to the wear taking place. His work may be summarized
as follows:

Since the sand is completely surrounded by a film of the water
in which it is submerged, it will be acted on by surface tension.
By decreasing the size of a particle we increase the ratio of area
to volume, and hence to weight. Since the surface tension of
water will act over the area exposed, its magnitude compared to
the weight of the grain will increase with decrease in size. Finally,
he assumes that a balance between weight and surface tension
will be reached, such that no further rupture of the film of water
surrounding the grain can take place, and hence all wear will

652 VICTOR ZIEGLER

cease. Thus Goodchild concludes that the factor limiting the

amount of wear possible on submerged bodies, is surface tension.
Experimental work.—As stated before, in the movement of

bodies through water resistance due to three causes must be

EXPERIMENTS
mm. Diam. Glycerin Water Alcohol
Cassiterite (6.4)*
Bao eae at at nen Collision Collision Collision
De Tanai aa a eee ee Collision Collision Collision
Te oie cue cael cua ? Repulsion ? Collision Collision
Ca ham ok Renee ie. Repulsion ? Collision ? Collision
ae a meme tine pan eee Repulsion Repulsion ? Repulsion ?
Chromite (4.5)
BD ee eg sh eae RAR Repulsion Collision Collision
Peel n a aen this eaineney eeeteey c Repulsion ? Collision ? Collision
De etic een ae ee Strong Repulsion | Repulsion Collision
CAS Stren ene eon aren Strong Repulsion | Repulsion ? Repulsion ?
ae ERI cet ae ile re Strong Repulsion | Repulsion ? Repulsion ?
Quartz (2.65)
BD Ue aoe aa Collision Collision Collision
peer te tie NL Peed Vir Shs ee ? Repulsion ? Collision Collision
hee a A nel ee aD eo Repulsion Repulsion ? Repulsion ?
le CRE et re WEN inter we Repulsion Repulsion ? Repulsion ?
Gypsum (2.35)
BO. tensa a eC ura Collision Collision Collision
QT a's is gh aa eee ? Repulsion ? Collision Collision
Tee ed ae flaps ae ? Repulsion ? Repulsion ? Collision ?
Cain ach Gen ete ? Repulsion ? Repulsion ? Repulsion P
rae NU pra ? Repulsion ? Repulsion Repulsion
Anthracite (1.6)
rar ae RA rete ee alle cee aR eatte ia Collision Collision
Dea ge cl haere ge on (ea rae rare cree ? Collision ? Collision
it el Caer ee ene Sate Nola Slo CEMA eee Repulsion Repulsion
ra See renee ciate Wo cnc eite an 4 oe Repulsion Repulsion
Raa PAOD Raia! sie tash l= Ras eiea mae ote te orate Repulsion Repulsion
* The figures beside the minerals represent specific gravity.
DATA
|
| Sp. Gravity Surf. Tension Viscosity
Gly cerinyets sgn atin one Taig 66.5 8.0
Warten it aie ahead else ae TO) FR .10
Nl eoholAeatine nh. ce eerie 887 23.4 .OIL
overcome, viz., viscosity, skin-friction, and wave-resistance.

Unless these three factors are overcome, grains cannot collide.

THE ROUNDING OF SAND GRAINS 653

The effect of surface tension, however, is one aiding wear, since
it tends to draw grains together in its effort to force the water to
assume the least area permissible under the conditions to which
it is subject. Thus viscosity, since it is the most potent of the
three factors mentioned, limits the minimum size to which wear
takes place. The energy of the particle must overcome the viscos-
ity to allow collision. Since the velocity of different grains in
water is roughly equivalent, their energy varies directly with the
size, the larger grains only having enough power to overcome
viscosity. In the case of small grains the water acts as a cushion
preventing actual collision, or checking the velocity of contact.
To show the action of viscosity in preventing collisions of grains
the following experiments were performed.

Grains were dropped down long glass tubes filled-with liquids
of different viscosities, and the action at the meeting of the grains
was observed. Grains of different specific gravities .
were taken so as to overcome the difference in the
specific gravities of the liquids. 4

Again an experiment was performed (Fig. 3) A
in which the glycerin was allowed to run from the
reservoir C through the tube AA down which the
different grains were dropped. The results were
practically identical with those above.

It will be noted that the surface tensions of A
water and glycerin are nearly the same, but that Fic. 3
the viscosities are in the ratio of eighty to one.

In the case of glycerin it was apparently impossible for the grains
of small diameter to collide. Whenever a larger grain would over-
take a smaller and slower falling one, there was an apparent repul-
sion between the two as they were held apart by the viscosity.
In small and light grains the repulsion appeared violent so that
often a clearing space of a quarter of an inch was shown by grains
that apparently were going to collide. As can be seen from the
table, in the case of water the protection against collision was
much less. Small grains of quartz, less than 1 mm. in diameter
showed fairly strong repulsion, but above that size collisions were
the rule. Again in the case of alcohol, with a surface tension of

654 VICTOR ZIEGLER

23.4 and a viscosity of o.o11, repulsion was only noticed in the
finest grains.

SUMMARY

The results of these experiments seem to show that viscosity
is the factor protecting grains from wear. Viscosity will not
only prevent the wear of the smaller grains, but it will also act
as a buffer and will greatly lessen the velocity of grains when about
to collide with each other or with the bottom of the river. In
view of the results it seems improbable to the writer that grains
less than 0.75 mm. in diameter could be well rounded under water.
Well-rounded grains of about this and smaller diameter appear
to be the result of wind work, in which case the protecting factor,
viscosity, would be practically zero, so that there would be no
limit to the minimum size attainable by wear.

THE UNCONFORMITY BETWEEN THE BEDFORD AND
BEREA FORMATIONS OF NORTHERN OHIO?

WILBUR GREELEY BURROUGHS
Oberlin, Ohio

In Lorain County of northern Ohio, 30 to 4o miles west of
Cleveland, occurs a striking unconformity between the Bedford
and Berea formations. In Ohio the Bedford formation is the low-
est member of the Waverly group, Mississippian system. It is an
argillaceous shale, the lower portion being a dark bluish gray, the
upper portion a chocolate or dark red color. The Berea formation
above is a bluish-gray, fine-grained sandstone.

STRUCTURE OF THE BEDFORD AND BEREA FORMATIONS

Dynamic movements of the region have taken place since the
laying-down of the Berea sandstone, both formations being uni-
formly folded. The general structure is that of a syncline whose
axis runs northeast and southwest.- The red Bedford shale comes
to the surface on either side of this trough, which averages about
two miles in width. A great deal of the sandstone in the syncline
itself has been eroded away, exposing the red Bedford shale beneath.
The large rock trough contains minor anticlines and synclines, with
axes parallel to that of the large syncline. A compressional force
from the east and west has folded the axis of the northeast-
southwest syncline into a series of anticlines and synclines. At
South Amherst, in the region under discussion, the axis of the large
syncline is plunging toward the east.

LENSES OF BEREA SANDSTONE IN THE HORIZON OF THE BEDFORD
SHALE

The Bedford forms steep banks where the streams cut against

it. As one goes along Beaver Creek, which flows just east of the

«The writer wishes to thank Professor G. D. Hubbard, of Oberlin College, for
criticism of the manuscript. The work was done in the Department of Geology at
Oberlin College.

655

656 WILBUR GREELEY BURROUGHS

Berea sandstone quarries at South Amherst, or Chance Creek on
the west, he will occasionally find the high banks covered by a
mass of Berea sandstone talus. This débris came from a lens of
sandstone im situ at the top of the bank, extending for 50 to 100
feet on the horizontal, and flanked on either side by red Bedford
shale. In places the sandstone is in thin beds 2 to 3 inches thick,
at other places in massive beds 3 to 4 feet thick. The lenses range
from to to so feet in total thickness. Their long axes run ina
general westward direction. No evidence of slumping is found in
connection with the banks at and in the vicinity of these lenses.
Neither can they be the bottom of synclinal troughs, for the dips
_ of their minor axes are not great enough to bring the sandstone to
the top of the bank of Bedford shale. The only answer to the
question of their origin is that there were once channels and depres-
sions in the Bedford shale which, on being filled with sand, ulti-
mately formed (in cross-section) the lenses as they now exist.

So far as the writer is aware, nothing has ever been published
regarding this unconformity between the Bedford and Berea forma-
tions of northern Ohio, save in the Ohio Geological Survey Report,
Vol. II, published in 1874. This report mentions lenses in the
horizon of the Bedford shale north of Elyria, which is to the east-
ward of the region under discussion in this article. On p. 91 we
read, referring to the erosion of the Bedford prior to the deposition
of the Berea: ‘It is probably due to this fact that the red shale is
so frequently found to be wanting in the section.”

Mr. H. E. Adams, superintendent of the Ohio quarry at South
Amherst, Ohio, states that in the extreme southeast corner of
Lorain County, Berea grit occurs in lenses in the horizon of the
red Bedford shale exactly in the same manner as at South Amherst.

The Bedford-Berea unconformity is not confined to Lorain
County, Ohio. Dr. Hubbard is authority for the statements that
‘an unconformity occurs at the same horizon in: northwestern
Fairfield County near Lithopolis; and Professor Prosser believes
a similar break exists at the same horizon near Cleveland, Ohio,
but further work is there necessary.”

The sand-filled troughs in the erosion plane of the Bedford
formation which are visible along the streams are small and insig-

UNCONFORMITY OF BEDFORD AND BEREA FORMATIONS 657

nificant in comparison with the channels and valleys whose exist-
ence is made known by the drill of the quarry-men.

The deepest of these sand-filled depressions is that in which is
located the quarry of the Ohio Stone Company (Fig. 1). This
quarry is situated on the outskirts of South Amherst, Lorain

BIG

Horizontal and vertical scale - - - - line H-S=4o0 feet. ----N=North. Line
A-D=elevation of 600 feet above sea-level. B=Bedford shale. Bs=Berea sand-
stone. G=glacial drift. O=Ohio quarry. M=Malone quarry. C=No. 6 quarry,
Cleveland Stone Co.

County, Ohio. The pit has been sunk along the axis of an anti-
clinal fold which runs in a southwesterly direction. The anticline
plunges eastward with a dip of 3°. The south flank of the fold in
the quarry has a dip of 6° to the southeast; the north side dips 7°
northwest. The great thickness of the sandstone, 217 feet, is due
to the sand-filled channel of the eroded Bedford horizon. That
this is true is shown by drillings and the structure of the strata in
the vicinity. One hundred feet southwest of the edge of the quarry
on the same level as the top of the quarry pit, the drill went 60
feet thorugh glacial drift and came upon Bedford shale without
encountering any sandstone, and yet the strata in the pit were
dipping in that general direction. In the quarry 217 feet of sand-
stone were passed through before striking Bedford shale. Four
hundred feet on the horizontal from the north side of the quarry
the strata dip toward the southeast. One thousand feet on the
horizontal from this north side of the Ohio quarry, and on the same
level as the top of the quarry, another quarry, the Malone, has
gone down roo feet through massive sandstone to the Bedford shale.
Here the strata still dip to the southeast; the dip is 7°. Thus a
small syncline lies between these two quarries. The dips of the
strata are not great enough to carry the sandstone to the depth
reached in the Ohio quarry even though the syncline did not exist.

658 WILBUR GREELEY BURROUGHS

Therefore the Ohio quarry is located in a depression of the eroded
horizon of the Bedford shale. The Ohio pit is 175 feet wide, yet
neither bank of the Bedford channel in the quarry has been reached.

By drill and well records, the writer has traced this channel, in
which is the Ohio quarry, for a distance of three and one-half miles
to the southwestward where it outcrops on the steep valley slopes
of a stream known as Chance Creek. Here the lens of sandstone
is 50 feet wide and 15 feet thick. On both sides and at the bottom
the sandstone lies directly against the red Bedford shale. The
decreasing of the channel in depth and width as it went south-
westward indicates that the stream flowed from the southwest
toward the east.

Beaver Creek flows a little less than one-half mile east of the
Malone quarry. Here no sandstone is found along the banks, in
spite of the fact that the axis of the anticline is plunging in that
direction at an angle of 3°. The outcrops of Bedford shale at this
place on the creek are 30 to 4o feet lower in elevation than the top
of the sandstone at the Malone quarry, where the sandstone is 100
feet thick. Still, if the Malone quarry deposit of Berea grit is not
a sandstone-filled depression in the Bedford shale, the sandstone
should outcrop at Beaver Creek, which it does not do. This quarry
therefore also.is located in a lens of sandstone in the horizon of the
Bedford shale.

A short distance farther north of the Malone quarry is No. 6
quarry of the Cleveland Stone Company. Structurally this quarry
is on the southward-dipping flank of an anticline whose axis runs
in a southwesterly direction. The average dip is 8°. The axis
itself is folded into a low, small anticline in the west portion of the
quarry. Here, as elsewhere in the region, the sudden great thick-
ness of sandstone cannot be accounted for save as a sand-filled
channel of the eroded horizon of the Bedford shale. Although the
long axis of No. 6 quarry does not exactly coincide with the direc-
tion of the channel in which it is located, yet, both being in nearly
the same westerly direction, the size of the pit gives some idea as
to the size of the valley in the Bedford formation. The quarry is
2,632 feet long, has an average width of 460 feet, and a depth of
from 100 to 175 feet.

UNCONFORMITY OF BEDFORD AND BEREA FORMATIONS 659

BLUE SHALE AT THE UNCONFORMITY

In the bottom of all these deep channels in the horizon of the
red Bedford shale is a soft, dark-blue shale, three to four feet thick.
This blue shale is not found beneath the sandstone of the small
lenses in the Bedford horizon, nor is it found at any given horizon.
The bottoms of the quarries are at different depths with the dip of
the strata too slight to bring this blue shale to all the quarry floors.
The outcrop of the Ohio quarry channel on Chance Creek had no
blue shale beneath the sandstone, the sandstone resting directly
upon red Bedford shale. Yet this blue shale is found underlying
the sandstone in the Ohio pit.

The reason for the location of this blue shale may be the follow-
ing: The lower and deeper portions of the valleys of the Bedford
streams became drowned. Sediment carried by the rivers into
these quiet bodies of water was deposited and eventually formed
this blue shale which occurs between the red Bedford shale and the
Berea sandstone.

Dr. Hubbard and the writer made a careful search for fossils in
this blue shale, but none were found.

CONCLUSION

Starting a few miles east of Sandusky, Ohio, and extending
eastward to Cleveland, Ohio, there is a well-defined unconformity
between the Bedford and Berea formations. The unconformity,
however, extends over a greater area than the region above defined,
as it has been noted as far south as Fairfield County, Ohio.

During the period that the Bedford horizon was above the level
of the sea, its surface was dissected, streams cutting deep channels
and wide valleys. The lower portions of these valleys became
drowned. In the quiet water thus formed, the rivers deposited
sediment which later became a blue shale, logically belonging to
the Berea formation.

The entire Bedford land area gradually was submerged, and the
Berea sandstone formation was laid down.

TDI LOR AY

In recent years there has been a notable increase in the desire for
the use of photographic illustrations on the part of authors of
articles submitted to the Journal. To an increasing extent such
use is coming to be more than a merely helpful or ornamental acces-
sory; it is often an essential means to an adequate presentation of
results. In a like manner there has been a marked growth in the
use of maps, sections, diagrams, and other graphic matter, as also
of analyses, computations, statistics, and similar matter assembled
in tabular and diagrammatic forms. It seems inevitable that the
proportion of these classes of relatively expensive matter will con-
tinue to become greater. To this imperative increase in the expense
of properly illustrating the matter of the Journal, there is added the
greater cost of printing and publishing resulting from the general
advance in prices. To meet the demands of these changed condi-
tions, it has been decided to raise the price of the Journal to sub-
scribers, beginning with the twentieth volume, except that current
subscribers may renew their subscriptions for one year at the present
rate if they do so previous to July 1, 1912. Details may be found
in the Publishers’ notice in the advertising section of this issue.

LAC ye:

660

REVIEWS

Ueber Erythrosuchus, Vertreter der neuen Reptilordnung Pelyco-
simia. By F. vON HUENE. Geologische und paleontologische
Abhandlungen, X (1911). Pp. 58; plates rr.

The genus Erythrosuchus was described five years ago by Dr. R.
Broom, from the Triassic of South Africa; it was referred by him to
the Phytosauria, from which it differs especially in having terminal
nares and short premaxillae. Dr. Heune, after a careful study of the
known remains of the genus, reaches, in the above-cited paper, the
startling conclusion that the genus represents a new order of reptiles
allied to the Pelycosauria; that is, that it is a branch from the root-
stem of that group (“Zweig von der Wurzel der Pelycosaurien”’).
Aside from the differential characters already mentioned, Erythrosuchus
differs from the phytosaurs chiefly in the structure of the limbs, which
seem to resemble more those of the pelycosaurs and other primitive
reptiles. The skull, as Huene admits, has “viele und auffallende
Ubereinstimmungen mit den Phytosaurien,’’ in its two temporal
vacuities, the absence of additional temporal bones, antorbital vacui-
ties, etc. The vertebrae also, are of the archosaurian type, differing
especially from those of the Pelycosauria in the shallow concavities of
their centra, the absence of intercentra, and especially in the articula-
tion of the dorsal ribs. It is an important fact, which the author does
not seem to appreciate, that the mode of rib articulation is highly
characteristic of the reptilian orders. It may be set down as a funda-
mental taxonomic principle that no related groups of reptiles, or other
vertebrates differ materially in the way in which the dorsal ribs articu-
late with their vertebrae. All the archosaurian reptiles are alike in
this respect—double-headed ribs articulating with the diapophyses of
the arches exclusively, at least posteriorly—a character found in no
other vertebrates. And this is the condition in Erythrosuchus, a char-
acter in itself sufficient to fix its position among the Archosauria, and
by Archosauria I mean the Crocodilia, Dinosauria, Pterosauria, and
Parasuchia. The Sauropterygia, it is true, also have the dorsal ribs
attached exclusively to the diapophyses, but the ribs show no division
into capitulum and tuberculum, differentiating the order sharply.
Under the Sauropterygia I include only the Nothodontia and Plesio-
sauria—the Mesosauria, which are sometimes included in the order,

661

662 REVIEWS

belong, I am satisfied, with the Theromorpha. The Pelycosauria, like
other primitive reptiles, have the ribs attached invariably to the inter-
central space and the diapophysis; that is, they are double-headed
throughout, while the Cotylosauria, with like attachments, may have
the articulation continuous from head to tubercle.

In the pectoral girdle about all the difference that Erythrosuchus
presents from the phytosaurs is a distinct supracoracoid foramen—
precisely the character that would be expected in the more primitive
form; and the pelvis, while agreeing in the main with the phytosaurs,
differs very materially from that of the pelycosaurs. The chief differ-
ences that the author finds allying the genus to the pelycosaurs, are,
as stated, found in the limbs: “ Erythrosuchus kann, trotz der vielen
Ahnlichkeit iiberhaupt, kein Parasuchien sein, da das Femur besonders
in der Bildung des Proximalendes mit den primitiven und 4lteren
Pelycosaurien und Cotylosaurien . .. . vollig iibereinstimmt.” Ad-
mitting this ‘‘complete agreement” of the proximal end of the femur
between Erythrosuchus and the Pelycosauria and Cotylosauria, can one
not conceive that the resemblances have been brought about by
adaptation to like conditions, that the characters are adaptive and not
genetic here, as so often elsewhere? But I do not admit this complete
agreement. There is much variation in the femora of the cotylosaurs
and pelycosaurs, as witness those of Dimetrodon, Araeoscelis, Diadectes,
Seymouria, and Labidosaurus. The humerus of Erythrosuchus, although
it has a large lateral process and greatly expanded ends, differs materi-
ally from that of the pelycosaurs and cotylosaurs in the absence of the
entocondylar foramen. One does not refer the moles to a distinct
order of mammals because of the differences in the humeri from other
rodents.

The skull structure of Erythrosuchus, with its upper temporal and
antorbital vacuities, is so much at variance with the theromorph rep-
tiles, that I can see no possible evidence of genetic relationships between
them. Unless Huene would make the Archosauria a part of the same
branch, from the root of the Pelycosauria, he attempts to prove too
much, for he would make the Pelycosimia a distinct branch or phylum
of the reptilia and entitled to more than ordinal distinction. He classes
the Pelycosauria with the single-arched reptiles and is correct in so
doing, but I confess I am not quite clear as to the real distinctions
between upper and lower temporal vacuities in such reptiles. Nor
does Huene seem to be either, as witness the following quotations:

Op. cit. page 41, second paragraph: ‘Da bei Deuterosaurus das

REVIEWS 663

Postorbitale den unteren Rand der einzigen Schlafenéfinung begrenzt,
ist sie als die oberen aufzufassen, und sie sind, im Gegensatz zu den
ebenfalls monozygocrotaphen Pelycosaurien und Therapsida als ‘hypo-
zygocrotaphen’ zu bezeichnen.”’

Same page, fourth paragraph: ‘‘Alle Therapsida (mit warscheinlicher
Ausnahme von Cynognathus) besitzen bekanntlich nur eine einzige
Schlafenoffnung, die der oberen entspricht (italics mine). Darin und in
der Forme des Quadratums stimmen sie alle mit den Deuterosaurien,” etc.

Page 43, second paragraph: “Da die untere Schlifenéffnung nicht
entwickelt, resp. nach unten nicht geschlossen ist, fehlt den Therapsiden
das Quadratojugale,”’ etc.

Same page, third paragraph: “Da bei den Therapsiden das Postor-
bitale und Postfrontale an der oberen Ecke der Schlifenéfinung liegen,
ist letztere als untere Schlafendffnung aufzufassen, die Therapsiden
sind also katazygocrotaph.”’

From personal conversation with Dr. Huene I know that the last
statement expresses his real views; but nevertheless the flat contra-
dictions on these two pages indicate an unsettled opinion. As I have
already stated (American Permian Vertebrates, p. 92) Broom has figured
Tapinocephalus with the postorbital and squamosal in broad contact,
but he nevertheless holds that the vacuity above them is the “lower”’
one. One must therefore wait for further light on the subject before
accepting their views.

And there is much confusion also about the quadratojugal bone.
It is known to occur in only one genus of the Therapsida, Dinocephalus,
but both Broom and Huene insist that it is present in the Pelycosauria,
and Broom has figured it in Dimetrodon. But, a study of the material
in the University of Chicago—material in which this region is preserved
most perfectly—enables me to say positively that there is no such
suture or foramen in the lower arch as Broom gives. That a very small,
vestigial quadratojugal bone may occur at the extreme posterior end
of the jugal is possible, but I have never seen any satisfactory evidence
of it, and I doubt its presence, as does also Professor Case.

In brief my own opinion is that Broom was quite right when he referred
Erythrosuchus to the Phytosauria, using the term in a wide sense as a
synonym of Parasuchia. In any event Erythrosuchus is an archosaurian
reptile with no direct affinities with the Pelycosauria.

In expressing these differences of opinion I would in no wise depre-
cate the value of Dr. Huene’s paper. It is a useful one and may be
perused with profit.

664 REVIEWS

In conclusion I wish to protest against the restoration Huene has
made of my figure of the pelvis of Eubrachiosaurus Will. (p. 49). The
outlines as I gave them are essentially correct, and the bones do not
belong on the right side. As to the distinction of the genus from
Placerias Lucas, I am, however, not so sure.

S. W. WILLISTON

The Monroe Formation of Southern Michigan and Adjoining Regions.
By A. W. GraBAu AND W. H. SHERZER. [Michigan Geo-
logical and Biological Survey. Publication 2. Geological
Series 1.]

This report describes a series of Paleozoic beds and their faunas which
have their greatest development in southeastern Michigan and the
adjacent portions of Ontario and Ohio. In the past these strata, which
constitute the Monroe formation, have been much misunderstood, and
their importance in the Paleozoic section of the region has been greatly
underestimated. The maximum thickness of the formation is about
1,200 feet.

The Monroe as a whole is divided into two series of dolomitic beds,
the Lower and Upper Monroe, separated by the Sylvania sandstones,
a bed of exceptionally pure, white, and almost incoherent sand in its
more typical development, but merging into arenaceous dolomites in
its less typical expression. The maximum thickness of the Sylvania
is 300 feet, and the peculiar nature of the formation is explained on the
hypothesis that it is an aeolian deposit laid down under essentially desert
conditions, the original source of the material being the exposures of the
Saint Peter sandstone to the northwest in Wisconsin.

The Monroe faunas are described in detail and are illustrated by
twenty-five plates; 126 species in all are defined, many of them new
forms, and seven new genera are proposed. The faunas of the two
divisions of the Monroe are shown to be essentially different, there being
almost no species in common. The Lower Monroe faunas are all late
Silurian in aspect, being more or less closely related to the Manilus and
Rondout formations of eastern New York. In the lower divisions of
the Upper Monroe a conspicuous coral element appears which was
entirely lacking in the Lower Monroe faunas, and among these corals
are many strikingly Devonian forms; among the brachiopods are found
both Devonian and Silurian types; the pelecypods are Devonian while
the gastropods and cephalopods are essentially Silurian in aspect.

REVIEWS 665

Lying above the beds carrying the strikingly Devonian fauna of the
Upper Monroe, is the Lucas dolomite, the youngest member of the
series, in which the fauna is Silurian in aspect throughout.

In their correlation of the Monroe series the authors adopt a new
arrangement of the North American Silurian formations, as follows:
(1) Lower Silurian or Niagaran, (2) Middle Silurian or Salinan, (3) Upper
Silurian of Monroan. The Lower Monroe is said to be unrepresented
in either western or eastern New York, but is correlated with the so-
called “Salina”? and the lower portion of the Corrigan formation of
Maryland. The lower portion of the Upper Monroe is correlated with
the Bertie waterlime and Akron dolomite of western New York, and with
the Rosendale waterlime and Cobleskill of eastern New York. An
equivalent of the Lucas dolomite is wanting in western New York but
it is represented by the Rondout and Manlius of eastern New York and
by the Corrigan formation of Maryland.

In a discussion of the paleogeography of Monroe times it is suggested
that the faunas of Silurian aspect in the Lower Monroe and in the Lucas
dolomite have had an Atlantic origin, while the faunas with the notable
Devonian expression in the Upper Monroe below the Lucas dolomite

have come in from the north.
Se We

The Fossils and Stratigraphy of the Middle Devonic of Wisconsin.
By HerpmMan F. CieLanp. [Wisconsin Geological and
Natural History Survey, Bulletin No. XXI_]

The Devonian faunas occurring in the neighborhood of Milwaukee
and Lake Church, Wisconsin, are of especial interest to students of
Paleozoic historical geology because of their intermediate geographic
position between the much better known Devonian faunas of New York
and of Iowa. The present report by Dr. Cleland records a complete
census of these faunas with detailed descriptions of the species, accom-
panied by fifty-three plates of illustrations. Something over 200 species
are recognized. Of the total number of species 81 occur in Devonian
faunas east of Wisconsin, mostly in New York, while 48 species occur
in the Devonian of Iowa and other localities to the west. This mingling
of the eastern and western faunas of late Middle and early Upper Devo-
nian time in the Milwaukee region has been pointed out before, but here

for the first time do we have a full statement of the evidence.
S. W.

666 REVIEWS

Yorkshire Type Ammonites. Part III. Edited by S.S. Buckman.

The scope of this work has been defined in a notice of the earlier
parts. The present instalment includes the original descriptions with
additional notes by the editor, and figures of the type specimens, of
eight species, bringing the total number of species now defined and

illustrated up to thirty.
5. W.

Report on Traverse through the Southern Part of the N orthwest
Territories from La Seul to Cat Lake in 1902. By ALFRED G.
Witson. [Geol. Survey of Canada,.No. 1006.] Pp. 21.

The district traversed was wholly an area of Archaean rock (schists
and granites). Many of the granites were notable on account of the
large amount of microcline contained. Schists were mainly basic, biotite,
and amphibole schists. Glacial striae indicated a general glacial move-

ment S.W. to W.S.W.
H*C.-C,

Oil Resources of Illinois with Special Reference to the Area Outside
of the Southeastern Fields. By RAYMOND 5. BLATCHLEY.
[Bull. Illinois State Geological Survey No. 16, pp. 7-138];
Plates13, Figs; 2.

In this report the author presents a general review of the geology of
Illinois as applied to the petroleum industry. He tabulates and repre-
sents graphically a number of well records which are chosen to furnish
a series of sections running in different directions across the central and
southern part of the state. The No. 6 coal bed furnishes a key horizon,
the underlying formations lying generally parallel with it. In a few
of the better-explored areas this horizon is mapped in contour. |

eRe

Meteor Crater (Formerly Called Coon Mountain or Coon Butte) in
Northern Central Arizona. By D. M. BARRINGER. Read
before the National Academy of Sciences at Its Autumn
Meeting at Princeton University, November 16, 1909. Pp. 24;
Plates 18, Maps 3.

There seems to be no doubt that the so-called crater is the work
of a falling meteorite. The author has made a careful and detailed

REVIEWS 667

study of the whole region and finds abundant evidence which renders
any other hypothesis untenable. The question as to what has become
of the projectile still remains unsettled. There are three possibilities:
(1) that it was broken into many small pieces and thrown out of the
crater; (2) that it has disappeared within the crater through oxidation
or some other cause; (3) that it is still somewhere in some form in the
depths of the crater. The author concludes that the last is the true
explanation and that the remains of the meteorite may yet be found.

EUR,

Age and Relations of the Little Falls Dolomite (Calciferous) of the
Mohawk Valley. By E. O. Utrich AnD H. P. CusHIne.
[N.Y. State Museum Bulletin 140, Sixth Report of the Director
1909, pp. 97-140.]

To clear up some uncertainty as to the exact stratigraphic relation-
ships of the Little Falls Dolomite, a series of sections in the Mohawk
Valley were studied by the authors and described and correlated in detail.
The formation was found to be in conformable sequence with the Theresa
formation and the Potsdam sandstone below and separated by an uncon-
formity from Beekmantown beds above. The paper concludes with a
strong argument for the adoption of the proposed Ozarkian system of

which the Little Falls Dolomite is a member.
Baia.

Report of the Vermont State Geologist, r909-1910. By G. H. PER-
KINS AND OTHERS. Pp. 361; Plates 71, Figs. 31.

The report contains the following papers: “History and Condition
of the State Cabinet,” by G. H. Perkins, pp. 1-75; ‘‘The Granites of
Vermont,” by T. N. Dale, pp. 77-197; ‘‘The Surficial Geology of the
Champlain Basin,” by C. H. Hitchcock, pp. 199-212; “Trilobites of
the Chazy of the Champlain Valley,” by P. E. Raymond, pp. 213-28;
“Geology of the Burlington Quadrangle,’’ by G. H. Perkins, pp. 249-
56; “Preliminary Report on the Geology of Addison County,” by H. M.
Seely, pp. 257-313; ‘‘Asbestos in Vermont,”’ by C. H. Richardson, pp.
215-204 Mineral Resources,” by G. H. Perkins, pp. 331-52-

Eight plates illustrate the trilobites of the Chazy and ten the fauna
of the Fort Cassin beds (Beekmantown) which are found in Addison

County.
iis 15 IE

668 REVIEWS

Iowa Geological Survey, Vol. XX. Annual Report, 1909, with
Accompanying Papers. By SAMUEL CALVIN, State Geologist,
and Others. Pp. 542; Plates 42, Maps ro, Figs. 42.

The report contains the following papers: “Geology of Butler
County,” by Melvin F. Arey, pp. 1-60; ‘Geology of Grundy County,”
by Melvin F. Arey, pp. 60-96; “Geology of Hamilton and Wright
Counties,” by Thomas H. MacBride, pp. 97-150; “‘Geology of Iowa
County,” by S. W. Stookey, pp. 151-98; “Geology of Wayne County,”
by Melvin F. Arey, pp. 199-236; “Geology of Poweshiek County,”
by S. W. Stookey, pp. 236-70; “Geology of Harrison and Monona
Counties,’ by B. Shimek, pp. 271-486; ‘Geology of Davis County,”
by Melvin F. Arey, pp. 487-524.

Shimek’s report on the geology of Harrison and Monona counties
contains a detailed description of the mammalian fauna recently dis-
covered in the Aftonian interglacial deposits. These are especially
important, since in only one other instance in North America has it been
possible to determine definitely the age of a Pleistocene mammalian
fauna. Preliminary reports and descriptions of this fauna have been
published by Shimek and by Calvin in Sczence and in the Bulletins of

the Geological Society of America.
E.R. E.

Practical Mineralogy Simplified. For Mining Students, Miners,
and Prospectors. By JESSE PERRY Rowe. New York: John
Wiley & Sons, 1911. Pp. 162.

This textbook is arranged to give a few special or characteristic
properties or tests for the common minerals, that will enable persons
unskilled in chemistry or mineralogy to identify them by simple methods.
It is readable and well arranged. It will doubtless serve a useful purpose.

\Wi al 18,

IEGENG. PUBLICATIONS

—ApAMsS, F. D., AnD BARtow, A. E. Geology of the Haliburton and Ban-
croft Areas, Province of Ontario. [Canada Department of Mines, Geo-
logical Survey Branch. Memoir No. 6. Ottawa, ro1o.]

—ApaAms, J. H. The Geology of the Whatatutu Subdivision, Raukumara
Division, Poverty Bay. [New Zealand Geological Survey Bulletin
No. 9 (New Series). Wellington, roro.]

—Acassiz, ALEX. Reports on the Scientific Results of the Expedition to
the Tropical Pacific, in Charge of Alexander Agassiz, by the U.S. Fish
Commission Steamer ‘“ Albatross,’ from August, 1899, to March, 1900,
Commander Jefferson F. Moser, U.S.N., Commanding. XI. Echini.
The Genus Colobocentrotus. [Memoirs of the Museum of Comparative
Zoélogy at Harvard College. Vol. XXXVI, No. 1. Cambridge, 1908.]

—ASHLEY, GEORGE H. Outline Introduction to the Mineral Resources of
Tennessee. [Extract (A) from Bulletin No. 2, ‘‘Preliminary Papers on
the Mineral Resources of Tennessee,’ Tennessee Geological Survey.
Nashville, 1o10.]

—Ausserordentliche Sitzung der Gesellschaft fiir Erdkunde zu Berlin zur
Begriissung von Commander Robert E. Peary am 7 Mai, toto. [Sonder-
abdruck aus der Zeitschrift der Gesellschaft fiir Erdkunde zu Berlin,
Jahrgang 1010, No. 5.|

—Barrows, H. H. Geography of the Middle Illinois Valley. [Bulletin
15, Illinois Geological Survey. Urbana, roto.]

—Bonnet, R., uND STEINMANN, G. Die “Eolithen”’ des Oligozins in Belgien.
[Sonderabdruck aus den Sitzungsberichten der Niederrheinischen Gesell-
schaft fiir Natur- und Heilkunde zu Bonn, 1909]

—Bow es, O. Tables for the Determination of Common Rocks. [Van
Nostrand & Co., New York, 1910.|

—Canadian Department of Mines, Geological Survey Branch, Report of,
for the Calendar Year 1909. [Ottawa, ro1o.]

—CHILTON, CHARLES, Epiror. The Subantarctic Islands of New Zealand.
Reports on the Geo-Physics, Geology, Zodlogy, and Botany of the Islands
Lying to the South of New Zealand, Based Mainly on Observations and
Collections Made during an Expedition in the Government Steamer
““Hinemoa’”’ (Captain J. Bollons) in November, 1907. Vols. I and II.
[Published by the Philosophical Institute of Canterbury, Wellington,
N.Z., 1909. Dulau & Co., Ltd., 37 Soho Square, London, W., England.|

—CIRKEL, Frirz. Report on the Iron Ore Deposits along the Ottawa (Que-
bec Side) and Gatineau Rivers. [Canada Department of Mines, No.
23. Ottawa, 1909.]

669

670 RECENT PUBLICATIONS

—Crarke, F. W. Analyses of Rocks and Minerals from the Laboratory
of the United States Geological Survey 1880 to 1908. [U.S. Geological
Survey Bulletin 419. Washington, 1910.|

—Colorado School of Mines, Quarterly of, Vol. V, No. 4. [Golden, 1910-12.]

—Crwper, A. F. Cement and Portland Cement Materials of Mississippi.
[Mississippi Geological Survey Bulletin No. 1. Nashville, 1907.]

—Cross, WuirmMan. The Natural Classification of Igneous Rocks. [Quar-
terly Journal of the Geological Society, Vol. LXVI (1910), pp. 470-506.]

—Datt, Wm., H. anp Bartscu, Paut. New Species of Shells Collected
by Mr. John Macoun at Barkley Sound, Vancouver Island, British
Columbia. [Memoir No. 14-N, Canada Department of Mines, Geo-
logical Survey Branch. Ottawa, 1o1o.]

—Dowunc, D. B. The Edmonton Coal Field, Alberta. [Memoir No.
8-E, Canada Department of Mines, Geological Survey Branch. Ottawa,
19I0.|

—EastmMan, C. R. Devonic Fishes of the New York Formations. [Memoir
No. 10, New York State Museum. Albany, 1907.]

—ELspEN, J. V. Principles of Chemical Geology. [Whittaker & Co., New
York, 1910.]

—FARRINGTON, O. C. Meteorite Studies III. [Field Museum of Natural
History, Publication 145. Geological Series, Vol. III, No. 8. Chicago,
T910.|

—FILCHNER, W., NORDENSKJOLD, O., AND PeNcK, A. Plan einer deutschen
antarktischen Expedition. [Sonderabdruck aus der Zeitschrift der
Gesellschaft fiir Erdkunde zu Berlin, Jahrgang 1010, No. 3.]

—Geological Survey of Western Australia, Report of the Annual Progress
for the Year 1909. [Perth, 1o910.]

—GLENN, L. C. Denudation and Erosion in the Southern Appalachian
Region and the Monongahela Basin. [U.S. Geological Survey, Profes-
sional Paper 72. Washington, rort.]

—GraBau, A. W. Guide to the Geology and Paleontology of the Schoharie
Valley in Eastern New York. [Bulletin 92, Paleontology 13, New York
State Museum. Albany, 1906.|

—GRantT, U. S., anp Hiccins, D. F. Glaciers of Prince William Sound and
the Southern Part of the Kenai Peninsula, Alaska. [Bulletin American
Geographic Society, Vol. XLII, No. 10. Washington, 1910.]

—Hazarp, D. L. Results of observations Made at the Coast and Geodetic
Survey Magnetic Observatory at Baldwin, Kansas, 1905 and 1906.
[Department of Commerce and Labor, Coast and Geodetic Survey.
Washington, roro.]

—Iowa Geological Survey, Vol. XX. Annual Report with Accompanying
Papers. [Des Moines, ro10.]

—Jounson, J. P. The Stone Implements of South Africa. [Longmans,
Green & Co., New York, 1907.]

RECENT PUBLICATIONS 671

—Maryland Geological Survey, Report of, Vol. VIII. [Baltimore, 1909.]

—Mason and Dixon Line Resurvey Commission, Report on the Resurvey of
the Maryland-Pennsylvania Boundary Part of the Mason and Dixon
Line. [Maryland Geological Survey, Vol. VII, 1908.]

—MclInnes, Wm. Report on a Part of the North West Territories Drained
by the Winisk and Attawapiskat Rivers. [No. 1008, Canada Department
of Mines, Geological Survey Branch. Ottawa, 1910.|

—MEEK, S. E., AND HILDERBRAND,S.F. A Synoptic List of the Fishes Known
to Occur within Fifty Miles of Chicago. [Field Museum of Natural
History, Publication 142. Zodlogical Series, Vol. VII, No. 9. Chicago,
r910.]

—MitteEr, W. J. Trough Faulting in the Southern Adirondacks. [Science,
N.S., Vol. XXXII, No. 811, pp. 95-96. July 15, 1910.]

—Oscoop, W. H. Further New Mammals from British East Africa. [Field
Museum of Natural History, Publication 143. Zodlogical Series, Vol.
X, No. 3. Chicago, rgto.]

—Pernck, A. Das Alter des Menschengeschlechtes. [Aus der Zeitschrift
fiir Ethnologie. Heft 3. (1908).]

Die Weltkarten-Konferenz in London im November 1909. [Son-

derabdruck aus der Zeitschrift der Gesellschaft fiir Erdkunde zu Berlin.

1910. |

North America and Europe; a Geographical Comparison. [Science,
N.S., Vol. XXIX, No. 739, pp. 321-29. February 26, 1909.]

—PERKINS, G. H. Report of the State Geologist on the Mineral Industries
and Geology of Certain Areas of Vermont, 1909-10. [The P. H. Gobie
Press, Bellows Falls, Vt., 1910.]

—RUEDEMANN, RUDOLF. Cephalopoda of the Beekmantown and Chazy
Formations of the Champlain Basin. [Bulletin 90, Paleontology 14,
New York State Museum. Albany, 1906.]

—Scottish Geological Survey. The Geology of the Neighborhood of Edin-
burgh. (Edinburgh, ro1o0.]

—Sewarp, A.C. Fossil Plants, Vol. II. [Cambridge, 1o10.]

—SHREVE, F., Curysiter, M. A., BLopceEtt, F. H., anp Bestey, F.W. The
Plant Life of Maryland. [Maryland Weather Service Report, Vol. III.
Baltimore, 1910.|

—STEINMANN, G. Ueber die Stellung und das Alter des Hochstegenkalks.
[Mitteilungen der Geologischen Gesellschaft, Wien, III, roz10.]

—Utricu, E. O., anp Cusutnc, H. P. Age and Relations of the Little Falls
Dolomite (Calciferous) of the Mohawk Valley. [From New York State
Museum Bulletin 140, Sixth Report of the Director, 1909. Albany,
1910.|

—Western Australia Geological Survey. Paleontological Contributions to
the Geology of Western Australia. By Dr. Geo. J. Hinde, F.R.S., E. A.

672 RECENT PUBLICATIONS

Newell, Arber, M.A., F.L.S., F.G.S., R. Etheridge, Esq., Ludwig Glauert,
F.G.S. [Perth, roro.]
—Wuite,I.C. Levels, Coal Analyses. [Bulletin 2, West Virginia Geological
Survey. Morgantown, roto.|
—Witson, A. W. G. Geology of the Nipigon Basin, Ontario. [Memoir No.
1, Canada Department of Mines, Geological Survey Branch. Ottawa,
19I0.|
Report on a Traverse through the Southern Part of the North West
Territories from Lac Seul to Cat Lake in 1902. [No. 1006, Canada
Department of Mines, Geological Survey Branch. Ottawa, 1g1o.]
Wotcort, A. B. Notes on Some Cleridae of Middle and North America
with Descriptions of New Species. [Field Museum of Natural History,
Publication 144. Zodlogical Series, Vol. VII, No. 10. Chicago, 1910.]

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VOLUME XIX NUMBER 8

THE

JOURNAL or GEOLOGY

A SEMI-QUARTERLY

EDITED BY

THOMAS C. CHAMBERLIN AND ROLLIN D, SALISBURY
With the Active Collaboration of

SAMUEL W. WILLISTON ALBERT JOHANNSEN WILLIAM H. EMMONS
Vertebrate Paleontology Petrology Economic Geology

STUART WELLER WALLACE W, ATWOOD ROLLIN T. CHAMBERLIN
Invertebrate Paleontology Physiography Dynamic Geology

ASSOCIATE EDITORS

SIR ARCHIBALD GEIKIE, Great Britain GROVE K. GILBERT, National Survey, Washington, D.C.
HEINRICH ROSENBUSCH, Germany CHARLES D. WALCOTT, Smithsonian Institution
_ THEODOR N. TSCHERNYSCHEW, Russia HENRY S. WILLIAMS, Cornell University
CHARLES BARROIS, France é JOSEPH P.IDDINGS, Washington, D.C.
ALBRECHT PENCK, Germany ; JOHN C, BRANNER, Stanford University
HANS REUSCH, Norway RICHARD A. F. PENROSE, Jr., Philadelphia, Pa.
GERARD DEGEER, Sweden i WILLIAM B. CLARK, Johns Hopkins University
ORVILLE A. DERBY, Brazil : WILLIAM H. HOBBS, University of Michigan
T. W. EDGEWORTH DAVID, Australia FRANK D. ADAMS, McGill University
BAILEY WILLIS, Argentine Republic : \ CHARLES K, LEITH, University of Wisconsin
NOVEMBER-DECEMBER, 191
GONTEN TS
THE BEARINGS OF RADIOACTIVITY ON GEOLOGY - - - - - T. C. CHAmBERIIN 673

THE WING-FINGER OF PTERODACTYLS, WITH RESTORATION OF NYCTOSAURUS
S. W. WILLISTON 606

THE TERRESTRIAL DEPOSITS OF OWENS VALLEY, CALIFORNIA
ARTHUR C, TROWBRIDGE 706

ON CORUNDUM-SYENITE (URALOSE) FROM MONTANA- - - - Austin F. RocEers 748

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TION Sater seyias eth 2 ae ose A ee - Bio. 4s, © > > AUBERT, JOHANNSEN: 752
HEE AY SNS Si i) aaa cE a a iar ole iy AA eM i Coc eee 756

Che Anthbersity of Chicago press
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AGENTS:
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WILLIAM WESLEY & SON, Lonpon
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The Fournal of Geology

Published on or about the following dates; February 1, March 15, May 1, June 15,
August 1, September 15, November 1, December 15.

Vol. XIX CONTENTS FOR NOVEMBER-DECEMBER, 1911 No. 8

THE BEARINGS OF RADIOACTIVITY ON GEOLOGY- - - - - = = = T. C. CHAMBERLIN 673
THE WING-FINGER OF PTERODACTYLS, WITH RESTORATION OF NYCTOSAURUS S. W. WILLISTON 6096
THE TERRESTRIAL DEPOSITS OF OWENS VALLEY, CALIFORNIA - - - ArtHur C. TROWBRIDGE, 706
ON CORUNDUM-SYENITE (URALOSE) FROM MONTANA esis Oe NG es AUSTIN F. Rocers 748
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REVIEWS: come Sad Seis isp cho RI eee SiR ase eae eR A nea

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THE

ROURNAL OF GEOLOGY

NOVEMBER-DECEMBER, ror

THE BEARINGS OF RADIOACTIVITY ON GEOLOGY

T. C. CHAMBERLIN
University of Chicago

To the geologist the center of interest in the phenomena of
radioactivity lies in the spontaneous evolution of heat attending
atomic disintegration. This interest is the more piquant because
the source of the internal heat of the earth is one of the oldest of
its problems and the discovery of radioactivity brings into the
study an unexpected element. During the last century there
was a rather general consensus of opinion that the earth’s internal
heat was derived from the condensation of the nebula from which
the earth was then commonly supposed to have taken its origin.
This nebula was usually regarded either as a gaseous body or as
a quasi-gaseous meteoritic swarm, and in either case its condensa-
tion was thought to have given rise to intense heat. The primi-
tive gaseous or quasi-gaseous earth-mass was held to have passed
later into a molten globe, and the subsequent incrusting of this
to have entrapped in the interior the heat supply of subsequent
ages. This older view was still in general possession of the field
when the apparition of radioactivity forced a new line of thought.
But there was also an alternative view built on the belief that the
earth grew up gradually by the slow accession of discrete orbital
matter in distinction from the direct condensation of a gaseous
or quasi-gaseous mass. In this view, the internal heat arose
mainly from the self-compression of the earth-mass as it grew.
Vol. XIX, No. 8 | 673

674 T. C. CHAMBERLIN

This view had its origin in the grave cosmogonic difficulties that
had been discovered in the gaseous and quasi-gaseous theories
of the earth’s origin. Of the two rival views thus already in the field,
the one postulated a plethora of heat at the outset and a gradual
loss in all later time, the other postulated at the outset a more
limited supply of heat which was increased as compression pro-
gressed. The adequacy of such compression to give a sufficiency
of heat was a subject of debate from the inception of the view.!
To the interest that naturally attaches to the discovery of a wholly —
unexpected agency, already acute because of the agent’s singular
qualities, there was thus added piquancy in view of its inevitable
bearings on the thermal problem of the earth’s interior and on the
hypotheses of the earth’s origin.

An even more fundamental though less imminent interest was
awakened by the discovery that some of the atoms of the earth-
substance are undergoing spontaneous disintegration and that all
atoms may possibly be doing so and that even the permanency of
terrestrial substance may be brought into question. However,
matters of this ultra-radical nature cannot be discussed with
advantage as yet, for little light has been shed on the broad ques-
tion whether all terrestrial substance is in process of disintegration,
and on the complementary question whether atoms are some-
where and somehow undergoing integration.

If the general tenor of the studies thus far made is to be trusted,
nothing in the field of common experience seriously inhibits the
dissolution of the radioactive substances. It does not appear
that even the greatest heightening or lowering of temperature or
pressure that can be brought to bear either stays or hastens, in
any material measure, the progress of atomic disintegration. Nor
do any known changes of chemical union or disunion, of concen-
tration or diffusion, or of freedom or confinement seem materially
to retard or accelerate the spontaneous dissolution. There is
probably no warrant for an unqualified affirmation that neither
temperature, pressure, concentration, exposure, nor combination

t The status of the problem of the earth’s heat as it stood near the opening of the
twentieth century is sketched more fully in Year Book No. 2, Carnegie Institution,
1903, 262-65, and in Geology, Chamberlin and Salisbury, I (1904), 533-47.

BEARINGS OF RADIOACTIVITY ON GEOLOGY 675

affects the progress of radioactive decomposition, but no specific
effects of a critical value have been certainly disclosed by experi-
mentation. These conditions that so much qualify most geologic
_ processes must apparently be regarded as negligible for the present
so far as radioactivity in the earth’s crust is concerned. It is
thought by the leaders in radioactive science permissible to treat
radioactive substances as undergoing disintegration persistently
and uniformly under all known terrestrial conditions. In the
thermal problem of the earth radioactive particles may be dealt
with tentatively as centers of heat-generation whose efficiency and
endurance are conditioned simply by their atomic constitutions
and their mass values. In so far as these remarkable deductions
from experimentation may be thought to fall short of full warrant,
weakness in equal degree must of course be held to enter into the
geological inferences based on them; and in view of the radical
nature of the conclusions to which they lead, we cannot perhaps
too constantly bear in mind that the postulate of immunity to
conditions is the main basis of the geologic contributions credited
to radioactivity. But the remarkable verifications of skill and
accuracy that have followed the multiplication of tests furnish
an ample warrant for a serious discussion of present deductions.
There is strong presumption that future tests will further sub-
stantiate present conclusions so far as their main bearings on imme-
diate terrestrial problems are concerned, whatever interrogations
one may be disposed to indulge in regarding ulterior problems.

The clue to this extraordinary tenacity of radioactive disso-
lution in spite of conditions that profoundly influence most ter-
restrial processes, probably lies in the fact that the action springs
from the internal motions of the atomic constituents and that
these are of such intense nature and are actuated by such pro-
digious energies that the influences of ordinary chemical and
physical conditions are relatively insignificant.

At the same time, the radioactive substances show a decided
aptitude to enter into chemical combination under common con-
ditions. None of the parent radioactive metals is known to occur
in the earth in a native state. In the form of compounds they
have become widely distributed over the face of the globe in the

676 T. C. CHAMBERLIN

course of the surface changes it has undergone. Radioactive sub-
stances have freely entered into solution in the natural waters and
have thus been carried wherever the hydrosphere reaches, and in
turn they have been deposited therefrom. Their singular property
of passing spontaneously from certain states into gaseous forms
(emanations) and then back into the solid or liquid form, on defi-
nite time schedules, has caused them to be given forth freely into
the atmosphere, and, drifting in this, to be later precipitated in -
the solid or liquid form, and this has naturally been dispersive
in an extreme degree. Radioactive matter is therefore found in
practically all the rocks of the surface of the earth, in practically
all the waters, and in practically all the atmosphere.

But this highly diffusive distribution has not been uniform.
There have been special tendencies toward concentration running
hand in hand with the general tendencies to diffusion, and these
concentrative tendencies constitute a critical element in this dis-
cussion.

So far as the accessible part of the earth is concerned, the
igneous rocks may be taken as the original source of the radio-
active substances. How the igneous rocks themselves came to
have their present content will be considered later. Whence the
radioactive substances came still more remotely is problematical.
There may be even now accessions of radioactive substances from
without the earth for aught that is known, and indeed this is prob-
able; but, except in the form of meteorites whose content appears,
from the few tests made, to be relatively meager,’ such accessions
are not yet demonstrated.

The cycle of distribution on the earth’s surface is simple. From
the igneous rocks the radioactive substances are dissolved and
disseminated through the waters and carried wherever they go;
while from both the rocks and the waters the emanations are given
forth into the atmosphere. From the air and the waters in turn
the radioactive derivatives are reconcentrated into the earth,
except as their disintegration becomes complete and they pass
permanently, in the form of helium, into the atmosphere or are
lost from the atmosphere into the cosmic regions outside.

7 Strutt, Proc. Roy. Soc., LXXVII A, 480.

BEARINGS OF RADIOACTIVITY ON GEOLOGY 677

The special distribution of the radioactive substances among
the different kinds of igneous rocks is no doubt full of meaning,
but as yet the determinations have not been sufficient to justify
more than a few broad generalizations, and these must be held
subject to revision.* It may be said safely that the igneous rocks
carry a higher ratio of radioactive substance than the average
sediments. The reason for this is simple. The sediments are
derived from the igneous rocks, and in the process of derivation
some of the radioactive matter inevitably goes into the waters
and into the atmosphere, and this diversion leaves the content in
derivative rocks lower than that of the original rocks. If all the
radioactive matter that is lost into the waters and the air were
gathered into the derivative rocks, their content should equal
that of the igneous rocks from which they came, if no account be
taken of the loss by dissolution.

The earlier determinations of the amounts of radium in the
igneous rocks by Strutt seemed to show that the acidic class hold
more radioactive matter, on the average, than the basic class, and
a portion of the later determinations seem to support this generali-
zation, but the determinations of Eve and Joly, which have been
important, seem to bring the richness of the basic class into some-
what near equality with that of the acidic, and even to make the
preponderance of the one class over the other doubtful. The
point of special interest here lies in the inference that, if the lique-
faction and eruption of the igneous rocks is dependent on the heat
derived from radioactivity, the distribution of radioactive sub-.
stances in the erupted rocks should be inversely proportional to

t The larger number of determinations of radioactivity in rock have been made
by Strutt: Proc. Roy. Soc., LXXVI A (1905), 88 and 312; LXXXVII A (1906), 472;
LXXVIII (1906-7), 150; LXXX A (1907-8), 572; Eve: Phil. Mag., September,
1906, p. 189; February, 1907, p. 248; August, 1907, p. 231; October, 1908, p. 622;
Am. Jour. Sci., XXII, (December, 1906), 477; Bull. Roy. Soc. Con., June, 1907, pp. 3
and g; July, 1907, p. 196; Joly: Nature, January 24, 1907, p. 294; Phil. Mag., March
1908, p. 385; Radioactivity and Geology (1909), general treatment with references;
Elster and Geitel: Phys. Zeit., II (1900-1901), 590; III (1901), 76.

For the physics of radioactivity see J. J. Thomson: The Conduction of Electricity
through Gases; E. Rutherford: Radioactivity; (1904); Radioactive Transformations
(1906); F. Soddy: Radioactivity (1904); The Interpretation of Radium (1909); R. J.
Strutt: The Becquerel Rays and the Properties of Radium (1904); and the papers of
Boltwood, McCoy, and many others.

678 T. C. CHAMBERLIN

their temperatures of mutual solution or of fusion. But it must
be observed that even if such a casual distribution prevailed in
the rock-matter when first it took the liquid form, this distribution
might not persist indefinitely, for selective segregation has appar-
ently taken place during the later processes. It is quite clear
that the radioactivity is concentrated in some constituents rather
than others, as for example in zircon, pyromorphite, apatite, and
some other minerals, and in pegmatite and some other rocks.
The pegmatitic material, in segregating from a granitic magma,
seems to have gathered into itself an unusual proportion of the
radioactive substance of the parent mass. In the details of final
distribution, therefore, the different parts of the segregated rock-
material may rationally be expected to differ from one another
and from the parent magma in radioactive content. The deter-
minations thus far made, though not adequate to demonstrate
this, seem to be in consonance with it. Much interest will there-
fore gather about the forthcoming determinations as they multiply
and contribute their quota of evidence bearing on the radioactive
qualities of the various species of igneous rocks.

Among the derivative and sedimentary processes it seems clear
that there are modes of concentration also which have given to
different sediments different contents of radioactive substances.
It appears from the determinations already made that the radio-
active substances are leached out of the parent igneous rocks faster
than the average minerals of those rocks, for weathered igneous
rocks are found to carry less radioactive matter than fresh rocks.
This is in accord with the aptitude for chemical change already
noted; and yet soils which are almost the type of ultra-weathered
material still retain notable radioactivity, but a part of this is
probably a redeposit from the atmosphere. In general, it appears
that the clayey element carries more radioactive material than the
quartzose sands or the calcareous derivatives.

In the deep-sea deposits radioactive matter is higher than in
the deposits of the shallow parts of the ocean. In the red clays
and radiolarian oozes of the abysmal depths the content is markedly
greater than in the land-girting muds and sands, or the calcareous
oozes of mid-depths. This is assigned in part to the removal by

BEARINGS OF RADIOACTIVITY ON GEOLOGY 679

solution of the lime from the original matter of the abysmal deposits,
leaving them residual concentrates, and in part to the collection
in the depths, in relatively high proportions, of phosphate-bearing
relics (teeth, bones, etc.) with which radioactive substances are
associated. It is a suggestive fact that the phosphatic nodules
of the great deeps are highly radioactive compared with ordinary
sedimentary material. A part of this is clearly due to the con-
centration of the radioactive substances after the phosphates were
deposited, for fresh phosphatic material is notably less radioactive
than fossilized phosphates."

It appears then that the radioactive substances on the surface
of the earth are subject to special agencies that lead in part to
greater concentration and in part to wider distribution, and that
these act co-ordinately with the general dispersing agencies that
give radioactivity to the derivative rocks, to the waters, and to
the air.

If it were permissible to reason from what is known of surface
phenomena, particularly from the broad fact that radioactivity
increases as we go from air to water, from water to sediment, and
from sediment to igneous rock, it might be inferred very plausibly
that radioactivity would be found to reach its maximum concen-
tration in the heart of the earth, and certainly that the deeper
parts would be as rich as the superficial ones. This presumption
might very justly be felt to be strengthened by the fact that the
atoms of uranium, radium, and thorium are among the heaviest
known and that if the earth were ever gaseous or liquid, these —
heavy atoms might naturally be expected to be concentrated
toward its center unless the viscosity of the fluid mass were too
great to permit this, in which case the distribution should be either
equable or indifferent to depth.

But Strutt? early called attention to the fact that if such an
increasing abundance exists toward the center of the earth, or
if there were an equable distribution in depth, the heat gradient
as the earth is penetrated would be higher than observation
shows it to be. By computations on the data then available he

«Strutt, Proc. Roy. Soc., LX XX A, 582.

2 Proc. Roy. Soc., LXXVII A (1906), 472; LX XVIII A, 150.

680 T. C. CHAMBERLIN

concluded that a distribution of radioactive substance equal to
that of the surface rocks for a depth of only 45 miles would give
the rise of heat actually observed in wells, mines and other deep
excavations. Later data and closer scrutiny seem to confirm the
general soundness of Strutt’s inference, and to make the limita-
tions even more narrow. Joly, approaching the problem from the
geological as well as the physical point of view, and with the
advantage of later data, reached the conclusion that radioactivity
of the amount observed at the surface, if continued to a depth
ranging from 27 to 37 kilometers (17.2 to 23.5 miles), would give
rise to heat equal to that implied by the loss at the surface.t_ Accord-
ing to Joly, however, a complete concentration of radioactivity
in a shell of this depth does not meet the apparent requirements
of igneous phenomena if this be assigned to radioactivity. A
deeper distribution of a part of the radioactive matter and a less
concentration in the outer part of the crust is felt by Joly to be
required and he was led to this final statement: “If we said that
the richer part of the crust must be between 9 and 15 kilometers
deep, we cannot be far from the truth. This appears to be the
best we can do on our present knowledge.’ It is to be noted that
these deductions are reached on the supposition that all the internal
heat given out arises from radioactivity; no margin is left for any
original heat or for secular heat from any other source. On the
other hand, the computations seem to take no account of loss of
heat by means of igneous extrusions.

These remarkable deductions raise two questions of radical
import:

(1) If supplies of heat are generated currently by radioactivity
in such abundance that it is necessary to put these severe limits
on the distribution of radioactive substances, must we abandon
entirely all further consideration of supposed supplies handed down
from a white-hot earth or from any other form of the primitive
earth ?

(2) Is there among the internal processes previously postu-
lated any that provides a way in which such a concentration at

t Radioactivity and Geology (1909), 175.

2 [bid., 183.

BEARINGS OF RADIOACTIVITY ON GEOLOGY 681

the surface might naturally have taken place, or must we find a
new geological process to fit the new thermal difficulty ?

The rigor of the dilemma is softened somewhat by noting that
the deductions of Strutt, Joly, and their colleagues are based
simply on comparisons between the heat-generating power of
radioactive substances in the crust and the conductive power of
the crust. The functions of igneous extrusion as a mode of trans-
fer of internal heat do not seem to be taken into account. This
is not unnatural since the heat carried out by extrusive matter
and by waters heated by igneous intrusions has not usually been
regarded as an important factor in reducing the high temperature
inherited by the earth under the older view. But the movement
of igneous matter and of waters and gases heated by it has
been made to play an essential part in the working concepts that
have been based on the planetesimal hypothesis. There will be
occasion to return to this critical difference of view.

When the apparent excess of thermal riches arising from the
new source was first realized an escape from the dilemma raised
by it was sought in the natural supposition that the disintegration
of uranium and thorium was restrained by pressure in the depths
of the earth, and that, though present there, their activity was
greatly subdued or possibly inhibited altogether. This plausible
explanation was diligently tested; but the general tenor of experi-
ments on the effects of pressure, notably those of Eve and Adams'
in which the pressures were carried to intensities sufficient to cover
earth-pressures to the depths supposed to limit radioactivity and
beyond, showed no appreciable restraint on the disintegrating
process. It seems necessary, therefore, in the present state of
evidence, to accept the inference that the radioactive substances
are really concentrated toward the surface, and that the radio-
active content in the depths of the earth is of a much lower order.

It does not fall to me to adjust the new requirements to the
older view of the earth’s internal temperatures based on a molten
earth, for other considerations led me to the abandonment of this
view before the advent of the new issue. I must leave it to those
who hold to the molten hypothesis to battle with its new perils.

tNature, July, 1907, p. 260.

682 EC: CHAMBERELN,

With such a plethora of heat at the start as a molten earth implies
and with a new agency whose current production of heat would
seem to be excessively great if its prevalence were not construc-
tively minimized, it is not with regret that I feel absolved from the
task of finding a reconciliation between this venerable view and
the requirements of juvenile discoveries.

The discussion of Professor Joly,’ though not explicitly based
on the theory of a molten earth, is sympathetic with the general
tenets associated with such an earth, and his treatment may be
taken as offering the best approach to a reconciliation that seems
now possible.

It is interesting to note, however, that when Professor Joly
reached the critical question of a possible mode by which the
surface concentration of radioactivity could have come about
(Radioactivity and Geology, 184) he turned to the accretion or
planetesimal hypothesis. While he indicated the central line of
action on which the concentration might have been accomplished
he left without elucidation the line of reconciliation between the
heat gradient postulated by the planetesimal view and the
gradient he deduces from radioactivity.

It is the chief purpose of this paper to set forth what seems
to me to be the true harmony between the new light shed by radio-
activity and the tenets of the planetesimal view as shaped by
me before the discovery of radioactivity and to show the
co-ordination of the planetesimal and radioactive agencies in jointly
leading to the results observed. To this end it is necessary to sketch
with some care the thermal features of the planetesimal view in
the form to which preference was given from the start so that it
may be clear just what part radioactivity plays in the assigned
co-operation.

On the assumption that the earth grew up by the accession of
planetesimals, whatsoever heat arose from the condensation of the
nucleus about which the growth took place centered in the inner-
most parts and can affect present surface phenomena only by
transfer. The infalling matter that is supposed to have built up
the earth to its mature size must have generated much heat by

™ Radioactivity and Geology, 154-82.

BEARINGS OF RADIOACTIVITY ON GEOLOGY 683

its impacts, but as the infall is held to have been slow and as this
heat was superficial, it may be assumed that it was largely radiated
away before it became so deeply buried as to be permanently
retained, and so the most of the heat of impact may be regarded
as negligible.t In the original shaping of the planetesimal hypothe-
sis (before the discovery of radioactivity) the main source of inter-
nal heat was made to spring from the compression which the
deeper parts of the earth underwent by the increase of its mass as
the planet grew to maturity. This chief source was supposed to
be abetted by heat springing from the rearrangment and recom-
bination of molecules within the mass as time went on. Changes
in the distribution of the heat after it was developed were supposed
to follow by means of conduction and especially by the transfer
of hot fluid matter carrying latent heat.

It is important to the present discussion to note that the heat
generated by pressure did not affect the outer part and that it
-began to be sensible only when those depths were reached at which
the rocks suffered appreciable compression from the weight of the
rock-mass above them. Thus the heat gradient so generated
would rise only slowly in the outer part of the earth and faster
in a systematic way toward the center for a considerable depth,
if the compressibility of the rocks remained uniform to indefinite
depths. If the compressibility fell off as compactness increased
the rate of thermal rise toward the center would have been slower.
Compressibility at the surface seems to be nearly proportional to
pressure, but the compressibility of rocks after they have been
compacted by such pressures as are attained at considerable depths
is unknown, and it is necessary to proceed here by alternative
hypotheses. The extrapolation of the curve found under experi-
mental pressures is of course entitled to precedence and this alter-
native was used as the basis of the first approximation to the heat
curve of the earth’s interior. For the other factors, such as specific
heat, necessarily taken into account in the computation, assump-
tions as near to known facts as possible were made. On these
assumptions it was found that the heat generated between the
surface and the center of the earth may be represented by a curve

t Chamberlin and Salisbury, Geology, I, 533.

684 T. C. CHAMBERLIN

which rises at a very low rate near the surface and is followed by
a slowly increasing rate for about one-third the distance to the
center, beyond which it rises at a decreasing rate to the center;
or, if traced from the center outward, this computed curve of
temperature declines faster and faster at every step for about two-
thirds of the distance and then declines less and less rapidly to a
vanishing-point near the surface. Hence if conductivity be
assumed to be the same at all depths, the outward flow of heat on
such a gradient would increase in rate from the center to the two-
thirds point and then grow slower toward the surface, from which
it follows that, on these assumptions of uniform compressibility
and uniform conductivity taken by themselves, the internal heat
should have been progressively lowered in the deep interior and
raised in the more superficial parts. The conductivity of rocks is
so very slow, however, that its effects at the surface under the con-
ditions named cannot have been large up to the present unless
the earth is much older than even radioactivity seems to imply.

This first approximation to a theoretical curve of heat, even
when modified by conduction, has not been supposed to represent
the actual distribution of heat at the present time, for reasons that
follow.

There is ground to think that compressibility falls off as
increased degrees of compactness are attained. In working out
the curve which was published in Geology, I, 566 (Chamberlin
and Salisbury), Dr. Lunn used as a guide the Laplacian law of
density which postulates that density varies as the square root
of the pressure. This distribution of density harmonizes fairly
well with such astronomical tests as are available and gives a mean
density for the earth which is near that required by the earth’s
total weight. The assumption that the increased density of the
interior is all due to compression, however, makes no allowance
for the probable transfer of lighter matter to or toward the sur-
face by extrusive action which would tend to increase the mean
specific gravity of the residue. The curve of Dr. Lunn may be
regarded as a second approximation. But this, as noted, does

« Year Book No. 3, Carnegie Institution of Washington, 1904, p. 156; also ‘‘Geo-
physical Theory under the Planetesimal Hypothesis,” Section II of “Tidal and Other

BEARINGS OF RADIOACTIVITY ON GEOLOGY 685

not take into consideratiion the effects of liquefaction and extru-
sion and these in the planetesimal view are of the first order of
importance. The theoretical curve mathematically deduced by
Dr. Lunn is, however, an indispensable basis for a third approxi-
mation in which the effects of liquefaction and extrusion are taken
into account.

Before passing on to consider liquefaction and extrusion, it is
well to note that the Lunn curve based on the Laplacian law of
density also is low near the surface and that its rate of rise is much
below that of the temperature gradient observed in wells and
mines. Dr. Lunn, on assumptions carefully specified in his dis-
cussion in the paper cited, found the rise in the first 200 miles
only; 3307.C.

This low development of heat in the outer part of the earth
seemed at first thought to present a difficulty of a rather serious
nature, but it was believed to be met by the effects of liquefaction
and extrusion, and these were made the chief basis of an additional
approximation to the actual temperature curve (Chamberlin and
Salisbury, Geology, I, 265-67). It was held that the rising heat
of the interior would reach the temperatures of fusion or of mutual
solution of some ingredients in the mixed material much earlier
than that of other ingredients, and that the ascent of the portion
that became molten carrying its latent as well as sensible heat
into the cooler outer zone would necessarily raise the temperature
of that zone. It was held that the continuation of this process
served as a constant influence tending to retard the rise of tem-
perature in the deeper zone where the partial liquefaction was in
progress while it progressively raised that of the outer zone into
which the liquid rock was intruded, whether it lodged in the crust
or passed through it to the surface. This extrusive process was
supposed to have continued to the present day and to have resulted
in a permanent adjustable working curve of accommodation
between thermal, fluidal, and mechanical conditions. ‘This curve,
except in the cool crust, was essentially identical with the fusion-

Problems,” Publication No. 107, Carnegie Institution of Washington, 1909, pp. 169-
231; for a summary and figure of curve see also Chamberlin and Salisbury, Geology

(1904), I, 566.

686 T. C. CHAMBERLIN

solution curve, whatever that might happen to have been for the
time being under the local conditions of pressure, state of strain,
nature of material, means of escape, and other properties that
affected liquefaction and extrusion. It was regarded as essen-
tially a curve of equilibrium between solidity and liquefaction accom-
modated to the conditions present at each depth and at each stage _
and was maintained automatically. The actual curve as thus
assigned continued always to be essentially the liquefaction curve
after that was once attained. The view excludes automatically
all internal temperatures higher than the local liquefaction tem-
peratures and of course excludes all pervasive gaseous conditions
except that of the interspersed and occluded gases of the mixed
mass. ‘These interspersed gases assisted extrusion and hence
were among the parts most freely extruded. All theoretical
inferences based on temperatures higher than the temperatures of
liquefaction are excluded from consideration under this view by
its very terms.

Certain structural conditions postulated by the planetesimal
hypothesis greatly favored this automatic action. The infalling
matter was assumed to have built itself up in a very heterogeneous
manner with the result that the mass of the earth was an intimate
mixture of all the kinds of material that made up the spiral nebula
from which it was supposed to have been gathered. As this mixed
matter was heated by compression, some parts of it must certainly
have reached temperatures at which they could go into mutual
solution or into fusion while as yet other closely associated parts
had not reached temperatures that permitted such action, and as
the rise of temperature was very slow by the terms of the hypothe-
sis the passage of successive parts into liquefaction was widely
separated in time. Fluid parts thus came temporarily to be inti-
mately mixed with solid parts. These fluid parts, in the act of
passing into solution or fusion, absorbed the necessary energy of
liquefaction at the expense of the increasing supply. On their
ascent into the crust they heated it. If they lodged there and
resolidified they gave up their heat of liquefaction. If they
reached the surface the residue of heat, both sensible and latent,
was lost. By such liquefaction and transfer these portions served

OPA Ci nS OMe

BEARINGS OF RADIOACTIVITY ON GEOLOGY 687

to protect the residue in the deeper parts from liquefaction for
the time being and the continuation of the process extended the
protection to such residue as continued to persist.

It is not necessary to offer evidence that ascent of liquid rock
took place in great quantities in the early geologic ages and has
been more or less active in all ages down to the present. One
of the extraordinary facts of the Archaean terranes is the extensive
lodgment of liquid rock in the crust, and even in later ages batho-
litic phenomena have attained surprising magnitudes. The
extrusion of molten rock at the surface was a very pronounced
phenomenon as late as the Tertiary and is still an active process.
As this extrusive action was widely distributed over the surface
at various altitudes and at various stages through great lapses of
time and yet was never really very massive when measured in
terms of earth-volumes at any one time or place, it is of critical
value here to note that the view built on the planetesimal hypothe-
sis appeals to a special set of conditions of liquefaction and extru-
sion which are peculiarly favorable for selective work in small
masses and unfavorable for general liquefaction. In this respect
the conditions it assigns stand somewhat in contrast with the
conditions usually assumed to be the natural inheritances from a
general molten condition. The inference that general liquefaction
would take place on any general rise of heat is natural enough in
a case in which the whole mass has been solidified from a previous
molten state, for such a mass might be presumed to return mass-
ively into its former state on a reversal of conditions; but the
heterogeneous condition of the mixed matter of the interior postu-
lated by the planetesimal view is not favorable to a simultaneous
fusion of the whole mass or any large continuous part of it unless
extrusion be restrained until a high temperature is attained. Such
restraint is here held to be dynamically inconsistent with the
mechanism and the stress conditions of the earth-body. In addi-
tion, therefore, to such a mixed state of material in the interior as
_ peculiarly to invite selective liquefaction as the temperature
slowly rose, the planetesimal view postulates a set of stress agencies
that worked co-operatively to effect extrusion as fast as liquid
matter accumulated in workable volume.

688 T. C. CHAMBERLIN

In considering stress effects, it is necessary scrupulously to
distinguish between hydrostatic stresses which operate equally on
all sides of a given unit and so only produce compressive and like
effects, and differential stresses which promote movement and
change of form. ‘The effect of differential stresses on the solid
parts of the earth is primarily to produce strains; the effect on
liquid parts is primarily to produce flow and relocalization. And
so by reason of this difference of effect, a general differential
stress on any large part of the earth is apt to become locally sub-
differentiated when solid and liquid parts are intermixed, especially
if the liquid and solid states of these parts are partially inter-
changeable because their temperatures lie so close to the line of
equilibrium between solidity and liquidity. Tensional strains
promote liquefaction in bodies constituted as most rocks are;
compressive strains resist liquefaction in such bodies. And so
general differential strains co-operate with temperature in pro-
moting or in restraining the passage of matter from the one state
to the other according to the nature of the strain and thus have
some influence in directing and facilitating movement as well as
in forcing it.

Some of the differential stresses in the earth are essentially
fixed and constant, such as the direct pressures that arise from the
action of gravity. These stresses range from one atmosphere
at the surface to about three million atmospheres at the center.
Such pressures tend to force lighter bodies toward the surface while
heavier bodies seek the center in ways so familiar that we need
not dwell on them, nor on the fact that, since molten rock is usually
lighter than the same rock in a solid state, this static differential
stress of gravity presents a general condition that favors the
ascent of liquid rock. So also the incorporation or generation of
gases in liquid rocks tends to lessen the specific gravity and increase
the mobility and hence the gaseous element adds another general
influence that favors ascent.

In addition to these very general and persistent stresses, more
special differential stresses have arisen at various times from
inequalities of accession, from transfers of matter, from loss of
heat, and from other varying agencies, and these have been present,

BEARINGS OF RADIOACTIVITY ON GEOLOGY 689

in one form or another, at nearly all times in the earth’s history.
They have often been cumulative until they reached diastrophic
intensity and manifested themselves in impressive deformations.
That these have been effective agencies in forcing the movement
of liquid parts within the earth in the lines of least resistance and
of best accommodation to existent conditions is scarcely debatable.

In addition to the simple stresses of gravity and to the dia-
strophic stresses, there have been superposed at all times a series
of stresses of a rhythmical pulsatory nature acting throughout the
body of the earth. The nature and function of these has not
been so generally recognized. ‘These stresses are derived from the
differential action of the gravity of neighboring bodies, particularly
that of the moon and of the sun. ‘Tidal and tidelike stresses and
strains have swept through the earth’s body in a constant cycle
bringing to bear on each part a perpetual succession of compres-
sive and tensional stresses and strains alternating with one another.
The effect may be pictured as that of a minute kneading of the
earth-body. There is not only a superposition of pulsating strains
on the more static strains but a superposition of pulsating strains
on pulsating strains. The pulses of the twelve-hour body tides
are overrun by tides of longer periods and these are attended by
shifts of direction of strain, all of which tend to knead the mixed
matter to and fro and promote insinuation of the liquid parts
along the lines of escape.

Underlying all these rhythmical strains there has been ever
present a variation in intensity from center to surface. Sir George
Darwin has shown that the tidal stresses generated by the moon at
the earth’s center are eight times as great as those at its surface.
Each compressive strain squeezes the lower part of each liquid
vesicle or thread more than the upper part.

The coexistence of these pulsatory and periodic strains with
the simple static stresses of gravity and the less constant dias-
trophic stresses sufficiently imples their co-operative nature.
All these three classes are either differential stresses or have
factors or phases that are differential, and so, in specific local appli-
cation, they are all transformed into sub-differentiational effects
on the liquid and solid parts.

690 T. C. CHAMBERLIN

Under the planetesimal view the joint effect of these differ-
ential stresses and their resulting strains has been at all times
to force toward the surface liquefied rock as fast as it gained work-
able volume. Much aid in insinuating itself along liquid lines
and in fluxing a more open path until the fracture zone was reached,
is assigned to the mixed nature of the material and. to the local
strains imposed by the stress agencies. The whole picture centers
on the fundamental dynamic proposition that energy in mobile and
expansive embodiments seeks the surface, while its fixed embodiments
are forced more firmly together toward the center.

The extrusion is held to have begun as soon as the susceptible
matter took the mobile form. Possible exception is admitted in
the case of matter that may have been too dense to be forced to the
surface. However, a high density of small masses enmeshed in
masses of less density could only contribute to an average effect
so long as a high state of viscosity was retained, and a rela-
tively high viscosity for the small mobile masses, naturally arose
from the close balance between the liquid and solid states. Such
a condition seems equally to be implied by the remarkable mixtures
of dense and light matter often seen in the igneous rocks.'

The matter forced early to the surface is held to have been
buried by further accretions to the growing planet, later to have
been subject to a second liquefaction and extrusion, a second
burial, and so on. Progressive selection and reselection are postu-
lated until the growth essentially ceased. Since then a more
complete selection and concentration of the eutectic material at
the surface has been in progress as far as further generation of
internal heat has furnished the actuating agency.

Now if this picture in its working details and in its rather sharp
antithesis to the older view is clearly in mind, the part which the
radioactive substances may be supposed to play in co-operation
with this mechanism without changing the general conception
is little less than self-evident. The radioactive particles are
sources of self-generated heat. Under the planetesimal view the
radioactive substances were promiscuously scattered through the
mixed mass as it was gathered in heterogeneously from the nebula

* Chamberlin and Salisbury, Geology, II, 121-22.

BEARINGS OF RADIOACTIVITY ON GEOLOGY 691

by the crossing of the planetesimal orbits. No original segrega-
tion of this class of matter more than of any other heavy material
is assignable. The relative amount of the radioactive matter, at
least of the classes now known to be radioactive, must have been
extremely small and its influence on the specific gravity of the
matter with which it was mixed must have been negligible. The
self-heating effects of these disseminated particles were necessarily
expended first upon themselves and next upon adjacent matter,
and, other things being equal, this homemade heat should have
given these parts precedence in passing into the mobile state.
Normally the mixed units that inclosed a radioactive particle
should have been as susceptible of partially passing into the liquid
state as similar units that were free from radioactive matter.
The special source of heat should have turned the balance in favor
of the unit immediately surrounding the radioactive particle.
Thus the radioactive matter normally became involved in the
mobile matter and passed with it to or toward the surface.

With every stage in the growth of the earth and with every
reburial of the radioactive material a second similar preferential
action should have followed. On the essential completion of the
growth of the earth a more complete concentration of the self-
heating matter should have followed, for additional weighting by
accretion had essentially ceased and compression had become
essentially static while the self-heating competency of the radio-
active matter, though no doubt somewhat reduced by consump-
tion, was probably more efficient relatively in the production of
heat than it had been during the more active stages of growth.

It seems clear, therefore, that at all times after the volcanic
process was well under way radioactivity should have been rela-
tively most active in the outer part of the earth and should have
become especially so in the latest stages of the earth. It is there-
fore not too much, perhaps, to claim that a specific basis in favor-
able conditions and a definite working mechanism for an effective
concentration of self-liquefying matter at the surface was postu-
lated in a singularly apt way before radioactivity was discovered,
and quite irrespective of the dilemma which its discovery has
involved.

692 T. C. CHAMBERLIN

Reciprocally radioactivity greatly eases the burden laid on ©
compression in the outer part of the earth where it is least compe-
tent and where resort was had to igneous intrusions from below to
give the crust its observed temperatures. With the addition of
the new thermal agency the extrusions are presumed to play much
the same part as before but more actively, as they must now be
supposed to meet the liquefying effects both of compression and
of radioactivity. If there was ground before to question the
efficiency of compressional heat, aided by such other sources as
were formerly assignable, to give rise to the high degree of igneous
activity that marked the Archaean ages and to sustain the lesser
igneous action of later periods down to the present, this doubt is
amply resolved by the combined efficiency of compression and
radioactivity. In any case it is certain that a large amount of
energy has been brought to the surface and radiated into space.

Radioactivity also comes to the aid of other agencies of extru-
sion in the peculiar service it renders in opening a path for the
outward movement of the liquid matter. In the liquefying pro-
cess, as we have seen, the radioactive particles should have been
gathered by their self-heating action into the liquid vesicles and
have been forced outward with them. The self-heating property
thus became an endowment of the liquid and gave to it thermal
efficiency in dissolving and fluxing its way. This efficiency was
continually renewed by the progressive disintegration of the radio-
active atoms. It is not improbable that the liquid threads were
thus aided in a very special way in boring upward, for it seems
obvious that the part of the liquid which carried most of the self-
heating constituent would come to have the highest temperature,
the lowest specific gravity, and the largest gaseous factor—for
the disintegration produced gas emanation and helium in addition
to the gases generated by the heat alone—and hence would take
the uppermost position and bring its liquefying influences to bear
on the solid matter which lay between it and the surface toward
which it was pressed. The very mechanism may thus have kept
the most effective part at the point most critical to its ascent.

While this outline falls far short of an adequate discussion of
the relations of radioactivity to the planetesimal hypothesis, it

BEARINGS OF RADIOACTIVITY ON GEOLOGY 693

will perhaps suffice to point out the line of co-operation of the new
thermal agency with the new genetic hypothesis. The two seem
to co-operate happily. Jointly they seem to furnish a promising
basis for a revised thermal geology in harmony with accumulating
geologic data in various lines and with the growing evidence of the
elastic rigidity of the earth-body as a whole. At least the con-
centration of the radioactive substances at the surface seems to
be aptly explained, and the mechanism that conserves the solidity
of the earth falls into consonance with the new experimental evi-
dence of an elastico-rigid body-tide which seems scarcely less than
decisive.

There is perhaps one further point, among the many remaining,
that should be briefly touched here lest there seem to be an out-
standing incongruity in the present distribution of vulcanism. If
there is a progressive supply of heat in the earth’s crust springing
from radioactivity and if it is this that actuates vulcanism, why
are not volcanoes more uniformly distributed over the face of the
globe? A general sub-uniform distribution is a natural deduction
from the postulates. The distribution of pits on the moon, assum-
ing that they are volcanic craters, fairly fits the picture that nor-
mally arises from the action of such an agency. Especially is this
true if vulcanism is effected in so selective and so individual a way
as we have indicated. Why has not such a distribution persisted
on the earth? It will perhaps be conceded that the prevalence
of vulcanism in Archaean times fairly satisfies the terms of the case.
But at present volcanoes are rare in the primitive shields that form
the nuclei of the continents while volcanoes are concentrated about
the borders of the continents and in the deep basins and are par-
ticularly abundant where the great segments of the crust join one
another. The primitive shields are indeed intimately scarred and
shotted with igneous intrusions of the early ages, but they are
almost immune now.

There seem to be two lines of plausible explanation. These
old embossments have suffered denudation from an early date
and the matter removed has been carried to the borders of the
adjacent basins. According to the hypothesis of concentration
at the surface, this lost matter carried a relatively high proportion

604 T. C. CHAMBERLIN

of radioactive substance. When this was in the state of a mechani-
cal sediment it was chiefly deposited on the borders of the basins;
when it was in solution it mixed with the waters of the oceans and
was later largely concentrated in the oceanic precipitates. Thus
the prolonged process of denudation cut away the radioactively
richer part of the shield and added it to the undenuded crust of
the continental borders and the oceanic basins, thinning the one
and thickening the other in a special radioactive sense. Besides
this the lower crust in the denuded area was lifted relatively toward
the cold surface, while in the depositional area it was relatively
depressed beneath a growing radioactive mantle.

The rise of the denuded embossments of the crust was attended
by elastic expansion of the whole sector of the earth beneath, since
the gravitative pressure was lessened throughout. A lowering
of the melting-points indeed attended this and doubtless a change
also of the mutual-solution conditions, but this was anticipated
by the elastic expansion and its instantaneous cooling effects, a
point usually overlooked.

In addition to this immediate expansional effect, it is held by
some geologists, with whom I am glad to associate myself, that
the protruding portions of the continents tend to lateral creep and
that this carries with it tensional effects as well as some further
elastic expansion. At the same time, the penetration of surface-
water is promoted and this aids effectively in carrying off the heat
of the outer crust. It may be observed that while meteoric cir-
culation penetrates to considerable depths beneath land surfaces
there is little reason to think that there is any effective circulation
to appreciable depths in the ocean beds.

One further agency is believed to co-operate with these at a
lower horizon but this can be touched only with reserve as it
involves joint studies yet in progress upon which I do not feel at
liberty to draw further than may be necessary merely to indicate

their bearing on this particular problem.’ In a previous part of

« The studies are common to my son, Rollin T. Chamberlin, and myself and in
the particular here applicable the junior partner is the leader in pursuance of lines of
inquiry growing out of his studies on “‘ The Appalachian Folds of Central Pennsylvania,”
Journal of Geology, XVIII, No. 3 (April-May, 1910).

BEARINGS OF RADIOACTIVITY ON GEOLOGY 695

this paper the selective influence of strains on fusion and solution
was cited. There seems little doubt that a similar influence is
exerted by the great zones of strain that are developed in the earth
by diastrophic agencies. Among the tentative distributions of
these under study, a specific system seems more probable than
others and this is of such a nature as to direct fluid matter, par-
ticularly any that may arise at considerable depths, toward the
lines that are affected by volcanic extrusions.

THE WING-FINGER OF PTERODACTYLS, WITH RES-
TORATION OF NYCTOSAURUS

S. W. WILLISTON
The University of Chicago

The question whether the wing-finger of pterodactyls is the
fourth or the fifth has been disputed for the past eighty years,
though for the past forty years authors have been almost unani-
mously agreed that it is the fifth. The first writer of credibility
who expressed an opinion on the subject was Cuvier, who con-
sidered it the fourth. His reasons for so doing, as published in his
Ossemens Fossiles, are today, I believe, unanswerable, and to him
should be given the credit, and not to H. v. Meyer, for the correct
recognition of the finger. I quote his remarks in full:

En fin il a ce doigt énormément prolongé en tige gréle, qui caractérise
éminement notre animal.

Il a quatre articulations sans ongle. Le quatriéme doigt des lézards aurait
cing articles et un ongle; mais, dans les crocodiles, il n’a que quatre articles, et
il est dépourvu d’ongle comme ici; seulement il n’y éprouve pas ce prolonge-
ment extraordinaire.

Le crocodile et les lézards ont en outre un cinquiéme doigt qui dans les,
lézards a quatre articles, et dans le crocodile est réduit a trois sans ongle.

Il parait que dans l’animal fossile il ne reste qu’un vestige de cinquiéme
doigt, mais assez obscur et sujet 4 contestation.

Le grand doigt est probablement le quatriéme, car c’est aussi le quatriéme
qui est le plus long dans les lézards.

Les trois autres le précédaient dans l’ordre inverse du nombre de leurs
articles.

The first author to adopt the other view, that the finger is in
reality the fifth, was Goldfuss, who, as Plieninger has shown in his
full and reliable review of the subject, thought he saw in the pteroid
bone a first finger, accidentally misplaced in his specimen, and
in which he thought he recognized an additional phalange even.
H. v. Meyer early adopted Goldfuss’ view, as shown in the following
quotation: ‘“‘Es zeichnen sich diese Thiere vor allen anderen
wirklich dadurch aus, dass der Finger sie zum Fliegen befahigte,

696

THE WING-FINGER OF PTERODACTYLS

und zwar nur ein Finger, die Ohr-
finger, welche wegen der Kleinheit
womit er in der Hand anderen
Geschdpfe sich darstellt auch der
kleine Finger genannt wird” (Pale-
ontographica [1851], 19).

But Meyer soon returned to the
Cuvierian position, calling the first
of the small, clawed fingers the
thumb. I can find no independent
arguments of Meyer giving the
reasons for his views; indeed in
various places he is more or less
obscure, referring to the ‘Flug-
finger’ as the “Ohrfinger,” though
there can be no doubt but that as
early as 1860 he had, as I think,
correctly recognized the digit as
the fourth. Owen in his Pale-
ontology and Comparative Anatomy
of Vertebrates figures four small,
clawed fingers in front of the wing-
finger, which he calls the fifth.
Later he reverted to the Cuvierian
view. Goldfuss’s views were fol-
lowed by Oscar Fraas and most
modern authors, including Marsh,
Zittel, Plieninger, and Eaton. In
1904," without at the time having
read Cuvier’s remarks on the sub-
ject, I published a brief article in
the London Geological Magazine
giving reasons for the older view,
that the finger is in reality the
fourth, as based chiefly upon the
recognized normal number of
phalanges in the hands of reptiles.

“The Fingers of Pterodactyls,” The Geological Magazine, 1904, p. 59.

697

Fic. 1.—Restoration of Nyctosaurus gracilis Marsh, by Herrick E. Wilson

698 S. W. WILLISTON

Two years later Plieninger’ discussed the subject fully and well,
reaching no positive conclusion, though evidently favoring the
Goldfuss view that the finger is the fifth. He showed that Goldfuss,
and not Fraas, as I had thought, was the first author to suggest the
identification of the pteroid with the first finger, and corrected
Seeley’s statement that Meyer had so recognized it. We have seen
from the quotation that Seeley was really not so far wrong after
all, since Meyer did at one time consider the ‘“ Flugfinger” as the
“Ohrfinger.” Finally Abel? in a recent paper has restated the
problem, adopting the original Cuvierian view.

As bearing upon this question we have been fortunate in recent
years in determining the intimate structure of the hands and feet
of several of the early reptiles, from which I may say with entire
assurance that, until the close of Carboniferous times, and prob-
ably till the close of Permian times, the phalangeal formula for
reptiles was the primitive one of 2, 3, 4, 5, 3 for the front feet;
2, 3, 4, 5, 4 for the hind. Plieninger has raised a question in the
cited paper whether the formula 2, 3, 4, 4, 3, aS seen in the
crocodiles, was not really the primitive one for the hands instead
of 2, 3, 4, 5, 3, as found in the generality of modern lizards and in
Sphenodon. In the accompanying figures the front limbs of three
of these reptiles, from the so-called Permian of Texas and New
Mexico, are shown, made out with certainty in nearly every detail.
In Fig. 4 the distal three phalanges of the fourth finger have not yet
been positively fixed, but inasmuch as the fourth digit of the hind
foot of the skeleton to which the figured hand pertains has definitely
five phalanges, there can be no doubt of the number in the same digit
of the hand. In Figs. 2 and 4 the bones of the forearm and wrist are
shown in a horizontal plane without the foreshortening of the
oblique position that they really had in life, and which is shown in
Fig. 3. Fig. 2 is that of a cotylosaur, probably belonging in the

suborder Pareiasauria, while Figs. 3 and 4, Ophiacodon’ and Vara-

1 “Ueber die Hand der Pterosaurier,”’ Centralbl. fiir Mineralogie, Geol., etc., 1906, p
399; also Paleontographica, LIII (1907), 301.

2“T)ie Vorfahren der Vogel,’ Verhandl. der K.K. zoologisch-bot. Gesellsch., LXI
(1911), 163.

3 The full description of this genus will appear shortly in a paper by Dr. Case and
the writer.

THE WING-FINGER OF PTERODACTYLS 699

nosaurus, are zygocrotaphic reptiles that may be included in the
order Theromorpha or Pelycosauria.

Fic. 2.—Right front leg of Limnoscelis Williston, a cotylosaur reptile from the
Permian of New Mexico. A little less than one-half natural size.

700 S. W. WILLISTON

In all these forms it will be observed that the fifth digit is much
reduced, more so than in the hind feet of the same animals. The
number of phalanges in this finger in each is three and no more; this
is positive. Furthermore it will also be observed that the support-
ing carpale 5 is reduced or wanting in all; that is, the loss of this .
bone, the rule in all later reptiles, had begun even before the close
of Carboniferous times."

It may therefore be assumed with assurance that the ancestors
of the pterosaurs had the phalangeal formula for the hand of 2, 3,
4, 5, 3, with the fifth finger much reduced in size and its supporting
carpale 5 greatly reduced or entirely lost. In adaptation to aerial
flight the pectoral girdle? and front limbs in the pterodactyls have ~
been greatly modified throughout. In Pleranodon and Nyctosaurus,
the most highly specialized, but three carpal bones remain, a
proximal one, doubtless the fused radiale, intermedium, and ulnare;
a lateral carpal for the support of the pteroid, which may be either
the centrale or the first carpale; and a distal one, which in my
opinion represents the fourth carpale alone; which, it will be seen,
is the largest in reptiles. The carpale bearing the “ Flugfinger”’ is
always the larger; in Pterodactylus there is another, smaller one
in front bearing the anterior metacarpals. I cannot believe that
this carpale is the reduced or lost fifth carpale of the ancestral
pterosaur carpus, nor that the wing-finger has migrated from its
own vestigial carpale to the enlarged fourth while the fourth has
migrated to a more anterior carpale. From the carpus then of
pterodactyls it would seem highly probable that the carpale is the
fourth and that it supports its proper finger the fourth, and not
the fifth.

As has been known since the time of Cuvier, the phalangeal
formula in pterodactyls, beginning with the first clawed finger, is

tT may mention here that evidence is accumulating to prove that the so-called
Permian of Texas, or at least its lower part, and of New Mexico, as well as of Illinois,
really pertains to the upper part of the Pennsylvanian.

2In my recent work on American Permian Vertebrates, p. 58, fourth line from
bottom, occurs an unfortunate error, due to the omission of a qualifying phrase,
“absent ‘among nonamphibious reptiles,’’? whereby I say that the supracoracoid
foramen is wanting only among Pterosauria, when its absence in the Plesiosauria, most
Ichthyosauria, Phytosauria, Chelonia is known to all.

THE WING-FINGER OF PTERODACTYLS 701

2, 3, 4, 4, to which there are probably few or no exceptions. The
first three of these agree absolutely with the normal and primitive
formula of the first three digits. The fourth pterodactyl finger has

Sar,
SSS

Fic. 3.—Right front leg of Opkiacodon Marsh, a theromorph reptile from the
Permian of New Mexico. Two-thirds natural size.

702 S. W. WILLISTON

but four phalanges, one less than the normal number, and quite
that of the crocodiles; that is, as I have previously urged, it lacks
the claw. In the acquirement of a membrane-bearing function this
is precisely what would be expected in any finger, and is what
occurs in the bats, as Abel has said. That the claw gradually
elongated, changing its function from prehension to supporting,
seems highly improbable. This finger then answers all the require-
ments for the fourth. If, on the other hand,.in consonance with the
Goldfuss theory, it is the fifth digit which acquired the membrane-
supporting function, not only must the claw have changed its
function and become elongated but a new phalange must have been
added to the finger. Although among aquatic reptiles hyper-
phalangy is a common characteristic, we know of no instance among
terrestrial vertebrates that I can recall where an additional phalange
has been acquired, in either the front or the hind feet. And, if the
Goldfuss theory be true, not only must there have been hyper-
phalangy in the fifth digit, but hypophalangy in the four preceding
digits; that is, in the acquirement of a wing function, an increase
and loss of phalanges must have occurred concurrently in the hand.
I cannot believe that this was the case. Had we not to deal with
the peculiar bone called the pteroid, articulating with the carpus
and turned backward toward the elbow, the question of the homol-
ogy of the wing-finger would doubtless never have been raised.
It is the pteroid, then, which has caused all the dispute, from the
necessity of accounting for the bone, which, other than a misplaced
first metacarpal, seems inexplicable. ‘Two derivations have been
imputed to it, as a sinew bone, and as a sesamoid bone. In favor
of its being merely an ossified sinew is the fact that, in the remark-
able specimen I have described of Nyctosaurus, seven well-ossified
tendon bones are seen lying by the side of the forearm and hand,
elongated bones with one end flattened and the other attenuated.
In favor of the latter view that it is merely a sesamoid bone
developed in the tendon of some carpal muscle originally is the fact
that sesamoid bones do occur elsewhere in the pterodactyls. In the
above-mentioned specimen of NVyctosaurus I found one lying over
the end of the radius and another over the outer end of the coracoid;
and I have seen them often in Pleranodon. Sesamoid bones have

THE WING-FINGER OF PTERODACTYLS’

bursal sacks and synovial joints.
as a tendon or sesamoid bone is
quite possible and even probable,
but that the bone finally acquired
another function, at least in the
most highly developed forms,
would seem to be very prob-
able. The function that has
generally been ascribed to it is
that of a “Spannknochen”’ or
tensor of the patagial membrane
in front of the elbow. Under
the assumed relations of the
membrane to the front of the
arm I have protested against this
theory, since the fact is that

there could have been little or

no membrane in this region to
be rendered tense, provided the
membrane terminated, as is
usually assumed, at the shoulder.
Under the assumption that it
really served as a “Spann-
knochen”’ I have suggested in
an earlier paper that the mem-
brane continued beyond the
shoulder along the side of the
neck to the skull.

In the accompanying restora-
tion, Mr. Herrick E. Wilson, of
the University of Chicago, after
careful study, has embodied
these views, based upon my
Skeletal restoration of Nvycto-
sturus. I believe that this
restoration comes nearer to the
real appearance of a pterodactyl

793

That the pteroid bone originated

\\ eet yi i Wt
\ a) WE 5
/ oN

i
y

Fic. 4.—Right front leg of Varano-
saurus Broili, a theromorph reptile from
the Permian of Texas. Seven-tenths
natural size.

704 S. W. WILLISTON

in life than any that has hitherto been published. That the
membrane extended on the neck is of course yet a hypothesis
based upon the mode of development of the parachute in flying
animals of today, and especially upon the structure of the pteroid
bone and its relations to the forearm and shoulder. It is a fact
that this bone seems to be better developed in Nyctosaurus than
in other known pterodactyls, reaching by its pointed extremity
pretty well toward the shoulder. If it was divaricated from the
arm, as its perfect ball-and-socket mode of articulation with the
carpus would indicate, and not inclosed in a muscle at its pointed
extremity, its function as a supporter of a membrane in front of the
elbow can scarcely be taken into consideration. With the mem-
brane extending past the shoulder to the neck it would have had
a distinct function as a ““Spannknochen”’ and not otherwise.
Objection may be raised against the wide expanse of membrane
between the legs. That the membrane extended to the tarsus on
the peroneal side of the legs I think now hardly admits of doubt; the
animals would hardly have been “‘flugfahig’”’ were the legs wholly
free, since the wing membrane would have been too narrow to serve
as a parachute, and since the legs with their attached membrane
must have functioned much like the tail feathers of modern birds
in the control of flight. Rhamphorhynchus gemmingi has been
restored by Zittel without membrane between the legs, but such a
condition must seem impossible for such a flying creature. With
the wings extended and the membrane connected with the ankles,
there must have been a constant and considerable abducting strain
on the legs, which must have required a constant muscular tension
to withstand; and the legs, in the later pterodactyls at least, seem
too frail for such tension. The head of mammals in the horizontal
position is kept in place, not by muscular action, which would be
unbearable, but by the elastic ligament of the neck. Something
like this must have been necessary to withstand the constant
abducting tension of the legs of pterodactyls in flight, and I assume
that this was the function of a tense membrane between the legs,
as well as that of directing flight. It has been suggested that the
border of this membrane connected with the end of the vestigial
tail; possibly that was the case, but, in Nyctosaurus at least, such

THE WING-FINGER OF PTERODACTYLS : 705

an excised membrane would have been little better than none
at all.

That the ribs of the abdominal region extended out into the
patagial membrane on the sides I have given reasons for elsewhere;
I can see no other explanation for their position and lack of curva-
ture in the specimen of Nyctosaurus to which I have referred.

THE TERRESTRIAL DEPOSITS OF OWENS VALLEY,
CALIFORNIA

ARTHUR C. TROWBRIDGE
State University of Iowa

CONTENTS
INTRODUCTION
DEPOSITS AT THE BASE OF THE SIERRA MOUNTAINS
Location and Extent
Topography
Fans and Inter-Fan Areas
Channels and Ridges
Stream Canyons
Bowlder Belts
Slope of the Bajada
Materials
Texture
Structure
TERRESTRIAL DEPOSITS OF THE INYO MOUNTAINS
Pliocene Lacustrine Deposits
Lake Beds in Waucobi Canyon
Lake Beds near Haiwee
Older Deposits at the Foot of the Inyo Mountains
Distribution as Indication of Age
Constitution
Origin
The Present Fans
Distribution
Shape and Topography
Materials
Summary
SOME PROBLEMS OF THE TERRESTRIAL DEPOSITS
Manner of Formation of the Fans and Bajada
Causes of Deposition
Forms Taken by the Deposits
The Transportation of Large Bowlders
Lens and Pocket Stratification
The Dissection of the Sierra Bajada
Deposits of Two Ages at the Foot of the Inyo Mountains
CRITERIA FOR DISTINGUISHING ALLUVIAL FAN MATERIALS
706

TERRESTRIAL DEPOSITS OF OWENS VALLEY 707

INTRODUCTION.

From September 9 to December 1, 1909, the writer in company
with James A. Lane was in the southern half of Owens Valley,
California, studying and mapping the general geology in a semi-
detailed manner, and gathering data on the terrestrial deposits.
The deposits studied particularly lie in the Mt. Whitney Quad-
rangle of the United States Geological Survey, though work was
done in the Olancha Quadrangle, and beyond the limits of both
these sheets, as problems demanded. ‘The results of this work are
used as a Doctor’s thesis in the University of Chicago, this article
being one chapter of that thesis.

The purpose of this paper is threefold: (1) to describe the char-
acteristics of the terrestrial deposits of Owens Valley; (2) to dis-
cuss the causes and processes involved in their deposition; and (3)
to deduce certain criteria whereby materials so deposited may be
distinguished from other deposits such as those of lakes and seas,
even after cementation has taken place. The adequate study of
such deposits should lead to the establishment of criteria by which
terrestrial deposits of earlier ages may with certainty be separated
from marine deposits. It should also lead to the establishment
of criteria for the recognition of various kinds of non-marine depos-
its. It is recognized that such criteria have already been discussed,
and to a certain extent established. But many of these are appli-
cable only to formations of pronounced characteristics, and there are
yet many formations of one age and another whose origins are not
yet established beyond doubt.

Owens Valley is an area about too miles long north and south,
by 12-15 miles broad. It is situated in extreme eastern California,
about east of a point on the coast midway between San Francisco
and Los Angeles. The valley includes the villages of Bishop,
Big Pine, Independence, Long Pine, and Keeler, which can be
reached by the California and Nevada Narrow Gauge Railroad,
connecting with the Southern Pacific at Mina, Nevada.

Physiographically, Owens Valley is located between the Great
Basin on the east and the Sierra Nevada Mountain province on the
west. The east wall of the valley is the west face of the Inyo
Mountains, one of the semi-arid basin ranges, while the west valley

708 ARTHUR C. TROWBRIDGE

wall is the steep eastern slope of the Sierras. Owens Valley,
between these two ranges, is occupied partially by Owens Lake,
and drained by Owens River which flows into the north end of
the lake. The surface of the valley is broken in several places by
the Alabama Hills, Poverty Hills, and a series of recent volcanic
cones and lava flows (see Plate I).

The eastern face of the Sierra Nevada Mountains is a precipi-
tous fault scarp, probably of late Miocene age, attaining a height
of 10,000 ft. above the bottom of Owens Valley. In this slope,
streams and valley glaciers have carved numerous deep canyons,
whose lower portions are choked with drift and whose upper por-
tions are the cirques and bare surfaces of glacially eroded regions.
The rock of the mountains in this region is massive, coarse-grained
igneous rock, chiefly granite. This rock is weathered chiefly by
mechanical processes. Temperature changes and the wedge work
of ice cause pieces of rock varying in size from a fraction of an inch
to a score or more of feet in diameter to break off and roll down the
steep slopes, each piece being broken or worn smaller as it goes.
Plants, animals, and ground water are relatively unimportant as
weathering agents here, because by reason of the steep slopes, they
are not present in abundance. On the other hand, because of these
steep slopes, gravity is more than usually important. Oxidation,
hydration, carbonation, solution, etc., as usually performed by
atmosphere and ground water, do not take place sufficiently rapidly
to produce great results on the rocks before these last are disrupted
and taken away. That is, the mechanical processes of weathering
and transportation take place more rapidly than the chemical
processes, and the result is arkose material carried down the moun-
tain canyons and deposited in the valley below. These are the
materials to be described as the terrestrial deposits of the valley.

Unlike the Sierras, the Inyo Mountains contain both igneous
and sedimentary rock, in about equal abundance. Ordovician,
Carboniferous, and Triassic sedimentary formations have been
interbedded with Triassic lavas, and intruded by Cretaceous
granite and diorite. Though these mountains are not so high by
4,000 ft. as the Sierras, and the slopes are not so steep, still here
also mechanical processes of weathering keep ahead of chemical

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TERRESTRIAL DEPOSITS OF OWENS VALLEY 709

processes, this being due partly at least to the fact that the Inyo
Mountains receive little precipitation, and the moisture necessary
for chemical processes is lacking. Here also canyons have been cut
by streams, and material has been transported to the valley and
. deposited, but unlike those of the Sierras these streams are inter-
mittent, and carry material only after the infrequent rains. The
Inyo Mountains have not been glaciated.

The deposits considered in this paper occur along the east foot
of the Sierra Mountains on the west side of the valley, and discon-
tinuously along the west front of the Inyo Mountains, which border
the valley on the east. The phenomena on the opposite sides of
the valley are sufficiently unlike to warrant description separately.

DEPOSITS AT THE BASE OF THE SIERRA MOUNTAINS
LOCATION AND EXTENT

Within the area of the Mt. Whitney Quadrangle, terrestrial
deposits at the east base of the Sierra Nevada Mountains cover a
belt 1-7 miles wide. In the Olancha Quadrangle to the south,
-corresponding deposits extend for many miles in a narrow and
more or less disconnected belt.

At the north, the plain of the terrestrial deposits is overlain by
recent lavas and volcanic cones. Northwest of Owens Lake the
alluvial deposits lie against the west edge of the Alabama Hills,
and extend around the north and south ends. Two narrow con-
tinuations of the deposit extend through gaps in these hills, and
deploy slightly on the east side. Elsewhere the plain joins the
flat bottom of Owens Valley along a more or less distinct line. On
the west side the plain is limited sharply by the foot of the
mountains.

In the aggregate, the deposits cover about 175 square miles in
the Mt. Whitney and Olancha quadrangles.

TOPOGRAPHY
FANS AND INTER-FAN AREAS
Topographically, this plain of pluvial and fluvial deposits takes
_ the form of a series of fans joined together at their lateral edges.
At first glance, either in the field or upon the topographic maps,

710 ARTHUR C. TROWBRIDGE

it seems to be a continuous plain sloping from the mountains;
but studied in detail, it resolves itself into low, gently sloping fans
separated by broad, ill-defined, shallow depressions. The fans
deploy and become less distinct at a distance from the mountains;
the depressions are therefore broader, deeper, and better defined
close to the mountains. At its outer edge, the topography of the
deposits approaches a plain, in which neither fans nor inter-fan
areas can be distinguished.

The axes of the fans are on lines which are continuations of
canyons in the mountains; the depressions are between the mouths
of the canyons.

From Owens Lake north, the following fans can be distinguished :
those of Richter, Tuttle, Lone Pine, Hogback, George, Bairs,
Shepard, Pinyon-Pine, Oak, Thibaut, and Sawmill creeks. The
last three are small though sharply defined.

A few notes taken north of Lone Pine Creek are here copied,
in so far as they refer to the topography of the fans:

The fan opposite Lone Pine Canyon is sharply set off from the fan of Hog-
back Creek to the north. Beginning at the mouth of the canyon, it spreads
promptly to the north, a distance of about half a mile at the immediate foot
of the mountains, and one and one-half miles within a distance of a mile from
the mountains. Farther from the mountains, it joins the fans on either side,
and its distinctness is there lost. Its north edge is fairly distinct for two miles
from the mountains, being markedly higher than the broad, irregular, linear
depression between it and the fan of Hogback Creek. This depression is dis-
tinct near the mountains, but becomes gradually shallower and narrower
away from the mountains, until the two fans coalesce two miles or so out. . . . .
From the depression, the slope of the fan of Hogback Creek shows a distinct
TISGa ecors. The south side of the fan of Shepard Creek is not especially
well developed, though it is set off distinctly from the fan to the south. The
depression between these two fans is about 200 ft. below their tops, and is one-
fourth to one-half a mile broad. .... North of the fan of Shepard Creek, the
surface declines and does not again reach the high level of this fan as far as the
alluvium can be seen.

The streams have a distinct tendency to leave their fans for
the depressions between. Shepard Creek now flows in the depres-
sion south of itsfan. The North Fork and South Fork of Oak Creek
have joined in the depression between their respective fans. At
some time they were undoubtedly parallel streams. The photo-

TERRESTRIAL DEPOSITS OF OWENS VALLEY Tata

graph (Fig. 1) shows the two fans, South Fork flowing in the low
place, and North Fork leaving its fan for the depression. This
shifting of streams to the inter-fan areas is suggested as a common
and efficient process in the tying together of fans, making piedmont
alluvial plains, or bajadas.* By this shifting, fans are made between
fans, tying them together and tending toward the union of the fans
into one plain.

CHANNELS AND RIDGES

Low ridges and shallow depressions on the individual fans con-
stitute topographic features of a second order. These are the

Fic. 1.—A photograph of the fans of Oak Creek, showing South Fork (ab) flowing
in the inter-fan depression, and North Fork (cd) leaving the fan to join South Fork in
the depression.

channels and depositional features of the streams which deposited
the fans. The depressions are more noticeable than the ridges.
The depressions are, as a rule, about ro ft. deep and less than too
ft. across, though at a maximum they reach a depth of 20-25 ft.
and a width of quite too ft. Their bottoms are usually flat and
their slopes as steep as the material will permit. The elevations
are less numerous than the depressions, and have less relief. They
are seldom more than 5 ft. above the surrounding plain, and their
height in many cases is only equal to the diameter of the individual
bowlders of which the ridges are composed. The ridges consist
t The term bajada has been suggested by C. F. Tolman (Jour. Geol., XVII [1909],

141) to replace the longer term commonly in use. It has the advantage of brevity,
but lacks the explanatory value of the older term.

Te ARTHUR C. TROWBRIDGE

of mere divides between channels and of lines of bowlders bordering
the channels.

In keeping with their origin, the depressions and ridges are
radiate in their arrangement. At the head of each fan, these fea-
tures are few; toward the outer edge they are numerous; but at
the extreme edge they are again rare. Three miles from the edge
there are probably 50 channels, for one close to the head, and some-
thing like that proportion between the same three miles from the
edge and the outer edge itself. Channels which, near the head of the
fan, are close together, diverge outward, and each may break up
into other channels, each less deep and less broad than the one
from which it springs. Quite commonly these channels lead to
depressions between fans and disappear.

It is clear that these channels on the fans mark the courses of
the distributaries from the fan-making streams. The streams
branched again and again, some of the distributaries reaching the
inter-fan depressions and flowing off through them. It is equally
clear that some of the elevations are merely inter-distributary
divides. The origin of the ridges bordering the depressions is not
so clear. Possibly they are in principle natural levees, built as the
waters overflowed their channels. It is understood that these are
the streams which deposited last on the surface of the fans. In the
building of the bajada, the channels undoubtedly shifted frequently,
those of one time being filled up and a new set formed during periods
of greater deposition following heavy rains or the rapid melting of
snow in the mountains.

THE STREAM CANYONS

The streams of the bajada do not now distribute over the fans,
but flow in deep, steep-sided, canyon-like valleys; that is, the
bajada is being dissected (Fig. 2). This is true to a greater or less
extent of all the streams which have played a part in the deposition
of the plain.

The canyons in the bajada vary in depth from 20 ft. to 250 ft.,
and average about 200 ft. in width. The depth is determined by
the size of the stream, the height of the fan, and the position of the
stream on the fan. The most pronounced canyons are those of

TERRESTRIAL DEPOSITS OF OWENS VALLEY FL

Carroll and Lone Pine creeks, which are large streams flowing in the
high central part of well-developed fans. Carroll Creek canyon is
250 ft. deep at the head of the fan, and shallows to less than 50 ft.
at the edge of the bajada. Shepard Creek is almost as large as
elther of the two streams previously mentioned, but it flows on
the side of its fan, where the surface and gradient are lower, and
its canyon is only 30 ft. deep. Hogback Creek has cut deeply at
the head of its fan, but farther out, where the stream has shifted
to the side, there is little intrenchment.

Fic. 2—The canyon of Carroll Creek in the Sierra bajada.. The dark strip
consists of trees 20 ft. bigh.

These canyons are the most conspicuous topographic features
of the bajada. They clearly follow the building of the bajada, and
were excavated under different conditions. They therefore have
both an expository and a historical value. Problems connected
with them will be discussed later.

BOWLDER BELTS

A fourth topographic feature of the bajada consists of almost
innumerable lines of bowlders which, though primarily a matter
of the constitution of the bajada, affect the topography in a minor
way.

These lines of bowlders have a radiate arrangement similar to
that of the channels and ridges. The bowlders are so close together

714 ARTHUR C. TROWBRIDGE

as to make low and discontinuous ridges, which by winding his way
among the bowlders one may in some instances be able to cross
without climbing. ‘The height of the ridges is determined by the
size of the bowlders, and is usually less than to ft. They seldom
consist of more than two thicknesses of bowlders.

THE SLOPE OF THE BAJADA

The slope of the piedmont plain away from the mountains varies
rather uniformly with distance from the mountains. It also varies

Fic. 3.—The slope of the Sierra bajada as seen on the north wall of the canyon of
Carroll Creek.

Fic. 4.—The slope of the Sierra bajada on the south wall of the canyon of Carroll
Creek.

irregularly from place to place along the foot of the mountains.
Along Carroll Creek the slope at the face of the mountain is 18°
and 20° (Figs. 3 and 4). Where it is 20°, the angle decreases to
about 12° a quarter of a mile from the mountains; and where it is
18° at the mountains, the slope is 6-8° a mile or so out. The fan
of Lone Pine Creek has a slope of 6° at the mountains, which de-
creases almost uniformly to a very low slope at the west edge of
the Alabama Hills. The difference between the slopes of the fans
of Lone Pine Creek and Carroll Creek might be due to a diastrophic
tilting, which either did not occur at Lone Pine Creek or did not

TERRESTRIAL DEPOSITS OF OWENS VALLEY TUS

affect the fan there. However, no other evidence of diastrophism
appears at Carroll Creek. Probably the difference is due to varia-
tions in the gradient and size of the two streams in the mountain
canyons, at the time the fans were built. The average slope of the
fans in the valley at the base of the mountains is about that of the
fan of Lone Pine Creek, 6°. The slope is greater along the axes
of the fans than in the inter-fan depressions.

MATERIALS

The material of the Sierra bajada is not well exposed, but some
idea of its upper portion can be obtained. Nothing is known of

Fic. 5.—The largest bowlder seen in the Sierra bajada. The man is 6 ft. tall.
This bowlder lies in the yard of the Cerro Gordo power shanty in Lone Pine Canyon,
14 miles from the foot of the mountains.

that portion lower than 300 ft. from the surface, as there are no
cuts so deep, and well-records are lacking. The material may be
seen in three sets of places: (1) on the unaltered surface of the plain,
(2) on the sides of the shallow channels, and (3) in the walls of the
canyons.

Lithologically, the bajada is composed of material from the
granitic rocks of the Sierras, disintegrated rather than decomposed.
Its components are bits of granite, rather than crystals of quartz
or feldspar. Even the disintegration is not complete, for the mate-
rialis commonly coarse. It is clear that the source of the material
is the mountains, and that it was removed from the parent ledges
mechanically, and transported to its present position by streams,

716 ARTHUR C. TROWBRIDGE

aided in the upper parts of the canyons by glaciers. There is every
evidence of immature weathering of the materials. At the time
the fans were being deposited, the mechanical processes of weather-
ing greatly exceeded the chemical, and transportation was free and
rapid.

TEXTURE

The fans contain all textural grades from pieces the size of small
sand grains and even clay particles, to bowlders more than 20 ft.
in diameter, but pieces less than an inch in diameter predominate.

The most striking and surprising feature of these fans is the
extreme coarseness of some of its materials. Innumerable large

Fic. 6.—Bowlders on the surface of the Sierra bajada. Their size may be esti-
mated from the horse. Picture taken on the fan of Sawmill Creek about a mile from
the foot of the mountains.

and small bowlders appear on its surface, on the sides of the shallow
channels, and on the walls and floors of the canyons. On the
unaltered surface, they occur in radiating lines and belts, roughly
parallel with the radiating channels. They are practically confined
to the higher parts of the surface, where the main streams flowed.
None appears in the inter-fan depressions. More bowlders are
scattered near the heads of the fans than toward the outer edges
but they are not noticeably larger here. They are arranged in
belts or low ridges along the borders of the shallow channels and
are scattered more sparsely on the side slopes. Bowlders are
numerous on the walls and bottoms of the canyons, but without
definite arrangement. The beds of the streams are everywhere
choked with them, and they occur in and along the braided channels

TERRESTRIAL DEPOSITS OF OWENS VALLEY oiaig |

used by the streams in time of flood. Their unusual abundance
in the canyons is doubtless due to the bowlders having been sorted
out in the process of canyon-cutting, the finer material being carried
on and the coarse left.

The whole surface of the bajada considered, the average diameter
of the bowlders is perhaps about 2 ft. but those 8 ft. in diameter
are by no means uncommon. The largest seen are a mile west of
Lone Pine, 6 miles from the mountains, and at the Cerro Gordo
power shanty, on Lone Pine Creek, 13 miles from the mountains.

Fic. 7.—The canyon of Lone Pine Creek in the Sierra bajada. Bowlders appear
almost as large as the two-story house.

The one west of Lone Pine is 10X 20X30 ft. above ground. The
size of the one at the shanty is shown in Fig. 5, the man being 6 ft.
tall. With these exceptional bowlders are thousands of others as
large as 10 ft. in diameter, as can be seen from Fig. 7. The size
and distribution of this coarse material may be seen further in
Figs. 6 and 7. Fine material in the bajada is shown in Fig. 8.

STRUCTURE

Owing to the scarcity of good exposures, the structure of the
materials of the Sierra bajada is not readily determined. The
only satisfactory exposure is near the mountains on Lone Pine
Creek (Fig. 9). Because the canyon walls never stand in vertical
bases, but slump down readily to gentle slopes, they show the

718 ARTHUR C. TROWBRIDGE

texture only, not the structure. The relations of coarse and fine
material can be seen to some extent on the surface of the plain.

As has been shown above, the coarse and fine materials are more
or less separated on the surface of the plain. There are consider-
able stretches, usually the lower areas, where the surface material
is all fine. Such areas are interrupted by narrow belts of large
bowlders. If the structure of the whole plain were judged by its

Fic. 8.—Fine material in the Sierra bajada seven miles from the mountains

surficial aspect, the material could be known to be roughly sorted
into many narrow radiating belts of coarse materials, and broader
belts of fine materials. Presumably these lines would not have the
same position horizontally for any considerable vertical section, as
the stream channels undoubtedly shifted and distributed often.

So far as cuts in the bajada show, the materials consist of a
mixture of large blocks of granite, bowlders not so large, angular
fragments the size of cobbles, tiny angular bits of rock, sand, and
clay. Where any considerable vertical section is seen, these differ-
ent grades are sorted into indefinite lenses and pockets. There are
no definite layers of great extent. Divisions of material are no-
where seen to be continuous for as much as too ft. Some small

TERRESTRIAL DEPOSITS OF OWENS VALLEY 719

exposures show material which is apparently unstratified. Even
where sorted into lenses or irregular areas, there is a considerable
mixture of all sorts of material in each division, each merely
averaging a little coarser or a little finer than its surroundings.

All materials are clearly water laid, but under conditions which
allowed of very poor sorting.

The structure and texture of the materials are brought out best
by detailed descriptions and photographs. Such illustrations are
given below and in Figs. 9, ro, 11, 12, and 13.

Fic. 9.—A section in the Sierra bajada from the south wall of Lone Pine Canyon,
3 mile west of the Cerro Gordo power shanty.

1. Two hundred to three hundred yards above the power shanty
on the south wall of the valley of Lone Pine Creek, wash and gravity
have exposed the material almost continuously for a distance
of about roo ft. vertically. The section consists of both fine and
coarse material roughly separated from one another. ‘There are
two horizons of coarse bowlders, one 20 ft. from the top. and the
other about 30 ft. from the bottom. In the upper horizon the
bowlders are fairly well rounded, and range up to 4 ft. in diameter,
the average being about 1 ft. In the lower zone of bowlders there
is greater range in size. There are numerous pieces 6 in. through,
and several 6 ft. or so in diameter. The sorting is very slight.
Between these two horizons the materials are mostly fine, though
large bowlders are not entirely absent. Immediately above the

720 ARTHUR C. TROWBRIDGE

lower zone of bowlders is a fairly well-defined bed of gravel, the
constituents of which average 3-4 in. in diameter. Between this
gravel layer and the upper zone of bowlders, the material differs
in different parts of the cut, the structure being decidedly pockety.
In one place the fine gravels grade into the coarse bowlders above;
in another, there is a body of clay between the two; in another, the
gravel layer does not appear, and clay separates the two beds of
bowlders (Fig. 9).

2. A six-foot cut a mile from the mountains shows a matrix
of clay and sand in which there are angular fragments averaging

Fic. to.—Roughly sorted materials of the Sierra bajada on George Creek

to in. through, with occasional bowlders 3 ft. in diameter. The
bowlders are angular or subangular, and none are well rounded.
They are not abundant enough to touch one another. There
is apparently no sorting.

3. A hundred yards above the last section, the material is rudely
but distinctly sorted. At the bottom there is a fairly uniform layer
of angular gravel, averaging 4 ft. in thickness, of which the upper
1 ft. give place at the east end to a projection downward of a
pocket from the coarse layer above. ‘There is little clay in the cut,
and the fragments of rock are abundant enough to touch one another.
The pores are filled with coarse, arkose sand, loosely packed.

4. The last section gives place, within a few feet, to unsorted
material entirely similar to that of section 2. From here to the
mountains the sorted and unsorted materials occur with about

TERRESTRIAL DEPOSITS OF OWENS VALLEY 721

equal frequency, in the same position relative to the stream and
to the surface of the fan.

5. Material is exposed on the Mt. Whitney trail through the
Alabama Hills. It is composed of rounded or partly rounded
granitic bowlders, up to a foot in diameter, with a sparse matrix
of granitic pebbles. Though stratification is not apparent, all
material is clearly water laid (Fig. 12).

6. On Dietz Creek, just above its junction with Tuttle Creek,
material is exposed. It is a mixture of very fine angular fragments

Fic. 11.—Unstratified material on George Creek. This section occurs within only
a few feet of that shown in Fig. to.

with material having the texture of coarse sand. The fragments
are not so angular as pieces just broken by weathering. They
seldom exceed a half-inch in diameter, and the average is about
=}, of aninch. The finer material consists of arkose, flakes of mica,
grains of pyrite, and of ferro-magnesian minerals, being almost as
common as quartz. ‘The coarse and fine materials are unassorted.

From these descriptions and photographs, the following charac-
teristics of the materials are shown:

1. The material was derived from the rock of the Sierra Nevada
Mountains.

OP? ARTHUR C. TROWBRIDGE

2. It is the result of immature weathering in the mountains.

3. In texture the materials range from clay-like particles, to
bowlders 30 ft. in diameter.

4. Some of the large bowlders are ice-shaped, and some have
been shaped slightly by water.

5. Stratified, partly stratified, and entirely unassorted materials
occur in something like equal proportions.

6. Where stratification exists, the materials are sorted into
lenses and pockets, never into uniform, continuous layers.

Fic. 12.—A pocket of stratified gravel in the Sierra bajada seven miles from the
mountains on Lone Pine Creek.

7. The materials become gradually finer as distance from the
mountains becomes greater, at least so far as sub-surface material
is concerned.

8. No fossils were found in the material.

These features will be discussed after the deposits at the foot of
the Inyo Mountains have been described.

TERRESTRIAL DEPOSITS OF THE INYO MOUNTAINS

Terrestrial deposits are represented in the Inyo Mountains by
two distinct types of materials of two distinct ages. They will
therefore be discussed separately.

No description of the terrestrial deposits of Owens Valley, and
no discussion of the older deposits at the foot of the Inyo Mountains
would be adequate without mention of certain lacustrine clays and

TERRESTRIAL DEPOSITS OF OWENS VALLEY 723

sands in Waucobi Canyon, described by Walcott,’ and in the vicin-
ity of Haiwee described by Turner,’ Fairbanks,3 and Campbell,’
even though such mention leads beyond the confines of the Inyo
Mountains. Both these deposits were seen by the writer, and they
are here discussed in so far as they may be used as a type of lacus-
trine deposits. Walcott’ and Spurr® have interpreted these deposits
in slightly different ways, but both agree that they are lake deposits,
and as such they will be described. Discussion as to whether they
record great recent uplift of the Inyo Mountains, as according to

Fic. 13.—Unsorted material of the Sierra bajada

Walcott, or were deposited in a deep, widely distributed lake, as
Spurr contends, is not in place here, though such discussion is
given in the unpublished part of the thesis.

LAKE BEDS IN WAUCOBI CANYON

Waucobi Canyon, or the Waucobi embayment as it is called by
Walcott, is a re-entrant in the west face of the Inyo Mountains a
few miles north of the boundary.of the Mt. Whitney Quadrangle

tC. D. Walcott, Jour. Geol., V, 240-48.

2 Personal communication to Spurr.

3H. W. Fairbanks, Am. Geol., XVII, 60.

4M. R. Campbell, Bull. U.S. Geol. Surv. No. 200, p. 20.
5 Jour. Geol. V, 344-48.

6 J. E. Spurr, Bull. U.S. Geol. Surv. No. 208, pp. 209-10.

724 ARTHUR C. TROWBRIDGE

east of Alvord. In this re-entrant are a series of unconsolidated
and partly consolidated sands, clays, and gravels. They were
traced from wall to wall of the re-entrant, and up the canyon for
some 35 miles. Mr. Walcott reports their continuation almost to
the.crest of the mountains.

There are two more or less distinct phases of this deposit. Near
the north and south walls of the re-entrant are interbedded clays,
limestones, and conglomerates. These materials are mostly sorted
into distinct beds, but are locally arranged in pockets or irregular

ak:

Fic. 14.—Lacustrine limestones and conglomerates, deposited near shore in the
Waucobi embayment. ‘

areas, when seen in sections. Two miles east by northeast of Alvord,
a ledge of limestone and conglomerate outcrops under a low hill
of angular alluvium. The limestone is white, porous, earthy, and
filled with small fossils of gastropods. Other rock has a matrix of
calcium carbonate, but contains enough pebbles to make it conglom-
eratic, though the pebbles are seldom in contact. The stony matter
is fairly well rounded. In size its pieces reach 6 in. in diameter,
though the average is about rin. The pebbles are mostly of sedi-
mentary rock, but with some granites. All the material is local.
A series of exposures along the main road 13 miles southeast
of the fruit ranch of J. S. Graham, at the southeast margin of the
re-entrant, shows well the constitution of the beds. All the mate-
rial is irregularly sorted. In some places it is of light-yellowish

TERRESTRIAL DEPOSITS OF OWENS VALLEY 725

clay, which contains enough lenses and pockets to give it a bedded
aspect. In other places it is made up of alternating layers of
gravel and clay, the latter containing bowlders in many places
ilies 14):

Just below these coarse, roughly sorted materials on the main
road, the constitution changes abruptly to sandy clay, arranged
in continuous, uniform, apparently horizontal layers. The change
from coarse, poorly sorted conglomerates to fine clays takes place
within 500 ft. These clays appear all the way to the mouth of the

Fic. 15.—Lacustrine sand and clay in the Waucobi embayment. The layers are
continuous and of uniform thickness.

canyon, as erosional hills about too ft. high, and in the valley
walls. Most of the clay is fine, becoming white dust when powdered.
Some layers are sandy and some calcareous. They are not usually
firmly cemented. Layers 1-10 ft. in thickness can be traced con-
tinuously along the hills (Fig. 15).

These are doubtless lake deposits, the coarser marginal con-
glomerates being the littoral phase, and the centrally located clays
and sands having been deposited in quieter, deeper water, farther
from shore. The fossils have been determined by Dr. Dall as
Pliocene to recent. As the beds lie unconformably under Quater-
nary alluvium, they are probably Pliocene or early Quaternary
in age.

726 ARTHUR C. TROWBRIDGE

LAKE BEDS NEAR HAIWEE

Toward the south end of Owens Valley, in the vicinity of Haiwee
post-office, there is a series of calcareous and arenaceous lake beds.
They were seen by the writer 3 mile southwest, 1 mile east, and 4
mile northwest of the post-office. They are fine, white, and distinctly
bedded. East of the post-office, the beds dip 8° to the northwest.
Northwest of the post-office they dip 14° north. They were best
seen 3 mile northwest of the post-office, where a hill 175 ft. exposes
them from top to bottom. They consist of light-colored, siliceous

Fic. 16.—Unconformity between Quaternary conglomerates and Pliocene lake
beds north of Haiwee. Some of the bowlders of the conglomerate are composed of the
underlying clays.

fine clays or shales. In the lower part of the exposure numerous
small flat bodies of gypsum occur. Most of the plates lie parallel
with the beds, but in some places they appear as secondary bodies
along joints and faults.

The lake beds here are covered with a hard, coarse conglomerate
derived from the Coso Mountains to the east. The lake beds and
conglomerates are unconformable. The conglomerate lies on the
very irregular surface of the truncated edges of the dipping beds of
clay, the surface between the two having a relief of about 15 ft.
(Fig. 16). The constituents of the conglomerate are chiefly granite,
sedimentary rock, and scoriaceous basalt, but near the contact many
large fragments of the underlying clays are also included. The

TERRESTRIAL DEPOSITS OF OWENS VALLEY HOT

conglomerates must be as old as the early Quaternary. The hill
on which they occur is far from the Coso Mountains and separated
from them by numerous valleys, similar hills, and more lake beds.
The lake beds are then pre-Quaternary, probably Pliocene, and
correlated with the similar beds in Waucobi Canyon. No fossils
were found here.

OLDER DEPOSITS AT THE FOOT OF THE INYO MOUNTAINS
Bearing in mind the main characteristics of the deposits
described above, and accepting the idea of their lacustrine origin,
as we are apparently forced to do, we can proceed to a description

Fic. 17.—Low hills of old deposits surrounded by present-day fans, northeast of
Mt. Whitney station.

and interpretation of the older deposits of terrestrial material at
disconnected points along the foot of the Inyo Mountains.
Distribution as indication of age.—At several places, most notably
northeast of Mt. Whitney station and east of Citrus, hills of ter-
restrial material rise 100 ft. above fans which are now in process
of making about them. The materials of the hills differ from those
of the fans in texture, and in the fact that they are cemented.
Along the west face of the mountains immediately northeast
of Mt. Whitney station, an exceptional series of events is recorded
by the nature and relations of the alluvial deposits. Two hills,
roo ft. or more in height, occur half a mile apart, and half a mile
from the foot of the mountains. Between and around these hills
the lower surface is covered with the typical alluvium of the region.
The hills themselves are of gravel and sand. Evidently a great

728 ARTHUR C. TROWBRIDGE

deposit was laid down here, its remnants being represented by the
hills. Conditions changed so that erosion took place, the old
deposit being dissected into hills and valleys. Later, as the streams
were brought to adjustment again, they deposited new fans among
the remnants of the old deposit (Fig. 17).

Due east of Citrus, a series of low spurs projects from the foot of
the mountains into Owens Valley. At the foot of the mountains they
stand 50-75 {t. above the plain, and become gradually lower west-
ward. ‘They are not in direct contact with the present fans, though
fans occur at lower levels north and south of them. These projec-
tions are not at the mouths of present canyons (Figs. 18 and 109).

Frc. 18.—Lacustrine beds (light colored) lying against rocks of the Inyo Moun-
tains (darker rock to the right), east of Citrus. Stratification may be seen in the left
center. Bs)

The deposits in Mazourka Canyon, the canyon east of Aber-
deen, and on the flanks of the mountains east of Keeler should also
be included in this category. In the two canyons, older cemented
gravels occur as distinct, flat-topped, but eroded terraces, 50 ft.
above the stream beds. East of Keeler, hills of conglomerate
rise 200 ft. above present alluvial surfaces.

Constitution.—The materials of the older deposit at the foot of
the Inyos differ from those of the Sierra bajada in various ways;
especially in (1) lithological composition, (2) texture and shape of
pieces, (3) structure, (4) cementation.

1. This deposit is made up of fragments of all rocks occurring
in the Inyo Mountains, from which they are derived, including
both igneous and sedimentary rocks.

TERRESTRIAL DEPOSITS OF OWENS VALLEY 729

2. The constituents have not a great range in size. In place
of large bowlders, the coarser materials are large-sized cobbles or
very small bowlders. Texturally, the fine material is sand or clay.
The average size of particles is probably less than half an inch in
diameter. Bowlders even as large as 1 ft. in diameter are wanting.

In the Sierra bajada the pieces of rock are either ice-shaped, or
they are almost as angular as when broken off by weathering.
Here the effects of glaciation are not seen. The fragments have
been worn to pebbles, few sharp or irregular edges appearing.

Fic. 19.—Close view of the older deposits east of Citrus. Note the layered
structure and the dip of the beds.

They are in general well rounded, having been shaped by the action
of water.

3. These materials are arranged in definite, continuous layers of
gravel and sand. ‘The layers can be traced the whole length of the
various outcrops as beds of nearly uniform thickness. East of
Citrus a definite, continuous layer of clean, fine gravel, uniformly
2 ft. thick, overlies a layer which is a mixture of small angular frag-
ments, sand, and clay. Northeast of Mt. Whitney station the
talus from a deep cut is of uniform-sized cobbles and sand. The
stratification of this material may be seen in Figs. 18 and ro.

Wherever exposures were seen east of Citrus, the beds have an
appreciable westward dip (away from the mountains). Clinometer
readings vary between 8° and 18°. The direction of dip is nearly

730 ARTHUR C. TROWBRIDGE

constant. No faults, minor folds, or other evidences of diastro-
phism were seen. This dip may be depositional, or the beds may
have been tilted to their present position by an uplift in the moun-
tains. Eighteen degrees is a high dip to be considered depositional
when the material is fine.

4. The older deposit shows a tendency toward cementation,
and some layers are firmly cemented. In general it is the layers
of coarse material, originally more porous, that are cemented.

In the beds east of Citrus mentioned under (3) above, the upper
layer of gravel is cemented to firm conglomerate. It is so solid as
to ring under the hammer and to need more than one hard stroke

Fic. 20.—A stream terrace of older alluvium in Mazourka Canyon

before it is broken. The material of the finer layer below cannot
be picked out by the hand, but yields readily to the hammer. The
gravel layers are almost everywhere so indurated that they stand
out conspicuously, the determination of dips thus being made easy.

The above characteristics hold for all the deposits of older
materials at the foot of the mountains, with the exception of those
in Mazourka Canyon. The deposits in this canyon belong to the
older deposit, for they occur in terraces above the present deposi-
tional surfaces, but the materials are in some respects different.
Areally considered they take the form of the canyon in which they
were deposited, and thus occur in a long strip. They constitute
more or less definite stream terraces on the sides of the present
valley (Fig. 20). Texturally they are like the deposits along
the foot of the mountains, the chief difference being in the strati-

TERRESTRIAL DEPOSITS OF OWENS VALLEY 731

fication. Instead of being in definite layers, as are the deposits
at the foot of the mountains, the materials in the canyon are in
indefinite lenses and pockets, similar to those of the Sierra bajada,
though on a much smaller scale.

An examination of two detailed sections noted just above Barrell
Springs brings out the difference between these deposits and those
east of Citrus and Mt. Whitney station:

Tal Be ao Angular fragments the size of cobble, and clay.

Tepeliteeeca ls crs Well-sorted, very fine gravel.. Pinches out in both directions.

Ties Aiba. oe Mixture of cobbles and clay. Pinches out upstream.

TEP OURAN a Sats Clay with some small angular bits of rock.

Peete ee ccs Well-sorted, loose, fairly well-rounded cobbles; average size
13 in.; one-inch clay layer in middle.

3 ft....... Mixture of sand, clay, and gravel; little or no stratification;
pockety; contains one bowlder one foot in diameter.

De whbte cases Clay, sand, some gravel; poorly sorted.

Dwele ns ek Fine angular fragments; little or no clay or sand; well

"assorted.

2. Fifty feet down the valley from the last, the following section
occurs:
Be enhiteiera i a Mixture of coarse and fine angular gravel, with clay in the

interstices; average size of constituents 1 in. in diameter;
occasional bowlders 1 ft. in diameter.

1 tt eI Moderately fine gravel; little or no clay; no pieces larger than
3 in. in diameter; pinches out in 12 ft. up valley.

Dim lites aaa: Clay and pebbles intermixed; rude layer of cobbles in middle.

DB Ves a od Ook Fairly well-sorted gravel, coarser at bottom. Pinches out
rapidly in both directions. Loosely packed, interstices not
filled.

Mae LEN erect ai Irregularly bedded bowlders, cobbles, fine gravel, clay.

Digg bya eas Indefinitely bedded fine angular gravel. Average 4 in. in
diameter.

Tame sais tok ard Pockety, coarse gravel, constituents up to ro in. in diameter.

In both sections, the materials are slightly cemented. Nota
single subdivision of one could be traced 50 ft. to the other. For
further details of these materials see Figs. 21 and 22.

It is thus seen that the materials of Mazourka Canyon differ
from the rest of the older deposit at the foot of the mountains in

Wee ARTHUR C. TROWBRIDGE

that it includes coarser materials and has a lens and pocket struc-
ture (cf. Figs. 19 and 21).

Origin of the older deposit at the foot of the Inyos.—It will be seen
from the foregoing that most of the older deposit is sufficiently
unlike the Sierra bajada to lead one to conclude that its mode or
conditions of origin were not the same. On the other hand, if
it be compared with the near-shore phase of the lake beds in Wau-
cobi Canyon, a strong resemblance will be seen: (1) Both deposits

Fic. 21.—Stream deposit in Mazourka Canyon. Compare with Figs. 14 and 15

were formed and eroded before the deposition of the recent alluvium.
(2) Both are firmly cemented, at least locally. (3) They are similar
in texture, both being fine and having a low textural range. (4)
Their stratification is the same, both being sorted into layers. They
are dissimilar in that the constituents of the deposits at the foot of
the mountains are better rounded than those in Waucobi Canyon,
and the former contain no fossils. With such similarities between
these deposits and the lake beds, it seems clear that the older
materials northeast of Mt. Whitney station and east of Citrus are
of lacustrine origin, and belong to the same formation as the lake
beds in Waucobi Canyon and at Haiwee. If so, the lake in which
they were deposited was shallow, and the shore lay against the

TERRESTRIAL DEPOSITS OF OWENS VALLEY 733

mountains immediately to the east. The dissection of the deposit
probably took place subsequent to the uplift of the mountains and
the draining of the lake. If lacustrine beds corresponding to them
were deposited at the foot of the Sierras, they have been covered
and concealed by the more recent alluvium.

The deposits in Mazourka Canyon are obviously not lacustrine,
but of stream origin. They were probably laid down on the floor
of a mature valley, which was tributary to the lake east of Citrus.

Fic. 22.—Photograph to show the shapes of the cobble in the terrace of Mazourka
Canyon.

The differences between these deposits and those along the foot of
the mountains may be taken as differences characteristic of lacus-
trine and fluvial deposits.

THE PRESENT FANS

DISTRIBUTION

Between Mt. Whitney station and Aberdeen there are nine sepa-
rate fans at the foot of the Inyo Mountains. On the map (Plate I) ~
they are numbered 1 to 9, beginning at the south. Of the nine fans,
I, 2, 4, and 8 are large, each covering more than a square mile,
and 3, 5, 6, and 9 are smaller. All of them occur at the mouths
of mountain canyons. The largest one, No. 4, is at the mouth of
the largest canyon, Mazourka, though it is not so well shaped as
the others. Between the mouths of the main canyons and between
the main fans are some patches of alluvium too small to map and
not important in any way. ‘These patches occur at the lower ends

734 ARTHUR C. TROWBRIDGE

of very small valleys. Fans also occur along the mountains outside
the mapped area. They were seen northeast of Aberdeen and at
Keeler.

SHAPE AND TOPOGRAPHY

In general there are two controlling factors in the shapes of the
fans. At their mountainward edges they are confined by the walls
of the mouths of the canyons, from which they take their form.
Their outer edges deploy slightly on the plain. Nos. 2 and 8 extend
about a mile into their canyons, and No. 4 extends still farther up
Mazourka Canyon. Nos. 1 and 3 show deployment on the plain.
No. 2 is made up of two smaller fans, with a depression at their
junction.

The surfaces of these fans are very similar to the surface of the
Sierra bajada, except that all features are on a smaller scale, the
fans, except No. 2, are simpler and remain separate, and these fans
are not now in process of dissection. The individual fans show
numerous radiating channels and low ridges similar to those on the
Sierra plain, but they give the surface here a relief of no more than
7 or 8 ft. at a maximum. The ridges are almost invariably belts
of bowlders. The fans are not dissected as is the Sierra bajada.
The streams still flow on the surface in the radiating channels, but
they flow only after the infrequent rains in the mountains.

The slope of the fans varies considerably from head to outer
edge. Fan No. 8 has a slope of about 10° at its head, 5-6° midway
of its length east and west, and approaches flatness at its outer
edge. Fan No. 1 has a slope of more than 600 ft. per mile in its
upper part. The upper part of fan No. 2 slopes westward 800 ft.
ina mile. This is steeper than the average.

MATERIALS

These fans at the foot of the Inyo Mountains have not been
dissected, and exposures of the material are therefore few and shal-
low. Some data can be collected from surface materials, there are
a few shallow cuts along the channels, and one prospect pit affords
a good exposure.

Each fan is made up of pieces of the kind of rock in which the
canyon back of it is cut. For instance, 99 per cent of the material

TERRESTRIAL DEPOSITS OF OWENS VALLEY oe

of fan No. 8 is granite, the other 1 per cent scoriaceous lava and
slate. All the face of the mountains here is granite, which is bor-
dered along the edge of the Santa Anita flat by slate. Lee’ maps
a volcanic mountain southeast of Aberdeen, which doubtless ex-
plains the occasional fragments of scoriae. The fan northeast of
Aberdeen is composed of bits of granite, gneiss, scoriaceous basalt,
and limestone. All these rocks occur together in the walls of the
canyon. Fan No. 1 is made up largely of bits of lava, sedimentary
rock, and granite. No. 2 is mostly of sedimentary rock and lava,

Fic. 23.—Bowlders on the surface of fan No. 8 north of Citrus. Their size may be
estimated.

with some fragments of granite. No. 3 contains a mixture of sedi-
mentary rock, diorite, and granite, in keeping with the rocks east
of it.

On the surface of the fans there are both coarse and fine materials
arranged as on the Sierra bajada in diverging lines or belts from the
head of the fan.

Though the bowlders are not so large as on the opposite side of
the valley, they are still astonishingly large for the drainage by
which they were transported. The largest bowlders seen were
near the head of fan No. 8, where there are some 10~12 ft. in diam-
eter. On fan No. 2 bowlders are especially numerous. Toward

=W. T. Lee, Water Supply and Irrigation Paper, U.S. Geol. Surv., No. 181, Pl. I.

736 ARTHUR C. TROWBRIDGE

the head of the main fan the entire surface is so covered with them
that a horse cannot travel overit. The average size of the bowlders
is about 13 ft. Their number and size can be seen in Fig. 23. The
photograph was taken from fan No. 8.

These bowlders show little shaping. If fragments were broken
from ledges by the wedge work of ice and gravity, and then the
sharp and irregular edges dulled during a short period of transpor-
tation, their present shape would result. Neither glaciation nor
prolonged rolling has affected them.

mee

Fic. 24.—Angular material in the fans at the foot of the Inyo Mountains

The fine material on the surface of the fans occurs in largest
areas near the outer edges, where there are few bowlders, and the
surface material has about the texture of fine gravel or coarse
sand. A half-mile from the edge it is made of fragments more —
or less shaped by transportation, averaging perhaps 3 in. through,
with some lines of larger bowlders. At the head the surface is
practically covered with bowlders.

Although exposures of material beneath the surface are almost
wanting, a few shallow cuts were seen. The data they afford
follow:

1. In the outer edge of fan No. 8, 4 miles south of Aberdeen,
is a pit. dug as a placer prospect, 1o ft. deep, 15 ft. long, and
5 ft. wide. The material is all fine, there being nothing as large

TERRESTRIAL DEPOSITS OF OWENS VALLEY Tu

as I in. in diameter. The pieces are distinctly angular. The
section follows:

Baie ete Fine clay and gravel, not laminated.
Titan sets) clay

Di Aty anne: fine gravel

Seen ee clay

Bliter yes 2. tee fine gravel

DaliNe ws eae ClAy

2. Ten feet of material are exposed in the fan northeast of Aber-
deen. It is not stratified. Angular bowlders are imbedded in a
matrix of clay.

3. Near the upper end of fan No. 2, a gully affords an exposure.
The section consists of both stratified and unstratified material.
In the unstratified parts, the main constituent is clay, in which are
imbedded numerous angular bowlders. One 35 ft. in diameter
occurs in a mass of clay.

4. Distinctly angular alluvium is shown in Fig. 24.

SUMMARY

It is apparent from the foregoing that there are two sorts of
terrestrial deposits in and at the foot of the Inyo Mountains, of two
distinct ages. The first deposits appear to have been made when
the mountains were low and bordered by a lake: Mazourka Can-
yon had been cut and brought to grade, deposition taking place in
its bottom from its mouth up. The deposits of the time are all
fine, fairly well sorted in Mazourka Canyon,.and very well sorted
in Waucobi Canyon and along the mountain foot.

Conditions so changed that these first deposits were largely
removed by erosion. The change was probably brought about
by the uplift of the mountains, as the later alluvium is much coarser
than the older. After the uplift, new canyons were cut in the
mountains, and new fans deposited among the remnants of the old
lacustrine deposits. This process is still going on.

SOME PROBLEMS OF THE TERRESTRIAL DEPOSITS

The fluvial deposits of Owens Valley, as described above, offer
several problems. In some cases the solutions of the problems are
simple and obviously correct; in others the solution is not so clear,

738 ARTHUR C. TROWBRIDGE

and there is some doubt as to the correctness of tentative conclu-
sions; in still other cases, the solution is entirely hypothetical.
In some cases various lines of explanations may have partial applica-
tion to the observed features. These problems are here discussed
individually.

MANNER OF FORMATION OF THE FANS AND BAJADA
CAUSES OF DEPOSITION

Material was deposited at the foot of the Sierra and Inyo moun-
tains, primarily because of an abrupt decrease in the gradient of the
streams. When the mountains were first uplifted, and precipitation
fell on the slopes, streams formed and flowed swiftly down the
sides, carrying material from their channels. When the base of the
mountains was reached, the carrying power was suddenly and
greatly decreased, and the first deposition resulted.

Once started, other factors tended to increase the process of
deposition. Streams lost volume by sinking into loose material.
This not only reduced the volume of the transporting agent, but
also lessened the velocity of the water remaining at the surface;
both these changes caused deposition.

The average relative humidity of the Sierra Nevada Mountains
is not far from 60 per cent, and that of Owens Valley probably not
more than 40 per cent.t_ When the streams reach the plain, evapo-
ration is increased; hence loss of volume, loss of velocity, and
decrease in carrying power. This would not be so important in the
case of the Inyo Mountains, because the difference in humidity
between mountains and plains is not so great there. However
what little rain falls, is in the mountains rather than on the plains,
and evaporation takes place more rapidly in the latter locality.

Water taken from streams by irrigation so decreases their vol-
ume in some other localities as to aid in causing deposition, but such
is not the case in this region. The Sierra bajada has been under-
going dissection rather than gaining by deposition since man began
to irrigate the lands, and the streams on the Inyo fans, running
only after rains, are not used for irrigating purposes.

« For details of precipitation and evaporation in the valley, see Water Supply and
Irrigation Paper, U.S. Geol. Surv., No. 181, pp. 17-25.

TERRESTRIAL DEPOSITS OF OWENS VALLEY 739

Decrease in volume and consequent decrease in velocity took
place on the plains for another reason also. It rained heavily
or snow melted rapidly in the mountains, and the mountain streams
acquired great volume and velocity. When the rain ceased, or
the temperature dropped below 32°, the flood on the plains sub-
sided from lack of supply from above. This undoubtedly furnished
conditions under which a large proportion of the material of the
fans was deposited.

Glaciation has played a large part in the deposition of the Sierra
bajada. Glaciers prepared immense amounts of material in the
mountain canyons for transportation by streams. At the same
time they furnished great volumes of water to act as the transport-
ing agent during the melting-season. The initial volume and
the load being at a maximum, deposition took place on the plains at
an unusually rapid rate and to an unusually great extent.

FORMS TAKEN BY THE DEPOSITS

Deposition necessarily took place at the foot of the mountains,
at the end of the mountain canyons. ‘The streams flowed on down
over the deposit it had made, until it disappeared; hence the fans
slope away from the mountains. While the stream was depositing
and especially at times when floods were subsiding, channels were
filled, distribution took place, new channels were made and filled,
and water courses changed constantly. In each new distribution
the channels diverged from the mountains. The resulting feature
is broader near its edge than near the head; that is, it is roughly
fan shaped.

In the Inyo Mountains there is little precipitation, the canyons
are far apart and small, and the fans are accordingly too far apart
and have grown laterally too short a distance to have been joined.
The result is a series of separate fans. In the Sierras, the streams
issue at sufficiently small intervals and have built fans of sufficient
size, so that they have coalesced to make a compound fan, pied-
mont alluvial plain, or bajada.

When fans first join, the compound fan is a series of fans, with
low places between. If Oak Creek, Shepard Creek, and Hogback
Creek are considered as types, there is a tendency for streams to

740 ARTHUR C. TROWBRIDGE

leave their fans and locate their main channels in the inter-fan
depressions. Deposition then takes place in the depression, build-
ing it up and making a fan across the edges of two earlier fans.
Presumably streams will shift back to their original positions when
those positions have become lower than the site of the original
depressions, through deposition in the latter. Streams then shift
from fans to depressions, make fans there, shift back, build up the
old fans, shift again, etc. How frequent and important this may
be is not clear. If streams shift freely from higher places to depres-
sions, it is surprising that fans of the bajada stand 200 ft. above
the low places between them. The general relief of the bajada
should be very slight. The water forming depositing streams
probably does not adjust itself freely to the low places, though it is
clear that it does so in many cases. The origin of the diverging
channels is clear.

THE TRANSPORTATION OF LARGE BOWLDERS

One could hardly travel a mile on the Sierra bajada, or see the
heads of the fans at the foot of the Inyo Mountains without asking
how the large bowlders came to their present positions. It is
essentially a problem of the means of transportation of the largest
bowlders farthest from the mountains, for if they can be explained,
the smaller bowlders may be considered to have been carried shorter
distances by the same methods. Probably the most difficult
problems are offered by the largest bowlders, such as those west of
Lone Pine, 6 miles from the mountains, measuring 10X 20X 30 ft.
above ground, and the one at the Cerro Gordo power shanty, larger
than the one first mentioned and 13 miles from the mountains,
and several others in that vicinity about as large.

It is clear that these bowlders came to their present positions’
through the agency of water. Though their size suggests glaciers
as the transporting agents, such an explanation is out of the ques-
tion. The lower limit of glaciation is distinctly marked in the
mountain canyons above. The glaciers did not descend to the
plains. Nor is there anything in the fact of icebergs floating in
a lake. The deposits with which the bowlders are associated are
not lacustrine, and no lake existed in the valley during glacial

TERRESTRIAL DEPOSITS OF OWENS VALLEY 741

times. The surface on which the bowlders lie clearly was made by
running water. The bowlders are so clearly a part of the fans,
and the fans are so clearly running-water deposits, that the bowlders
must be considered to have been transported by running water.

It is also clear that the bowlders were not transported according
to the common and well-known methods of stream transportation.
They have certainly not been rolled along the bottoms of streams in
the usual way. They have not the rounded form characteristic
of such motion. On the surface of the fans, furthermore, it is
impossible for streams to have existed deep enough and strong
enough to have so rolled these bowlders. Such streams would have
to have a depth about equal to the diameter of the bowlders, be
confined in a narrow channel, and flow with a velocity almost incon-
ceivable for a stream. As the bowlders occur on the higher parts
of the fans, water of sufficient depth to have carried them would
have formed a sheet 20 ft. deep over the fans, and 220 ft. deep over
the inter-fan depressions. Even then it would not have been con-
fined to a narrow channel. Also the gradient of the fans is rela-
tively low. Where the largest bowlders are, the slope is not over
6°, and west of Lone Pine not more than 3°. Bowlders much smaller
than these are not now being rolled down the mountain canyons
above, where the streams are sharply confined and the gradient is
very high. The volume of the stream may have been sufficient
to carry them im the canyons when the glaciers were there. The
problem involves transportation on the fans only. They were per-
haps carried to the heads of the fans by glaciers, glacial waters, and
gravity. From there to their present positions, some special
methods are called for.

A clue to a possible manner of transportation for these bowlders
is obtained from observations of run-off water at the side of a pre-
viously dusty road after a heavy rain. Where the running water

‘is but a small fraction of an inch deep, pieces of rock an inch in
diameter are carried down stream. The moving of the large pieces
involves the transportation of a very much greater amount of fine
material. The movement of the large pieces is accomplished by the
removal of fine material from the area immediately down stream
from, and under, the lower part of the large piece. By undercut-

742 ARTHUR C. TROWBRIDGE

ting in front, and then by gravity and the push of water and sedi-
ment from behind, the large piece is pulled and pushed forward
into the depression prepared for it. This process takes place over
and over again, the large piece being moved down the low gradient
in a halting fashion. The depth of the depression into which the
piece falls is never so deep as the diameter of the fragment moved.
Once started in motion, the piece is sometimes carried many times
its own length by its momentum, and by the force of water and
gravity. The motion is usually one of sliding rather than rolling.

It is conceivable that these same methods might operate on
the surface of an alluvial fan, on a scale large enough to transport
bowlders even 20 ft. in diameter distances of several miles. The
bowlder starts from the head of the fan in company with a rela-
tively large amount of fine material. The volume of the stream
varies greatly from time to time, with great differences in preci-
pitation in the mountains, and with daily and seasonal ranges in
the rate of melting of glaciers. Material is deposited and rehandled
time and time again. When the volume is great, fine material is
removed from the front of the bowlder and from beneath its front
edge, while other material is piled against its upper side, and the
bowlder falls, or is pushed, or rolled over into the depression. As
the flood subsides, the bowlder may be almost or completely buried,
but the next flood uncovers it, and the process is completed. With
sufficient time, sufficient variation in volume of water, and sufficient
rehandling of material, huge bowlders may thus be transported
great distances.

Would the slope of the fans be sufficient for such transportation?
In the roadside rill the piece of rock moves a distance several times
its own length, while dropping less than its own diameter. Suppose
the bowlder 20 ft. in diameter moves 4o ft. horizontally, with a fall
of 15 ft.; this would require a gradient of 1,980 ft. per mile. If it
moves 60 ft., with a 1ro-foot drop, the gradient would be 880 ft.
per mile. The average slope of the bajada is about 400 ft. per mile.
This requires that the bowlder west of Lone Pine, 10X 20X30 ft.,
move about 120 ft., or four times its own length, in dropping 10
ft., or about its own smallest diameter, if the proportions observed
hold.

TERRESTRIAL DEPOSITS OF OWENS VALLEY 743

This is conceived to be possible. The process is greatly aided
by the momentum obtained by the bowlder when it first moves
toward the depression. The depression below the bowlder would
not be deep, before the crowding of the material above, and the force
of water and gravity would force the bowlder intoit. The depres-
sion would play out very gradually down slope, giving a constant
gradient down which the bowlder could roll, slide, or creep.

Obviously this process would operate to best advantage where
there was the greatest volume of water, and where fluctuations of
water were greatest; that is, along the main channels of the fans,
and on the Sierra fans rather than at the foot of the Inyo Mountains.
Bowlders are usually arranged in lines related to the channels,
and they are more abundant and larger on the Sierra bajada than
at the foot of the Inyos. If this method of transportation of large
bowlders is not adequate, methods which are, are not known.

LENS AND POCKET STRATIFICATION

It was shown above (pp. 717-22 and 735-37) that the materials of
the fans of the region are but crudely sorted, and that the different
textural grades take the forms of lenses and pockets, rather than
definite and continuous layers. No textural division was traceable
more than 50 ft. in any cut, before it played out in one direction or
another. The explanation of this seems clear.

On the surfaces of all the fans in the region are numerous
radiating channels and low ridges. In Mazourka Canyon, these
channels are braided in almost all directions, though along lines
trending generally down valley. These surfaces represent the last
deposition on the respective fans. Beneath the present surface
there must be many similar surfaces, made and buried as the fan
was built.

When flood waters flow over a fan, radiating channels are formed.
As the flood subsides, or if the waters are overloaded otherwise,
deposition takes’ place in the channels. The channels are filled
with whatever grade of material the stream finds itself unable to
carry, and the stream is forced over the side. It then makes a
new channel, fills it, and overflows to repeat the process. The fan
grows by the addition of long narrow strips of material, sorted

744 ARTHUR C. TROWBRIDGE

roughly into different textural divisions. These strips diverge
from the axis of the fan.

No straight section can be cut in such a deposit without cutting
the filled channels. If the cut is longitudinal, practically all the
channels will be cut obliquely and at low angles; a few might be
cut at right angles. If the fan is dissected by streams cutting down
in the old channels, buried channels will still be cut obliquely, as
distribution does not take place along lines exactly parallel with
previous distributaries.

The filling of a buried channel, when cut along a straight line
oblique to the original channel, is exposed as a lens whose length
and degree of pinching out depends primarily on the obliquity of
the line of cut. A channel filled, buried, and then cut at right
angles reveals itself as a pocket in section, the size and shape of
which depends on the size and shape of the channel. Continuous
layers, uniformly thick can occur only where the depositing dis-
tributary was long, straight, and contained uniform material, and
where the filling was cut along a straight line exactly parallel to
itself. Obviously where exposures are along longitudinal cuts,
the result is many lenses, a few pockets, and practically no con-
tinuous layers.

That this is the correct explanation of the lenses and pockets of
the fans of the region is shown by a correspondence in size between
lenses and present surficial channels. On the Sierra bajada, the
channels are about 8-10 ft. deep on the average, and the lenses and
pockets are about 8-10 ft. thick at their thickest parts. The present
flood surface in Mazourka Canyon has a relief of about a foot; the
lenses in the older alluvium near by have just about that thickness.

It is understood that any deposit from distributing or anasta-
mosing streams will reveal a lens or pocket structure in straight
cuts. The principle probably applies to all alluvial fans, pied-
mont alluvial plains, flood-plain deposits, glacial valley trains and
outwash plains, and deposits on tidal deltas.

THE DISSECTION OF THE SIERRA BAJADA

A variety of events might bear causal relations to the dissection
of alluvial fans. Among them are changes in climate, uplift of the

TERRESTRIAL DEPOSITS OF OWENS VALLEY 745

fans, down-warping of their surroundings, etc. Such events and
resulting processes may be complex. The cause of dissection in
this case, however, seems to be the cessation of glaciation, and the
process seems simple.

All the material seen in the bajada, even to the bottoms of the
canyons, shows evidence of glacial wear. Before the mountain
canyons were glaciated, the fans must have been smaller and lower
than now by an amount at least equal to the depths of the canyons.
Glaciers were formed, which carved great amounts of material from
the heads of the canyons, carried it to their lower ends, and, melting,
supplied great quantities of débris-laden waters to flow out over
the fan. The fans grew rapidly and became large, out of all pro-
portion to those at the foot of the Inyo Mountains, which were
not affected by glaciers.

When the glaciers in the mountains had melted away, these
enlarged fans were dissected, for the same reason that a valley
train is trenched. The streams now reach the fans with less
material than they carried when the glaciers existed, and are able
to erode material from the fan.

The matter may be looked at in another way. The pre-glacial
fans, being lower than the present ones, had lower gradients and
made a sharper break in gradient at the foot of the mountains, and
deposition progressed. Now that the fans are higher, their gradi-
ents are steeper, and the break in gradient at the foot of the moun-
tains is not so great, and the streams flow out over the fans with their
velocities less checked than formerly. This means at least that
there will be less deposition on the present fans, and, taken with
the fact that the streams have less load, plays a part in the erosion
of the fans.

Presumably the canyons will be deepened almost or quite to
the bottom of the glacial material. This depth has nowhere been
reached as yet.

DEPOSITS OF TWO AGES AT THE FOOT OF THE INYO MOUNTAINS

The older deposit at the foot of the Inyo Mountains is here
considered to be a lacustrine deposit, coinciding in age with the
lake beds in Waucobi Canyon and those near Haiwee. Ii this be

746 ARTHUR C. TROWBRIDGE

correct, the explanation of the dissection of these deposits and the
later deposition of fans is not complex.

A lake existed in Owens Vailey, probably in Pliocene times, and
deposits were laid down in it on the flanks of the mountains. The
lake was drained or dried up, and the mountains were probably
uplifted. Dissection of the deposits thus exposed and uplifted
followed. After erosion had removed a large part of the lacustrine
deposit, deposition began at the foot of the mountains, and the
present fans have been built up among the remnants of the old
lacustrine deposits.

CRITERIA FOR DISTINGUISHING ALLUVIAL FAN MATERIALS

In conclusion we may bring together the distinguishing features
of the materials of fans, as seen in this region. The region affords
especially good facilities for the drawing of such conclusions, as it
contains both running-water and standing-water deposits of similar
ages.

Deposits on alluvial fans may be distinguished from those in
still water, either lacustrine or marine, as follows:

1. In alluvial fans, coarse material has a wide distribution as
against confinement to a narrow zone near shore in standing-water
deposits.

2. Textural range in single exposures is large in fan materials.

3. Fan materials are not in general so well sorted as deposits
in standing water.

4. The beds and surfaces of fans are likely to have slopes of
6-18°, as against o-3° in standing-water deposits.

5. Fan materials are likely to have fewer and different fossils
than deposits in standing water.

6. Fan material has a lens and pocket stratification, as against
a sorting into more or less uniformly thick horizontal layers, as in
lakes or seas. .

7. Huge bowlders widely distributed vertically and horizontally
in a deposit indicate that it was deposited by running water, and
with a large proportion of fine material; that is, they indicate that
the material is part of an alluvial fan deposit, except in cases where
glaciers have affected it, or where standing waters could have

TERRESTRIAL DEPOSITS OF OWENS VALLEY 747

recelved icebergs, or where basal conglomerates are formed near
shore.

8. Theoretically, fan material will be more compact at first
than still-water deposits of the same textural grade, as each particle
drops to the bottom with greater force and the film of water around
each particle is not so thick. After water is drained from both
deposits, still-water deposits are likely to be more cracked than
fan materials, because they contract more. After cementation,
still-water deposits, say of clay, will have more veinlets than fan
materials of the same texture.

ON CORUNDUM-SYENITE (URALOSE) FROM MONTANA

AUSTIN F. ROGERS
Leland Stanford Junior University

Specimens of a corundum-bearing rock from the property of the
Bozeman Corundum Company, fourteen miles southwest of Boze-
man, Gallatin County, Mont., were obtained for Stanford Uni-
versity by Mr. R. M. Wilke of Palo Alto, Cal. No information
concerning the country rock could be obtained except the state-
ments of Pratt in his monograph on corundum:’ ‘‘The corundum
seams vary from a few inches to three feet in thickness. . . . . Boze-
man: Fourteen miles southwest of this town corundum is found
in syenite.”’ From this it would seem that the country rock as a
whole is a syenite with bands or seams of the corundum rock.
These bands, the writer will show, are corundum-syenite. The
rarity of this type of igneous rock accounts for the present paper.

Corundum-syenites have been described only from the Urals,’
from eastern Ontario,* and from the Coimbatore district, India.4

The corundum-syenite is a medium to coarse-grained, gray-
mottled, more or less banded rock, the banding due principally to
the fact that the biotite flakes are mostly in parallel position, though
the other minerals are occasionally in rough, parallel position.
The gneissoid corundum-syenite, as it may be characterized, is
composed of microcline-perthite, biotite, and corundum with sub-
ordinate sillimanite, muscovite, zircon, and baddeleyite. The
feldspar is for the most part a perthitic intergrowth of microcline
and albite, though one slide shows plagioclase, orthoclase, and
microcline without any perthite. On a section of the microperthite
parallel to {oor} the microcline has an extinction angle of 113°,
and the albite, one of 43°. In this section the albite shows only
very faint albite twinning. On a section parallel to joro} the
microcline has an extinction of —3° and the albite, one of +20°.

t Bull. No. 269, U.S.G.S:, 133, 144 (1906).

2 Morozewicz, Min. u. petr. Mitth., XVIII, 217 (1808).

3 Miller, Rept. Bureau of Mines, Toronto, Canada, VIII, Part 8, 210 (1899).

4 Holland, Mem. Geol. Surv. of India, XXX, Part 3, 169 (1901).

748

ON CORUNDUM-SYENITE FROM MONTANA 749

The feldspar crystals are sometimes arranged in rough augen. The
corundum occurs in grayish-blue crystals with an average size of 5
mm. and a maximum size of about 2cm. The corundum crystals are
tabular or prismatic in habit with the common forms: c jooort,
a {r120t, r {rorrt, m {2243t, and @ {8-8-16-3t. The most fre-
quent combination is acrn.

The corundum is often surrounded by a zone of feldspar, which
is nearly free from biotite. A fibrous mineral occasionally observed
proves to be sillimanite as tested in fragments. Muscovite is often
observed in thin, cleavable flakes. It does not appear to be an
alteration of the corundum. Thin sections show a very small
amount of zircon in minute prismatic crystals. The baddeleyite
is a black, submetallic mineral which is usually found between the
corundum and the feldspar. It occurs in rounded blebs and in
prismatic crystals not over 3 mm. in size and usually only about
Imm. in greatest dimension. The baddeleyite will be described
by the author in a forthcoming number of the American Journal
of Science.

Baddeleyite rather than zircon forms in this type of rock prob-
ably on account of the low silica percentage.

A rock sample weighing 243.6 grams was crushed, and after
sizing, the constituents were separated by means of Thoulét
solution. It was found that good separations could be made by
panning with the Thoulét solution. The following shows the
amounts of the various minerals and also the percentages by weight,
assuming the loss to be equally distributed among the minerals:

Grams Percentage
elals inate eerste scnc tecr ses £36010 O2n7
@orundumes vere os 67.53 30.9
BLO RICE MY usenys tee sess T2540 5S
iBaddelevite =n ssa oat O25

WOSS Hee tess eaceaie sue: 26.0
MOtale meres ect ee eee: QA 30 909.9

We. may assume the feldspar to be a eutectic of albite and
orthoclase. Vogt gives the eutectic ratio for these two minerals
as ab=58 per cent, or=42 per cent. We then have 36.4 per cent
albite and 26.3 percent orthoclase. The biotite is the only mineral

750° ; AUSTIN F. ROGERS

which does not have a fixed chemical composition. We may,
however, assume the following percentages which are average
values for biotite SiO,=37 per cent, Al,O,=16 per.cent, Fe,O,=6
per cent, FeO=15 per cent, MgO=12 per cent, K,0=10 per cent,
H,O=4 per cent.

The recalculated chemical analysis of the rock given is as follows:

Orthoclase| Albite |Corundum| Biotite Baddeleyite Total

SiQaee ney ere alee 17.0 25.0 ee 2aT 44.1
NEO yee sie area ern oe 4.8 Giga 30.9 0.9 43-7
Hes © yeep pare tera pee Sal. Sa eras O.3 0.3
Tie Oar patna neta 0.9 0.9
Vig © aes Per eG tte gee nen On7 Oni
(OE O Mirra ha Wal anne nea tiara ae Bisa Mae Seas
Na,0. SAG RRA IN Rea Gees 4.3 ee 4.3
KO ieee se aie cate 4.4 Me 0.6 5.0
AO Ne rs ei meant Pah: Sat ee 0.2 sieee 0.2
LO A Ge Rear TOI ae ae se nee raat Dee 0.5 0.5
26.2 36.4 30.9 Boo) 0.5 99.7

Chemically, this is a peculiar rock on account of the high alumina
and low silica content. It may be called a corundum-syenite. In
order to place this rock in the new quantitative classification it is
necessary to convert the percentage compositions of the oxids into
percentages of the standard minerals, which in this case are nearly
the same as the actual minerals. In other words, the mode and the
norm agree closely, biotite being practically the only critical mineral.
The calculated norm of the rock is shown in table on p. 751.

All the potash goes into the orthoclase molecule, all the ferric
iron and an equivalent amount of the ferrous iron go to make the
magnetite molecule. The remaining ferrous oxid goes with all
the magnesia to form the hypersthene molecule which requires an
equivalent amount of silica. The silica remaining after deducting
that required for the orthoclase, hypersthene, and zircon would
naturally go into the albite molecule, but it is found that there is too
much soda for this amount of silica so that the silica and soda must
be distributed between the albite and nephelite according to the

equations :*
x+ y=molecules of Na.O
6x-+ 2y=available SiO.

* Quant. Class. of Igneous Rocks, 194 (1903).

ON CORUNDUM-SYENITE FROM MONTANA 751

in which « is the albite molecule and y the nephelite molecule. The
remaining alumina goes into the corundum molecule.

Or Mt Hy Z Ab Ne (e
SiO; =44.1 19.1 ae Tey, 0.2 22). TO 5G
Al,O; =43.7 a7) Hike side Stelle 6.3 0.8 212
Fe,0;= 0.3 eat 0.3 fee Des Say SHG Bane
FeO = 0.9 one O.1 0.8 oy if
MgO = 0.7 at as 54) - ae
Na,O= 4.3 eke yee a 3.8 Ons
K,0 = 5.0 5.0 ne oe
ZrO, = 0.5 al 0.5
29.5 0.4 2 0.7 32.2 2.3 Be2
Orthoclase = 20.5 F
Albite = 32.2
Nephelite Si PINE nal 6, ,
Corundum =e aT 2 Salic
Zircon =a ong. 12,
Magnetite = Onan Vi
Hypersthene = 3.2 P Senne
Total = 90.5

The classification of the rock according to the new quantitative
system is as follows:

= aoe sa Class I, Persalone
ag = a ; she : Subclass IT, Persalone
= =359< : Order 5, Perfelic
aes | = “2 =e Rang 1, Peralkalic
aa =e — Subrang 3, Sodipotassic

The magmatic name of this subrang is uralose and the magmatic
symbol I’, 5, 1, 3. Only two rocks have previously been assigned?
to uralose, a corundum-syenite and a corundum-pegmatite, both
from the Urals.

t Washington, Professional Paper, U.S.G.S., No. 14, 217 (1903).

A DRAWING-BOARD WITH REVOLVING DISK FOR
STEREOGRAPHIC PROJECTION

ALBERT JOHANNSEN
The University of Chicago

Professor Wiilfing recently showed the writer a wall chart for
stereographic projection which he has since described.t_ It consists
of a ground glass plate back of which is pivoted a 70 cm. Wulff net
which is made of pasteboard and projects beyond the glass cover
so that it may be turned to any desired position. The advantages
of using the Wiilfing chart were so apparent that the writer has
constructed a drawing-board, for the individual use of students, on
a somewhat similar plan but combining with the Wulff net a half-
net with the north pole at the center. The construction is simple
and the board inexpensive.

In making stereographic projections by ordinary methods, one
must either work out his own dimensions, use a Penfield protractor,
or a net like that of Fedorow or of Wulff. Transparent nets are an
improvement over Penfield’s method, although one must always
carefully center the net for each measurement. With the drawing-
board here described, the net is revolved instead of the paper and
no centering is necessary.

The board was constructed from an ordinary drawing-board,
332435 cm. in size. It was placed on a lathe and a recess, 22 cm.
in diameter (D-J in the illustration), was turned out halfway
through the board which was 2 cm. thick. <A further slight cut
(H) was made to reduce friction when the disk is rotated, leaving
only the bearing shown at F-F. A 2 cm. hole was turned entirely
through the board (P-G). To keep the dial disk (B-C) perfectly
flat, it was made from a piece of three-ply, built-up pyrography
board, such as is sold in all art stores. This disk, also, was accu-

™E. A. Wiilfing, ‘“Wandtafeln fiir stereographische Projektion,” Centralbl. f. Min.,
Geol., u. Pal. (1911), 273-75.

7°2

DRAWING-BOARD FOR STEREOGRAPHIC PROJECTION 753

DD a9 ee = “
LY iS 3 V Y BSS AMX AQ AQ qh
ee K GY Se

YY Ge
Z

754 ALBERT JOHANNSEN

rately turned on the lathe and has a diameter of 21.8 cm., which
leaves, when inserted in the recess prepared for it, a very slight
margin for expansion. In the exact center a 2 cm. hole was turned

and into this the plug P-G was glued. P is a copper rivet set in -

the top of the plug to serve as a compass center. K is a metal
washer and L-L a wooden knob held on the plug G only by friction.
This permits its removal in case the dial should ever bind and need
trimming down. M-M are knobs, one of which is glued to each
corner of the board. They serve as feet to keep the button L from
touching when the board is placed on a flat surface. The plug P-G
fits snugly into the drawing-board and the dial will readily remain
in any position to which it is turned. |

The net B-C in the accompanying figure is shown divided only
into parts of to degrees each. Actually the section B was made by
gluing half a Wulff net to the top of the dial disk. The mathe-
matical center is located by a very small pit in the top of the plug
P. A further guide to centering the net is a scratch circle described
upon the wooden disk and having a diameter of 2 mm. more than
the Wulff net. The section C of the dial is used to measure dis-
tances on horizontal small circles and vertical great circles. It was
made on a sheet of cardboard by drawing circles from the stereo-
graphically projected lines of the Wulff net. These also, as well
as the projected great circles which appear as radii, are drawn 2
degrees apart although they are shown ro degrees apart in the figure.
Upon the drawing-board itself the N-S and E-W lines were drawn
parallel to the sides of the board.

Cutting the net in half occasionally makes it necessary to com-
plete a vertical small circle in two lines. The curves of the right-
hand net (C) might have been drawn, say in red, over a complete
Wulff net, but the confusion resulting would probably cause more
inconvenience than the present necessity of occasionally drawing a
vertical small circle in two operations. In most cases where such
circles are used, the degree divisions on the equator are a sufficient
substitute for the half-net cut off. Perhaps if the lines of every
fifth vertical small circle were extended over the upper half of the
right-hand net, it would be a convenience.

« Zeitschr. f. Kryst., XXXVI (1902), 14-18.

DRAWING-BOARD FOR STEREOGRAPHIC PROJECTION 755

The process of drawing is extremely simple. A sheet of tracing
paper is fastened to the board (A-A) by means of thumb tacks and
all angles and distances are measured directly by rotating the net
into the desired positions. Since in stereographic projections all
circles and angles appear in true proportions, such a drawing-board
should find extensive use for map drawing as well as for crystal
projection.

REVIEWS

‘‘Middle Cambrian Merostomata.”’ By CHARLES D. WALCOTT.
Cambrian Geology and Paleontology, Il, No. 2.

‘‘Middle Cambrian Holothurians and Medusae.”’ By CHartes D.
Watcorr. Ibid., No. 3.

“Middle Cambrian Annelids.””’ By Cuartes D. Watcortt. Ibid.,
No. 5.

In these three papers Dr. Walcott has described a portion of one of
the most remarkable extinct faunas which any paleontologist has ever
brought to light. The fossils occur in the Burgess shale of the Stephen
formation, in British Columbia. Their manner of preservation is un-
usual, the organisms being pressed flat, the soft-bodied Holothurians
Medusae, and Annelids being represented only by thin films which
fortunately are darker than the shale and are usually shiny. The
internal structures are often preserved in glistening, silvery surfaces,
even to the fine details. The illustrations of the fossils have been
beautifully executed by an ingenious process of photography by reflected
light, the photographs being reproduced upon heliotype and half-tone
plates.

The Merostomata contained in this remarkable fauna are referred
to two new genera, Sidneyia and Amiella, both included in the order
Eurypterida, and each made the type of a new family. Each genus is
represented by a single species. Sidneyia imexpectans is a remarkable
type, such.as might be expected in an Ordovician rather than in a Middle
Cambrian fauna, it is much the commoner of the two and some of the
specimens are preserved in such a perfect condition that the structural
details of the ventral appendages, even of the branchiae, can be worked
out. Amiella ornata is represented in the collection by a single broken
specimen, and is consequently much less perfectly understood.

The commonest of the Holothurians, Eldonia ludwigi, a new genus
and species, is a peculiar, free-swimming type, with an umbrella-shaped,
medusa-like body, growing to a size of 12 cm. in diameter. The spiral
alimentary canal, the oral aperture and tentacles, and the water-
vascular system are well shown in many of the specimens. Other Holo-
thurians with more or less elongate, cylindrical bodies, having more the
form of living members of the class, are represented by the new genera
Laggania, Louisella, and Mackenzia. The Medusae are much less

750

REVIEWS 757

common than the Holothurians; a single new genus and species, Pey-
tota nathorstt, is described, its condition of preservation being identical
with that of the Holothurians.

Heretofore the existence of Annelids at the time of deposition of
very ancient sediments has been inferred from the presence of certain
more or less obscure burrows and trails, but here in the Burgess shale
Walcott has been able to recognize eleven genera of these organisms, so
perfectly preserved that not only the segmentation of the body but the
most delicate appendages can be recognized. The genera are of course
all new, and they belong to widely separated families, indicating a
remarkable degree of differentiation at this very early period.

Descriptions of the numerous Phyllopod crustaceans which are said
to be associated with the organisms discussed in the three papers here
noticed, have not yet been published. They will doubtless be made
the subject of another paper in this same volume of Cambrian Geology
and Paleontology. S. W.

Seismic History of the Southern Andes (Historia sismica de los
Andes Meridionales. POR EL CONDE FERNANDO DE MONTES-
SUS DE BALLORE, director del Servicio Sismdlojico de Chile.
Primera Parte. Santiago de Chile, 1911).

As is well known, one of the most unstable regions upon the globe is
represented by the great Cordilleran backbone of South America. Yet
until quite recently little has been undertaken on scientific lines within
that vast region, and its seismic history has been a closed book. When,
as a consequence of the object-lesson furnished by the late Valparaiso
earthquake, the Republic of Chile established a modern seismological
service, it very wisely decided to call to its directorship one of the fore-
most of living authorities upon earthquake phenomena. Already famil-
iar with the Spanish language from years of residence in Central America,
and an experienced compiler of seismic maps and catalogues, it was
inevitable that the Count de Montessus would not long delay in exploit-
ing the rich mine of seismic facts so long buried in local historical docu-
ments. This agreeable task the new director has undertaken, and the
wealth of the material has proved even greater than was supposed, so
that it will fill several volumes. The first of these has just appeared and
is entitled “Seismic History of the Southern Andes” (Historia sismica
de los Andes Meridionales. Por el Conde Fernando de Montessus de
Ballore, director del Servicio Sismélojico de Chile. Primera Parte.
Santiago de Chile, torr).

758 REVIEWS

This seismic history covers the period from 1810 to 1905. The
second volume, which is now in press, will treat the much more inter-
esting earthquake of southern Peru, Bolivia, and northern Chile. Seis-
mologists will rather generally regret that it was necessary to print the

results in the Spanish language.
WH Ee

“The Production of Phosphate Rock in 1g1o.” By F. B. VAN
Horn. Advance chapter from Mineral Resources of the United
States for 1910, U.S. Geol. Survey, Washington, tg1t.

The total production of phosphate rock in 1910 showed an increase
of a little over 10 per cent over the 1909 production. The increase
came notably from Florida, with small increase from Tennessee and the
western fields, and a drop in production from North Carolina. A drop
of fifty-one cents per ton in the average price brought the increase in
value down to a little over 1 per cent. Florida is as before by far the
largest producer, giving 77.9 per cent of the total for 1910. A short
chapter on methods of mining phosphate rock in the various fields is

inserted.
A. D. B.

“The Manufacture of Coke in 1g1o.” By Epwarp W. PARKER.
Advance chapter from Mineral Resources of the United States
for 1910, U.S. Geol. Survey, Washington, tort.

The coke output of the United States in 1910 broke the record of
1907 by nearly a million tons but by no means reached the 1907 record
for value. Compared with 1909 the amount increased 6.1 per cent
and the value 10.9 per cent. Illinois rose from fifth to fourth rank
owing to the installation of ovens at Joliet by the United States Steel
Corporation, but in general the rank of producing states changed little.
In 1910, 17.12 per cent of the output was from by-products ovens,
against 15.94 per cent in 1909.

In spite of the increased production and higher price of coke, 1910
was not a satisfactory year from the producer’s standpoint. The
increased value of the coal charged into the ovens more than offset the
increase in price of coke. A downward tendency in price held through-
out, with the result that before the end of the year some manufacturers
were running at a loss.

A. D. B.

VDE TO 1 OLUOME X 1X

Adams, James Henry. The Geology of the Whatatutu Subdivision,
Raukumara Division, Poverty Bay. Review by E.R.L. .

Age and Relations of the Little Falls Dolomite (Calciferous) of the
Mohawk Valley. By E. O. Ulrich and H. P. Cushing. Review
bye Eee Rae, :

Age of the Type Exposures of he Tearrette Formation: The. By
Edward W. Berry

Agency of Manganese in the Smamunel Alteration ond Seconda
Enrichment of Gold Deposits, The. By William H. Emmons

Arnold, Ralph. Paleontology of the Coalinga District, Fresno and
Kings Counties, California. Review by E. R. L.

Arschinow, Wladimir. Ueber die Verwendung einer Ginehalbeupel zu
quantitativen optischen Untersuchungen am _ Polarisationsmi-
kroskope. Review by Albert Johannsen

Artesian Waters of Argentina. Editorial by B. W.

Ashley, George H. Outline Introduction to the Mineral Resources er
Tennessee. Review by E. R. L.

Atwood, Wallace W. Physiographic Studies in the Sam quan mictict
of Colorado : : : ; ; ; ;

Axinit von Californien. By W. T. Schaller. Author’s abstract

Bain, H. Foster. Samuel Calvin ; : :

Barr, James A. Testing for Metallurgical Praarkees: fRevicn by
WEE. EE:

Barringer, D. M. Meteor Grater (Pomaery Called Coon Miouneain
or Coon Butte) in Northern Central Arizona. Review by E. R. L.

Barrows, Harlan H., and Eliot Blackwelder. Elements of Geology.
Review by R. T. c: :

Bastin, Edson S. Geology of the Begmiatites and Neconied Rocks i
Maine. Review by Albert Johannsen

Bendrat, T. A. Geologic and Petrographic Notes on ine Region about
Caicara, Venezuela . , : : : : : E 5

Benedicks, Carl, and Olof Tenow. A Simple Method for Photograph-
ing Large Preparations in Polarized Light. Review by W. T.
Schaller . ; ; 5 :

Berkey, Charles P., ancl eese E. Hyde. fonemal Ice Structures Pre-
served in lneoncolidured Sands

Berry, Edward W. The Age of the Type aaeoanns of the lafayette
Formation : : : : : : ; :

Berthaut, Général. Topologie. Etude duterrain. Review by R. T.C.

759

PAGE

480

667
249

15
192
462
178
383

449
188

385

go
666
473
462

238

181
223

249
Q2

760 INDEX TO VOLUME XIX

Blackwelder, Eliot, and Harlan H. Barrows. Elements of Geology.
Review by R. T. C. :

Blatchley, Raymond S. Oil Recourecs of mnie with Srecial Reference
to the Area outside of the Southeastern Fields. Review by E. R. L.

Bowles, Oliver. Tables for the Determination of Common Rocks.
Review by Albert Johannsen

Bowman, H. L., and H. FE. Clark. On ie Sraneeure and Gopection
of the Ghandaeawur Meteoric Stone. Review by W. T. Schaller

Branner, John C. Syllabus of a Course of Lectures on Economic
Geology. Review by W. H. E.

Branson, E. B. Notes on the Osteology of the Skull of Pariotienue

Bretz, J. Harlen. The Terminal Moraine of the Puget Sound Glacier

Brock, R. W. Summary Report of the Geological Survey Branch of the
Department of Mines, Canada, for the Calendar Year 1909.
Review by E. R. L. : ; : : : : , :

Buckman, S. S., Editor. Yorkshire Type Ammonites. Part III.
Review by S. W. : F : : : ‘ : :

Buehler, H. A., and Others. Missouri Bureau of Geology and Mines.
Biennial Report of the State Geologist for the Years 1909 and
1910. Review by E. R. L. : ‘ : : : ;

Burchard, Ernest F., and Charles Butts. Iron Ores, Fuels, and Fluxes
of the Birmingham District, Alabama. Review by E. R. L.

Burroughs, Wilbur Greeley. The Unconformity between the Bedford
and Berea Formations of Northern Ohio

Butts, Charles, and Ernest F. Burchard. Iron Ores, Ta and Blnwes
of the Birmingham District, Alabama. Review by E. R. L.

Cairnes, D. D. Preliminary Memoir on the Lewes and Nordenskiold
Rivers Coal District, Yukon Territory. Review by W. A. T.

Calvin, Samuel. By H. Foster Bain

The Iowan Drift ; . : : 5 :

Calvin, Samuel, and Others. Iowa Geological Survey, Vol. XX. Annual
Report, 1909, with Accompanying Papers. Review by E. R. L.

Cambrian Conglomerate of Ripton in Vermont, The. By T. Nelson
Dale. Review by Albert Johannsen .

Camera-lucida Attachment for the Goniometer, A. Be G. 106 Here
Smith. Review by W. T. Schaller : :

Cenozoic Mammal Horizons of Western North Americas By Henry
Fairfield Osborn, with Faunal Lists of the Tertiary Mammalia of
the West by William Diller Matthew. Review by E. R. L.

Certain Phases of Glacial Erosion. By Thomas C. Chamberlin and
Rollin T. Chamberlin ; : : : : : z

Chamberlin, Rollin Thomas. Notes on Explosive Mine Gases and
Dusts with Special Reference to Explosions in the Monongah,
Darr, and Naomi Coal Mines. Review by E. R. L.

PAGE
473
666
181
181
281
135
161
384

666

193

INDEX TO VOLUME XIX

Chamberlin, T. C. The Bearings of Radioactivity on Geology . :
Chamberlin, Thomas C. and Rollin T. Certain Phases of Glacial
Erosion .

Clapp, Frederick G. A Bropored: Ghesacieen 6 Petolenmn and
Natural Gas Fields Based on Structure. Review by E. R. L.
Clark, William Bullock. Maryland Geological Survey, Vol. VIII, 1909.

Review by E. R. L. ;
Cleland, Herdman F. The ores and Giuieeay of ine Middle
Devonic of Wisconsin. Review by S. W. ; 4 :
Climate and Physical Conditions of the Keewatin. By A. P. Coleman
Coleman, A. P. Climate and Physical Conditions of the Keewatin
Coming of Evolution, The: the Story of a Great Evolution. By John
W. Judd. Review by W. H. H. ’ : :
Composition of Some Minnesota Rocks and Ninna shes By;
Frank F. Grout. Review by Albert Johannsen . : : :
Cortége filonien des péridotites de la Nouvelle Calédonie, Le. By A.
Lacroix. Review by F. C. Calkins . :
Corundum-Syenite (Uralose) from Montana, On. By Austin F. Rogers
Couyat, J. Les roches sodiques du désert arabique. Review by F. C.
Calkins) <7
Cretaceous and T Bes nOErations of Nicer nanan Malcoe ral
Eastern Montana, The. By A. G. Leonard : :
Crider, Albert F. Mississippi State Geological Survey, 1907. Review
by E. R. L.
Cushing, H. P., and E. O. iia Age cut Relations ai ihe Little Falls
Dolomite (Calsterous) of the Mohawk Valley. Review by E.R.L.

Dakota-Permian Contact in Kansas, The. By F. C. Greene. Review
by E. R. L. : : , : ;

Dale, T. Nelson. The Cambrian Conglomerate of Ripton in Vermont.
Review by Albert Johannsen :

Daly, Reginald A. Magmatic Iniferentiationli in Hama ;

De Ballore, Conde Fernando de Montessus. Seismic History of ie
Southern Andes (Historia sismica de los Andes Meridionales.)
Review by W. H. H. , ; : : : : ;

De Lapparent, Jacques. Les gabbros et diorites de Saint-Quay-
Portrieux et leur liaison avec les pegmatites qui les traversent.
Review by F. C. Calkins .

Derby, Orville A. Speculations renardine the Genes of the Diamond

Descriptive Mineralogy, with Especial Reference to the Occurrences and
Uses of Minerals. By Edward Henry Kraus. Review by W. H. E.

Differentiation of Keweenawan Diabases in the Vicinity of Lake
Nipigon, The. By E. S. Moore : ;

Dowling, D. B. The Edmonton Coal Field, Abert ‘TRagitey by
Vee Ae Ty.

281

429

477

762 INDEX TO VOLUME XIX

Drawing-Board with Revolving Disk for Stereographic Projection, A.
By Albert Johannsen

Duffield, T. A Review of Mining (Opadifions in me State a South
Australia during the Half-Year Ended December 31, 1910. Re-
view by A. D. B. ; ; :

Duparc, L., and G. Pamphil. Sur lissite, une nouvelle roche filonienne
dans la dunite. Review by F. C. Calkins .

— Duparc, L., and M. Wunder. Sur les Serpentines du erebet! Salata
(Oural du Nord). Review by F. C. Calkins

Duparc, Wunder, and Sabot. Les minéraux des pegmatites des environs
d’Antsirabé 4 Madagascar. Review by W. R. Schaller

Economic Theory with Special Reference to the United States. By
Heinrich Ries. Review by W. H. E. :

Editorial: Artesian Waters of Argentina. By B. W.

Editorial: The Seeding of Worlds. By T. C. C.

Editorial, sByel Cac: : : : ; : : :

Edmonton Coal Field, Alberta, The. By D. B. Dowling. Review by
WicAlnet:

Eisenmeteorit von NMuomionalwees | im vardliehsten iSchweden Weber
einen. By A. G. Hégbom. Review by W. T. Schaller :

Elemente der Gesteinslehre. By H. Rosenbusch. Review by Edward
B. Mathews :

Elements of Geology. By Eliot Blver welder and Harlan H. Barrows!
Review by R. T. C. ;

Emmons, William H. The Neen of Manganese in the Superdeel
Alteration and Secondary Enrichment of Gold Deposits

Erlauterungen zur geologischen und mineralogischen Karte des 6st-
lichen Aaremassivs von Disentis bis zum Spannort. By Joh.
Koenigsberger. Review by Albert Johannsen

Erythrosuchus, Vertreter der neuen Reptilordnung Beneoeiae Weped
By F. von Huene. Review by S. W. Williston . :

Evolution of Limestone and Dolomite. I, The. By Edward Steidt-
mann . : : :

Evolution of isimetone ana Dolomite! II, The. By Edward Steidt-
mann

Explosive Mine (Gases ane Duets wae Special Relerente 1B Explosions
in the Monongah, Darr, and Naomi Coal Mines, Notes on. By
Rollin Thomas Chamberlin. Review by E. R. L.

Farrington, Oliver Cummings. Meteorite Studies, III. Review by
E. R. Lloyd ; :
Focus of Postglacial Uplift Nowh ot the Cer ibalkes, The. By J. W.
Spencer . : Pia ee ; ; :
Forbes, William T. M. A Geological Route through Central Asia Minor

PAGE

752

479

284

INDEX TO VOLUME XIX

Fossils and Stratigraphy of the Middle Devonic of Wisconsin, The.
By Herdman F. Cleland. Review by S. W.

Further Data on the Stratigraphic Position of the Lance Romnation
(““Ceratops Beds’’). By F. H. Knowlton .

Gabbros et diorites de Saint-Quay-Portrieux et leur liaison avec les
pegmatites qui les traversent, Les. By Jacques de Lapparent.
Review by F. C. Calkins . ;

Geijer, Per A. Geology of the Kiruna Diciick (2). Igneous Rocks
and Iron Ore of Kiirunavaara Luossovaara and Tualluvaara.
Review by W. H. E. : :

Genera of Mississippian Loop-bearing Beelvopoder By Stuart Weller

Genus Syringopleura Schuchert, On the. By George H. Girty .

Geologic and Petrographic Notes on the Region about Caicara, Vene-
zuela. By T. A. Bendrat : : ;

Geological and Archaeological Notes on Orang By J. P. Johnson.
Review by E. R. L. :

Geological Route through Central hein Manor: “a By William T. M.
Forbes

Geological Survey peanen of ite Department of Mines, Canis fon the
Calendar Year 1909, Summary Report of the. By R. W. Brock.
Review by E. R. L. : : 5 : :

Geological Survey of Georgia. Bull. No. 23, Mineral Resources. By
S. W. McCallie. Review by E. R. L.

Geological Survey of New Jersey, 1909, Annual Report of the State
Geologist. By Henry B. Kiimmel. Review by E. R. L.

Geological Survey of Western Australia for the Year 1909, Annual
Report of the. By A. Gibb Maitland. Review by E. R. L.

Geology and Ore Deposits of Republic Mining District. By Joseph B.
Umpleby. Review by R. T. C. :

Geology and Ore Deposits of the West Pilbara Goldfield, The. By H. P.
Woodward. Review by A. D. B. : : ‘

Geology of Building Stones, The. By J. Allen Hone! Review by
Albert Johannsen ; : ; : ;

Geology of New Zealand, The. By James Park. - Review by R. T. C.

Geology of the Kiruna District (2). Igneous Rocks and Iron Ore of
Kiirunavaara Luossovaara and Tualluvaara. By Per A. Geijer.
Review by W. H. E. ; : : : :

Geology of the Nipigon Basin, Grin. By A. W. G. Wilson. Review
byaWe Ace. :

Geology of the Pegmatites rat Aesociated Rocks of Maines By Edson
S. Bastin. Review by Albert Johannsen

Geology of the Whatatutu Subdivision, Raukumara Disicvon, poverty
Bay, The. By James Henry Adams. Review by E. R. L.

Girty, George H. On the Genus Syringopleura Schuchert

384
IQl
383
382

93
478
465

gl
476
477
462

480
548

764 INDEX TO VOLUME XIX

Girty, George H., C. H. Gordon, and David White. The Wichita
Formation of Norther Texas : f

Gordon, C. H., George H. Girty, and aaa White. The Wichita
Formation of Northern Texas :

Gordon, Charles H., Waldemar Lindgren, and sways C: Grton The
Ore Deposits af New Mexico. Review by W. H. E. :

Grabau, A. W., and W. H. Sherzer. The Monroe Formation of South
ern Michigan and Adjoining Regions. Review by S. W. .

Grabau, Amadeus W., and Hervey Woodburn Shimer. North American
Index Fossils: Tnvertebiats: Review by S. W.

Grabham, G. W. An Improved Form of Petrological Microscope:
with Some General Notes on the Illumination of Microscopic
Objects. Review by W. T. Schaller .

Grandjean, F. Sur un mésure du laminage des sediments (Gilets oh
schistes) par celui de leurs cristaux clastiques de tourmaline.
Review by F. C. Calkins . :

Graton, Louis C., Waldemar Lindgren, and Charles H. Gaiden: The
Ore Deposits of New Mexico. Review by W. H. E.

Gravel as a Resistant Rock. By John Lyon Rich .

Grayson, H. J. Modern Improvements in Rock Section Cutine
Apparatus. Review by Albert Johannsen . : : ;

Greene, F. C. The Dakota-Permian Contact in Kansas. Review by

Groth-Jackson. The Optical Properties of Crystals. Review by
Albert Johannsen

Grout, Frank F. The Composition of some oMinnesoes ROLES and
Minerals. Review by Albert Johannsen

Gypsum Deposits of New York. By D. H. Newland and Eenny,
Leighton. Review by E. R. L. ; : :

High Terraces and Abandoned Valleys in Western Pennsylvania. By
Eugene Wesley Shaw

Hobbs, William H. Requisite Goniion: doe the Formation oi ee
Ramparts

Hégbom, A. G. eben einen imbenanseants von Meronionaluces im
nordlichsten Schweden. Review by W. T. Schaller .

Howe, J. Allen. The Geology of Building Stones. Review by Albert
Johannsen : :

Hubbard, George D. Tere Glacial Bomlders : : : :

Humphreys, Edwin W., and Alexis A. Julien. Local Decomposition
of Rock by the Corrosive Action of pre-Glacial Peat-Bogs .

Hyde, Jesse E. The Ripples of the Bedford and Berea Formations of
Central and Southern Ohio, with Notes on the Paleogeography of
that Epoch

PAGE

IIo
110
276
664

470

182

INDEX TO VOLUME XIX

Hyde, Jesse E., and Charles P. Berkey. Original Ice Structures. Pre-
served in Unconsolidated Sands

Intermediate (Quartz Monzonitic) Character of the Central and South-
ern Appalachian Granites. By Thomas L. Watson. Review by
Albert Johannsen

Iowa Geological Survey, Vol. XX, ieneal Resort 1909, with Aceon
panying Papers. By Samuel Calvin and Others. Review by
E.R. L: :

Iowan Drift, The. By Samuel Calin

Iron Ore Deposits along the Ottawa (Quebec Side) andl Gaunesn Reve
Report on the. By Fritz Cirkel. Review bya Reels:

Iron Ores, Fuels and Fluxes of the Birmingham District, Alabama.
By Ernest F. Burchard and Charles Butts. Review by E. R. L.

Joerg, W. The Tectonic Lines of the Northern Part of the North
American Cordillera. Review by R. T. C.

Johannsen, Albert. A Drawing-Board with Revolving Disk for Stereo:
graphic Projection

Petrographic Terms for Field Use ;

Johnson, J. P. Geological and Archaeological Notes on Oransa
Review by E. R. L. ; : : 3 : : : :

Jordan, David Starr (Editor). Leading American Men of Science.
Review by R. T. C. .

Judd, John W. The Coming of eeolacion: the Stony ofa Can Reva:
lution. Review by W. H. H. : : ; : ;

Julien, Alexis A., and Edwin W. Humphreys. Local Decomposition of
Rock by the Corrosive Action of pre-Glacial Peat-Bogs

Kindle, E. M. The Recurrence of Tropidoleptus carinatus in the
Chemung Fauna of Virginia

The Southerly Extension of the Oxcndies Seal in the Alieoheny
Region

Knowlton, F. H. Earner DEE on ihe Stadio ple Beetron of the
Lance Formation (‘‘Ceratops Beds’’)

Koenigsberger, Joh. Erlauterungen zur penlecichen tral inert
gischen Karte des 6stlichen Aaremassivs von Disentis bis zum
Spannort. Review by Albert Johannsen :

K6zu, S. Preliminary Notes on Some Igneous Rocks of joo Me

Preliminary Notes on Some Igneous Rocks of Japan. II.

Preliminary Notes on Some Igneous Rocks of Japan. III.

Preliminary Notes on Some Igneous Rocks of Japan. IV.

Kraus, Edward Henry. Descriptive Mineralogy, with Especial Reioe
ence to the Occurrences and Uses of Minerals. Review by W. H. E.

Kimmel, Henry B. Annual Report of the State Geologist, Geological
Survey of New Jersey, 1909. Review by E. R. L.

795

PAGE

766 INDEX TO VOLUME XIX

Lacroix, A. Le cortége filonien des péridotites de la Nouvelle Calé-
donie. Review by F. C. Calkins

Lamb, G. F. The Mississippian- Benner ivanian Uncontornicy cl the
Sharon Conglomerate

Large Glacial Bowlders. By Gooree D. Hue Bard

Leading American Men of Science. Edited by David Starr fonlant
Review by R. T. C.

Leighton, Henry, and D. H. Newland! Gusenia Deposits a NS
York. Review by E. R. L.

Leiss, C. Neues Mikroskop Modell VIb fiir yetallogranhische and
petrographische Studien. Review by Albert Johannsen ‘

Leonard, A. G. The Cretaceous and Tertiary Formations of Western
North Dakota and Eastern Montana

Lewis, Harmon. The Theory of Isostasy . , :

Lindgren, Waldemar, Louis C. Graton, and Charles H. Gardens The
Ore Deposits of New Mexico. Review by W. H. E.

Local Decomposition of Rock by the Corrosive Action of pre- Gaal
Peat-Bogs. By Edwin W. Humphreys and Alexis A. Julien

Magmatic Differentiation in Hawaii. By Reginald A. Daly :

Maitland, A. Gibb. Annual Report of the Geological Survey of Western
Australia for the Year 1909. Review by E. R. L.

‘““Manufacture of Coke in i910, The.” By Edward W. Pa
Review by A. D. B. é : : : : ‘

Maryland Geological Survey, Vol. Van tg0o9. By William Bullock
Clark. Review by E. R. L. : ; : :

McCallie, S. W. Geological Survey of (Ceormae Bull. No. 23, Mineral
Resources. Review by E. R. L. E

McInnes, William. Report on a Part of the Nownwest Peritoues
Drained by the Winisk and Attawapiskat Rivers. Review by
Hace ; : : : : : : :

Meteor Crater (Formerly Called Coon Mountain or Coon Butte) in

Northern Central Arizona. By D. M. Barringer. Review by .

E.R. L.

Meteorite Studies, III. By Oliver Cummings Farrington. Review

by E. R. Lloyd ; : Bier ss : :

Michel-Lévy, Albert. Les terrains primaires du Morvan et de la Loire.
Review by F. C. Calkins .

““Middle Cambrian Merostomata,” “ Middle Ganhran Eloloeanniane and
Medusae,” ‘‘ Middle Cambrian Annelids.”’ By Charles D. Wolcott.
Review by S. W. ;

Mineral Production of Virginia donne ihe C nlendae Wear aes! Annual
Report onthe. By Thomas Leonard Watson. Review by E.R. L.

Minéraux des pegmatites des environs d’Antsirabé a Madagascar, Les.
By Duparc, Wunder, and Sabot. Review by W. T. Schaller

382

182

INDEX TO VOLUME XIX

Mining Industry in North Carolina during 1907 with Special Report on
the Mineral Waters, The. By Joseph Hyde Pratt. Review by
pRe Gs ;

Mining Operations in the State of South Aneeralia dueine he Half-V ear
Ended December 31, 1910, A Review of. Issued by T. Duffield.
Review by A. D. B. : :

Mississippian-Pennsylvanian uncon termi and the Sharon Con-
glomerate, The. By G. F. Lamb : : : : :

Mississippi State Geological Survey, 1907. By Albert F. Crider.
Review by E. R. L. :

Missouri Bureau of Geology and Mines. Biennial Report of the State
Geologist for the Years 1909 and 1910. By H. A. Buehler and
Others. Review by E. R. L. ;

Modern Improvements in Rock Section Curing Aegoonciang: By Hear
Grayson. Review by Albert Johannsen

Monroe Formation of Southern Michigan and ajoinine Rerione! The.
By A. W. Grabau and W.-H. Sherzer. Review by S. W. .

Moore, E. S. The Differentiation of Keweenawan Diabases in the
Vicinity of Lake Nipigon .

Neues Mikroskop Modell VId fiir krystallographische und _petro-
graphische Studien. By C. Leiss. Review by Albert Johannsen
Newland, D. H., and Henry Leighton. Gypsum Deposits of New
York. Review by Re ¥
Nordenskjéld, Ivar. Der Pegmatit von Viterby. Review by Ww. “ES
Schaller . : :
North American mde Booeile: Invertebrates. By Amadeus W.
Grabau and Hervey Woodburn Shimer. Review by S. W. .
Notes on the Osteology of the Skull of Pariotichus. E. B. Branson
Northwest Territories Drained by the Winisk and Attawapiskat Rivers,
Report on a Part of the. By William McInnes. Review, by
leh Can Gs

Oil Resources of Illinois with Special Reference to the Area outside of
the Southeastern Fields. By Raymond S. Blatchley. Review by
E.R. L. ; :

Olenellus and Other Genes of the Mesonacidae: By Charles D. Wal-
cott. Review by S. W. =.

Optical Properties of Crystals, The. By Groth-Jackson. Review by
Albert Johannsen :

Ore Deposits of New Mier cor The. By Waldemar Lindgren, Louis
C. Graton, and Charles H. Gordon. Review by W. H. E.

Original Ice Structures Preserved in Unconsolidated Sands. By
Charles P. Berkey and Jesse E. Hyde.

767

PAGE

192

768 INDEX TO VOLUME XIX

Osborn, Henry Fairfield. Cenozoic Mammal Horizons of Western
North America, with Faunal Lists of the Tertiary Mammalia of
the West by William Diller Matthew. Review by E. R. L.. :

Osteology of the Skull of Pariotichus, Notes on the. By E. B. Branson

Outline Introduction to the Mineral Resources of Tennessee. By
George H. Ashley. Review by E. R. L. .

Paleontology of the Coalinga District, Fresno and Kings Counties,
California. By Ralph Armold. Review by E. R. L.

Pamphil, G., and L. Duparc. Sur l’issite, une nouvelle roche float
enne ‘ams la dunite. Review by F. C. Calkins .

Park, James. The Geology of New Zealand. Review by R. T. ic

Parker, Edward W. “The Manufacture of Coke in 1910.” Review
by A. D. B. :

Parkins, A. E. Valley Billings by Tatermniceent creme

Pegmatit von Ytterby, Der. By Ivar Nordenskjéld. Reee Ihe
W. T. Schaller : : : ; : : : i

Penck, Albrecht. Die Weltkarten-Konferenz in London im November,
1909. Review by R. T. C.

Perkins, G. H., and Others. Report of ine Vemnons State Groloniee
1909-1910. Review by E. R. L.

Petrographic Terms for Field Use. By Albert Johannces ‘

Petrographical Abstracts and Reviews. : : 181, a.

Petrological Microscope, An Improved Form oh with Some General
Notes on the Illumination of Microscopic Objects. By G. W.
Grabham. Review by W. T. Schaller

Physiographic Studies in the San Juan District oi Golorade. By
Wallace W. Atwood ; : ; :

Pleistocene Deposits in Warren County, lone The. By John Littlefield
Tilton. Review by R. T. C. :

Pogue, Joseph E. A Possible Limiting Effect at Grounce Water upon
Eolian Erosion

Possible Limiting Effect of Grown Water upon olan leeocion’ N
By Joseph E. Pogue

Practical Mineralogy Simplified. For Mining ‘Gudlavis, IMnners and
Prospectors. By Jesse Perry Rowe. Review by W. H. E.

Pratt, Joseph Hyde. The Mining Industry in North Carolina during
1907 with Special Report on the Mineral Waters. Review by
Heke: :

Preliminary Memoir on the iewes am Nondensl ior Re Coal
District, Yukon Territory. By D. D. Cairnes. Review by
Weve ale : : ; ; :

Preliminary Notes on Some Teneous Rocks of Japan. I. By S. Koézu

Preliminary Notes on Some Igneous Rocks of Japan. II. By S. Kozu

PAGE
95
135

383

192

464
gt

758
Diy]

187
189
667

317
462

TO2)-<

449

282
270
270

668

192

477
555
561

INDEX TO VOLUME XIX

Preliminary Notes on Some Igneous Rocks of Japan. III. ByS.Kézu 566
Preliminary Notes on Some Igneous Rocks of Japan. IV. ByS.Kézu 632
Preliminary Statement concerning a New System of Quaternary Lakes
in the Mississippi Basin. By Eugene Wesley Shaw 481
“Production of Phosphate Rock in 1910, The.” By F. B. Van Horn
Review by A. D. B. 758
Proposed Classification of Petroleum and Natural Gas Bields Based on
Structure, A. By Frederick G. Clapp. Review by E. R. L. 383
Prospecting inthe North. By Horace V. Winchell. Reviewby W.H.E. 100
Purdue, A. H. Recently Discovered Hot Springs in Arkansas . 272
The Slates of Arkansas, with a Bibliography of the Geology
of Arkansas by J. C. Branner. Review by E.R. L. . IQ!
Radioactivity on Geology, The Bearings of. By T. C. Chamberlin. 673
Rastall, R. H. The Skiddaw Granite and Its Metamorphism. Review
by Albert Johannsen 187
Recent Publications : 669
Recently Discovered Hot Ste in ab Anlcamenes By A. H. Purdue 272
Reconnaissance of the Book Cliffs Coal Field between Grand River,
Colorado, and Sunnyside, Utah. By G. B. Richardson. Review
by E. R. L. 95
Recurrence of abropidoleptus, Canation in the Ghemuge ann af
Virginia, The. By E. M. Kindle : 3 346
Reid, Harry Fielding. The Variations of Giieees XV. 83
The Variations of Glaciers. XVI. : 3 > ASA
Requisite Conditions for the Formation of Ice Ramparts. By William
H. Hobbs 157
Restoration of Seymouria Banlorensie Broil an Ameren @orylveane
By S. W. Williston . : S239
Reviews : ey 180, a6. ae 460, 76. 661, 756
Rich, John Lyon. leravel as a s Rectaicat Rock / » | AOD
Richardson, G. B. Reconnaissance of the Book Clifis Coal Field
between Grand River, Colorado, and Sunnyside, Utah. Review by
Re. : 95
Ries, Heinrich. Economic Theory mel Sneciall Referenee b ie
United States. Review by W. H. E. 90
Ripples of the Bedford and Berea Formations of Central and Southern
Ohio, with Notes on the Paleogeography of that Epoch, The.
By Jesse E. Hyde ; 5 ‘ : : 5) (G7
Roches sodiques du désert praGe: Les. By J. Couyat. Review by
BoG, Calkins” 463
Rogers, Austin F. On Commins vente (Grates) fon Monten 748

Rosenbusch, H. Elemente der Gesteinslehre. Review by Edward B.
Mathews

284

770 INDEX TO VOLUME XIX

Rounding of Sand Grains, Factors Influencing the. By Victor Ziegler
Rowe, Jesse Perry. Practical Mineralogy Simplified. For Mining
Students, Miners, and Prospectors. Review by W. H. E.

Schaller, W. T. Axinit von Californien. Author’s abstract
Schmerber, H. La sécurité dans les mines. Review by R. T. C.
Sécurité dans les mines, La. By H. Schmerber. Review by R. T. C.
Seeding of Worlds, The. Editorial by T. C. C.

Seismic History of the Southern Andes (Historia Sismica ae 1s Andes
Meridionales.) Por el Conde Fernando de Montessus de Ballore.
Review by W. H. H. : :

Serpentines du Krebet-Salatim (Oural de Nord), ‘Sur ies By L.
Duparc and M. Wunder. Review by F. C. Calkins .

Shaw, Eugene Wesley. High Terraces and Abandoned Valleys in
Western Pennsylvania

Preliminary Statement concerning a New System of @uater:
nary Lakes in the Mississippi Basin . §

Sherzer, W. H., and A. W. Grabau. The Monroe Hore tion of South:
ern Michigan and Adjoining Regions. Review by S. W. :

Shimer, Hervey Woodburn, and Amadeus W. Grabau. North Ameri-
can Index Fossils: Invertebrates. Review by S. W.

Simple Method for Photographing Large Preparations in Polarized Light,
A. By Carl Benedicks and Olof Tenow. Review by W. T. Schaller

Skeats, Ernest W. The Volcanic Rocks of Victoria. Review by Albert .

Johannsen ;
Skiddaw Granite and Its Me tamoriicn The. By R. H. Rastall.
Review by Albert Johannsen
Slates of Arkansas, The. By A. H. Batdue: vith a Bibkoorphy of the
Geology of Arkansas by J. C. Branner. Review by E. R. L.
Smith, G. F. Herbert. A Camera-lucida Attachment for the Gonio-
meter. Review by W. T. Schaller
Southerly Extension of the Onondaga Sea in the Allesheny Report The.
By E. M. Kindle ;
Speculations regarding the Genego of ile Diamond: By Orie A
Derby : i : : ; 3 : : ‘
Spencer, J. W. The Focus of Postglacial Uplift North of the Great
Lakes :
Steidtmann, Edward. The Evolution of Limestone and Delonte: I.
The Evolution of Limestone and Dolomite. II. . ’
Structure and Composition of the Chandakapur Meteoric Stone, On
the. By H. L. Bowman and H. E. Clarke. Review by W. T.
Schaller . : :
Sur l’issite, une nouvelle roche omen dine 1 dunes By L. Duparce
and G. Pamphil. Review by F. C. Calkins

PAGE

645

668
188

92
175
757
464
140
481
664
47°
181
466
187
IQI
188

97
627

323
392

I8t

464

INDEX TO VOLUME XIX

Syllabus of a Course of Lectures on Economic Geology. By John C.
Branner. Review by W. H. E.

Tables for the Determination of Common Rocks. By Oliver Bowles.
Review by Albert Johannsen

Tectonic Lines of the Northern Part of the North Ameren Cordillers
The. By W. Joerg. Review by R. T. C. : :

Terminal Moraine of the Puget Sound Glacier, The. By J. Harlen Bretz

Terrains primaires du Morvan et de la Loire, Les. By Albert Michel-
Lévy. Review by F. C. Calkins : : ; :

Terrestrial Deposits of Owens Valley, C nliferniat By A. C. Trowbridge

Testing for Metallurgical Processes. By James A. Barr. Review by
Wiese: :

Theory of Isostasy, The. By Hon Degas :

Tilton, John Littlefield. The Pleistocene Deposits in Warten County)
Iowa. Review by R. T. C. : : : : : :

Topologie. Etude du terrain. Par le Général Berthaut. Review by
Re G: :

Traverse through the Souther [Pare of the NGrihwrest Terstones from
La Seul to Cat Lake in 1902, Report on. By Alfred G. Wilson.
Review by W. C. C.

Trowbridge, A. C. The Terrestrial Menosits of Owens Valley: G@alvarai

Ulrich, E. O., and H. P. Cushing. Age and Relations of the Little Falls
Dolomite (Calciferous) of the Mohawk Valley. Review by E. R.L.

Umpleby, Joseph B. Geology and Ore Deposits of Republic Mining
District. Review by R. T. C.

Un mésure du laminage des Gaments (calenites et aus) par asl a
leurs cristaux clastiques de tourmaline, Sur. By F. Grandjean.
Review by F. C. Calkins .

Unconformity between the Bedford and Been Homnacions a Norton
Ohio, The. By Wilbur Greeley Burroughs :

Use of “‘Ophitic”’ and Related Terms in Petrography. Be Alewandes
N. Winchell. Review by Albert Johannsen

Valley Filling by Intermittent Streams. By A. E. Parkins .

Van Horn, F. B. ‘‘The Production of Phosphate Rock in rogro.”’
Review by A. D. B. ; : ; : : f

Variations of Glaciers, The. XV. By Harry Fielding Reid

Variations of Glaciers, The. XVI. By Harry Fielding Reid . ;

Vermont State Geologist, 1909-1910, Report of the. By G. H. Perkins
and Others. Review by E. R. L.

Verwendung einer Glashalbkugel zu quantitativen fonueeten Unter
suchungen am Polarisationsmikroskope, Ueber die. By Wladimir
Arschinow. Review by Albert Johannsen .

666
706

667

772 ' INDEX TO VOLUME XIX

Volcanic Rocks of Victoria, The. By Ernest W. Skeats. Review by
Albert Johannsen

von Huene, F. Ueber Ery amoaucties, Were der neuen Renal
ordnung Pelycosimia. Review by S. W. Williston

Walcott, Charles D. Olenellus and Other Genera of the Mesonacidae.
Review by S. W. 2

“Middle Cambrian ivieroetarantne a ‘Middle C Suan Holothus
rians and Medusae,”’ ““ Middle Cambrian Annelids.” Review by S. W.

Watson, Thomas Leonard. Annual Report on the Mineral Production
of Virginia during the Calendar Year 1to08. Review by E. R. L.

Intermediate (Quartz Monzonitic) Character of the Central
and Southern Appalachian Granites. Review by Albert Johann-
sen : : : : : : 5 , 3

Weller, Stuart. Genera of Mississippian Loop-bearing Brachiopoda .

Weltkarten-Konferenz in London im November, 1909, Die. By
Albrecht Penck. Review by R. T. C. : : :

. White, David, C. H. Gordon, and George H. Gira The Wichita
Formation of Northern Texas : ; :

Wichita Formation of Northern Texas, The. By C€. H. Gordon,
George H. Girty, and David White

Williston, S. W. Restoration of Seymouria Baylorenss Broil an
American Cotylosaur

The Wing-Finger of Pterodactys, oan Rectarrion of Ngee
saurus

Wilson, Alfred G. “Report on Stray erse ironed rhe! Southern Part af
the Northwest Territories from Lac Seul to Cat Lake in 1qo2.
Review by H. C. C.. : : ‘

Wilson, A. W. G. Geology of the Ninieon Sct Ontario. * Review by
WavAG an : : ; . ; : : :

Winchell, Alexander N. Use of “Ophitic’’ and Related Terms in
Petrography. Review by Albert Johannsen

Winchell, Horace V. Prospecting in the North. Review ie W. H. E.

Wing-Finger of Pterodactyls, with Restoration of Nyctosaurus, The.
By S. W. Williston .

Woodward, H. P. The Geology and Ore Meno a the West Pilbara
Goldfield. Review by A. D. B. ;

Wunder, M., and L. Duparc. Sur les Serpentines an ieee ante
(Oural du Nord). Review by F. C. Calkins

Yorkshire Type Ammonites. Part III. Edited by S. S. Buckman.
Review by S. W.

Ziegler, Victor. Factors Influencing the Rounding of Sand Grains

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