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Ab Taleh

Ler N AL Or GEOLOGY

A Semi-Quarterly Magazine of Geology and
Relateds: Scrences

EpIToRS
T. C. CHAMBERLIN, zz General Charge

R. D. SALISBURY Rk. A. BE. PENROSE, Jr:

Geographic Geology Liconomic Geology
J. P. IDDINGS CR. VAN HIS

Petrology Pre-Cambrian Geology
STUART WELLER We Ee HOLMES

Paleontologic Geology Anthropic Geology

ASSOCIATE EDITORS

SIR ARCHIBALD GEIKIE O. A. DERBY

Great Britain Brazil
H. ROSENBUSCH G. K. GILBERT

Germany Washington, D. C.
CHARLES BARROIS H. S. WILLIAMS

France Vale University
ALBRECHT PENCK JOSEPH LE CONTE

Austria University of California
HANS REUSCH Cs IDs WAILICOI I

Norway U.S. Geological Survey
GERARD DE GEER J. C. BRANNER

Sweden Stanford University
GEORGE M. DAWSON iE Gy RUSSHE

Canada University of Michigan

WILLIAM B. CLARK, Johns Hopkins University

fF isonian Insitaygs
(250422

VOEUMEE V Ill \

Sonal Muses

GHICAGO
The Wnibversity of Chicago Press

19g00

PRINTED BY
The University of Chicago Press
CHICAGO

COMMPINGES OF WA OTOMIR GUA s

NUMBER I.

PAGE

SUGGESTIONS REGARDING THE CLASSIFICATION OF THE IGNEOUS ROCKS.
William H. Hobbs = = - > - = - - - - I
DENTITION OF SOME DEVONIAN FisHES. C. R. Eastman - - - - 32

ANCIENT ALPINE GLACIERS OF THE SIERRA CostA MOUNTAINS IN CALI-
FORNIA. Oscar H. Hershey = > = = : - = - 42

AN ATrempr TO TEST THE NEBULAR HYPOTHESIS BY THE RELATIONS OF
Masses AND MoMENTA. T. C. Chamberlin - = - : 2 58
EDITORIAL - - - - = - - = - - + = - 74

Reviews: The Diuturnal Theory of theEarth; or, Nature’s System of Constructing a
Stratified Physical World, by William Andrews (T. C. C.), 76; Memoirs of the
Geological Survey of the United Kingdom ; The Silurian Rocks of Britain, by
B. N. Peach, John Horne, and J. J. H. Teall (W. N. Logan), 77; Genesis of
Worlds, by J. H. Hobart Bennett (G@isGnC). 70; lext-Book: of Paleontology,
by Karl A. von Zittel (Charles R. Keyes), 81; The Gold Measures of Nova
Scotia and Deep Mining, by E. R. Faribault (C. K. L.), 84; Maryland Geo-
logical Survey (James H. Smith), 86; Maryland Weather Service (James Tal.
Smith), 87; Principles and Conditions of the Movement of Ground Water, by
Franklin Hiram King, with a Theoretical Investigation of the Motion of
Ground Waters, by Charles Sumner Slichter (T. C. C.), 89 ; Les Lacs Frangais,
by André Delebecque (R. D. S.), 91; On the Building and Ornamental Stones
of Wisconsin, by E. R. Buckley (T. C. H.) 97; Irrigation and Drainage : Prin-
ciples and Practice of their Cultural Phases, by F. H. King (T. C. C.), 100;
The Coos Bay Coal Field, Oregon, by Joseph Silas Diller (W. T. Lee), 100.

RECENT PUBLICATIONS - = E - 2 - - - - = = TOD
NUMBER II.

THE NOMENCLATURE OF FELDSPATHIC GRANOLITES. H. W. Turner - - 105

THE GEOLOGY OF THE WHITE SANDS OF NEW MEXICO. ©, li, lsigan@k = WZ

THE ORIGIN OF NITRATES IN CAVERN EARTHS. William H. Hess - = 129

THE CALCAREOUS CONCRETIONS OF KETTLE POINT, LAMBTON COUNTY,
OnTARIO. Reginald A. Daly” - = = - - - - - 135

Ants as GEOLOGIC AGENTS IN THE TROPICS. John C. Branner - - I51

VARIATIONS OF GLaAziIERS. V. H. F. Reid = - - - 2 = Ubyil

iii

iv CONTENTS OF VOLUME VIII

STUDIES FOR STUDENTS: The Properties of Building Stones and Methods of
Determining their Value. E.R. Buckley - = ; - = = Ge

EDITORIAL - - - - - - : : : J 3 a a) rs

REVIEWS: Om klimatets andringari geologisk och historisk tid sampt deras
orsaker, by Nils Ekholm (J. A. Udden), 188; Sveriges temperaturforhallenden
jamforda med det ofriga Europas, by Nils Ekholm (J. A. Udden), 193; Physi-
ography of the Chattanooga District in Tennessee, Georgia, and Alabama, by
C. Willard Hayes (F. H. H. C.), 193; Geology of Minnesota, by N. H. Win-
chell, U. S. Grant, Warren Upham, and H. V. Winchell (L. M. Fuller), 197;
The Ore Deposits of the United States and Canada, by James F. Kemp (T. C:
H.), 201; The Fauna of the Chonopectus Sandstone at Burlington, lowa, by
Stuart Weller (H. F. B.) 202.

RECENT PUBLICATIONS - - - - = - . - - eZOd
NUMBER TT:
-EDWARD ORTON. John J. Stevenson - : - - = = = = 205
GRANITIC ROCKS OF THE PIKES PEAK QUADRANGLE. Edward B. Mathews - 214
A NorTH AMERICAN EPICONTINENTAL SEA OF JURASSIC AGE. W. N.
Logan - - . Sty = : = - - - - 2a
EDITORIAL - - - - = - = : = : = - Se AG Al

Reviews: A Preliminary Report on the Geology of Louisiana, by G. D. Harris
and A. C. Veatch [John C. Branner),277; On the Lower Silurian
(Trenton) Fauna of Baffin Land, Charles Schuchert (Stuart Weller), 279;
The glacial Palagonite-Formation of Iceland, Helgi Pjetursson (T. C.
C.), 280; Fossil Flora of the Lower Coal Measures of Missouri, by David
White (C. R. Keyes), 284; The Devonian ‘‘ Lampry” Palaeospondylus
Gunni, Traquair, Bashford Dean (C. R. Eastman), 286; Some High
Levels in the Postglacial Development of the Finger Lakes of New.
York, by Thomas L. Watson (W.G. T.), 289; Twentieth Annual Report
of the U. S. Geological Survey, Mineral Resources of the United States,
1898 (T. C. H.), 290; Les Charbons, Brittanniques et Leur Epuisement,
Ed. Loze (W. N. Logan), 291; Cape Nome Gold Region), F. C. Schra-
der and A. H. Brooks (C. R. Keyes), 293; Syllabus of Economic
Geology, John C. Branner and John F. Newsom (R. A. F. P. Jr.), 294.

RECENT PUBLICATIONS - 2 = ra : = - - - - - 296

NUMBER IV.

METHODS OF STUDYING EARTHQUAKES. Charles Davison - - - = BO

GLACIAL GROOVES AND STRIAE IN SOUTHEASTERN NEBRASKA. Erwin
Hinckley Barbour - - = : - = = = - =, 3X08)

CONTENTS OF VOLUME VIII

A Novice oF A NEW AREA OF DEVONIAN ROCKS IN WISCONSIN. Charles E.
Monroe - - - - - =

KINDERHOOK STRATIGRAPHY. Charles R. Keyes -

ON THE PROBABLE OCCURRENCE OF A LARGE AREA OF NEPHELINE-BEARING
RocKS ON THE NORTHEAST COAST OF LAKE SUPERIOR. Frank D.
Adams . - - - - - . - - - - =

A NOTE ON THE LAST STAGE OF THE ICE AGE IN CENTRAL SCANDINAVIA.
Hans Reusch 7 = = - = : : 2 2 : z

STUDIES FOR STUDENTS: The Properties of Building Stones and Methods of
Determining their Value. Part II. E.R. Buckley — - - - -

‘EDITORIAL - - E = : 2 E Ee : : i

REVIEW: The Illinois Glacial Lobe, by Frank Leverett (T. C. C.), 362; Pre-
liminary Report on the Copper-bearing Rocks of Douglas County, Wis-
consin, by Ulysses Sherman Grant (R. D. George), 370; Upper and
Lower Huronian in Ontario, by Arthur P. Coleman (R. D. George),
370; Mesozoic Fossils of the Yellowstone National Park, by T. W. Stan-
ton (W. N. Logan), 371; The Glacial Gravels of Maine and their Asso-
ciated Deposits, by George H. Stone (T.C.C.), 373; Lower Cam-
brian Terrane in the Atlantic Province, by C. D. Walcott (R. D.
George), 375; Forest Reserves (W. N. Logan), 376; Geology of Narra-
gansett Basin, by N. S. Shaler (R. D. George), 377; On the Lower
Silurian (Trenton) Fauna of Baffin Land, by Charles Schuchert (R. D.
George), 378; The Freshwater Tertiary Formations of the Rocky
Mountain Region, by W. M. Davis (T. C. C.), 379; The Crystal Falls
Iron-bearing District of Michigan, by J. Morgan Clements and Heary
Lloyd Smith (J. P. I.), 382; The Geography of Chicago and its
Environs, by Rollin D. Salisbury and William C. Alden (Charles Emer-
son Peet), 384.

RECENT PUBLICATIONS -

NUMBER V.

IGNEOUS: ROCK SERIES AND MIXED IGNEOUS Rocks. Alfred Harker -
ON THE HABITAT OF THE EARLY VERTEBRATES. T.C. Chamberlin - -

THE BIOGENETIC LAW FROM THE STANDPOINT OF PALEONTOLOGY. James
Perrin Smith = - - £ f é 4 x 2 p

THE LOCAL ORIGIN OF GLACIAL DRIFT. R.D. Salisbury - : = -

SUMMARIES OF CURRENT NoRTH AMERICAN PRE-CAMBRIAN LITERATURE.
C. K. Leith = : = 2 2 : E Z 2 a

STUDIES FOR STUDENTS: The Eocene of North America West of the tooth
Meridian (Greenwich). James H. Smith - < 2 : :

EDITORIAL - = = 3 4 E s E E 2 “ Z i

387

389
400

413
426

433

444
472

vi CONTENTS OF VOLUME VIII

REVIEWS: Department of Geology and Natural Resources of Indiana, Twenty-
fourth Annual Report, by W. S. Blatchley (C. E. S.), 475; The Geogra-
phy of the Region About Devil’s Lake and the Dalles of the Wisconsin,
with Some Notes on its Surface Geology, by Rollin D. Salisbury and
Wallace A. Atwood (KF. H. H.C.), 477; A Preliminary Report on a
Part of the Clays of Georgia, by George E. Ladd (R. D.S.), 479; Pre-
liminary Report on the Clays of Alabama, by Heinrich Ries (R. D. S.),

479.

NUMBER VI.

THE ORIGIN OF BEACH Cusps. J.C. Branner - - = = - -
A CONTRIBUTION TO THE NATURAL HisToRY OF Maru. Charles A. Davis
A REMARKABLE MARL LAKE. Charles A. Davis - - - - = =

THE ORIGIN OF THE DEBRIS COVERED MESAS OF BOULDER, COLORADO.
Willis T. Lee = : eu 2 2 : e = Z é 3

SUMMARIES OF CURRENT NORTH AMERICAN PRE-CAMBRIAN LITERATURE.
CK Veith - - - - - - - - - - -

Stupigs For STUDENTS. Results of Tests of Wisconsin Building Stone, Part
Ill. E.R. Buckley . - - - - - - - - - -

Reviews: Glacial Erosion in France, Switzerland, and Norway, by William
Morris Davis (T. C. C.), 568; Bartholomew’s Physical Atlas: An Atlas
of Meteorology, by J. G. Bartholomew, and A. G. Herbertson, edited by
Alexander Buchan (J. Paul G.), 573; Mineral Resources of Kansas,
1899, Erasmuth Haworth (T. C. C.), 577; Results of the Branner-
Agassiz Exposition, 578; I. The Decapod and Stomatopod Crustacea,
by Mary J. Rathbur; II. The Isopod Crustacea, by Harriet Richardson ;
III. The Fishes, by Charles H. Gilbert; IV. Two Characteristic Geo-
logic Sections on the Northeast Coast of Brazil, by J. C. Branner (T. C.
C.), 579; Progress of Geologic Work in Canada During 1899, by Henry
M. Ami (C.), 579; Descriptive Catalogue of a Collection of the Econo-
mic Minerals of Canada, Paris Exposition, 1900, 579.

RECENT PUBLICATIONS - = : : Z p 2 = oe eee z

NUMBER VII.

DE LA COOPERATION INTERNATIONALE DANS LES INVESTIGATIONS GEOLO-
GIQUES. Archibald Geikie = 2 2 = 2 Z R 5

PROPOSED INTERNATIONAL GEOLOGIC INSTITUTE. T. C. Chamberlin -
THE COMPOSITION OF KULAITE. Henry S. Washington - > = =

SUCCESSION AND RELATION OF LAVAS IN THE GREAT BASIN REGION. J. E.
Spurr. - 5 = 5 = ‘ B és g , :

THE GLACIER OF MT. ARAPAHOE, COLORADO. Willis T. Lee - -

481
485
498

504

512

526

580

585

596

610

621
647

CONTENTS OF VOLUME VIII

THE SHENANDOAH LIMESTONE AND MARTINSBURG SHALE. Charles S.
Prosser - - - - - - - - - - - 2

Reviews: Geology of the Little Belt Mountains, Montana, with Notes on the
Mineral Deposits of the Neihart, Barker, Yogo, and other Districts,
Walter Harvey Weed, accompanied by a report on The Petrography of the
Igneous Rocks of the District, by L. V. Pirsson (J. P. I.), 664. Geolog-
ical Survey of Canada— Annual Report of Mineral Statistics for 1898,
by E. D. Ingall (C.), 667. On the subdivisions of the Carboniferous
System in Eastern Canada, with Special Reference to the Union and
Riversdale Formations of Nova Scotia, Referred to the Devonian System
by some Canadian Geologists, by H. M. Ami (T.C. C.), 667. Trans-
actions of the Australasian Institute of Mining Engineers, Vol. VI,
edited by A. S. Kenyon, 668.

RECENT PUBLICATIONS - 5 = = - = = = - -

NUMBER VIII.

PRINCIPLES OF PALEONTOLOGIC CORRELATION. James Perrin Smith =

CONTRIBUTIONS FROM WALKER MusEuM. I. THE VERTEBRATES FROM
THE PERMIAN BONE BED OF VERMILION CouNTyY, ILLINOIS.
E. C. Case - - - - - Ste a= - - - -

SOME PRINCIPLES CONTROLLING THE DEPOSITION OF ORES. C. R. Van Hise

REVIEWS: Secondary Enrichment of Ore Deposits, S. F. Emmons; Enrich-
ment of Gold and Silver Veins, by Walter Harvey Weed (Charles R.
Keyes), 771. Enrichment of Mineral Veins by Later Metallic Sulphides,
by Walter Harvey Weed (J. P.I.), 775. Origin and Classification of
Ore Deposits, by Charles R. Keyes (C. F. M.), 776. Eléments de
Paléobotanique, by R. Zeiller (H. C. Cowles), 779. A Topographic
Study of the Islands of California, by W.S. Tangier Smith (R. D. S.),
780. ;

RECENT PUBLICATIONS - - - - ~ : - - - -

Vil

669

673

608
730

783

one Nirah

Lou NAO GEOLOGY

FANUARY—FEBRUARY 1900

SUGGESTIONS REGARDING THE CLASSIFICATION
OF THE IGNEOUS ROCKS

IT may well be doubted if there is any science which presents
greater difficulties to the teacher than that of systematic petrol-
o; y—the classification of rocks. Even the name itself is seldom
us ,and appeals to the petrologist as almost a misnomer, because
th science is so lacking in system, or, shall we say, over-
burdened by ‘“‘systems.”” The German petrologists, under the
leadership of Rosenbusch and Zirkel, and the French with
Michel-Lévy at their head, are committed to the partial use of

)

‘“‘systems’’ which are regarded as obsolete by their colleagues
in other lands. The English and American schools of petrology
have each their ‘‘systems” which differ from the German
‘“systems’’ and more or less from each other. Yet as all are
using essentially the same language of terms, the confusion which
has arisen is so great that it is now necessary in employing a
rock aame to state at length what meaning the word is intended
to convey.

Such a state of affairs is explainable on two grounds: first,
the hesitancy felt in departing from the views held by the
fathers of the science, and, second, the inherent difficulties
which lie in the science itself, due to the complex nature of
rocks.

Vol. VIII, No. 1. I

WM. H. HOBBS

N

The modern petrographical microscope, with its accessories,
has introduced great refinement into the methods of study, so
that descriptive petrology, or petrography, has become a very
exact science. It is now possible to describe a rock in so many
ways (in respect to so many of its attributes, such as mode of
occurrence, texture, mineral composition, chemical composition,
alterations, genesis, etc.,) that the difficulties in the way of bring-
ing the results of the study into an orderly classification have
been greatly increased. Nor is there reason to hope for any
immediate remedy for this condition, since the largest and most
representative body of petrologists ever assembled —the Seventh
International Congress of Geologists, at St. Petersburg — was
almost unanimous in the conviction that it would be useless to
attempt to harmonize the nomenclature of the science by any
‘early action of that body. The view was, however, expressed
that something might be accomplished through the labors of a
representative committee, which should, by frequent and careful
deliberations, arrive at a tentative scheme for presentation to a
future congress.

Undoubtedly the greatest obstacle in the way of reaching an
understanding in the matter is that different values are assigned
by different petrologists to the same attribute in rock classifica-
tion. Some would lay greatest stress upon the mode of occurrence
in the field ; others would give the first place to mineral constitu-
tion, still others to texture, chemical composition, etc.

LAE FIELD) GEOLOGIST Vs> Li PEDROLOGISE

In deciding what shall be given first place as a basis in any
system of rock classification, it should be realized, it seems to
me, that the igneous rocks are not the sole property of the
petrographer. The field geologist or the ‘‘naturalist,’’ whatever
be his special line of work, has need to make determination of
igneous rocks, and he has a right to ask of the petrographer,
who from his greater familiarity with rocks is charged with
arranging them in an orderly system, such a classification that
the geologist’s determination in the field shall be zxcomplete rather

THE CLASSIFICATION OF THE IGNEOUS ROCKS 3

than zncorrect. It should be made possible for the geologist
to determine correctly at least the family to which a rock
belongs, leaving to the petrographer the determination of
rock species as well as the solution of the purely petrological
problems.

To aid his eye the field geologist has only his pocket lens,
and whatever rock species are fixed upon by petrologists they
should be grouped into a comparatively small number of families,
limited by simple and easily tested characteristics. In the case
of the volcanic rocks it would be necessary to adopt terms broad
enough to cover all rock types which it is found impossible to
easily distinguish in the field. This reform would be made in
the interest of the petrographer quite as much as of the geologist.
If this be done the petrologist may multiply terms as he will to
express any extension of his refined methods of study without
in any way disturbing the composure or the effective work of the
great body of field geologists.

BEARING OF RECENT PETROGRAPHICAL STUDIES ON ROCK
CLASSIFICATION

From the point of view of the systematic petrologist the two
most significant developments of petrology during the closing
years of the nineteenth century have been, first, the numerous
observations showing that the time honored families of igneous
rocks, once supposed to be more or less sharply delimited, pass
by insensible gradations into one another; and second, the return
of chemical composition as a basis of rock classification to a
position of prominence nearer to that which it formerly occupied.

The attention of petrologists was first drawn to the marked
facial differentiation of a rock magma when the late Professor
George H. Williams showed that rocks as diverse as quartz-mica-
diorite and peridotite occur in the same stock near Peekskill,
N.Y... Since that time other investigators, but notably Iddings,
Brégger, Ramsay, and Weed and Pirsson, have multiplied the

1G, H. WitLiaMs, The Gabbros and Diorites of the “Cortlandt Series,” on
the Hudson River near Peekskill, N. Y. Am. Jour. Sci. (3) XXXV, pp. 438-448,
1888.

4 WM. H. HOBBS

observations of other but similar cases of magmatic differentiation.
It is now the exception rather than the rule to discover an
igneous rock mass of considerable dimensions in which some
evidence of such gradations may not be observed.

The introduction of the petrographical microscope and its
accessories, bringing as it did quick and delicate methods for
determining the mineral constitution of a rock, naturally enough
drew away the attention of petrographers from the slower and
less brilliant methods of chemical analysis, which up to that
time had been almost the only ones in use. Moreover most of
the analyses of the period were, as we now know, inaccurate and
failed to show the real chemical differences between individual
rocks. The multiplication of the number of analyses and the
improvements in the methods of rock analysis which have been
made during the last decade, particularly by Hillebrand, have
disclosed important differences among rocks formerly classed
together, and thus necessitated a considerable elaboration of the
systems of classification.

With this elaboration rock names have been introduced into
the science with a rapidity which is little short of bewildering.
The older petrological nomenclature was largely binomial or
polynomial (2. e., mica-syenite, quartz-mica-diorite) though the
recent names seem planned for a monomial nomenclature (7Z. @., |
ciminite). It is therefore not strange that misunderstanding has
arisen in some quarters, where it is not realized that the new
names proposed are for the most part specific and varietal in
their nature and in no way to be correlated with the great family
names such as granite or gabbro, and hence a protest has been
made against what seems a needless overburdening of the science
with names. Without entering upon this question here it may,
I think, be stated with all assurance that some reforms are
imperatively demanded before the worker will be fully equipped
to discover the relationships among rocks because of the incubus
of unclassified facts by which the science is now encumbered.
Some of the particular reforms which to me seem desirable and
practicable will be briefly described.

THE CLASSIFICATION OF THE IGNEOUS ROCKS 5

The definition of a rock as an object rather than as an integral
part of the earth’s crust—The Wernerian conception of a rock asa
geologica] unit or integral part of the earth’s crust, still held by
German petrologists, was adequate enough so long as rock
masses were regarded as essentially homogeneous. With the
discovery that such masses are usually quite heterogeneous and
frequently represent not only several rock species but sometimes
include almost the whole gamut of rock families, it became
necessary to adopt some other definition. No other course
seems open under these circumstances than to consider the indi-
vidual rock specimen as the unit of classification and describe it
primarily as an object, as is done with the units in the systems
of other sciences.* If this is done it should be possible to name
a rock from study of the specimen only though the full descrip-
tion would involve no less of field study than is undertaken
when rocks are classified on the basis of their geological occur-
rence.

The importance of texture as a basis of classification.— All sys-
tems of classification of the igneous rocks emphasize more or
less strongly rock texture as a basis of classification, for the
reason that the texture is one of the’properties of a rock most
easily examined; and, further, because it is dependent so largely
upon the peculiar conditions of rock consolidation or subsequent
metamorphism. If rocks are described as objects this property
of texture becomes inevitably of the very first importance.

The two main groups of the igneous rocks which are now
generally recognized as distinguishable on the basis of texture
are: first, those having a texture designated by Rosenbusch as
hypidiomorphic granular, but which may in simpler language be
referred to as granitic, the essential characteristic of which is
that the mineral constituents by their manner of interlocking
indicate for the rock in which they occur practically an uninter-
rupted period of crystallization; and, second, the porphyritic

™Cf. WHITMAN Cross, The Geological vs. the Petrological Classification of
Igneous Rocks. JourN. GEOL. VI, p. 79, 1898. See also TEALL, British Petrography,
p. 65.

6 WM. H. HOBBS

texture in which the occurrence of two or more generations of
the same constituent mineral indicates that the process of con-
solidation was not a continuous one but consisted of two or more
stages.

The time honored but now obsolescent classification of igne-
ous rocks on the basis of geological age has left us as alegacy a
double nomenclature for the rocks of porphyritic texture, and
this may be well illustrated by the terms “quartz porphyry” and
‘rhyolite’? applied to rocks of porphyritic texture having a
chemical composition similar to the granites. The former in its
traditional, and also in its present German signification, refers to
rocks of pre-Tertiary age, the latter to Tertiary or later rocks.
The tendency of American petrographers seems to be to aban-
don entirely terms of the class of ‘‘quartz porphyry’’ and to
extend the terms correlated with ‘‘rhyolite”’ to cover the rocks
which were previously included in both groups. This tendency.
seems to me to be an unfortunate one since it results in classing
together rocks which are essentially unlike. There may be no
important difference between a particular ‘‘quartz porphyry ’”’ and
a particular ‘“‘rhyolite,”’ but compare a drawer of hand specimens
of the former with one of the latter and argument is unnecessary
to show that as classes they are essentially different. The
‘‘quartz porphyries”’ are, as a class, devoid of -vesicular and
fluxion structures—they are in their mode of occurrence hypa-
byssal—and they more generally show the effects of devitrifica-
tion, weathering, etc.

The ‘‘rhyolite” class of rocks may be conveniently distin-
guished from the ‘“‘quartz porphyry” class by the possession
of either vesicular or rhyolitic (fluxion) textures. Correspond-
ence with some representative American petrographers has indi-
cated to me that a restriction of the terms, rhyolite, trachyte,
andesite, basalt, etc., to describe porphyritic types possessed
of rhyolite or vesicular textures, would meet with considerable
favor. Though of these terms rhyolite alone in its derivation
calls attention to a fluxion texture, the others by their usage
(trachytic structure, andesitic structure, etc.) have been given

THE CLASSIFICATION OF THE IGNEOUS ROCKS 7

the same significance. . The terms, rhyolite-porphyry, trachyte-
porphyry, andesite-porphyry, etc., by their substitution for the
objectionable names, quartz-porphyry, quartzless porphyry, etc.,
would carry with them the idea of varietal rather than specific
variation from the family type, and would, moreover, obviate
the danger of their being interpreted in terms of the age classi-
fication.

Combination of chemical and mineralogical composition as a basis
for rock classification Probably the majority of those petrolo-
gists who define rocks as objects would agree that chemical and
mineralogical composition with texture should occupy the fore-
most places in rock classification.’ It would probably be more
satisfactory, were it practicable, to adopt chemical composition
divorced from mineral composition as the primary basis in
classification, but we are, per force, compelled to look first to
the mineral composition, and work backward from this to the
chemical composition —the chief factor in determining mineral
composition. In the past the mineralogical examination of
rocks has been largely qualitative, resulting, in some cases, in
the classing together of rocks strikingly different as regards
their ultimate chemical composition, but a stage has now been
reached where such a method is no longer adequate. Pirsson
has called attention to the necessity of paying greater regard to
the relative quantities of the several essential constituents of a
rock, thus making a rough estimation of its ultimate chemical
composition.”

Specific, generic, and family rock names are applied to arbitrary rock
types separated from one another by no sharp lines.— It follows, from
the gradations generally observed to connect the families of the
igneous rocks, that the names which we adopt to designate any
individual rock, or class of rocks, is applied as aZype name in the
sense that it applies to a particular rock or collection of related

1Cf. TEALL: British Petrography, p. 69; WHITMAN Cross: loc. Gilig, DotKOS Io 1ee
Ipprincs: On Rock Classification, JouR. GEOL., 1898, VI, p.93; F. ZIRKEL: Lehrbuch
der Petrographie, I, p. 829, 1893; W. C. BrOGGER: Die Gesteine der Grorudit-
Tinguait Serie, Christiania, 1894, p. 92.

2Tgneous Rocks of Yogo Peak, Montana, Am. Jour Sci. (3) L, p. 478.

(oe)

WM. H. HOBBS

rocks, descriptions of which have been placed onrecord. The lines
separating the several types are fixed arbitrarily, and would, in
general, be located somewhat differently if undertaken at the
outset by different individuals. For the types of larger order,
these lines have been fixed by the traditional rock groups, and
they are not likely to be much changed, but for the new and
specific types they will be largely determined by the particular
rock areas which are first examined.

A much more general use of intermediate family type names
is inevitable, and terms like grano-diorite (or better, granito-
diorite), trachy-andesite, etc., should be utilized."

Rock relationships should be indicated by the combination of names
into a binominal, or, if necessary, polynominal nomenclature.—The
multiplication of specific terms, whose derivation has only a
geographical signification (¢. g., Toscanite, Absarokite, Litch-
fieldite), furnishing not the slightest indication of the rock’s
relationships, is fast bringing petrologists to the condition of
the Chinaman who is required to learn a unique syllable for
every word in his language. Not possessing the admirable
memory training of the Chinaman, the petrographer finds him-
self somewhat bewildered under the rain of new petrographical
names which has characterized the closing years of the century.
Many of these terms have been rendered necessary by the elabo-
ration of the system of classification, due to the improved
methods of chemical examination, and to the discovery of new
petrographical provinces, and others are sure to be needed, but
the enterprise in this branch of the science manifested in some
quarters has sometimes provided us with two, or even three,
names for the same specific rock type.

There can be no question that the nomenclature of petrog-
raphy can be greatly simplified by a return to a binomial or
polynomial nomenclature, which, fortunately, can be accom-
plished without much confusion, provided the old names of rock
families be retained, together with compound names for the
gradational types connecting them. An illustration may be

Cf. BROGGER: op. cit., p. 93.

TAENCLASSIFICATION OF THE [IGNEOUS ROCKS 9

furnished by the interesting types, Toscanite, Vulsinite, and Cim-
inite, recently described by Washington.t They form together
an intermediate family connecting the trachytes with the andes-
ites, and called by Washington, trachy-dolerite, though it seems
to me trachy-andesite is to be preferred. Trachy-dolerite-
ciminite, or trachy-andesite-ciminite, is a term which tells at
once that the rock to which it applies is a species of trachy-
andesite which has been described from Monte Cimino. The
term latite proposed by Ransome? for this group, while other-
wise appropriate, fails to show the family relationships. Van
Hise? has already suggested such a compounding of terms to
express relationships. Certainly if the nomenclature of the
science is to aid rather than to distract the worker some such
reform from present conditions is demanded.

Graphical methods essential to a comprehensive study of rock
analyses—TVhe necessity for studying the chemical composition
in connection with the mineral composition of a rock requires
that we examine in connection with one another the chemical
analyses of all rocks having the same mineral constituents; or,
better, those having the same constituents in the same relative
quantities to a rough approximation. Such analyses show varia-
tions of one, two, or more per cent. in the quantities of some of
the constituents for a single species or variety. But, on the
other hand, differences of one or two per cent. in the amount of
a constituent may be the cause of important differences in
mineral composition or in other characteristics of the rock; hence
it is important to know to that degree of precision the amount
of each constituent which is present. For each analysis that
would be remembered, it is necessary, then, to keep in the mind
eight numbers of one or two figures each; and the student of
petrology who would be familiar with the chemical nature of any

tH. S. WASHINGTON: Italian Petrological Sketches, No. 5, JouR. GEOL., V,
PP- 349-377; 1897.

?F, LESLIE RANSOME: Some Lava Flows of the Western Slope of the Sierra
Nevada, Cal., Am. Jour. Sci. (4), V, p. 373, 1898.

3C. R. VAN HisE: The Naming of Rocks, Jour. GEOL., VII, pp, 691-693, 1899.

IO WM. H. HOBBS

given rock type must know the range in the percentages of the
eight principal constituents. Moreover, he is not assisted in this
by the knowledge that the upper and lower limits which he learns
for a constituent of one species are at the same time, respect-
ively, the lower and the upper limits for the same constituent in
other allied species. A tax is thus imposed upon the memory far
beyond what it may be reasonably expected to bear, and this tax
is increased with the fixing of each new rock species.

The eye assists the mind not only to discover intricate rela-
tionships, but also to retain them, whenever the facts can be
expressed by a definite form. This has been appreciated espe-
cially by the engineering profession, which has been accustomed,
by the use of diagrams, to set forth in the most lucid manner
facts which only the most laborious methods could otherwise
bring out of the tables on which they are based. A curve con-
tains the essence of pages of figures, and is readily carried in
the mind owing to the large development of that faculty, which
the Germans have so aptly termed Vorschauungsgabe. It is note-
worthy that so little attempt has been made to apply graphic
methods in petrology.

Recently, however, Iddings,* Becke,? Michel-Lévy? and
Brogger+ have each devised diagrams to illustrate rock analyses.

Of these the diagrams of Brégger seem to me the ones best
adapted for general use because the simplest and the most char-
acteristic. In the Bréggers diagram are set off on radius vectors
the amounts of the eight principal chemical constituents reckoned

tJ. P. Ippines: The Origin of the Igneous Rocks, Phil. Soc. of Washington.
XII, pp. 89-214. Pl. II, 1892; Absarokite-shoshonite-banakite series. JOUR. GEOL.,
III, pp. 90-97, 1895; On Rock Classification, zézd., VI, p. 92, 1898; Chemical and
Mineralogical Relationships in Igneous Rocks, 2d2d., p. 219.

2F. BECKE: Die Gesteine der Columbretes. TSCHERMAK’S min. u. petrog.
Mittheil., VI, p. 315. 1897.

3M. MicHEeL-LEvy: Porphyr bleu de l’esterel, Bull. de la service de la carte géol.
de la France. TomeIX, No. 57, 1897; Sur une nouveau mode de co-ordination des
diagrammes representant les magmas des roches éruptifes. Bull. de la soc. géol. de la
France. (3) XXVI, p. 311.

4W.C.BrOcGER: Die Eruptivgesteine des Kristianiagebietes; Das Ganggefolge
des Laurdalits. Kristiania, 1898, p. 255. Pl. I.

5Or LEVY-BROGGER diagram.

TIE CLASSIFICATION (OF THE IGNEOUS ROCKS Tel

in molecular ratios, ferrous and ferric iron being entered upon the
same radius vector, and silica, because so much in excess of
the others, being evenly divided between the two horizontal
radius vectors. A broken line joining the intercepts on the
eight radius vectors forms a polygon, which may be long and
narrow, or short and thick, convex above or below, or reéntrant
in any portion, left or right handed, etc., according to the chem-
ical constitution of the rock.

2)

%
g

SiQ

Wie, ip

When viewed in this diagram, the rock comes to have a
handwriting by which it may be instantly recognized. When
drawn to scale, this diagram not only shows the chemical char-
acter of the rock but all the results of analysis. may be quickly
read from it numerically.* In it, as in all other successful
diagrams the molecular ratio is substituted for the percentage of
each constituent. Some authors now publish these ratios with
every rockanalysis. It is to be hoped that this will soon become
a general custom. _

THE COMPOSITE ROCK DIAGRAM

The principal objection to Brégger’s diagram is that it rep-
resents not a rock species or a rock type but only an individual
analysis, the rock type covering a considerable range of differ-
ing analyses. So far as I know, only isolated attempts have
been made to average rock analyses to secure an adequate con-
ception of the chemical constitution of the rock type, although
the method of averaging results is so successfully used in other
fields of science.

*On plates I, IV, V, and VI, .or equals 1™™.

lez WM. H. HOBBS

Jour. GEOL., Vou. VIII, No. 1 Plate I

ISIC GIR AINI TY le

MISS GoW 23st riiis SGSAANITs€

BIOTITE GRANITE

Herineal a iNiG= GitANI T=

AMET GRANT =

GRANITE

BOMIFOSl res

THE CLASSIFICATION OF THE IGNEOUS ROCKS 13

In connection with his class in petrology, the writer has for
some time made use of diagrams which set forth the average
composition of rock types. There are two ways in which such
diagrams may be constructed. On the one hand, the diagram
may be prepared after the same manner as composite photo-
graphs. The Brogger diagrams of a considerable number of
representative rocks faintly outlined are superimposed upon the
same radius vectors, so as to indicate the range in ratios of each
constituent and in the darkest part of the figure the character-
istics of the type. A composite diagram, better adapted for
general use, because so much less intricate and so much easier to
prepare, is obtained by first averaging the molecular ratios of
each constituent for the group of analyses, and using the results
to prepare a single diagram, which then becomes the diagram of
a type instead of that of an individual.

The writer has so far modified the Brégger diagram as to
draw the radius vectors so as to make equal angles with one
another. The closed polygon obtained by connecting the inter-
cepts on the different radius vectors has a form which changes
in a marked degree to correspond with the changes in the length
of any radius vector. Since the soda, potash, and alumina are
all measured below the horizontal, acid rocks show diagrams
stretched out along the horizontal and developed also below the
horizontal; while the protoxide bases being all entered above
the horizontal basic rocks are short and ‘‘fat above.” Soda-
rich or potash-rich rocks give respectively left-handed and right-
handed diagrams, etc. All these facts the eye soon accustoms
itself to take in at a glance and subconsciously, as it does
in the case of handwriting. It is hardly necessary for the eye to
estimate the lengths of the intercepts (a feat it is but poorly
qualified to accomplish) for the ratios of the quantities of the
constituents to one another is shown by the angles of slope of the
polygonal sides —something which the eyes easily measures.
The larger the number of correct and properly selected analyses
which are utilized in obtaining the ‘‘ composite”
the greater is its value.

of any type,

WM. H. HOBBS

14

SHYNLX4L JILINVYES

SNIAWH

(SSNINYV 4) SSdGAL MO0H WdIONIdd

leletie. JUL

FLiodisd Lage
Ss LiISQaneo
SaLivaseea SLINSAS 4N43 1SHd4aN
SLINSXOvAd
SLINSAS FIV IV
SU Wiel srl
OvyseaVva
SLINSAS
SLINIXNOHS

Jour. GEOL., Vou. VIII, No. 1

4 LINVHS

THE CLASSIFICATION OF THE IGNEOUS ROCKS Is

STUDY OF THE COMPOSITES OF THE PRINCIPAL FAMILY TYPES OF
THE IGNEOUS ROCKS HAVING GRANITIC TEXTURE

The composite diagram may be made to represent either
specific or family types according to the analyses which are
combined to produce it. By combining separately analyses of
the principal species of granite, viz., alkali-granite, muscovite-
biotite-granite, biotite-granite, hornblende-granite, and augite-
granite, we are prepared to draw the composite diagram of each
and can then compare them with one another ; or, if we choose,
we may compose all to form a single composite, which then rep-
resents not a specific but a family type—granite. These granite
composites may be studied in Plate I. The alkali-granite com-
posite is composed from six analyses, the muscovite-biotite-
granite from two, the biotite, hornblende, and augite-granites
each from four, so that the family composite is made from the
average of twenty analyses.

The composites of each of the families of the igneous rocks
having granitic textures may be similarly prepared and studied
in connection with one another. (See Plate II). The family
types Selected, viz., granite, syenite, alkali-syenite, nephelene-
syenite, shonkinite, theralite, essexite, diorite, gabbro (including
hypersthene-gabbro and norite), pyroxenite, and peridotite,
when seen in their composites allow their peculiar characteris-
tics to be read at a glance.

The granites are distinguished from all the other families by
their excess of silica and, moreover, by the small quantities of the
protoxide bases and moderate amounts of alumina and the alka-
lies. The grantes, alkali-syenites, and nephelene-syenites form a
progressive series which ts characterized by decreasing silica and
rapidly increasing soda and alumina, and to a less degree by wcreas-
ing potash and lime, so that the alkali and nephelene-syenite rocks
become preéminently the alkalt-alumina rocks.

The shonkonites, theralites, and essexites form a second progressive
series in which the silica and tron remain nearly constant but in which
the potash, magnesia, and lime steadily decrease as the soda and
alumina increase. The essexites are essentially alkali-diorites

16 WM. H. HOBBS

Jour. GEOL., VoL. VIII, No. 1 Plate III

BOC WA 2 y=
Rockall Bank

=, a

VYeaeGolreEe
Beaver Crk., Mont
WA dale

Lujaur-Urt,Kola.

SASIO NEP. SyYeNit=

Beemerville,N.Jd.

OWN ThE
Elliott Co.,Ky.

lL) T=
Wola.
Tiwaara,Finland.

MISiSi@l el Rilisi=s
itighwood Mets.,Monb.

SOME RNA Frock Tres

(GRANITIGC TEXTURE)

THE CLASSIFICATION OF THE IGNEOUS ROCKS 7,

distinguished from the diorites by a gain of alkalis, lime and
iron, and a loss of silica.

The affimties of the syenites are seen to be entirely with the diorites
and gabbros, with which they form a third progressive series which is
continued imperfectly in the pyroxenites. In this series, characterized
by generally decreasing silica and potash, the magnesia, lime, iron,
and alumina increase, soda remaining practically constant throughout.
The pyroxenites and peridotites, so poor in alkalis and alumina,
show close affinity with each other and with the gabbros.

A few petrographical curiosities are represented in Plate III
— rocks so exceptional in their occurrence as to be almost or
quite unique. The first of these is Rockallite from Rockall
Bank in the northeastern Atlantic,* a rock of granitic tex-
ture chemically closely related to the pantellerites of Firstner
(see Plate VII); Urtite is a nearly pure nephelene rock from the
Kola peninsula? in arctic Russia which forms the limiting mem-
ber of the nephelene-syenite family. Yogoite from Montana;
iseay asic wsyemite., Nhe “basic miephelene-syenite . from
Beemerville, N. J.,* furnishes the most symmetrical of all the
diagrams and gives indication of no near relationship to any
other specific rock type though it is classed with the nephelene-
syenites. The dunite from Elliott county, Kentucky 5 is so low
in silica and so high in magnesia as to be very exceptional,
though its diagram conforms to the general shape of the peri-
dotite composite. Ijolite® and Missourite’, the two recently

tJoHN W. JuDD: Notes on Rockall Island and Bank (Notice of Memoir) Geol.
Mag., Dec., (4), VI, pp. 163-167, 1899.

2 WILHELM RAmsAy: Urtit, ein basisches Endglied der Augitsyenit-Nephelin-
syenit-Serie. Geol. Foren. Stockh. Foérh., XVIII, pp. 459-468, 1896.

3 WEED and PirssoON : The Bearpaw Mountains of Montana, Am. Jour. Sci., (4),
I, p. 357, 1896.

4J. F. Kemp: A basic Nephelene-syenite from Beemerville, N. J., N. Y. Acad. of
Sci., XI, p. 68, 1892.

SJ. S. DILLER: The Peridotite of Elliott County, Ky. Bull. No. 38, U. S. Geol.
Survey, pp. 1-29, 1887.

6 WILHELM Ramsay : loc. cit.

7 WEED and PIRSSON: Missourite, a New Leucite Rock from the Highwood
Mountains of Montana. Am. Jour. of Sci., (4), Il, pp. 315-325, 1896.

18 WM. H. HOBBS

jouR] Gro, VoL WV TT Nomie Plate IV

GRANITE |

ALKALI! SYENITE

NePrleLieNe s eNiyle

SrAN Pe Neiaines YeNllle Series

S)aliN isk

IONE

GABBRO

SY ENTE CASE R80) Sar is=

THE CLASSIFICATION OF THE IGNEOUS ROCKS iife)

described types for which Rosenbusch has named a new family *
are certainly remarkable types, but except for the quantities of
silica, iron, and lime which they contain, they are as different
from one another as two rock types can be imagined to be.
Ijolite is rich in soda and alumina, Missourite poor ; Ijolite is
poor in potash and magnesia, Missourite rich to excess in both.
Comparison of their diagrams with those represented in Plate IJ
shows that they are the end members of the Shonkinite-Essexite
series, Missourite fitting almost perfectly into the series, being
only a trifle low in lime, and Ijolite failing to do so only being
too high in lime and a bit too low in iron.

The igneous rocks of granitic texture when examined chemically
fall, therefore, quite naturally into three progressive series, which have
distinct and common characteristics. —These series may provisionally
be designated by the limiting families of each, as the granite
nephelene-syenite, missourite-ijolite, and syenite-gabbro series
(Plate IV). The peridotites and pyroxenites do not fall per-
fectly into any of the three, but are yet closely allied to the
syenite-gabbro series.

Granite-nephelene-syenite series Missourite-ijolite series Syenite-gabbro series
Granite family Missourite family Syenite family
Alkali-syenite se Shonkinite Diorite oy
Nephelene-syenite “ Theralite Gabbro s
Essexite of —
Ijolite if Pyroxenite family
Peridotite S

The composite diagrams of the granite-nephelene-syenite
and syenite-gabbro series are shown in Plate IV, those of the
Missourite-ijolite series in Plate V. The common characteristics
of each of the series are well brought out by averaging the com-
posites of the several members in each to form series composites,
as has been done in Plate VI.

Composites of certain igneous rock types having rhyolitic texture.—
No comprehensive attempt has yet been made to determine simi-
lar relationships among the rocks of rhyolitic texture, but com-
posites of a considerable number of the specific rock types of

* ROSENBUSCH : Elemente der Gesteinslehre, p. 179.

20 WM. H. HOBBS

JOUR GEOms, Viola ell INoss Plate V

MSs SS Gi) Se

SlITONi<IINIWsS

i at 2 eA EA i Es

ES SS Earl as =a

[fess Gam) LS aT =

MISSOURITE 2k t= Sea Fias

THE CLASSIFICATION OF THE IGNEOUS ROCKS 21

acid and intermediate composition have been prepared. Plate VII
displays together the composite diagrams of the specific types
belonging to the families which Washington* has designated as
the trachyte, trachy-andesite, trachy-dolerite, and andesite series.

The rhyolite diagram is a composite of nine analyses of
rhyolites from Hungary, Ponza, the Auvergne, Nevada, and
Colorado. The soda-rhyolite composite is compounded from
six analyses, mainly of Wisconsin rocks soon to be described by
C. K. Leith and the writer. The four pantellerites which furnish
the pantellerite diagram are from the island of Pantelleria. The
trachytes, six in number, are those of the Auvergne, Ischia, the
Eifel, the Bohemian Mittelgebirge, and Monte Amiata; and
the two domites were from the Auvergne. The vulcanite dia-
gram is not a composite but an individual rock diagram made
from the type analysis from Vulcano. The six dacite analyses
composed were of rocks from Columbia, Guatemala, Lassen’s
Peak, Cal., and McClellan Peak, Nev., while the seven andesite
analyses used in preparing the andesite composite were of mica-
and hornblende-andesites from the Eureka district, Nev.; Custer
county, Col.; Cartagena, Spain; the Siebengebirge on the Rhine;
Panama; and Columbia. The Toscanite, Vulsinite, and Ciminite
analyses are the Italian ones given by Washington,’ and were
respectively ten, ten, and eleven in number. The Banakites,
Shoshonites, and Absarokites represented in the analyses are
those described by Iddings3 from the Yellowstone National Park
and numbered four, five, and five respectively.

These specific composites are much less interesting as indi-
cating relationships than the composites of a higher order would
be, but they are here introduced to show that the composite
diagram is capable of bringing out the chemical characteristics
of rocks which differ only slightly from one another, as well as
the characteristics of different families.

tH. S. WASHINGTON: Italian Petrological Sketches, V. Jour. GEOL., V, p. 366.
1897.

2H. S. WASHINGTON: loc. cit.

3J. P. Ipp1ines: Absarokite-Shoshonite-Banakite series, Jour. GEOL., III, pp. 935—
959, 1895.

22 WM. H. HOBBS

Jour. GEeou., VoL. VIII, No. 1 Plate VI

ma =

BRAN MesNerresweNile esekiee

MISSOUSPesWOL| = SERIES

Ss (EN TS-EAsiciri) Saslcs

SEES GUE) Gees

23

THE CLASSIFICATION OF THE IGNEOUS ROCKS

Plate VII

Wor Vill Nowe:

98)

Jour. GEOL

SdadAl MOOY DINVOIOA

3 LiMouvseay S41 ISodwo9 3 LIS30NV “=i
aLINOHSOHS | ?
——— 31iova

SLINIWNID

SLIMVNVS
= ae SJLINISTINA
SLINVOSOL ee
3LINOG i

SJLid¥SU1SLNVd
SALINVOTOA v —

SLAHOVYEL :

3 LINTGAHY
ee eS S3LIIOAHY vaoos

24 WM. H. HOBBS

In conclusion, I would suggest to all persons publishing
analyses of rocks the advisability of printing beneath the figures
showing the percentage, composition, the corresponding molec-
ular ratios, and further, that the arrangement of oxides in the
analysis be for the sake of uniformity that which has been con-
sistently followed by Rosenbusch, Washington, and some others,
and which is here used in the composite tables showing the
averaging of analyses for the composite diagrams. The princi-
pal deviation from this order which I have observed is an inver-
sion of the order of magnesia and lime or of soda and potash,
which can hardly be regarded as essential. If these suggestions
be followed, the work of those who examine rock analyses will
be materially lightened and the liability to error in transcribing

will be lessened.
WitiiAM H. Hosss.
UNIVERSITY OF WISCONSIN,
Madison, Wis.

ROCKS WHOSE ANALYSES HAVE BEEN COMBINED TO PRODUCE
THE COMPOSITES OF THE GRANITIC-TEXTURED IGNEOUS
ROCKS

The greater number of the analyses of these rocks are to be found either
in the tables of Rosenbusch’s Elemente der Gesteinslehre, published in 1898
(abbreviation R), or in Clarke and Hillebrand’s Azalyses of Rocks and Ana-
lytical Methods, published in 1897 (abbreviation C and H).

GRANITE ”

. Alkali-granite, Drammen, Norway.

. Alkali-granite, Sandsvar, Gu

Alkali-granite, Pelvoux, Dauphinée, France.

. Alkali-granite, Hardwick quarry, Quincy, Mass., Am. Jour. Sci. (4), 6,
p. 181.

5. Alkali-granite, Montello, Wis., Hobbs and Leith. To be described in a

forthcoming bulletin of the Geol. and Nat. Hist. Survey of Wisconsin.

6. Alkali-granite, Waushara Co., Wis., Bull. No. 3, Wis. Geol. and Nat.
History Survey, 1898, p. 2.

. Muscovite-biotite granite, Hautzenberg, Bayerischer Wald, Germany.

. Muscovite-biotite granite, Katzenfels, Graslitz, Erzgebirge, Bohemia.

FW nN

coomM

t Bull. 148, U. S. Geol. Surv.
2 All the granite analyses with the exception of certain of the alkali granites are
selected from Rosenbusch’s list, on page 78 of the work cited.

me Ww N

N

THE CLASSIFICATION OF THE IGNEOUS ROCKS

. Biotite-granite, Bobritzsch, Freiberg, Saxony,

. Biotite-granite, Barr, Alsace.

. Biotite-granite, Durbach, Black Forest, Baden.

. Biotite-granite, Melibocus, Odenwald, Hesse.

. Hornblende-granite, Mariposa Co., Nevada.

. Hornblende-granite, Pré.de Fauchon, Vosges.

. Hornblende-granite, Syene, Egypt.

. Hornblende-granite, (“‘ Rapakiwi granite”), Finland.
. Augite-granite, Laveline, Vogesen.

. Augite-granite, Oberbruch, Dollerenthal, Alsace.
. Augite-granite, Kekequabic Lake, Minn.

. Augite-granite, Birkrem, Ekersund, Norway.

ALKALI-SYENITE

. Nordmarkite, Tonsenaas, near Christiania, Norway. R. p. 112.
. Pulaskite, Fourche Mt., Arkansas, J/dzd.

. Umptekite, Umpjaur, Kola Peninsula, Russia. /dzd.

. Laurvikite, Laurvik, Norway. Jdzd.

. Sodalite-Syenite, Square Butte, Mont. /dzd.

NEPHELENE-SYENITE

. Nephelene-Syenite, Salem Neck, Mass. Jour. Geol. 8, p. 803.
. Nephelene-Syenite, Great Haste Island, Mass. Jdzd.

Litchfieldite, Litchfield, Maine. C. & H., p. 65.
Nephelene-Syenite, Red Hill, N. H. C. & H., p. 67.

p- 88.

. Lujaurite, Umptek, Kola Peninsula, Russia. R. p. 126.
. Nephelene-Syenite, Beemerville, N. J. C. & H., p. 80.
. Basic Nephelene Syenite, Beemerville, N. J. N. Y. Acad. Sci. 11, p. 68.
. Nephelene-Syenite, Sao Paolo, Brazil. R. 126.

. Laurdalite, Lunde, Norway. Zeitsch. f. Kryst. 16, p. 33.
. Sodalite-Syenite, Kangersluarsuk, Greenland. R. p. 126.
. Urtite, Lujaur Urt, Kola Peninsula, Russia. 02d.

. Leucite-Syenite, Magnet Cove, Ark. Jdzd.

. Borolanite, Lake Borolan, Scotland. J/dzd.

MISSOURITE-IJOLITE SERIES

Missourtte

. Missourite, Shonkin Creek, Highwood Mts., Mont. C. & H. 154.

Shonkinite

. Shonkinite, Beaver Creek, Bearpaw Mts., Mont. C. & H. p. 149.
. Shonkinite, Yogo Peak, Little Belt Mts., Mont. Jdzd.

25

. Nephelene-Syenite, Fourche Mt., Arkansas. Igneous Rocks of Ark.,

26

QO nN =

new N

CON Am FW YN

Nw ew N

WM. H. HOBBS

. Shonkinite, Square Butte, Highwood Mts., Mont. R. p. 176.
. Shonkinite, Monzoni, Tyrol. Zeitsch. d. d. geol. Gesell. 24, p. 201.
. Nephelene-Pyroxene-Malignite, Poobah Lake, Canada. R. p. 176.

Theralite

. Theralite, Gordon's Butte, Crazy Mts., Mont. R. p. 176.
. Theralite, Martinsdale, Crazy Mts., Mont. Jdzd.
. Theralite, Umptek, Kola Peninsula, Russia. Jdzd.

Essextte

. Essexite, Salem Neck, Mass., Jour. Geol., 7, p. 57.

=» JEssexite, salem Necks Massa konp. 172.

. Essexite, Isla de Cabo Fria, Rio de Janeiro, Brazil. J0zd.
. Essexite, Mt. Fairview, Custer Co., Colo. Jbzd.

Essexite, Rongstock, Bohemia. Jdzd.

LTjolite

. Tjolite, liwaara, Finland. R. 180.
. Tjolite, Kaljokthal, Umptek, Kola Peninsula, Russia. zd.

SYENITE-GABBRO SERIES

Syentte

. Mica-Syenite Frohnau, Black Forest, Baden. R. p. 106.

. Mica-Hornblende Syenite, Silver Cliff, Colo. C. & H., p. 169.
. Hornblende-Syenite, Plauenscher Grund, Saxony. R. p. 106.
. Hornblende-Syenite, Biella, Piedmont. zd.

Monzonite, Monzoni, Tyrol. R. p. 109.

. Monzonite, Yogo Peak, Mont. C. & H. p. 147.
. Yogoite, Beaver Creek, Bearpaw Mts., Mont. C. & H. p. 156.
. Akerite, Thingshoug, Norway. R. p. III.

Diorite

. Tonalite, Adamello, Tyrol. R. p. 14o.

. Banatite, Dognacska, Ranat, Austro-Hungary. Jdzd.

. Grano-diorite, near Bangor, Butte Co., Cal. C. & H. p. 204.

ey Dionite el kpVits a Colon Ga Geskl spenlyi7e

. Diorite, Electric Peak, Yellowstone National Park. C. & H. p. 117.
Amphibole-Diorite, Electric Peak, Yellowstone National Park C. & H.

JO We.

. Augite-Diorite, Electric Peak, Yellowstone National Park. C, & H.

ide HEH

. Augite-Diorite, Peach’s Neck, Mass. Jour. Geol. 7, p. 60.
. Diorite, Schwarzenberg, Vogesen. R. p. 140.

Am &W NN -&

THE CLASSIFICATION OF THE IGNEOUS ROCKS Bi,

Gabbro

. Anorthosite, Nain, Labrador. Zeitsch. d. d. geol. Gesell. 1884.

. Orthoclose-Gabbro, Duluth, Minn. Neues Jahrb. f. Min. 1876, p. 117.
. Gabbro, Northwestern Minn. C. & H. p. 112.

. Garnetiferous Gabbro, Granite Falls, Minn. C. & H. p. 113.

. Gabbro, Nahant, Mass. Jour. Geol. 7, p. 63.

. Hypersthene-Gabbro, Baltimore, Md. Bull. U. S. Geol. Survey, No. 28,

P- 39:

. Norite, Montrose Point, Hudson River, N. Y. Am. Jour. Sci. (3) 22,

p- 104.

8. Norite, Ivrea, Piedmont. R. p. 151.

WN 4

. Forellenstein, Neurode, Silesia. /dzd.
. Forellenstein, Coverack, Cornwall. Jézd.

ULTRA-BASIC ROCKS

Pyroxentte

. Websterite, Webster, N.C. C. & H. p. 92.

. Bronzite-Diallage Rock, Hebbville, Md. C. & H. p. 84.

. Hornblende-Hypersthene Rock, Gallatin Co., Mont. C. & H. p. 140.
. Websterite, Johnny Cake Road, Md. R. p. 165.

Peridotite

1. Mica-Peridotite, Crittenden Co., Ky. C. & H. p. 94.

Nv

NI Dum fw

. Scyelite, Achavarasdale Moor, Caithness. Quart. Jour. Geol. Soc. 41,

p- 402.

. Wehrlite, Red Bluff, Gallatin Co,, Mont. C, & H. p. 140.
. Lherzolite, Johnny Cake Road, Baltimore Co,, Md. R. 165.
. Saxonite, Douglas Co., Oregon. C, & H. p. 231.

Cortlandtite (Schillerfels) Schriesheim, Odenwald, Hesse. R. p. 165.
Bronzite Diallage Peridotite, Howardville, Md, Bull. U.S. Geol. Survey,
Now28,) p54:

. Dunite, Dun Mts., New Zealand. R. p, 165.

9. Dunite, Elliott €o., Ky. C. & H. p. 93.

ut

Rare Rock Types

. Rockallite, Rockall Bank, Atlantic. Geol. Mag. (4) 6, p. 165. 1899.
. Basic Nephelene-Syenite, Beemerville, N. J. Trans. N. Y. Acad. Sci. 11,

p. 86.

. Urtite, Lujaur Urt, Kola Peninsula, Russia. Geol. Féren, Forh, 18, p.

462. 1806.

. Ijolite, liwaara, Finland, and Umptek, Kola Peninsula, Russia. /dzd.

13, p. 300. 1891.

. Missourite, Highwood Mts., Mont. Am. Jour. Sci. (4) 2, p. 315. 1896.
. Dunite, Elliott Co., Ky. Bull. 38 U.S. Geol. Survey, p. 24. 1887.

WM. H. HOBBS

28

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a

DENTITION OF SOME DEVONIAN FISHES

DurING the last few years our knowledge of the multiplicity
and relationships of the Middle and Upper Devonian fish-faunas
in this country has been enlarged by the discovery of much new
material. Exceptionally interesting finds have been made in
the Marcellus, Hamilton, and Naples shales of New York, the
Chemung-Catskill of Pennsylvania and its presumable equivalent
in Johnson county, Iowa, in the Corniferous of Ohio, and in the
Hamilton limestone of Wisconsin and adjoining states. From
-the last-named horizon notable collections have been brought
together and rendered accessible for study by Messrs. E. E.
Teller and C. E. Monroe and the late T. A. Greene of Milwaukee,
and Professors Calvin and Udden of the Iowa State Geological
Survey. These have been freely drawn upon in the preparation
of the following notes.

GENUS DINICHTHYS, NEWBERRY

So intimately related are the two best-known Arthrodires,
Coccosteus and Dinichthys, that the only crucial test of generic
distinctness is afforded by the dentition. Likewise, for the
discrimination of species, dental characters are all-important.
Among the body-plates the chief distinctive characters are fur-
nished by the dorso-median and clavicular.

1. D. pustulosus E. (Fig. 1).— Although remains of this
Hamilton Dinichthyid are tolerably abundant, nothing was
known of its dentition until recently, when one large premax-
illary, nearly equaling that of D. ¢errelli in size, and two max-
illary or shear-teeth were found by Mr. Teller in the hydraulic
cement quarries of Milwaukee. Last falla fragmentary mandible
showing rudimentary denticles along the posterior slope of the
cutting edge was obtained from the Hamilton of New Buffalo,
Iowa, by Professor Udden, and still more recently Mr. Monroe

32

DENTITION OF SOME DEVONIAN FISHES 33

was fortunate enough to secure at the typical Milwaukee locality
the specimen shown in Fig. 1.

The inner face of this specimen is attached to a block of
limestone, a part of the anterior extremity is broken away, and
a considerable portion of the posterior end is missing. The
total length may be estimated at about 24°, the proportions
being about the same as in D. curtus, and about three quarters
the size of an adult individual of D. zntermedius. The posterior

aus)

Fig.1. Dinichthys pustulosus E. Hamilton; Milwaukee, Wisconsin. Left mand-
ible Ge.

end is more slender than in either of these species, and the cut-
ting edge also differs in having no prominence back of the tooth-
like beak. The cutting edge of D. intermedius has one such
prominence, and that of D. curtus two. In D. curtus ‘the posterior
end of the cutting edge is set with two or three unequal denticles
in place of the series of even, lancet-like points in the same
position on the mandible of D: tntermedius.”’* But in the present
form these denticles are reduced to mere swellings, of which five
may be counted along the posterior slope of the cutting edge.
Professor Udden’s specimens, altho smaller, shows the bosses
more prominently; they are, in fact, rudimentary denticles, and
represent the initial stage of those structures which are such a
conspicuous feature in D. herzeri of the Ohio Shale.

* NEWBERRY, J. S., Pal. Fishes N. A. (Mon. U. S. Geol. Surv., Vol. XVI, p. 156),
1889.

34 C. R. EASTMAN

_ The cutting edge of the mandible is beveled to a sharp
edge, and shows the usual indications of wear. It belonged to
an average or slightly undersized individual, judging from the
proportions of a dozen crania that have been found at Milwau-
kee. The largest of these, it should be noted, is only one fifth
smaller than an averaged-sized head of D. terreli. The premax-
illaries and shear-teeth do not call for any special comment,
except that the latter are without denticles on the posterior
margin. —

2. D. halmodeus (Clarke).—The presence in the type speci-
men of functional premaxillary teeth, and of a carinal process
on the under side of the dorso-median, are sufficient reasons for
transferring this species from Coccosteus to Dinichthys. The
_~mandibles, which measure about 6.5™ in length, have in place of
a cutting edge a series of seven or more backwardly directed
denticles. The anterior beak is missing in both mandibles, and
the premaxillaries are also damaged. The latter are relatively
very powerful, and provided with an elongated base for attach-
ment to the visceral surface of the cranium. The plates desig-
nated as 2, mx, pmx, and fio, in Dr. Clarke’s diagram®* are all |
parts of a single element, the suborbital. Examination shows
that the cranial osteology and structure of the dorso-median are
normal in every way.

3. D. herzert Newb.— This species is commonly supposed to
be limited to the Huron Shale, but it probably had a continuous
range from base to summit of the Ohio Shale. Its occurrence
in the Cleveland Shale may be strongly suspected, if indeed it is
not proved by two specimens described by E. W.Claypole. The
first is the fragmentary mandible known as D. keplert Cl.,? and
the second is the series of massive plates (plastron and clavicu-
lar) preserved in the Ohio State Museum, and figured in part in
Vol. VII of the Ofzo Geological Survey Reports (P\. XX XVIII-XL).
The clavicular and postero-ventro-median each have a length
of aboute50™, and the postero-ventro-laterals are over 76°™

* Thirteenth Ann. Rep. State Geol. N. Y., Vol. I, 1893, p. 162.

2Amer. Geol., Vol. XIX, 1897, p. 322, Pl. XX.

DENTITION OF SOME DEVONIAN FISHES 35

long, indicating a creature about two fifths larger than the aver-
age of D. ¢errel. Believing these proportions too large for any
known species of Dinichthys, Claypole* referred the remains to
Titanichthys ; and later the name of D. ingens was suggested for
them by Wright.* We propose to cancel both this title and that
of D. kepleri in favor of the type species of Dinichthys. Other
plates of huge size belonging in all probability to the same species
are preserved in the museum of Kentucky State University at
Lexington.

4. D. clarki (Claypole).—A large species of Dinichthys allied
to the preceding, so far as may be judged from the dentition,
was made the type of a new genus by Claypole,3 and named by
him Gorgonichthys clarki. No characters are shown, however,
which warrant a separation of this form from Dinichthys; on the
contrary, the mandible displays an interesting stage of modifica-
tion between denticulated forms like D. herzeri, D. halmodeus,
etc., on the one hand, and those with a sharp cutting edge like
D. terrell on the other.

The type of the so-called ‘‘Gorgomchthys’’ and the large
premaxillary described by Claypole* as Dimchthys clarki have, of
course, nothing in common. The relations of the latter are not
accurately determinable. If excluded from Dimichthys, a new
generic name will be required; if retained, a new specific name
is necessary.

GENUS CLADODUS, AGASSIZ

This typically Carboniferous genus occurs sparingly in the
Neodevonian, but no species have been reported from Mesode-
vonian horizons. That it was present, however, in both the
Corniferous and Hamilton periods is proved by at least two
specimens which have come under the writer’s observation. One
of these is a large tooth from the Corniferous limestone of
Columbus, Ohio, now preserved» in the American Museum of

* Rep. Ohio Geol. Survey, Vol. VII, 1893, p. 611.

2 Bull. Mus. Comp. Zodl., Vol. XXXI, 1897, p. 24.

3 Amer. Geol., Vol. X, 1892, p. I.

4 Jbed., Vol. XII, 1893, p. 278.

36 Cen eA SULA

Natural History in New York (Cat. No. 4257). Although very
similar to C. striatus Ag., it probably belongs to a distinct species.

C. monroet, sp. nov. (Fig. 3) —The type of this species is a
small, imperfectly preserved tooth found by Mr. C. E. Monroe
in the Hamilton of Milwaukee. The drawing reproduced here-
with is made up from both halves of the counterpart containing
the specimen. Traces of striae appear in places, but are nearly

j
|
|
|
|
|

2

Fic. 2. Cladodus monroei sp.nov. Hamil- Fic. 3. Supposed cone-scale from Kinder-
ton limestone; Milwaukee, Wisconsin. hook fish-bed at Burlington, lowa. X 2.
x7:

obliterated by decay of the enamel and dentine, and portions of
the crown and base are broken away. The crown is robust,
being very thick at the base, and the external denticles are pro-
portionately stout. Three cusps of small size intervene on each
side between the principal cone and external denticles. The
total height may be estimated at about 1.3, and the width of
base at 2aS irae

Other Corniferous forms occurring in the same horizon at
Milwaukee are teeth and plates of Onychodus, spines of Machaer-
acanthus, and Chimaeroid remains. Macropetalichthys and Aster-
osteus, however (which on account of their cranial osteology and
lack of dentition we must now exclude from Arthrodira and
place with the Ostracoderms as degenerate Elasmobranch off-
shoots), are conspicuously absent.

DENTITION OF SOME DEVONIAN FISHES 37

GENUS D/PTERUS, SEDGWICK AND MURCHISON

There are two distributional centers for this genus in America,
between which there was apparently no communication. In the
eastern province, which includes the Chemung-Catskill of New
Yorkand Pennsylvania, it is associated with forms common to the
Upper Devonian of Canada and Europe. In the western province
(Iowa and Illinois to Manitoba) it ranges from the base of the
Hamilton to near the top of the Devonian and is accompanied
by Ptyctodus and a number of Dipnoan forms peculiar to this
region." Here are found no traces of Crossopterygians or Ostra-
coderms; in fact the western Neodevonian fish-fuana is entirely
distinct from the eastern, and represents a different migratory
movement.

The Chemung proper contains but two well-recognized
species of Dipterus, D. flabelliformis and D. nelsoni, the latter
including Newberry’s so-called D. devs (founded on worn speci-
mens), and possibly D. quadratus and D. minutus. From the
Catskill of Pennsylvania four species are known: D. sherwood,
D. fleischert, D. angustus and D. contraversus (=D. radiatus N.).
Several of these species are founded on imperfect material, and
the original descriptions require emendation, To this list may
now be added four new species from the Middle and Upper
Devonian of Iowa, the types of which are preserved in the
Museum of Comparative Zodlogy at Cambridge, Massachusetts.

1. D. uddeni, sp. nov. (Fig. 5).—This species is established
on a unique mandibular dental plate from the base of the Cedar
Valley limestone (Middle Devonian) near New Buffalo, lowa.
It has a total length of 36™™, is moderately convex, and remark-
able for the paucity of its denticulated ridges. These are only
four in number, and radiate in gently curved lines from the
posterior angle, which is worn smooth by use. The anterior
row of denticles and inner moiety of the remaining rows are
also considerably worn; but in the outer moiety of these rows
the denticles are acutely conical, of large size and well separated.

* Ann. Rep. Iowa Geol. Surv., Vol. VII (1896), Pl. IV; zézd, Vol. IX (1898), p. 302 ;
Jour. GEOL., Vol. VII (1899), p. 77.

38 C. R. EASTMAN

There is a progressive diminution in size of all denticles pro-
ceeding posteriorly. The coronal surface is finely punctate.
This beautiful dental plate is the oldest of all Depterus remains
that have been found in this country. It was discovered by
Professor J. A. Udden of Augustana College, Rock Island, in

Fic. 4. Diplerus costatus sp. nov. Upper Devonian ; Johnson county, lowa.

Fics. 5, 5%. Dipterus uddeni sp. noy. Cedar Valley limestone; New Buffalo,
lowa.

Fics. 6, 8. Dipterus mordax sp.nov. Upper Devonian; Johnson county, Iowa.

Fic. 7. Dipterus calvinit sp. nov. Cedar Valley limestone ; Fairport, lowa.

whose honor the specific title is dedicated. A note of its geo-
logical occurrence was published in the August number of this
JouRNAL (p. 494) for last year.

2. D. calvini, sp. nov. (Fig. 7).—Like the last, this species
is founded on a unique dental plate (right mandibular) from the
Cedar Valley limestone of Iowa. It comes from a higher level,

DENTITION OF SOME DEVONIAN FISHES 39

however, having been found by Professor Udden in the so-called
‘“Kuomphalus bed” at Fairport, Muscatine county, which lies
about eight feet below the summit of the Cedar Valley limestone,
or Hamilton of Worthen and others.

The plate is elliptical in outline, and moderately convex in
an antero-posterior direction. Eight tuberculated ridges extend
from the outer margin to about the center of the plate, the two
anterior ones being the largest and elevated into a slight fold.
Coronal surface considerably worn, and external margin partially
broken. Tubercles conical and well separated, except those of
the two anterior ridges, which are coalesced and worn on their
summits. Total length of plate 3°". Named in honor of Pro-
fessor Samuel Calvin, State Geologist of Iowa.

3. D. costatus, sp. nov. (Fig. 4).—This plate agrees in size
and general outline with D. calvini, but it has fewer and more
widely separated coronal ridges which disappear before reaching
the center of the plate. The distinguishing feature of this
species consists in the elevated sharp ridge extending along the
entire length of the inner margin, and separated from the
remaining tuberculated ridges by a broad longitudinal furrow.
This ridge appears to be of compound origin, or made up of
three coalesced costae, of which the third counting from the
inner margin is the largest. The two innermost costae are so
faint as to be almost imperceptible on the steep face of the
main ridge. The summit of the latter is sharp, and shows no
evidence of being made up of tubercles. The tubercles of the
five marginal ridges are also worn nearly smooth and more or
less coalesced. But for the convexity (in a longitudinal direc-
tion) of the coronal surface this might be taken for an upper
dental plate. Several examples of this form have been obtained
from the State Quarry fish-bed near North Liberty, in Johnson
county, lowa.

4. D. mordax, sp. nov. (Figs. 6, 8).— Dental plate attaining
a length of over 3°", coronal surface gently convex, with six
rows of very large, well separated conical or rounded tubercles
which extend from the outer margin for a variable distance

40 Os Lit LIAS HATLAIIN,

toward the posterior angle; the two posterior rows often rudi-
mentary. Some of the tubercles, when worn by use, become
elongated in the direction of the rows to which they belong, and
others in an oblique direction. This species is readily distin-
guished from all others previously described by the relative
coarseness of its tuberculation. It is represented by a number
of examples from the State Quarry beds of Johnson county,
Iowa.
NOTICE OF PROBLEMATICAL ORGANISMS

Some thirty years ago Mr. Orestes St. John, when assistant
in the Museum of Comparative Zodlogy, collected a number of
Selachian teeth and spines and some large Dinichthyid plates
from a ‘‘fish-bed”’ near Burlington, lowa, supposed to be near
the dividing line between Upper Devonian and typical Kinder-
hook. Small spines of Stethacanthus, Erismacanthus, and Homa-
canthus are rather abundant at this locality, also dermal tubercles
of sharks. From the upper part of the formation Mr. St. John
obtained the carapace of a Schizopod crustacean, and also some
vegetable remains, such as branches of a Lepidodendron and
woody fibers. In addition he found a number of peculiar fossils
of which the one shown in Fig. 2 is a fair example, and within
the past year other specimens of the same sort have been col-
lected by Professor Udden in the Kinderhook near Burlington.

An examination of the latter forms by Professor Arthur
Hollick of Columbia College leads him to the opinion that they
are cone-scales of some conifer probably allied to Avaucaria.
A figure is given herewith for the benefit of those interested in
the study of Mississippian faunas.

EXPLANATION OF VEIGUIRISS

Fic. 1. Dinichthys pustulosus E. Hamilton limestone; Milwaukee, Wis-
consin. Left ramus of mandible. x 2.

Fic. 2. Cladodus monroei sp. nov. Hamilton limestone; Milwaukee,
Wisconsin. 2. é

FIG. 3. Supposed cone-scale from Kinderhook fish-bed at Burlington,
Iowa. X =.

DENTITION OF SOME DEVONIAN FISHES 41

Fic. 4. Dipterus costatus sp. nov. Upper Devonian; Johnson county,
Iowa. Left lower dental plate.

Fies. 5, 5%. Dipterus uddent sp. nov. Cedar Valley limestone; New
Buffalo, Iowa. Left lower dental plate, oval surface and profile.

Fic. 6, 8. Difterus mordax sp.nov. Upper Devonian; Johnson county,
Iowa. Somewhat worn examples of right lower dental plates.

Fic. 7. Dipfterus calvint sp. nov. Cedar Valley limestone ; Fairport,
Iowa. Right lower dental plate.

| Figs. 4-8 reduced slightly less than natural size. ]

C. R. Eastman.

ANCIENT ALPINE (GLACIERS, OF SEEIE Sit RRA COSI
MOUNTAINS IN CALIFORNIA

INTRODUCTION

NORTHWESTERN California is a vast complex of mountains,
forming the Klamath system, whose geological features are
similar to those of the Sierra Nevada range. Centrally situated
within it is a series of high granitic and syenitic peaks, consti-
tuting the range of the Sierra Costa Mountains. Beginning in
Castle Crag, about fifteen miles southwest of the lofty volcanic
peak of Mt. Shasta, they trend thence southwestward about fifty
miles, with an average width of between fifteen and twenty
miles. Within this territory of eight or nine hundred square
miles there are a score or more of bare, ragged peaks rising to
altitudes of 7200 to 9345 feet above the sea. Between them
are deep, narrow valleys whose floors have altitudes between
2500 and 6500 feet, averaging about 4000 feet. Some of the
more elevated of these present distinct evidences of past glacia-
tion. The glaciers were very localized in development, never
coalescing to form a general glaciation of any part of the terri-
tory, and hence the glacial phenomena displayed in these moun-
tain valleys are characteristically different from those of the
drift-covered regions of the Mississippi basin.

GENERAL DESCRIPTION OF THE GLACIAL PHENOMENA

There is a radical difference in topography between the
glaciated and non-glaciated valleys. The latter are V-shaped
gulches with steep straight slopes and a width at the bottom often
but little greater than that of the stream flowing within them.
In places they are very rocky, with jagged ledges projecting
from their sides. All the stony material found on their slopes
is of the rock species underlying the soil on each particular
slope. The same valley, traced up to where it once possessed a
glacier, will rather abruptly change its form to a broad and

42

GLACIERS OF THE SIERRA COSTA MOUNTAINS 43

open U-shaped trough, with smooth and curved slopes, and a
gently rounded floor. This change has been effected by a
grinding away of the talus material and solid rock along the
middle levels of the slopes and a filling of the extremely narrow
lower portion of the gulch. The ravines have been destroyed,
partly by filling and partly by the grinding away of the inter-
vening ledges. Often this smoothing of the contours has
extended up toa certain level, above which the mountain sides
are deeply scored with ravines, and jagged with outcropping
ledges.

Most of the valleys present but a moderate amount of ground-
moraine, altho the lateral moraines are well developed. The
glaciated slopes are abundantly supplied with bowlders of all the
rock species occurring from thence to the head of the valley.
They are embedded in a loose agglomeration of subangular
gravel, sand and a little clay, forming a deposit quite unlike the
till of the Mississippi basin, altho somewhat more nearly resem-
bling the very stony moraines of New England. These lateral
moraines are smooth in outline, rarely displaying a hummocky
topography, and only in a few cases standing out distinct from
the mountain ridges. In the unglaciated gulches, especially
‘where the country rock is serpentine, extensive land slips are
resting on the lower slopes, and they present a hummocky
topography almost identical with that so characteristic of glacial
moraines in the Mississippi basin, even to the extent of possess-
ing kettle-holes containing lakelets. These must not be con-
founded with the lateral moraines.

Lines of erratics perched high on the mountain sides some-
times indicate the maximum altitude of the glacial action. From
the smooth curved slopes of the lateral moraines, low narrow
ridges of very stony material trend obliquely toward the center
of the valley, those on opposite sides forming a loop, pointed
downward. Sometimes they coalesce and are then cut by a
small canyon-shaped valley thru which the stream finds an outlet
from the enclosed basin above. These are the only representa-
tives of true terminal moraines (being formed at successive

44 OS GAT VEL ee SLY

stages of readvance during the general recession of the gla-
cier), but are quite insignificant as compared with the lateral
moraines.

Near the heads of the glaciated valleys the rock surface is
often bare over thousands of square feet, and is then seen to be
smoothed and rounded by the grinding action of the ice. Some
distinct grooves appear, but are not common. Of more frequent
occurrence are fine lines or striz, altho where long exposed
these have been destroyed by weathering.

By far the most characteristic of the glacial phenomena of
the Sierra Costa Mountains are the high meadows and lakelets.
The former are smooth expanses of the valley floor a mile or
more in length by half as great width, occurring near the heads
- of the valleys. They are inclined to be damp and boggy, and
are grassed, instead of timbered and brushy, as other portions of
the mountain region. They are underlaid with a fine gravelly
silty ground moraine, and over their surfaces are frequently
scattered large erratics of an englacial and superglacial mode of
transportation. The lakelets are rounded bodies of clear cold
water, varying from a fraction of an acre to twenty or more
acres in extent, sometimes occupying rock-bound basins of gla-
cial origin, but generally held in behind moraines. Around the
border may be a tiny beach of white sand, or a narrow strip of
flat, grassy land composed of black peaty soil. Some of these
tiny mountain tarns are perched high up on the mountain sides
in small coves or niches abraded from the solid rock by the
downward pressure of the ice under the névés. A few of these
coves are hundreds of feet in depth, have steep, often precipi-
tous, rock-walls, and are nearly closed in by the surrounding
ridges so that they closely resemble the cevques of the Alps.

An especially favorable situation for the glacial lakelets is at
the foot of high rock precipices which usually occur onthe southern
or western sides of the valleys. The glaciers invariably hugged
the shady side of the valleys and there accomplished their most
active grinding work. It was on the northern side of the frown-
ing peaks that the ice laid longest, and when its final melting

GLACIERS OF -THE SIERRA COSTA MOUNTAINS 45

was accomplished, depressions were left at the foot of the preci-
pices which had been produced by the removal of the talus
material and some of the solid rock. In several cases one may
stand on a high peak and throw a stone so that it will drop into
the clear water of a lakelet, 1000 feet below. These high preci-
pices are another characteristic of the glaciated valleys, for they
never occur elsewhere in these California mountains.

The glaciers headed in valleys whose altitude is now between
6500 and 7500 feet above the sea, and descended to 5000 or
5500 feet (with two notable exceptions). Thus the declivity
of the glaciated valleys is great; but the descent is effected by
a series of terraces or steps, gentle slopes alternating with steep,
almost precipitous, sections where the valley floor is rapidly let
down 100, 200 or even as much as 500 feet vertically. These
““steps’’ are only in small part due to moraines, being composed
mainly of solid rock. Over them the glaciers cascaded, forming
extensive crevasses, then coalescing into a solid mass and mov-
ing along smoothly a mile or more to the next cascade. Toward
the close of the ice period, when the main glaciers had shrunk
to insignificant remnants, tiny glaciers continued to issue from
under the local névés in the coves high up on the mountain sides,
and cascaded over precipices as much as 500 feet in height.

I have mentioned a sufficient number of the features of these
valleys to place it beyond doubt that they have suffered glacia-
tion in some past period, and to demonstrate that the glacial
action was essentially identical in character with that at present
obtaining in the high Alpine valleys of Switzerland.

CHARACTERISTIC FEATURES OF INDIVIDUAL GLACIERS

The Castle Creek glaciey.— At its maximum extension, this
glacier had a length of about two miles, a width of one quarter
to one half mile and a depth of 500 to 800 feet. It was situated
at the northern foot of Tamarack peak, near the junction between
Trinity, Shasta and Siskiyou counties. The present altitude is
about 6500 feet. Within the limits of its site are six pretty lake-
lets, one lying at the foot of a 1000-foot precipice. The glacier

46 OSCAR H. HERSHEY

flowed in an easterly direction and hugged the southern side of
the valley, there leaving the rock bare of talus or morainic
material. In receding, it melted away from the warm northern
side of the valley, and left several successive lateral moraines on
the valley floor, running lengthwise of it. The last of the series
is about in the center. A trough shaped depression occupying
the southern half of the valley indicates the final track of the
dying glacier.) Init lies some ot gthe wlalelets: | VAN tmibubaigy,
glacier entered the main trunk at nearly a right angle, and cas-
caded over a rock-ledge now 500 feet above the main valley
floor. The ledge is smoothed and striated. Above it a lakelet
is held behind a moraine composed of clay, sand, gravel and
bowlders, some of which are beautifully striated. The interest-
ing feature of this glacier was its evident sensibility to the sun,
“causing it to melt away from the sunny side of the valley long
before it disappeared from within the shadow of Tamarack peak.

The Salmon River glacier—This was seven miles in length,
one half to one mile in width and 1000 to 1500 feet in depth.
Its course was a little east of north. It headed at about 6500
feet of altitude (present), and descended but little below 5500
feet. On the west of its upper half was the high granite peak
of Mt. Courtney, whose slope is now bare of loose rocks and soil
from summit to base and is worn smooth and rounded by glacial
abrasion. From the precipitous pinnacles of the sawlike crest,
huge bowlders of granite crashed down upon the ice, and now
lie scattered upon the floor of the valley and even over the
opposite slope. Several are as large as an average miner’s cabin.
Beyond the granite of Mt. Courtney, where the rocks are mainly
hornblende and mica schists, the upper limit of the glacier is clearly
defined high on the mountain sides by a sharp line below which
granite bowlders are numerous and above which there are none ;
also, by shoulders or small precipices on the inter-ravine spurs
of the mountain on the east, showing to what height the glacial
abrasion extended.

Many prospectors and semi-scientific observers have noted
the fact that the upper four or five miles of the original main

GLACIERS OF THE SIERRA COSTA MOUNTAINS 47

Coffee Creek has been beheaded and added to the South Fork
of Salmon River, but not many have clearly discerned that this
was due to glacial action. In ascending the Upper Coffee Creek
valley, after the great bend is passed, the floor widens to quite
a plain, there being here a heavy filling of waterlaid gravel and
sand, the extra-glacial deposit of the glacier above; on this, at
the mouth of each tributary gulch, there is a beautiful alluvial
fan. About one and one half miles below the head of the creek,
a slight ridge crossing the valley and carrying granite erratics
marks the extreme limit of the glacier. From here to the sum-
mit stretches the ‘“ Big Flat,” a smooth plain of fine gravel
and sand (with scattered granite erratics) about one and one
half miles in length and one half mile in width. At its upper
end (which is the summit of the Sierra Costa Mountains, the
water-parting between the main Klamath and the Trinity River
systems, and the Trinity-Siskiyou county line) there is the
slightest tendency to a morainic character. This ‘“‘ Big Flat”’
has an altitude of 5500 feet while the mountains on either hand
rise to 7000 and 7500 feet. Here the glacier made a filling sev-
eral hundred feet in thickness, thus obstructing the valley. At
the same time it wore the rock wall of the valley on the west
(which had already been nearly cut thru by the head water
erosion of the original South Fork of Salmon River) so thin that
a glacial stream crossed the ridge in a col and soon cut down
a gorge. Hence it is that the South Fork of Salmon River rises
in the head of the original Coffee Creek valley, follows it for
four or five miles until within a few hundred yards of the present
head of Coffee Creek, then turns to the west at a right angle,
and passing out of the broad valley thru a narrow gorge where
it abounds in rapids and falls, it makes its way thru unglaciated
gulches to the Klamath. This is one of the finest examples of
the beheading of a stream by glacial action that I know of.

As indicated by the granite erratics, the surface of this
Salmon River glacier descended 1000 feet (and the glacier
thinned to that amount) in the last one and one half miles of
its course.

48 ONC Ale Jal, JaldlceSwale, JC

Within several miles of its head, the South Fork of the Salmon
River has carved a pretty postglacial gorge or tiny canyon in
the solid rock of the old valley floor. This is twenty to thirty
feet in depth, has precipitous walls, and is no wider than the
small stream flowing in it. It abounds in rapids and low
cascades.

The Union Creek glacier.—This occupied the next main series
of high valleys to the east of the Salmon River glacier. There
was a main trunk five miles in length, and two branches each
several miles in length. The width was one quarter to one half
mile, and the thickness of all approximated 1000 feet. They
headed at about 6500 feet (present altitude), and the main
trunk descendeds to) 5000) feet of saliitiudes NeamaitsmenGesin
‘was much contracted, and but little modified the original
V shape of the valley. Its extent is clearly defined by its very
bowldery lateral moraines. One of these partly obstructs the
mouth of a tributary valley, that of Pin Creek, which was not
glaciated, altho equally as elevated as glacier occupied valleys
on either side of it. This was because it opened too directly
toward the sun.

When recession had proceeded to the extent of dissevering
the branches of the glacier in the East and West Union Valleys,
that of the East Union was the most vigorous, and formed a
beautiful half-looped terminal moraine at the junction. The
West Union Creek flows swiftly in a shallow ditch cut into the
very bowldery deposit just outside of the crest of the moraine,
but transverse to the general slope of the surface. This shows
that this creek occupied its present course as early as the
time when the moraine limited the East Union glacier. The
extremely small amount of erosion accomplished on this steep
declivity tells of the recency of the glacial epoch in these
mountains.

The three Unions have the usual meadows, and are well
supplied with glacial lakelets.

The Swift Creek glacier—The characteristic features of this
member of the glacial series were its length, its descent to a low

GLACIERS OF THE SIERRA COSTA MOUNTAINS 49

altitude, its heavy ground moraine, and its beautiful terminal
moraine.

At its maximum extension, this glacier had a length of not
less than fifteen miles, a width of one half to one mile, and a
depth of 1000 to 1500 feet. It was the largest single mass of
ice, so far as I know, of the Sierra Costa Mountains. It headed
among the peaks in the highest portion of this range, at an alti-
tude now about 6500 feet, trended in an easterly direction,
forming the broad flat of the Mumford meadows (altitude 5500
feet), then ran southeasterly, descending rapidly to a level now
little more than 3500 feet above the sea, where at ten miles
from its head, it suddenly issued from the high mountains, and
turning to the northeast, it deployed upon and across a broad
basin valley of Miocene age and later, and terminated very close
to the site of the Redding and Trinity Centre road at an eleva-
tion now no greater than 2500 feet above the sea. Here are,
so far as I am aware, the least elevated direct glacial deposits
west of the Sacramento River, if not in the whole state of
California.

Among the prospectors of northern California, the “‘cemented
gravel of Swift Creek” is a term to conjure with. It is essen-
tially non-gold-bearing, and so far as the ability of the average
miner to sink a shaft through it is concerned, it is bottomless.
It is an unstratified agglomeration of bowlders, cobbles, pebbles,
sand, silt, and clay, which occupies the valley from head to
mouth, forms the flats or meadows, and is trenched by a narrow
canyon carved by Swift Creek in postglacial time. Where the
stream, in undermining a bank, has made a recent excavation,
the deposit has an extremely fresh appearance and a delicate
light bluish tint. Many of the included bowlders are rounded
and polished, and not a few are beautifully striated. It is as
typical a till as any tobe found on this continent. Being largely
the result of glacial abrasion on the rock floor and walls of the
valley (serpentine mainly), it is slightly cemented by the large
constituent of unoxidized magnesian and calcareous salts. Most
of the included rock fragments are serpentine of the black

50 OSNGAI Jals Jal EI S/aG NC

amorphose variety, and the light oil-green schistose variety, and
the blue tinting was derived from the grinding of this formation.
It cannot be worked for its included gold asa placer deposit,
because there has been no concentration of the precious metal
by water action as in ordinary stream alluvium.

This fine deposit of subglacial till or ground moraine attains
its fullest development about midway of the course of the
glacier where it must have a depth in places of not less than
several hundred feet. At an altitude of about 5000 feet, the
most prominent glacial features cease. Beyond this the valley
contracts and descends rapidly over a series of high steps, which
are strewn with a profusion of bowlders, some of which are
striated. Everything here is confusion—there may be indis-
_ tinct terminal moraines, lateral ridges, voches moutones, and some
ground moraine, but the best expert cannot get much regularity
out of the piles of bowlders heterogeneously distributed along
the slopes of the bounding mountains and on the irregular
valley floor. Here the creek descends rapidly in one long
series of rapids and cascades, along its bowlder strewn bed, and
in one place has cut a beautiful gorge thru the solid serpen-
tine rock. It is several hundred feet in length and thirty to
fifty feet in depth, and no wider than the stream. With its
perpendicular and even overhanging walls, it is a veritable
canyon. It abounds in remolinos (pot-holes) whose mode of
formation can plainly be seen, from the clearness of the water.

When the Swift Creek glacier issued from the deep valley in
the high Sierra Costa Mountains and deployed across the
Miocene basin, it did not spread out as an alluvial delta, but it
maintained its narrowness to the end, five miles distant. Around
this extra-montane portion it formed a beautiful moraine. The
constitution of this is essentially similar to that of the cemented
gravel farther up the creek, except that it contains less clay, is
looser and coarser in texture, and has some large erratics on its
surface. Where trenched by tributary creeks and its interior
freshly exposed, polished and striated pebbles and bowlders are
not difficult to find. Two parallel ridges of about equal height,

GLACIERS OF THE SIERRA COSTA MOUNTAINS SI

and even crests, trend from the sides of the mouth of the upper
valley northeastwardly across the Miocene basin, gradually
descending toward Trinity River. Between them is a flat-
bottomed, steep sided depressed area, 300 to 500 feet in depth
and one half mile in width, evidently representing the cross-
section of the glacial tongue. From the crests of the ridges
more gentle slopes of very bowldery land extend outward and
gradually merge with the erosion surface. These ridges are the
extra-montane extensions of the lateral moraine, but also con-
tain ground moraine and may be considered a terminal moraine.
Near the Trinity River they flatten down, become hummocky
and indistinct, but appear to curve around the end of the site of
the ancient glacier and connect, except for the postglacial
canyon which the stream has cut thru the moraine. Beyond this
is a fine example of a fan-shaped extra-glacial delta, which occu- .
pies several square miles in the valley of the Trinity River, and
its outer edge descends almost. to the level of that stream itself.

This glacial tongue reached the northern end of the low
Minerva range of mountains, and built its moraine across the
mouths of several of the gulches. These have been filled nearly
to the level of the moraine summit by fine silts, and form
extensive grassy flats composed of deep black soil free from
pebbles. Along the moraine the flats have some large angular
erratics on their surface; these have slidden from the surface of
the glacier.

In the bottom of the depressed area within the moraine Swift
Creek has eroded a canyon 75 to 150 feet deep and 300 to 500
feet wide, widening and shallowing toward the mouth. This seems
large, but represents glacial as well postglacial stream erosion.

On the whole, the glacial features of the Swift Creek valley
are extremely interesting and instructive, and, from its accessi-
bility, should become classical among students of California
Quaternary geology.

The East Fork glacier—This occupied a high valley, steeply
descending on the east face of Granite Peak, a few miles north-
west of Minersville. Near its head a precipitous mountain side

52 OSCAR 7. HERSHHEMV

shows the smoothing and rounding action of the glacier up toa
certain height, above which the bare rock is extremely rough
and jagged. Some glacial grooves are seen and a little striation.
In another place there is a well-defined line of perched erratics.

This glacier also issued from the high mountains, and it cut
directly thru the old Miocene river channel, carrying its huge
granite bowlders nearly or quite to the Minersville-Trinity
Centre road, terminating at a point probably now no greater than
3000 feet of altitude. Itis a well-known fact that all the gulches
which are cut into this old Miocene channel deposit have been
rich in placer gold, except the valley of the East Fork, which
cuts directly thru it, and yet never paid to work. The apparent
anomaly is explained when it is understood that the East Fork
glacier ground all of the gold-bearing alluvium out of the valley
, and left in its place its own only slightly auriferous deposit —
the glaciated valleys are never worked as placers.

Quite a number of other valleys in the Sierra Costa Moun-
tains were once occupied by glaciers. The presence of a number
of lakes (as mapped) in the deep canyons south and east of Mt.
Thompson of the granite Cariboo range seem to indicate that a
cluster of them occupied that region. Probably a score or more
existed in Trinity county alone; but the examples given in this
paper are typical of them all, and will suffice for the purposes of
the present study.

AMsis, AVES, (ON ANSUS, (CILACINTINS)

At one time I thought I had detected evidences of two glacial
epochs in the Sierra Costa Mountains, one very recent and
another much older, but I have had to revise this opinion. The
deposits near the lower end of the glaciated valleys are of
slightly more aged appearance than those near the heads, but
the contrast is not great. They are essentially a unit, so far as
age is concerned.

The weathering of the once striated, polished, and perfectly
smoothed rock surface, the erosion of small canyons in the rock-
floors of several of the glaciated valleys near their heads, and

GLACIERS OF THE SIERRA COSTA MOUNTAINS 53

the peaty accumulations about the borders and on the bottoms of
the lakelets show that the glaciation has not just terminated —
the ice has been completely gone for at least several thousand
years. Yet the many lakelets held behind frail barriers of till,
the cascades and rapids, and the generally uneroded condition
of the drift tell, in unmistakable terms, of the comparative
recency, geologically speaking, of the glaciation. Subaerial
erosion, aside from one main stream channel in each valley, has
been practically nothing. Even the excavation of the single
central canyon was largely accomplished while the ice yet lin-
gered in the heads of the valleys, and by its rapid melting greatly
increased the streams. With the steep declivities and the heavy
annual precipitation, it is remarkable how little erosion has been
accomplished in northwestern California since the glacial epoch.
Certain cemented river gravels in the valleys of the East Fork of
Trinity River, the main Trinity River, and lower Coffee Creek,
which represent the outflow from the glacier, rest upon the lowest
bedrock in these valleys, and the canyons since excavated in them
are quite insignificant. Glaciation was one of the very latest
events in the northern California valleys. That it was of late
Quaternary age requires no argument.

The beautiful sky-blue till of the Swift Creek valley has a
freshness which may be likened unto that of the Wisconsin drift-
sheet in the Mississippi basin, and oxidation of its surface portion
has not proceeded to any greater depth. Indeed, the youthful
appearance of the whole series of glacial phenomena is identi-
cal with that which has come to be associated in my mind with
the Wisconsin drift sheet. J am certain that this Sierra Costa
glaciation was not the age equivalent of the Iowan or any earlier
drift sheet. I am equally as certain that the glaciers disappeared
a sufficient length of time ago to carry the glaciation back to the
Wisconsin epoch. If there were two Wisconsin glaciations in
the Mississippi basin, as some glacialists seem inclined to con-
clude, this California glaciation represented the later. At any
rate, the glaciers. of the Sierra Costa Mountains certainly were of
Wisconsin age.

54 OSCAR HV HERSH EY:

DISCUSSION OF CLIMATIC CONDITIONS DURING GLACIATION

It goes without saying that it was cold and there was much
snow. But under this heading I wish to argue that there was
no difference in the character of the climate between that and
now—merely a lowered annual temperature and _ probable
increased snowfall. The present climate of the Sierra Costa
Mountains partakes of the general equability of the Pacific Coast
region, but in addition possesses a typical alpine character. A
strong contrast between the heat of night and day, and between
that of light and shadow, is a characteristic of high altitudes where
the atmosphere is clear and light, and radiation rapid. One
may suffer from the heat in toiling up a sunny slope, while the
air in the shadow of a peak may seem almost freezing cold.
This is the condition of today at the higher levels of the Sierra
Costa Mountains, and the behavior of the glaciers indicates that
the same obtained in their time. They were unusually sensitive
to sunlight, and shrank into the shadow of the peaks.

Gulches which faced the sun were unglaciated, altho perhaps
surrounded by others in which ice accumulated to a depth of
over 1000 feet. In fact, shadow was as much one of the neces-
sary conditions of glaciation as cold and snow fall. This shows
that the climate possessed the same alpine character as today.
I am strongly impressed that the evidence indicates an altitude
for these mountains during the Wisconsin epoch, at least as
great as the present.

A POSSIBLE CAUSE OF THE GLACIAL PERIOD IN THE SIERRA COSTA
MOUNTAINS

I am not prepared to argue conclusively as to why these
glaciers formed in the elevated valleys of the northwestern Cali-
fornia mountains; but I wish to present, in closing this paper,
what I conceive to be a possible explanation of their existence,
an hypothesis sufficient to account for all their phenomena.

The valleys where the ice accumulated are all above 6000
feet of altitude, and the sites of the main mévés approximate a
general elevation of 6500 feet above the sea. Even today the

GLACIERS OF THE SIERRA COSTA MOUNTAINS 55

climatic conditions at this altitude are not far removed from
those favoring glaciation. The winter snow fall on the mountains
is heavy, they being near the coast. On the higher peaks, light
flurries of snow are often seen in July, and by the end of October,
the winter’s snow has set in in earnest. Storm after storm ensues
thruout the winter and well on into the spring. ley yore a
it is no uncommon thing for the higher mountains to be
sheeted under eight, ten, fifteen, or in places as much as twenty
feet in depth of well-packed snow. This melts away slowly. By
June, most of it is gone; by July, nearly all; but some remains
all the year on the northern slopes of Mt. Thompson and Granite
Peak and in sheltered ravines of Mt. Courtney. This perennial
snow lies at altitudes of about 8000 feet.

Now, in my opinion, a general uplift of the entire region to
the extent of 3000 feet would be a sufficient cause for the dupli-
cation of the ancient glaciers and a restoration of the whole
mountain range to its condition in the Wisconsin epoch. That
would carry the summits of all the peaks above 10,000 feet,
elevate the main ones, such as Granite Peak and Mt. Courtney,
LOM, OOOManGd) 11,500) feet and: Mit. Thompson would tower to
the altitude of 12,345 feet, comparable with Mt. Shasta. The
heads of the glaciated valleys would be elevated to 9500 feet.
If perennial snow lies today in small ravines at 8000 feet, how
readily must it have accumulated in deep valleys over 1500 feet
higher and in the shadow of peaks towering to 11,000 and
12,000 feet. Considerable bodies of snow lie all the year at no
greater altitude on the sunny side of Mt. Shasta, and one may
see snow on any summer day by glancing at Lassen Peak whose
altitude does not much exceed 10,000 feet. Both these moun-
tains are far from the coast, in a comparatively dry belt.

From their nearness to the Pacific Ocean, the elevated Sierra
Costa Mountains must have received a heavier snow fall at a given
altitude than Mt. Shasta. Also, being a group of mountains
(acting like an elevated plateau) instead of a single isolated
peak must have favored a lowering of the temperature and
increased precipitation. Even without an added snow fall, a

56 OS GAVEL Pa Sea

simple elevation would not fall far short of reproducing the
glaciers. But as the result of the uplift, it is safe to count on a
greatly increased precipitation. It appears to me evident that
the present conservative estimated average for the higher regions
of ten feet annually might be doubled. Of this amount one
half, or ten feet in thickness, might melt from the surface of the
névés during each summer (the sun finds difficulty in removing
that amount even at present altitudes). The remaining ten feet
might compact into one foot of ice. Were there no loss by out-
flow and melting at the end of the glacier, the accumulation of
one foot of ice annually would reproduce the large Salmon
River glacier in 1500 years.

But a large part of the ice moved outward beyond the zone
-of accumulation and was lost by melting. This loss was partly
compensated for by heavy snow-slides from the surrounding
precipitous peaks; yet, with the greatest latitude, we must allow
two or even three times as great a period as that first men-
tioned for the accumulation of the glacier, and the attainment
of its maximum extent. I consider 5000 years as a fair esti-
mate, and one which is not too strongly open to criticism. By
a lowering of the altitude to the present and consequent increased
mildness of the climate (in other words, a restoration of present
climatic conditions), probably about half that time or 2500 years
would be sufficient to cause the disappearance of the glaciers,
and give time for the repeated slight readvances which marked
their recession.

The preceding is intended merely as a suggestion, a hypoth-
esis worthy of serious consideration. The demonstration of
its reliability will depend upon external evidence of the sup-
posed temporary uplift of these mountains. This can only be
secured by careful geological work between this range and the
sea, which has not yet been done.

The importance to glacialists in general of studies on the
localized Quaternary glaciers of limited mountain districts lies
not so much in the contrast between their alpine features and
the continental features of the great North American and

GLACIERS OF THE SIERRA COSTA MOUNTAINS 57

European ice sheets, as in the bearing which they may have on
the fascinating and yet unsettled question of the ‘‘Cause of the
Glacial Period.” After trying unsuccessfully to solve the prob-
lem through a study of the varied series of drift sheets in the
Mississippi basin, I have concluded that we will do well to take
into account such evidence as may be gathered in alpine regions
of glaciation—outlines of the main sheets, we may say—for
here the problem of determining climatic changes is less obscure.
The suspicion is growing in my mind that the ‘Glacial Period”
in geology, as a glacial or relatively cold epoch of time, was of
world wide extent in its effects, and the absolute determination
of the cause of the past accumulation of glacial ice in one sec-
tion will be the key to the solution of the problem of all terres-
trial glaciations.

Oscar H. HERSHEY.
November 18, 1899.

BON AIMS IMEI WO) IASI Wels, INISISUILAIR Ie PO WSUS SIS
BY DHE RELATIONS OR MASSES PAN De ViO©MEE INGA

In a paper entitled “A Group of Hypotheses Bearing on
Climatic Changes,’ read before the Geological Section of the
British Association for the Advancement of Science at the
Toronto meeting in 1897, 1 assigned reasons for doubting the
Laplacian hypothesis of the origin of the solar system, based on
deductions from the kinetic theory of gases. These doubts had
arisen in the course of certain atmospheric studies springing
from the problem of ancient glaciation. The complete demon-
stration by the geologists of the far Orient that extensive ice
sheets developed on the borders of the torrid zone in India,
Australia and South Africa during a late stage of the Paleozoic
era had made it imperative to seriously reconsider inherited
views relative to the nature of the earth’s early atmospheres,
and this in turn forced an inquiry into the current postulate of a
primitive, vast, gaseous envelope exceptionally rich in carbon
dioxide; for the special heat-absorbing qualities of this constitu-
ent render it doubtful whether its presence in large amount is
compatible with glaciation. The inquiry led to the application
of such tests as could be derived from the doctrine of molecular
velocities. As the result of such application it appeared quite
impossible that a hot gaseous ring formed of the matter of the
earth and moon, and having the dimensions postulated by the
Laplacian hypothesis, could retain its water vapor and atmos-
pheric gases, for its gravitative control over these was found
to be far below what was necessary to overbalance their molecu-
lar velocities. It appeared very doubtful whether any of the
matter of the ring, even that having the lowest molecular veloci-
ties, could be retained at the postulated temperatures and tenu-
ity. The test seemed altogether decisive against the Laplacian
hypothesis if the kinetic theory be true and the computed

tPublished in full with supplementary tables in the Jour. GEOL., Oct—Noy.,
1897, pp. 652-683.
58

TE SMNOM Mi INE ROAR LLY PO DHE SLS 59

molecular velocities essentially correct. However, the kinetic
theory is perhaps not yet beyond its trial stages, though it is
probable that the essential postulates involved in the doctrine
of molecular velocities are true whatever the precise interpreta-
tion of the facts may be. There is an accord between the
doctrine and the facts in the solar system which strengthens this
conviction. There is an absence of atmosphere from all satel-
lites and asteroids, so far as can be determined. The planet
Mercury has little or no atmosphere. The small planet Mars
has but a thin atmosphere. The Earth and Venus have consid-
erable gaseous envelopes, while Jupiter and Saturn appear to
have vast and deep atmospheres; in short, there is a general
correspondence between the mass of the atmosphere and the
gravitative competency of the body. In still further evidence is
the essential absence of the lightest gases, hydrogen and helium,
from the earth’s atmosphere.*. The tormer, to be sure, is chem-
ically active, but the latter is very inert.

Notwithstanding the apparent strength of the molecular
argument, other tests, based on quite independent grounds, are
desirable. The more is this true since a modification of the form
of the Laplacian hypothesis in which a lower temperature and a
meteoroidal state are postulated deprives the molecular argu-
ment of much of its bearing. It is true that this change in the
hypothesis when carried out consistently in its full application
permits, if, indeed, it does not require, a revision of some of the
fundamental doctrines of current geology, such as the former
molten state of the earth and the long train of doctrines that
hang upon this. So profound is the influence of this primal con-
ception of a molten earth upon the dynamical conceptions and
historical interpretations of the earth’s evolution that every
source of light bearing upon it has an importance we can
scarcely realize at present.

* “On the Cause of the Absence of Hydrogen from the Earth’s Atmosphere and
of Air and Water from the Moon,” by Dr. Johnstone Stoney, Royal Dublin Society,
1892. Also “Of Atmospheres upon Planets and Satellites,” by the same, Trans. Roy.
Dublin Society, Vol. VI, Part 13, Oct. 25, 1897; also ‘A Group of Hypotheses Bear-
ing on Climatic Changes,” by T.C. Chamberlin, Jour. GEOL., Vol. V, No.7, Oct.-
Nov., 1897.

60 Ms (En Glas d DIsILION

The laws of dynamics afford a firm ground of inquiry so far
as they can be brought into service. As applied to mass and
momentum they are rigorous, and so far as they can be covered
by satisfactory computation they are decisive. The purpose of
the present paper is to set forth the results of an attempt to
apply these laws to the nebular hypothesis in certain ways that
are more or less unfamiliar. These results are the outcome of
a joint inquiry by Dr. F. R. Moulton and myself. They are a
part of the results of a more or less continuous study on related
themes lying on the border-land of geology and astronomy, run-
ning through the past three years. Our relations have been so
intimate and our exchanges of ideas so free and so frequent that
it is impossible to apportion the responsibility for the various
-methods adopted and the modes of carrying them out. The
higher mathematical work is, however, to be credited to Dr..
Moulton. It has perhaps been my function in the main to for-
mulate problems and suggest general modes of attack, and Dr.
Moulton’s to devise methods of analysis and bring to bear the
mathematical principles of dynamics, but this has not been uni-
formly so. Quite often we have proceeded by successive alter-
nate steps in which each was the parent of its successor. In a
paper in the Astrophysical Journal published essentially concur-
rently with this, by mutual understanding, Dr. Moulton dis-
cusses not only the bearings of the ratios of masses and momenta
treated in this paper, but several other modes of testing the
nebular hypothesis, some small part of which have been touched
upon in my previous papers and some of which will be discussed
in these pages later. The mathematical treatment of the present
theme will be found in Dr. Moulton’s paper.

For convenience and definiteness, the treatment here will be
based on the Laplacian phase of the nebular hypothesis, but the
conclusions will be found applicable, in all essential respects, to
such meteoroidal modifications of the hypothesis as postulate a
spheroidal form controlled by the laws of hydrodynamic equilib-
rium.

ESE NOLO TLE NEO A fe Lf VPO DALE STIS 61

1. Comparison of the moment of momentum of the nebular system
with the moment of momentum of the present system.—\t is a firmly
established law of mechanics that any system of particles of any
kind whatever rotating about an axis retains a constant moment
of momentum whatever changes of form or arrangement the
matter may undergo by virtue of its own interaction. To make
this law rigorously applicable to the solar system evolving along
Laplacian lines, the influence of external and of incoming bodies
must be excluded. Foreign meteoroidal matter has doubtless
been added constantly to the system during its evolution, but
the amount of this is assumed to be negligible; and if it were not,
the law of probabilities would render its effect upon the rotation
of the system an essentially balanced one, and hence immate-
rial. The following argument proceeds upon the Laplacian
assumption that the system evolved through the operation of its
own inherent dynamics. On this assumption the sum total of
rotational and revolutionary momentum must have been the
same at all stages of the system’s evolution.

The following table gives the masses. and the present moments
of momenta of the several members of the solar system and of the
whole system. They are taken from Darwin’s paper, ‘‘On the
Tidal Friction of a Planet attended by several Satellites and on
the Evolution of the Solar System,’ * and are employed in the
subsequent computations. The masses assigned the planets
embrace those of the attendant satellites.

Body Masses (Earth r) Moments of Momenta (Darwin)

; Laplace’s density law (Min.
oun ‘ SED ys 20008 ae ) euaceerane ee ees
Mercury - .06484 .00079
Venus - -78829 .01309
Earth - - 1.00000 ,01720
Mars - .10199 .00253
Jupiter - 301.09710 1 3.46900
Saturn - g0.10480 5.45600
Uranus - 14.34140 1.32300
Neptune - 16.01580 1.80600 »

Solar System 315,934.51422 eee ae

t Phil. Trans. Roy. Soc., Part II, 1881, pp. 516, 517.

62 Ms (Op (CLEAN EMPIRIC ION,

The distribution of density in the sun is unknown. If it
follows Laplace’s law the rotatory momentum is .444. If it be
regarded as homogeneous, the rotatory momentum is .679. This
latter is certainly too large, and the former number is probably
much nearer the truth, but the larger number is used in the
greater part of the computations because it 1s more favorable to
the Laplacian hypothesis.

To obtain the rotatory momentum of the ancestral nebula it is
necessary to consider its form, extent, and the variation of its
internal density. By hypothesis the form was an oblate sphe-
roid, but the exact degree of polar flattening is unassigned.
Simple inspection, as well as mathematical analysis, shows that
a given mass of matter rotating as a sphere will have a less
-moment of momentum than when it takes the form of an oblate
spheroid, the time of rotation and other factors being equal. If
a yielding sphere be rotated it takes the spheroidal shape because
that is the form of equilibrium for the added rotational momen-
tum), and is) an expression: of such, additions Silom onesie
Laplacian hypothesis the benefit of every doubt, the moment of
momentum of the nebula is computed on the basis of a sphere.
So also to favor the hypothesis, the nebula is made to reach
merely ¢o the orbit of the derived planet, not to extend beyond
it as is usually and necessarily assumed. In computing the rota-
tory momentum of the whole nebular mass just before Neptune
was separated, it is assumed that it reached only to Neptune’s
orbit, whereas the nebular border must prey have extended
some 500 million miles beyond.

As this question of the distribution of the matter from which
the planets were formed under the Laplacian hypothesis has
other applications, it may be remarked here that in the forma-
tion of a planet from a ring of dispersed matter the planet must
assume such a point within the ring as to preserve the moment
of momentum of the mass. In asymmetrical ring this point is
somewhere near the center of the cross section. Though sub-
ject to some qualifications from the greater circumference of
the outer part and the possibly greater density of the inner part

TEST OF THE NEBULAR HYPOTHESIS 63

and other contingencies, it will be sufficiently accurate for the
purposes of this discussion to assume that the planets were
formed in the centers of their respective rings, and that the
Space appropriate to each planet reached half way to the
neighboring planets.

The more important consideration, however, in determining
the rotatory momentum of the ancestral nebula is the distribution
of its internal density. Our method has been to compute this
on the basis of the recognized laws, using in particular the
formula of Lane, and to compare results with the previous deter-
minations of mathematicians and physicists."

The distribution of density in such a nebulous sphere has
been the subject of investigation by Lane, Ritter, G. W. Hill,
George Darwin, Lord Kelvin, and others.2, The results reached
by all are in substantial agreement, though somewhat different
analytical methods were followed. In obtaining the final numer-
ical results used in this paper, the distribution of density found
by Darwin was adopted. The method of computation is given
in Dr. Moulton’s paper in the Astrophysical Journal.

When the solar nebula extended to the orbit of Neptune and
embraced the matter of the whole system and had a rotation

*The laborious work of making the computation was undertaken by Mr. C. F.
Tolman, Jr., under the direction of Dr. Moulton, and preliminary results were
obtained by him, but before these had been sufficiently verified he was called to a
position whose immediate requirements prevented the completion of the desired veri-
fication. For this reason, and for the obvious advantage of resting the present argu-
ment as far as possible on the computations of an acknowledged authority, results
reached by Darwin, which are applicable to a gaseous or meteoroidal nebula in con-
vective equilibrium, have been adopted.

*LANE: On the Theoretical Temperature of the Sun under the Hypothesis of a
Gaseous Mass Maintaining its Volume by its Internal Heat, and Depending on the
Laws of Gases as Known to Terrestrial Experiments, Am. Jour. Sci., Vol. XLIX, pp.
56-74, 1870.

RITTER: Untersuchen iiber die Hohe der Atmosphare und die Constitution
gasformiges Weltkoper, Wiedemann’s Annalen (New Series), Vol. XVI, 1882, p-. 166.

G. W. HiLi: Annals of Mathematics, Vol. IV, 1888.

DARWIN: On the Mechanical Condition of a Swarm of Meteorites, and on the
Theories of Cosmogony, Trans. Phil. Soc., 1888.

KELVIN: On the Origin and Total Amount of the Sun’s Heat, Popular Lectures
and Addresses, 1891. Constitution of Matter, pp. 370-429.

64 1 (O- (CLEIANI EV ELIE JUN

equal to the angular velocity of Neptune, its computed moment
of momentum was 4848.055, while the present moment of
momentum is 22.7666. The unit is an arbitrary one arising from
the selection of convenient initial units. In this paper, Moul-
ton’s unit is converted into Darwin’s unit, for convenience of
comparison. It appears, therefore, that notwithstanding the
concessions to the Laplacian hypothesis by which the present
moment of momentum was made too large, and the nebular
moment of momentum too small, the latter is still 213 times
larger than the former. The dynamical law that demands con-
stancy of moment of momentum is not even remotely fulfilled.
A more rigorous computation, following the probabilities of the
case without regard to its bearings on the Laplacian hypoth-
esis, would increase the discrepancy.

Individual discrepancies.—N ot only does the law fail of realiza-
tion when the present system taken as a whole is compared with
the ancestral nebula, but also in a comparison between the
successive nebular stages and the corresponding parts of the
present system. For example, the computed rotatory momentum
when the nebula extended to Jupiter’s orbit, and included the
Jovian mass, was 1996.420, while the moment of momentum of
the present system, minus the moment of momentum of Neptune,
Uranus, and Saturn, is 14.1816. The discrepancy here is more
thansi4@ toy 1.

When the nebula extended to the earth’s orbit, and included
the terrestial mass, its moment of momentum was 857.330.
The moment of momentum of the Earth, Venus, Mercury, and
the sun, by hypothesis formed from this nebula, is only .71008.
In this case the excessive estimate of the sun’s moment of
momentum, due to the assumption of homogeneity, introduces a
disproportionately large error, and yet the discrepancy is 1208 to
1. Computing the sun’s moment of momentum on the basis of
Laplace’s law of destiny, the discrepancy is 1801 to I.

When the nebula extended to Mercury’s orbit, and included
this planet’s mass, its moment of momentum was 512.290, while
the moment of momentum of Mercury and the sun (excessively

TEST OF THE NEBULAR HYPOTHESIS 65

estimated) is 0.67979, making the discrepancy 754 to 1. On the
more probable basis of Laplacian solar density the difference is
W277 tO. Ih.

From these data it appears that there is not only a funda-
mental and pervasive discrepancy between the computed nebular
momentum and the actual present momentum, but there is also

‘a strange irregularity in the discrepancies themselves. A funda-
mental error in the analytical work, or in the assumptions on which
it is based, should give a systematic error, or at least a graded
series of errors. But the discrepancy shown is not systematic
or even graded. Not only are the discrepancies enormously
large in themselves, but their irregularities are also large. This
will appear better by bringing them together into a table.

Nebular M. of M. Present M. of M. Ratios,
Neptunian stage, 4848.055.............. 22.70061 213 tol
Jovian LSE LO OOMAZ ON Mba mcretencaie 14.18161 141 to I
Terrestial 4 SIRES 8 Om tueien seatanel aetna 0.71008 1208 to I
Mercurial ss EAT DE OO cices cue tere taal « 0.67979 754 to I

2. Can these discrepancies be due to a radical error in the law
of density ?—It is certain that Boyle’s law is not rigorously appli-
cable to gases under all conditions, and it is pertinent to inquire
whether any deviation from it can account for the discrepancies
which the foregoing computations reveal. The researches of
Amagat* and others have shown the nature of the deviations
within the limits of experimental tests and Van der Waals’ law
furnishes a basis for the theoretical extension of these results to
other conditions.

Near the temperatures of liquefaction the density increases
faster than the law requires. Obviously the exterior of the
nebula would be effected by lower temperature than its interior
and would be most influenced by this variation so far as depend-
ent on low temperatures. As the peripheral portion carries the
largest part of the rotatory momentum any increased density there
through failure of Boyle’s law would increase the discrepancy.

*WULLNER: Experimental Physik. Tables. Vol. I, p. 542.

66 IMS (On (CLELAWEDE/SILIONY.

In the interior of the nebula the temperatures were probably
far above the critical temperatures of all known substances, and
this renders it improbable that central liquefaction prevailed
during the nebular stages; indeed the very dispersion of the
matter into so vast a volume as the Laplacian hypothesis postu-
lates may perhaps be taken as an implicit assertion of the domi-
nance of the gaseous laws throughout the mass. This is certainly’
the view of its ablest exponents. Lord Kelvin speaking of a
globular gaseous nebula (selected to represent the primitive neb-
ula), having the mass of the solar system and a radius forty
times the radius of the earth’s orbit, says: ‘The density in its
central regions, sensibly uniform throughout several million kilom-
eters, is one twenty-thousand millionth of that of water; or
one twenty-five millionth of that of air.”* Similar determinations
may be found in the more elaborate computations of Darwin for
varying dimensions of the nebula.* We are therefore apparently
not dealing with densities, even in the central parts, greater than
those covered by experimental evidence.

Besides, the present distribution of matter in the solar system
offers an independent argument against any great central lique-
faction, until after the earth was separated at least, for, by hypoth-
esis, the earth was formed from the extreme equatorial periphery
of the nebula, but the larger part of its material is of the most
refractory kinds known and would pass into the liquid and solid
states early in the history of condensation. There seems little
ground therefore for assuming any effective condensation of the
central matter of the nebula during at least the early stages of
planetary evolution.

On the other hand, experimental evidence and theoretical
deductions alike indicate that under very high pressures, where
the temperature is also above the critical point, the density fails
to increase as fast as the pressure. As these are the assigned
conditions of the central part of the nebula, any failure of the
law in this direction would increase the discrepancy.

‘Popular Lectures and Addresses, I. Constitution of Matter, p. 419.
2(Qn the Mechanical Conditions of Swarms of Meteorites, and on Theories of
Cosmogony, Phil. Trans. Roy. Soc., 1888.

LE SUVOL. Li rMNEO BOE ARYL VPO TEE STS: 67

It does not appear therefore that there are good grounds for
assuming a failure of the recognized law of density in such a
direction as to relieve the great discrepancy shown by the com-
putations. In any case there is the gravest reason to doubt
whether it could reach a value represented by a multiplier
ranging from 140 to 1200, not to say 1800.

But even if an arbitrary attempt were made to reduce the
computed moments of momenta to consistency with those of the
existing system, it is not apparent how it could be attended with
success and preserve self consistency. The discrepancies are :

For the Neptunian nebula - - - = BYU WO I
For the Jovian se - - - - I41 to 1
Hovthemlerrestialy <6 — - - - = 1208 to I
(or on the more probable basis) - - 1801 to I
For the Mercurial nebula - - - - 754 to!
(or on the more probable basis) — - - 1127 to I

Now any deviation from the recognized law must be supposed
to be consistent for analogous conditions. Iftherefore we assume
such a modification as to bring the moment of momentum of the
Neptunian nebula into equality with the present moment of
momentum, we must assume that a similar modification held
good for all the subsequent stages, either in the same proportion
or in some systematically increasing or decreasing proportion.
But the ratios succeed each other in a very arbitrary way, and
the Neptunian divisor will not bring the others into accord, nor
will any obvious series of divisors built systematically upon it.
Were the computation extended to the other nebule, additional
irreducible irregularities would doubtless appear.

3. The ratio of masses to momenta.—In the symmetrical
evolution of a spheroidal nebula by secular cooling, as postu-
lated in the Laplacian hypothesis, it is reasonable, if not neces-
sary, to suppose there would be some systematic and rational
relationship between the masses separated from time to time and
the moments of momenta of these masses, for the separation was
due to a common progressive cause, the acceleration of rotation.
The hypothesis may therefore be tested along these lines. In

68 Li Con CLANS ETN

the test here applied the question of nebular density does not
enter, and certain assumptions that might be made to meet the
previous discrepancies are here checked.

Just previous to the hypothetical separation of the Jovian
ring from the solar nebula the moment of momentum of the
latter, reckoned from the present momenta of its derivatives, was
14.1816, if the sun be regarded as homogeneous, or 13.947, if
the sun’s density followed Laplace’s law which is probably much
nearer the truth. Of this, Jupiter now has 13.469. Neglecting
for the present subsequent transfers of momentum, it follows that
when the Jovian ring separated it carried away 13.469 / 14.182 or
about 95 per cent. (94.97 per cent.) of the total moment of momen-
tum of the nebula (or 96.57 per cent. on the more probable basis).
Now the mass of Jupiter’s ring was 1 / 1049 of the parent nebula, or
less than one tenth of 1 percent. It thus appears that the unquali-
fied Laplacian hypothesis involves the implicit assertion that in
the formation of the Jovian ring less than one thousandth of the
mass carried away 95 per cent. of the moment of momentum. Is
this possible in a spheroid of gaseous or quasi-gaseous material
in convective equilibrium? One nineteen-thousandth more of
the mass thrown off with an equal proportion of rotational
momentum would have exhausted the supply. Apparently the
minor planets had a narrow escape from not being at all.

Similar but not uniform disparities appear in a comparison
of the masses and momenta of the other planetary rings with
their parent nebule. In such a comparison also the great dis-
parities in the planetary masses become conspicuous.

The mass of the Neptunian ring was about five thousandths
of I per cent. of its nebula and by hypothesis it carried away
about 8 per cent. of the moment of momentum of the nebula.

The mass of the Uranian ring was four and a half thousandths
Oi Woe CeMu, Ou tes nebula. It hypothetically carried away 6
per cent. of the nebular moment of momentum.

The mass of the Saturnian ring was less than a third of a
hundredth of 1 per cent. of its nebula and yet it carried away 27
per cent. of the nebular moment of momentum.

LESINOF THE NEBULAR HYPOTHESLS (ole)

The mass of the Martian ring was three hundred-thousandths
of I per cent. of its nebula, and yet it took away 0.35 per cent.
of the moment of momentum of the nebula.

The mass of the Terrestrial ring was less than a third of a
thousandth of 1 per cent. of its nebula, and it carried away 2.4
per cent. of the nebular moment of momentum.

The mass of Venus’ ring was about one fourth ofa thousandth
of I per cent. of its nebula, and it carried off 1.89 per cent. of
the nebular moment of momentum.

The mass of the Mercurial ring was only about one fifth of a
ten-thousandth of 1 per cent. of its nebula, and it hypothetically
carried off 0.12 per cent. of the nebular moment of momentum.

Not only are these ratios very extraordinary in themselves,
but their relations to each other seem scarcely less remarkable.
This will appear more apparent when they are gathered into a
table and referred to a common unit. This unit is one one-
hundred-thousandth of I percent of the individual nebular
mass. It will be seen that on this proportional basis, the moments
of momenta range through a gamut of more than ten points,
the proportion of Mars being more than ten times that of its
neighbor Jupiter.

: Percents of M of
Ring Perea | OEBCOTEE, | of-encorsofnebu:
lar mass.
INGOULIMIAM 5 cade vostlooc's aceds 0.00507 F O38} .0156
iI iel ve poe edEo BORO COO omemO 0.00454 6.31 .0139
SatuEM lamp. sets cceteitersic sel ois ee 0.02852 27.78 .0098
LIGNIN AiaS Aiea eens rere teen ares 0.09530 94.97 .00996
Miler bi ames coe tue Shes elke alesitansiaus sists 0 .0000323 0.36 . 1099
PIRETeS ticlalllt Shosetsgere si cueuel cveietes exe ats 0 .0003160 2.42 .0766
VGH So Spe ca Omen ee creiareseae 0.0002495 1.89 .0755
Wren cumialleyiy. con cust. satteeniestrec, cones 0 .0000205 0.12 .0566

There seems to be no systematic variation in these. It is
furthermore remarkable that, high as is the ratio of Jupiter’s
moment of momentum to the parent nebula, it is proportionately
surpassed in most other cases.

4. Can these high ratios of the moments of momenta of the planets
to the residual nebule be attributed to transfer of moment of momentum

70 1s (On, Cle EISIL ION

from the sun by tidal friction ?——-Darwin has made familiar the
principle of the transfer of the moment of momentum of a rotat-
ing body to its satellite by his classic investigation of the
evolution of the earth-moon system. Applying this principle
to the solar system, is it possible to explain the low rotatory
momentum of the sun and the high moments of momenta of
the planets by a transfer of momentum from the former to the
latter ?

The most obvious and tangible effect of solar tidal friction
on the planets is to destroy their rotations. The patent fact
that most of them still retain high speeds of rotation is a
physical expression of the limitations of past tidal action.

Darwin has computed the rotational momenta of all the
planets that afford the requisite data and also the revolutionary
momenta of their satellites. Making a generous allowance for
the unknown and uncertain factors and counting in unnecessarily
the orbital momenta of the satellites, the whole internal
momentum of the planetary systems falls short of a thousandth
part of the sun’s rotational momentum computed on the minimum
basis. This means that to have reduced the sun’s rotational
momentum from twice the present amount to the existing status,
and to have transferred this to the planets, more than a thousand
times the total rotatory momentum of all the planets must have
been destroyed. But this would be only a slight step toward
the adjustment contemplated.

To realize what might be necessary, if the foregoing nebular
computations are well founded, let the matter of the solar system
be converted into a gaseous nebula in hydrodynamic equilibrium
extending beyond the orbit of Neptune; let this nebula be
given the moment of momentum of the present solar system,
and then let it contract by cooling, with the development of
accelerated rotation, as postulated in the Laplacian hypothesis.
An inspection of the foregoing data will show that the centrif-
ugal force would not become equal to the centripetal force until
the nebula had shrunk far within the orbit of Mercury. The

*On the Tidal Friction, etc., pp. 519-523.

THSL OF THE NEBULAR HYVPOTHE STS gat

tidal problem then becomes the dispersal of the planets from
this central position to their present places.

Concerning the competency of the solar tides to alter the
orbits of the planets (and hence their moments of momenta),
Darwin says:* ‘“‘It may be shown that the reaction of the tides
raised in the sun by the planets must have had a very small
influence in changing the dimensions of the planetary orbits
around the sun. From a consideration of numerical data with
regard to the solar system and the planetary subsystems, it
appears improbable that the planetary orbits have been sensi-
bly enlarged by tidal friction since the origin of the several
planets.” Again, he says:* “If the whole of the momentum
of Jupiter and his satellites were destroyed by solar tidal fric-
tion, the mean distance of Jupiter from the sun would only be
increased by one twenty-five hundredth part. The effect of the
destruction of the internal momentum of any of the other planets
would be very much less.” sAnd again:3 ‘‘The present investi-
gation shows, in confirmation of preceding ones, that at this
origin of the moon the earth had a period of revolution about
the sun shorter than at the present by perhaps only a minute
or two, and it also shows that since the terrestrial planet itself
first had a separate existence the length of the year can have
increased but very little, almost certainly by not so much as an
hour, and probably by not more than five minutes.”

Aside from the quantitative difficulties there are formidable
qualitative ones growing out of the proportional distances of the
planets and the enormous lapses of time involved in a tidal
retrogression of the planets through the postulated distances.

Conclusions —The general result of the inquiry is to show, if
we have not somewhere fallen into error, various relationships
of mass and momentum which are seemingly altogether incom-
patible with an evolution of the solar system from a gaseous
spheroid controlled by the laws of hydrodynamic equilibrium

‘Encyclopedia Brittanica, Article “ Tides,” p. 380.

2On the Tidal Friction, etc., p. 524.

3 Loc. cit., p. 533.

72 TT. C. CHAMBERLIN

and developing by secular cooling. The argument is equally
cogent against an evolution from a meteoroidal spheroid con-
trolled by the laws of convective equilibrium, such, for example,
as that made the subject of investigation by Darwin in his
memoir: ‘On the Mechanical Conditions of a Swarm of
Meteorites and on Theories of Cosmogony.”’

The results point to an unsymmetrical distribution of matter
and of momentum. It should go without saying that we assume
a nebular origin in the broad sense of the term, but the inquiry
seems to show that the original form of the nebula and the
mode of its development are to be sought on new lines. The
foregoing data seem to constitute criteria of a rather rigorous
nature to which a working hypothesis must conform. They are
thereby aids in the construction of a tenable hypothesis. They
seem to require the assignment of some mode of origin by
which the peripheral portion of the system acquired all but a
trivial part of the moment of momentum, while it possessed but
a trivial part of the mass. The first suggestion of these con-
clusions was the possible formation of the system by the collision
of a small nebula upon the outer portion of a large one, the
smaller one having necessarily a high ratio of momentum to
mass, while the larger one may have had little or no rotatory
momentum, or even an adverse rotation. The low degrees of
ellipticity of the present orbits seem to present grave difficulties
in the framing of a consistent hypothesis of origin along this
line, but these may not prove insuperable.

The results also naturally turn thought anew toward axwiing
nebula for an exemplification of the evolution of the solar system.
It is not a little significant that of the thousands of nebula now
known no one, I believe, closely represents the annular process ;
certainly none represents the secondary annulation coincident
with the primary. To bring the current hypothesis into con-
sistency with observed nebular states, it seems necessary to
assign it to so late a stage of concentration and to such small
dimensions as to be beyond observation——at most, a hypothetical
resort.

TEST OF THE NEBULAR HYPOTHESIS 73

Following a purely naturalistic and inductive method, it
would seem that the spiral nebula, whose abundance is attested
by the recent notable success of Professor Keeler in photograph-
ing numerous small ones, offer the greatest inherent presump-
tion of being the ancestral form. While present knowledge of
their dynamics is almost inappreciable, the suggestions of their
forms and the distribution of their matter do not seem neces-
sarily incompatible with the criteria deduced in this inquiry.

Both these suggestions are obviously very immature, and
have their sole justification in a natural reluctance to offer
destructive results only —a reluctance intensified by an acute
consciousness that the hypothesis against which they are directed
is perhaps the most beautiful and fascinating ever offered to the
‘scientific public.

T. C. CHAMBERLIN.

EDI PORIvs

For more than thirty years Mr. W. F. E. Gurley, of Danville,
Illinois, formerly the official geologist of this state, has been one
of the most systematic collectors of Paleozoic fossils in the Mis-
sissippi valley. Not only has he gathered together what is prob-
ably the best existing collection of Paleozoic fossils of the
interior states, but he has secured a large amount of valuable
material from other portions of this country and from Europe.
The collection has furnished much material for study to such
paleontologists as ‘EA. White, #. 1) Cope, Seni Scudders| as:
Newberry, Leo Lesquereaux, and Charles Wachsmuth, and many
types of the species described by these men are included in it.
More recently Mr. Gurley himself, associated with the late S. A.
Miller, of Cincinnati, has described many new species from the
collection. Aside from these types Mr. Gurley has been fortu-
nate in securing many other types of species described by Owen
and Shumard, Hall, Wetherby, and Miller.

In addition to the types in the collection, which are about
600 in number, some of its most noticeable features are the fol-
lowing: an exceptional series of Devonian fossils from the
falls of the Ohio, including crinoids, corals, brachiopods, and
trilobites; a fine series of Kinderhook crinoids from Le Grand,
Iowa; an admirable series of Coal Measure crinoids from Kan-
sas City, Missouri; a large collection of fish remains from the
limestones of the Mississippi valley ; an almost exclusive collec-
tion of the vertebrate remains from the Permian bone bed near
Danville, Illinois, including all the types of the species from this
locality described by Professor E. D. Cope; and a fine series of
blastoids and cystoids. Among the foreign material a choice
series of Solenhofen slate fossils and an excellent series of Car-
boniferous crinoids from Moscow, are worthy of special mention.
These features serve to show something of the contents of the

74

EDITORIAL 76

collection, but they constitute only a small portion of the whole.
The entire collection is estimated to contain 15,000 species and
several hundred thousand specimens-

Through the generosity of Mr. Gurley himself, this collection
has recently become the property of the University of Chicago.
It will be installed in Walker Museum as rapidly as possible and
will constitute the nucleus of still further growth. It will be the
policy of the University to make this collection, and the future
additions to it, not merely an exhibition of rare and choice
fossils, but a basis of research which will be open to competent
students under approved conditions. It will, beyond question,
prove to be eminently serviceable in promoting appropriate lines
of investigation and will thereby constitute a notable contribu-
tion to the progress of historical geology.

STUART WELLER.

REVIEWS

The Diuturnal Theory of the Earth; Or, Nature’s System of Construct-
ing a Stratified Physical World. By WiLL1aAM ANDREWS.
Published by Myra Andrews and Ernest G. Stevens. New
York, 1899. 8vo, pp. 551.

The consideration that might naturally be awakened by the evi-
dences of great labor under manifest limitations embodied in this
posthumous book is well nigh forstalled by the bad taste and absurd
presumption of the preface by Mr. Stevens in which Mr. Andrews is
styled ‘the greatest scientist America has produced” who “left com-
paratively little to be accomplished,” and so forth.

“The Diuturnal Theory of the Earth” consists essentially of the
assumption that “the north terrestrial polar point is taken within 30°
to the south siderial polar point, and returned to within 60° of the
point under the north star, from whence it started,” and that the
essential features of geological history are due to this. This polar
movement is assumed to have taken the form of a spiral migration
involving “‘ six polar transitions’”’ across the eastern and western hem-
ispheres. There is no serious attempt to show that such a movement
was a fact either by inductive evidence or deductive theory. The
author’s method seems to have been the pre-scientific one of develop-
ing a conception essentially ex mzhilo and of interpreting the phe-
nomena by means of it. The book is interesting as an exhibition of
great labor enthusiastically devoted to the broad themes of geology
under limitations that precluded either the mastery of the facts needed
for induction or the dynamic principles necessary for deduction. If
the filial regard which has given it to the world a dozen years after
the author’s death had been content to rest it on the modest basis of
the thoughtful efforts of a studious man working under conditions that
precluded success, it would have been wiser than to put it forth with the
pretentious assumption of having ‘“‘made the patchwork of geology
into a complete science.”

Cane

76

REVIEWS 77

Memours of the Geological Survey of the United Kingdom. The
Silurian Rocks of Britain. Vol. I, Scotland, 1899. By B.
N. Peacu, JoHN Horne, and J. J. H. TEav.

This publication, which comprises the first volume of a proposed
monograph on the Silurian rocks of Great Britain and Ireland, treats
of the Silurian formations of Scotland in a praiseworthy degree of
completeness. It is a work destined to maintain the high standard of
excellence attained by the British Survey Reports.

The opening chapter is devoted to the physical features of the
Silurian region. The region in general comprises the Southern
Uplands which, lying between the Central Lowlands on the north and
the Cheviot Hills and Solway Firth on the south, stretch from the
North Sea to the Irish Channel. The topography of the region varies
from the uniformly smooth or undulating types in the central and
eastern parts to the rugged craggy type of the southwestern part.
The Uplands vary in height from one to two thousand feet. The
northern border is traversed by an extensive fault which lets down the
Devonian and Carboniferous rocks of the north to form the surface of
the Central Lowlands.

The succeeding chapter is devoted to the history of previous
researches among the rocks of this district. These researches cover a
period of more than a century, and have engaged the attention of
many of Britain’s foremost geologists of the past and present. Begin-
ning with Hutton among others are the names of Hall, Fairplay, Nicol,
Harkness, Murchison, Sedgwick, Ramsay, A. Geikie, J. Geikie, and
Lapworth, besides the names of the authors, Peach, Horne, and Teall.
To Lapworth is given the credit of establishing by paleontological and
stratigraphical achievements the true order of succession of the Silurian
strata. His studies of the sequence of the Silurian graptolite faunas
made possible the correction of erroneous estimates of the thickness of
the beds and enabled the structure of the region to be worked out in
the most complicated areas.

The stratigraphy and the tectonic arrangement of the rocks are set
forth in the third chapter of the volume. ‘The Lower Silurian series
is divided into the Arenig, the Llandeilo, and the Carodoc formations.
The Arenig strata consist of cherts, mudstones, shales, and volcanic
tuffs interbedded in places with tuffs, lavas, and agglomerates, asso-
ciated with intrusive masses comprising serpentine, olivine, enstatite

78 REVIEWS

rock, and gabbros. Many of the volcanic eruptions took place under
submarine conditions. ‘There were also periods of quiescence, during
which fine sands and mud containing fossils were deposited.

A subsidence of the sea floor ushered in the next period, the
Llandeilo. The rocks of this formation are radiolarian cherts and
mudstones which were deposited in clearer waters than the rocks of
the Arenig. The rocks of the Carodoc are shales, conglomerates, and
limestones, implying variable conditions of deposition.

The Upper Silurian, it is said, is separated from the Lower Silurian
by both physical and paleontological changes. But there appears to
be no great paleontological break such as characterizes the separation
of the Ordovician from the Silurian on the interior of the American
continent. The transition from the Lower Silurian to the Upper
Silurian types is a gradual one. This province may constitute one of
harbors of refuge spoken of by Professor Chamberlin in his discus-
sion of the source of provincial faunas. It would correspond, then.
on the American continent, to the embayment at the mouth of the St.
Lawrence. The following table will serve to compare the distribution
of the Brachiopods common to the two countries, Scotland and
America :

Scotland America
ae tena eppes n | Ordovician | Silurian

NADA MATCHES oooccpecoue do bec CD00 x x x
LNAI, WNANTTITAVIS. oo concdadoauocdassan x Be aK
(Cyne, @xPOIMRSAI, o odoooocan00soec0 Co00 < x x
Weptaenalrhomboidalisseyr elerteke itera % x xg x
Plectambonites transversalis............ PK x ae x
Blatystrophiaybitonatalyerrncicilericiereu x x x x
Rafesinesquina alternata .............. x a x
BIO MWS DUO 6400 s00G0s000000500000 x x a x
Dalmanellagelesantulaeeiers peecrelere tnt x 58 a Ke
Dalmanella testudinaria................ x x
OU WOCSMATIE o 2556s co0ononooac0GKd0 xe ae x ae
Pentamerusrobloncusie asec eee cece ce ae 5m x
WUncinulussstricklandimeemrencinsrataele cereals XS Xe
SpinifenicniSpusieeeee rie renter x x x
‘Syomaliicie TEGMANENS cseodo mos oceogo ole eons x x
Ratesinesquinasdeltoidearrme icin eet x x Ks
Ratesinesquinmtagimllne xeaeertie niet ot-iponsnrye x a x

Wola! OF GOSCISS 5 so0cndcoavcegesabe 14 II 7 12

REVIEWS 79

This table shows that of the fourteen species occurring in the Lower
Silurian of Scotland but one half that number are represented in the
American Ordovician, the other seven species appearing in the Ameri-
can Silurian. As most of these species’ occur in the last member of
the Lower Silurian, the Carodoc, it is probable that this formation
forms the transition zone between the Ordovician, as we know it, and
the Silurian.

The Upper Silurian series is divided into the Llandovery, the
Tarannon, the Wenlock, the Ludlow, and the Downtonian. ‘These
formations consist of mudstones, limestones, grits, graywackes, and
conglomerates. ‘The Downtonian which hitherto has not been recog-
nized as a part of the Silurian is probably the equivalent of the Water-
lime formation of our own country. It contains a fauna consisting of
Ostracoids, Eurypterids, and fishes similar to the fauna of the Water-
lime formation. This formation immediately underlies the Old Red
Sandstone.

, The economic products of the Silurian formations are lead, iron,
copper, antimony, manganese, zinc, mispickel, silver, and gold, besides
building materials, road-metal, and hone-stones.

Other chapters in the book are devoted to contact-metamorphism,
and to the granites and associated igneous rocks.

W. N. Loca.

Genesis of Worlds. By J. H. Hopart BENNETT. Springfield, IIL:
he WS Nokkers printer, 1O0C; map asA5.

This work does not need serious review from the point of view of
science. It is the product of a mind deeply interested in the prob-
lems of cosmogony and apparently ready to accept the demonstrations
of science, but yet still under the dominance of the traditional
anthrophic mode of thought. It betrays throughout a serious lack of
firm grounding in the elements of the sciences involved in the subjects
under discussion, a grounding absolutely necessary to their successful
treatment. The mode and style of the book may be illustrated by the
following quotation from page 3:

Inquiring minds have a propensity for tracing things to a first cause, and
would ask from whence came the great nebula. It could not have sprung
into existence already formed. It had an origin which is worthy of a most
careful investigation, for it is one of a class that is represented by thousands

80 REVIEWS,

of similar bodies in the heavens. May not a conjecture of its antecedents be
properly presented here? It is that when the great Creator would form a
new system of worlds, having allotted a district of suitable form and dimen-
sions for the purpose, he changes the primordial matter in it from a gaseous
condition, in which it had been under the law of repulsion, into cosmical dust,
by which slight change it became subject to the law of gravitation.

And the following from pages 72 and 73:

Any matter erupted from the sun can return to it again, as it does con-
stantly from its prominences. But there seems to be a repulsion between all
comets and the sun. They are attracted toward it, but never toit. After
one revolution the reason may be given that they have established orbits.
But that reason does not apply to the first approach. Any other bodies gravi-
tating toward the sun from the depths of space would fall directly upon it.
But cometary matter seems to be governed by an unknown law, a law of
gravitation limited. There is attraction at a great distance, but repulsion on
near approach. Is it not evident from the following quotation’? ‘The great
comet of 1843 passed within three or four minutes of the surface of the sun,
and therefore directly through the midst of the corona. At the time of near-
est approach, its velocity was three hundred and fifty miles a second, and it
went with nearly this velocity through at least three hundred thousand miles
of corona, coming out without having suffered any visible damage or retarda-
tion’ (NEwcoms’s Popular Astronomy, p. 251).

Was not that a clear case of mutual shrinkage or gathering of skirts as
two persons would gather their delicate rebes to avoid contact when passing

too near each other ?

Occasionally the style falls off to this:

This hypothesis presents, in a greater degree than any explanation hereto-
fore offered, the elements of possibilities in the tissue of forces and their
observed effects. Indeed those effects demand a reasonable exposition of
producing causes.

The author attempts to solve some of the fundamental problems of
geology by giving enormous magnitude to the rendering and tritura-
ting effects of the descent of the waters of the supposed primitive
vaporous atmosphere upon the assumed hot earth. Respecting this
he says:

The inquiry must arise in every thoughtful mind, to what depth will
the breaking of the rocky crust extend? What can arrest the destructive
action of the water? Will the weight of the débris affect it at the depth
of one mile, or two miles, or three miles? No, nothing can resist the
explosive power of steam. It opens the way and keeps it open for the

REVIEWS rot

downward progress of water. Nothing can arrest the destruction of the
rocky crust so long as there is rock to be broken. The entire solid crust
of the earth must be transformed, must be rent into fragments. The water
reaches the molten mass below and can go no farther.

Again the phenomenal changes and the condition of the earths crust
embarrass our powers of description, and even conception. The water hav-
ing reached the molten mass below the fragmental crust, could go no farther.
It had reduced the temperature of the upper surface more nearly to that of
boiling water, while that of the molten mass below the broken crust was
nearly forty-four hundred degrees higher. The entire mass, thirteen miles
in depth of débris and water, is kept in violent motion by the resistless power
of steam over the entire surface of the globe.

On this ‘‘ true basis,” in negligence of the most obvious limitations
of a well-recognized action, the author builds theories of elevation,
vulcanism and stratification, and assumes that he has solved some of
the great problems of geology.

Those who are not well versed in what is established will read the
book at much risk of mixing needless error with truth, while those who
are so versed will probably find it interesting chiefly as a psychological
study.

The book is pervaded by an ostentatious piety of the type preva-
lent in the last century, which is liable to produce a moral effect quite
opposite tothat intended. True reverence is best displayed by refrain-
ing from presuming to know the mind and purpose of the Infinite and
by scrupulously dissociating one’s imperfect notions from all connec-
tion with Omniscience. ECuC

Text-Book of Paleontology, by Karu A. von ZITTEL, translated
and edited by CuHartes R. Eastman. Vol. I, Part II, pp.
353-700, with 883 wood-cuts. Macmillan & Co., 1899.

After an interval of more than three years since the appearance of
Part I, the invertebrate portion of Zittel’s Paleontology is at last brought
to a conclusion. The plan and scope of this work was discussed at
length in a review of Part I, which appeared in this JouRNAL for Octo-
ber 1896; hence it is only necessary to repeat here that the English
edition is acomposite production, much of Zittel’s text being discarded
and replaced by original contributions from a dozen different authors,
whose names are given on the title-page.

82 REVIEWS

The Grundziige der Paldontologie, which forms the basis of the pres-
ent work, is an essentially modern, useful, and very compact treatise. It
compasses within 900 odd pages the whole field of paleozoGlogy, rather
more than one half of the space being devoted to invertebrates. The
descriptions of genera are brief but to the point, the illustrations
numerous, and the arrangement simple and well-balanced. These are
salutary features for any elementary text-book to possess, and the writ-
ings of von Zittel have set a high standard for other authors to emu-
late.

As compared with the original, we note in the first place that the
English edition devotes about 200 more pages to the invertebrates,
and is enriched by nearly 100 new figures. Over 4600 generic names
are enumerated in the index, being about 1200 in excess of the inver-
tebrates treated in the German edition. The amount of enlargement
is therefore considerable, and the new genera introduced are mostly
those which are of importance in American and British strata.

All the generic diagnoses are of necessity very brief, and large
numbers of names are cited without definition, simply as an index to
their family position, or degree of family differentiation. Typical or
otherwise interesting forms are treated more at length, and in some
instances type-species are listed ; but the definitions of families and
larger groups are as a rule succinctly yet carefully stated. The book
serves as an excellent guide for orientation over the different groups
and as a catalogue of the more important genera, but does not permit
of the identification of less important genera without the aid of special
literature. In compensation for this, copious bibliographies are
inserted under nearly every caption, those for the Cephalopods and
Trilobites being especially complete and all of them brought strictly
up to date.

Many radical changes are to be observed in the classification, the
responsibility for which, we are told in the preface, lies with the
revisers of the different sections. The rearrangement of Pelecypod
families and genera by Dr. W. H. Dall is in accordance with the latest con-
ceptions of this eminent conchological authority. Great emphasis is laid
by Dr. Dall on the distinctness of family groups, and many well-known
genera are taken by him to represent types of new families, or sub-
families. Noris Dr. Dall alone in this tendency toward elevation of
families out of generic characters ; it seems to be becoming more and
more the fashion in all branches of systematic biology, and probably

REVIEWS 83

the most remarkable illustration of all is to be seen in Professor Hyatt’s
new Classification of Cephalopods. The chapters on Nautiloids and
Ammonites, occupying 75 pages, have been entirely rewritten by Pro-
fessor Hyatt, and represent in epitome a life work expended on the
study of these groups. The system followed was proposed in outline
at the Boston meeting of the American Association, two years ago.
Its essential feature consists in the elevation of the three leading
“genera”? of von Buch, Gonzatites, Ceratites, and Ammonites, together
with the Clymenoids of Giimbel, into as many different suborders,
and in addition to these, several entirely new ones are recognized
among the Goniatites and Ammonites. A large number of genera are
made the types of independent families, and the prevailing feature
throughout is the comparison of young stages of specialized forms
with the adult of primitive types. As the entire life history of
Ammonites and other groups are recorded in the progressive changes
taking place in the shell, this class of organisms is especially well
suited for comparative investigations based on the principle of accel-
lerated development.

The chapter on Trilobites is from the pen of Professor C. E. Beecher,
our leading authority on this group. The treatment is much fuller
than in the original, and a considerable number of new figures are
added. As inthe Ammonites it is of prime importance to compare the
ontogenetic stages, and this furnishes the key to the new classification of
Beecher, since adopted by Cowper, Reed, Bernard, and others, although
opposed by Pompeckj. ‘Trilobites are here accorded the rank of a
separate subclass, all other crustacean forms being set off against them
under the title of Eucrustacea. The latter have been revised for the
present work by Professors J. M. Clarke and J. S. Kingsley, with the
exception of the Ostracoda, which are accredited to Mr. E. O. Ulrich.
A noteworthy point consists in the removal from Crustacea of the
Merostomata, including Limulus, the Eurypterids, etc., and associat-
ing them with the Arachnids under the head of the Acerara, of Kings-
ley. This step, it is believed, will eventually be acquiesced in by most
specialists on these groups. Altogether, the chapters on Arthropods
show evidence of most careful revision, and are well-balanced as
regards space.

We come lastly to the chapters on Arachnids, Myriopods, and
Insects, which have been revised and slighly enlarged by that inde-
fatigable paleoentomologist, Professor S. H. Scudder. Save for being

84 REVIEWS

simpler and briefer, the treatment is much the same as that followed
in the Handbook of von Zittel, the chapters in question having been
prepared for that work by the self-same author. Here also new figures
are inserted, a very striking one being Brongniart’s restoration of
Meganeura, a dragon-fly having an expanse of 30 inches between tips
of wings. The book concludes with a complete index of genera and
subgenera.

The present edition of the von Zittel places in the hands of every
English-speaking student a good elementary text-book that has long
been needed. It is significant that in the “ Eastman translation” so
much American material has been introduced, and that so much
revision has been done by American specialists.

Regarding the work as a whole we may repeat what was said of the
first part, that educators in general owe to Dr. Eastman a deep debt
of gratitude for providing our college and higher schools with a “ trans-
lated, revised, and enlarged edition” of the best manual of paleon- |
tology that has ever been written. Professor von Zittel is to be
congratulated, not only for the improvement presented by his new
elementary text-book, but also, as shown by the results, for having
entrusted the preparation of the translated edition to such excellent
hands. CHARLES R. KEYES.

The Gold Measures of Nova Scotia and Deep Mining. By E.
R. FartpauLt. Canadian Mining Review, March 1899,
Pp. 11, with 6 plates.

E. R. Faribault, of the Canadian Geological survey, has lately
announced the results of fifteen year’s work on the gold measures of
Nova Scotia. These results are of great interest, both from a scien-
tific and economic standpoint.

The gold measures of Nova Scotia are confined to the meta-
morphic Lower Cambrian quartzites and slates, forming a belt along
the Atlantic coast from to to 75 miles wide. Intruding these rocks
are large masses of granite occupying nearly a third of the superfices
of the province. ‘These were intruded in Silurian time, after the fold-
ing of the strata and deposition of the gold-bearing quartz, and need
not be considered. The originally horizontal quartzites and slates have
been folded into a series of huge undulations roughly parallel with
the seacoast. The amplitude of the folds varies considerably, but

ry

REVIEWS 85

the average is about three miles. A section of 35 miles across the
gold measures gives eleven anticlines. These folds have been greatly
flexed in a direction transverse to the closer folding, so that they form
long domes. In the folding, the upper strata have slipped upward
on the lower strata, these movements taking place largely along the
soft slate layers between the hard quartzite layers. This has resulted
in compression along the sides of the folds and the formation of open-
ings along the crests.

Gold-bearing quartz has been deposited in the Openings near the
crests of the domes formed by the slipping of the layers. The veins
thus deposited thin out rapidly along the limbs of the folds, but keep
their size along the pitch for some distance, though finally pinching
out. Where the folding has been close and the legs of the anticline
form an angle of less than 45°, the large bodies of quartz on the anti-
cline are called saddle reefs, the name given to such formations in
Australia.

As yet no general operations have been carried on to any depth
through the arch core of the folds in Nova Scotia, although at various
places a number of veins have been found. However, from analogy
with the Australian gold-bearing veins occurring in a similar manner,
it is believed that the quartz veins in Nova Scotia will be found to
recur many times in depth.

The laws governing the position and extent of the zones of quartz
veins, as well as the laws governing the position and extent of the
“pay streaks” within the veins, are given in detail.

This work of Mr. Faribault’s will be of immediate practical advan-
tage to mining men, some of whom have already testified to its
accuracy and value. It is another instance, lately of frequent occur-
rence, of geological work done from a purely scientific standpoint
having direct economic value.

From a scientific standpoint also, the results are of interest as
illustrating a principle of ore deposition. In many districts, and par-
ticularly in the Lake Superior District, it has long been known that
ore deposits were partial concentrates in pitching troughs by decending
waters. Van Hise has lately enunciated the principle that the openings
in arches or pitching folds are favorable places for the concentration
of ore deposits by upward moving waters. The formation of the gold-
bearing veins of Nova Scotia seems likely to have occurred in this Way.

Cakes:

86 REVIEWS

Maryland Geological Survey, Vol. III, Baltimore. The Johns
Hopkins Press, 1899.

This volume consists of the application of geology to the ‘per-
manent and economical improvement” of the roads of Maryland. It
consists of 461 pages and 80 pages on ‘‘ Laws of Maryland relating to
highways.” There are 35 plates, including 14 maps, and 38 figures.

The state geologist, Professor William Bullock Clark, contributes
the Preface, Part I, Introduction, and Part II, ‘‘The Relations of
Maryland Topography, Climate and Geology to Highway Construc-
tion.”’ The author discusses the ‘‘ dependence of the highways upon the
surface configuration of the land,” and their dependence upon the
underlying formations; the effects produced upon the roads by tem-
perature changes, precipitation and winds. He gives the areal distri-
bution of the various geological formations of the state, accompanied
by amap, and with a hint to roadmasters to make use of the information.
Then follows a discussion of the road materials of the state and their
relative values for road building.

Part III, “ Highway Legislation in Maryland, and its Influence on
the Economic Development of the State,” is contributed by St. George
Leakin Sioussat.

Part IV, “The Present Condition of Maryland Highways,” and
Part V, ‘“‘Construction and Repair of Roads,” are by Arthur Newhall
Johnson.

The condition revealed in Part IV amply justifies the Survey in its
undertaking to direct attention to the need and the methods of
improvement. Yet Maryland has some excellent highways, and the
average condition of its roads is perhaps as good asin most of the states.
On the other hand Massachusetts and Connecticut are states which
are noted for their good roads. In Part V Mr. Johnson gives practical
instruction on grading, drainage, and surfacing which will be of great
service in road-building,

The following Parts, VI, VII, VIII, are by Harry Fielding Reid.
Part VI treats of the “‘ Qualities of Good Road-Metals and the Method
of Testing them.” In this chapter Professor Reid deals with the fol-
lowing series of laboratory tests of materials, viz., microscopic test ;
abrasion test; crushing test; cementation test. The results of these
tests upon various rocks are illustrated. Part VIII, relative to ‘‘ The
Advantages of Good Roads,” is adapted to awaken an interest in road
improvement.

REVIEWS 87

If the people of Maryland shall become convinced that, in addition
to incidental advantages, “‘a sum in the neighborhood of three million
dollars would be annually saved by improving the important roads of
the state,” there will be no difficulty in getting appropriations for road
building and repairs. The volume will exert a wide influence for the
betterment of the roads of the country. As a piece of bookmaking it is
exceptionally good. ‘The type is clear, the illustrations are apt and
well-made. The Survey is to be congratulated upon presenting in
such excellent form a volume replete with valuable information and
suggestion. James H. SMITH.

Maryland Weather Service, Vol. I, Baltimore. The Johns Hop-
kins Press, 1899.

The Maryland Weather Service is conducted under the auspices of
the Johns Hopkins University, the Maryland Agricultural College and
the U. S. Weather Bureau.

In Part I, Introduction, Professor William Bullock Clark gives a brief
history of the State Weather Service and presents “ lines of investigation
pursued by the Service.”’ These are topography, physiography, mete-
orology, hydrography, medical climatology, agricultural soils, forestry,
crop conditions, flora, and fauna. He also enumerates the previous
publications of the Service.

Part II consists of “A General Report on the Physiography of
Maryland, by Cleveland Abbe, Jr. Professor Abbe discusses physio-
graphic processes in general and takes up briefly each of the physio-
graphic provinces of the state. A study of stream development of the
Piedmont Plateau leads to the conclusion that *‘‘The streams of the
eastern division of the Piedmont Plateau have been superimposed from
the formerly more extensive Coastal Plain cover.”

Thus the explanation of McGee is confirmed by detailed field
work—at least in the eastern part of the plateau. On page 132, Pro-
fessor Abbe uses the phrase ‘‘ Topographic Valences of the Rocks.”
The word ‘‘valence”’ in this connection is not defined, but imme-
diately following the heading quoted the author speaks of the “ differ-
-ent degrees of resistance which they [rocks] offer to weathering and
erosion.”’ These resistances appear to be what is meant by the term
“‘valences.”” Since valence is used in a quite different, but definite,

PeZOs

88 REVIEWS

sense in chemistry; and since it has still another meaning in biology,
we doubt the wisdom of giving the word a third technical meaning in
geology. And if it means resistance to denudation the coining of a
new term does not seem to be demanded.

Part III consists of a “‘ Report on the Meteorology of Maryland,”
by Cleveland Abbe, F. J. Walz, and O. L. Fassig. Professor Abbe
takes up Dynamic Meteorology and its Applications , Climatology and
its Aims and Methods, and Apparatus and Methods. Among many
suggestive topics we note with approval the emphasis put upon “ Paleo-
climatology” —a subject that is receiving increasing attention on the
part of geologists. Professor Abbe strongly states the case when he says,’
“Geology is primarily a study of the influence of the overlying atmos-
phere upon the earth beneath. It is, therefore, an essential part of the
study to understand the climates and the changes 1n climate that have pre-
vailed since the earth began its annual course around the sun and its diur-
nal revolution around its axis. The study of modern climates must be
considered by the geologists as simply an introduction to the equally
important study of ancient climates and the work done by, them eae Dire
Fassig presents “A Sketch of the Progress of Meteorology in Maryland
and Delaware.” Mr. Walz gives an “‘ Outline of the Present Knowl-

edge of Meteorology and Climatology of Maryland.” The weather —

maps, showing types of weather in various places and seasons are well
selected and are very instructive. There is a chart showing normal
temperature and pressure for Maryland, including Delaware and the
District of Columbia for each month of the year; also one each for
spring, summer, autumn, winter and for the year. There are also
many tables for reference.

The volume is a handsome one of 566 pages, 54 plates, some of
which are colored, and 61 figures. All of the illustrations except
Plate XXXV are pertinent to the subject discussed and add much to
the value of the volume. Plate XXXV is a picture of the office of
the Weather Bureau at Baltimore. It adds nothing of scientific value
and would therefore better have been omitted. It seems ungenerous
to mention so small a matter, for the volume is presented in an
almost faultless form both as to subject-matter and as to mechani-
cal execution. James Hi. SMITH.

SIPS AOU.

oor

REVIEWS 89

Principles and Conditions of the Movement of Ground Water. By
FRANKLIN Hrram Kino, with a theoretical Investigation of
the Motion of Ground Waters, by CHARLES SUMNER
SUICHMER. | Lxt. Nineteenth Anna wep, US: Geol: Survey,
Pare 1) 1809) pp. Ixi-- 3384)

This important paper bears throughout evidences of the painstak-
ing industry that marks all of Professor King’s work. It deals first
with general considerations relative to the amount of water stored in
the ground in different kinds of rock. For the Dakota sandstone he
assigns 15 to 38 feet of water for every 100 feet in thickness of the
rock. The water in the Potsdam sandstone of Wisconsin and
adjoining states he makes equivalent to an inland submerged sea
having a mean depth of 50 to 190 feet of water for the area occupied.
In regard to the’superficial soils and sands, Professor King gives more
detailed data, as this lies in his special field of investigation. A saturated
sand carries from 20 to 22 per cent. of its dry weight of water, while the
soils and clays range from these values all the way up to 40 and even
50 per cent. of their dry weights. “‘Since a cubic foot of dry sand
weighs from 102 to 110 pounds, while soils, clays and gravels range
between this and 79 pounds, we have a ready means of expressing
quantitatively the water which is continually stored in this mantle of
loose material when it lies below the plane of saturation.” Ina table
of actual determinations where loamy clays and very fine sandy soils
are involved, 2 feet of water in 5 feet of soil below the horizon of sat-
uration are shown. When soil does not lie below the plane of satura-
tion it usually contains 75 per cent. of the amount required for full sat-
uration, except during dry times when a surface layer of one to five feet
thick falls below this. Even where the plane of saturation lies below
a large thickness of soil there is still a large storage capacity for
water.

In rocks other than sandstones and soils the percentage is usually
very much smaller. Its cumulative magnitude is indicated by the state-
ment that so small an amount of water as 0.0023 of the weight for 5000
feet of the earth’s crust is large enough to form a continuous sheet
about the globe 30 feet deep. It is believed that water penetrates the
crust to depths even exceeding 10,000 feet. Reckoned at 1 per cent.,
with a specific gravity of rock of 2.65, the amount contained would be
a layer 265 feet thick. Of course the amount in the upper horizons is

go REVIEWS

relatively large and that in the lower very small. An estimate of this
kind gives an impression large or small according to the point of view.
Regarded by itself, it is large, but compared with the whole hydro-
sphere it is but a small factor and does not very appreciably add to the
oceanic volume. It probably does not amount to so much as the prob-
able error in the estimation of the volume of the ocean and other
superficial waters. If the water of hydration be added to it, the state-
ment may not improbably still hold true.

In the treatment of the general movements of the ground water
three categories are recognized: (1) Gravitative, (2) thermal, and (3)
capillary movements. The oscillations in the flow of springs and arte-
sian wells are illustrated by autographic records and their relations to
barometric changes demonstrated. Even the sudden barometric
changes accompanying a shower are sometimes sharply. recorded.
Diurnal changes in temperature are shown to effect thé rate of seepage.
This is attributed chiefly to the indirect effect of the temperature
through the expansion of the gases in the soil. Movements of ground
water are ascribed to rock consolidation and crust deformation. Of
the 25 to 50 per cent., by volume, of water inclosed in the sediments,
when first laid down, a considerable part is forced out as the sediments
settle into greater compactness, and finally pass into indurated rock.
By an ingenious device on automatic flow from the base to the top of
a cylinder of settling sediments was secured against a head of six inches.
In the dynamic consolidation of rocks, a still larger per cent. of the
inclosed water is forced out. The growth of grains and the filling of
pore-spaces is a concurrent source of expulsion of water. Limestones
as now taken from the quarries have, as a rule, a pore-space varying
from less than 1 per cent. to 7 or 8 per cent. at most; so that the
final formation of every 1000 feet of compact limestone means an ex-
pulsion of water from these beds during the process of growth and con-
solidation amounting to not less than one fourth, and possibly as
much as one half, of the present volume of the rock.

For the capillary movements of ground water recourse must be had
to the paper itself, as the tables cannot be briefly and adequately sum-
marized.

The configuration of the ground water surface is illustrated by
contour maps and the flow dependent on this configuration diagram-
matically indicated. The changes in the configuration that result from
precipitation are shown by tables and by diagrayns.

REVIEWS gl

Then follows an account of an elaborate series of investigations of
the flow of water through soils, sands, rocks, and other porous media.
These are much too extended to be reviewed in detail. They furnish
data of prime importance to studies in irrigation, water supply, and
various other inquiries that involve the size of grain, the pore-space, and
the various elements of resistance to percolation. The industrial as
well as the scientific value of these determinations, with which are
collated those of others, is obvious.

The value of the experimental study of Professor King is greatly
enhanced by the theoretical investigation of the motions of ground
water by Professor Slichter. The treatment is mathematical and can
be read only by those who are familiar with its elegant language. The
excellent illustrations, however, translate some of the more vital parts
into the vernacular. Those which relate to the interferences of flows
into artesian and other wells are especially instructive.

Ee:

Les Lacs Francais. Par ANDRE DELEBECQUE. Ouvrage cou-
ronné. par l’Academie des Sciences. 436 pp., 22 plates,
and 153 figures in the text. Accompanied by an atlas of
10 maps. Paris: 1808.

This elaborate work is divided into ten chapters, and a brief outline
is here given of the substance of each:

I. Dzstribution.—Most of the lakes of France are in the moun-
tains, the Alps, the Juras, the Vosges, and the Pyrennees ; but there are
some in the central plateau, some along the coasts, and still others
which do not admit of ready classification. The total number of
lakes given is between 460 and 470, but many of them are so small
that in our own country they would be called ponds.

II. Depth.—The second chapter has to do with the depth of the
lakes, and the chartings of the soundings.

Ill. Description—The third chapter is a description of the princi-
pal lakes, the description taking account of the depth, the area, the
position, etc. Contour maps of the basins of more than forty lakes
are given on the plates. Of lakes more than 25 meters deep, there
are thirteen in the Alps, eleven in the Juras, two in the Vosges, eight
in the central plateau, twelve in the Pyrennees, and one on the coast
of the Mediterranean, forty-seven in all. Of lakes more than 1000

92 REVIEWS

hectares (approximately four square miles) in area, there are in the
Alps two, in the Juras one, along the Atlantic coast four, and along
the Mediterranean coast two. Even of lakes more than 250 hectares
in area (approximately one square mile) there are but thirteen. It
will be seen therefore that most of the lakes are very small. The tables
show that the depth of many of them is great in comparison with their
area.

IV. Zopography.—The fourth chapter deals with the character of
the topography and relief of the lake bottoms. Few of the lakes have
great depth. Lake Geneva has a maximum depth of <4, of its
length and = of its width, but these ratios are exceeded by many
of the smaller lakes. The deepest lakes in proportion to their area
are in the Pyrennees. Here Lac Bleu has a depth of 120 meters with
an area of but 47 hectares. In the lake bottoms are recognized (a) the
marginal plains, partly wave cut and partly wave built; (4) the tallus
slopes (a talus slope of 87° runs down to a depth of 42 meters in one
case, and aslope of 63° to a depth of 100 meters in another), and (c)
the bottom flats. In the large lakes the sensible flat (or flats) at the
bottom is some considerable fraction of the total area. In Lake
Geneva the bottom flat of an area one twelfth of the total area of the
lake has a relief of less than five meters. These flat bottoms are nat-
urally more distinct in the large lakes than in the small ones. Cer-
tain more or less accidental features are recognized in the topography
of the lake bottoms. Here are classed deltas, submerged valleys,
ravines, hills and islands and funnels. The latter are rare, and repre-
sent either places where springs enter the lake, or where sub-surface
drainage escapes. Two or three remarkable instances are cited, espe-
cially in Lac d’Annecy.

V. Nature of the bottoms.—The nature of the bottom is the topic of
the fifth chapter. The bottom consists in part of alluvium, and
in part of the rock in which the basin occurs. ‘The alluvial mate-
rial is found to vary both microscopically and chemically with the
nature of the rock of the basin. Numerous tables of results are given.
The following conclusions are reached: (a) The material at the bot-
tom of the lake varies with the rock. In limestone basins calcareous
matter dominates, while in basins in siliceous rocks, quartz is most
abundant. (4) The mean composition of the sediment in the lake is
not the same as the mean composition of the rocks in the basin. For
example, the sulphates are essentially absent in certain lakes whose

REVIEWS 93

affluents flow over gypsum, or whose shores are partly of gypsum. On
the other hand, sulphuric acid is found in small quantity in lakes
where there is no gypsum adjacent. Again, calcium is abundant in
basalt, but not in the sediment in lakes in basaltic regions. Alka-
lis are plentiful in granitic rock, but only sparingly present in the
lakes in granitic basins. The alkalis and alkaline earths are carried
off in solution, chiefly as carbonates, while the silica stays behind and
is thus concentrated. (c) The composition of the sediment varies in
different parts of the same lake.

Sediment is absent in the bottom of the lakes where the slope is
too steep for it to rest,in general where the slope is over 45°, and
where local conditions have prevented deposition, as where springs
enter or where drainage flows out. Sediment is also absent where cur-
rents have been effective at the bottom.

VI. Supply and loss.—A chapter is devoted to the supply and loss
of water, and to the variations in the levels of the lakes. An interest-
ing section is given to the average length of time which water stays in
lakes. This is determined from the volume of the lake, and the rate
of outflow. Thus in Lake Geneva, it is found that the average stay of
water in the lake is eleven years and seventy-three days; in lake
d’Annecy three years and one hundred and thirteen days; in Lake
Chaillexon five days. Many other calculations are given, all of which
tend to show that the duration of the stay of water in lakes is extremely
variable. Lakes with surface outlets are found to change their levels
but slightly. Data on this point seem somewhat imperfect, but the
maximum known fluctuation in the case of lakes having surface outlets
is three meters. In lakes having sub-surface outlets, fluctuations of
level are far greater. They appear also to be greater for small lakes
than for large ones. Thus the level of Lake Chaillexon between
August 19, 1892 and December 31, 1895, fluctuated sixteen meters.

VII. Zemperature.—The tables of temperature given show that the
water at the bottoms of the deep lakes varies very little, and that it is
near the temperature of greatest density all the time. The tables
show that in most lakes there is a well-defined zone which separates the
warm (during most of the year) water above from the cold water below, the
transition being usually rather abrupt. This zone of transition is rarely
more than twenty meters below the surface, and sometimes not more than
ten. The causes determining temperature are considered. Aside from
(2) climate, the effect of which is obvious, (4) the average depth, (c)

94 REVIEWS

the form and orientation of the lakes, and (d) the sources of supply,
influence their temperature. The form and orientation of the lakes
is of importance in connection with the winds. Lakes which are ori-
ented so as to allow winds to exert their most important influence in
the generation of currents, have their temperature equalized in the
vertical sense, through the return currents. Circulation is thus shown
to be of more importance than conduction in equalizing the tempera-
ture between top and bottom. The rdle of affluents in determining
lake temperatures is very variable. It depends on the size of the
lake, the average stay of the water in the lake, and the nature of the
affluents themselves. Following Forel, the author emphasizes the par-
adoxical fact that the waters of the glacial Rhone raise the temperature
of Lake Geneva, the temperature of the river being notably above that
of the lower part of the lake at all times, while the large amount of
sediment in the river water so increases its specific gravity as to cause
it to descend much below the zone of lacustrine temperature corres-
ponding to itsown. Sub-surface affluents exert an important influence
in their immediate surroundings, or, if the lake be very small, on the
whole volume of water. The temperatures of these affluents being essen-
tially constant, the temperature of the lake is differently affected by
them in different seasons. Lakes are classified by the author, follow-
ing Forel, on the thermal basis, as ¢ropical, temperate, and polar. ‘The
tropical lakes are those whose surface waters do not reach 4° C.; the
temperate lakes are those the surface waters of which are sometimes
below and sometimes above 4°; while the polar lakes are those whose
surface waters never rise above 4°. Of the first class the larger part
of Lake Geneva, and certain salt lakes near the shore are the only rep-
resentatives. To the second class most of the lakes of France belong,
but there are a few representatives of the third class in the Pyrenees,
and in certain other high altitudes.

Chapter VIII deals with the transparency, color, etc., of the lakes.
The lakes are partly blue (few), partly green (the larger number), and
partly yellow (a large number.) ‘The color is found to be influenced
by (a) the dissolved organic substances, such as humic and ulmic acids ;
(6) the presence of vegetable and animal organisms in the water; and
(c) the inorganic sediment. The transparency is found to vary within
a given lake with the season, and with the position of the station. It
is greater in winter than in summer, and increases with increasing dis-
tance from the debouchures of streams. The water of the blue lakes is

REVIEWS 95

most transparent, that of the green less, and that of the yellow
least.

IX. Matter dissolved tn the water of the lakes.—With the exception
of the salt lakes, none of the lacustrine waters contain so much as
one gram of solid matter per liter, and in five cases only does it
exceed .3 gram per liter. There are notable variations in the amount
and kind of dissolved matter depending upon the character of the
basin, and there are notable variations in the same lake in differ-
ent seasons, and in different parts during the same season. In the
summer the warm waters in the upper portions of the lakes are poorer
than the colder waters below, in some of the dissolved substances,
especially Ca CO, and SiO,, while in winter the solutions are nearly
uniform throughout. In general, the lake waters have less solid mat-
ter in solution than the inflowing rivers, showing that dissolved
matter is lost in the lakes. ‘This loss is attributed largely to precipita-
tion, and it seems to be implied that calcareous tufa is of very common
occurrence. This would hardly hold for the greater number of the
lakes in the United States. With reference to dissolved gases, the con-
clusion is reached that the amount of these gases, chiefly CO,, O, and
N, are independent of pressure, but that they increase with depth
on account of the lower temperature. The amount of carbonic acid
gas dissolved far exceeds that of oxygen and nitrogen together,
whether measured by weight or by volume. Little account is taken of
other gases.

X. Geological position and origin.—The classification of lakes in
general is briefly outlined, and the lakes of France fitted to the classi-
fication. Two primary classes of lake basins are recognized : (1) Those
produced by barriers of one sort and another, and (2) rock basins. Of
the barrier basins there are many types, most of which are represented
in France. The barriers are of various types as follows: (1) Land-
sides. Lake basins produced in this way are found in the Alps, the Juras
and the Pyrenees, but are not numerous. (2) ce. No existing lake in
France owes its existence to an ice barrier. One extinct lake is so
classed. (3) Moraines. The moraine of an existing glacier is the
barrier which gives origin to a single lake,— Lac Long in the Alps.
Lakes which owe their origin to moraines of extinct glaciers are numer-
ous and of several classes. Here belong (a) lakes in valleys which
were occupied by glaciers, the moraine forming a dam at the lower end
of the lake. Of this class there are several representatives in the Alps,

96 REVIEWS

the Juras, and the Vosges Mountains, one in the central plateau, and
one in the Pyrenees ; (4) lakes which result from the blocking of a lateral
valley by the moraine of the glacier which occupied the main valley.
Of this there are representatives in the Alps. the Juras, and the Pyrenees ;
(c) lakes which lie in basins occasioned by the irregular deposition of
drift. But two lakes fall into this category, one in the Alps, about which
there is some question, and one in the Juras. In our own country
lakes of this class are more numerous than any other. (4) Lava.
Several lakes, the basins of which are formed by lava dams, are found
in the central plateau. (5) Volcanoes. Two lakes in the central
plateau owe their origin to growth of volcanoes in the bottoms of
valleys. (6) Crazers. Several lakes in the central plateau occupy
craters. (It is not altogether clear why crater lakes should be classified
among the lakes produced by barriers). (7) Azver alluvium. Lakes
formed along rivers by the deposition of alluvium are represented by a
few lakes in the Alps, Juras and along the Mediterranean coast. (8)
Bars. A few lakes on the coast owe their origin to the construction of
bars which shut off a portion of the sea water, leaving inland basins.
(9) Dunes. There are several lake basins completed by dune barriers
along the Atlantic coast.

Of the lakes which occupy basins in the rock, one group owes
its origin to internal forces. In this category belong the basins pro-
duced (1) by violent volcanic disturbances, such as explosions, of which
there are several examples in the central plateau; and (2) lakes pro-
duced by secular movements. To this class belong several lakes in the
Alps (Geneva and d’Annecy), and in the Juras, though concerning the
origin of the latter there seems to be some question. Of the lake basins
originating through the action of external forces, there are (a) those
resulting from solution effected by underground waters, represented in
the Alps and along the Atlantic coast, in the Juras, along the Mediter-
ranean, and in one or two other places; (4) lakes due to erosion of
rock along fissures, as where a fissure crosses a watercourse; and
(c) basins due to excessive local erosion by the ice, represented in the
Alps by several examples, in the Juras by one possible example, in
the Vosges by one, in the central plateau by several, and in the Pyrenees
by a considerable number. Here belongs Lac Bleu, of extraordinary
depth. It is probable that in the production of many of the lake
basins more than one factor has been involved.

REVIEWS 97

XI. The life history of lakes—After a consideration of the various
causes which may bring the life of a lake to an end, the history of a
few of the principal lakes of France is sketched. The level of Lake
Geneva has been lowered about 30 meters since the glacial time. It
had one stationary level between the highest and the present levels,
when the water stood ro meters higher than now. The other lakes
especially considered are Bourget, which has also been lowered in post-
glacial time, and d’Annecy, which was formerly 15 meters lower than
now. ‘The rise was occasioned by alluvial deposits in the valley of the
Fier, to which the outlet of the lake flows. These deposits have
dammed the exit. The history of Lacs de Saint Point and Remoray
—in the Juras—is also outlined, the interesting point being that they
were formerly one lake, now divided into two by the growth of a
delta completely across the narrow basin. The growth of deltas seems
to have played a large part in the history of many of the mountain
lakes. This is the natural course of events where torrential streams
debouche into the standing water. Many other lakes appear to have
had their areas greatly diminished by similar processes. Reference is
also made to certain extinct lakes, and the criteria by which their for-
mer existence is recognized are briefly given.

The figures in the text of the volume are largely half tones, which
unfortunately, cannot be said to be of more than medium grade. It
could have been wished also that the few maps of the text which show
features other than the topography of the lake bottoms, could have
been clearer. On the whole they have so much ink, that it is difficult
to find the points sought. It is always a serious problem to make a
map clear, and at the same time get a great deal on it, and in this case
the difficulty has not been overcome.

Ie 1D. Se

On the Building and Ornamental Stones of Wisconsin. By. E.R.
eciiLion7, IID, Wilkichisom, WIS. W808, Jeo. sexi ae blz.
Bull. No. 4. Economic Series No. 2 of the Wisconsin
Geological and Natural History Survey.

Dr. Buckley’s report is one of the most compendious volumes on
the subject of building stones published in recent years. Of the three
parts into which the subject-matter is divided the first treats of the
demands, uses, and properties of building and ornamental stones in
general. This is a valuable though brief discussion of the subject.

98 REVIEWS

Part II, which forms the bulk of the volume, begins with a chapter
on the geological history of the state, followed by a detailed descrip-
tion of the different quarry-areas. The igneous and metamorphic
rocks are first enumerated and described, and the author clearly shows
the variety as well as the architectural beauty and value of the granitic
rocks of the state. The only metamorphic rock mentioned is quartzite.

The sandstones are divided into three classes, partly on a geo-
graphical and partly on a geological basis. The first class includes
the northern Potsdam sandstone, comprising what is ordinarily known
as the Lake Superior brownstone, which apparently differs quite
markedly from the sandstones of the southern Potsdam area and the
St. Peter’s formation included in the second and third classes. Neat
sketch maps show the location of the quarries with reference to the
markets and the transportation facilities. The limestone quarries are
conveniently divided on a geological basis into (1) the Lower Mag-
nesian, (2) the Trenton, and (3) the Niagara.

Chap. vil relates to the areas from which suitable stone for dif-
ferent uses may be obtained, such as building stone, bridge stone,
paving blocks, etc. - It has a direct economic bearing that will no doubt
be appreciated by architects, builders and dealers in stone.

In the next chapter there is a discussion of the results of physical
tests which are conveniently summarized at the end of the chapter ina
series of thirteen tables. ‘The crushing strength may really have little
significance to the scientist, but has great weight with the architect.
In this respect the Wisconsin granites and limestones have shown sur-
prising results. The excess of strength of the Wisconsin granite over
that from other states is possibly not so great, however, as the tests
might lead one to believe. Granting that Gilmore’s formula is incor-
rect, it is not conclusive proof that a large cube is not stronger than a
small one in a ratio greater than the comparative areas of the faces. It
might have been better to have given the dimensions of the cubes of
the granites tested from other states along with the figures quoted and
permit the reader to draw his own conclusions.

One of the most important sections of the report has to do with
the effects of freezing and thawing on the strength of building stones.
Numerous experiments have been made leading to the conclusion that
freezing and thawing, continued for a considerable period, lessen the
strength of rock, and that the loss in strength is in a general way pro-
portional to the crushing strength of the rock. In other words, the

REVIEWS 99

loss of crushing strength is greater in rocks in which the porosity is
low and the size of the pores small, than in rocks in which the pore
space is high and the pores large. This conclusion is diametrically
opposed to that which is popularly current. The explanation of this
unexpected result is that in the case of rocks where the pores are large
the included water is given off with sufficient rapidity to avoid the
evils of freezing, while in the case of close-textured rocks which are
saturated when frozen, the water does not escape, and the injury to
the rock is greater. This is a point of great practical value, as well as
of theoretical interest. The results of the experiments are given in
detail in tabulated form. Part II also contains a set of tables in which
are given the results of the various other physical tests to which the
building stones of Wisconsin have been subjected.

Part III is an appendix in which composition, kinds of stone, and
rock structures are discussed.

The form of the report is a convenient one, the binding is neat
and attractive, the illustrations are numerous and for the most part
well chosen. A carefully prepared map of the state is folded in the
text. An attractive feature is the representation of the stones in their
natural colors. No verbal description could arrest the attention so
effectually or give the reader so vivid an idea of the beauty of the stone,
as these artistic plates. If the printer is not at fault, however, one
might wonder why the beautifully colored granite on Plate XII should
be called gray.

The person who can write a perfect report on building stones has
not yet attempted it. In Dr. Buckley’s report there are some points
which some of his readers might wish to change. Some are matters
of personal taste and all are of somewhat minor importance compared
with the much valuable matter forming the body of the report.
Petrographers may not all agree entirely with the distinction between
gabbro and diabase (p. 447). Some of the readers may not agree with
the relative importance placed upon the different cements in sand-
stone given on p. 450, or with the conclusions about the use of quartzite
on p. 455. All those who might agree with the author that “the joints
in igneous rocks are more numerous than in the sedimentary” might
not agree with him that it is ‘‘owing to the greater length of time
through which they have been subject to dynamic action” (p. 459).

The report represents a vast amount of careful and conscientious
work on the part of Dr. Buckley and will no doubt prove a valuable

100 REVIEWS

handbook in the stone trade of Wisconsin. While it is prepared
primarily in the interests of the stone industry of Wisconsin, it has
much of general interest to persons outside of the state, and both Dr.
Buckley and the director of the Wisconsin Geological and Natural
History Survey are to be congratulated on presenting to the public
such an interesting, attractive and valuable contribution on the sub-
ject of building stones.
fee Ox lal.

Irrigation and Drainage. Principles and Practice of their Cultural
Phases Byes Tih KinGs, ihe NuraltSciencerSeries mama
Macmillan Company, pp. 502, 8vo. 1899. Amply illus-
trated.

In this work there is brought together a vast amount of experi-
mental and experiental data relative to the physics of soils and their
relations to water and air. ‘These data are given in both their ana-
lytical form in the shape of tables, diagrams, and other modes of scien-
tific expression, and in their concrete industrial form as exemplified in
growing crops and in drainage and irrigation appliances. The treat-
ment is very clear and specific and at the same time very compact. It
is a conspicuous example of mu/tum in parvo, if 500 close-set pages do
not make the expression inapplicable. The author has personally
studied the irrigation systems of Europe as well as those of this coun-
try, and has himself conducted careful experiments bearing on the
fundamental principles involved. While thoroughly practical in its
bearing, the treatment is firmly controlled by the scientific spirit. It
is an admirable blending of good science and good technology.

DRAKE (G.

Ihe Coos Bay Coal Field, Oregon. By JosEpH SiLas DILLER.
Extract from the Nineteenth Annual Report of the U. S.
Geol. Survey, 1897-8, Part III, Economic Geology.

This paper deals almost wholly with economic interests of a very
local character ; and yet it is not without some facts of general interest.
It is a description of a coal field of very limited extent situated on the
coast of Oregon 200 miles south of the Columbia River. The coal is
of Eocene age. Fossils of fresh and brackish water type are found in

REVIEWS IOI

immediate connection with the coal, while marine shells are found in
the sediments separating the beds.

The seams contain true coal and “‘ pitch coal.”’ The true coal is of
good quality, containing little ash. Much of it is “fat,” containing as
high as 66 per cent. of volatile matter. The ‘ pitch coal” is found in
veins and irregular masses in or near the true coal. The latter part of
the paper is devoted to a discussion of the “ pitch coal” by William C.
Day, who concludes that it is an asphalt, as it shows none of the char-
acteristics of coal.

Whe 40, Jb,

RECENT FUBLICATIONS

—Alabama Geological Survey. Map of the Warrior Coal Basin, with
Columnar Sections. By Henry McCalley, Assistant State Geologist.
Atlanta, 1899.

— ANDREWS, WILLIAM. The Diuturnal Theory of the Earth. Published by
Myra Andrews and Ernest G. Stevens. New York, 1899.

—American Association for the Advancement of Science, Proceedings of.
Forty-eighth Meeting, Held at Columbus, Ohio, August 1899. Pub-
lished by the Permanent Secretary, December 1899. Easton, Pa.

—BERENDT, G., K. KEILHACK, H. SCHRODER und F. WAHNSCHAFFE, Von
der Herren. Neuere Forschungen auf dem Gebiete der Glacialgeologie
Norddeutschland erladutert an einigen Beispieler zugleich erschienen als
Fiihrer fiir die Excursionen der deutschen geologischen Gesellschaft in
das norddeutsche Flachland vom 28. September bis 5. October 1898.
Separatabdruck aus dem Jahrbuch der kénigl. preuss. geologischen
Landesanstalt fiir 1897. Berlin, 1899.

—BRANNER, J. C., and C. E. GipMAN. The Stone Reef at the Mouth of the
Rio Grande do Norte, Brazil. From the American Geologist, Vol.
XXIV, December 1899.

—BRANNER, J.C. The Manganese Deposits of Bahia and Minas, Brazil.
A Paper presented to the American Institute of Mining Engineers at
the California Meeting, September 1899. Author’s Edition. Leland
Stanford, Cal., 1899.

— CARTER, Oscar, C.S. Coastal Topography of the United States. From
the Proceedings of the Engineers’ Club of Philadelphia, Vol. XVI,
October 1899. No. 5.

—Darton, N. H. Triassic Formations of the Black Hills of South Dakota.
Bulletin Geological Society of America, Vol. X, pp. 383-396. Pls. 42-44.
Rochester, N. Y., 1899.

—DItuer, J. S. The Coos Bay Coal Field, Oregon. Extract from the
Nineteenth Annual Report of the Survey, 1897, Part II, Economic
Geology. Washington, 1899.

—EASTMAN, C. R. Jurassic Fishes from Black Hills of South Dakota.
Bulletin of the Geological Society of America, Vol. X, pp. 397-408.
Pls. 45-48. Rochester, December 1899.

102

RECENT PUBLICATIONS 103

— GAILLARD, CLAupius. A Propos de l’Ours Miocéne de la Grive Saint
Alban (Isére). Lyons, 1899.

— Geological Survey of the United Kingdom, Memoirs of. The Silurian
Rocks of Britain. Vol. I. Scotland. With Petrological Chapters and
Notes. Geological Survey of Scotland. Glasgow, 1899. Price, I5s.

—HAtt, C. W., and F. W. SarpEsoNn. Eolian Deposits of Eastern Minne-
sota. Bulletin Geological Society of America, Vol. X, pp. 349-360.
Pls. 33-34. Rochester, 1899.

—Hircucock, C. H., LL.D. William Lowthian Green and the Theory of
the Evolution of the Earth’s Features. From the American Geologist,
Vol. XXV. January 1900.

—Hoxmes, W. H. Preliminary Revision of the Evidence Relating to
Auriferous Gravel Man in California. From the American Anthropolo-
gist (U. S.), Vol. I, January and October 1899.

—Kenmp, J. F. Granites of Southern Rhode Island and Connecticut, with
Observations on Atlantic Coast Granites in General. Bulletin Geo-
logical Society of America, Vol. X, pp. 361-382. Pls. 35-41. Roches-
ter, 1899.

—kKuinG, F. H. Irrigation and Drainage. Principles and Practice of their
Cultural Phases. The Macmillan Company, New York, 1899.

—_KNIGHT, W.C., and E. E. Stosson. The Oil Fields of Crook and Uinta
Counties, Wyoming. Petroleum Series. Bulletin No. 3 School of
Mines, University of Wyoming. Laramie, 1899.

—Kunz, GEoRGE F. Production of Precious Stones in 1898. Extract
from Twentieth Annual Report of the Survey 1898-9. Part VI, Min-
eral Resources of the United States Calendar Year 1898. Washington,
1899.

—MAttettT, F. R., F. G. S., Late Superintendent of the Geological Survey
of India. On Langbeinite from the Punjab Salt Range. Reprinted from
the Mineralogical Magazine, Vol. XII, No. 56.

— Maryland Geological Survey, Vol. III, 1899. Wm. B. Clark, State Geolo-
gist. The Johns Hopkins Press, Baltimore, 1899.

— Maryland Weather Service, Vol. I, 1899. Wm. B. Clark, Director. Johns
Hopkins Press, Baltimore, Md., 1899.

— Moser, Jou. Cur., och N.O. Hoist. De Sydskanska Rulklstensasarnes
Vitnessbérd. 1 Fragan Om Istidens Kontinuitet. Lund, 1899.

—Moutton, F.R. The Spheres of Activity of the Planets. Reprint from
Popular Astronomy No. 66.

104 RECENT PUBLICATIONS

—New York State Museum, Bulletin of. Petroleum and Natural Gas in
New York. By Edward Orton, LL.D. University of State of New York,
Albany, 1899.

—QOyYEN, P, A. Kontinentalglaciation og Lokalnedisning. Alb. Cammermey-
ers Forlag. Archiv for Mathematik og Naturvidenskab. B. XXI, Nr. 7.
Lund, 1899.

—RICHTER, E. Les Variations Périodiques des Glaciers. Quatriéme Rap-
port, 1898. Extrait des Archives des Sciences Physiques et Naturelles,
Th, WINE, wise), (Gemerres

—RoGErRS, A. W., and E. H. L. SCHWARz. Notes on the Recent Lime-
stones on Parts of the South and West Coasts of Cape Colony. Trans-
actions of the South African Philosophical Society.

—Rupzki, M. P. Ueber die Gestalt elasticher Wellen in Gesteinen. IV
Studie aus der Theorie der Erdbeben. Extrait du Bulletin de 1 Acadé-
mie des Sciences de Cracovie, Juillet, 1899.

. — SALISBURY, ROLLIN D., and Wm. C. ALDEN. The Geography of Chicago
and its Environs. Bulletin of the Geographic Society of Chicago, No. 1.
Published by the Geographic Society of Chicago, 1899.

—WoosTER, L. C., Ph.D. Educational Values of the Natural Sciences.
Department of Natural Sciences, State Normal School, Emporia, Kan.

—ZITTEL, Professor D. K. A.v. Zur Literaturgeschichte der alpinen Trias.
Wien, December 1899.

IORI One MOLOGY

[MESSI OAR NILA Cla, SOOO

WIENS, IMKOMIFINCIWAINUIRE, Ov ISIC IDSA ele
GRANOLITES.*

Most petrographers agree that the classification of granular
rocks, if not of lavas, should be based on mineral composition.
This resolves itself practically into the molecular composition.
When we state that a rock is composed of quartz, mica, and
orthoclase in certain definite proportions, we state the relative
proportions of the molecules of which these minerals are com-
posed, and this is true of all other minerals which are made up
of a single molecule. But when we introduce terms such as
plagioclase, which is composed of two molecules in ever varying
proportions, we no longer treat of molecules as such, but of mix-
tures of molecules. It seems quite clear that the molecular
method should be applied throughout, when practicable, and in
calculating the composition of the feldspathic rocks the plagio-
clase should be resolved into the constituent albite? and anor-
thite molecules, and the term plagioclase should not be used.
This is particularly necessary with monzonites and diorites, for it
is clear that if we define typical monzonite as a rock composed
of equal quantities of orthoclase and soda-lime feldspar, we may

«Published by permission of the Director of the U. S. Geological Survey.

2We may treat the soda of the feldspars all as in albite, although some of it may
be in the orthoclase.

Vol. VIII, No. 2. 105

106 Hl. W. TURNER

have orthoclase with basic labradorite, although that must be
rare, or, orthoclase with acid oligoclase. The nature of these
two rocks would be so different as certainly to make us hesitate
to designate them by the same name. In the feldspathic rocks
it seems to me proper to base the classification of these rocks
primarily on the feldspars, and if we subdivide the feldspathic
rocks on the basis of the ratio of the alkali-feldspar molecules
(Or-+ Ab) to the lime-feldspar molecules (An), the true min-
eral and, to some extent, the chemical relations of the rocks
will be brought out, and I think more correctly classify them
than to put the orthoclase, or the alkali-feldspars in apposition
to the albite and anorthite molecules combined. In order to
graphically represent the position of the various rocks under
discussion there is now introduced a table which is self-explana-
tory. In the column represented in the table we have at one
end of the series an alkali-feldspar molecule and at the other
end a lime-feldspar molecule, and the feldspars of rocks may be
said to be composed of one of these molecules or of isomor-
phous mixtures of thesame. The rocks at the head of the column
containing feldspars composed chiefly of orthoclase and albite
may be designated as orthosite (from the French term orthose =
orthoclase) when orthoclase chiefly is present; as anorthosite,?
when anorthoclase chiefly is present, and as albitite when albite
chiefly is present. The rock at the foot of the column, whose
feldspathic constituent is largely anorthite, may be designated
anorthitite.

It is impracticable at the present time, and, for the purpose
of this paper, unnecessary to consider the position in this column
of all the feldspathic granolites; a sufficient number, however,
are introduced to show the result of the method here proposed,
as follows:

Albitite-porphyry or soda-syentte-porphyry.— No. 1521 Sierra Nevada.
Turner. Seventeenth Ann. Rept. U.S. Geol. Surv., Part I, p.727. Composed

3The use of this term will be at once objected to by petrographers since it has
already been used for rocks composed largely of labradorite and more basic feldspars.
It is a question, however, since the term in this sense is a misnomer, if it would not be
well to drop it.

GRANODIORITE

NOMENCLATURE OF FELDSPATHIC GRANOLITES 107

GRANITE
AND
SYENITE

FQUARTZ-
MONZONITE
AND
MONZONITE

QUARTZ-
DIORITE
AND
DIORITE

GABBRO
SERIES

OMNES OF ANMHINS Saccinins shud boleoapkooueebobesuus

-—j-t00o Y% Or. + Ab

ENSUES INO) HEE Sh INIn IRA) EBT ooo eocu ana hamedeee

Aplitetof (Granodiorite, eRation7.or ues eae eee eee eee

Granodiorite | Nios connec at OMe eee ne en

Monzonite from Monzoni3.8:1....... 0
Butte Granite. Average: 3.7/1.............-

Banatite. Average

Amphibole gabbro No, 1970.

Idaho Basin Granite: 2.9:1.

Quartz-micaldionite! Nong 6a arti eee ene
Quartz-diorite. Average; 1.4:1. .

—Division line between Diorite and Gabbro...............

ahiogmcunsi see sae

= Anorthititen escent eeeeenee:

‘90 %

80 %

Vosct
Granitite from Barr-Andlau § 7°9° +--+ ++:+ +--+ -+-------

70 %

-|-60 Y

-[-50 %

‘4° %

30 %

--—boG (109% An)

108 TEh WY, TEQURINTEIR

chiefly of albite with some aegerite (?). Ratio of the orthoclase and albite
molecules combined, to the anorthite molecules, 35: 1.

Afplite.— Average of two analyses of aplites from dikes in the Sierra
Nevada granodiorites. Composed of quartz> orthoclase> albite> anorthite.
Jour. GEOL., Vol. VII, 1899, p. 160. Ratio, 7.8:1. This is the most alkali
rich granite in the Sierra Nevada. The amounts of feldspars here given are
the result of a more exact calculation, and differ somewhat from the amounts
given in the paper referred to. The biotite-granite of my former paper is in
reality a quartz-monzonite, and its molecular composition likewise requires
some revision.

Granodiorite.— Lindgren. No. 103, Pyramid Peak. Amer. Jour. Sci.,
Vol. III, April 1897, pp. 306 and 310. Ratio, 4:1. Composed of ortho-
clase > quartz> albite> anorthite.

Monzonite.— Brégger, from Monzoni, described by him on page 24 of
“Die Eruptionsfolge der triadischen Eruptivgesteine bei Predazzo in Siid-
tyrol,” with a ratio of 3.8: 1. Composed of orthoclase> albite > pyroxene >
anorthite > lepidomelane> hornblende> magnetite> quartz> apatite, zir-
con, etc. This is taken as Brégger’s typical monzonite.

Butte-grantte or guartz-monzonite.—Weed. JOUR. GEOL., Vol. VII, 1899,
pp. 739 and 744. Average of four analyses of the granitic rock at Butte,
Montana. Ratio, 3.7: 1. Composed of quartz> albite > orthoclase> horn-
blende> anorthite> biotite, titanite, and apatite.

Idaho Basin granite-——Lindgren. Eighteenth Ann. Rept. U. S. Geol.
Surv., Part III, pp. 640-641. Ratio, 2.9: 1. Composed of albite> quartz >
anorthite > orthoclase > hyalophane, apatite, titanite, magnetite, and calcite.

Banatite.— Brogger. Average of analyses ‘of five banatites. JOUR.
GEOL., Vol. VII, p. 149. The potash and soda given in the paper referred
to are interchanged in both the average of the banatites and of the adamel-
lites. Ratio, 2.5:1. Calculation approximate.

Granitite—From Barr-Andlau. Rosenbusch. Die Steiger-Schiefer.
Abhandlungen zur geologischen Specialkarte von Elsass-Lothringen, Vol. I,
pp. 147-148. Ratio, 2.5:1. This appears to be the rock referred to by
Brégger on page 62 of his paper on the Monzoni rocks. He states that it
contains 35.5 per cent. of orthoclase; 31.5 per cent. plagioclase (Ab, An;);
24 per cent. quartz; and Io per cent. magnesia-mica. Rosenbusch, however,
in the paper above referred to states that this granitite contains about 27 per
cent. orthoclase, 40 per cent. plagioclase, 24 per cent. quartz, and Io per
cent. magnesia-mica. The rock represented in the table below, therefore, is
Rosenbusch’s Barr-Andlau rock, and not the rock discussed by Brégger on
page 62 of his paper.

Quartz-mica-diorite or basic granodiortte——Turner. Seventeenth Ann.
Rept. U. S. Geol. Surv., Part I, p. 724. Rocks of this type are to be found

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110 Mile Vie INOUSINIII

at a great number of points in the granodiorite areas of the Sierra Nevada.
Ratio, 1.5:1. Composed of albite> anorthite > quartz> orthoclase><bio-
tite, amphibole, etc. Calculation approximate.

Quartz-diorite— Turner. Average of five analyses of quartz-diorite from
the Sierra Nevada. Jour. GEOL., Vol. VII, 1899, p. 149. Ratio, 1.4: 1.
Composed of anorthite> albite> quartz>—orthoclase. In most of the
quartz-diorites there are biotite, hornblende, and accessory minerals present.
Calculation approximate.

Amphibole-gabbro.—No. 1970 Sierra Nevada. Turner. Am. Jour. Sci.
Vol. VII, 1899, p. 297. Ratio, 1:1.5. Composed of amphibole> anor-
thite> albite > orthoclase. There are also present magnetite, pyrite, and
pyrrhotite. Calculation approximate.

Taking the monozite from Monzoni as a typical mozonite
Widn a eti@ or (Omar iNo)e 42 Ain, ie is Clears wine i Wwe
accept the method here proposed the granodiorite No. 103, the
Butte granite, and the Idaho Basin granite are properly quartz-
monzonites. If we likewise place the banatites with quartz-
monzonites, then the granitite from Barr-Andlau, and many of
the granodiorites of the Sierra Nevada will likewise be quartz-
monzonites.

The use of mineralogical terms in naming granolites of
simple composition seems to me very desirable, although it is
not practicable with rocks of complex composition. This can
be done with most feldspathic types as follows:

Orthosite composed chiefly of orthoclase

Anorthosite ‘“ si ‘“ anorthoclase
Albitite GE sf «« albite
Oligosite e “ oligoclase
Andesinite ‘<< as “ andesine
Labradite as a “ labradorite
Anorthitite ‘“ if ** anorthite

By the addition of abundant and essential quartz to the
above ingredients we have appropriate names for the quartz-
granolites as follows: quartz-orthosite or granite in its restricted
use, quartz-andesinite, quartz-labradite, etc. In all the above
cases the quartz is an essential and not an accessory ingredient.
When accessory constituents are used in naming rocks the word

NOMENCLATURE OF FELDSPATHIC GRANOLITES lit

should, it seems to me, have the adjective form, as quartziferous
syenite for a syenite containing some quartz. If such a scheme
came into general use the term granite would still be a useful one
for nearly all quartz-feldspar rocks, in which sense it is used by

Michel Lévy and by many other geologists.
H. W. Turner.

DHE GROLOGY OF GE WEE SANDS Ora Niy
MEXICO

East of the San Andreas and Organ mountains of New Mex-
ico is an extensive valley that has been the subject of much dis-
cussion from the practical as well as the theoretical point of
view. The writer is not aware that any competent geologist
has had the opportunity to make an exhaustive study of its
unique features and ventures to put on record the results of a
somewhat careful if cursory examination of the valley and its
environs.

Our first visit was made by wagon from Socorro, the seat of
the county of the same name, by a route which afforded ample
opportunity to observe the varied geological conditions of the
region to the north and east. East of the Rio Grande, after
leaving the immediate valley of the river, the Tertiary red marls
are encountered, and lie in rather low terraces upon the foot of
the greatly disturbed red beds of Permian and Triassic age.
These beds are tilted and greatly faulted, leaving one in doubt
as to the sequence at this point, especially as there are curious
beds of fire clay and shale filled with a varied flora of carbonif-
erous habit consisting of numerous species of Lepidodendrids
as yet not worked out specifically.

The lower part of the Permian is composed of limestones
and sandstones capped by anhydride and gypsum beds, the for-
mer being in some places massive and upwards of fifty feet
thick. Extensive exposures of what is apparently carbonifer-
ous limestone constitute the principal axis of the low range at
this point, and are followed by the red beds over a large area on
the eastern side. These beds, as everywhere in the territory,
are impregnated with salt and saline alkalis as well as gypsum.
The springs are nearly always salty, and lower flats are covered
with “alkali.” Passing southward, in the immediate valley of
the Rio Grande, near San Antonio, is the remarkable basin of

I12

GEOLOGY OF THE WHITE SANDS OF NEW MEXICO 113

so-called tripoli described by the writer some years since.
There is no reason to alter the opinion then expressed that this
fine-grained scale-like deposit is the result of the attrition of
the floating pumice which forms the surface of the deposit. In
fact, in several other places in the Rio Grande valley similar beds
on a smaller scale have been encountered, and in each case the
material could be traced directly to the acid scoria of the
period of trachite eruption.

To the southeast we pass to the celebrated Carthage coal
belt, at which point a collection of Cretaceous fossils was made,
but, as they were not found in immediate connection with the
coal beds, it is impossible to decide what is the age of the coal
upon that basis alone. However, a little farther south in the
vicinity of Engle and East of the Caballo Mountains fossils of
the Laramie age seem to prove that the coal fields at this point
are of that period.

At San Marcial and at frequent intervals down the valley are
basaltic cones which have broken through the Tertiary gravels
and marls and supplied the material for the sheets of lava so
characteristic of the entire territory. It is easy to see that they
follow in a general way axes of weakness extending north and
south, but it is not so easy to determine the reason for a sudden
return to highly basic conditions after a gradual increase in
acidity in the volcanic flows of the territory. As the writer has
shown in several papers, the sequence is from an augite-andesite
or diabase through trachite and pitchstone and obsidian to rhy-
olite. The soda-syenite and phonolite may perhaps form a
transition from the andesite, though the occurrence of the soda
series is less general

It suggests itself to the writer that the serial arrangement
is to be attributed to an invasion of the silicious crust by the
internal heat, and that progressively less of the deeper material
was involved in these flows until it may be said that that chapter
of igneous activity was closed by the rhyolite eruptions. Long
after, perhaps as a result of the differential strain of glaciation
and its attendant shifting of the axes of rigidity of the crust,

114 C. L. HERRICK

deep crevices were formed entirely through the acid crust and
permitted a slow and relatively quiet overflow. This method of
eruption would account for a considerable degree of fluidity of
the lava and for the very slight surface disturbance. However
this may be, the flows of lava, usually of slight thickness, are
often of enormous extent, and where water has had access to
the loose materials beneath, the characteristic sal pats results.

Our way is now across the Jornado del Muerto, the perils of
passage being greatly reduced by the sinking of wells for
ranches at various places, though the terrors of a blizzard on
these barren treeless plains needs but to be experienced to be
appreciated. Though comparatively arid and seemingly barren,
the short grass furnishes a good subsistence to many herds of
both cattle and horses.

_ Rising by a rather moderate slope from the plain are the
foothills of the great range which begins with the Sandias east
of Albuquerque and is continued in a broken line by the Man-
zanos, the Oscuros, the San Andreas, and the Organs. In the
Sandias and Manzanos the granite, everywhere lying at the base
of the stratified rocks, so far as known, in the territory, is
exposed in an extensive escarpment on the east side of a very
important fault line and the superincumbent stratified rocks dip
rapidly to the east. In both the ranges mentioned the rock lying
upon the granite, or its gneissic or schistose equivalent, is a
quartzite whose materials seem not to have been derived from
the subjacent granite, but from a schist or quartz rock which we
suppose to have been the superficial portion of that series. The
age of the quartzite, as well as that of the granite, must at pres-
ent remain a matter of conjecture in spite of poorly preserved
fossils in the limestone layers found in one or two instances in
the midst of the granite. Reposing on the quartzite conformably
in the Sandia and Manzano ranges ts a silicious series with a few
limestone bands whose fossils seem to be of undoubted Coal
Measure age. This is followed by a dark conchoidal limestone
with shales having a fauna similar to that of the Upper Coal
Measures in Ohio as will be more particularly set forth in another

GEOLOGY OF THE WHITE SANDS OF NEW MEXICO 115

place. The lower series we have called the Sandia series from
the place where best seen. Some distance above the dark lime
is a sandstone or conglomerate which is rather inconstant in
thickness and may be absent, but which roughly marks the transi-
tion to the permo-carboniferous as generally developed in all
the ranges under consideration. This Coyote sandstone is partic-
ularly well seen in the canyon of that name in the south end of
the Sandias. Above this is the large series of massive gray and
silicious lime at whose base it is usual to find a large form of
Fusulina and, a little higher up, a well defined zone characterized
by the bryozoa preserved on the faces of the cleavage slabs.
Here begin the evidences of a transition to the Permian as indi-
cated by the presence of Mekella_ striatocostata, Terebratula
bovidens, Productus punctatus, and a variety of forms which are
mingled with fossils also found in the carboniferous below. At
the top of the gray lime is a large series of coarse, red quartzites
and sandstones interbedded with dark earthy limestones and
shales. There are few fossils except petrified wood and the few
found still preserve a carboniferous habitus. This Manzano
series is everywhere in evidence where a sufficiently high horizon
is reached but is often removed from the crests of the range
while it occurs in the eastern faulted extension. Following this
is the group of red quartzites, sandstones, shales, and marls which
we have recognized as the equivalent of the ‘‘red series’”’ of
Texas and Kansas. Three divisions can be made out in all parts
of the territory examined which have been named frem their
prevailing or characteristic color, though it is not to be supposed
that the color mentioned is constant. The lower or ‘red bed”’
division still retains some bands of limestone or lime breccias,
the latter being a very characteristic element. Some 500 feet
may be estimated as the average thickness of this division and
prior to the work recently done in the valley of the white sands
we had no definite evidence as to the age of the entire division.
We only knew that a narrow bed of quartzite near the base at a
point east of the Sandia Mountains contained the well-known Per-
mian forms such as Bekvellia parva, Myalina attenuata, Pleurophorus

s

116 Ge SES Se PIII OLS

subcuneatus, etc. The major portion of the series proved obsti-
nately barren. At the top of this division there are found
in the most widely distant parts of the territory enormous
deposits of gypsum and salt. In fact the presence of salines
may be said to characterize the series, but especially at the pas-
sage from the red into the chocolate beds above it. The choco-
late series has a thickness of at least 600 feet and passes through
quartzites and gray and red sandstone layers into the loose ver-
milion marls and clays of the upper division. So far, we have
no positive evidence as to the age of the two upper divisions, but
may presume the chocolate beds to be Triassic and the vermilion
division to represent whatever of Jurassic time is accounted for
in the territory or at least in the central portion.”

South of the Manzano range the continuity of the uplift is
broken so that in the Fra Cristobal and Caballo mountains near
the Rio Grande and in the Oscuro range farther east the dip is,
- as in the Sandias and Manzanos, to the east while in the San
Andreas, occupying an intermediate position farther south, the
dip is to the west so that the high escarpment with its granite
and schistose base faces the great salt plain.

In the interval between the range bordering the river and the
Oscuro Mountains we have abundant evidence of the existence
of the Cretaceous with its lignitic coals and it may be assumed
that the Cretaceous also extends southward on the west side of
the San Andreas, though nowhere exposed in the Jornardo del
Muerto. Passing eastward lower horizons gradually emerge till,
as we enter the interval between the north end of the Andreas
and the south end of the Oscuros, the red beds are seen in the
form of low hills with a dip to the east at the western foot of the
Oscuros. Underneath is a part of the Permo-carboniferous. It
appears, therefore, that the Oscuro range is separated by a fault
line from the axis of the Andreas. On the west side of the San
Andreas the red beds are represented as is shown by the exten-
sive deposits of calcium anhydride in the foothills.

‘It will be remembered that Professor Cope in 1875 identified part of this series
as Triassic and that Dr. Newberry described Triassic plants from New Mexico.

GEOLOGY OF TE WHITE SANDS OF NEW MEXICO 117

The eastern escarpment of the Andreas is bold and irregular
in the extreme but the fault which created it seems to have been
wavy so that a crenulated or sinuous aspect is presented to the
plain. The granite in some instances seems to have escaped in
pinnacled or columnar form and throws off the restraining influence
of the stratified rock to appear in jagged peaks. This is partic-
ularly true in the Organ Mountains where, however, there must
be added the influence of a later trachytic overflow. Our exam-
ination of the San Andreas was cursory but was sufficient to show
that the thickness of the stratified series is greater than in the
Sandias and Manzanos. The lower portion is composed of
quartzites and silicious shales which may be compared with the
quartzites in the Manzanos. Above this is a large series of gray
cherty limestones and quartzites of an entirely different texture
and appearance. This has baffled our search for fossils in the
Andreas and the Caballos where it is also well developed but,
fortunately, we have been able to discover in the upper part of
this series on the eastern side of the salt plain fossiliferous bands
which place the age beyond doubt. Spirifer Grimesi, Leptaena
rhomboidalis and other well-known Burlington brachiopods are
associated with crinoids of that period in great abundance.
Some of the bands are practically composed of the débris of the
crinoids.

Above the Burlington there seems to be a hiatus, for the
next species encountered are distinctively Coal Measure forms
and the sequence from this on to the top is as in the ranges
farther north though there seems to be a tendency for the lime-
stone to encroach on the sandy elements and for the individual
components to thicken toward the south, a fact which we inter-
pret as indicating deep-sea conditions.

Attention has elsewhere been called to the method of occur-
rence of the copper found so widely scattered through these
ranges. It was shown that the deposits of copper which have
attracted so much attention were formed in veins that extend
from top to bottom of the sedimentary series but do not seem to
cut the granite, at least to any depth or with any regularity.

118 (Ge I, SEI BL ICIM CIE

These veins are so regular that it is conceived that they may be
best explained as the result of warping or shrinking in the sedi-
mentary series and it seems certain that they have been filled
from above. The vein matter is chiefly calcite, fluor spar,
siderite and barite and it is chiefly at the intersection of the vein
with a band of iron-filled quartzite, reposing on the granite and
forming a definite selvedge to the sedimentary series, that the
copper is deposited. The ores include nearly all the common
copper compounds, calchocite, malachite, azurite, bournite and
cuprite predominating. Here, as in Hannover and Santa Rita,
it seems indubitable that the iron, accumulated by leaching, has
been the agent in precipitating the copper.

Between the Organ and San Andreas mountains there is an
area on either side where the granite is laid bare and it is true
that some show of copper may be found in crevices and basins
superficially on the granite. It is probable that all, or a great
part, of the copper of the two ranges has been originally
derived from the red-bed series (Permian and Triassic) by
infiltration, for the original existence of the cupriferous series on
top of the strata now remaining in the ranges is indubitable.
Dikes of diorite cutting through the granite and sedimentaries
along or near the fault line have caused portions of the latter to
lie in irregular fragments along the foot of the escarpment to the
east, the strata dipping towards the dike which served to pry
them from their original position.

Standing upon a jutting eminence of the San Andreas and
turning eastward one looks out upon a scene difficult to parallel.

At one’s feet 1s an enormous plain, apparently as level as a floor,.

over forty miles wide and extending as far as eye can reach to
north and south. On the southern horizon rise the Jarillas
Mountains which only partially interrupt the plain, while to the
northeast are the snow-capped peaks of the Sierra Blanca.
Northward the plain is narrowed by the eastward intrusion of
the Oscuro range while it is possible to make out the dark area
of basalt which covers that part of the plain to the east and south-
east of that range. This is the widely-know ‘‘mal pais” of

a —eEeEeeEEEeeEeEeEeEeEeEeEeEeeeeeee

GEOLOGY OF THE WHITE SANDS OF NEW MEXICO 119

Socorro county which has proven such an effectual barrier to
communication between the Rio Grande valley and the growing
region of White Oaks. South of the ma/ pais is a great white
sea on which one can fancy the glint of white-caps. Sucha
body of water being out of the question the uninstructed observer
would surely think himself the victim of a mirage but we
recognize in the snowy area the tamous white sands. Curious
and conflicting stories are current respecting the area but the
truth is not less interesting. We had already been forced to the
conclusion that the true origin of the saline and gypsum beds is
to be sought in the red series above mentioned. It seemed at
first, however, that the geological relations would prove baffling.

Rising abruptly from the level plain on its eastern side are the
foothills of the Sacramento range near which pass the trains
upon the newly-finished El Paso and Northeastern railway.
The escarpment is nearly perpendicular and the dip is very
slight and to the east. The bottom of the sedimentary series is
not reached, at least in this vicinity, but it is evident from a
comparison of this with the western escarpment that the base
is not far distant. The section is given in detail below but we
were very fortunate in coming upon a locality where the lower
portion of the section is fossiliferous About 560 feet from the
base, at Dog Canyon, some 12 miles southeast of Alamogordo isa .
band of crinoidal limestone which, together with the gray lime
and quartzite above it, contains numerous, though poorly pre-
served fossils. Among these enough forms were identified to
determine the limestone as Burlington. As nearly as we could
determine the Burlington is represented by at least 250 feet.
Several intercallary sheets of igneous rock (diorite, with por-
phyritic hornblende) penetrate the strata and obviously connect
with a boss farther east and higher upthe canyon. The influence
of the intrusive may account for the amount of chert seggre-
gated in this portion of the section but, for whatever cause, the
limes are chiefly highly silicious and quartzite has replaced
former limestones. Above the Burlington, which is entirely
absent farther north, is the entire series of Coal Measure

120 CES ETET KL ORS

limestone and sandstone as seen in the Sandia range except that
the deeper sea conditions have expressed themselves in greater
thickness of limestone. The fossils in the lower part are of
mid-carboniferous types but pass somewhat gradually into the
assemblage which we have characterized as Permo-carboniferous.
Meekela, Terebratula bovidens, Productus punctatus, a large Belle-
vophon and many other familiar forms indicate an approach to
the top. Above the measured escarpment but inaccessible to
our reach is a series of what appear to be yellowish sandstones
or quartzites which may confidently be referred to the Manzano
series at the top of the Permo-carboniferous. Northward the
dip rapidly veers to the northeast and thus the several horizons
drop below the surface and bring still higher ones than those
seen at Dog Canyon within reach. About 16 or 18 miles west of
the main escarpment is a low ridge of hills which prove to

consist of carboniferous limestone but bearing evidence on their .

western aspect of the fault which brought the plain down to a
lower level. This ridge is most instructive in showing that the
fault was not a single break but by steps or successive faults.
Wells in the plain to the west all show the existence of the red
beds both by the presence of salt (often strong brine), but also
by the red color of the marl brought to the surface. North of
the outlyer spoken of is a most interesting spring which has
built up for itself, geyser-like, a mound of some thirty feet
above the general level from which issues a quantity of warm
and highly saline water which flows into a depression and, sink-
ing from view, leaves a large salt and alkali flat. Other similar
lakes are grouped in the neighborhood. The actual character
of the deposit is generally masked by a calcareous marl of white
or gray color which forms a crust over the entire plain and is
highly charged with salts except at the immediate surface.

But passing northward and observing several other saline
springs similar to the one described, the route carries us through
the intensely modern ‘‘boom” town of Alamagordo with its
great sawmills fed from the Sacramento Mountains by a spur
railroad and the equally typical old Mexican town of Tularosa

GEOLOGY OF THE WHITE SANDS OF NEW MEXICO 121

where nearly every house is of adobe. The intense red color of
the adobe awakened our curiosity and led us to the examination of
the escarpment to the east and north. As we hoped, the dip
had sufficed to bring to the general level strata which at Dog
Canyon were out of reach and the lower third of the red series
with its capping of gypsum and salines is at the foot of the sec-
tion. The following is the section as casually examined during
our visit —a section which will yield a large suite of interesting
fossils of decided Permian facies, though well-known carboniter-
ous forms extend throughout. Commencing at the bottom, we
have first a poorly exposed series of silicious shales and thin-
bedded limestones in which is a characteristic Permian assem-
blage including Myalina permiana, Myalina attenuata, Pseudomonotis
hawnt, Aviculopecten occidentalis, etc.

Then follow, as we ascend:

Reddish shales and loose sands - - - - - - T5eteet
Limestone - - - - - - - - - - sai Oey
Greenish sandy shale : - - - - - - = Io feet
Coarse conglomerate with pebbles of granite, etc. - - 15 KO) Tito
Purple red sand with pebbles’ - - - - - - ZOMOR25 ita
Earthy limestone - - - - - - aaa re - Be i
Loose red sand - - - - - - - - - Hite) 8
Coarse red conglomerate - = = = - = = Ato) Go
Red sandstone - - - = - - - - - Ons
Loose red sand and shales -_ .- - - - - - er iilts), 6
Conglomerate - - - - - - - - . - Asics
Limestone - - - - - - - - . = =p De 4 es
Greenish sand~ - - - - - - - - - SHel2s a
Earthy lime shales and sand - - - - - - SEL Pe
Limestone and calcareous shale - - = - - - - One
Sandy shale and green sands - - - - - - 25 tO AO
Well marked bench of gray lime - - - - - = Sruis
Red shale including a very irregular conglomerate - - 5) abso) == 58
Thin bed of lime - - - - - - - . - 1 foot
Green fissile shale - - - - - - - - . - 6 feet
(Gypsiferous marl, probably surface deposit) ; - - = i OOnmes
Limestone and shale with numerous small fossils —- - = Migs
Brown or red shale with numerous fossils —- - - - Sere See

Sandstone - = : = 2 2 Ls E 2 es or ee

122 Oo Log JaMBISIEM CIE

Shale - - - - - - - . - - - 6 feet
Sandstone - - : : = = : - - 592-8 ((®)
Limestone - - - - - - - = - - - I foot
Green sandstone with calcareous band - - - - - 20 feet
Calecareous zone - - - - ; = ; - - - O
White sandstone - : - - - - - - - Si iesAlomss
Shell limestone fossils - - - - = : - - I foot
Nodular marl - - - - - Sept & - - 15 feet
Nodular limestone - - - - - - - Binet

Our ascent ended here but oe, appeared the gypsum beds
reposing upon red and white marls as in the Nacimiento region
and elsewhere. Still above and forming separate terraces are
the chocolate and vermilion beds, and at the top of the section
the lower Cretaceous. The creeks or arroyos which traverse the
gypsiferous horizon come laden. with salt which is epostsed | as
a white coating upon their beds and banks.

Having satisfied ourselves both as to the age and the charac-
ter of the deposits which underlie the great plain, we undertook
a study of the plains themselves. At the southern end of the mal
pais which forms the northern boundary of our field of work,
numerous springs gush out from beneath the thin sheet of black
basalt. These springs differ from those from the salt valley
itself, in that the water is not warm nor appreciably salty. It is
apparent that the lava has served to retain the water which, on
making its way beneath the sheet, has excavated channels in
which the water may be heard rushing by one crossing the lava.
One of these streams in particular, at Mal Pais spring, forms a
considerable creek which supports a varied plant and animal life
including fish of considerable size and several crustaceans (Gam-
marus or the like). The water, before it flows many rods,
becomes distinctly salty and bitter. Ata little distance to the
south begins an area of depression which is forty miles long and
receives the drainage from all directions. This whole area is
covered with saline efflorescence while all the shallows, when dry,
as they are most of the year, have considerable deposits of salt
on the surface and the subsoil or under clays are infiltrated with
alkaline salts the nature of which will be fully discussed in
another place

—— GQ. ee ——————————————eeerereorrreaeee_r |

GEOLOGY OF THE WHITE SANDS OF NEW MEXICO 123

About one mile from the Mal Pais spring above mentioned
is a small salt lake which has furnished the salt for ranches for
a radius of many miles during the historic period and at our visit
the surface was covered to the depth of an inch or so with pure
crystalline chloride of sodium. Still west and forming the west-
ern limit of the visible saline beds, is a drainage arroyo whose
source seems to be in the red beds that emerge west of the Oscuro
Mountains and conveys their saline water to the basin of the
sands. Along the course of this arroyo are numerous salinas
and alkali flats and these gradually broaden to form what may
be described as one vast alkali and salt plain where brine stands
for part of the year. Other arroyos come in from the west in
some of which, even at the time of our visit, was a considerable
quantity of flowing water which is a strong brine unfit for cattle
even when accustomed to drink from the saline springs which
unwonted animals will reject. Where these arroyos enter the
salt lake and along the shores of the lake are bluffs of erosion
some of which are over twenty feet high. In these exposures we
encounter the red bed formation with its marls and gypsum
deposits. Large quantities of pure crystalline gypsum are here
exposed and the marls are alkaline and saline. We have there-
fore local proof, as well as the most conclusive evidence from
the environs, that the whole of the plain is in or near the horizon
of gypsum and salt that separates the lower from the middle
member of the red or saline series.

In the salt flats the ribs of gypsum rise in successive ridges, and
the action of the elements soon breaks up the exposed crystals
into small grains which are carried by the winds hither and yon.
This characteristic of the salinas accounts for the most curious
and notable of the many peculiarities of these plains, namely the
white sands. These have been attributed to the action of springs
and the material has been supposed to have crystallized. from
solution. It has been suggested that the sands have been col-
lected by floods, but a short examination shows that these great
drifts are simply sand dunes collected from the gypsum sand
formed as above stated on the surfaces of the lakes. The salt

ee

124 Gy Uh, SEWEIRIRM ETE

and alkaline salts are also driven with the gypsum but on account
of their solubility they do not remain in the dunes. These dunes
lie to the south and east of the flats whither they are driven by
the prevailing winds and not only cover a large part of the
salinas themselves, but form.a growing fringe to the east and
south. The dunes are, in the majority of instances, very pure
gypsum though there is a small commingling of earthy impurities.
The soil underneath is impregnated with salt and soda and salt
lakes are scattered over the area covered by the dunes. The
intervals between the crests of the ridges support a scanty but
very interesting vegetation. Near the southeastern angle of the
sands is a very important salt lake which has been known as a
source of salt for the ranches for many years. The north and
south extent of the ‘‘white sands”’ is about 35 miles while
the greatest breadth at the southern margin is about 18 miles.
The lines connecting the extreme points are irregular, enclosing
roughly a triangle of about 350 square miles. To this may be
added nearly as much more of saline land on the west and in
isolated areas to the south. The whole plain is geologically of
the same nature, but, inasmuch as it is either higher than the
basin or is more completely drained (to the south), the saline
ingredients are not brought to the surface.

East of the Jarillas Mountains this plain again gives external
evidence of its subterranean supply of salines while far to the
north, beyond the covering of lava, there are depressions of the
same character and of the same geological age and nature. The
fact that such depressions occur in New Mexico only in connec-
tion with the red beds leads to a suggestion that may be worthy
of consideration. It is evident to anyone who has studied the
geology and geography of the territory that it is, as Major
Powell said long ago, the best drained region in the world. The
comparative newness and permeableness of its strata all militate
against the formation of local basins. There has been no glacia-
tion to produce local lake reservoirs. Erosion has kept well in
advance of secular changes of level and barriers of local origin
do not prove capable of retaining the waters which come in

GEOLOGY OF THE WHITE SANDS OF NEW MEXICO 125

torrential plentitude when they come at all. Some explanation
must be sought for the basins found in the saline areas. It
might be supposed that such explanation would be found in the
depressions resulting from the post-Tertiary lava flows which
occur over the entire territory. To this it may be replied that
the basalt is certainly of deep origin, for the preceding flows
were all acid and the basalt overflows are essentially similar
among themselves and demand a common origin at a depth.
Moreover the distribution of the flows indicates that the oro-
graphic lines of weakness opened were of almost continental extent.
The depressions due to the outflow of basalt would not account
for the local basins referred to and we are driven to the conclu-
sion that these slight depressions are due to the effect of the
removal of the soluble ingredients in these beds themselves.

The discussion of the economic aspects of these beds will
occur in the forthcoming bulletin of the University Geological
Survey of New Mexico.

Cee AERRICK.

IDNESCIRIUPINOIN| OM IWATE)
PLATE I.

Sketch map of the region of the “ White Sands” including part of Dona
Ana, Socorro, and Otero counties, New Mexico.

PLATE U1,

Mostly Permian fossils from exposures near Tularosa and east of the
Sandia Mountains in Bernalillo county. These plates are given to illustrate
the fauna rather than as a basis for a discussion of the species figured, which
have as yet been subjected to no critical study.

Fic. 1 Pseudomonotis n. sp. (costatus).

Fic. 2. Bellerophon sp.

Fic. 3. Aviculopecten cf. coxanus.
Fic. 4. Pseudomonotis radialis Meek.
Fic. 5. Undetermined.

Fig. 6. Undetermined.

Fics. 7, 8. Rhynchonella osagensis Swallow. Two views.

Fic. 9. Pleurotomaria cf. subdecussata Geinitz.

Fic. 10. Pleurotomaria marcoutana Geinitz.

Fig. 11. Rhynchonella sp. Two views. (cf. R. osagensis Swallow).

126 (ON So JEP ETA RM CTE

Fig. 12. Terebratula ? sp. Two views.

Fic. 13. Zaphrentis sp.

Fig. 14. Productus cora D’Orb.

Fic. 15. Portion of the whorl of Awomphalus sp.? All the above are
from shale number III of the Tularosa section.

Fig. 16. Bakevellia parva Meek and Hayden. From base of section
near adobe smelter east of Sandia Mountains at the base of the Permian.

Fies. 17, 18, 19. Undetermined gasteropods from the base of the Tula-
rosa section.

F1G. 20. Orthoceras sp. Base of Tularosa section.

Fic. 20 dzs. (Lower left corner) Edmondia sp. Same place as the above.

FIGS. 21, 22, 23. Weekella striatocostata Cox. From No. 3, Tularosa
section.

Fic. 24. Myalina permiana, base of Tularosa section.

Fic. 25. Bellerophon montfortiants Norwood and Pratten. Base of sec-
tion at adobe smelter.

Figs. 26,27. Pleurophorus subcuneatus Meek and Hayden. Same as the
above.

Fic. 28. Sedgwikia topekaensts Shum. Shales below upper layers at
Tularosa.

PLATE III.

Fig. 1. Aviculopecten occidentalis Shum. Left valve.

Fic. 2. Aviculopecten occidentalis Shum. Right valve.

Fic. 3. Psewdomonotis hawnt Meek and Hayden. This and the above
from the lowest level of the Tularosa section.

Fic. 4. Myalina perattenuata Meek and Hayden. Adobe smelter east
of Sandias.

Fic. 5. Wyalina swallovi Shum. Upper Carboniferous, Sandia Moun-
tains.

Fic. 6. Discina convexa Shumard. As above.

Fic. 7. Gervillia longa Geinitz. As above.

Fic. 8. Chonetes granulifera Owen. As above.

Fics. 9, to. Unidentified gasteropod. As above.

Fig. 11. Myalna ? Permo-Carboniferous east side of Sandia Mountains.

Fic. 12. Edmondia sp. Base of Permian, adobe smelter.

Fic. 13. Ldmondia aspinwalensts Meek. Permo-Carboniferous. Jemez
Spring.

Fic. 14. Unidentified gasteropod. Upper Carboniferous.

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GEOLOGY OF THE WHITE SANDS OF NEW MEXICO 127

Jour. GEOL., VoL. VIII, No. 2 Plate II

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Jour. GEOL., VoL. VIII, No. 2 Plate III

LTE TORIGINFOR NITRATES IN CAVERN EARTHS

Mucu interest has been taken in the great caverns of Vir-
ginia, Kentucky, and Indiana by tourists, and considerable
popular literature has been published, especially in description
of Mammoth, Luray, and Wyandot caves. In this literature
rather frequent allusion is made to the ‘“‘nitrates’”’ in cavern
earths, and occasionally a theory is advanced to explain their
origin. Popular interest is awakened in this question by the large
amount of ‘‘saltpeter” known to have been taken from Mam-
moth Cave during the war of 1812, and from similar caverns in
Alabama and Georgia during the Civil War for the manufacture
of gunpowder.

The origin of this supply of nitrates is commonly ascribed to
animal remains, and especially to the excrement of bats. In
Mammoth Cave, however, the cavern earth was worked for
nitrate for a distance of over five miles from the only open-
ing known which leads to the surface, while bats as a rule
go but a short distance from the entrance of the cavern. Again,
on account of the antiseptic character of the atmosphere of
caves, we would expect, in case the nitrate was derived from
bats, to find some animal remains, in the form of their dried
bodies, their bones, or their excrement; but organic matter of
any kind is rare in cavern earths. The hypothesis ascribing
such an origin to the vast stores of nitrates taken from Mam-
moth and other caverns seems, therefore, inadequate.

Caves in limestone regions are due to the solvent action of
water containing carbon dioxide. This process must have been
very slow and in most cases unaided by mechanical erosion, thus
leaving the insoluble portion of the limestone as a deposit on
the floor of the cavern. This residue is known as cavern
earth.

From the mode of formation of caves, it is evident that this
residue must have been washed perfectly free from all salts.

129

130 WILLIAM HT. HESS

readily soluble in water by the water which slowly carried away
the limestone itself during the formation of the cavern.

Recent progress in bacteriology and agricultural chemistry
has thrown much light upon the origin of nitrates in soils by
the oxidation of organic matter in the presence of certain bacteria.
The surface soil in cavernous regions is usually loose and porous,
and consequently favorable both for nitrification of organic nitro-
gen and for downward percolation of the surface water. It may
not be unnatural, then, to ask whether the nitrates in cavern earths
may not have orginated wholly or in part from nitrification of
organic matter at the surface and the subsequent leaching of the
nitrates so formed into the caverns. Caves would thereby act
merely as receptacles for the surface drainage, and provide an
avenue for the return of the percolating water to the atmos-
phere by evaporation. If the nitrates in caves originated in this
way, we would expect to find also in cavern earths such other
soluble constituents of soils as must necessarily have been
leached out along with the nitrates.

By leaching cavern earths with cold water some material is
always extracted. The amount thus washed out is sometimes
-as much as 13 per cent.of the sample. The following analyses

are given of the soluble matter of cavern earths derived by ~

washing the samples with cold water, the figures representing

percentages s

oxide anhydride

Source Calcium Sulphuric Alkalis | Chlorine Nitric acid | Ammonia
|
|

Mammoth Cave, Ky. 1.06 2a 1.45 0.28 Oo 37 0.005
Mammoth Cave, Ky. 2520 4.57 3.04 ie dll 1.36 0.001
Saltpeter Cave, Ind. Ds Bit 32.30 2.26 0.23 1.88 0.007

From these results it is seem that nitrates form only a small
portion of the total soluble material in cavern earths.

A kilo of subsoil over Mammoth Cave was placed in a per-
colator, and two liters of water charged with carbon-dioxide
were added and allowed to stand for a week, with frequent stir-
rings, when the water was slowly drawn off. The water was then

ORIGIN OF NITRATES IN CAVERN EARTHS 131

evaporated in a platinum dish and the residue was analyzed. A
sample of cave earth collected as nearly as possible beneath the
spot where the sample of subsoil was taken, was also treated in
the same way. A sample of bat guano and one of the earth
occurring just below the guano were subjected to the same
treatment. The results of these several analyses are given in
the following table, the figures representing percentages of the
sample taken:

Mammoth. Cave Dixon’s Cave
Subsoil over Cave earth Earth below

Mammoth Cave below at (gLeine bat guano
Sulphunteacidsts Oomacem ac 0.0054 4.16 0.67 0.031
Wimess Ca@ ion cgerepeetessicees 0.0018 2.03 3.34 0.23
Alkalis, Na,O, and K,O... 0.00288 2.86 0.37 0.26
Phosphoric acid, P,O;..... trace 0.0003 0.044 0.0137
Jmmnvorneys INalas sogaso se 8e 0.00192 0.011 0.102 0.019
INGE NCIS INGO Ga gaa boc6 0.0068 0.82 6.016 0.0118

By comparing these analyses it is evident that the soluble
material in the cave earths might have been leached from the
soil above.

The bat guano forms a thin layer over the floor of Dixon’s
Cave, and is composed of a mixture of excrement and fuzzy
material from the bats’ bodies, together with sand and earthy
matter from the walls of the cavern. Judging from the above
analyses, this layer seems to have acted as an excellent absorb-
ent preventing the further percolation downward of material
dissolved from the soil above the cave, since the earth below con-
tains very little soluble material.

But guano was found to contain considerable amounts of
salts of phosphoric acid soluble in cold water, while the cavern
earths proper contain only traces of these salts. The total per-
centage of phosphate dissolved out of bat guano by dilute acid
was found to be about the same as that derived from cave earth
by the same treatment. The following results of analyses of bat
guano, taken just as it came from the cave, making no attempt
to mechanically separate the sand and earthy matters, and of cave

137 WILLIAM H. HESS

earth, both from Dixon’s Cave, were obtained by igniting the
dried samples and then treating them with dilute hydrochloric

acid.
Bat guano Cave earth
Loss on ignition . - - ; 2° Bo 1(6) 6.02
Insoluble residue - = - - - 40.65 73.80
Soluble silica, SiO, = - - - - - 1.03 trace
Calcium oxide, CaO - - - - 10.95 7.51
Ferric oxide, Fe,03 - - - - = G20 B27)
Alumina, Al,O3;_~ - - : - - 5o27/ 2.41
Magnesia, MgO - - - - hl Oneyy/ 0.30
Sulphuric anhydride, SO; - - - 4.37 Dpy
Phosphoric anhydride, P,O; - - - 2.62 2.10
Alkalis and loss” - - = - - 2.38 69/2

This sample of cave earth contained no perceptible organic
matter.

It seems from a comparison of these analyses that we cannot
prove the presence of animal remains by the total content of
phosphoric acid soluble in dilute mineral acids, since a residue
from limestone must contain considerable calcium phosphate on
account of the insolubility in water of this salt of calcium.

Analyses of the water dripping from the roofs of caves were
made, and results were obtained which do not vary markedly
from results obtained from analyses of ordinary sub-drainage
waters. The following is an analysis of the residue from water
which dripped from the roof of Mammoth Cave:

Milligrams per liter

Silica, SiO, - - - - - - = 1923
Sulphuric Anhydride, SO; : - > 15.81
Phosphoric Anhydride, P.O; - - = ALLAGE
Chlorine - - - : - - - Doli
Ferrous Carbonate, FeCo; - - - - 1.02
Calcium Carbonate, CaCO; - - - 53-61
Magnesium Carbonate, MgCO;_~ - - a ely
Alkalis, Na,O and K,O - - - 16.56
Ammonia, NH; - - - - - SOLO!
Nitric Acid Anhydride, N,0O, - - - 5.71

A comparison of the soluble constituents given in this analy-
sis with the soluble material extracted from the cave earth, as

ORIGIN OF NITRATES IN CAVERN EARTHS 133

shown in the preceding analyses, points forcibly to the probable
origin of these salts in cavern earths.

It was found from analyses of many samples taken from
Saltpeter Cave, Indiana, so as to cover practically the whole floor
of the cavern from the opening to the end, that nitrates were
distributed throughout the entire extent of the dry chamber,
irrespective of distance from the entrance. Since bats do not
go far inward from the entrance of caves, and since we find no
organic matter in cave earth to indicate an animal origin for the
nitrate contained therein, it is evident that we cannot regard the
nitrates in cavern earths as originating from bat guano.

The conclusion reached from this investigation is that the
nitrates in caves were brought in by water percolating through
the soils above the caves and were deposited on the floors. Cur-
rents of air in and out of the caverns removed the water, and the
various salts it previously held in solution were left as an inherit-
ance to the cave earth. A cavern acts, therefore, merely as a
receptacle for stopping a portion of the surface drainage. This
accumulation of salts occurs only in caverns where the inflow of
surface water does not exceed in amount the water removed by
evaporation. In wet caves the soluble salts are washed onward
with the water bearing them and so are not deposited.

Nitrates found under overhanging cliffs are of a, similar
origin. Water bearing dissolved nitrates percolates through the
soil and finally oozes out at the surface. The water evaporates
and leaves behind an incrustation of its soluble materials. The
nitrates thus formed under overhanging cliffs remained perma-
nently stored there, being securely protected from rain. They
served, along with the nitrates found in the caves of Alabama
and Georgia, as a source of saltpeter used by the South during
the Civil War for the manufacture of gunpowder.

When vegetable matter is piled up and allowed to decay, an
incrustation of potassium nitrate forms on the surface. The
vegetable or organic nitrogen has been oxidized to nitric acid.
The nitric acid combines with the potash of the plant to form
potassium nitrate. The water evaporates from the pile and

134 WILLIAM H. HESS

leaves its load of nitrate behind as an incrustation on the sur-
face, while water from the interior of the pile works gradually
towards the surface to take the place of the water removed by
evaporation. Thus the materials soluble in water are slowly
brought to the surface and left as a deposit which may be
removed mechanically. This is an old method of obtaining
saltpeter from manure heaps, and it is even now used to a small
extent in Burope, siihey occurence) of the smitrates; imecayesmas
an incrustation on the surface of the cavern earth shows that
water has been removed by evaporation in much the same way
as from the overhanging cliff and from the compost heap.

We always have nitrogenous matter scattered over the sur-
face of the soil and this decaying vegetation furnishes contin-
uously during .its decay a small amount of nitric acid. All
nitrates are soluble in water and so are sure to be found in the
percolating water. If, then, the percolating water is intercepted
and evaporated, the nitrate must be left behind. Nitrates should,
therefore, occur in all caves and analyses of the cavern earths of
a great number of caves in Indiana and Kentucky demonstrates
that the occurrence of nitrates in cavern earths is general. No dry
cavern earth was found which did not contain soluble salts of
nitric acid, and these salts were distributed uniformly from the

entrance to the end of the cavern.
WituiaMm H. HEss.

February 23, 1900.

THE CALCAREOUS CONCRETIONS OF KETTLE
POINT, LAMBTON COUNTY, ONTARIO

Ir cannot be said that the mechanics of the concretionary
process in sedimentary rocks is well understood. The well-
known spherical concretions of Kettle Point, at the southern end
of Lake Huron, appear to throw some light on the problem of
the mise en place of thoroughly exotic material, aggregated
by this slowly acting molecular attraction. The purpose of the
present paper is to illustrate the mode OLPOGCcUnLENce and ato
indicate some facts leading toward the interpretation of these
singular bodies.

Logan has given us a concise description of the conditions
at Kettle Point in the Geology of Canada, published in 1863."
Reference is also made to them by Rominger;? but in neither
case was actual illustration employed nor description given of
perhaps the most remarkable characteristic of the concretions.

About one half mile eastward of Kettle Point the highway
from the town of Thedford decends sharply on a remarkably well
preserved sea cliff of the formerly expanded Lake Huron, to
the level of a gently sloping bench, cut in part in the drift, in
part in the shales which underlie all this portion of Lambton
county. At the Point itself the shales are seen to be wasting
very rapidly on the face of a modern cliff from six to fourteen
feet high and a few hundreds of yards in length. This condition
is highly favorable to the exposure of the concretions, and one
could hardly ask for more ideal sections for the study of struc-
tural details in the bed rock.

According to Logan these beds represent the equivalent of
the Genesee Shale in New York state, which bears concretions
of the same nature as those under consideration. Rominger

tPp. 387, 388.

2 Rep. Geol. Sur. Michigan, Vol. III, 1873-1876, p. 67.

3Cf. HALL, Geology, Pt. IV, in the Nat. Hist. of New York, pp. 220 and 230.

135

136 REGINALD A. DALY

put them in his ‘‘ Black Shale” division of Michigan,* which C.
Ey Wright has called the St. Clair Group.) ihe widemextent
of these shales is further emphasized by their correlation with
the important zone of the ‘“‘Huron Shale”’ in Ohio.3

At the Ontario locality the rock is argillaceous throughout,
of a dark ‘brownish-gray to black color, which is partly due to

Fic. 1. General view of the shale at Kettle Point, showing jointing. Several
‘concretions appear above the surface of the water.

the strong impregnation of bituminous matter, so abundant as to
make the rock inflammable. Fossils are not rare; indeed, there
is a very striking exhibition of large specimens of Calamites
enornatus, and of other plants, lying prostrate in the shale. In
addition to the calcareous concretions there is a great abundance
of concretions of iron pyrites, which are, however, always small,
generally lenticular, with the greatest diameter under three

“(Ojob Cling [Do Ofc

2 Rep. Geol. Sur. Michigan, Vol. V, 1881-1893, Pt. II, p. 21 (ed. by Lane).

3 NEWBERRY, Geology of Ohio, Vol. I, 1873, p. 154.

CALCAREOUS CONCRETIONS OF KETTLE POINT 137

inches. The decomposition of the pyrites has led to the efflo-
rescence of the usual sulphates of iron and alumina and of the
hydrous oxalate of iron, humboldtite.

The shale is nearly horizontal, well laminated and very fissile,
the flakes of the rock being readily split out and piled up on
edge by the waves, which thus build a curious belt of jagged and

Fic. 2. Concretion and deformation of the shale.

shattered fragments on the bed rock. The only other notable
structure in the interconcretionary spaces is the universal occur-
rence of two extremely perfect systems of vertical joints at right
angles to each other (Fig. 1). These joints affect the shale
only, and do not pass through the concretions anywhere, so far
as I have had opportunity of observing the latter.

The most striking structure in the shales is, however, the
local departure from the normal horizontal position of the parts
of the beds in the immediate vicinity of the concretions. In
every one of the dozen well-exposed concretions still in place
the strata are plainly arched over the upper hemisphere and bend

138 Vil BCI INAVEIO) Val, JOVAIE YZ

under the lower, and show clearly the effect of deformation
along the radii of the equator. In fact, the impression is at
once given the observer that centrifugal force of nearly equal
amount has been exerted along all radii of each sphere (Figs. 2,
3,and 5). A similar disturbance of the usual, nearly horizontal,
attitude of the beds of this formation has been noted by New-

Fic. 3. Deformation of the shale about a medium-sized concretion.

berry at Worthington, Franklin county, Ohio, and by Rominger
in the “Black Shale” of Michigan.’

The concretions themselves are composed essentially of
crystallized carbonate of lime, the crystals arranged radially and
always in direct contact with one another. There is practically
no argillaceous material in them, and in no observed case does
the stratification of the country-rock run through the concretion,
The shape is usually that of the almost perfect sphere (Fig. 4),
though often this form is somewhat lost by the slight flattening

t Geology of Ohio, Vol. I, 1873, p. 155.
2Op. cit., p. 66.

CALCAREOUS GONCKEMONS OF KHTTLE POINT 139

of the concretion along the diameter perpendicular to the plane
of stratification of the shale. True spheres and spheroids
exhaust the list of observed forms. The average diameter is
nearly two feet ; the largest specimen now well exposed on the
shore, a spheroid, has a polar diameter of a little more than
three feet, an equatorial diameter of about three feet six inches

Fic. 4. General view of partially exposed concretions.

(Fig. 5); the smallest specimen may measure about one foot in
diameter.

Large numbers of the concretions are being washed out of
the much less resistant shales by the waves; their freeing from
the matrix may be seen in all its stages (Fig. 4). But the
number now remaining on the shore does not represent the total
that could be counted were it not for the deplorable habit of the
numerous visitors to the Point, who not only carry away the
heavy specimens bodily, but break up others with the hope,
destined to disappointment, of finding something at the core more

140 REGINALD A. DALY

interesting than the interior of the already shattered ‘‘kettles.”’
It is said that the concretions may be seen on the bottom -
in the very shallow water of the lake five or six miles from
Kettle Point, and that specimens may be readily fished from the
bottom as much as two miles from the shore, where they have
been leached out by the erosive action of the larger waves.

Fic. 5. Large concretion in place; the shale in its immediate vicinity exhibits
slaty cleavage developed tangentially to the concretion.

Composing as they do such a comparatively large proportion of
the rock, and occurring in similar profusion in the Upper Devonian
of Michigan and Ohio, it is hardly just to say, in the words of
Dana, that radial spherical concretions are ‘‘ of inferior geological
importance.*

A chemical analysis of one of the darker tinted brown con-
cretions was made, and yielded the following percentage com.
position :

*Manual of Geology, 4th ed., p. 97.

CALCAREOUS CONCRETIONS OF KETTLE POINT 141

CaCO; /- - - - - - - - - 88.42%
MgCO; 5 : e : = = = = 2.99
Fe,03 - - - - - - - - = O97
Residue insoluble in HCl] (SiO,) - - - - 4.25
Hydrocarbons (and H,O) - - : z Ei) 323
99.60

Fic. 6. Looking down on the concretion of Fig. 5; fractured surface shows con-
centric structure, the radial arrangement of the crystals not conspicuous in the photo-
graph.

The powder from which this analysis was made was previ-
ously dried at ordinary temperatures in a desiccator ; any residual
water was driven off at the low heat used to expel the hydro-
carbons. The latter cannot then be said to have been exactly
determined, but they probably do not total less than 3 per cent.
The shales round about were found by Hunt to contain 12.4 per
cent. of volatile matter, presumably hydrocarbons.’ The appear-
ance of the magnesian carbonate is to be correlated with the

* Chemical and Geological Essays, p. 179.

J 42 REGINALD A. DALY

observation by Garwood that some of this substance must be
present if a limestone concretion is to grow large, although his
analyses show that more than 30 per cent. of that carbonate
seems to prevent the concretionary process.!

In all cases the structure is typically radial throughout the
concretion, except at the rather indefinite small core of massive
crystallized lime carbonate, which can usually be seen at the
center. I have found no organic center of concretion, and no
center other than calcite in any specimen. The free ends of the
radiating crystals present the characteristic cleavage-planes of
calcite, and the curved surface of the sphere is otherwise indented
only by the faint depressions where the latter was in contact with
the layers of shale (Fig. 5). Lastly, there is often to be seen,
in addition to the radial structure, a concentric banding in the
_ split-open sphere, a layering that seems to be original and con-
nected with varying conditions of growth (Fig. 6).

The most important problem in connection with these con-
cretions doubtless adheres to the question as to how the strata
came to be deformed on all sides of each spheroid. That very
considerable mechanical energy has been expended in the process
is evident, not only in the development of a dome over the upper
hemisphere and of a cup holding the lower hemisphere, but also
in that of a sort of slaty cleavage, which can sometimes be ‘dis-
cerned in the shale adjacent to the equatorial zone (Fig. 5).
What is the source of the energy?

One of the first explanations that suggested themselves to
me consisted in referring the deformation of the beds to differ-
ential movements in the strata as these adjusted themselves
to the loss of water, and to the ensuing consolidation of the orig-
inal muds to shale. The concretion itself would not lose bulk in
such a case, and the layers overlying would be supported at the
upper pole of the spheroid, while there would be less and less of
such support for the same strata along lines radiating from the
pole in the horizontal plane, until a maximum of instability would
be reached outside of the equatorial circle. Here there would

tGeol. Mag., 1891, p. 439.

CALCAREOUS GONGCRETLON S| OF GELTELE iP OLND, 4VA3

be a maximum of collapse which means, in the end, a doming
above the upper hemisphere. I have found that the same
explanation had been brought forward by both Newberry’ and
by Rominger.? But it leaves out of account the structural cup,
which holds the lower hemisphere, and which is just as well
developed as the dome overhead (Fig. 3). Moreover, the exist-
ence of the concretion before the act of consolidation is not
considered; yet we must believe that a theory of the deforma-
tion should be controlled by the recognition of the fact that many
cubic feet of the shale must be displaced to permit of the growth
of the larger concretions. We know of no reactions by which
replacement of argillaceous material by slow molecular inter-
change with carbonate of lime may take place, nor can we con-
ceive of such large spherical and spheroidal cavities as those
necessary for the segregation of the calcite as having antedated
the segregation. The last supposition is particularly invalid,
for, in any case, it would leave the radial structure unexplained.

The same objection may be made to the hypothesis that
energy sufficient for the deformation of the strata might be forth-
coming in the process of forming a pseudomorph of calcite after
some other carbonate of greater density. Siderite does, indeed,
occur in radially concretionary form in the Black Shale of Michi-
gan. But, while there might be an important increase of volume
with the application of expansive energy analogous to that ensu-
ing on the change from anhydrite to gypsum, we have still to
account for the original displacement of the shale to make way
for the siderite or other earlier carbonate itself. It may also be
stated that the disturbance of the shale is visibly greater than is
possible on a mere change of volume in the pseudomorphosing
reaction.

There thus seems to be no escape from the conclusion that
the crystallization of each concretion and the opening of the

‘Op. cit., p. 155. AO} Cilin, [Bs GG.

3 NEWBERRY’S largest concretion of the sort here described, and occurring under
similar conditions, measures 10 feet in diameter, giving a volume of more than 500

cubic feet. Geology of Ohio, 1873, p. 155.
4Geol. Surv., Mich., Vol. III, 1873-1876, p. 67.

144 REGINALD A. DALY

space in which it lies were contemporaneous processes ; the force
used in deforming the beds must, in some way or other, be
directly connected with the act of crystallization of the
Gallente:

The theory of this association that hes nearest to hand would
explain it by deriving active mechanical energy from each crystal
of calcite as it obtains new material at the outer extremity on
the surface of the growing spheroid. This energy will, then, be
that of a “live force,’”’ and will be directed centrifugally, forcing
the shale to assume a position dependent on the relative rate
Of Srowth wot the crystals) the bundles, wit wthiere be veqall
supply of carbonate in the surrounding matrix, the radiating
crystals will grow at equal rates; the aggregate will be spherical,
and the layers of shale will be forced to assume a corresponding
position. A rate of supply more rapid along the plane of strati-
fication than in a direction transverse to that plane would give a
spheroid with a minimum diameter similarly transverse to the
bedding, and a corresponding distortion of the shale mantle.
In brief, this hypothesis calls for the production of a com-
pressive force exerted on the surrounding medium by a growing
crystal.

Bischof has said that ‘‘what we know of causes in the growth
of crystals, we have learned in the chemical laboratory. This is
our sole guide to a conception of crystallization in the mineral
kingdom.”’* It must be confessed that the advocates of the
theory of live force exerted by natural crystals have been few,
and that almost all derive their whole argument from observa-
tions in the geological field, and not from those in the chemical
laboratory. Unfortunately, too, many of the examples chosen
by them cannot be taken as sure evidence of the exertion of
such force by a crystal of a primary mineral, z.¢., one that has
gathered its molecules, one by one, from a mother liquor, and
that by virtue of the attraction of like molecule to like. And
this is the case with our calcite molecule. With but few excep-
tions the argument for live force has been taken from the study

* Lehrbuch der chem. phys. Geologie, 2d ed., Band I, p. 140.

CAL OA KH SICONGRMELIONS OLN KERIEE POLNT. (145

of minerals like wavellite, natrolite, and other zeolites, gypsum,
serpentine, talc, and other hydrous secondary minerals ; possibly
pseudomorphs in every case, and if so, of less density, and occu-
pying greater volume than the parent mineral. Such swelling
substance can exert active centrifugal force. But we have
already noted the fact that this cause of crowding in rock-masses
cannot aid us greatly in explaining the Kettle Point con-
cretions.

Basing his statement on such doubtful examples as those just
mentioned, Bischof says: ‘Crystallization is a force which may
be compared with that of the expansive force of heat.’’? On the
other hand, he quotes Kopp, who opposed Duvernoy in his theory
of a mechanical energy of crystallization by showing that a crys-
tal of alum growing in a vessel never does so by accretion on
the face upon which the crystal rests at the bottom of the vessel.
Kopp thus concluded that the mechanical energy of crystalliza-
tion must be very slight, if existent at all, in this case, of a crystal
of exceptional rapidity of growth that cannot overcome its own
trifling weight when immersed in the mother-liquor.*

At the same time, certain observers have noted instances
where live force seems to have been exerted during growth by
crystals or crystalline aggregates, which may not, or, indeed,
certainly have not, been pseudomorphous derivatives from pre-
existing minerals. De La Béche, speaking of crystalline con-
cretions of selenite and of iron pyrites, stated his belief that, in
these cases, chemical affinity was strong enough ‘to overcome
the attraction of cohesion” in the matrix.* Dana’s example of
rifting of quartzite by the growth of a limonitic deposit, and the
wedging asunder of parts of a tourmaline crystal by the crys-
tallization of quartz in which the tourmaline lies embedded, are
too well known to need more than mention.3 Similarly, Worthen’s
disjointed crinoids, the plates of which were gradually separated
by the deposition of quartz between them, are cited by Dana as

1 BiscHoF, Lehrbuch, Band I, p. 134.

2 Researches in Theoretical Geology, 1834, p. 91.

3 Manual of Geology, 4th ed., p. 138.

146 KEGINALD A DALY:

proving displacement by the force of crystallization. More
recently, Professor Shaler has appealed to the hypothesis of
tensional force to explain the opening of certain vein-fissures,
the latter not being explicable by the usually accepted idea of
open fissures."

In certain of these cases, it may be agreed that the mechani-
cal force expended seems to have been applied pari passu with
the process of crystallization ; so far as I have been able to find
direct statement of the mode of application, each writer signifies
his belief that the crystal itself did the work of rifting or of
crowding together. We have seen that what little experimenta-
tion has already been carried out so far, leaves this interpretation
decidedly weakened. The question arises as to whether the
energy is set free in the act of crystallization in ways other than
-in the form of a push exerted by the growing crystal. An
answer has suggested itself to me, and I shall briefly out-
line it, without, I trust,seeming to imply that the idea is any-
thing more than a somewhat highly specialized working
hypothesis.

In the Kettle Point shales, saturation of the underground
waters by both free and combined carbon dioxide is not hard to
imagine. An abundant supply of the gas could be found in the
decomposition of the carbonaceous matter in the shales ;? the
monocarbonate of lime is supplied in all necessary quantity
from the calcareous bands in the shale and from the underlying
Devonian limestones.

Suppose now that a small fragment of carbonate of lime,
organic or other, is enclosed in a rock, with a capillary film
between mineral and rock. This fragment will act as the imme-
diate stimulus to the decomposition of any sufficiently saturated

* Bull. Geol. Soc. Amer., 1899, Vol. X, p. 259.

? The analysis of the gas given off from the “east crater”? among the Mississippi
mud-lumps of 1871 gave the following result: CO, 9.41 per cent., marsh gas 86.20 |
per cent., N 4.39 per cent. HILGARD, Amer. Jour. Science, 1871, (1) p. 426. While
the percentage of CO, is high, we may still regard this analysis as representative
of the normal gases given off in the decomposition of vegetable matter buried in
mud.

CALCAREOUS CONCRETIONS. OF KETTLE POINT 147

bicarbonated water that may be in contact with it.’ Monocar-
bonate is precipitated about the fragment and a double biproduct
is formed of water less strongly charged with the bicarbonate
than before, and of carbon dioxide, which may be kept in solu-
tion in the water. The volume of new monocarbonate, together
with that of the biproducts, is greater than that of the original
bicarbonate ;* expansion is necessary. The result would be the
development of pressure directed centrifugally with respect to
the fragment. This pressure will be the sum of all those minor
pressures produced by the single decompositions of bicarbonated
water entering by each of a million passages to the point where
the solid carbonate is reached. The integrated force may have
great efficiency. It would tend to expel the water from the sur-
rounding capillary passages. If the expulsion kept pace with the
crystallization, the space between the mineral and the adjacent
rock-substance would soon be completely closed and crystalliza-
tion and growth of the concretion would cease.

But the experiments of Jamin? have proved that equilibrium
may exist between two unequal pressures affecting the ends of a
capillary tube, provided a column of liquid occupying the tube
be interrupted by bubbles of air. The presence of the latter
excites capillary attraction which is so strong as to take up

It is a familiar fact that crystallization can often be brought about, when not
produced by other means, by introducing a crystal of the substance, the crystallizing
of which is desired. Further, the mass of substance dissolved in water and coming
in contact with a mineral, is very small compared with that of the mineral; if there
ensue a chemical reaction, it is the large mass of the mineral that regulates the laws of
affinity. Thus, solid carbonate of barium decomposes dissolved bicarbonate of
calcium, and solid calcium carbonate decomposes dissolved barium carbonate ;

4 fortiori, solid calcium carbonate will decompose dissolved calcium carbonate, i. e.,
the bicarbonate. Cf. BiscHor, Lehrbuch, Band I, p. 114.

2 That expansion will result has unfortunately not yet been proved by experiment
in the case of CaCOg, but it is inferred from the law that expansion of volume follows
on the separation of salts from their solutions in those instances where increased pres-
sure aids solubility. Engel has determined that the solubility of carbonate of lime
in carbonated water increases very rapidly with an increase of pressure, e. g.,
doubling with a rise of pressure from one to six atmospheres. Comptes Rendus, Vol.
Cl, p. 949.

3Comptes Rendus, Tome L, 1860, pp. 172 and 311.

148 VAR CIIMAIEIO) él, JOVAIL VG

several atmospheres of pressure applied at one end of the tube.
The force so expended is represented in the compression of the
air bubbles and in changing the form of the air menisci; surface
tension is thus overcome. The movement of the bubbles pro-
gressively decreases in the direction of the greater pressure until
one is reached which is not disturbed at all so long as the pres-
sures remain constant. The bubbles act lke so many buffers.
Any capillary tube filled with water interrupted by any insoluble
gas or liquid possessing a lower surface tension than water, will
exhibit the same phenomenon. Let us return to our incipient
concretion.

Round about the grain of carbonate, there is an infinite net-
work of capillary passages largely occupied by water in the
early history of the rock. Along with the water, are gaseous
and liquid hydrocarbons that are slowly being evolved by the
decomposition of organic matter. The distribution of the hydro-
carbons will be such as to bring about capillary attraction, and
therewith the possibility of differential pressures within the
water-mass, though it be in equilibrium throughout. Thus at
the capillary film separating lime fragment and argillaceous wall,
we may have great outward pressure unaccompanied by the
expulsion of water along the channels leading from the country
rock to the fragment. The latter is girt about with a mesh of
capillary passages enormously resistant to movement of the con-
tained liquids, and permitting of greater hydrostatic pressure
within than without. The form of the mesh itself may change
however, without interfering with its function as a buffer. The
centrifugal pressure will then be occupied in deforming the rock,
and it may conceivably be aided by the expansive energy of the
freed CO,. Fresh supplies of bicarbonated water will slowly
diffuse into the capillary space between concretion and rock and
further the displacing process. The solid carbonate as it were,
keeps pulling a trigger that sets off the reaction of decomposi-
tion, which does not occur at a distance from the fragment.
The biproduct cannot escape as fast as formed and the country-
rock must be crowded away. The deformation is then, analogous

CALCAREOUS CONCRETIONS OF KETTEE POINT 149

to that produced by the freezing of water in a closed vessel,
being caused by a change of volume, and not by the thrust of
the crystals as such.

Much of this general scheme can be applied with certainty
to the Kettle Point concretions. Bicarbonated water unques-
tionably was the source of the calcite substance; the decompo-
sition was induced locally at the call of pre-existent carbonate,
and the double biproduct described must have resulted. Since
the joints in the shale are undoubtedly due to desiccation, it is
but fair to suppose that the concretions antedate them. The
presence of hydrocarbons during the concretionary growth is
likewise.reasonable. The resulting surface tension in this deep-
lying water would thus bring about capillary action which was
especially powerful on account of the extremely small size of
the channels through which water could migrate in the shale.

The shape of the growing concretions will depend primarily
on the resistances offered to displacement by the shale, and, per-
haps, secondarily, to the rate of supply of bicarbonate. From
the homogeneous character of the shale, we are led to believe
that both of these actions will be nearly equal in all directions
throughout the rock, with, however, a slight advantage in power
of resistance to be ascribed to the direction at right angles to
the plane of stratification. The resulting form of the concre-
tions would, in consequence, be that of a sphere or of a spheroid.
The calcite crystals will assume radial positions according fora
law of crystal growth that does not concern us here; they will
grow outward into the shallow space offered by the outward
thrust until the biproduct has slowly diffused through the argil-
laceous wall.

In conclusion, then, it may be stated that the concretions
were formed in place within the shale, that they antedate the
period of joint development and final consolidation of the sur-
rounding rock, that the local deformation of the shale accompa-
nied the process of crystallization, and that the energy of the
deformation appears to have been derived from the change of
volume induced by the breaking up of the bicarbonate into

150 SIR ESONGAWILID) JH, JOVAIE SZ.

monocarbonate and fluid biproduct. The introduction of capil-
larity to explain the existence of differential pressures in the
rock-mass cannot be regarded as other than hypothetical. It is
hoped that the suggestion may lead to fruitful experimentation ;
for it is doubtless to the experimental geologist and to the
physical chemist that we must finally appeal in determining the
source of mechanical energy in deep-seated chemical reactions.
The hypothesis should, of course, also be tested by reference to
the conditions at other localities where deformation in sedi-
mentary rocks has been produced during the growth of concre-
tions, whether composed of calcite or of other material.
REGINALD A. DALY.

Noes GH OLOGICEAGE NiSeINTT Hy EROPIES

A FEW years ago in treating the subject of the decomposi-
tion of rocks in Brazil I spoke of ants as geologic agents worthy
of consideration’ My claims for these humble workers were
apparently accepted under protest. With this protest I confess
I have much sympathy, for if I had not seen with my Own eyes
so much of these ants and their remarkable deeds I never should
have believed half the stories told of them.

Last summer while visiting Brazil again ‘I made a few notes
upon the ant-hills in the State of Minas Geraes, and took a
photograph showing the kinds
of hills so common in certain
parts of that state. I went into

the interior at one place by the
Bahia and Minas railway, An ant-hill at Uruct station, Bahia and
which, starting from the coast ee ee
near Caravellas in the State of Bahia, runs to Theophilo Ottoni
(formerly called Philadelphia) in the State of Minas, a distance
of 376 kilometers. The first 160 kilometers of the road is over
campos of hard baked Cretaceous clays with only patches of
forest here and there. Beyond this the rocks are crystalline,
mostly gabbros and gneisses, up nearly to the end of the line
where the rocks are old metamorphic mica schists, itacolumites,
etc., all deeply decomposed. Shortly after leaving the Creta-
ceous area my attention was attracted by the big ant-hills in the
forests. These mounds are from three to fourteen feet high and
from ten to thirty feet across at the base. The new ones are
steeply conical and the old ones are rounded or flattened down
by the weather. In many places these mounds are so close
together that their bases touch each other.

About Urucut station (k. 226) the ant-hills are so thick that
the country looks like a field of gigantic potato hills.

*Decomposition of rocks in Brazil, by J. C. BRANNER: Bul. Geol. Soc. Amer.»
1896, VII, 295-300.
I51

152 Woo Go LRIRAUINIMIGIR,

In the vicinity of the city of Theophilo Ottoni there are
several old fields apparently abandoned to the ants. The
accompanying plate is from a photograph taken on the slope of
the hills west of the railway station at this city. The mounds
here are all low and rounded as if they were old.

I regret that this picture does not give a better idea of the
size and abundance of the ant-hills; unfortunately it was taken
when the sun was
almost directly
overhead,and the
view is up the

slope and along
themside on mtic
hill Beronemtne
photograph was made the man in foreground was sent behind

Ant-hills in an old field on the Rio Mucury, State of
Minas Geraes, Brazil.

the hill at the foot of which he sits, but though he was over six
feet high I could only see the top of his hat. The black lumps
shown are hard masses weathered from the large mounds.

In the city of Theophilo Ottoni the streets are cut down in
many places through the rock decayed in places. In some of the
fresh cuts I observed the holes made by ants penetrating the
ground in one place to a depth of ten feet, in another to a depth
of thirteen feet, below the surface of the ground; many others
were seen at a depth of six, seven and eight feet below the sur-
face.

It goes without saying that the ants do not bore into the hard
undecayed rocks, but it seems reasonable to suppose that the
opening up of the ground by their long and ramifying under-
ground passages hastens decay, and that the working over of
the soil must contribute more or less to the same end.

The impression one gets from the work of the ants along the
line of the Bahia and Minas railway —and for that matter in any
other part of the tropics—is that they are vastly more important
as geologic agents than the earthworms of temperate regions.

Since the publication of my paper upon the decomposition of
rocks in Brazil, in which several writers are quoted upon the work

ANIS AS GEOLOGIC AGENTS IN THE TROPICS 153

of ants inthat country, I have found a few interesting notes upon
the subject some of which I quote here.

Speaking of the ants inthe River Plate country Sir Woodbine
Parish refers to ‘‘Corrientes and Paraguay, where whole plains
are covered with their dome-like and conical edifices, rising five
and six feet in height.

yy

Ant-hills on the hills west of the city of Theophilo Ottoni, State of Minas Geraes,
Brazil.

The Robertsons mention ants’ nests among the palms near
Assuncion, Paraguay, as ‘‘thousands of conic masses of earth, to
the height of eight and ten feet, and having a base of nearly five
in diameter.’’?

Referring to the injury done to crops by the sauba ants the
president of the Imperial Instituto Fluminense de Agricultura
says: ‘‘Among the obstacles with which planters have to con-
tend . . . . there stands perhaps in the front ranks the destruc-
tive force represented by the sauba.’’3 Joun C. BRANNER.

tBuenos Ayres and the provinces of the Rio de la Plata, by StR WOODBINE
PARISH: 2d ed., p. 252. London, 1852.

? Letters on Paraguay, by J. P. and W. P. RoBERTSON, Vol. I, 270-274. Lon-
don, 1838.

3 Henrique de Paulo Mascarenhas in the Revista Agricola do Imperial Instituto,
December 1883, XVI, 215.

WeEUSIOEINIOINS (QUe GILACIISIRS, Wo

TuE following is a summary of the fourth annual LepORt ote
the International Committee on Glaciers :?

RECORD OF GLACIERS FOR 1898

Swiss Alps.— Of the seventy glaciers which were measured
in 1898, twelve are advancing, fifty-five retreating and the others
doubtful.3

Eastern Alps—YVhe variations reported last year on the
Gliederferner and Vernagtferner are confirmed by further meas-
ures. The swelling of these glaciers continues to advance down
the valley and to carry with it an increased velocity of motion.
~ When it reaches the end of the glacier there will be an advance
Onwthenice hic majority of the glaciers are retreating, though
a few of them are advancing. On the whole the tendency to
retreat seems to be increasing.*

ftahan Alps.—The glaciers of Mount Disgrazia, and those of
the south side of the Bernina group are all retreating at the rate
of several meters a year.

Scandinavian Alps.—The glaciers of Sweden so far as observed
show insignificant changes. They are probably stationary. The
velocity of the Stuorajekna near its end was found to be about
twice as rapid in summer as the annual average.®

Polar Regions.—In 1898, the large glacier between Mt.
Hedgehog and South Cape, Spitzbergen, was found to project
several kilometers into the sea. This glacier is not shown on
former maps, and it is therefore possible that it has recently
made a great advance.’

*The first four articles of this series appeared in this JouRNAL, Vol. III, pp.
278-288; Vol. V, pp. 378-383; Vol. VI, pp. 473-476, and Vol. VII, pp. 217-225.

2 Archives des Sciences Phys. et Nat., Vol. VIII, pp. 85-115.

3 Report of Professor Forel.

4 Report of Professor Finsterwalder. °Report of Dr. Svenonius.

5 Report of Professor Marinelli. 7 Report of Dr. Nathorst.

154

VARIATIONS OF GLACIERS 155

Greenland.— Steenstrup and Drygalski have both concluded
from their observations, that the great cold of winter greatly
reduces the velocity of motion df the smaller glaciers, but that
the large glaciers, nourished by the inland ice, are very little
affected by the seasons. Drygalski has found a velocity of
twenty meters per day in the great Karajak glacier. The Asakak
glacier on the Nugsuak Peninsula has been observed at intervals
for fifty years. It retreated nearly a kilometer between 1849 and
1879, and has since then advanced even more. The Sermiarsut
glacier no longer reaches tide water as it formerly did, but the
other small glaciers of this region show no marked changes.
The Blase Dale glaciers on the island of Disco, have continued
to retreat since the visit of Professor Chamberlin in 1894."

Canada.— The Upper Bow glacier is slowly advancing, but it
has not yet reached the extent indicated by former moraines.
Freshfield glacier was advancing in 1897, plowing up the débris
in front. Stutfield glacier has been covered with débris by great
avalanches, and the melting has thus been retarded. Asa result
the ice is advancing down the valley and is now in the midst of
the forest. It is at least a half mile beyond its former limits.
The Illecellewaet glacier has retreated 100 to 150 meters since
1888, and probably 200 meters within the present century.

Fitmalaya.— The Yarsching glacier apparently retreated
between 1850 and 1870, at which latter date it was advancing.
It seems to be advancing at present and may block up the valley
above it, and cause inundations as it has done before.

Africa.— Dr. Hans Meyer visited the cone of Kibo, the
highest point of Kilimanjaro, in 1898 and described the extent
of its glaciers. The summit is about 6000 meters high, and the
ice streams down on all sides. On the northern and eastern
sides the winds are dry, and the glaciers only descend a few
hundred meters; whereas on the southern and southwestern
sides, the winds are moist and one glacier descends as much as
2000 meters from the summit. There has beena distinct retreat
since Dr. Meyer’s visit in 1889. Dr. Meyer has also discovered

* Report of Dr. Steenstrup.

156 H. F. REID

traces of a glacial period on Kilimanjaro, which confirms similar
observations of Gregory further north on Kenia."

Caucasus.— The glaciers in the neighborhood of Mt. Elbruz
are retreating at the rate of eight or ten meters a year, with the
exception of the Adyl, which has advanced six or seven meters
between 1897 and 1808.?

REPORT ON THE GLACIERS OF THE UNITED STATES FOR 18903

Montana.— Sperry glacier, discovered a few years ago, is
retreating —(L. B. Sperry).

Mt. Adams, Wash.— This volcanic peak, like the others of this
region, has a number of glaciers streaming down its sides. The
White Salmon and the Mazama, respectively, on the southwestern
and southern slopes of the mountain, are broad and compara-
tively short masses of ice. Each divides into two tongues. The
‘White Salmon is largely covered with débris, while the surface
of the Mazama is clean to its ends, though it has a large lateral
moraine. The causes of these differences do not appear.

On the eastern side of the mountain are the Klickitat and
Rusk glaciers, both of which lie in deep canyons. They are two
or three miles long, the latter being the shorter. The Klickitat
is connected with the ice-cap of the mountain through three
couloirs, and is also nourished by ice avalanches which fall down
the great precipice which characterizes the eastern side of the
mountain. The Rusk derives all its material from avalanches.
Neither are free of moraines. The other slopes of the mountain
are not cut into ravines and the glaciers on the northern side,
probably four in number, are not very distinctly separated from
each other; they are also thoroughly covered with débris, so
that they could not be readily distinguished from a distance.

The Klickitat glacier was retreating in 1890 (C. Z. Rusk), but
no information is available regarding the variations of the others.‘

tReport of Mr. Norman Collie. ? Report of Mr. Mouchketow.

3 A synopsis of his report will appear in the Fifth Annual Report of the Inter-
national Committee. The report on the glaciers of the United States for 1898 was
given in this JOURNAL, Vol. VII, pp. 221-225.

4The account of these glaciers is taken from descriptions by Professor W. D.
Lyman and Mr. C. E. Rusk in the Mazama Magazine, Vol. I, and from a special com-
munication from Mr. Rusk.

VARIATIONS OF GLACIERS 157

Mt. St. Helens.—A glacier on the north side of this mountain
was advancing and destroying trees in 1895 (C. Z. Rusk).

Mount Ranier.—The Nisqually glacier has retreated not less
than 100 meters since 1894 (4. 7. Allen).

Alaska.— Last summer, Mr. E. H. Harrington of New York,
invited a number of scientific men to accompany him on a

voyage along the Alaskan coast. The full results of the expe-
dition are to be published by the Washington Academy of
Sciences. .

Twenty-two tide-water glaciers were examined and marks
left near many of them by which future changes may be
measured.

Photographs and observations made by several members of
the expedition show that all the glaciers visited are now retreat-
ing except the Crillon glacier on the west side of Mt. Crillon.
This glacier does not reach tide-water; it is advancing against
the forest and destroying the trees.

Prince Wilham Sound.— Mr. Gannett mapped the glaciers and
found that they are all retreating. The Harvard and Yale
glaciers have retreated nine miles in a century."

The Columbia glacier is now retreating, but the disturbed
ground in front of it shows that it has recently advanced. The
young trees growing on this disturbed surface place the date of
the advance eight or nine years ago. The Muir glacier made an
advance about the same time (G. K. Gilbert).

Glacier Bay.—Al\l the glaciers seem to be retreating. In
18709, the three glaciers at the head of the bay were united and
three or four miles in advance of their present positions. The
Charpentier and Hugh Miller also formed one glacier and
extended two or three miles further than they now do. Rendu
and Carroll glaciers have suffered decided recessions since 1896
(John Muzr) .

A comparison of photographs taken by Mr. Gilbert in 1899,
with others taken by the author in 1892, shows that in that

tThe Harriman Alaska Expedition, by Henry Gannett, Nat. Geog. Mag., 1899,
Vol. X, pp. 507-512; and Bull. Amer. Geograph. Soc., 1899, Vol. XXXI, pp. 345-

355:

158 H. F. REID

interval, the Grand Pacific glacier has retreated 500 to 600
yards; and the Hugh Miller 300 to 400 yards; the tide-water
end of the Charpentier has receded nearly a mile and the Alpine
end is now a mass of disconnected dead ice.

The records of Muir glacier are increasing. We know
approximately its extent in 1880 from Professor Muir; and in
1886 from photographs by Professor Wright; and accurately in
1890 and 1892 from surveys by the author; pretty well in 1894
from photographs by La Roche of Seattle, and accurately again
in 1899 from surveys by Mr. Gannett. With the exception of a
slight advance between 1890 and 1892 the glacier has been
pretty steadily receding. At present its extreme point in the
middle of the inlet is not much behind its position eight or ten
years ago, but the sides have receded fully half a mile. Morse
glacier, a tributary on the west, became entirely separated from
Muir glacier between 1892 and 1894 and continues to get
shorter. Dirt glacier will probably also be an independent
glacier before long.

Mr. Otto J. Klotz, of the Canadian Topographical Survey,
concludes from a comparison of Vancouver’s description of
Taylor Bay with its present extent, that the Brady glacier in
1794 was at least five miles shorter than in 1893, when the
Canadian survey was made, and that at the earlier date the
glacier ended in tide-water. At present its end rests on gravels
and does not quite reach the sea. These gravels must then have
been laid down in the interval. He also concludes from Van-
couver’s descriptions and that of Sir George Simpson regarding
Stephens’ passage in 1841, that all the glaciers south of Fair-
weather Range have been steadily retreating in the last century.
This, however, does not preclude temporary advances of indi-
vidual glaciers, such as the Patterson, which, according to the
Pacific Coast Pilot of 1891, was advancing and destroying trees
at that time. The Le Conte glacier is at the head of a fiord
about six miles long, and has retreated about half a mile between
1887, when the United States Coast and Geodetic Survey chart
was made, and moe, the time ofthe) Canadianyisunveyamect

VARIATIONS OF GLACIERS 159

description of this region by Vancouver does not give any
reference to this fiord. It is therefore probable that it was

entirely filled with ice a hundred years ago, which would indicate
a retreat of Le Conte glacier of six miles in a century.*

Harry FIELDING REID.
GEOLOGICAL LABORATORY,
JoHNs Hopkins UNIVERSITY,
March 22, I900.

* Notes on Glaciers of Southeastern Alaska and Adjoining Territory, by OrTo J.
Kotz: Geog. Jour., 1899, Vol. XIV, pp. 523-534.

STUDIES PORT SRODENIES

WSUS INOMSIRIINTS, Ol8 IVIICIDIUNG SOQWISS AINID
MERHODS7OF DETRERMINENG WE DRA VeAvIe Ui

I. NECESSARY CONSIDERATIONS IN THE SELECTION OF -STONE

Quarry observations, building inspection, and laboratory
examination of building stone are conducted to satisfy the
individual and the public that the stone under consideration
possesses a color which will remain permanent and inherent
qualities which give it a capacity to effectually withstand the
atmospheric and other conditions to which it will be subject
when in use.

It is my purpose in this number to discuss: (1) Color; (2)
the inherent qualities of stone which limit its capacity to with-
stand atmospheric and other conditions; and (3) the atmos-
pheric and other conditions to which building stone may be
subject. Ina following number quarry observations, building
inspection, and the laboratory examination of building stone
will be considered.

‘This subject has been discussed very freely by geologists, architects, and engi-
neers for twenty or twenty-five years. Many of the ideas expressed in this and the
following number are a repetition of the conclusions reached by men who have previ-
ously entered this field of discussion. However, it would be a very uncertain task to
endeavor to give any one credit for first enunciating the principles herein stated.

The following is a list of the more important American publications which treat,
more or less fully, the subject considered in these studies, and to which the reader is
referred: The Experimental Tests of Building Stones, by ROBERT G. HATFIELD,
Trans. Am. Soc. of Civil Engineers, Vol. XLVIII, pp. 145-151, 1872; Report on the
Building Stones of the United States, Appendix of the Annual Report of the Chief
of Engineers, U.S. A., 1875; Notes on Building Stones, by H1rAM A. CUTTING, Ver-
mont, 1880; Building Stones of Colorado, by REGIS CHAUVENET, Report of the
Colorado School of Mines, pp. 1-16, 1884; The Building Stones of Minnesota, by N.
H. WINCHELL, Report of the Geological and Natural History Survey of Minnesota,
Vol. I, pp. 142-203, 1884; Special Report on Petroleum, Coke, and Building Stone,
The Tenth Census of the United States, 1884; Report on Building Stones, by JAMES
HALL, Thirty-ninth Annual Report of the New York State Museum of Natural History,

160

THE PROPERTIES ‘OF BUILDING STONES, ETC. 161

Color.
brown, red, yellow, buff, blue, black, and green.* Ordinarily

The predominant colors of stone are white, gray,

the color of a rock is not simple but composite, being a resultant
of the different colors of the constituent minerals.

The sedimentary rocks on account of the simplicity of their
mineral composition approach more nearly to what is known as
a simple color than do the igneous. The shades of brown, buff,
yellow, red, gray, or blue imparted by a sedimentary rock are
mainly attributable to the presence of the oxide, carbonate, or
sulphide of iron, bitumen, and carbonaceous matter in the form
of graphite. The white and gray colors of marble, limestone,
and dolomite may be attributed to the calcite or dolomite of
which the rock may be composed.

pp. 186-224, 1886; The Collection of Building and Ornamental Stones in the United
States National Museum, by GEORGE P. MERRILL, Smithsonian Report, Part I, pp.
277-520 1886; Igneous Rocks, by J. F. WILLIAMS, Annual Report of the Arkansas Geo-
logical Survey, Vol. II, 1890; Building Stone in the State of New York, by JoHN C.
Smock, Bulletin of the New York Museum of Natural History, Vol. III, No. 10, 1890;
Marbles and Other Limestones, by T. C. HopKins, Report of the Arkansas Geological
Survey, Vol. IV, 1890; Stones for Building and Decoration, by GEORGE P. MERRILL,
John Wiley and Sons, 1891 and 1898; The Onyx Marbles, by GEORGE P. MERRILL,
Report of the United States National Museum, pp. 539-585, 1893; Marbles of
Georgia, by S. W. McCALLtE, Bulletin No. 1 of the Geological Survey of Georgia, 1894;
Notes upon Testing Building Stones, by T. LyNNwoop GarRIsON, Trans. Am. Soc. of
Civil Engineers, Vol. XXXII, pp. 87-98, 1894; The Relative Effect of Frost and the
Sulphate of Soda Efflorescence Tests on Building Stones, by LEA McI. LuqQuEr,
Trans. Am. Soc. of Civil Engineers, Vol. XXXIII, pp. 235-256, 1895; Report on
Tests of Metals, etc., at Watertown Arsenal; Reports of the United States War
Department, pp. 322, 323, 1895; also 1890 and 1894; The Building Materials of
Pennsylvania; I, Brownstones, by T. C. HopPKINs, Appendix to the Annual Report of
Pennsylvania State College for 1896; The Bedford Oolitic Limestones of Indiana, by
T. C. Hopkins and C. E. SIEBENTHAL, Twenty-first Annual Report of the Depart-
ment of Geology and Natural Resources of Indiana, pp. 290-427, 1896; Properties
and Tests of Building Stones, by H. F. Bain, Eighth Annual Report of the Iowa
Geological Survey, 1898; The Building and Decorative Stones of Maryland, by
GrEorGE P. MERRILL and EpwARD B. MATHEWS, Report of the Maryland Geological
Survey, Vol. II, pp. 47-237, 1898; The Building and Ornamental Stones of Wiscon-
sin, by E. R. BUCKLEY, Wisconsin Geological and Natural History Survey, Bulletin
No. IV, 1898. Reference should also be made to the Engineering, Mining, Archi-
tectural, Building, Stone, and similar technical journals in which this subject is dis-
cussed in current articles.

«Speaking from the purely scientific standpoint all of these are not colors,.
although they are referred to as such in this paper.

162 SLODIES HOR SLO DEN ES:

When iron occurs in sedimentary rocks, more especially
sandstone, it often serves as a cement by which the original
particles are bound together. However, it may also occur as an
original constituent in the shape of finely disseminated particles.
Carbonaceous matter in the form of graphite, or bitumen in the
shape of petroleum occurs mainly in limestone and marble, often
contributing to these rocks the blue or grayish-blue colors so
commonly observed.

Among sedimentary rocks the color varies widely, not only
in the same quarry, but often in the same bed. Certain beds in
a quarry may have a delightfully cheerful, uniform color, while
those immediately above or below may be dull and somber. In
many places the coloring matter is distributed through the beds
in regular bands, but occasionally it is very curiously dissemi-
nated, forming irregular, fantastic figures. White sandstone is
often colored with large and small brown spots, while brown
sandstone is sometimes similarly variegated with white spots.
All stone which is distinctly mottled or irregularly colored is
known as ‘‘variegated stone.”

The color of an igneous rock is usually composite, as a result
of the blending of the distinct colors of the mineral particles.
The color, however, does not depend entirely upon the colors of
the individual minerals, but in part upon the size and distribu-
tion of the constituent particles. In some instances the individ-
ual grains are sufficiently large to retain their own color, and
the stone is spoken of as being mottled.

With respect to color, granites are ordinarily classified as red
and gray. Whether a granite belongs to the first or second class
will depend mainly upon the red or white color of the feldspar.
Many granites contain both red and white feldspar, but as long
as the red variety is sufficiently abundant to impart a reddish
tone to the rock, it is called red granite. The most brilliant red
granites have a preponderance of medium-sized, deep red feld-
spar individuals. As the feldspar individuals become finer
grained and less deeply colored and biotite, amphibole, or
pyroxene becomes more abundant, the color is subdued produc-
ing dull red effects.

THE PROPERTIES OF BUILDING STONES, ETC. 163

The gray granites are dark or light colored, depending upon
the size of the individual grains and the amount and kind of
the ferro-magnesian minerals present. The light-colored granites
have a preponderance of white feldspar and quartz, with musco-
vite as the main ferro-magnesian mineral. The dark gray gran-
ites contain less feldspar and quartz, and a greater abundance of
biotite, hornblende, pyroxene.

Other igneous rocks such as Ee Paipradlorive: granite’ with its
blue iridescent color, and rhyolite with its almost black color,
are commonly met with. The iridescent color of the former is
imparted by the abundant porphyritic indiyiduals of labradorite,
of which the rock is largely composed. The black color of the
latter is due largely to its semi-crystalline groundmass, which
often abounds in fine crystals of hornblende. Serpentine is an
abundant constituent of some rocks, and as such imparts to them a
green color. The dull greenish-gray color so conspicuous among
the basic rocks such as gabbro, diorite, and diabase, is imparted
mainly by the minerals of the hornblende, pyroxene, amphibole,
chlorite, and epidote groups.

The color of arock when freshly quarried may be almost per-
fectly white but a few years, or perhaps months, of exposure to
the weather may change the color to a buff, or streak it with
irregular patches of brown. Such color changes result chiefly
from the presence of easily decomposed minerals within the stone
itself. The yellow color of many limestones is due to the pres-
ence of finely disseminated iron, as the carbonate or sulphide,
which has altered to the oxide. If a stone contains either of
these the color will change as a natural consequence of expo-
sure to the atmosphere. The oxides of iron are more stable
compounds than the sulphide or carbonate, and very seldom
cause a change in color.

A change in the color of the stone in a wall may be due to
impurities in the mortar, cement, brick, or water used in the con-
struction and not to the presence of easily decomposed minerals
in the stone. The committee appointed to investigate the cause
of the brown stains on the walls of the State Historical Library

164 STUDIES FOR STUDENTS:

Building at Madison, Wis., reported that the Bedford limestone,
out of which the building is constructed, was practically free from
ferrous iron, and that the cause of the iron staining was attribu-
table mainly to the cement used in the back wall. This is prob-
ably a frequent cause of discoloration, on account of which good
stone has been condemned. A common method of preventing
the ferrous iron in the brick or mortar of the back wall from
coming to the surface, is to use a coat of asphalt between this
and the stone facing. A better precaution would be to select
lime, cement, and brick from which ferrous lime is known to be
absent. :

A change of color through the decomposition of iron sulphide
and carbonate is manifest mainly among the light colored rocks.
The blue or gray limestones and dolomites are often discolored
-by spots or irregular efflorescent patches of calcium or magne-
sium sulphate, which appear as a white precipitate on the surface.
Their presence at this place is attributed to interstitial water,
which comes to the surface bearing soluble salts of magnesium
and calcium, mainly the former. Dark colored rocks such as
brown sandstone do not discolor, but occasionally they take ona
lighter tint after iong exposure to the weather. This comes
about through the loss of iron oxide which is washed off from
the surface by the rains. Decoloration, however, takes place so
slowly that it is not an important consideration.

Very often, through long exposure in the quarry a rock, such
as the blue limestone of the Trenton formation, is partly or
entirely altered in color to a buff. Near the surface, beds may
be found that have been completely altered, while deeper in the
quarry one passes from those that are partly altered to those
that are unchanged. The alteration commences along the joints
and gradually passes toward the center of the blocks.

The manner in which a stone is dressed sometimes affects the
permanency of itscolor. A rough dressed stone furnishes a mul-
titude of places in which dust and dirt may lodge, while one which
is smooth dressed is free from such places, For this reason there
is less danger of the original color being obscured in a smooth

TE ROLE iti SOL B CLEDING*SRONES;, Hi iG. 165

than in a rough dressed stone. On the other hand a smooth
dressed stone emphasizes blemishes in color which may be
obscured by rough dressing.’ These color blemishes may be
more unsightly than the ‘‘tan”’ of smut and dust, in which case
it would be preferable to rough dress the stone.

Fashion, dominated by color, influences the exploitation and
the market value of different stones. Until a few years ago
brownstone was preferred, both for business blocks and resi-
dences, but people became weary of gazing at long rows of som-
ber colored buildings and the fashion changed to light colored
stone. At the present time immense quantities of light colored
stone are being used, but the fashion will change again in a few
years and the pendulum will swing back to brownstone. A
judicious use of both would serve to relieve the monotony of
long rows of brownstone buildings and of the dazzling glare of
white limestone and marble. It is to be hoped that the time will
come when the use of neither light nor dark stone will be
supreme.

In the large cities, other things being equal, the permanence
of color ought to be a factor worthy of consideration in the erec-
tion of residences and tenement houses. However, in the con-
struction of business blocks it scarcely warrants serious attention.
A white limestone or marble structure erected in the midst of a
business portion of a large city soon loses its original color, becom-
ing gray and dingy from the omnipresent smoke and dirt. Ifthe
limestone is bituminous and contains a small amount of oil, all the
dust and smoke which chances to fall upon it will be retained.
The walls of most of the buildings in the business section of our
large cities eventually become so begrimed with smoke and dust
that it is barely possible to tell whether the stone was originally
dark or light colored. One needs to familiarize himself with the
characteristic brown and gray shades of stone which have been
steeped for years in a smoke and dust laden atmosphere, in order
to be able to determine the original colors.

On the whole the dark colored stone shows much less than
does the light the effects of smoke and dust. Nevertheless the

166 STUDIES FOR STUDENTS

only consideration in the selection of stone to be used in the
business portion of a large city should be strength and durability.

In the suburban and resident parts of a city and in rural dis-
tricts, where smoke and dust are trifling matters, the original
color will not suffer seriously from external causes alone. In
these places beauty is one of the chief ends of architecture, and
a judicious scattering of light and dark colored stone buildings
adds very materially not only to the appearance of the street as
a whole, but also to the beauty of the dwellings individually.

When used for interior decorations, a stone does not suffer
materially from atmospheric agencies, and the color will ordi-
narily remain permanent. The selection of stone for these uses,
then, becomes largely a question of taste. A color which har-
monizes with the surroundings or matches the other work, is
generally considered most appropriate. In the flooring or steps,
the capacity which the stone has to withstand abrasion without
becoming unduly slippery, and not color, should be the control-
ling factor.

For monumental purposes the taste of the purchaser is again
the main, controlling factor in the color selected. The stones
used for monuments are mainly igneous and metamorphic
(granite and marble), and as such contain few minerals which
will result in discoloration. If pyrite or marcasite are constit-
uents of the stone there will be danger of discoloration. How-
ever, the fact that most of the water which falls upon a granite
monument is shed by its polished surface, lessens the danger of
discoloration, by preventing decomposition.

In the more common uses to which stone is put, such as road
making, sidewalks, retaining walls, cribs, breakwaters, bridge
abutments, etc., the element of color seldom enters. In the
case of retaining walls and sidewalks, which are partially orna-
mental in nature, color should receive appropriate consideration.

Il. INHERENT QUALITIES OF STONE

The capacity which a stone has to withstand the forces tend-
ing to destroy it, is known as durability, and depends upon the

TAE PROPERTIES OF BULLEDING SHONES, ETC. 167

mineralogical composition, and the texture or state of aggrega-
tion of the mineral constituents. A consideration of the min-
eralogical composition implies reference to the characteristics of
the different kinds of minerals and their relative abundance.
By texture is meant the size, shape, manner of contact, and
arrangement of the mineral particles. The strength, hardness,
elasticity, structures, the effect of alternating heat and cold, and
the effect of acids, depend upon both the mineralogical compo-
sition and the texture. The specific gravity as ordinarily com-
puted depends upon the mineralogical composition alone; the
porosity on the texture; and the weight per cubic foot on the
specific gravity, and porosity."

Mineralogical composition The most common minerals that
enter into the composition of building stones are quartz, feld-
spar, mica, calcite, dolomite, kaolin; pyroxene, amphibole, and
serpentine. These minerals have a respective hardness of 7, 6,
2-3, 3, 3-5-4, I, 5-6, 5-6, 3-4. With the exception of quartz
they all have one or more well-developed cleavages.

Quartz is perhaps the commonest of these minerals. It is
the hardest, but probably neither the strongest nor most elastic.”
Under ordinary conditions of temperature and pressure it is little,
if at all, acted upon by the common acids. These conditions,
combined with the fact that it possesses no ready cleavage,
makes it one of the most durable and stable rock-forming min-
erals.

feldspar is also a very common mineral, especially in the
igneous rocks. It is softer than quartz, but probably stronger
and more elastic. It cleaves readily in two directions. Under
ordinary conditions of temperature and pressure it is little acted
upon by the common acids. In the quarry, decomposition of

*It has been customary to consider the minerals of igneous rocks as primary, and
secondary, while the secondary mineral matter in sedimentary rocks is known as

cement. In this paper minerals are considered without reference to their origin, and
therefore the terms secondary, primary, and cement, have been purposely omitted.

2Thus far I have been unable to obtain the crushing strength or coefficient of
elasticity of the common minerals. I expect that these constants have been deter-
mined although my attempts to obtain them have been unsuccessful.

168 SSM GOV ORS MOV SIKGUOVIINIES

feldspar takes place very slowly, but owing to the fact that it
often occurs in granite and other rock of great age, it is fre-
quently in an advanced stage of alteration. The alteration
products of feldspar are objectionable only in so far as they
yield more readily to disintegration.

Mica is also a very common mineral, occurring most abun-
dantly in the metamorphic rocks. The ready cleavage by which
the mineral splits into thin plates, provides an easy passage for ,
water, by which disintegration proceeds more rapidly than in
the associated minerals. Mica is undesirable in proportion to
the size of the individuals. If present in small isolated flakes, as
it ordinarily occurs in sandstone, it is scarcely less durable than
quartz and feldspar, but if the individuals are large or the flakes
clustered together, disintegration will proceed more rapidly.
Decomposition through chemical agencies goes on very slowly.

Calcite is almost as common as quartz, although far less per-
manent at the surface of the earth. It possesses three prominent
cleavage directions, on account of which it disintegrates quite
readily. The hardness, and probably the strength and elasticity,
are all less than in quartz. It is quite easily soluble in carbon-
ated waters and is readily acted upon by cold, dilute hydro-
chloric acid.

Dolomite differs from calcite mainly in its somewhat greater
hardness, and the greater difficulty with which it dissolves in
cold dilute hydrochloric acid. Its cleavage, hardness, strength,
and elasticity are such that it disintegrates almost as readily
as calcite, although it is taken into solution somewhat more
slowly.

Kaolin is an important constituent of slate, being however,
mainly of secondary origin. It is one of the softer minerals, has
a perfect cleavage, and readily disintegrates. It is not acted
upon chemically except under the most favorable conditions.

Pyroxene is one of the less important building-stone minerals.
It cleaves perfectly in two directions, and breaks down slowly
through mechanical abrasion. It gradually decomposes in the
quarry when in the presence of water.

THESRROPE RELIES, OF BULL DING (STONES, LC: 169

Amplubole has about the same strength and capacity to with-
stand abrasion and chemical influences as pyroxene.

Serpentine occurs in certain green colored rocks, such as verde
antique, and is usually an alteration product of olivine.

Among the accessory mineral substances in building stones
may be mentioned pyrite, marcasite, hematite, magnetite, graphite,
and bitumen. Pyrite and marcasite in which the iron occurs
partly in the ferrous state decompose quite readily in the pres-
ence of moisture, forming ferrous sulphate, which is brought to
the surface by capillarity and deposited as iron oxide. Through
the decomposition of pyrite, occurring in limestone or dolomite,
magnesium and calcium sulphates are formed, which are taken into
solution and redeposited at the surface as a white efflorescence.

Hematite and magnetite frequently impart a red, brown, yel-
low, or black color to the stone, but are not considered harmful.

Carbonaceous matter occurs in the form of graphite, and
bituminous matter in the form of petroleum. The gray and
black shades of limestone and marble are often due to the abun-
dance of graphite. Petroleum occurs mainly in limestone, and
is objectionable on account of the discoloration which is apt to
result from the adherence of dust.

The occurrence of gaseous inclusions in the minerals, espe-
cially in quartz, is said to be a cause for the shattering of a rock
when subjected to high temperatures. To what extent these
inclusions influence the results of high temperatures on rock is
unknown. The probability is that any temperature which would
make these gases active agents of destruction would destroy the
rock through unequal expansion of the mineral particles.

The hardness, strength, elasticity, and resistance of the stone
to chemical action and alternating temperatures is influenced by
the relative abundance of the mineral particles. If the percent-
age of quartz is large, the hardness is proportionately great—
provided the size, shape, arrangement, etc., are constant. The
strength and elasticity also increase as the minerals in which
these properties are best developed are increased. However,
it must be understood that a mineral which is high in the scale

170 STUDIES FOR STUDENTS

of hardness may have a comparatively low crushing strength and
elasticity. Any increase in the percentage of this material will
increase the hardness of the rock at the expense of strength and
elasticity. Of course, the elasticity, hardness, and strength are-
not controlled by the one factor of abundance. A rock may
consist entirely of the strongest minerals, and yet the size, man-
ner of contact, and arrangement may be such that it will be one
of the weakest.

TEXTURE OR STATE OF AGGREGATION

As outlined above the texture of a rock has reference to the
size, shape, manner of contact, and arrangement of the mineral
particles. The size of the particles affect the weathering of a
stone by increasing the differential disintegration. When the
mineral particles are large they disintegrate and weather out
‘most easily, often leaving small depressions, on account of which
the surface has a pitted appearance. The larger mineral par-
ticles have more pronounced cleavage cracks which increase the
rate of weathering. Chemical agents have a better chance to
operate and the stone is weakened throughout. Rocks which
are composed of small mineral particles may have correspond-
ingly small pore spaces, although the size of the pores is largely
controlled by the shape and manner of contact of the grains.

The shape and manner of contact of the grains influence
the strength and durability of the stone, as much perhaps as any
of its other qualities. If the grains are close fitting the adhesion
will be increased and the pore space decreased. When the
grains are irregular in outline they usually interlock after the
manner of dovetail work, which adds to the strength and lessens
the pore space.

Upon the arrangement of the grains depends the laminated
schistose, or cleavage structure in rocks. Ifthe mica or other
minerals are arranged with their longest axes in a common direc-
tion and concentrated along certain planes the rock will possess
a capacity to part most readily in that direction and along those
planes. The perfection of development of the parting capacity
will be influenced also by the size of the grains.

RTE LE ROPRERISES OF BOULLDING STONES, ETC. L7i

The size, shape, manner of contact, and arrangement of the
grains control the size of the pores and the percentage of pore
space.’ The porosity of a rock is an important factor, influen-
cing the danger from alternate freezing and thawing of included
water.

The pores, or spaces between the grains, which are connected
in such a manner as to allow water to‘ flow from one part to
another have been divided for convenience into three classes.

The first class consists of small interspaces that exist between
the grains of a rock, known as pore spaces; the second class
consists of those openings which form along bedding, jointing,
and fissile planes, known as sheet openings ; the third class are
those openings caused by the removal of several or many of the
individual grains, commonly known as cavities, caves, or cav-
erns. All of these openings frequently occur in the same
rock.

Pores are ordinarily conceived of as being connected so as
to form irregular-shaped tubes. Naturally they differ very
greatly in size, depending upon the fineness and shape of the
original particles composing the rock and the extent to which
the interstices have been filled with secondary mineral matter.
In the same rock all the pores are never of the same size,
although they may have a general correspondence in size. The
pores spaces are classified according to size into capillary and sub-
capillary. The capillary pores are the larger and the water which
they hold is known as the water of saturation. Openings
included in this class are over .00002 centimeter in diameter?
If a rock containing capillary pores is allowed to drain off natur-
ally, a portion of the water will escape, but another portion will

*It has been pointed out in another place that pore space in sedimentary rocks
depends largely upon the size and shape of the grains and the amount of cement. In
general this is true, but the cement itself becomes an individual grain, when once
deposited in the interspace of a rock, and the shape and size of the cement grains

should be considered. All particles of which a rock is composed should receive con-
sideration as constituent grains of the rock.

?Metamorphism of Rocks and Rock Flowage, C. R. VAN Hiss, Bulletin of the
Geological Society of America, Vol. IN, p. 272.

WP SIMOIDUES IPO iS IUIDIEIN IGS,

remain which is known as the water of imbibition. The sub-
capillary pores are conceived to be of sucha size, smaller than
.00002 centimeter in diameter, as to contain only the water of
imbibition.”

As in the case of pores, Professor Van Hise has classified
sheet openings which occur along bedding, jointing, or other
fissile planes, as capillary and subcapillary, including in the lat-
ter all such as are less than .oOOOI centimeter in thickness.?

The third class of openings consisting of cavities, caves, and
caverns are a result of the removal of one or more of the
grains of which a rock may have been originally composed.
They occur most commonly in limestone or dolomite, although
present in other less readily soluble rocks.

Ill. EXTERNAL CAUSES OF DECAY

In the selection of a stone for any purpose a consideration of
the climatic conditions under which it is to be placed, is of very
great importance. A uniform climate in which the temperature
is always above the freezing point is most favorable to long life.
A dry climate is conducive to stability, while a moist or humid
atmosphere promotes decay. A stone which will withstand the
vicissitudes of a moist, temperate climate, where there are long
seasons of alternate freezing and thawing, short hot summers,
and cold winters, must be of the most enduring kind. The well
preserved condition of the monuments of Rome and other cities
of the Mediterranean basin, after centuries of exposure, is not
due so much to the inherent qualities of the stone, as to the
warm, dry atmosphere. The obelisk of Luxor stood for cen-
turies in Egypt without being perceptibly affected by the climate,
but after only forty years of exposure in Paris it is now filled
with small cracks, and blanched. The same is true of the
obelisk in Central Park, New York, from which many pounds of
small fragments have fallen.

* (bid. 2 Did.

3A. A. JULIEN: Tenth Census, Vol. V, p. 370.

4J. C. Smock: Bulletin N. Y. Museum, Vol. II, No. 10, p. 385.

PTE ROPE RILES OME ULEDING STONES, £ TG. 173

The external forces of destruction may be conveniently con-
sidered in two classes: (1) those that produce changes through
mechanical disintegration and (2) those that produce changes
through chemical decomposition. In the case of disintegration the
adhesion between the particles or the cohesion of the particles
themselves is overcome, and the rock ultimately crumbles into
sand or powder. In the case of chemical changes the identity
of the mineral particles themselves is destroyed, by the minerals
being broken up into other compounds.

The following is a general classification of the agents of
mechanical disintegration and chemical decomposition:

I. AGENTS OF MECHANICAL DISINTEGRATION

A. TEMPERATURE CHANGES.
1. Unequal expansion and contraction of the rock and its mineral
constituents.
2. Expansion occasioned by the alternate freezing and thawing of
the interstitial water.
B. MercuanicaL ABRASION.
1. Water.
2. Wind.
Bo, SALE
GROWING ORGANISMS.
CARELESS METHODS OF WORKING AND HANDLING STONE.

oie

Il. AGENTS OF CHEMICAL DECOMPOSITION.

WATER-SOLVENT ACTION.
CARBON DIOXIDE.
SULPHUROUS ACIDS.

. ORGANIC ACIDS.

Temperature changes.—Injuries to a stone through changes in
temperature are occasioned in two ways: (1) By the unequal
expansion and contraction of the rock and its mineral con-
stituents, and (2) through expansion due to the alternate freez-
ing and thawing of the interstitial water.

GaAwW LS

174 SAO DITE SHO Re SIROLDLEAN TES)

Unequal expansion and contraction of the rock.—TYhe heat con-
ductivity of stone is very low. A stone a few inches in thickness
may be heated on one side to a temperature sufficiently high that
it will not bear handling, while on the other side the stone may
be comparatively cold. The actual expansion of different kinds
of stone has been experimentally determined by W. H. Bartlett,"
in which he obtained the following results:

Granite, .000004825 inch per foot for each degree F.
Marble, .000005668 inch per foot for each degree F.
Sandstone, .000009532 inch per foot for each degree F.

The diurnal changes in temperature in this latitude are often
as much as 50° F., while the annual variation in temperature
exceeds 150, F. A difierence of 150° F. would make a ditter
ence of one inch in a sheet of granite 100 feet in diameter.

Each mineral of which a stone is composed has a different
rate of expansion. Whenever a stone is heated each particle
presses against its neighbors with almost irresistible force.
When cooling begins, contraction sets in which initiates stresses
pulling the individuals apart. The inequalities in the rate of
expansion of the different mineral particles initiate stresses in
rocks having a heterogeneous composition, which tend to sepa-
rate the individual minerals from their neighbors. The result of
these alternating temperatures is to weaken the rock and produce
small cracks into which water may percolate or roots descend.

Besides the unequal expansion and contraction of the mineral
particles, there is an unequal expansion and contraction between
the different laminae or hypothetical layers of the rock which
are near enough to the surface to be affected by the atmospheric
temperatures. The layer at the surface suffers the greatest
change in temperature, and is therefore most affected. Each
succeding layer is less affected until a point is reached where
there is little or no change in the temperature the year around.
Owing to the rapid diurnal changes in temperature in some regions
forces are constantly at work tending to separate the superficial
stratum from those immediately below.

t American Journal of Science, Vol. XXII, 1832, p. 136.

TLE PROPER IME S VOL ROLE DING SRONES, ATC. 175

The igneous rocks on account of their heterogeneous min-
eralogical composition, interlocking character of the mineral
individuals, and difference in size, are more liable to injury from
the diurnal changes of temperature than are the unaltered sedi-
mentaries.

Investigation shows that, in arid regions, very great work is
accomplished simply through expansion and contraction due to
diurnal temperature changes. Merrill, in his ‘Rock Weather-
ing,” cites an instance in Montana where he found ‘‘along the
slopes and valley bottoms numerous fresh, concave, and convex
chips of andesitic rock, which were so abundant and widespread
as to be accounted for only by the diurnal temperature variations.
During the day the rocks became so highly heated as to become
uncomfortable to the touch, while at night the temperature fell
nearly to the freezing point.’’’
Hire Of Lock surfaces in’ Africa to rise as high as 137, FE. in the
day, and cool off so rapidly by night as to split off rocks

Livingstone reports the tempera-

weighing as much as 200 pounds. The expansive force of heat
is well shown in many of the limestone quarries in Wisconsin,
where beds from five to six inches in thickness are for the first
time exposed to the heat of a summer’s sun. These thin beds
become heated throughout their entire thickness and arch up
on the floor of the quarry, generally breaking and completely
destroying the stone.

Many buildings show the effect of weathering on the side
exposed to the direct rays of the sun, while the sheltered side
remains uninjured. The only rational explanation for this is
found in the diurnal temperature changes. Ordinarily the move-
ments due to temperature changes are necessarily small, but after
centuries of time they must invariably result in the weakening
and final disintegration of the stone.

Expansion occasioned by the alternate freezing and thawing of the
included water.—The effects of diurnal temperature changes as
described above, are smali when compared with the action of
continued freezing and thawing on a rock saturated with water.

™GEORGE P. MERRILL: Rocks, Rock Weathering, and Soils, p. 181.

176 STUDIES FOR STUDENTS

The expansive force of freezing water is graphically described
by Geikie ‘‘as being equal to the weight of a column of ice a
mile high, or little less than 150 tons to the square foot.”’ One
centimeter of water at 0° C. occupies 1.0908™ in the form of ice
at o° C. It is this expansion of about one tenth that does the
damage when confined water solidifies. .

Water finds its way into the rocks through openings or hollow
spaces which are everywhere present. Where the pores are
large the stone contains water of saturation which is given off
with comparative readiness, but the nearer the pores or sheet
cavities approach those of subcapillary size, the greater is the
tenacity with which the water is retained. One can readily
understand how the particles composing a rock may be so closely
fitted together, that the pores will be mainly of subcapillary
size. Such a rock will contain only the water of imbibition
which will be given off very slowly, on account of which the
attendant dangers from freezing will be increasingly great. In
general it may be said that the danger from freezing will be
increasingly great as the pores approach in size those of sub-
capillary dimensions.

Two rocks, one of which has very minute interstices and the
other of which has large pores may have a capacity to absorb
equal amounts of water. The former, however, will be in much
greater danger from alternate freezing and thawing. Of two
equally saturated rocks, one with 10 per cent. and the other
with 3 per cent. of pore space, in which the pores are of equal
size, the more porous one will be in greater danger of freezing.
The percentage of the pore space that is filled with water will
also condition the results of freezing. If two thirds of a rock is
saturated greater injury will result from its freezing than if only
one third were saturated. If none of the pores are more than
nine tenths filled with water, the effect of freezing will be noth-
ing, because the increased bulk of the frozen water will no more
than fill the spaces between the grains.

The amount of water contained in the pores at a given time
depends, of course, upon the amount of water initially absorbed,

LTE PROPER ES OF SULE DINGS LONES, LLC. WY

the time that has elapsed since absorption, the condition of the
atmosphere, the size of the pores, and the position of the stone.
It is only in exceptional cases that the stone in the wall of a
building is saturated. However, if the pores are of greater than
subcapillary size the water of saturation will, as a rule, be quickly
removed, except in the lower courses below the water line.

It would, therefore, appear that the most important factor in
estimating the danger from freezing and thawing, is the size
of the pore spaces, which controls the rate at which the interstitial
water is given up. The second factor of importance is the
amount of water contained in each of the pores at the time of
freezing. The third and last in importance is the total amount
of pore space.

1. S. Hunt, in “Chemical and Geological Essays,’ says:
“Other things being equal, it may properly be said that the
value of a stone for building purposes is inversely as its porosity
or absorbing power.” This statement has been quoted by vari-
ous authorities, one of whom says: ‘Other things being equal,
the more porous the stone the greater the danger from frost.”
The mistake has often been made of estimating the danger from
freezing by the capacity which a stone has to absorb water.
Likewise the capacities which two stones have to withstand
weathering are constantly being compared from the standpoint
of the ratios of absorption. Such estimates and comparisons are
very misleading, for one should not only know the capacity
which a stone has to absorb water, but he should, above all,
know and consider the relative size of the pores.

The injurious effects of the freezing of the ‘quarry water,”
as the interstitial water is called by quarrymen, has long since
been known to contractors, who generally refuse to accept stone,
especially sandstone, which has been exposed to the action of
freezing before being seasoned. Where it is possible, quarrymen
sometimes flood their quarry during the winter months, in order
to protect the stone immediately at the surface.

The openings formed along bedding, jointing and other fissile
planes, permit a freer circulation of water than the pores in the

178 SLODIES HOR STLODLENAGS:

rock. After an abundant fall of rain or when the snow melts in
the spring, the cracks, crevices and pores in the rocks cannot
carry away the water nearly as rapidly as it collects in these pas-
sages at or near the surface. If the temperature at such a time
is fluctuating between freezing and thawing, the water will be
alternating in a liquid and solid state. As the water congeals
again and again the walls are pressed farther and farther apart.
The ice acts as a wedge which automatically adjusts itself to the
size of the crack, until the opening is sufficiently wide and deep
to allow the free passage of the water. Not only are the cracks
and crevices very much enlarged and extended through the stres-
ses exerted by the solidification of the water but the stone is in
itself materially weakened.

The danger from the freezing of water collected along part-
ing planes must not be confused with the danger attendant upon
the freezing of water which fills the pores of the rock. The com-
pact, thoroughly homogenous rocks, without bedding or other
parting planes, whether sedimentary or igneous, are in less dan-
ger from alternate freezing and thawing than those in which
these structures occur.

Alternate freezing and thawing of the included water has
been one of the most potent causes for the decay of building
stone, more especially that stone which is bedded or otherwise
laminated. The most disastrous results occasionally occur from
using stone which has not been properly seasoned, and in cases
where the stone has been laid on edge instead of on the bed.
In the first case the stone is materially weakened throughout
by freezing, while in the latter exfoliation or scaling is liable to
ensue. The most trying place in a building, in which to place
a stone, is at the ‘‘ water line,’ where saturation is most common
and the greatest alternations of freezing and thawing occur. The

conditions are more severe in the case of bridge abutments and
retaining walls than elsewhere. In bridge abutments the courses
of stone at the level of the water are often badly shelled and
broken, while the stone above and below is scarcely injured. It
is not uncommon to observe all the courses of a retaining wall

THE PROPERIVES (OF BULLDING STONES, ETC. 179

in a dilapidated condition after it has been built a comparatively
few years. When the snow melts in the spring the water sinks
into the ground and issues through every crack and crevice in
the wall. As it collects along these fissile planes it freezes and
wedges apart the lamine of the rocks.

Because the sedimentary rocks more frequently have parting
planes than the igneous, they are as a class more apt to suffer
from alternate freezing and thawing. On the other hand the
sedimentary rocks are sometimes as free from parting planes as
the igneous, and are accordingly in as little, or even less, danger
from freezing.

The openings known as caves, caverns, and cavities need not
occupy our serious attention. Cavities occasionally occur in
both sedimentary and igneous rocks used as building stone, but
mainly in the former. They do not increase the danger from
freezing, owing to the fact that they are seldom filled with water
when near the surface. They weaken the rock slightly and often
occasion a roughness of the face when they occur at the surface.
The cavities are often partly filled with impurities, such as pyrite,
which may injure the rock, through the readiness with which
they decompose.

From the foregoing we may conclude that an ordinarily well
cemented sandstone, which is free from parting planes or strati-
fication, and in which the pores are of greater than subcapillary
size, is best suited to withstand alternate freezing and thawing
when placed in the wall of a building; assuming that the original
strength of the stone is sufficient for the position which it occu-
pies in the wall.

Mechanical abrasion —One of the most important agents of
disintegration in nature is mechanical abrasion, but the rdle
which it plays in the destruction of artificial structures is not
nearly as important as that of certain other agents.

Mechanical abrasion is accomplished mainly by wind, run-
ning water, and shuffling feet working in conjunction with the
other agents of disintegration. The beating of the rain against
the stone wall may overcome the adhesion between the rock

180 STUDIES FOR STUDENTS

particles, separate them from one another, and carry them
away. These particles may, in turn, as they are carried down
the side of the building, wear off other particles, and so on
until the bottom is reached. The effects of drifting sand,
that are such conspicuous features of the arid regions, are very
slight in the temperate zone in which we live. Drifting sand
contributes an almost insignificant part to the whole process of
disintegration. "J. C. Smock, in his report on the building stone
of New York, mentions the fact that the ground glass character
of many of the window panes in some of the older houses of
Nantucket are due to driven sand. The windward sides of many
of the monuments in the older eastern cemeteries have lost their
polish, while in some cases even the lettering has been destroyed
by this same agent. The monuments in the cemeteries of Wis-
consin which are located in sandy regions are beginning to show
the effects of wind-blown sand. The polish is dulled and the
lettering is becoming indistinct.

Besides being subject to the action of wind-blown sand and
rain, stone is often used in places where it is abraded by thou-
sands of feet passing over its surface. There is a great differ-
ence in the capacity which different stones possess to withstand
abrasion. Sidewalks, pavements, and steps may be seen in every
city which are more or less worn by constant shuffling of feet
over their surfaces.

Growing organisms.—It is a very common occurrence to find
lichens and alge covering the surface of a rock in a quarry.
Trees may also be observed sending their roots deep into the
crevices and cracks of the rock, and by their growth and expan-
sion huge blocks are often broken from the parent mass. In
some of the very soft rocks the writer has observed the finer
rootlets ramifying through the body of the rock itself, destroy-
ing the adhesion which bound the particles together. Decaying
plants are also known to give off organic acids which aid in the
decomposition of the rock. Fungi and alge often attach them-
selves to the stone, frequently almost entirely covering the
exposed surface. The most common form of plant growth

LAE PROPE ME SOL CLEDING SLONES, FETC: I8I

occurring thus is the lichen, which often covers the surface of
the rock after the manner of a mat, thereby exerting a protective
as well as a destructive influence. The covering which they form
serves as a protection against the atmosphere, while the acids inci-
dent upon their decay and the mechanical effects of their rootlets
penetrating between the grains are a slow cause of disintegra-
tion. Algz are also common, and often occur on the damp
parts of a wall, causing discoloration through their own decay
and the lodgment of fine dust particles. The effect of allowing
creeping vines, such as ivy, to cover the walls of buildings is
picturesque, but the practice is certainly injurious to the life of
the stone.

Careless methods of working and handliing.—The natural forces
of destruction have been greatly accelerated, either through the
ignorance of quarrymen and their total disregard for proper time
and methods of quarrying, or through the carelessness of workmen
in cutting, carving, and laying the stone used in building con-
struction. There are probably thousands of buildings, con-
structed out of stones, the lives of which have been shortened at
least one half by improper methods of quarrying and handling.

Quarrymen have been found moving stone with heavy charges
of powder, or even dynamite, expecting to obtain dimension
stone for building purposes. The heavy charges of powder not
only destroy a large amount of stone, but they also shatter the
cement and produce incipient joints in the blocks which may
accidentally remain in dimensions sufficiently large for building
purposes. The destruction of the cement and the production of
incipient joints not only weaken the rock, but also facilitate the
entrance of water, with the attendant dangers from freezing, with
which we are already familiar. This method of quarrying not
only materially lessens the value of the salable stone, but hun-
dreds of tons of otherwise marketable stone is absolutely
destroyed. The use of heavy hammers and sledges in split-
ting the stone, by striking continuously along one line, short-
ens the life of the stone in the same manner as_ heavy
blasting.

182 SIGIDMES, SHOU SIMGIQIEIN TSS

Much care should be exercised in quarrying stone in order to
prevent these unnecessary injuries. So far as practicable, quar-
rymen should take advantage of the natural joints. Whenever
blasting becomes necessary, the Knox system of small charges,
properly distributed, is reported to be the least injurious of any
method yet employed. The channeling machine, however, is
the best method of reducing the stone to dimensions that can be
easily handled. Especially in working sandstone and limestone
this machine can be employed to advantage.

The time of cutting and dressing stone may also influence
in a small way its life It is generally known that during the
process of seasoning the water which comes from within the rock
evaporates and deposits mineral matter which forms a crust on
the surface of the stone. This crust may be formed entirely by
‘tthe evaporation of the original interstitial water, or it may be
added to by water which has been soaked into the stone at a
later period and been subsequently brought to the surface.*
That water, which has been called the water of imbibition, proba-
bly carries a much larger percentage of mineral matter in solution
than the water of saturation. The water of imbibition is the last
of the quarry water to leave the stone, and therefore the crust is
not likely to be well formed until the rock has been thoroughly
seasoned. If the stone is to be seasoned before being placed
in the wall, it is advantageous to have it first cut, dressed, and
carved. Not only is it advantageous to observe this rule from
the standpoint of future durability, but also from the fact that
the stone often works much more readily when first quarried
thane ivudoes) alter jit has) beeni Seasoned ay Antena yenustmnias
once formed it should not be broken, because the softer rock
underneath, when exposed at the surface, will disintegrate much
more rapidly. For these reasons most stone should be worked
and finished, ready for laying in the wall, before it has been
thoroughly seasoned.

«The addition through saturation and evaporation after the quarry water has

been driven off is probably an almost unappreciable amount, depending upon the
amount of mineral matter originally in the water.

HE PROPERALES Of BULLDING STONES, ETC. 183

The manner of dressing a stone also influences in a small way
the length of its life. A stone which has polished surfaces sheds
water much more quickly and is disintegrated much more slowly
than one with rough surfaces. The stone with rough surfaces
has many crannies and crevices, in which the water collects and
is finally absorbed. Sandstone which has been hammer-dressed
is liable at first to disintegrate faster than that which has been
sawed, due to a weakening of the cement by the impact of the
hammer. In general, it may be said that polished and sawn
surfaces shed water most readily, while those that are rock-faced
or hammer-dressed, on account of their rough exterior, absorb
a considerably larger percentage of the water which falls on
their surfaces.

Before a stone is used in the construction of a building it is
safer to have at least the water of saturation driven off. Asa
rule quarrymen are acquainted with the effects of frost upon
stone in which the water of saturation still remains, and observe
the necessary precautions. There are quarrymen, however, inter-
ested solely in the disposition of their stock, who impose upon
the ignorance of the public by selling stone which has not been
seasoned. Stone should be seasoned not only to escape the
danger from freezing, but also to insure safety in handling and
laying.

The exfoliation of sandstone in the large eastern cities has
been mainly attributed to the fact that much of the stone has been
laid on edge instead of on the bed. Laying stone on edge has
been practiced at all times, owing to the greater readiness
with which stratified or schistose rocks can be dressed along
thewbed, The greatest tendency, to) lay stone on edge ‘is
encountered in veneer work, but is occasionally met with in
heavy masonry.

If the parting planes, which ordinarily furnish the easiest
paths for percolating waters, are normal or inclined to the sur-
face of the earth, they will admit the passage of water much
more readily than if they are parallel. Thus if a block of stone
is placed on edge in a wall, there will be greater danger from the

184 STUDIES FOR STUDENTS

freezing of the included water than if it were laid on the bed.
In case the stone is laid on edge, the pressure required to split
off lamina will ordinarily be much less than if the stone is laid
on the bed. In the first case the force occasioned by the freez-
ing of the water which collects between the layers is augmented
by the superincumbent pressure of the wall. If the stone is laid
on the bed, the water is less apt to penetrate along the parting
planes, and even though it should circulate with equal freedom
in this position, the superincumbent pressure of the wall would
tend to force the expansion in directions parallel to the bedding.

Furthermore, when stone is laid on edge the difference in tex-
ture of the various laminae are much more strikingly emphasized
than where the stone is laid on the bed. When laid on edge
the different blocks, as a whole, will exhibit different rates of
wear, instead of the minor inequalities ordinarily shown by the
different laminae when the block is laid on the bed.

In important structures one ought to avoid laying any stone
on edge which shows stratification or schistosity for the reason
that in this position it is inherently weaker and permits a more
ready absorption of water, with the attendant dangers from alter-
nate freezing and thawing.

AGENTS OF CHEMICAL DECOMPOSITION

In artificial stone constructions the decomposition of the min-
eral constituents of a rock proceeds much more slowly than dis-
integration. The forces which are at work breaking down the
chemical compounds have a much greater task to perform than
those which have simply to overcome adhesion and cohesion.

Water.—The active agent producing chemical changes in the
rock is water. Water generally contains in solution, besides
mineral salts, one or more acids, either sulphuric, sulphurous,
carbonic, or organic. Thus the water is often a very dilute acid
solution. As it percolates through the rocks it dissolves small
quantities of mineral matter in one place and deposits it in
another. Through these agents the minerals composing the rocks
of both the igneous and sedimentary series are decomposed, and
transfers of large quantities of mineral substances take place.

THE PROPERTIES OF BUILDING STONES, ETC. 185

In the case of building stone the chemical decomposition of
the minerals is so exceedingly slow that it seldom affects the
strength or life of the stone after it has been placed in a building.
Only in the case of limestone, dolomite, or marble, or where iron
sulphide or iron carbonate occur in other rocks, is any material
deterioration noticeable.

Sulphurous acids—In the case of decomposition of iron sul-
phide, in the presence of moisture, the formation of iron oxide is
the most conspicuous, although not the only result. The decom-
position of the sulphide produces sulphurous and sulphuric acids
which, in the case of dolomite, act upon the magnesium carbon-
ate, producing magnesium sulphate, which is often brought
to the surface and deposited as an efflorescence or incrust-
ation.

The sulphurous and sulphuric acid gases are mainly present
in the atmosphere of large cities where there is a large consump-
tion of bituminous coal. The action of these acids is largely
increased if the atmosphere contains a considerable amount of
moisture. In London, where fogs predominate and the con-
sumption of soft coal is very large, there seems to be little ques-
tion but that the effect of these gases is worthy of careful con-
sideration. But in the United States, with the exception of a few
of the larger cities, the influence of these agents is comparatively
small and needs but a passing mention.

Carbon dioxide —Wherever water heavily charged with car-
bonic acid gas is passed through calciferous rocks, more or less
of the calcium carbonate is dissolved, lessening the adhesion
between the different particles and weakening the rock. In
nature the results of this process are very great, but the carbon
dioxide has scarcely any appreciable affect on the durability of
stone in the walls of a building.

Organic acids.—The influence of organic acids resulting from
decaying organisms on the life and strength of a rock, especially
in the walls of buildings, is so slight as to barely warrant men-
tion.

12, IX, ISOC.

JE I TORIAL

THE meeting of the Committee on Rock Nomenclature,
appointed by the International Geological Congress, which was
held in Paris last October, failed to elicit concerted action on
the part of petrographers. Only two reports were received from
committees representing different countries. They were from
Russia and France, and will be transmitted to the Congress.
The small attendance at the meeting, the wide divergence of
views indicated by members expressing themselves by letter, and
the desire of independence manifested by all, make it impossi-
ble for the committee as a whole to transmit a report to the con-
gress. Each petrographer is expected to present his views in
his own way at the coming meeting in Paris.

Apparently there has been no progress toward harmony of
nomenclature or of rock classification. Phere is still a wide
divergence of ideas concerning rocks themselves and the methods
of dealing with them. While this is to be regretted, it is not to
be wondered at, considering the abstract petrological, as well as
the anthropic, elements involved in the problem. However,
there are indications of advancement along more or less con-
verging lines that will eventually unite. In the meantime every
petrographer is a law unto himself, as is evident from articles
recently published in this JouRNAL and elsewhere.

PROFESSOR Hosss, in his discussion of this subject in this
volume of the JourNAL, has laid special emphasis on the value of
diagrams in conveying ideas of relative quantities of chemical
constituents of rocks, availing himself of Brégger’s modification
of Michel-Lévy’s diagrams. The importance of such devices
for expressing relative quantities and for permitting ready com-
parison of many variable factors in an intricate problem cannot

186

EDITORIAL 187

be overestimated. They not only fix in an easily comprehended
form facts already vaguely apprehended, but often suggest rela-
tionships not previously suspected. With all machines the
product turned out depends on the material operated on. And
while the machine itself may be perfect, the product may be
open to criticism.

The diagrams in question tend to give more definite impres-
sions of the relative quantities of the chemical elements in rocks
than are obtained from the usual statements of analyses. But,
if instead of actual rock compositions there is substituted an
average of various rocks, it is clear that there is danger of
placing too much value on the apparently definite expression
conveyed by the composite diagram. Everything depends upon
what rocks have been grouped together. Defects in grouping
vitiate the diagram. For this reason it is desirable to distinguish
between the use of graphical methods of presenting an assem-
blage of diverse quantities, which is highly commendable, and
the practice of averaging diverse quantities, which is open to
serious criticism.

Joe Pails

ICSE WINES.

Om klimatets andringar 1 geologisk och slustorisk tid samt deras
orsaker. |On Changes of Climate in Geologic and Historic
Time and their Causes. | By Nits ExHoim, Ymer, Arg.
1899, H. 4, pp. 353-403. Published by Svenska Sallskapet
for anthropologi och geografi, Stockholm.

The first section of the paper discusses, in a general way, the causes
of telluric temperature changes. ‘The author states at the outset that
the temperature of the earth depends upon the ratio of the amounts
of insolation and radiation. He thinks that the solar radiation has
very likely not been subject to any considerable changes during the
time the earth has been an abode of life. But the transparency of the
atmosphere to different kinds of heat rays, and hence also to radiation,
has, no doubt, varied greatly and caused the great changes in climate
known to geology. Only in the second place would he put the eccen-
tricity of the earth’s orbit and the inclination of its axis as a cause of
climatic changes. He does not think that the eccentricity of the
earth’s orbit has caused any climatic variations which have left traces
known to geologists. But the variations in the inclination of the
earth’s axis have caused changes of considerable magnitude in the
polar regions, and in the adjacent zone, at least as far down as the
latitude of 55° in the northern hemisphere.

The old notion that the internal heat of the earth has appreciably
affected climatic conditions in geological time must be set aside. The
earth was, no doubt, at one time in the same condition in which we
now find the planet Jupiter. There was a dense atmosphere filled with
steam. After the temperature of this atmosphere of the cooling globe
sank below the boiling point of water its vapor rapidly (in a few hun-
dred years) condensed to a boiling sea. While the convection of this
sea was in effective action, the temperature of the sea bottom, the
upper crust of the earth, was rapidly lowered, which caused the outer
crust to crack open as it contracted relatively more rapidly than the
interior. This process went on until the radiation of the crust, outward

188

REVIEWS 189

(which grew less and less) equaled the conduction from below. Then
there was a resting time. The cracking ceased. Later thé conduction
of heat from the interior to the crust was smaller in amount than the
radiation from the surface. As a result lateral pressure was developed
and caused the rise of the land above the sea here and there in folds.

The paper then proceeds to offer proof that the conduction from
the heated interior is vanishingly small at present compared with inso-
lation, hence it can cause no appreciable rise in temperature now.

There follow some paragraphs on geological time and the probable
age of life on the earth. The author quotes some computations ‘made
by T. Mellard Reade and communicated by Chamberlin” relative to
the age of the sea (JOURNAL oF GrEoLoGy, Vol. VIII, p. 572). The
computations referred to were made by Chamberlin, though this is
not explicitly stated in the paper quoted. The estimates made by
Nathorst, Phillips, and Geikie are given. The calculations of Lord
Kelvin are also discussed. He is said to have made use of such
assumptions that the results attained can hardly be regarded as any-
thing more than a mathematical exercise without bearing on the phys-
ical problems involved. It is maintained that there are no physical
data disproving the high estimates of geological time favored by
geologists and biologists.

The headings of the third part of the paper may be rendered as
follows: Insolation nearly constant during geological time; changes
in the quantity of carbon dioxide in the atmosphere the principal
cause of the great climatic changes; the cause of the change in the
quantity of carbon dioxide in the atmosphere. The author refers to
Lord Kelvin as having made calculations on radiation from the sun,
and having reached the conclusion that the mean temperature of the
sun has been constantly rising. The author has carried out further
these computations in a paper just submitted to Kongliga Svenska
Vetenskaps Akademien, entitled Ueber den Energie-Vorrath, die Tem-
peratur und Strahlung der Weltkorper, and finds that the rise in the
mean temperature of the earth has been compensated by the diminu-
tion in the surface of the sun and also by the decreasing efficiency of
the convection currents from the interior to the exterior of the sun.
Possibly the radiation was less than it is now at the time when the sun’s
radius was sixty times its present length.

Then follows an account of the researches of Arrhenius. From
these some conclusions are drawn. It is estimated that a diminution

190 REVIEWS

of the carbonic acid in the atmosphere to two thirds of its present
amount would probably reduce the temperature of the polar regions by
5° C., and a tripling of the present amount would increase the tem-
perature there by 18° to 20° C., the temperature of the Cretaceous
period. A few paragraphs are devoted to discussing the amount of
carbon dioxide, the cause of its fluctuations. Using a commercial
simile, he remarks that the exchanges between the CO, consuming
processes and the CO, yielding processes are carried on with a very
small capital, and hence they are proportionately rapid, and as a result
are subject to great and fortuitous changes. New carbonic acid is
furnished by volcanic activities (Chamberlin, JouURNAL OF GEOLOGY,
Vol. VI, p. 611), and by meteors bringing it into the upper atmosphere.
Pursuing his commercial simile he remarks that the reserve fund is in
the sea. Chamberlin is again quoted on the effect of lime-secreting
organisms in the sea and as to the chemical condition of the carbonic
_ acid in the sea.

Over the first ocean the atmosphere very likely became, as time
went On, more and more impregnated with carbon dioxide. This is
supposed to have taken place after the conduction of heat from the
earth’s interior had ceased to have climatological importance. This
increase of carbon dioxide is believed to have resulted in the rise of
temperature which affected the crust of theearth. The temperature of
the early Cambrian age is hypothetically placed at 20° C., with a rise
during the period of 10° higher temperature. It is estimated that this
rise of temperature would cause folds four kilometers in height, if the
expansion were concentrated so as to have caused rising in any single
place. Ina similar way mountains are held to have been formed in
the Carboniferous age. By erosion large amounts of the carbonates
were carried to the sea, favoring the life of carbonate-secreting animals.
By the increase of land and of temperature the consumption of CO,
was increased, resulting in the withdrawal of much of it. Thus the
cold of the Permian age was brought on.

The progressive cooling of the surface temperature during the Per-
mian age is also discussed. A change from 30° to ro’ C. is assumed.
This brought about a contraction of the outer shell relative to the inner
kernel of the earth. The computed relative shrinking of the outer
shell is 12.8 kilometers. This shrinkage brought on extensive crack-
ing and volcanic activity, and thus led to an increased production of
carbon dioxide. Thus warm climate again resulted, probably lasting

REVIEWS 191

during the Cretaceous and into the Tertiary period. A subsequent
period of folding and withdrawal of carbonic acid resulted in the great
ice age. After several less well-known climatic changes—some geolo-
gists count as many as six different ice periods—the recent period
finally arrived with its temperate climate, in which we still live.

To the fundamental causes here discussed as affecting the climatic
changes of long duration, a secondary cause may be added, as pointed
out by Chamberlin, namely, the continued erosion and denudation of
the continents by precipitation. It is evident that this cause intensifies
the climatic conditions between ‘cold and warm periods. Ina note
(p. 375) the author leaves it to the future to decide whether the inter-
glacial periods are due to changes in the atmosphere, or to changes
in the inclination of the earth’s axis.

Since the cooling of the polar regions of the earth have, on the
whole, always been in advance of the cooling of the tropical and tem-
perate zones, our greatest mountains lie in these latter zones. The
polar caps have attained a greater solidity and resistance to pressure,
and thus the folding has been mostly transferred to other regions.

The sea has served as a great moderator of the climatic changes of
long period. Zhe cause of the latter must be sought in the alternate
contraction and expansion of the earth's crust following changes in the
mean temperature of the atmosphere.

The fourth part of the paper has for its subject che changes in the
inclination of the earth’s axts to the ecliptic and tts influence on climate.
Here is first given a summary of the evidence of changes in the
flora and fauna of northern Sweden, since the ice left the peninsula.
Since the time of the “‘Oak zone,” the average temperature has fallen
2° C., judging by the fossil distribution of Hazel. Possibly the winter
temperature was but little different from the present. Accepting the
archeologist’s figures as to the time of the appearance of paileolithic
man in Sweden, 7000 to 10,000 years back, the highest temperature of
the climate of Sweden seems to have occurred at that time. The
author then proceeds to show that the Quaternary changes of climate
can be readily and fully accounted for by the “long-periodic” changes
in the inclination of the earth’s axis. He has tabulated Stockwell’s
calculations (p. 381). These show the inclination to have been small
about gooo years ago, and that it has been increasing since then. He
presents a calculation of the length of the mid-summer day (the sun -
not setting) for Karesuando, the northernmost meteorological station

192 | REVIEWS

in Sweden, at the latest minimum and maximum of inclination, respec-
tively gtoo and 28,300 years ago, thus:

28,300 years ago - - 38 days
g,100 years ago - - - 62 days
At present 5 < = 54 days

Then follow tables showing calculated temperatures (in terms of excess
and deficiency compared with the present) for different latitudes dur-
ing the months of the year at the last maximum (28,300 years ago) and
the last minimum of inclination (g100 years ago) north of 80° N. lati-
tude. There was, 28,300 years ago, a deficiency of 5° C. In Sweden
the deficiency was from 3%° to 2° C. These figures are all for the
summer months. The author is uncertain as to the winter tempera-
tures. In Sweden these would perhaps depend on the gulf stream, as
at the present; g100 years ago the summer heat was 2° to 1.3° C. higher
than now, while the winter temperature is uncertain. A time with
hot summers occurred 48,000 years ago. Geologists know of no
other period of greater heat than the present, except the one gooo
years ago, sence the end of the last glaciation. ‘The end of the ice age,
hence, cannot have occurred earlier than 50,000 years ago. Possibly
it is later, but the greater summer insolation 48,000 years ago may have
helped in melting the ice.

The last section of the paper relates to climatological changes in
historic time, especially in northwest Europe. ‘Yhe author discusses
recorded observations on the forming and thawing of ice on various
Scandinavian waters, ancient stock-raising in Greenland, grape culture,
etc., and concludes that the winters have grown milder and the sum-’
mers cooler during the last 300 years. Some conclusions are drawn
from a study of weather records made by Tycho Brahe. A compara-
tive table of snow precipitation for Brahe’s time and the present is
given as follows.

PER CENT. OF DAYS WITH SNOW OUT OF TOTAL DAYS OF PRECIPITATION.

Years Oct. Nov. Dec. Jan. Feb. Mar, Apr.
1582-1597 (Time of Brahe) - 3 14 38. As 75 63 21
1881-1898 (Present) - ee 16 37 48 53 46 19

By comparing this table with current temperature, he finds that it is
likely that 300 years ago February was 1.4° C. colder than now, March
r° C. colder, and the other months differed either way by less than
2s

REVIEWS 193

Finally the author discusses secular temperature changes as indi-
cated by thermometric measurements made in the last roo or 150 years,
and concludes that at Haparanda, Stockholm, and Lund, in Sweden, the
January temperature has risen during this time 1° C., while that of
August has become somewhat cooler. At Lund, April, June, Septem-
ber, and October temperatures have remained unchanged.

The paper contains five figures. One of these shows the fossil
and present distribution of Hazel in Sweden.

This article is particularly interesting to one who has previously
read Chamberlin’s papers on the same questions. There are several
points of coincidence in the two. One of the authors is a meteor-
ologist, the other a geologist, by profession. On the main cause of
long-periodic changes of climate both agree. In accounting for minor
details the geologist favors meteorologic causes, while the meteor-
ologist seems inclined to accept, with a modification, a hypothesis
which has been quite generally favored among geologists.

J. A. UDDEN.

Sveriges temperaturforhallanden jamforda med det ofriga Europas.
[The Temperature Conditions of Sweden compared with
those of the rest of Europe.| By Nirs Exuorm, Ymer,
Arg. 1899, H. 3, pp. 221-242. Published by Svenska
Sallskapet for antropologi och geografi, Stockholm.

The only portion of this paper that has obvious geological bearing
is the statement that the temperature conditions of Sweden, especially
the cold winters which sometimes occur, are to be explained rather by
exceptional conditions favorable to radiation than by cold winds com-
ing from Siberia. The author shows, among other things, that the
recurrence of cold winters in Sweden exhibits a quite definite perio-
dicity of five and two thirds years, or half the length of the sun-spot
period. J. A. UDDEN.

Physiography of the Chattanooga District in Tennessee, Georgia, and
Alabama. By C. Witiarp Hayes. United States Geo-
logical Survey. Part VII, Annual Report, 1897-8.

In this report the author has done what Gilbert did in his ‘* Geol-
ogy of the Henry Mountains,” namely, has made a study of a region

194 REVIEWS

where the conditions are more or less simple, with a view of establish-
ing principles which may be used in regions of greater complexity.
The region concerned is situated in southeastern Tennessee, north-
eastern Alabama, and northwestern Georgia. It is bounded by the
meridians of 84° 30’ and 86°, and by parallels of 34° and 36°, and
comprises nearly 12,000 square miles.

The problems considered are as follows: (1) The forms assumed by
maturely adjusted streams in a region where the strata are faulted and
folded, and where metamorphism has so affected the rock that the
original differences have been diminished, leaving a somewhat homo-
geneous series; (2) the forms assumed by streams when the strata
- are practically horizontal, and where the beds vary greatly in hard-
ness; (3) the processes by which consequent drainage in a region of
folded strata is transformed into subsequent drainage, with the devel-
opment of anticlinal valleys and synclinal ridges; (4) the present alti-
tude of former base-levels and the determination of the deformations
which the region has suffered in recent geological time. These prob-
lems are considered under two main heads, namely, “‘Geomorphology ”
and ‘‘ Geomorphogeny.”’

The Chattanooga district embraces a part of each of the five natural
divisions into which the southern Appalachian province has been
divided by Powell." Within this region Hayes finds three types of
topography: (1) The Western type, including the Cumberland plateau
and the Highland Rim, a part of the interior low lands; (2) the Cen-
tral type, and (3) the Eastern type.

(1) The first or Western type is separated from the other divisions by
the Cumberland escarpment, which forms the eastern boundary of the
Cumberland plateau. In the northeastern portion of this district streams
have hardly begun to cut in the plateau, while to the south and west
only remnants of the plateau remain, each remnant retaining the char-
acteristics of the original highland. The plateau is about 1800 feet
above sea level, the Highland Rim about 1000 feet, while the low lands,
which stretch northwestward to the Ohio River, have an altitude of but
600 feet. Thus it is seen that the Highland Rim is a terrace between
the Cumberland plateau and the lowland. (2) The Central type is
that of the Great Valley, in which there are three levels or -sets of
levels. The valleys of the Tennessee and the Coosa rivers are from
600 to 700 feet above sea level. One series of valley ridges reaches

Physiographic regions of the United States: Nat. Geog. Mag., Monograph No. 3.

REVIEWS F 195

altitudes of from goo to rioo feet, and another altitudes of from 1500
to 1700 feet. (3) The Eastern type comprises the Unaka Mountains
and the western portion of the Piedmont Plain.

The formations of this region are divided into two groups: (1) The
unaltered sedimentaries which are of varying degrees of hardness and
solubility, and (2) the metamorphic and igneous rocks.

The twenty-three formations of the Paleozoic are divided into five
subgroups : (1) The lowest six Cambrian formations consist of con-
glomerates, quartzite, and siliceous shales, and are nearly insoluble.
These form the rocks of the Eastern division. (2) Ten Cambrian and
Silurian formations, composed for the most part of limestone and
shales, are relatively soluble. ‘These occupy the greater part of the
Valley or Central division, while a few beds of sandstone and the Knox
dolomite give rise to the valley ridges. (3) The Upper formations of
the Silurian and the formations of the Lower Carboniferous are the
rocks which form the Highland Rim, and also some of the valley
ridges. (4) On account of their solubility, the Lower Carboniferous
series gives rise to the characteristic topographic forms in the Western
division. (5) The durable Coal Measures conglomerates cap the Cum-
berland plateau and have occasioned the preservation of large areas of
its surface.

The second group of rocks, that is, the igneous-metamorphic
group, comprises, (1) the feldspathic (easily eroded) rocks which form
the larger part of the Piedmont plateau, and (2) the non-feldspathic
(resistant) rocks which have given rise to the irregular topography of
the Unakas.

In this region Hayes makes out three peneplains or base levels,
namely, the Cumberland base level, the Highland Rim base level,
and the Coosa base level.

The altitude of the reconstructed Cumberland base level at its
southern edge is about 1200 feet. From this altitude it increases to a
height of 2000 feet in the central part, and decreases again to 1600
feet along its southern and eastern edges. This gives a gradient of
ten feet per mile from the edges to the center, which is steeper than a
base level grade should be, and, besides, no base level tract should
have such a shape unless drainage radiated from its center, and this
does not seem to have been the case. Hayes explains the present form
by the hypothesis that in being elevated to its present position the
base leveled region was warped into the form of alow dome. Upon,

196 ; REVIEWS

the peneplain are a few remnants above the general level. The Cum-
berland base-leveling epoch came to an end with the uprising at the
end of the Cretaceous.

The Highland Rim is the peneplain next below the Cumberland.
It retains a very uniform height, the difference between the northern
and southern edges being but little more than existed during the period
in which it was base leveled. Upon this plateau also there are monad-
nocks which represent areas of more resistant rocks.

The altitude of the lowest and youngest peneplain is 700 feet at the
south and 800 feet at the northern edge. Here, as upon the other
plateaus, there are considerable variations in altitude in different parts
of the peneplain. ‘These should not be taken as indicating distinct
base levels, but simply the influence of local conditions. .

Hayes considers two hypotheses in explanation of these peneplains,
namely, subaérial denudation and marine denudation. He finds sup-
port for the former only.

The streams of this region belong to three distinct river systems,
the Cumberland, the Tennessee, and the Coosa. They are the main
agents which have shaped the present topography. There have been
periods of stability and relative inactivity, alternating with great revo-
lutions. It is hard to follow all these changes in detail, for the history
of each change is in some measure obscured by that of the next. The
first cycle of erosion resulted in the formation of the Cumberland
peneplain. This cycle began when the land was raised at the end of
the Carboniferous, and ended with the uplift closing the Cretaceous.
’ This long period of erosion was not a single cycle, but was composed
of a number of more or less distinct cycles, the evidence of which
remains even to this day. Hayes has worked out the general courses
of the Paleozoic streams in some detail, but no statement would be
intelligible without the maps.

When the Cumberland peneplain was raised and warped, and the
second cycle of erosion inaugurated, there were signs of activity all
along the line. The sluggish streams began again to cut their beds
and to fight for the mastery of favorable positions. The development
of new streams at the expense of the old, changes in the direction of
drainage, and final, almost perfect, adjustment of the streams in this
cycle are carefully worked out by the author. This second cycle, while
much shorter than the first, extends over a vast period of time. It
ended, as did the Cumberland, by a rise of the land and a slight

REVIEWS 197

warping of the surface. The streams again began to adjust themselves
to their new conditions, a work in which they are still engaged.

Hayes has made out the following changes which the streams have
gone through in reaching their present courses. First, they moved
westward to the interior sea as antecedent streams during the first cycle.
Then they were diverted southward to consequent courses, and at last
flowed westward as subsequent streams.

The way in which peneplains are correlated forms an interesting
section of the paper. ‘The types of stream basins as found in the region
are vividly described. ‘The maps, of which there are five, repay care-
ful study.

lay els tale (Ce

Geology of Minnesota, Final Report, Vol. IV. By N. H. WINcHELL,
U.S. Grant, WARREN UpHam, and H. V. WINCHELL. Quarto,
pp. i-xx, 1-630, with 31 geological maps, 48 photographic
plates, and 114 figures. St. Paul, 1899.

This volume, which completes the areal geology of the state, follows
its predecessors in the geographic arrangement of the subject-matter.
The area covered embraces the northern third of the state, and includes
some thirty counties and districts. The bed rock of the region, with
the exception of scattered patches of Cretaceous, is almost universally
crystalline in character, and is referred to the Archean and Taconic.
The thickness of the drift is very great throughout most of the region
considered, several counties in the northwestern part of the state pre-
senting no outcrops whatever of the bed rock.

The crystalline rocks in this largely new field have naturally
received much attention, resulting in the accumulation of a consider-
able mass of new facts relating to the Archean and Taconic, especially the
former. The interpretations based upon these facts differ considerably
from the commonly accepted views as to the character and divisions of
the ancient crystalline rocks, and especially as to the assumed repre-
sentative of the original crust of the earth.

It is to be regretted that the first presentation of a new classifica-
tion should be somewhat lacking in clearness, but nowhere in the
volume is there a satisfactory statement of the divisions into which
the various clastic and igneous rocks of the state have been separated,
nor of the equivalents in the ordinary classifications. As nearly as

198 REVIEWS

may be judged from the report, the classification of the pre-Silurian
rocks adopted by the survey is as follows:
Cambrian (St. Croix, ‘“‘ Potsdam”’)
(Upper Cambrian)
Rees (clastic)
and

Taconic
(Lower Cambrian) 4

{ Keweenawan Manitou (igneous)
oe (igneous)

Animikie

( eee ewan

Archean 5

Lower Kewatin

I. ARCHEAN

. Lower Kewatin.—The rock of the Lower Kewatin is in general
ae by the survey as greenstone, and is composed of two
divisions: (1) A lower massive igneous greenstone, assumed to repre-
sent the original crust of the seth, and (2) an upper series, partly
fragmental and partly chemical, including beds of basic tuff, of agglom-
erate, and of conglomerate, the jaspilytes and iron ores of the Ver-
million range, and vast masses of quartz-porphyry. Both the jaspilytes
and the porphyry are tentatively held to be the result of chemical pre-
cipitation in the Archean ocean, the apparent dikes of the porphyry
in the Upper Kewatin being considered as infolded masses, or as intru-
sions brought about by plasticity due to the subsequent application
of heat and pressure.

2. Upper Kewatin—The Upper Kewatin consists of a_ basal
(Ogishke) conglomerate, overlaid by a series of graywackes, argillytes,
and a single jaspilyte. The fragmental members are characterized by
the presence in greater or less amounts of greenish material supposed
to have been largely derived from the waste of the lower Kewatin,
and from the Archean volcanoes. ‘The whole series is involved with
the Lower Kewatin in vertical isoclinal folds.

All the members of the Kewatin, both Lower and Upper, have
been locally strongly metamorphosed, giving rise to clastic gneisses,
schists, etc., where the action was simply one of recrystallization, and

REVIEWS 199

to granites, syenites, diabase, gabbro, etc., where complete hydrothermal
fusion took place.

II. TACONIC

This is considered as the time equivalent of the Lower Cambrian,
and is separated from the Upper Kewatin by a marked unconformity.
It is separated into two divisions, the Animikie and the Keweenawan.

1. Animtkie.—The Animikie consists of a series of graywackes,
slates, and quartzites, and the Mesabi iron ore series. The beds vary
in dip from nearly horizontal to 45°. There are no known contem-
porary lava flows, but the rocks are characterized by the presence of
numerous sills and dikes of diabase intruded during the interval
separating the Animikie from the overlying clastics (Potsdam).

2. Keweenawan.—The clastic part of the Keweenawan is consid-
ered as Potsdam and is separated from the Animikie by a distinct
unconformity. It begins with a basal conglomerate, usually red in
color and of varying coarseness, known as the Puckwunge conglomer-
ate, and is followed by quartzites and sandstones interbedded with
lava flows of great volume and extent. The sedimentary beds became
progressively thicker as the igneous activities waned, finally terminating
in the white and siliceous sandstone of the overlying formation
(Upper Cambrian). The dip is even more gentle than in the
Animikie.

The eruptives of the Keweenawan are divided into two divisions,
the Cabotian and the Manitou.

(a) Cabotian.—The Cabotian includes the great masses of gabbro,
anorthosyte, diabase, etc., which in time of origin immediately ante-
date the Puckwunge conglomerate. In consequence of the great
extrusion of igneous material, designated as the “great gabbro revolu-
tion,’ large areas of the Animikie were covered with heated lavas,
resulting in the fusion of considerable portions of the former. Con-
temporary with this flow there were also important intrusions of
gabbro as sills and dikes in the unfused portions of the series.

(6) Manitou.—The Manitou series is made up of a great number
of surface flows, showing amygdaloidal and brecciated partings, and
alternating with beds of sandstone in the upper portion. The first of
the series appear as contemporaneous beds associated with the basal,
or Puckwunge conglomerate, but the greater part of the eruptives are
of a distinctly later date.

200 REVIEWS

III. CAMBRIAN

The eruptives of the Manitou series gradually cease and give place
to whiter and more siliceous sandstones, which in turn give way with-
out any general break to the magnesian and argillaceous limestones of
the Upper Cambrian. These Upper Cambrian rocks are of compara-
tively slight extent and importance in the area covered by the report.

Igneous rocks—The igneous rocks, both acid and basic, of the
Archean and Taconic are regarded as originating from the hydrother-
mal fusion of the older rocks, mostly from the clastics. The interme-
diate stages may often be seen.

The igneous rocks are of three classes— granites, diabases, and
quartz-porphyries. The granites are of three relative ages, two being
Archean and the third Taconic. ‘They are referred to the fused por-
tions of a still earlier acid clastic. The diabases are also of three
relative dates, in this case one being in the Archean and two in the
Taconic. They are believed to have been derived from the lowest green-
stones, or to occur as apophyses of the gabbro, itself a secondary condi-
tion of the greenstone. The quartz-porphyry dikes are again of three
periods, one each in the Lower and Upper Kewatin, and one cutting
portions of the Taconic. They are supposed to have been derived
from the great quartz-porphyry mass of the Lower Kewatin, or from
some later clastic.

Glacial Geology.— Besides the mass of observations relating to the
crystalline rocks, there are a considerable number relating to the
glacial geology of the northern portion of the state, but these observa-
tions are not systematically discussed with reference to the great
problems of glacial geology.

The thirty or more maps included in the report give, in addition
to the geology and ordinary topographic features, approximate con-
tours for every fifty feet, which adds greatly to their usefulness and value.
The maps are pleasingly colored and neatly executed. The volume is
profusely illustrated by photographic reproductions and line cuts.
The former, especially, are numerous, and though not always what
might be desired in the point of clearness and appropriateness, add
materially to the attractiveness and value of the report.

As one reads the report he cannot but be impressed by the great
number of observations made and the mass of facts accumulated, but
the disconnected and unsystematic manner of presentation, which
necessarily follows from the geographical treatment adhered to

REVIEWS 201

throughout the volume, detracts greatly from the value they would
otherwise possess. Too much is left to be inferred, and there is
always a strong liability of error in the putting together of scattered
observations from various localities which the reader is obliged to do
for himself in order to obtain an intelligent understanding of the
questions treated.

It is proposed in the next volume of the Final Report (Vol. V),
nearly half of which is already in type, to take up the systematic
geology of the state, and many of the details, upon which are based
the extensive changes of classification and the new conclusions regard-
ing the problems of archean geology, are reserved for publication in
this volume. It seems better, therefore, to reserve any extended criti-
cism of the proposed changes until the full facts upon which they are
based are published. M. L. FULLER.

The Ore Deposits of the United States and Canada. By JAMES
F. Kemp, New York, 1900, 3d edition, rewritten and enlarged.
xxiv-+ 481 pp. 163 illustrations.

It is with pleasure that geologists will welcome the new edition of
Professor Kemp’s work on ore deposits. It is to be noticed that the
revision has been so complete and the additions so numerous as to bring
the matter up to the date of publication and make it one of the most
valuable works of its kind in this country.

Professor Kemp has undertaken a difficult task in endeavoring to
embody in a single volume a serviceable text-book and a work of ref-
erence. That he has succeeded is shown in the first instance by its
increased use in the colleges and in the second by a perusal of its
pages.

The general plan of the work remains about the same as in the
former editions. The matter is divided into two parts, the first o
which treats of the general features of ore deposits, the underlying
geological principles, the minerals important as ores, the gangue
minerals, and their sources, the structural features of veins, the filling
of veins, and the classification of ore deposits. This part of the work
would have additional value, especially to the prospector and engineer,
if it were illustrated a little more fully by diagrams. It is true the
number of illustrations has been increased from. 94 to 163, but there is

202 REVIEWS

still room for more in the first part even though it should be at the
expense of some of the excellent half-tones in the second part.

Part II treats of the ore deposits in detail, taking up the metals
one by one, beginning with the more common useful metals, as iron,
copper, lead and zinc, followed by the precious metals, silver and gold,
and closing with the lesser metals. ‘The most important of these, iron
and gold, are treated more fully than the others and it is here we find
the greatest changes in the new edition. This portion consists largely
of a well arranged and classified review of the best literature on each
locality, all the more valuable to the investigator because specific ref-
erences to the original sources of information are given, thus making
it a handbook and manual of reference. Field studies and personal
observations in many of the leading mining centers have enabled the
author not only to present the most salient features, but to supplement
this from his own notes.

The features of the new edition that show the most marked changes
are as follows: (1) The Lake Superior iron district is completely revised
to accord with the enormous developments which have taken place;
(2) the part on limonite ores has been expanded; (3) the Butte
district has a new description and maps based on the excellent folio of
the United States Geological Survey; (4) the same is true of the
Cripple Creek and other districts in Colorado; (5) the part on the
gold deposits of the southeastern states has been rewritten and enlarged ;
(6) a description of the Canadian mining districts, which did not

appear in former editions, has been added.
Wo, Isle

The Fauna of the Chonopectus Sandstone at Burlington, lowa. By
Smee Wiican, IWiceins, Sie, ows Avcacl, Scrence, Woll, 2X,
No. 3, pp. 57-129. Plates I-IX. Feb. 1900.

In his series of Kinderhook faunal studies, of which the present
paper is the second,’ Mr. Weller is doing a much-needed work of
revision. The rocks now classed as Kinderhook mark the border line
between the Devonian and the Carboniferous over an important por-
tion of ‘the Mississippi valley. They were, by the earlier workers,
referred at times to both periods, and there was much dispute as to
their proper classification and correlation. Finally Meek and Worthen

1 For first see Trans. St. Louis Acad. Sci., I, No. 2., pp. 9-51.

REVIEWS 203

proposed the term Kinderhook to cover the beds, and named the
Burlington, lowa, section for one of the three type sections. ‘The best
known collection of fossils from Burlington has been that belonging
to the University of Michigan, and known commonly as the ‘“ White
collection.” Descriptions of the fossils in this have been published by
C. A. White, C. A. White and R. P. Whitfield, and by A. Winchell, and
these descriptions have been the ones principally used heretofore in
studying Kinderhook species. The descriptions were, however, in
many cases unsatisfactory, and were seriously limited in usefulness by
the fact that many of the species were not figured. Under the cir-
cumstances it is not surprising that the early doubts as to the age and
divisions of the Kinderhook have not been altogether cleared away.
Mr. Weller has made careful use of. the original White and other col-
lections, and has supplemented his data by notes and specimens taken
at Burlington. He has found that the Kinderhook includes seven
distinct faunal zones, and in the series of papers now being published
he is describing and figuring the fossils from these individual zones.
It proves that certain of them have strong Devonian affinities, while
others are to be assigned to the Carboniferous. Much of the confusion
has come from the failure to distinguish the individual bed from which
the species were collected. In the case of the Chonopectus sandstone the
brachiopods are, for the most part, strongly Carboniferous in aspect.
The pelecypods, gasteropods, and cephalopods, are predominantly
Devonian as is the larger number of the total of 81 species recognized.
The author regards this, however, as a probable instance of the persis-
tance into Carboniferous time of certain favored Devonian forms. The
other view, that these are the earliest and initiatory Carboniferous
forms appearing in time properly Devonian, is not, however, as yet,
excluded.

As a whole the paper is one of wide interest and value, and will

prove very suggestive and useful.
Isl, 183 15)

RECENT FUBLICATIONS

—Australian Institute of Mining Engineers, Proceedings of. Annual Meet-
ing, Melbourne, January 1goo.

—BAKER, FRANK C. Notes on a collection of Pleistocene Shells from
Milwaukee, Wis. Journal Cincinnati Society of Natural History, Vol.
XING INO, 5s

—CLEMENTS, J. MorRGAN and HENRY -LLOYD SmiTH. The Crystal Falls
Iron-Bearing District of Michigan with a Chapter on the Sturgeon River
Tongue, by William Shirley Bagley, and an introduction by Charles R.
Van Hise. Extract from the Nineteenth Annual Report of the U. S.
Geology Survey, 1897-8, Part III, Economic Geology. Washington,
1899.

—COMSTOCK, FRANK M. An example of Wave-Formed Cusp at Lake
George, New York. From the American Geologist, Vol. XXX, March
1900.

—Davis, W. M. The Fresh Water Tertiary Formations of the Rocky Moun-
tain Region. Proceedings of the American Academy of Arts and
Sciences, Vol. XXXV, No. 17, March 1900.

—DEAN, BASHFORD. The Devonian ‘Lamprey’ Palzospondylus Gunni,
Traquair, with Notes on the Systematic Arrangement of the Fish-Like
Vertebrates. Plate 1. Memoirs of the New York Academy of Sciences,
Vol. II, Part I, 1899.

—EKHOLM, NILS. Sveriges temperaturf6rhallanden jamforda med det 6friga
Europas. Stockholm, 1899.

Om klimates andringar i geologisk och hi storisk tid samt deras orsaker.
Stockholm, 1899.

—ForEL, F. A. Circulation-des eaux dans le glacier du Rhone. Academy
of Sciences, Paris.

—GRANT, U. S. A Possibly Driftless Area in Northeastern Minnesota.
American Geologist, Vol. XXIV, December 1899. Sketch of the Geol-
ogy of the Eastern End of the Mesabi Iron Range. From the
Engineers’ Year Book, University of Minnesota, pp. 49-62, 1898.

—GEIKIE, JAMES, Professor. A White-Hot Liquid Earth and Geological
Time. Reprinted from the Scottish Geographical Magazine for Feb-
ruary Igoo.

2.04

IOI OR eC EOLOGy

APRIL—MAY, rooo

EDWARD ORTON.

EpwaRD Orton, born Deposit, Delaware county, N. Y.,
March g, 1829, was descended from old New England stock on
both sides of the house. His father, Thomas Orton, a Presby-
terian clergyman, whose memory is still cherished in north-
Western News York, moved) to! Ripley; Ney) on: the lake
Erie shore soon after his son’s birth. There the son grew up
amid an agricultural population, sharing their work and their
amusements and gaining an intimate knowledge of their needs
which affected his whole course in life. Asa lad, he is said to
have been somewhat shrinking and sensitive to ridicule ; always
courteous, always considerate of the feelings of others and
sternly conscientious.

His father prepared him for college and, at what appears to
Hspthevearly age ot miteen,, he’ entered) the Sophomore year at
Hamilton with the class of 1848. The college course of fifty
years ago was narrow, carefully avoiding more than very super-
ficial treatment of the inductive sciences and dwelling chiefly
upon classics, elementary mathematics and certain philosophical
studies. Edward Orton pursued the course faithfully, though
there was little in it attractive to one of his tastes, and at gradua-
tion he had a well trained mind with a good stock of such
Wells WARK asos 3 205

206 JOHN J. STEVENSON

knowledge as the course afforded. The careful drill in linguistics
was that from which he derived most profit, and it was in evi-
dence throughout his writings.

After teaching; tor one year at rie; kas, hey entered aleane
Theological Seminary at Cincinnati, O., to prepare for the Pres-
byterian ministry, but, before the year ended, his eyesight failed
and he gave up study to become clerk on a coasting vessel sail-
ing to Florida. The autumn of 1851 found him in the Delaware
Literary Institute at Franklin, N. Y., where, as instructor in
Natural Sciences and German, he was expected to teach any
subject offered in the very liberal curriculum. The hours were
long and the classes numerous, but his enthusiasm infected the
pupils, who accompanied him on long field excursions for study
of botany and geology. The next year was spent at Harvard in
_ the study of chemistry and botany, after which another year was

spent in successful teaching at Franklin. He then entered
Andover Theological Seminary to complete preparation for the
ministry. He was licensed in 1855, and soon afterward was
ordained to act as pastor of the Presbyterian church at Downs-
ville, Delaware county, N. Y.

He resigned his charge in June 1856, to become professor of
Natural Sciences in the New York State Normal School at
Albany, N. Y. There he had access to the State Museum and
was associated intimately with the strong men on its staff. His
life in the Normal School was ideal, and his studies in the State
Museum were what he had longed for. Everything appeared to
be conspiring to his benefit and to great usefulness in his chosen
work.

But, early in his theological studies, doubts had arisen in his
mind respecting some tenets of the church and these, it is
believed, had something to do with the abrupt termination of his
studies at Lane seminary. These doubts were made stronger by
the surroundings at Harvard and he undertook the study at
Andover with an earnest desire to remove them. It contributed
to that result at least so far as to render them subordinate and
to permit him to assume the Presbyterian ministry. Atter he

EDWARD ORTON 207

went to Albany, however, the doubts returned and, increasing in
intensity, became convictions so strong that he could not con-
sent to remain in connection with his denomination. To avow
his opinions, which, being practically those of the Unitarian
church, were very unpopular at that time, would involve not only
separation from his church affiliations but also loss of his posi-
tion in the Normal School; for, though that was a state institu-
tion, a public discussion of his views might have alienated an
influential portion of the community if he had retained his chair.
To many men the temptation would have been serious; no
longer in the active ministry, he could have concealed his opin-
ions and could have withdrawn from his denomination without
discussion, in this way retaining his position, so important as
affording not merely support but also opportunity for thorough
study. But his sturdy integrity knew nothing of casuistry; he
could not be guilty of even negative hypocrisy. He avowed his
opinions, gave up his position, lost his income but gained the
abiding respect of his associates, both in church and in school.

The only opening immediately available was the principal-
ship of an academy at Chester, Orange county, N. Y., which he
accepted and held for six years, fitting young men for college
-and lecturing on scientific subjects whenever he had opportunity.
His duties left little of spare time, but what he had was utilized
in study of such natural phenomena as the region presented,
especially those connected with agricultural interests —an
admirable preparation for his future work.

Professor Orton’s intimate friend at Chester was the Rev.
Austin Craig, pastor of an independent church near that place.
In 1865, Mr. Craig was chosen acting president of Antioch
College in Yellow Springs, O., and Professor Orton was made
principal of the preparatory department. Soon afterwards he
was appointed to the chair of Natural Sciences. He proved
himself so wise, so tactful, that, in 1872, he was called to the
presidency of the college. But he was reluctant to assume the
responsibility and wrote to Dr. Newberry, with whom he was
associated on the State Geological Survey, asking advice. Ina

208 . JONAS SLEVEENSON,

manly way, without self-depreciation, he gave his reasons for
hesitation. Dr. Newberry’s emphatic reply was that a man’s
friends usually understand him better than he does himself.
The position was accepted and the event proved that his friends
were right. His administration was marked with such vigor, and
at the same time with such good judgment in dealing with men
both inside and outside of the college that he soon became
known throughout the state. When the State Agricultural Col-
lege was organized in 1873, he was made president, and pro-
fessor of geology.

' The organization of a state college with the agricultural land
grant as the endowment was a task whose magnitude might well
appal a thoughtful man. Local colleges dreaded a powerful
rival; farmers demanded a curriculum suited to their conception
of agriculture; lovers of the old methods of education feared
too much of application to everyday matters; ‘‘practical”’ men
insisted that little attention should be paid to theory, and that
‘‘practice’”’ should be supreme; politicians saw in the new insti-
tution an opportunity to strengthen themselves by grants of
positions; while not a few thought the gift from the national
government might prove to be another Pandora’s box. But
happily, the first board of trustees proved to be men of excel- .
lent common sense; they recognized that the work of organiza-
tion, if it were to be done well, would have to be done by one
familiar with educational needs, and that without interference.
The work was left to President Orton, whose studies of agri-
cultural conditions, carried on so assiduously for many years,
supplemented by his work as teacher, professor, and college
president, had rendered him familiar with the complex problems
involved. The curriculum was planned, not with a view to
bringing the greatest number of students at the earliest moment,
but with a view to the advantage of the state and of higher edu-
cation. The wisdom of this course was soon manifest, for,
though the number of students was small during the first year, it
increased so rapidly, and the scope of the institution was expanded
so greatly that in 1878 the name was changed to the Ohio State

EDWARD ORTON 209

University, the older title being recognized as no longer appli-
cable.

But executive duties were never attractive to him; they
interfered with his work asa student. Again and again he asked
to be relieved from the presidency, but not until 1881 did the
trustees feel that the institution could beara change. At that
time, when the university was established and its policy deter-
mined, they yielded to his urgent request. Thenceforward he
devoted himself to the chair of geology. With characteristic
wisdom he became merely a professor, and apparently forgot
that he had been president. One finds no room for surprise at
the respect and affection with which his colleagues regarded
him.

Professor Orton’s love for natural science was distinct early
in life, but it always leaned toward application to the benefit of
somebody, for, in the proper sense of the term, he was a utili-
tarian. As soon as he was settled at Yellow Springs he began
to study the deposits so well exposed in that neighborhood and
quickly gained, as no others had done, a thorough understand-
ing of their relations. His collections of fossils, made wisely
and scientifically, proved of great service to paleontologists; he
delivered lectures upon scientific subjects, accurate, yet devoid
of technical language—lectures of a type little known at that
time; he was sought as a speaker among farmers, in village
lyceums, and at teachers’ institutes. Within two or three years
he had become the scientific authority for southwestern Ohio.
When the geological survey was organized in 1869 he was
appointed one of the two assistants, with the southwestern por-
tion of the state as his district.

At that time there were few geologists. The old surveys
had ended in the early forties; a few attempts had been made
to organize new surveys, but only that in Illinois had attained
real success. Some students had gained experience on the gov-
ernment expeditions in the far West, but of trained geologists
there were barely a score. Professor Orton belonged to the
generation beginning work immediately after the Civil War, but

210 JOHN YR STEAVAIN SOM

he had done much more than most of those within reach, so that
his assistance was sought eagerly by Professor Newberry on the
Ohio survey. He began the investigation of the Silurians and
Devonian, which covered most of his district; but some of the
higher deposits were reached and he was compelled, under
instructions from the director of the survey, to pass beyond the
limits of his district and take up discussion of problems which
others thought were peculiarly their own. In all respects he
was the strong man of the corps. Painstaking and exact in
observation; scrupulous in statement; cautious in speculation,
he was called upon many times to render decisions in localities
respecting which the reports were in conflict. When Dr. New-
berry resigned after the publication of Volume III, Professor
Orton was placed in charge. The work was ina peculiar con-
dition. At the beginning of the survey the aids were mostly
young men with little field experience, this of necessity, as
trained geologists could not be obtained. Some of the work
done by those observers was very defective, as the writer, one of
the inexperienced aids, can testify ; county reports, written inde-
pendently, were not always accordant; even the general section
was unsatisfactory, for identifications had been made with hori-
zons in Pennsylvania beyond an area which had not been studied
in detail. Prior to Professor Orton’s appointment as director,
the work along the state line had been completed for the Pennsyl-
vania survey, and the results did not agree with those presented
in the Ohio reports. All this can be said without in any wise
reflecting upon those connected with the Ohio survey at the
beginning, for every man labored conscientiously to the best of
his ability, according to the knowledge then available. Their
work, though erroneous in some of the details, resulted in great
advantage to the state and in important contributions to
geology.

But Professor Orton, in taking up the matter anew, saw that
these errors, though apparently of slight economic importance,
might lead eventually to serious results, and he set himself to
correct them. How difficult the task was few can understand,

EDWARD ORTON 211

but the outcome was that masterly presentation of the whole
Carboniferous series of Ohio, in which. the relations and varia-
tions of every prominent bed as it occurs within the state and in
adjacent portions of other states are presented in such fashion
as to make the discussion distinctively one of the best yet con-
tributed to Appalachian geology. In this the awkward task of
correcting the errors of those who had made the original obser-
vations is performed with a delicacy rarely equaled. Good work
is noted, but errors are referred to in such a way that to discover
whose they are would require more labor than anyone would
choose to expend. Indeed, the reader is inclined to believe that
every error in observation was due to too earnest desire to do
faithful work—which is more than half true.

During Professor Orton’s term, the petroleum interests
attained great importance; the origin of the oil, the mode of
occurrence and the laws regulating the flow were studied with
great care. At the same time and with equal care problems
relating to natural gas were investigated. Professor Orton was
recognized quickly as an authority upon all matters respecting
petroleum and natural gas, whether scientific or technical, and
he was called upon by the Kentucky, New York, and United States
surveys to prepare elaborate reports; so that his writings will be
the standard reference for years to come. His studies led him
to issue appeals to the people of Ohio urging care in husbanding
their resources; but these were not received in the spirit in
which they were offered. He had the melancholy satisfaction of
seeing his forebodings justified by the event. The distribution
of fire and pottery clays, studied in reconnaissance by some aids
on the Newberry survey, was taken up systematically and a com-
plete investigation made under his direction by his son, who has
succeeded him as director of the survey. Building stone, iron ore,
glass sands, and other materials of economic interest, all received
careful study. Professor Orton’s reports prove the intimate
relation between pure science and industrial growth.

Throughout his career, while ever anxious to improve the
condition of the community by inducing men to utilize the dis-
coveries of geology, he was ever on the alert to advance the

BN 2 T OLIN MENS ILE VEEN SON:

cause of pure science; for he always maintained that only by its
rapid advance can the economic side find advance. The debt of
geology to Edward Orton is very great, far greater than we are
apt to think, for, in his writings, he effaced himself and often
gave credit to others for what was rightfully his own. While he
did much for science, he did even more for his. state, many of
whose industries owe the present success very largely to his
efforts—efforts due solely to his anxiety for the public welfare
and made without expectation of reward, pecuniary or otherwise.

But Professor Orton was more than teacher and geologist.
With burdens of exacting character in the university and in the
state geologist’s office, he found time and opportunity for serv-
ices in other directions. The city of Columbus lay near to his
heart and he was indefatigable in efforts to advance its interests.
He was always ready to aid in any organization looking to the
public good; even the state’s prisoners were objects of his care
for many years. He did not neglect his duties as a citizen, but
labored to secure proper candidates for political offices. His
time belonged to others; he never felt himself his own.

Professor Orton was always impressed with the exceeding
value of time, with the importance of utilizing moments. He
was as one intrusted with an estate to be improved to the last
degree before the owner’s return. Every day’s work was done
as though that were the only day. Such conscientious devotion
gave authority to his statements. Whenever his conclusions
proved to be erroneous, the error was regarded as merely addi-
tional proof of the limitations of the human mind. With this
spirit, whatever he did, whatever he wrote, was brought modestly
as a contribution to the growing edifice of knowledge and was
offered with such self-forgetfulness that recognition of its merit
and of indebtedness to him appeared often to be a matter of sur-
prise rather than of gratification. Honors came to him unex-
pectedly but they came often.

But while thus sensible of responsibility, Professor Orton
never carried a burden. He enjoyed the companionship of his
fellows; he had a keen sense of the humorous, but his humor
never took the form of sarcasm; no sting wasattached to any word

EDWARD ORTON Zils

that cropped from his lips or pen. Many times he was com-
pelled to assert himself forcibly, even indignantly, but no bitter-
ness could be discovered in his rebukes. He was the incarnation
of integrity ; a friend who never wavered.

Little wonder that when he died, the loss to science was less
regarded than was the personal loss which was felt by so many
in all stations and in all callings; that the man was remembered
more than a student. Those of us whose acquaintance with him
began thirty years ago became attached to him in such fashion
that we rejoiced when good came to him, not asking why it came
but gratified that it had come to so true a man. The man has
gone and now we think often of the student who deserved to
the full, and more, all of the recognition which his work received.
We can lay a double tribute upon his grave, one to the man
whom we loved and one to the geologist who solved so many
perplexing problems.

In the midst of his usefulness, in 1890, Professor Orton was
stricken by paralysis which rendered his left side useless. Crip-
pled, with his work incomplete, it seemed as though his life was
to pass away in darkness. But his mental powers were unaffected
and he recovered strength to such a degree that he continued to
work until within a short time previous to his death. In 1899
his health gradually declined. When the American Association
for the Advancement of Science met in Columbus last year, he
gave an address, so much longer and so much more important
than that expected from an incoming president, as to lead some
to suppose that he did not expect to live until the meeting of
this year. Be that as it may, the address was his last word to
his fellow-workers in science. He grew perceptibly weaker after
the meeting closed and, on October 16, 1899, he passed away
suddenly and without pain.

Professor Orton married, in 1855, Mary M. Jennings, of
Franklin, N. Y., who died in 1873. The four children of this
union still survive. He married Anna Torrey, of Milbury, Mass.,
in 1875, who, with their two children, survives him.

JoHN J. STEVENSON.

THE GRANITIC ROCKS OF THE PIKES PEAK
QUADRANGLE:

GENERAL RELATIONS

Frew natural features in the west are better known by name
and form than Pikes Peak, which has served so often as a goal
for the pioneer and traveler or as a fitting subject for the pho-
tographer and artist. Its prominence arises from its position as
the landmark first seen by the traveler moving westward, and
from the abruptness with which it rises 8000 feet above the
_ plateau at Colorado Springs.

Moreover, the rapid developments in mining at Cripple Creek
and the papers’ that have recently appeared on the subject have
increased the interest in the area and have directed thought to
its geology.

In the present paper it is proposed to give a summary of the
results obtained from a field and detailed laboratory study of the

t Published by permission of the Director of the U. S. Geological Survey.

The field work for the present paper was carried on by the writer while a field
assistant in the party of Mr. Whitman Cross who directed the work and suggested the
probiems to be studied. Many of the specimens were collected by Mr. Cross, and his
field notes have been used freely. For the constant willingness to give assistance
and the freedom in the use of notes, the writer wishes to express his gratitude to Mr.
Cross, who furnished the opportunity to study so extensive an area.

2 WHITMAN Cross: Intrusive Sandstone Dikes in Granite, Bull. Geol. Soc. of
Am., Vol. V., 1894, pp. 225-230; Geology of the Cripple Creek Gold Mining Dis-
trict; Proc. Colo. Sci. Soc., June 4, 1894.

R. A. F. PENROSE, JR.: The Ore Deposits of Cripple Creek, Colo. Jdzd.

E. B. MATHEWS: The Granites of the Pikes Peak Area, Bull. Geol. Soc of Am.,
Vol. VI, 1894, pp. 471-473.

WHITMAN Cross and R. A. F. PENROSE, JR.: Geology and Mining Industries of
the Cripple Creek District, Colo. Part I, General Geology, WHITMAN Cross; Part
II, Mining Geology, R. A. F. PENROSE, JR. Sixteenth Ann. Rept. Dir. U.S. Geol.
Sury., Il, Washington, 1895, pp. 13-217.

W. O. Crosspy: The Great Fault and accompanying Sandstone Dikes of Ute
Pass, Colorado, Science, new series, Vol. V, 1897, pp. 604-607. Archean Cambrian
Contact near Manitou, Colorado, Bull. Geol. Soc. of Am., Vol. X, 1899, pp. 141-164.

214

GRANITIC ROCKS OF PIKES PEAK QUADRANGLE 215

granular igneous rocks comprising the summit of Pikes Peak,
and the area to the west of it, included within the Pikes Peak
quadrangle of the Geologic Atlas of the United States. The
field observations were made during the seasons of 1893 and
1894, and the laboratory studies during the succeeding winters.

The quadrangle studied contains, approximately, 930 square
miles and embraces the greater portion of the southern termina-

Fic. 1.—Pikes Peak seen from the plain.

tion of the Front or Colorado range in its en eschelon enaing east
of the Royal Gorge of the Arkansas. The topographic features
of the area are the mountain massif on the east, rising rapidly as
shown in Fig. 1, from the level of the plateau to the height of
14,108 feet above the sea. Westward from the summit the slope
is much gentler, as shown in Fig. 2, to the somewhat dissected
plateau of Cripple Creek and Florissant, drained on the north by
the tributaries of the South Platte River and on the south by Oil
Creek and its tributaries which drain into the Arkansas River
The divide between these two drainages does not include the
summit of Pikes Peak but passes somewhat to the north and
west of the mountain mass.

Bild EDWARD B. MATHEWS

The rocks of the region represent massive and schistose
granites, metamorphic schists, remnants of formations belonging
to the Algonkian, Cambrian, Silurian, Carboniferous, Jura-trias,
Cretaceous, and Eocene periods, and numerous igneous rocks
including basic breccias, massive andesite, andesite breccias, tra-
chyte, rhyolite, phonolite, and nepheline-syenite.

The granites and gneisses of the Rocky Mountains have gen-

Fic. 2.—Pikes Peak from carriage road (13,000), (showing gentler western slope).

erally been regarded as part of the Archean complex, but it has
been shown" that within the main granitic masses of the Pikes
Peak area there are many included fragments of quartzite and of
schists that show their derivation from sandstones through indu-
ration and metamorphism. These sediments are regarded as of
Algonkian age, and the granites cutting these strata are accord-
ingly either Algonkian or early Cambrian. It is deemed most
in harmony with the facts in the case to refer the granitic erup-
tions to the late Algonkian period.

The schistosity in the gneisses was produced prior to the
Upper Cambrian and this fact, together with the assumed age of
the granitic eruptions renders it probable that the squeezing

t Pikes Peak Folio No. 7, Washington, 1895.

GRANITIC ROCKS OF PIKES PEAK QUADRANGLE 217

of the granites is due to earth movements which preceded the
Cambrian.
The following pages treat almost exclusively of the granitic
rocks of the area.
ROCK TYPES

The greater portion of the area studied, as shown by the
accompanying sketch and the more complete map in the folio of
the Geologic Atlas, is occupied by granites, gneisses, and asso-
ciated schistose rocks which form an undulating platform under-
lying the later formations. The prevailing composition of this
complex is that of a typical granite with the addition of a small
amount of fluorine, while the characteristic mineral constituents
remain the same over an area of more than a thousand square
miles, notwithstanding the fact that the exposures are represent-
ative of bodies intruded at different periods, and crystallized
under somewhat different conditions. The granites are light col-
ored, usually pinkish, holocrystalline aggregates of feldspar,
quartz and biotite with occasional hornblende and flucrite. The
individual components vary in their size and relative abundance
and in the perfection of their crystal form ; but in almost every
instance the feldspar is larger, more abundant and somewhat bet-
ter formed than either the quartz or biotite. These variations
in the manner of aggregation and in the size of the constituent
minerals give rise to well-defined types of granite which were
distinguished and plotted in the field.

Although some sixteen varieties of granite were distinguished
during the mapping, later study has shown that all masses of
prominence may be referred to one of four clearly defined types
which have been named,’ the Pikes Peak, the Summit, the Crip-
ple Creek, and the Fine-grained types respectively.

PIKES PEAK TYPE
A large part of the area of the accompanying map is occupied
by a single type of granite, called the Pikes Peak type, from its

* Geological sheet. Pikes Peak folio, No. 7, Washington, 1895.
2 Bull. Geol. Soc. Am., VI, 1894, pp. 471-473.

218 EDWARD B. MATHEWS

prominence in the constitution of the Pikes Peak massif. This
type is characterized by the relatively large size of its feldspar
and quartz grains and its tendency to form conspicuous feldspar
phenocrysts that often attain a diameter of several] inches.

The fresh, unaltered granites of this type are coarse-grained
aggregates of quartz, perthitic feldspars, and biotite with occa-

Fic. 3.—Pikes Peak type of the granite.

sional accessory hornblende or fluorite and microscopic apatite,
zircon, titanite, magnetite, rutile, hematite, limonite, epidote, and
allanite.

The grain varies widely from extremely coarse where the
feldspar phenocrysts are six inches long to the more normal
granite in which the length of the feldspar grains is little more
than a quarter of an inch. The usual diameter for the feldspar
is about half an inch, and for the quartz, a quarter of an inch to
an eighth of an inch. The biotite areas, although generally
smaller than the quartz grains, are sometimes a half inch in
width. (Fig. 3.)

GRANTITIC ROCKS OF PIKES PEAK QUADRANGLE 219

The texture of this type presents all grades of transition from
that in which the feldspar is only slightly larger than the quartz
to one in which the feldspar stands out in large, imperfectly
formed porphyritic crystals."

The areal distribution of the rocks showing such increase’
in the development of the feldspar is not clearly defined, although
there is a faint suggestion of a concentric wrapping about the
lower slopes of Pikes Peak.

A mechanical separation shows the constituent minerals of
the Pikes Peak type to be in the following proportions by weight:

Quartz - - - - = Bail
Microcline - - - - 53-3
SBOE a s— - - - = 1x4
Oligoclase - - - - 2.6

100.00

The ‘biotite’ includes all of the minerals with a greater
specific gravity than 3.0.

The quartz occurs in large irregular or oval, colorless or
smoky grains distinctly outlined against the feldspar and biotite
towards which it is usually xenomorphic. In one instance, a
basal section of quartz presented three systems of cracks inter-
secting at 60° representing an imperfect rhombohedral cleavage
probably due to mechanical deformation. The extinction ranges
from completely simultaneous to mottled or undulatory.

The inclusions observed are arranged according to one of
three ways. (1).The small and irregularly shaped inclusions
occur either in long thin lines parallel to the rhombohedron, in
broader unoriented zones, or irregularly massed in definite parts
of the quartz individuals. (2) The small, somewhat rectangu-
lar cavities are arranged in indistinct lines parallel to their longer
directions but not related to the crystallographic directions of
the quartz. (3) The fine, hair-like ‘‘ needles” have a linear
arrangement and seem to occur when the other inclusions are

*The coarse-grained granite in which the feldspar phenocrysts are large and
generally well formed, is sometimes called the “‘ Raspberry Mountain granite,” from its
conspicuous development on that mountain.

220 EDWARD B. MATHEWS

fewer and more evenly disseminated through the quartz. The
mineral nature of the last group could not be determined. The’
individual inclusions are minute apatites and zircons, hematite
plates and magnetite.

Quartz occurs in some of the slides as an inclusion in the
feldspars. It is probably secondary in both the microcline and
the oligoclase, though in the former it may possibly be original.
With the feldspar quartz forms micropegmatitic intergrowths in
the more weathered and crushed specimens, but this is lacking
in the fresh, unaltered rocks.

The feldspars in the Pikes Peak type vary in size, shape, com-
position, and age. The color is generally pink or gray, or both
where there is a zonal structure. The most important feldspar
is microcline perthitically intergrown with albite. This always
shows the characteristic ‘‘ microcline twinning” in all sections
inclined to the brachypinacoid. The mesh of the rectangular
grating is very small in all those instances which are regarded as
original. In the small secondary flakes, however, the mesh is
much coarser.

The inclusions within the microcline are albite, quartz, oligo-
clase, biotite, and the earlier products of crystallization. The
most abundant are perthitic pegs of albite, and their disk-lke
cross-sections. The former lie approximately parallel to a steep
positive macrodome in a plane normal to the edge (001) (010).
The small round disks may easily be confused with the pellucid
quartz from which they can be separated only by the use of con-
verged polarized light. i‘

Oligoclase is only of subordinate importance in the Pikes Peak
type where it occurs in small light gray-green anhedral areas
with characteristic polysynthetic twinning, lamellae showing on
the base an extinction angle of 2°—3°. The inclusions lie close
together near the center of the plagioclase plate and are sur-
rounded by a zone of clear feldspar from which they are more
or less sharply defined. The cause of the presence and position
of these inclusions is not known. The usual explanation based
on the increased basicity and consequent instability of the core

GRANITIC ROCKS OF PIKES PEAK QUADRANGLE 221

may apply, but the same phenomena may be the result of varia-
tions in the conditions during solidification. With the less vis-
cous state of the magma during the early stages of solidification
the supply of material is abundant and the growth rapid. The
imperfections in crystallization increase with the rate of consoli-
dation, through the inclusion of interpositions and the imperfect
filling of space. As the magma on cooling becomes more vis-
cous, thereby decreasing the easy transfer of material and the
consequent rate of growth, the molecular arrangement of acquired
material on the growing crystal is more perfect in its outer zone.
This difference in homogeneity between the core and exterior is
sufficient to develop a tendency towards molecular rearrange-
ment in the interior whenever the physical conditions are
changed. The sharpness of the limits is determined by the
growth lines as in twinning lamellae or zonal structures.

Biotite occurs either as individual flakes or small aggregates
presenting the appearance of single flakes to the unaided eye.
The mica is strongly pleochroic in brown and yellow, and has
an optic angle of 10° Since the plane of the optic axes was
found in several instances to lie perpendicular to the leading
ray of the percussion figure, much of the mica is probably
anomite.

Hornblende is relatively rare in all the granites of the area.
It occurs most often in the Pikes Peak type associated with
biotite and titanite. The amount of mica decreases somewhat
when hornblende is present, while an increase in the latter is
generally accompanied by an increase in the titanite. The horn-
blende-bearing granites occur in somewhat circumscribed areas
below Green Mountain Falls, along the railroad east of Florissant
and in the hills east of Lake George.

The accessory minerals enumerated on a preceding page
occur in varying amounts. They are usually in small crystals,
and belong to the earlier stages of consolidation. Titanite and
fluorite are of especial interest, since the former has been found
only in this type while the latter is rare, though abundant in the
Summit type. Neither presents any mineralogical peculiarities.

PD PD EDWARD B. MATHEWS

Among the alteration minerals resulting from the weather-
ing or metamorphism of this type are epidote and sericite
associated with the feldspar; and calcite, chlorite, and muscovite

accompanying the biotite.

47,

SS
N
S

S
X

S

CE OO
a,
x

77
LZ

N NN 5 VV 7
SS Ef 27 ea
Pikes Peak Summit Cripple Creek Gneissic Postgranitic

Fic. 4.—Sketch map showing the distribution of the various types of granite
occurring in the Pikes Peak quadrangle.

Distribution.—The granites of this type extend northeastward
from a sinuous line drawn through the lower slopes of Blue
Mountain, Dome Rock, Cripple Creek, and Oil Creek Canyon to
the southeastern border of the Pikes Peak Quadrangle. (Fig. 4)
The limits beyond the area of the Quadrangle have not been

GRAWNITIC ROCKS OF PIKES PEAK QUADRANGLE 223

examined, but are shown in a general way in the maps of the
early Hayden survey some miles to the north and east of the
Pikes Peak area. Similar rocks have been described from the
Platte Canyon in Jefferson county for the Educational Series of
the United States Geological Survey."

In its distribution the Pikes Peak type, in the contact with
each of the three remaining types distinguished, appears as the
older type. It is therefore the oldest granite in the area. The
best place for studying the age of this type is in the region
about the summit of the massif. Here it is cut by many dikes
of the Summit type, which seem to radiate from the central
eminence. The actual contact between the two granites is rarely
evident in this area, however, as the blocks of the Summit type
have formed a slide slope which masks the more easily dis-
integrating coarse-grained granite. Wherever the contact is
observable, as in Wilson Creek southeast of Cripple Creek, the
finer rock is seen to cut the coarser. The relations with the
Cripple Creek type are poorly defined, as the exposures almost
always show small masses of metamorphosed sediments at the
immediate contact. The, greater age of the Pikes Peak type ts
shown, however, in several exposures, as, for example, on the
north side of Caylor Gulch at an elevation of 8600 feet, where
a fine-grained saccharoidal granite of the Cripple Creek type
cuts the coarser schistose granite which is correlated with that
onthe Pikes) Peak type.

Weathering.—The processes and results of weathering in the
Pikes Peak type are among its most characteristic features. The
light pink color becomes darker on exposure and passes into a
deep red through a bleaching of the biotite and the subsequent
staining of the feldspars and quartz with the liberated iron oxide.
The physical changes due to weathering are, however, more
manifest. The rock disintegrates before it is decomposed. For
this reason the hills are rounded and covered with granite gravel
when the disintegrated material remains, and rugged or steep
where the débris has been carried away. Fig. 2 gives a view of

t Bull. U.S. Geol. Surv., No. 150, Washington, 1898, pp. 172-177.

224 é EDWARD B. MATHEWS

Pikes Peak from the northwest at an elevation of 13,000 feet,
which well illustrates this difference. On the west the mountain
slopes with smooth rounded outline into the drainage of Beaver
Creek, while on the east the descent is precipitous in ragged
cliffs, sometimes resembling huge cyclopean masonry. Counter-
acting this physical disintegration are chemical changes which

Fic. 5.—Disintegrated bowlder of granite showing surface hardening and dis-
integration beneath. 4

protect the rock at first, but ultimately, in conjunction with the
physical forces, accelerate the rate of rock-weathering.

The effect of weathering extends for a distance of two or
three feet beneath the surface of the exposed rocks. On the
exterior there is frequently a dense crust, or glazing, rarely
more than half an inch thick, covering a second zone several
inches wide, in which the mineral are stained with iron and
loosely held together. Beneath this zone the rock is often so
incoherent that it seems ready to fall to pieces. The crumbling
mass, in turn, passes gradually into the solid rock. Fig. 5 repre-
sents a bowlder with the coating on the surface and the disinte-
grating rock beneath. In this view the upper surface appears

GRANITIC ROCKS OF PIKES PEAK QUADRANGLE 225

more resistant to the weathering agencies, while the friable rock
beneath has fallen away leaving the crust as a projecting edge.
Such a crusting over friable material often leads to fantastic
shapes, as represented in Fig. 6. The final result of the weather-
ing is the formation of a thick coating of talus and granite gravel,
composed of relatively fresh fragments of the rock and _ its
mineral constituents. .

Fic. 6.—Fantastic forms due to weathering and surface hardening.

SUMMIT TYPE

The rocks of the Summit type show a very constant texture
closely allied to that of granite-porphyry (Fig. 7). They are
composed essentially of small gray feldspar phenocrysts embed-
ded in a finely granular aggregate of hypidiomorphic, quartz,
smaller feldspars, biotites, and minute grains of fluorite.
Microscopic zircon, magnetite, hematite, and micropegmatitic
intergrowths of quartz and feldspar are also present.

When fresh the color of the rock is purple, ranging from pur-
ple-violet to carmine-purple.t As the rock becomes weathered
the color becomes’ less pronounced and fades to light neutral
gray and brown. |

The minerals composing the Summit type differ very slightly
from those described under the preceding type. Quartz is more

*Nos. 23, and 26; of Radde’s International Farben scala.

226 EDWARD B. MATHEWS

abundant and in smaller areas, and the numerous fine grains in
the groundmass are free from much included matter. The
larger individuals, however, present the broad zones of inclusions
noticed in the preceding type. The porphyritic feldspar is
microcline, as in the first INOS, IW: InEre ae perthitic inter-
growths of albite are much less common. The microcline also

Fic. 7.—Summit type fine grained granite-porphyry.
composes much of the groundmass where it fills the interstices
between the grains of quartz. Untwinned clear grains of feld-
spar, probably orthoclase, are also present in the groundmass in
considerable abundance. Oligoclase showing fine twinning
lamellae is more poorly developed than in the Pikes Peak type.
All of the feldspars are much clouded with alteration products,
especially by sericite and some iron compound, either hematite or
limonite. The abundant development of micropegmatitic inter-
growths of quartz and microcline in this type is noteworthy, as
these are practically wanting in the fresh Pikes Peak granite. The

GRANTTIG ROCKS OR PIIGES PEAK QUADRANGLE, 227

quartz occurs in small oval, or irregular, disks which have the same
orientation over considerable areas of the feldspar. Although these
disks may lengthen out, they do not have the branching-radial
arrangement characteristic of some of the other occurrences.

The biotite occurs in flakes without good crystal outline, and
locally shows quite an advanced stage in the alteration towards
chlorite and lenses of quartz formed between the foliae. The
same slide may show perfectly fresh pieces of biotite associated
with that which has become thoroughly chloritized. Unlike the
mica of the Pikes Peak granite, the biotite of the Summit type
is of the first order with the plane of the optic axes parallel to
the principal ray of the percussion figure.

Hornblende, titanite, and magnetite are practically wanting
in this type, although a few fresh irregular grains of the latter
were noticed in a single slide.

The most characteristic mineral in the Summit type is fluorite.
This is present in every section but one made from the Summit
granites. It is commonly in small irregular areas and rarely in
well-defined crystals. When the crystal contours are evident
the little squares suggest either cubes or octahedrons. The min-
eral is especially characterized by a highly perfect octahedral
cleavage which is well developed in the larger areas, but is
lacking in the minute crystals. The anhedral areas are clear
and either colorless, purple, faintly pink, or green. The pigment
is unevenly disseminated through the grains, and seems to be
more intense about inclusions than in the clearer parts of the
mineral. Between crossed nicols the areas remain perfectly
isotropic, and in ordinary light the mineral shows a shagreened
surface corresponding to its very low index of refraction. All of
the properties enumerated are characteristic of fluorite. The
view that this is fluorite is corroborated by the high percent-
age of fluorine in the bulk analyses and the presence of fluo-
rides in the veins of adjacent areas.t Microchemical tests were
made, but failed to give conclusive results.

*E.g., St. Peter’s Dome (Bull. U. S. Geol. Sury., No. 20), and Cripple Creek
(Sixteenth Ann. Rept. U. S. Geol. Surv., II, 1895).

228 EDWARD B. MATHEWS

Although the gold ores and the fluorite are sometimes inti-
mately associated in the mining area near Cripple Creek, no indi-
cations of gold, sulphides, or tellurides were seen in any of the
sections of the Summit type.

Distribution.—TVhe rocks of the Summit type are confined to
a small area about the Summit and down the western slope of
the highest part of Pikes Peak, and the relation between them
and the other granites is only seen in a few places. On the main
peak there seems to be a system of radiating dikes, but the con-
tacts are not well exposed in place. In Wilson Creek canyon
and near the intersection of Spring Creek with the Cripple
Creek-Florissant road there are dikes of granites correlated with
that of the Summit type which clearly cut the older Pikes Peak
granite.

Towards the other granites this type seems to be older, since
it is never found in them, while they occur in small masses within
its areas.

Weathering —In the manner of their weathering the rocks of
the Summit type show many differences from those of the Pikes
Peak type. Instead of disintegrating into massive, rounded
bowlders and coarse gravels like the latter, the granite-porphyry
breaks up into smaller angular blocks, as illustrated in the
familiar views of the Upper Station of the Pikes Peak Railway.
These blocks and many of the ledge exposures, moreover, have
a glazed crust similar to that observed on bowlders of the Pikes
Peak type. What the nature of the process is which produces this
surface was not determined in the somewhat hasty survey of the
upper portions of the mountain, although the natural surround-
ings suggest three possible agencies for such polishing, viz.,
blown sand, ice, and chemical action. The smoothness of the
surfaces and the occurrence of polished surfaces in sheltered
hollows is against any polishing by sand, while the presence of
a crust on somewhat recently formed bowlders and steep slopes,
and the absence of glacial striae militate against any explanation
based on ice action. The thickness of the shell and the decayed
character of the interior, on the other hand, seem to indicate that

GRANITIC ROCKS OF PIKES PEAK QUADRANGLE 220

this crust is due to chemical action. The great diurnal changes
in temperature, the dryness of the air, and the direct action of
the sun tend to promote rapid changes in the amount of moisture
present, and this in turn would cause alternations of solution
and precipitation. Throughout the nights and the winter sea-
sons the rocks receive by capillary action a considerable supply
of moisture which during the day and the summer would take
some of the material from the interior and carry it to the surface,
where there would be rapid evaporation and precipitation. Such
action must be slow, as the material carried out is but slightly
soluble even under favorable conditions; and yet this very
insolubility helps in the final result by rendering at least a por-
tion of the deposited material independent of the rains. The
increased amount of silica in the crust seems to corroborate this
hypothesis of chemical action.t. The formation of a crust on the
rhomboidal joint blocks, together with the closeness of grain of
the rock accounts in great measure for the angularity of the
blocks strewn over the summit, and may in part account for the
present topographic preéminence of this portion of the massif.

CRIPPIEE (GRE EK Wy PE

The granites grouped under this title, compared with those
of the preceding types, appear finer than those of the Pikes
Peak type and more evenly grained than those of the Summit
type. They are finely coherent saccharoidal aggregates of
microcline, vitreous quartz, and glistening biotite with occa-
sional microscopic individuals of zircon, hematite, magnetite,
and apatite. When phenocrysts are present they are usually
microcline, although in an exposure at the Placer Mill northwest
of Cripple Creek, broad glistening flakes of biotite are porphy-
ritically developed.

The most prominent constituents are small, rectangular crys-
tals of fresh pink microcline which occasionally reach the length
of half an inch (Fig. 8). The twinning network is medium coarse

t CrosBy (Merrill, Rock Weathering, p. 255) suggests also the deposition of iron
oxide.

230 EDWARD B. MATHEWS

and therefore differs from that of the other types. This mesh,
however, is not as coarse as that in the smaller, probably second-
ary, microclines present in the same slides, and in the altered
granites more fully described elsewhere. Perthitic intergrowths
with albite are not prominent in the majority of the sections, but
are very abundant in the slides representing some of the

Fic. 8.—Cripple Creek type of the granite.

granites from the vicinity of Seven Lakes. The microclines of
this locality are twinned parallel to the basal pinacoid, according
to the Manebach law, and differ only in size and occurrence
from the large and beautiful amazonstone and orthoclase so well
known from this area. The perthitic lamellae meeting at the
composition face (001) form an angle of 147° and in each case
lie a few degrees from the vertical axis in obtuse @ (parallel to
a steep positive orthodome).*

‘In color and texture this rock resembles the well-known granite from Red
Beach, Me., described in the Tenth Census, and it is probable that if similar rock
can be found where the conditions of quarrying and transportation are favorable it
will prove of economic interest.

GRANITIC ROCKS OF PIKES PEAK QUADRANGLE 231

The irregularly oval grains of quartz composing from one
seventh to one quarter of the rock-mass are either clear and
vitreous, as in the granites from Seven Lakes, or small and
stained with iron, as in the rocks collected in Caylor Gulch.
They are somewhat poor in fluid inclusions but show a great
number of fine ‘‘quartz-needles.’”’ The iron-staining occurs as a
filling in the cracks, rather than as a minutely disseminated pig-
ment or fine evenly distributed hematite flakes.

Like the granites of the Pikes Peak type, those of the Crip-
ple Creek type do not have very much micropegmatite developed
in the fresh specimens, and when it is developed the quartz does
not show the arborescent and radiate growths so abundant in
the weathered and metamorphosed rocks, but is present in small
rounded disks or ovals similar to those described by Romberg.’

The plagioclase occurs in small anhedral grains which are
older than the quartz and the microcline. They are generally
clouded with alteration products which may be either irregularly
distributed through the individual; arranged parallel to the
twinning lamellae; or concentrated in the center with a sur-
rounding clear zone in similar optical orientation. The twinning
lamellae, according to the albite law, are very fine and usually
extinguish almost simultaneously parallel to their composition
face:

The other constituents, zircon, apatite, and magnetite, show
no unusual features and are very sparingly developed.

Distribution —The granites of the Cripple Creek type are
most characteristically developed in the area lying to the west
of a line drawn from Lake George to the town of Cripple Creek
and thence in a somewhat sinuous line to the waters of Oil
Creek. Between this line and the volcanic deposits on the west
is a broad stretch of relatively level country considerably dis-
sected on its eastern side by Oil Creek andi its tributaries.

The contacts against the Pikes Peak type are generally
obscured by the presence of narrow bands of highly metamor-
phosed schists which were included in the older type and cut by

=N. J. B. B-B. VIII, 1892.

232 EDWARD B. MATHEWS

the granites of the Cripple Creek type in a manner well shown
near the mouth of Arequa Gulch a few miles below the town of
Cripple Creek. On the west the contacts with the gneissic
granite are generally obscure, though the finer grained may be
seen cutting the coarser and more schistose rock in Caylor
Gulch at an elevation of 8600 feet.

The manner of weathering and the resulting physiographic
forms are intermediate between those of the Pikes Peak and
Summit types. The hills are neither so smooth, so bold, nor so
massively jointed as those composed of Pikes Peak granite;
while the disintegrated fragments are not as compact and angu-
lar as those of the Summit type. The mineralogical changes
are those common to granitic minerals.

FINE GRAINED TYPE

The rocks included under this head do not occur in well-
defined masses extending over large areas but in small dikes dis-
tributed throughout the entire area studied. Nor are they so
closely allied in their mineralogical and textural features as
members of the preceding three groups. Their correlation is
based upon their composition and texture, mode of occurrence,
age, and present topographic position rather than upon their
areal continuity. All of these rocks are fine grained hypidio-
morphic granular aggregates of reddish color, composed of
quartz, feldspar, and one or both kinds of mica, with small
amounts of microscopic fluorite, magnetite, epidote, zircon, and
apatite.

The color of these rocks varies from brilliant red to pinkish-
white or dull yellow, but is usually bright pink. In the latter
case the feldspars are stained by finely disseminated iron oxide.
The size of the individual grains is very constant, and rarely
exceeds one sixteenth of an inch. Among the individual con-
stituents there are several points of difference from the same
minerals in the earlier types. Quartz is more abundant and in
grains as large or larger than those of microcline, while incipi-
ent granulation shown by a mottled extinction is more frequent.

GRANITIC ROCKS OF PIKES PEAK QUADRANGLE 233

Among the feldspars, microcline shows a slight increase in the
size of its twinning network and the plagioclase a decrease in the
size and abundance of its grains. Perthitic intergrowths are
practically wanting in these rocks, whether fresh or altered,
while micropegmatitic intergrowths are abundant, especially in
the slides where the evidences of mechanical deformation are

Fic. 9.—Fine grained type of granite.

most numerous. The micas show no unusual features beyond
the occasional inclusion of tiny individuals of fluorite showing
well-defined crystal outlines in fresh flakes of biotite.
Weathering. —The effect of atmospheric action on the fine-
grained granites varies somewhat, but is ordinarily less pro-
nounced than that on the other three types. When the rock
disintegrates it usually falls into a mass of angular bowlders of
small size, which are quite compact and sometimes covered with
a surface glaze. This coating, which is faintly shown in Fig. 9,
is much less clearly defined than is that on the Pikes Peak or

234 EDWARD B. MATHEWS

Summit types, and it does not appear to be as commonly devel-
oped. Ledge exposures of this type are comparatively rare, as
The
relatively greater resistance to weathering, due probably to the
more compact texture of the rock, is clearly brought out in the
When the fine-grained
granite occurs in any considerable mass it forms the tops of

minor hills and ridges.

the solid rock is usually covered by angular bowlders.

topographic position of its exposures.

This is well shown in many places
within the area of the map, the best illustration occurring on the
subordinate ridges of the slopes of Pikes Peak and in the rugged
area between Grouse Hill and Red Mountain, on the sides of the
canyon of Crippie Creek.

TABLES SHOWING THE COMPARATIVE ABUNDANCE AND SIZE OF
THE CONSTITUENTS OF THE DIFFERENT TYPES

The comparative abundance, size, and development of the
various constituents in the four types of granite described in the
preceding pages, are summarized in the following tables :

TABLE I. SHOWING RELATIVE ABUNDANCE OF MINERALS
Pikes Peak Summit Cripple Creek Fine grained
OWA > coco odod abundant abundant abundant predominant
Microcline...... predominant predominant predominant predominant
Orthoclase ..... fairly commonly
Oligoclase ..... constant constant constant constant
Perthitic
intergrowths..| well developed | unusual not marked

Micropegmatite .| very rare very abundant | rare present
Hornblende.....| present
ISSIOWUWS 5 o'c 0g ooG6 abundant abundant present present
Muscovite...... common
IMBC scasecoe rare very marked | present
EN OBUINWS 6660.09 06 constant rare eUEE present
Zi conmeeee oe constant present constant constant
Pibitamnite erent present
Eipidoveranennicr rare present
Magnetitemennic: present rare present present
Hematite ...... present present present

GRANITIC ROCKS OF PIKES PEAK QUADRANGLE 235

TABLE If. SHOWING RELATIVE SIZE AND DEVELOPMENT
Pikes Peak Summit Cripple Creek Fine grained
Quartz
SIZe yar rorctsmsleher: Se Om
average m |i 24am Raye -3m
NOMEN 6a dsoo oc irregular spheroidal irregular irregular
Microline (Phenocrysts)
SIZE ee casioeiate 6" X 3” to 25X15 to TES
15x30", A ae
20 X 30™™ as
INGIAT 65 bade 00 well developed | well developed | well developed
Microline (Groundmass)
SIZ ieleriers © aisle HOC Geet DK (Og i <aperten nox gee
ING 6 o.06 000 irregular irregular irregular irregular
Biotite
SWWAS <6 Giecgraee BA I-2™m ra o0.5-1™™
Mode of aggrega-
LKR 50.6 oeNatont single and ag- | single and ag- | single and ag- | single or aggre-
gregate gregate gregate gate
Texture
Coarseness ...| coarse Medium to fine } medium fine
Arrangement ...| granular to granitophyric saccheroidal to | granular
porph. gran. orthophyric(?)
Mode of occur-
HENGS cune coae large masses small masses large masses small masses
and dikes and dikes

The accompanying tables show at a glance the marked simi-

larity in the mineralogical composition, and the equally marked
diversity in the textural relations presented by the different

types.

different types is no more than that due to the presence of occa-

The diversity in the mineralogical composition of the

sional orthoclase, hornblende, sphene, muscovite, or epidote in
specimens collected over an area of more than nine hundred
square miles.
thitic intergrowths to be common in the fresh granites of the

These types, it is true, show well developed per-

Pikes Peak type and wanting in the other types; while fluorite
and micropegmatite are prominent in the rocks of the Summit
type and unusual in the rest of the unaltered granites. The most
striking, most constant, and most characteristic differences
between the types are, however, in the relative and absolute size

236 EDWARD B. MATHEWS

of the constituents, and not in the specific character of the min-
erals present.

The second table shows a variation in the size of the quartz
constituent from grains averaging 5™™" in diameter in the Pikes
Peak type to those of 4%™™ in the fine grained granite. A simi-
lar variation is noticeable in the mica, from flakes of 0.5—-1™™ in
the fine grained type to those of 3-4™™ in the Pikes Peak type.
The microclines also show a similar change in the same direction,
whether they are phenocrysts or not; and in addition the fine-
grained granites show no feldspars porphyriticaliy developed.
This uniform change in the size of the constituents can only
result in the production of a similar variation in the coarseness
of grain, as shown in the tables.

Table I, together with the chemical composition of the
rocks, brings out the similarity or family likeness existing
between the different granites; a likeness that signifies their
origin from a common magma relatively rich in silica and fluo-
rine. Table [I], with the field relations, substantiates this view
and explains the many local differences shown in texture, or
mode of aggregation, of the different constituents. The coarse-
grained Pikes Peak and Cripple Creek granites formed large
masses, while the Summit and fine grained rocks occur in physi-
cal conditions sufficiently variable to account for the variations
in texture which distinguish the rocks of these types.

CHEMICAL COMPOSITION

The marked uniformity in the mineralogical composition of
the various granites from all portions of the area suggests a
similar uniformity in the chemical composition. The abundance
of quartz and perthitic microcline, with the small amounts of
plagioclase, mica, and accessory minerals, indicate a relatively
high percentage of silica and the alkalis, with a comparatively
small amount of calcium, iron, and magnesium. The presence
of fluorite, also, suggests the actually small, but relatively high,
percentage of the unusual constituent fluorine. These inferences
from the mineralogical composition are fully sustained by the

GRANITIC ROCKS OF PIKES PEAK QUADRANGLE

following complete and careful analyses made by Mr. W. F.
Hillebrand of the U. S. Geological Survey.

TABLE OF CHEMICAL ANALYSES
I II III IV Vv
(2128) (2531) (2530) (2369)
SS) asic ca OneiereeS 77.03 75.17 Bait 73.90 74.90
1,284 I.253 I,225 I,221 1.248
IMO oaue ciclo 13 .10 .18 07 a2
.OOT -OOT .002 .000 2OOT
IM O@ln ooaau's 3 12.00 12.66 13.28 13.65 12.89
.116 .122 .129 +132 .125
Hea Op ccnys cer .70 22) 94 28 58
+004 .OOT .006 .OOT .003
HEOR Moe cct ss .86 1.40 .O7 42 .QI
or2 fede) O13 005, .O12
(NEMO) ood eisai lines tr. life tires! alin eee eae
CVO aatievarene .80 83 I.II DB 74
O14 .OI14 020 .004 O13
oul O)eravetersiacs ally Bette te eee Our yall <a wervettsencich hell's la Pass onakoreer ol Wee Sateen ean
BAO Ss ostese sass tr. .03 (tie. (Cicer any PP aye tee ten fs
INI Oi reteis fost hi -04 05 .05 .14 .07
,OOT .OT .OOT -003, .OOT
KR Ol sats cee 4.92 5-75 5.22 7.99 5.92
1052 Roloha 2055 .085 .063
INGOs arene 3.21 2.88 3.79 2.53 3.10
.O51 .046 .061 +040 +050
CTO) S Bierereeese tr. Sls (iF, tr. (HMO dl oi cdeeae te
MIG OM oe onc 14 .16 .16 15 51
Hin Oi .30 62 31 .92 55
Ban ©) esreess sts) ss tr. 03 tr. 05 02
eres tyei sce e'd 36 ahi! SSSR AIP W) crwiavas oredls 31
GO pra8 3's sloteelll aay ees hater canal (avo R nen oerer Ren [ie peeesec tlc eas Pease anne Paes
100.55 100.26 100.38 QOS ili iliers: ae
Mess Eso... 55 3B RD ORIN Ones acheter etch eh [k ages eee
100.40 100.13 100.16 99.75 100.26

237

* Below 110° C. { Above 110° C.

I. (2128.) A coarse grained granite of the Pikes Peak type
taken from the western side of the Pikes Peak massif at a place

238 EDWARD B. MATHEWS

called “Sentinel “Poimt)(12\400) feeh)py wkieldsparn us athe most
important constituent, with quartz very abundant in somewhat
smaller grains. The mica occurs in both single individuals and
in aggregates of minute flakes. A thin section of this rock is
composed, almost entirely, of quartz and microcline, the latter
showing a few lamellae of perthitic plagioclase.

II. (2531.) A porphyritic granite of the Summit type col-
lected from the divide tunnelled by the Colorado Springs Water-
works (elevation about 12,000 feet). This is composed of
feidspars and large grains of quartz in a fine grained, reddish
to purplish groundmass.

III. (2430.) A fine grained variant of the Summit type col-
lected on the head waters of the Middle Beaver, nearly opposite
the Bear Creek road to the Colorado Springs Water-works. . The
prominence of the biotite against a fine grained groundmass of
feldspar, and the peculiar purplish hue due to the disseminated
fluorite, are the chief characteristics.

IV. (2369.) A fine grained granite of the fourth type taken
from Smith’s Gulch not far from Current Creek P. O. This is
composed of quartz and microcline with small amounts of mica.

V. An average of the preceding.

The following conclusions based on a comparative study of
the analyses seem to be warranted by the figures. When the
individual analyses and their average are reduced to molecular
proportions and compared with an average of twelve type analy-
ses given by Zirkel* and several analyses given by Rosenbuch?
similarly reckoned, it is seen that they all are richer in silica than
the averages given in the text-books, though not richer than
individual specimens from many areas. The sum of the alkalis
seems to conform to that of the averages but the granites of
the Pikes Peak area are relatively richer in potassium. This
relation between the alkalis becomes of additional interest when
the occurrence of nepheline-bearing rocks near Cripple Creek is
considered.

t Lehrbuch der Petrographie, 2te. Aufl. II, p. 29.

2Elemente der Gesteinslehre, p. 186.

GRANITIC ROCKS OF PIKES PEAK QUADRANGLE 239

Among the elements represented, fluorine is of the most
interest. Although small in amount the still smaller quantities
of lime and phosphorus show that there is enough present to
satisfy all of the latter even in the form of pure fluor-apatite, and
much of the former in the form of fluorite. The possible excess
of calcium is so small that the plagioclase plates must be sodium
rich oligoclase and the perthitic pegs albite.

The low percentage of iron and magnesium together with the
strong pleochroism of the mica explains the relative scarcity of
this mineral.

The chemical analyses confirm the microscopic determina-
tions and show that the general magma was of such a composi-
tion as might produce a rock composed essentially of a potassium
feldspar, perhaps intergrown with albite, and considerable quartz,
with small amounts of fluorite and iron rich mica.

RESUME

The area included within the Pikes Peak quadrangle is a com-
plex of granites, gneisses and schists overlain by numerous
sedimentary and volcanic rocks of later age. The unaltered
granites show, over an area of more than a thousand square
miles, a notable uniformity in their mineralogical and chemical
composition which is marked by the persistent presence of
holocrystalline quartz-microcline aggregates bearing small
amounts of equally constant biotite. On the other hand, these
same rocks show a distinct diversity in the abundance, size, and
form of their constituent minerals and the consequent differences
in texture.

The variations in texture and composition are as follows:

Pikes Peak type-—Coarse granular to coarse porphyritic:
rich in perthitic feldspar, poor in micropegmatitic intergrowths,
and fluorite with occasional hornblende and titantite.

Summit type — Granitophyric; poor in perthitic feldspars but
rich in micropegmatite and fluorite.

Cripple Creek type —Saccharoidal with rectangular feldspars ;
poor in perthitic feldspars, micropegmatite, and fluorite.

240 EDWARD B. MATHEWS

Fine grained type.— Fine granular ; poor in perthitic feldspar,
micropegmatite, and fluorite but bearing some muscovite.

Emphasis has often been laid on the variations in the chemi-
cal or mineralogical composition of masses showing uniformity
in their texture. The present instance represents on a large
scale the opposite changes. Here there are well-defined differ-
ences in texture in a mass of uniform chemical composition.
The changes in mineralogical composition are slight, and
represent little or no difference in the chemical proportions of
the mass except in the case of the fluorite. The other changes
are local and partake of the nature of ‘‘dark patches.”

Besides these original differences in the textures there are
others of secondary origin where the feldspar phenocrysts have
become lenticular ‘‘eyes”’ and the massive granites have been
changed to granite-gneisses.

Epwarp B. MATHEws.

A NORTH AMERICAN EPICONTINENTAL SEA OF
JURASSIC. AGE

I. Introduction.
1. Statement of the lines of investigation.
II. Nature and extent of the sea.
1. Present known distrfbution of the deposits.
a') South Central Wyoming area.
6') Southeastern Idaho area.
c') Northern Uinta area.
d') Southern Uinta area.
e') Southern Utah area.
J’) Black Hills area.
g') Montana area.
A') Canadian area.
z') Aleutian area.
2. Conclusions.
III. Relation of the interior fauna to the northern Eurasian fauna,
IV. Connection of the sea with the ocean.
V. Lack of communication between the Californian province and the interior,
and the causes assigned.
1. The climatic hypothesis.
2. An alternative hypothesis.
VI. General conclusions.

INTRODUCTION

The following line of investigation is the out-growth of the
study of the faunal and stratigraphical conditions as they are
expressed in the Jurassic formation of the Freeze-Out Hills in
southern Wyoming.’ In making these investigations the writer
has been led to test, in the light of new doctrines * and more
recent observations, certain prevalent opinions bearing on Juras-
sic faunal geography. In connection with these investigations
there arose also questions concerning which no definite statement

tLoGAN: Kansas Uni. Quart., April 1900.

2See papers by Dr. T. C. CHAMBERLIN on: “A Source of Evolution of Provin-
cial Faunas,” Jour. GEOL., Vol. VI, p. 598; “‘ The Ulterior Basis of Time Divisions,”

2bid., p. 449.
241

242 W. N. LOGAN

of opinion has as yet appeared in our geological literature.
Among the lines of investigation which suggested themselves
were the following: (1) The nature and extent of the interior
Jurassic sea; (2) the relation of the interior fauna to other
faunas; (3) the connection or connections of the sea with the
ocean; and (4) the causes for the lack of communication
between the Interior province and the Californian faunal prov-
ince: ;

Some of these questions, notably the second and fourth, have
already received a somewhat exhaustive discussion at the hands
of a number of geologists. In the majority of cases, however,
the conclusions formed have been connected with certain funda-
mental assumptions concerning the validity of which there is at
present profound skepticism. As these new doctrines are more
or less intimately associated with new fundamental hypotheses,
a test of the one is in a measure a test of the other; but a dis-
cussion of original postulates does not fall primarily within the
province of this investigation. Therefore the discussion will pro-
ceed along the lines already indicated and in the order above
mentioned.

Nature and extent of the sea.—I1n order to present the data
upon which our conclusions concerning the nature and extent
of the Jurassic sea are based it will be necessary to give a sum-
mary of the stratigraphical and faunal conditions of the present
known Jurassic areas. In collecting this data I have consulted
the writings of a long list of geologists who have labored in this
particular geological field.t | On the whole it may be said that
the results obtained by these men are strikingly harmonious ; so
that no grave difficulty should be met in any attempted logical
interpretation of the facts.

These Jurassic areas will be discussed in the order which fol-
lows: (1) The South Central Wyoming area; (2) the Southeast-
ern Idaho area; (3) the Northern Uinta area; (4) the Southern
Uinta area; (5) the Southern Utah area; (6) the Black Hills area ;
(7) the Montana area; (8) the Canadian area; (9) the Aleutian

t For references see following discussion.

EPICONTINENTAL SEA OF JURASSIC AGE 243

area. Many of these terms have been used in a loose geographic
sense since the object is to include under one name all of the
minor localities belonging to one areal province. The numbers
on the map’ indicate the position of these areas.

THE SOUTH CENTRAL WYOMING AREA

The Freeze-Out Fiills.?—The oldest rocks recognized in the
Freeze-Out Hills are the Carboniferous. They occupy the cen-
ter of the partly dissected anticline and are overlain by the Red
Beds which are composed of sandstones and reddish arenaceous
clays and marls inclosing here and there lenticular masses of
gypsum or gypsiferous clays. These beds are seemingly devoid
of fossils and are apparently conformable with the overlying
Jurassic beds of unquestionable marine deposition. At a point
on the Dyer Ranch the following stratigraphical conditions of
the contact between the Red Beds and the Jura were noted in
ascending order :3

Ipebase wear toprorctne Wed Beds) reddish clay. )2) a:
White, indurated sandstone, 4” ;
Clay iiehtared as
White sandstone with a reddish tinge, 1’;
Wight red! clay, 27 ;
White, slightly indurated sandstone, 6° ;
Shale, reddish changing to purple, 4’ ;
White fissile arenaceous limestone, 0’ ;
Arenaceous clay of,a dull red color, 10’ ;

oO © ON Am WwW DN

_

White laminated arenaceous limestone containing fossils,

OV

This last stratum contains a characteristic Jurassic type,
Pseudomonotis curta Hall. This is the first or lowest known fossil
bearing horizon of the Jura in this area. Any division line
between the Red Beds and the Jura placed lower than this fossil
bearing stratum would be an arbitrary one as there appears to
be no unconformity to mark the separation. To the beds occur-
ring above the fossiliferous horizon the term Jura-Trias is no

aISee ps 2415. 2LoGaN: Kansas Uni. Quart., April 1900.
3 Quoted from paper mentioned above.

244 W. N. LOGAN

longer applicable as they are unquestionably Jura. As the Red
Beds represent the whole interva) of time from the Carbonif-
erous to the Jurassic so far as evidence to the contrary is con-
cerned the term Jura-Trias alone is not applicable to them.

Continuing the section already begun we have for number

11. Arenaceous clay of a somewhat shaly nature, 6’. This
layer contains near the central horizon a more highly arenaceous
stratum of greenish color. It has scattered through it at different
levels some rather large brown argillaceous concretions. The
entire stratum seems to be unfossiliferous but it may contain
Belemnites densus as it is often difficult to determine whether this
fossil does, or does not, belong to the lower beds, since, on
account of its abundance in the upper beds, it is usually scat-
tered superficially throughout the full extent of the outcrop.

12. White sandy clay, 4’. No invertebrate fossils were
found in this stratum but the remains of marine saurians belong-
ing to the genera, /chthyosaurus and Plestosaurus occur in consid-
erable abundance.

13. Purplish fossiliferous clay containing calcareous nodules,
20’. The most abundant fossil in this stratum is Belemnites
densus which occurs distributed throughout the layer while the
other fossils are confined chiefly to calcareous concretions. From
these concretions the following forms were obtained: Pinna
kingi Meek; Cardioceras? cordiforme M. & H.; Belemnites densus
M.& H.; Astericus pentacrinus M. & H.; Astarte packardi White ;
Pleuromya subcompressa \White; Pseudomonotis curta Hall; Lan-
credia bulbosa White; Goniomya montanaensis Meek; Tancredia
magna Logan; Lima lata Logan; Belemnites curta Logan; Car-
dinia wyomingensis Logan and Avicula beedei Logan. This
stratum contains also the remains of Plestosaurs and ILchthyosaurs.
It is the most abundantly fossiliferous of the entire series. It is
also one of the most persistent beds, and is everywhere charac-
terized by the great abundance of Lelemnites.

14. Greenish colored sandstone separating into thin layers,
2’ to 4’. This stratum is very persistent, contains considerable
calcareous matter, and is easily recognized on account of its

245

EPICONTINENTAL SEA OF JURASSIC AGE

Vv

Soma peasy

4
!
!
!

1

!

Map showing the distribution of the Jurassic formation in the interior.

I.

LIKE

246 W. N. LOGAN

uniformly greenish color. The following fossils occur in it:
Camptonectes bellistriatus Meek; Camptonectes extenuatus M. & H.;
Gryphea calceola var. nebrascensis M. & H.; Ostrea strigilecula
White and Ostrea densa Logan.

15. Purplish clay containing considerable arenaceous inclu-
sions, 40’. The clay contains in the upper part a thin strata of
sandy limestone in which the following fossils were found:
Pentacrinus astericus M. & H.; Asterias dubium White; Pseudomo-
notis curta Hall; Avicula macronatus M.& H.; and Ostrea strigile-
cula White.

Como beds.—The last stratum is the uppermost one, containing
marine fossils and probably closes the Jura. The succeeding
layer varies so much in thickness within short distances that it
may represent the slightly eroded surface upon which the Como
beds were deposited.

“16. Fine-grained, grayish-white sandstone, 10’ to125’. The
above stratum varies much in thickness within short distances.
At one point on the Dyer Ranch it has a thickness of 10’, while
a few miles southeast of that point it reaches a thickness of 125’.
The sandstone composing the layer is of nearly uniform color
and texture. Its induration is only moderate, and it weathers
into many grotesque forms. Cross-bedding is well exhibited by
it in many localities.

17. Purple to greenish colored clay, 60’. This is apparently
an unfossiliferous layer except in the uppermost horizon, where
species of Dinosaurs belonging to the genera Avontosaurus and
Morosaurus occur. This is the lowest fossiliferous horizon of the
Como beds and the beds included between this horizon and the
layer marked 15 may represent the transition from marine to
non-marine conditions.

ids, sandstones orayishw to ight brown, lO) tonZo) elite
above sandstone presents some very interesting stratigraphical
phenomena. It has at the base a layer of conglomerate about
2%’ thick. The conglomerate is composed of small argilla-
ceous and silicious pebbles, and is not very coherent. Something
like two feet of sandstone rest upon the conglomerate; the

EPILCON LINPNDLAETSZA "OP JURASSIC AGE 247

bedding planes of the sandstone are oblique to the beds above
and below. Succeeding the sandstone above is 6" of sandstone
in very thin layers, with lignitic seams along its horizontal but
wavy bedding planes. The above is overlain by 4" of conglom-
erate followed by 1’ of sandstone with oblique bedding planes.
Overlying this layer is a thin layer of sandstone in which the
bedding planes are horizontal. The remainder of the stratum is
made up of sandstones with the thicknesses and bedding planes
as follows: 1’ oblique; 3" horizontal; 2’ oblique; and finally 3”
horizontal.

The beds furnished in one place the trunk of a large fossil
tree and a large number of fossil cycads. Fragments of wood
were found in a number of places, but cycads in only the one.
Fragments of a hollow-boned Dinosaur were secured from one
place in the horizon.

19. Drab-colored clay, 30’ to 40’. This stratum contains
the remains of Srontosaurus and Morosaurus. Otherwise it
appears to be unfossiliferous.

20. Fissile, brownish sandstone, 4’ to 5’. No fossils were
found in this sandstone, and a most characteristic feature about
it is its uniformly brown color. It seems to be moderately per-
sistent, as it was noticed in many places in the hills.

21. Bluish-green clay, containing very small concretions, 30’.
In the bone quarries of this horizon, which furnished species of
Brontosaurus, Morosaurus and Diplodocus were found specimens of
Lioplacodes (Planorbis) veternus Meek, and Valvata leer Logan.
This is the lowest horizon at which any of these non-marine
invertebrates were noticed. It is very probable that they will
be found in the beds below as they indicate similar conditions of
deposition.

22. Brown to bluish-gray arenaceous limestone, 8” to 1’.
This stratum contains the following non-marine invertebrate
forms: Unio knighti Logan; Unio williston’ Logan; Unio baileyi
Logan; Valvata leei Logan; and Lioplacodes (Planorbis) veternus
Meek. Species of the same genera have been described by
Meek from a similar stratum of limestone in the Black Hills.

248 W. N. LOGAN

As these occupy much the same stratigraphical position they are
very likely of the same age. The Lzoplacodes seems to be identi-
cal with that described by Meek in the Geology of the (Ulpipies
Missouri.

23. Drab-colored clay, 70’. Species of the genera Svonto-
saurus, Diplodocus, Morosaurus, Stegosaurus and Allosaurus occur
in this horizon. Portions of species of all these genera were
found in one quarry by the Kansas University collecting party of
which the writer was a member. The clay is of that quality
usually designated as joint clay. It contains, in places, iron and
argillaceous concretions of small size. The iron and sometimes
the bones are covered with small selenite crystals.

24. Grayish-white sandstone, 50’. This layer forms a con-
spicuous capping for the hills, and is the highest remnant of the
anticline. It breaks up into large blocks, which lie scattered
along the slopes of the underlying softer beds. Its erosion and
disintegration is accomplished chiefly by sapping. No fossils
were found in this stratum” (Dakota ?).

The maximum thickness of the Jura for this bese does
not at the most exceed 100 feet. All of the fossils are found in
a vertical range of but little more than half that distance, and
yet the fauna includes all the characteristic species of the
interior Jurassic province. The beds are heterogeneous and
indicate constantly varying conditions of sedimentation.

The entire section is given in its minutest details so that an
idea of the general character of the Como beds may be obtained.
In many localities this formation has been included in the Jura,
although the Jura is wholly marine while on the other hand the
Como is wholly fresh water. On the whole the marine beds are
more calcareous but there is usually at least one thin bed of
limestone in the Como. The lithological characters of the beds ,
do not always stand out so clearly that the evidence of fossils
is not required to separate the beds.

Como Lake.—Vhe stratigraphical conditions of the formation
at Lake Como are not essentially different from those of the

1 LOGAN: loc. cit.

EPICONTINENTAL SEA OF JURASSIC AGE 249

Freeze-Outs. The beds have the same lithological character-
istics, being composed of sandstones, arenaceous clays, marls
and impure limestones. They rest on the Red Beds and are
overlain by about the same thickness of the Como (Atlanta-
saurus) beds. The latter formation is capped by an apparent
continuation of the same quartzitic layer which forms the surface
stratum in the Freeze-Outs. From this area the following spe-
cies have been determined by the writer and others: Asterias
dubium, Pentacrinus astericus; Belemnites densus; Cardioceras?
cordiforme; Pseudomonotis curta; Camptonectes bellistriatus; Ostrea
strigilecula; Ostrea comoensis; Pinna kingi; Tancredia inornata;
Pleuromya subcompressa; Astarte packardi; and Goniomya montan-
aensts.

Rawlins Peak.—The Jurassic at this point exhibits about the
same thickness and lithological characters as that of the Como
area. The beds contain the following forms: Camptonectes bel-
histriatus ; Belemnites densus,; Astarte packardi; Pseudomonotis curta ;
Ostrea strigilecula; and Pentacrinus astericus.

Sweetwater.—In the Sweetwater Drainage area Endlich * gives
300 feet as the thickness of the jura at that place and states that
it contains a Gryphea and a Belemnites.

East of the Wind River Range according to the same writer?
the Jura has a thickness of 200 or 220 feet and consists at the
base of dark calcareous shales, covered by beds of dark blue lime-
stones. These are followed by yellow shales and marls with
intercalations of thin sandstone layers. Yellow, pink and green-
ish marls close the section. The fossils obtained are species of
Belemnites, Gryphea, Rhynchonella, Lingula, Modiola, Pecten, and
others.

THE SOUTHEASTERN IDAHO AREA

In this area St. John3 places the thickness of the Jura at
2000 feet. Since, however, only the lowermost beds are fossil-
iferous it is probable that the Jura should be restricted to that

*Ann. Rep. U. S. Geol. Surv.; Vol. XI, 1877, p. 108.
2 (bid. p. 87.
3Ann. Rep. U.S. Geol. Surv., Vol. XI, 1877, p. 495.

250 W. N. LOGAN

horizon. The beds consist here as elsewhere of alternating beds
of sandstone, shales, and limestones.

In the Lincoln Basin the following Jurassic fossils were col-
lected: Ostrea strigilecula,; Belemnites densus,; Pentacrinus, Ostrea,
Gryphea, Camptonectes, and Pseudomonots.

At Meridian Ridge Peale* found 150 feet of bluish and gray
limestones ; bluish laminated limestones and bluish argillaceous
shales and slates followed by 100 feet of reddish sandstone and
bluish limestone containing Pentacrinus astericus ; Ostrea strigilec-
ula, Camptonectes bellistriatus and other forms. This thickness of
250 feet doubtless represents a conservative average for the
SnibineNCiSimct

On the John Day (Gray) River? the following fossils were
collected: Pentacrinus astericus; Belemnites densus; Camptonectes.
bellistriatus ; Gryphea, Trigoma, and Pleuromya; and from another
outcrop, Pentacrinus astericus ; Ostrea strigilecula, and Tancredia sp.
An outcrop in the Sublette Range furnished Pentacrinus astericus
and Camptonectes bellistriatus.

The Jura at Bear Lake Plateau3 contains Pseudomonotis curta
and other forms. The fossiliferous beds consist of 90 feet of
gray limestone and 80 feet of bluish-gray limestone with bands
of sandstone. This group rests on 150 feet of limestone which
may also be Jura but there is no faunal evidence of its age.

On Bear River in Southwestern Wyoming Meek‘ gives the
following section for the Jura: ‘‘ Ferruginous sandstone, in thin
layers, dipping northwest about 80° below horizon, 40 feet;
bluish laminated clays with, at top (left or west side), a two-
foot layer of sandstone containing fragments of shells not seen
in a condition to be determined, 125 feet ; Clays and sandstones,
below (20 feet); gray and brown pebbly sandstone above (25
feet), 45 feet; brownish and bluish clays, with some beds of
white, greenish, and brown sandstone, 115 feet.” From the
second layer the following fossils were obtained: Belemmnites

™ Ann. Rep. U. S. Geol. Surv., Vol. XI, 1877, p. 536.

2 Ibid. p. 544. 3 Ibid. p. 585.

4Ann. Rept. U. S. Geol. Surv., Vol. VI, 1872, p. 451.

EPI CONTLNEN PAL SHA OP fURA SSiEVAGE 251

densus, Trigonia Quadrangularis, and Pleuromya weberensis ? This
stratum of 125 feet is all of the section that can, with certainty,
be assigned to the Jura, as the other layers are unfossiliferous.

The third and fourth layers correspond in character to the
Como beds in other areas in Wyoming.

THE NORTHERN UINTA AREA

Flaming Gorge..—I\n the Flaming Gorge the total thickness
of the Jurassic is placed at 700 feet. Three hundred feet near
the middle of the outcrop contains: Camptonectes bellistriatus ;
Gryphea calceola; Pentacrinus astericus; Rynchonella gnathophora ;
Trigonia americana, Trigonia conradi,; Ostrea strigulecula ; and Belem-
nites densus. In the absence of fossil evidence the portion of the
outcrop lying above and below this horizon cannot with cer-
tainty be assigned to the Jura. Therefore it is possible that the
three hundred feet represents the whole thickness of the Jura
for this area.

South of Dead Man’s Springs calcareous beds which are
thought to represent the middle part of the Jura for that area
contain: Camptonectes bellistriatus ; Myophoria lineata; Gryphea cal-
ceola; and Pentacrinus astericus.

Vermillion Cliffs?—From Vermillion Cliffs in Northwestern
Colorado White determined the following Jurassic species:
Belemnites densus; Cardtoceras cordiforme,; Pentacrinus astericus ;
Rhynchonella gnathophora; Rhynchonella myrina,; Ostrea strigile-
cula; Ostrea procumbens; and Modiola subtmbricata.

The limits of the Jurassic sea in a southeasterly direction do
not appear to have been far from this point. Northwestern
Colorado has up to this time been the only part of the state to
which unquestionable Jura could be assigned.

On Sheep Creek a basal limestone yielded Camptonectes bel-
listriatus; Myophoria lineata; Gryphea calceola; Pentacrinus astert-
cus; Belemnites densus; and specimens of Ostrea, Trigonia, and
Volsella.

*KinG: Geology of the goth parallel, Vol. I, p. 290.

2 WHITE: Geology of Northwest Colorado, U.S. Geol. Surv., Vol. XII, 1878.

252 W. N. LOGAN

THE SOUTHERN UINTA AREA

Ashley Creck."—The thickness of the Jurassic beds on Ashley
Creek is estimated to be about 750 feet. Of this thickness 50 feet
are blue and drab colored shales and limestones carrying Gryphea
calceola, Pseudomonotis (Eumicrotis) curta and Belemnites densus.
This stratum corresponds to the more densely fossiliferous zone
of other localities. As the vertical range of the fossils is not
given it is difficult to say whether all of the 750 feet should be
included in the Jura.

Near Peoria on the western end of the range a basal lime-
stone contains Pseuwdomonotis curta and is followed by a group of
shales and marls. No thicknesses are given for this area.

Wasatch Range.2—In Weber canyon of the Wasatch Range the
Jurassic is estimated to have a total thickness of 1600 feet. The
lower part which consists of yellow and bluish limestones and
calcareous shales has a thickness of 600 feet. It contains the
following fossils: Cucullaea haguet;, Pleuromya subcompressa,
Myophoria lineata; Myophoria sp. and Volsella scalpra. As the
upper 1000 feet of arenaceous texture is unfossiliferous it is
more than probable that it is not of Jurassic age. As the ver-
tical range of the fossils is not given we have no means of ascer-
taining how much of the 600 feet may, also, belong to another
period.

At the mouth of Thistle Creek in Spanish Fork Canyon the
following fossils were found: Lyosoma powelli, Camptonectes
stygius and Pinna sp.

THE SOUTHERN UTAH AREA

According to Dutton3 the known Jura of Southern Utah hasa
thickness of from 200 to 400 feet. The formation consists of a
series of calcareous and gypsiferous shales. The beds are dis-
tinctly fossiliferous and thin out toward the south, entirely dis-
appearing in northern New Mexico and Arizona. A few fossils
have been collected from a number of localities in the region.

*KinG: Geology of the goth Parallel, Vol. I, p. 292.

2 KING: l. c. p. 293. 3 Geology of the High Plateaus, Utah, p. 150.

EPICONTINENTAL SEA OF JURASSIC AGE 253

From specimens collected on the Santa Clara River two miles
below Gunlock White determined the following species: Penta-
crinus astericus M.& H.; and 7rigonia sp. Wh.; from near Kanara:
Pentacrinus astericus M. & H.; Camptonectes stygius White ; Camp-
tonectes bellistriatus M. & H.; from the northern part of aquarius
plateau; Camptonectes platessiformis White; Trigonia montanaensts
Meek and Gervillia sp. White; from Potato Valley, Diamond
Valley, and near Gunnison: Pentacrinus astericus M. & H.

From the geographic distribution of the Jura in this region
it appears that the Jurassic sea did not extend far south of the
southern boundary of Utah. It may be assumed also that its
eastern as well as its western shore lines did not extend in this
region much beyond the state boundaries. From this point the
eastern shore line extends farther and farther east crossing the
northwest corner of Colorado thence continuing toward the
northeast and including the Black Hills area.

The thinning out of the beds toward the south may be due
to the presence of a low land area at the south during this epoch.
A high land area should give a thick shore deposit of a coarse,
clastic nature. According to the above statements, however,
the beds consist of calcareous and gypsiferous shales which
indicate either a somewhat remote shoreline or a low bordering

land area.
THE BLACK HILLS AREA’

The Jurassic formation forms one of the members in the rim
of sedimentary rocks which encircles the crystalline area of the
Black Hills. Here as in the central and southern areas the Jura
rests upon the Red beds and is overlain by the Lower Cretaceous,
the Como beds. Its thickness is in the neighborhood of 200
feet. It exhibits in general about the same lithological characters
that are noticeable in the formation in the Southern Wyoming
area. The beds consist of sandstones, arenaceous shales and
marls, and thin beds of impure fissile limestone.

Whitfield? has determined the following species from this

*JENNEY: Nineteenth Ann. Rep. U. S. Geol. Surv., p. 593.

? Geology of the Black Hills, 884.

254 W: N. LOGAN

area: Asterias dubium Whitt.; Pentacrinus astericus M. & H.; Lin-
gula brevirostris M. & H.; Rhynchonella myrina M. & H.; Ostrea
strigilecula ‘White; Gryphea calceola, var. nebrascensis M. & H.;
Pecten newberryt Whitf.; Camptonectes bellistriatus M.; Campto-
nectes extenuatus M. & H.; Pseudomonotis curta Hall; Pseudomono-
tis orbiculata Whitf.; Avicula (Oxytoma) mucronata M. & H.;
Gervilta recta M.; Grammatodon inornatus M. & H.; Mytilus
whiter Whitf.; Volsella (Modiola) formosa M. & H.; Volsella per-
temus M. & H.; Astarte fragilis M. & H.; Trapezium belle-
fourchensts Whitf.; Tvrapezium subequalis Whitf.; Pleuromya
newton. Whitf.; Zancredia inornata M.& H.; Tancredtia corbulh-
formis Whitf.; Tancredia bulbosa Whitt.; Tancredia postica Whitt ;
LTancredia warrenana M. & H.; Dostna gurassica Whitt.; Psammo-
bia? prematura Whiti.; Thracia? sublevis M. & H.; Neaera
longirostra Whitf.; Saxtcava jurassica Whitf.; Quenstedtoceras
( Cardioceras) cordiforme M. & H.; and Belemnites densus M. & H.

In the Big Horn Basin region Eldridge* discusses the Jura
as follows: ‘This, so far as the evidence obtained indicates, is,
within the region under examination, wholly of marine origin.
The thickness is between 400 and 600 feet, which is approximately
maintained over the entire area of exposure. Shales constitute
the mass of the formation in which from base to summit occur
thin beds of sandstone and fossiliferous limestone of types char-
acteristic of the Jura in the Rocky Mountain region. Gray is the
predominating color of the shales, but throughout the formation
red, purple, yellow, slate, and pink, in greater or less intensity,
may be observed. At a number of localities a considerable
amount of siliceous matter appears, in occurrence suggesting the
action of hot waters.

‘The sandstones are of slight importance. They are chiefly
gray with a slight greenish tint. The lower beds, however, are
red, shaly and transitional from the Trias, while near the sum-
mit are two of greater thickness, which, but for their tint and
the overlying typical Jura shales, might be confounded with the
Dakota.

tBull. U. S. Geol. Surv. No. 119.

EPICONTINENTAL SEA OF JURASSIC AGE 255

‘The limestones are nearly all fossiliferous, and of the drab
color peculiar to the Jura in the west. In thickness they vary
from a few inches to 15 feet. Three or four in the lower 100
feet and one or two in the upper third of the formation are espe-
cially prominent.”

The formation is said to be overlain by the Dakota sand-
stone. If this so-called Dakota sandstone is at the same hori-
zon that it is in the Freeze-Out Hills, and it seems from the
description very probable that it is, then the Jura so-called
must include the Como beds. The description of the upper
part of the formation fits the Como, while the lower part with its
fossiliferous limestones is very characteristic of the Jura both
north and south of this area. The Como or its stratigraphic
equivalent is recognized both north and south of this region and
there appears no good reason for its absence in this area.

THE MONTANA AREA

Castle Mountain.A—Vhe Jurassic formation in this area is less
than one half the average thickness for the interior. Its maxi-
mum thickness is only ninety feet. The formation consists of a
basal sandstone overlain by a dense white limestone. The lime-
stone layer is highly fossiliferous and contains the following
well-known Jurassic forms: Astarte packard; Trigonia montanaen-
sis; Pinna kingt; Pholadomya kingt,; Ostrea sp.; Camptonectes
extenuatus,;, and Gervillia montanaensts.

The Jura of this locality rests upon upon the Carboniferous
and the Red Beds are not represented. It is the belief of the
writers that the beds are wanting altogether in Montana, or at
least but sparingly represented.

Little Rocky Mountains.2—Vhe total thickness of the Jura for
this region is placed at 100 feet. The beds consist of shaly
gray limestones which change to impure, marly shales and argil-
laceous limestones. They rest on limestones of Carboniferous
age and the Red Beds are again absent.

™WEED and Pirsson, Bull. 139, U. S. Geol. Surv., 1896.

* WEED and PIRSSON, JouR. GEOL., Vol. IV, 1896.

256 W. N. LOGAN

The Jurassic limestones contain the following species: Astarte
meeki,; Belemnites densus; Pleuromya subcompressa; Gryphea cal-
ceola, var. nebrascensis; and a fragment of an undetermined
Ammonite.

This is one of the most northerly areas from which Jura has
been recorded for Montana. If the formation is present in
the Bear Paw Mountains which lie to the northwest of this area
it has not been differentiated.

Three Forks—The Jura has a thickness in this area of from
300 to 400 feet. The lower beds rest on a basal quartzite and
consist of argillaceous limestones which carry characteristic
Jurassic fossils. The middle and upper beds are more arena-
ceous than the lower beds and are non-fossiliferous. Under
such conditions it is very questionable whether they should be
assigned to the Jura. It is very probable that the thickness of
the Jura in this area conforms more nearly to that assigned to it
in other areas of Montana.

Livingston.2—The Jurassic formation of the Livingston area
has a thickness estimated at 4oo feet. It consists at the base of
a massive, cross-bedded, ripple-marked sandstone. This sand-
stone is overlain by a layer of impure fossiliferous limestone
containing Pleuromya subcompressa M. ‘The limestone is fol-
lowed by a bed of arenaceous limestones containing shell frag-
ments. Since the lower layer is non-fossiliferous it may or may
not represent a part of the Jura, but there is the possibility of
an overestimation of thickness here as well as in the Three
Forks area.

Although the thicknesses given for the Three Forks and
Livingston area are not extremely large, yet they are nearly
double that given for the other Montana areas. But as has been
pointed out, this lack of harmony may be due to the inclusion
of beds belonging to other formations. If the faunal relations
are not carefully worked out in connection with the stratigraphy
errors are likely to occur either in the direction of the overlying

t PEALE, U.S. Geol. Surv., Three Forks Folio, 1896.

2IpDINGS and WEED, U.S. Geol. Surv., Livingston Folio, 1894.

EPICONTINENTAL SEA OF JURASSIC AGE 257

or the underlying beds. For the Jura in many localities, so far
as physical characters are concerned, grades almost impercep-
tively into the Red Beds below and the Como above.

Judith Mountains.*—Weed and Pirsson give the following
section as representing the Jura in the Judith Mountains.
The base is separated from the Carboniferous by a sheet of

porphyry.

Feet,
Limestone, dark gray, laminated, and shaly - - - - 10

2. Limestone, blue to gray in color, hard in texture, and carrying
Ostreze in 3 to 5-foot beds, separated by thinner platy beds - 12
3. Noexposure - . - - - = - - - - 25

4. Shaly, argillaceous, impure limestone, dove colored, weathering buff
on joint faces and of typical Jurassic aspect - - - 5

5. Shaly beds, seldom exposed, carrying oolitic limestone. Green or
sandy limestone of drab color - - - - - - 15

6. Rough weathering limestone, fine grained, cross-bedded and fissile,
carrying fossils - - : 2 = > . = . 5

7. Sandy limestone like that above, but irregularly bedded and resem-
bling sandstone; granular and saccharoidal in texture, carries shell
fragments - - - 2 - - - - - - 4

8. Irregularly platy, earthy-brown, gray limestone carrying shell
remains of Gryphea and Ostrea, weathering dark brown, rarely

granular - - - - - - - - - - 6
g. Marly shales and limestone, dove colored, carrying fossils noted in

following pages, seldom exposed, Gryfhea most abundant here - 30
10. No exposure, but débris of sandstone’ - - - 2 60

11. Ellis sandstone, variable, buff, platy sand rock; pink blotched at base
with occasional shells; cross-bedded purple-brown outcrop. It is

at the top a limestone full of black and white quartz sand grains

and forms a dark brown ridge - - - - - - - 12

This section gives the total thickness of the Jura for this
region at 184 feet, which is nearly double that of the Little
Rocky and Castle Mountain areas.

The fossils collected from the horizon mentioned above are :
Ostrea strigilecula White; Gryphea calceola var. nebrascensis M. &
H.; Wodiola subimbricata M.; Cucullaea haguet M.; Pleuromya sub-
compressa M.

WEED and Pirsson, Eighteenth Ann. Rept., U. S. Geol. Surv., III, p. 445.

258 W. N. LOGAN

Yellowstone Park.7—The thickness of the formation for this area
is placed at 200 feet. It consists of sandstones, marls, limestones,
and clays, and contains, according to Stanton,’ the following spe-
cies: Pentacrinus astericus M. & H.; Rhynchonella myrina Hall &
Whitf.; Rynchonella gnathophora M.; Ostrea strigilecula White ;
Ostrea engelmant M.; Gryphea planoconvexa Whitt.; Gryphea calceola
var. nebrascensis M. & H.; Lima cinnabarensis Stan.; Camptonectes
bellistriatus M.; Camptonectes bellistriatus var. distans Stanton; Camp-
tonectes pertenurstriatus Hall & Whitf.; Camptonectes platessiformts
White; Avzcula (Oxytoma) Wyomingensis Stan.; Pseudomonotis
Curta (Hall)?; Gervilha montanaensis M.; Gervillia sp. Stan.;
Modiola subimbricata Meek; Pinna kingt M.; Cucullaea haguet M.;
Trigonia americana M.; Trigonia elegantissima M.; Trigonia mon-
tanaensis M.; Astarte mecki Stan.; Astarte sp. Stanton; Tancredia?
knowltont Stan.; Protocardia shumardi M. & H.; Cyprina? Cinna-
barensis Stanton; Cyprina? iddingst Stanton; Cypricardia? haguet
Stanton; Pholadomya kingi M.; Pholadomya tnaequiplicata Stan.;
Homomya gallatinensis Stan.; Pleuromya subcompressa M.; Thracta
weedi Stanton; Thracia? montanaensis (Meek)?; Anatina ( Cer-
comya) punctata Stan.; Anatina (Cercomya) sp. Stan.; Neritina
wyomingensis Stan.; Lyosoma powelli White; Turitella sp. Stan.;
Natica sp. Stan.; Oppelia? sp. Stan.; Perispinctes sp. Stan.; and
Belemnites densus Meek and Hayden.

THE CANADIAN AREA

In the Queen Charlotte Islands Whiteaves3 noted the occur-
rence of the following species, which are common to the Jura of
the Interior: Pleuromya subcompressa Mk.; Astarte packardi White ;
Avicula (Oxytoma) mucronata Mk.; Gryphea calceola var. nebras-
censis M. & H.; Lyosoma powelli White ; Belemnites densus M.& H.;
Belemnites skidgatensis Whiteav.; Grammatodon inornatus Whiteav.;
Modiola subimbricata Mk.; and Camptonectes extenuatus Mk.

Although Whiteaves recognized the interior affinity of these
forms, he was inclined to put both groups into the Cretaceous

tU.S. Geol. Surv., Yellowstone Park Folio, 1896.
2U. S. Geol. Surv., Yellowstone Park Monograph, XXXII, p. 601, 1899.
3 Geol. Surv., Canada, Mesozoic Fossils, Vol. I.

EPICONTINENTAL SEA OF JURASSIC AGE 259

rather than the Jura. But the Jurassic age of these beds
is now sufficiently well established not to require further dis-
cussion.

Not only is this fauna represented in the islands just men-
tioned, but it occurs also on the continent at some considerable
distance inland. From fossils collected by G. M. Dawson on the
Iltasyouco River in British Columbia about Parallel 53° and
Longitude 126° West, Whiteaves" recognized the following spe-
cies: Pleuromya subcompressa Mk.; Pleuromya levigata Whiteav.;
Astarte packardi White; Trigonia dawsont Whiteav.; Modiola for-
mosa M. & H.; Gervillea montanaensis Mk.; Gryphea calceola var.
nebrascensis M. & H.; Grammatodon inornatus Whiteav.; Oleoste-
phanus loganianus Whiteav.

These fossils were found in the felsites and porphyrites of
the metamorphic rocks lying east of the Coast Range. They
contain species common to both the Queen Charlotte and the
Interior faunas.

From fossils collected by G. M. Dawson at Nicola Lake in
British Columbia Hyatt? determined the Jurassic age of certain
beds in that region lying above the Triassic. The fossils col-
lected are: Rhynchonella gnathophoria?; Pecten acutiplicatus Gabb ;
Entolum sp. Hyatt; Lama parva Hyatt.

Just north of Parallel 51°, near the east end of Devil’s Lake,
which is situated on the eastern border of the Front Range of
the Rockies, McConnell3 found an outlier of Jurassic which
contained the following fossils: Avicula (Oxytoma) mucronata;
Trigonia intermedia; Trigonarca tumida, Lerebratula, Ostrea, Camp-
tonectes, Lima, Cyprina, Ammonites, and Lelemnites. This locality
serves as a connecting link between the Montana area and the
localities to the west, as it is situated midway between the two.
The above-named group of fossils contains one species and a
number of genera common to the Interior and the Pacific Coast
deposits.

SEOG Git

2 Rept. of Geol. Surv., Canada, 1894, p. 51.

3 Rept. of Geol. Surv. Canada, 1896, p. 17d.

260 W. N. LOGAN

THE ALEUTIAN AREA

Grewingk* was the first to announce the occurrence of beds
of Jurassic age in Alaska. These beds were discovered at differ-
ent places along the Alaskan Peninsula and the Aleutian Islands.
From the distribution of these beds as mapped by Grewingk the
Alaskan Peninsula and the Aleutian Islands must have been
under water during Jurassic times.

In 1872 Eichwald? described an assemblage of fossils col-
lected from these same beds and correlated them with the
Northern Russia beds of the same age, but put both formations
in the Lower Cretaceous. Some fossils were collected from the
same region by Dall in 1883. These forms were described by
White,3? who after making a study of them and comparing them
with Eichwald’s descriptions, decided that the latter was wrong
in his assignment of the beds to the Cretaceous. He found them
to be closely allied to the Jurassic of Northern Russia. One
species, Aucella concentrica Fisher, he considers either identical
or only a variety of the Eurasian Jurassic form of that name.

Hyatt,‘ in speaking of these deposits, says: ‘‘ The fauna of
the Black Hills, acknowledged to be Jurassic by everyone but
Whiteaves, is in part apparently synchronous with that of the
Aleutian Islands and Alaska, as described by Eichwald and
Grewingk.”’

The position of these beds and the relation of the fauna with
the northern Eurasian fauna points clearly to an Arctic-Pacific
connection by way of the Bering waters during this epoch. More-
over we now have an almost continuous faunal record extending
from Alaska to southern Utah.

Conclustons.— An examination of the above sections will show
that the thickness of the Jura in the interior is not very great.
An average of ten localities gives a thickness of but little over

tRussian Kaiserl. Mineral Gesell., 1848-9.

? Geognostisch-Paleontologische Bemerkungen iiber die Halbinsel Mangischlak
und die Aleutschen Insel.

3 Bull. U.S. Geol. Surv. No. 4, 1884.
4Bull. Geol. Soc. Am., Vol. V, 1894, p. 409.

EPICONTINENTAL SEA OF JURASSIC AGE 261

two hundred feet. In fourteen localities the thickness is under
four hundred feet. These localities are scattered throughout the
length and breadth of the interior province. In all the areas for
which greater thicknesses have been recorded there are none in
which the entire thickness could, without question, be assigned
to the Jura.

The lithological character of the beds is much the same for
all areas. The formation consists everywhere of essentially the
same group of arenaceous clays, shaly marls, impure limestones
and sandstones. The order of succession of the beds implies
ever changing conditions of sedimentation. Thin beds of sand-
stone are overlain by thin beds of fossilferous clays, marls, or
limestones; and these in turn are followed by another similar
group.

The absence of any considerable thickness of limestone over
a large area indicates that for no great period of time were the
waters of the sea entirely free from clastic sediments. The
presence of cross-bedded sandstone and ripple-marked layers at
different horizons, the almost universal presence of Ostrea and
other shallow water forms, together with the stratigraphic and
lithologic characters just mentioned prove that the waters of the
sea were not of great depth; that the sea was not of the abysmal
type. It was not a sea comparable in depth to the Mediterranean
but was a shallow epicontinental sea. From the geographic dis-
tribution of the known Jurassic the outlines of this sea were as
indicated on the map’ accompanying this paper.

From the character and extent of the sea it may be assumed
that no extensive epeirogenic movement was necessary for its
inauguration, providing the antecedent topographic conditions
were favorable. Inthe northern part of the area there is evidence
that a considerable period of erosion preceded the Jura, as the
Red Beds are absent and the Jura rests on the Carboniferous.
This period of erosion may have been sufficient to reduce the
land area to approximate base level in which case a very slight
warping would have been sufficient to let the waters of this

«See p. 245.

262 WN. LOGAN

shallow sea in upon the continent. A very slight increase in the
capacity of the ocean basin would suffice to draw the water off
the continent at the close of the period. The increase in the
capacity of the ocean may have been accomplished by a slight
settling of the oceanic segment. The withdrawal of the waters
of the epicontinental sea was doubtless the initial step in the
movement which ended in the elevation of the Sierra Nevada
Mountains ; for the withdrawal took place at the close of the
Oxfordian stage or during the Corallian and according to Diller’
the orogenic movement which produced the Sierra Nevada and
Klamath Mountains took place at the close of the Corallian. If
these interpretations be logical ones we may assume that. it
required little or no bodily movement of the continent to pro-
duced either the inauguration of the Jurassic sea or its withdrawal
from the continent. It may be asserted further that there is
nothing connected with its history which is inimical to the doc-
trine that the continent had in general its present outline during
Jurassic times and that the waters of the submerged portions
were of an epicontinental nature.

‘The writer’s study of the faunal conditions in the field has
led him to the opinion that only one fauna is to be recognized
in the Jurassic deposits of the interior province. A comparison
of the fossils collected from the different areas just discussed
serves to strengthen the opinion. Everywhere the formation is
characterized by about the same group of fossils, of which the
more characteristic ones are: Lentacrinus astericus, Belemnites
densus, Camptonectes bellistriatus, Pseudomonotis curta and Cardi-
oceras cordtforme. These forms all existed contemporaneously.

Stanton? discusses the view expressed by Hyatt3 that more
than one Jurassic fauna may be represented in the Interior and
arrived at the following conclusion: ‘‘the stratigraphic relations
and the geographic distribution of the marine Jurassic of the
Rocky Mountain region are in favor of the idea that all of these
deposits were made contemporaneously in a single sea.”

™ Bull. Geol. Soc. Am. Vol. IV, p. 228.
2U.S. Geol. Surv. Yellowstone Park Monograph XXXII, 1899, pp. 602-604.
3 Bull. Geol. Soc. Am. Vol. III, 1892, pp. 409-410.

BPICONITINENIAL SEA OF JURASSIC AGE. 263

This fauna according to Hyatt belongs to the Oxfordian stage
of the Upper Jura or Malm. In the Taylorville series of Cali-
fornia he recognized the Callovian, the Oxfordian and the
Corallian stages of the Upper Jura. Butas has been stated above
none but the middle stage has been recognized in the Interior.

Relation of the interior fauna to the northern eurasian fauna.—
The discovery of beds of Jurassic age in the interior was first
announced by Meek* in 1858. In correlating these beds with
the Jura of the Old World he says: ‘‘The organic remains found
in these series present, both individually and as a group, very
close affinities to those in the Jurassic epoch in the Old World ;
so close indeed, that in some instances, after the most careful
comparisons with figures and descriptions, we. are left in doubt
whether they should be regarded as distinct species, or as vari-
ties of well-known European Jurassic forms. Among those so
closely allied to foreign Jurassic species may be mentioned an
Ammonite we have described under the name of Ammonites corat-
formis which we now regard as probably identical with Azmmonites
cordatus of Sowerby; a Gryphea we have been only able to dis-
tinguish as a variety from G. calceola Quenstedt; a Pecten,
scarcely distinguishable from Pecten lens Sowerby ; a Modiola,
very closely allied to M. cancellata, of Goldfuss; a Belemmnite,
agreeing very well with Bb. excentricus.”

Since the publication of the above statements by Meek the
paleontology of the European Jura has been more completely
worked out and some of the faunas, particularly that of north-
ern Russia, are found to have still closer affinities to the Ameri-
can interior fauna. The Jurassic faunas of America have also
received many additions at the hands of the American paleon-
tologists Gabb, Hyatt, Meek, Smith, Stanton, White, Whiteaves,
and Whitfield. All of these studies have tended to strengthen
the opinion just expressed.

The following comparison of forms which are so closely
allied as to deserve, in many cases, to be called varieties of the
same species will serve to show the close affinity of the interior

* Geological Report of the Exploration of the Yellowstone and Missouri Rivers.

264 W. N. LOGAN

American fauna to the fauna of northern Eurasia: Belemnites
panderanus d’Orb. and Lelemnites densus Mk.; Astarte duborsianus
d’Orb. and Astarte pakardi White; Avicula volgensis d’O. and
Avicula mucronata Mk.; Pentacrinus scalaris Goldf. and Penta-
crinus astericus M. & H.; Gontomya dubois d’Orb. and Goniomya
montanaensis Mk.; Gryphea calceola, Quen. and Gryphea caceola
var. nebrascensis Mk.; Cardioceras cordatus Sow. and Cardioceras
cordiforme Mk. The faunas taken as a whole exhibit the close
relationship in a much more forcible manner than the comparison
of a few species.

This northern Eurasian, or Cardioceras fauna is thought to
have had its origin on the northern shores of the Eurasian con-
tinent, and to have migrated from there to American waters.
This assumption is based on the sudden appearance of the
fauna in America and its close affinities with older Eurasian
faunas. The present geographic distribution of the fauna
indicates a northern connection.

A later Jurassic fauna, the ducella fauna, probably had its
origin in the north and migrated to Pacific waters. This fauna,
however, did not reach the interior province of America as the
waters of the epicontinental sea had been withdrawn before its
appearance. This later migration extended along the Pacific
coast as far south as Mexico.

Both of the faunas just mentioned belong to the Upper Jura,
but the Lias and Middle Jura are also represented in the Cali-
fornian province. The Upper Jura, however, represents the
maximum encroachment of the ocean on the American con-
tinent as well as on the Eurasian continent. It also marks the
maximum expansion: of marine life, induced doubtless by
increased feeding grounds.

Connection of the sea with the ocean.— The question as to where
the interior sea had its connection, or connections, with the
ocean is important in estimating the extent of the submergence,
That the sea had a Pacific Ocean connection there seems no
longer room for doubt. The occurrence in the Queen Charlotte
fauna of so many species common to the interior places the

EPICONTINENTAL SEA OF JURASSIC AGE 265

question beyond controversy. That there was communication
between the Arctic and the Pacific is supported by the presence
of Arctic species in the Pacific fauna. From the distribution of
the Jurassic sediments as given in the preceding pages it may be
asserted with a measurable degree of confidence that the con-
nection between these two bodies of water was during Jurassic
times as it is today by way of the Bering waters. As the pres-
ence of Jurassic deposits on the Alaskan Peninsula and the
Aleutian Islands testify to the submergence of those areas, it
may be assumed that communication between the two oceans
was somewhat freer than at present.

The question which is now brought to mind is whether the
interior sea had any other connection with the ocean. The
character of the fauna excludes any hypothesis favoring a
southern connection either with the Gulf of Mexico or the
Pacific. If there had been such a connection a southern facies
would be expressed in its fauna. Such evidence is entirely
absent. The evidence against any other Arctic connection 1s
largely negative, but as such is measurably strong. The inves-
tigations of American and Canadian geologists have failed to
bring to light any Jurassic deposits in the North aside from
those already described, although approximately the whole area
where we should expect to find them has been gone over.

McConnell,? who made geological investigations in Athabasca
and along the Finlay and Porcupine Rivers, found Cretaceous
beds resting on Devonian and Carboniferous strata. The interval
of time which elapsed: between the Carboniferous and the Lower
Cretaceous is not represented in this region.

Spurr? found the same conditions to.obtain for the Upper
Yukon region of Alaska and the neighboring British territory.
The Lower Cretaceous rests on Devonian or Carboniferous rocks.
As before stated this evidence is merely negative. Jurassic
rocks may have been deposited and afterwards cut away. But,

* Geol. Survey of Canada, Vols. V and VII.

2Geol. of the Yukon Gold District, U. S. Geol. Sury., Seventeenth Ann. Rept.,
1897.

266 W. N. LOGAN

in that case, we should expect to find remnants of the former
beds unless it be assumed that a long interval of time preceded
the deposition of the Lower Cretaceous. Paleontologic and
stratigraphic evidence is not in harmony with this assumption.
The Lower Cretaceous beds of California which are but slightly
unconformable with the Upper Jurassic, having a closely related
fauna, are correlated with the Lower Cretaceous of the region
under discussion.' die

In many places in the interior region the Lower Cretaceous
rests conformably on the Jurassic. This tact has been fully
brought out in the preceding pages. It cannot be affirmed that
the interior sea first had its connection with the Arctic and then
gradually spread its waters farther and farther west until it united
with the Pacific. For if this were true we should find in the
interior first a fauna composed wholly of. northern species, fol-
lowed later by a fauna containing both Arctic and Pacific types.
But no such conditions find expression in the faunal relations of
the interior. Only one fauna exists in the interior.

There exists at present no evidence which will support the
view held by Neumayr,? that the whole of Alaska and all of that
portion of British America lying north of the interior Jurassic
area of the United States was submerged during this epoch. All
that can be asserted positively is that the Aleutian Islands and
Alaskan Peninsula, in part at least, a narrow margin along the
Alaskan coast and a wider area in California and Mexico was
under water, while an arm of the Pacific extended in upon the
continent from the region of the Queen Charlotte Islands.3

Lack of communication between the provinces —The Jura of Cal-
iforniaand Nevada contains a fauna which is very different from
that of the interior, although the faunas are contemporaneous.
To explain the difference between the two faunas Neumayr
assumed that that they belonged to two distinct climatic prov-
inces. He assumed that the interior fauna was a Boreal fauna

XSpurr, 15 Cpls.

2See map p. 267, copied from Erdgeschichte, p. 336.

3See map p. 245.

267

EPICONTINENTAL SHA OF JURASSIC AGE

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268 W. N. LOGAN

which lived in an arm of the Arctic Ocean, and that the Cal-
ifornian fauna belonged to another climatic province, the north
temperate.

In a recent discussion of the subject Ortman* has shown
very conclusively that the faunal differences of Jurassic times,
so far as the Eurasian continent is concerned, were not due to
climatic zones. The distribution of the interior or Cardioceras
fauna favors this view for the North American continent, The
Cardioceras fauna is found distributed through a range of lati-
tude extending from 37° to 80° north. Its southernmost exten-
sion is not as placed by Neumayr in the neighborhood of 46°,
but is at least as far south as 37°, and is found in approximately
the same latitude as the Californian province. Moreover, the
later (for the American region) Jurassic fauna, the Aucella, has
been reported from Mexico.?, The Aucella fauna also had its
origin in northern Eurasian waters. Its geographic range was
from 80° north to 25° north. This means an extension of Neu-
mayr’s Boreal province to within 25° degrees of the equator!
The great geographical range of this fauna indicates that there
was little or no climatic restriction to its migration. In so far
as the evidence can be deduced from the geographic distribu-
tion of the American Jurassic faunas the climate of the period
may be said to have been more uniform than it is today.

The above facts are perhaps sufficient to show the weakness
of the climatic-zone hypothesis. It now remains to suggest an
alternative line of investigation. In seeking for the causes for
the want of communication between the provinces it may be
possible to draw some analogy from the faunal and topographic
conditions as they exist today on the Pacific coast. There are
at present on the Pacific coast, according to Fischer,3 two
faunal provinces, the Aleutian, corresponding in position to the
Queen Charlotte of Jurassic times, and the Californian, corres-
ponding to the Jurassic province of the same name. The line

™ Am. Jour. Sci. Vol. I, 1896, p. 257.

2 Nitikin, Neus Jahrb. Min. Geol. Pal., 1890, II, p. 273.

3 Manuel Conchologie.

EPICONTINENTAL SEA OF JURASSIC AGE 2609

separating these two provinces is placed in the vicinity of Van-
couver Island. The faunal interrelations of these two provinces
are as follows: Of seventy-eight genera occurring in the two
provinces nine are common to both ; of one hundred and four
species six are common to both; andof ten circumpolar species
which have reached Vancouver Island and Puget Sound only
four occur in California, and but one in Lower California. '
From these conditions it will be seen that communication
between the two provinces is almost, if not quite, as thoroughly
prohibited now as it was during Jurassic times. The question
which now arises is what restricts communication between the two
provinces at present? It cannot be said to be due to climate
alone, for why in that case should the circumpolar species be
found so far south? And why should they all be found in Puget
Sound and not be found farther south? This seems to be an
exception to the general rule that the climatic provinces of the
present time are connected by transition zones. For the line of
demarcation is moderately sharp.

Aside from the matter of climate there are two physio-
graphic conditions which may be operative. The first of these
lies in the extreme narrowness of the sumerged shelf lying to
the north and west of Puget Sound. This shelf teeming with
organisms already well established offers small inducement to
migratory forms. And only the more hardy forms would be
likely to survive the struggle for existence under such circum-
stances as are here postulated. Thus the change of species
from one province to the other is necessarily slow.

There are good reasons for believing that throughout the
Mesozoic era these topographic conditions of the Puget Sound
region were much as they are at present. During the Horse-
town epoch the Pacific shoreline, although it lay a considerable
distance east of the present shoreline in California and Oregon,
very closely approximated it in the Puget Sound area. The
Chico also had a very restricted epicontinental area at that
point as the Chico shoreline extended only to the eastern coast
of Puget Sound. In Californiaand Oregon, however, its eastward

270 W. N. LOGAN

extension was far beyond that of the Horsetown.* The Jurassic
beds do not occur in the Puget Sound region, and as they under-
lie the Horsetown elswhere, it is evident that the Jurassic. shore-
line at this point must have been at least as far west as the
present shoreline.

A second cause for the lack of communication between the
“two provinces may lie in the position of the ocean currents.
The Californian currents coming from the west along a line lying
between the Queen Charlotte Islands and the island of Vancou-
ver turns south at some notable distance from the coast, and
after passing Vancouver bears toward the coast and flows.on
along the Californian province. The North Pacific current which
flows east closely parallel to the Californian bears northward
before reaching the Queen Charlotte Islands. Neither of these
currents, since they do not cross the line separating the two
provinces, is effective in establishing communication by carrying
embryonic or larval forms which might under different cir-
cumstances be brought within their reach. This same distribu-
tion of ocean currents probably held during Jurassic times, as in
general, the large land masses in this region, at least, had their
present distribution.

The attractive feeding ground furnished by the epicontinental
sea doubtless exerted its influence to prevent southern migra-
tion. When later the waters were drawn off the continent the
accumulation of the great numbers of organisms on the coast
may have been sufficient to force the migration southward. Or
perhaps the interval of time was sufficiently long tor some of
these northern species to have forced their way into the Califor-
nian province during later Jurassic time. In either case we
would have in the Upper Jurassic faunas of California a north-
ern element, and this seems a wel!-established fact. Neverthe-
less, since this Upper Jurassic fauna has been reported from
Mexico it is evident that communication was freer between the
two provinces after the withdrawal of the waters of the epiconti-
nental sea. And it is very likely that the movement which caused

tSee map p. 271.

~

x=

w-wer 2-2 lS.

Fic. 3.—Map showing the approximate position of the Chico (C) and Horsetown
(H) Shore lines (after Diller and Stanton).

272 W. N. LOGAN

Fic. 4..-Map showing the position of the North Pacific Currents and the
approximate outline of the Jurassic Sea.

EPICONTINENTAL SEA OF JURASSIC AGE 27:3

the withdrawal also slightly depressed the barrier between the
provinces.

Final conclusions.—It now remains to state briefly, in review,
the conclusions to which the lines of investigation have led.
They are as follows: 1. The Jurassic formation of the interior
province of North America was not deposited in a body of
water of even moderate oceanic depth, but in a shallow epiconti-
nental sea.

2. This sea had but one connection with the ocean and that
connection was with the North Pacific in the Queen Charlotte
Island region ; in general the outlines of the sea were as indi-
cated on the map accompanying this article.

3. There was a connection, during this epoch, between the
Arctic and Pacific by way of the Bering waters, and by this
means circumpolar and Pacific faunal communication was estab-
lished.

4. The Jurassic deposits of the interior contain but one fauna
and if more than one period of time is represented it is not indi-
cated by a change in the fauna.

5. The fauna of the interior is closely allied to the Cardio-
ceras fauna of northern Eurasia.

6. Physiographic rather than climatic condition restricted
communication between the Californian and interior provinces.

7. Nothing connected with the history of this Jurassic sea or
its faunal relations is inimical to the view that during this
epoch the North American continent had, in general, its present
outline.

8. The geographic distribution of land and water, as postu-
lated by Neumayr for this period, is not supported by the facts,
in so far as the North American Jura is concerned.

W. N. Logan.

Jet ION TEOIRILAUL

GroLoaists heartily participate in the satisfaction which
astronomers justly feel over the great mass of accurate data
which favorable conditions and their own zeal and skill enabled
them to gather from the recent solar eclipse. Geologists offer
their cordial felicitations not only as fellow scientists rejoicing in
the common advancement of science for its own sake, and for its
influence on the world, but because they are themselves con-
cerned in the solution of the solar problems. Especially are
they interested in those questions of the sun’s constitution and
internal activities which bear upon his sources of heat, present,
past, and future; for these vitally touch the limitations of geologic
history. It is impossible, therefore, for historical geologists to
be indifferent to the results of any investigation that promises
to throw light upon the thermal endurance of the sun.

The central subject of interest in the recent observations,
the constitution of the corona, may seem quite remote from any
geologic relationship, but, as in so many other cases in the his-
tory of science, light upon dark problems may come from an
unexpected source. It is not beyond the limits of speculation
to conceive that the corona may prove to be the very phenom-
enon that will point the way to a revised estimate of the thermal
possibilities of the sun and thus to a revised measure of its past
duration and of the age of the earth as one of its dependencies.
Some hint of the possibilities may be found in the logical
sequences of one of the alternative working hypotheses relative
to the coronal nature. If the conception that it is formed of
extremely attenuated matter driven away at great velocities, after
the analogy of the tails of comets, should be substantiated, it will
necessarily be followed by the problem of the origin of such
attenuated matter. In the case of comets such supposed matter
may be assumed to be simply an accessory constituent brought
in from distant space and deveioped by approach to the sun —
and soon exhausted in the case of captured comets—but such a

274

EDITORIAL 275

hypothesis does not seem well fitted to the sun itself in this late
stage of its history. The alternative conjecture that the attenuated
form of matter is developed in the sun by the extraordinary agen-
cies operative there must obviously be entertained until disproved,
and the recent investigations of J. J. Thompson and others with
reference to the extremely attenuated ionization of terrestrial
gases under certain conditions render such a hypothesis less
highly improbable than it would have seemed under the domi-
nance of the inherited doctrine of the indivisibility of the atom.

A speculation which involves the notion of the divisibility of
the atom involves also that of the divisibility of the internal
energies of the atom and their possible transformation into
radiant energy,and hence a possible source of heat of unknown
and, at present, quite incalculable amount.

So too, a speculation which assumes that the corona is
radiated matter involves also the conception of loss of sun’s
substance if the velocity of radiation be as high as that attributed
to the conjectural matter of comets’ tails; and if this loss of
matter in the course of great secular periods becomes appreciable,
it may require a reconsideration of the data upon which estimates
of the sun’s heat are based and also of a revised consideration
of the former distances of the planets.

Now such an attenuated chain of hypotheses, each dependent
on an antecedent hypothesis of uncertain verity, may be alto-
gether too unsubstantial to have any appreciable value of the
positive sort, other than as the antecedent of investigation, but it
may have the negative virtue of helping to keep open the question
of the sum total of the sources of the sun’s heat and its possible
duration in the past and the future. And so possibly may also the
logical sequences of the alternative coronal hypotheses. The
Helmholtzian theory assigns a source of heat of such competency
that it cannot be proved not to be the sole essential cause by any
measurements of the sun that can be made now, or probably in
the near future, and hence it satisfies the immediate demands of
astronomical science, however inadequate it may be to meet
the natural interpretations of geological and biological data;

2710 EDITORIAL

but it may be conjectured that when the history of the stellar
system shall become as serious and substantial a subject of study
as the history of the earth now is, astronomers will find at least
as great need for long lapses of time and for the secular endur-
ance of thermal states as do the geologists and biologists.
Meanwhile all solar inquiries are subjects of acute interest in
common and the achievements of May 28 are matters of heartiest
congratulation. M,C. CG,

Tue George Huntington Williams Memorial Lectures, inaug-
urated in 1897 by Sir Archibald Geike, have been continued this
year by Professor W. C. Brogger, of the University of Chris-
tiania, who delivered at the Johns Hopkins University two lectures
on The Principles of a Genetic Classification of the Igneous
Rocks, and five lectures on The Late Geological History of
Scandinavia, as shown by changes of level and climate in
southern Norway since the close of the glacial epoch. His
long and thorough investigation of the igneous rocks of the
Christiania region, so varied in character, well preserved and
finely exposed, has qualified him to speak with authority upon
the subject of their genetic relations, and renders his judgment
upon the general problem of the classification of igneous rocks
of the firstimportance. Until the text of these lectures has been
published, it will not be in place to discuss the conclusions
enunciated by Professor Brégger. The lectures on The Late
Geological History of Scandinavia were based upon recent field
studies of the glacial phenomena of that region. In addition to
their special scientific value, they illustrate the remarkable ver-
satility and energy of Professor Brogger, whose substantial con-
tributions to the paleontology and stratigraphy, the mineralogy
and petrology of the Christiania region have already awakened
the admiration of his fellow workers.

Professor Brogger also delivered his lectures on the Genetic
Classification of Igneous Rocks at the University of Chicago to
an appreciative audience of students and geologists, who assem-
bled from various parts of Illinois and from Michigan, Wis-
consin, and Minnesota. Je Pane

REVIEWS

A Preliminary Report on the Geology of Lowstana. By GILBERT D.
Harris, geologist in charge, and A. C. VrEarcu, assistant
geologist. Made under direction of State Experiment Sta-
HON) batonmNouce seam Vim Cr Stubbs Eh De director:
[ No place or date. |

This report is divided into three sections: I, Historical Review ;
II, General Geology, and III, Special papers.

In view of the important disagreements between the earlier writers
upon Louisiana geology and the authors of this volume the historical
review with which it opens is especially important and interesting.
The full meaning of this review is only clear after one reads the second
part and some of the third part of the volume. The lowest horizons
represented are Cretaceous, and the earlier determination of these beds
séems to have been based upon the occurrence of a single species,
Lixogyra costata. The present survey has been able to get together a
a fairly good representation of the Cretaceous fauna of the state (p.
292-297).

The Mansfield of Hilgard, which was referred by Hopkins to the
Jackson (p. 29-35) at the top of the Eocene, turns out to be Lower
Lignitic Eocene (pp. 64-73), a horizon not hitherto known to exist
in Louisiana. The conclusions reached in regard to the Cretaceous
give us a new view of the general geology of the state. The dips and
many other facts cited “indicate northeast-southwest local folds paral-
lel to the old shore lines,” rather than a northwest-southeast mountain
chain (p. 62.) Of the Vicksburgh beds which some of the earlier
writers thought they had found between Red River and the Sabine,
Professor Harris says ‘‘we have found no trace of Vicksburg deposits
west of Red River” (p. 90).

A part of the second section of the report is devoted to Economic
Geology, and under this head are given valuable data regarding the
salt, sulphur, and clay deposits of the state. Among the special
reports are several of more than unusual interest. One of these is Mr.
Veatch’s paper upon ‘‘The Shreveport Area.”’ Under this head he

277

278 REVIEWS

treats at length “the great raft’—a subject of deep interest to geolo-
gists(pp. 160-173). He explains its origin, method and rates of growth
and decay, and describes the effects of such accumulations and of their
removal. He makes some interesting observations upon the lakes of
the area, which he classes as: (1) cut-off or horseshoe lakes; (2) lakes
of enclosure ; and (3) raft lakes. The ‘raft lakes,” it seems, have been
attributed to a sinking of the land, but Mr. Veatch thinks they have
been formed by the choking up of the former drainage by the accumu-
lation of drift timber in old stream channels (p. 188). The activity of
geologic agents in regions of such sluggish drainage has evidently not
been realized hitherto, for here in a region at or close to its base level
“Lakes have been formed and destroyed; streams have .been formed
and abandoned; waterfalls produced to destroy themselves; new
streams formed out of parts of the beds of old ones and temporary
reversals of the drainage systems have been affected” (p. 154). The
articles on the Five Islands (pp. 213-262) is by far the most thorough
and satisfactory that has yet appeared upon the remarkable salt depos-
its of Louisiana. The investigation of the clays by Dr. H. Ries is a
valuable piece of work done by one of our best authorities on the
subject. :

Papers of paleontologic interest are given in the third section by
Professor Harris upon the Natchitoches area, and upon the Cretaceous
and Lower Eocene faunas of Louisiana. These papers are illustrated
by seven beautifully prepared plates. Professor Harris also contributes
a paper upon meridian lines, and another upon road making. This
last subject is entitled to the serious attention of the people of Lou-
isiana. That the geologists are unable to make the most of their time
because of the bad roads of the state is to be regretted, and the geolo-
gists have our sympathy, but when many of these roads become such
quagmires for several months of the year that traffic over them comes
to a dead standstill, it is a matter that more or less seriously affects the
prosperity and happiness of the entire population.

Arthur Hollick contributes a well illustrated and valuable article
upon the Lower Tertiary plants from the northwestern part of the
state (pp. 276-288, and 16 plates).

It is pleasant to see that Dr. Stubbs, the director of the State
Experiment Stations, under whom the geological survey is being made,
appreciates the fitness, ability, and enthusiasm of the men who are doing
the work. Indeed it would have been difficult if not impossible to have

RE VIE VUZS 2/19

found a man better fitted than Professor Harris to take charge of the
study of Louisiana geology. ‘The problems of the stratigraphy of the
state can be attacked successfully only by a careful study of the fossils.
The promptness with which the report has been published is one of its
many virtues. The work was begun in November 1898, and Professor
Harris’ letter of transmission is dated November 1899. Such prompt-
ness, however, sometimes has its disadvantages. It is doubtless respon-
sible for several important typographical errors, for the awkward
title-page that gives neither date nor place of publication, and for the
unfinished condition in which the maps appear. Perhaps it is just as
well that the geological map accompanying the report is credited to
no one, for to no one is it a credit. With the exception of the maps
the volume is well printed and tastefully bound; and the defects we
may find in the mechanical part of the work are very small matters
compared with the valuable contributions to science contained in the

report.
Joun C. BRANNER.

On the Lower Silurian (Trenton) Fauna of Baffin Land. By
CHARTES SCHUCHERD, Proce Unis) Nata viuse Vol) XOCy pp:
143-177, plates XII-XIV.

Any addition to our knowledge of the fossil faunas of the arctic
regions is received with special satisfaction by those who are interested
in the broader problems of palzontology, in which the facts of geo-
graphic distribution are of special moment. The present paper by Mr.
Schuchert is one of the most important of such contributions to be
found in our literature. It is devoted to the description and discussion
of more complete collections of fossils from Sillman’s Fossil Mount
at the head of Frobisher Bay, than have previously been secured from
that locality. Seventy species of fossils are recorded, eighteen being
described as new. ‘The fauna shows strong affinities with the Trenton
fauna of the United States, especially with the fauna of that age as it is
known,in Minnesota, a large proportion of the species being common
to the two regions.

The Trenton fauna has been recognized at various localities in the
arctic regions, the strata containing it always resting unconformably
upon the old crystalline rocks. No other Ordovician fauna has been
recognized in the whole region save at one locality, on Frobisher Bay,

280 REVIEWS

where a few species indicating a fauna of Utica age have been collected.

In general the Trenton beds are followed immediately by strata con-

taining a Silurian (Upper Silurian) fauna of Niagara or Wenlock age.
STUART WELLER.

The Glacial Palagonite-Formation of Iceland. By Hevei Pyjeturs-
son, Cand. Mag. Copenhagen. The Scottish Geographical
Magazine, May 1900, Vol. XVI, No. 5.

This appears to be a very important contribution to the history of
Pleistocene glaciation. It opens up a new and very promising field,
whose data are peculiar because of their association with volcanic phe-
nomena. The author presents in much detail, and with apparent care and
discrimination, evidence of glacial formations antedating the so-called
“‘preglacial”’ lava flows, as well as others interstratified with the lava
flows. After twenty-two pages devoted to description of details, illus-
trated by figures, the author draws the following important conclu-
sions :

I shall not be surprised if this account of the occurrence of glacial depos-
its and striated rock surfaces in connection with the ‘‘ palagonite-formation”’
of Iceland is received with incredulity. For myself, I could hardly believe
the evidence when | first encountered it, and tried to explain it in every pos-
sible way other than by glacial action. but the glacial origin of the ‘“brec-_
cias’’ could not be gainsaid. Not only did they present a characteristically
morainic aspect, but they yielded numerous well striated stones, and in places
were found to be resting upon grooved and striated rock surfaces. If the
observations I have here recorded be accepted as fairly trustworthy, we can-
not avoid the conclusion that glacial deposits, hitherto unrecognized as such,
are largely developed in Iceland, or at all events in that part of the island
which I have critically examined and referred to in these pages.

As I have had only a glimpse, as it were, into this very promising field of
glacial research, I shall not attempt to deal with the glacial succession in Ice-
land. That must be left for future investigations to determine. Nevertheless
there are several conclusions which seem to me obvious enough. Of these
the most important, in my opinion, is that which has reference to successive
glaciations. The facts advanced show that Iceland has experiencéd more
than one glaciation before the ejection of the doleritic lavas and their subse-
quent smoothing and grooving by ice. How many separate glaciations the
morainic breccias bear witness to is uncertain. But the repeated occurrence
of four separate sheets or beds of morainic breccia seems to render it not

improbable that there have been just as many separate glaciations during the
>

REVIEWS 281

accumulation of the so-called palagonite formation. Even if we discard the
evidence furnished by the lowest breccias (in which, it will be remembered,
that notwithstanding their morainic aspect, no striated stones occurred), we
have still the overwhelming evidence of glaciation supplied by the higher
morainic breccias. But whether these indurated ground moraines represent
three, four, or more glaciations, one or other of them must represent the
epoch of maximum glaciation in Europe. The glaciation which left the older
system of markings on the dolerite of Stangasfjall is, of course, of later date
and may possibly represent the Mecklenburgian stage (Geikie) of northern
Europe, and the first postglacial stage of glaciation of the Alps (Penck). It
seems more than probable that a change of. climate, corresponding to that
which in the Alps depressed the snow line about 3000 feet, would bring
about the total glaciation of Iceland. Indeed, a much less important change
in the climatic conditions would suffice to do this. It is therefore quite
possible that the younger system of striae marking the surfaces of the doler-
ites may be contemporaneous with that readvance of cold conditions which
produced the local glaciers of the “Lower Turbarian stage”’ of Scotland, ,
and those of the “Second postglacial stage” in the Alps.

[The second striated horizon in the moraine of Sudurnes (if it be not a
striated pavement) may possibly indicate a third “post-doleritic”’ glaciation,
but until additional evidence be forthcoming, this isolated observation must
be left out of consideration. ]

So far as I know, all that has been written on the glacial period in Ice-
land refers to the minor glaciations which supervened after the ejection of
the doleritic streams of lava. I say minor glaciations, even although the
country appears during those stages to have been totally ice-covered. But
the mass of the “ palagonite-moraines”’ is so very much greater than that of
the loose accumulations of the later glaciations, that we may reasonably infer
that the former are products of much greater ice-sheets. Moreover, the con-
ditions of erosion and accumulation during successive glaciations seem to
have differed at the same localities. Further, when we remember that the
whole region throughout which the palagonite-formation occurs, has been
extensively fractured and consequently has experienced many subsidences —
and when we reflect that all these important deformations of the land surface
took place subsequent to the accumulation of the uppermost morainic brec-
cias, we are led to suspect that the area over which the older glaciations pre-
vailed may have considerably exceeded that which now exists. Probably
conclusive evidence on this point may be obtained by studying the directions
of the oldest glacial striae all over the country, and more especially in the
north.

It would probably also be of great interest to determine the relations of
the Pliocene shell-beds near Husavik, North Iceland, to the “‘ tuff- and brec-
cia-formation.”” As I have obtained a grant from the Carlsberg Fund,

282 REVIEWS

Copenhagen, to enable me to continue these investigations, | hope to do so
on the lines here indicated.

About 5500 square miles of the total area of Iceland are at present
covered with glaciers. The country, therefore, would seem to be in a
state of glaciation comparable to that obtaining in Scotland during the fourth
glacial epoch as defined by Professor Geikie. Now, if Iceland were to be
once more totally glaciated, should we term that final ice-invasion a separate
stage of glaciation; or merely an oscillation of the existing glaciers? Would
the present inhabited condition of Iceland be considered an interglacial
epoch, or merely a stage of temporary glacial retreat ?

Such considerations must be kept in view when we are discussing whether
the old ground moraines described in this paper have been laid down by an
oscillating ice-sheet or during separate glacial epochs.

In Burfell two bottom-moraines are separated by 150 to 200 feet of
basalt, on the striated surface of which the upper moraine reposes. Possibly,
however, that basalt does not mark the lowest interglacial horizon.

To the next succeeding interglacial horizon probably belong the conglom-
erates of Stangarfjall, Bringa, and Hagafjall, which are supposed to be of
fluviatile origin. Perhaps also the columnar dolerite of Stangarfjall should
be included here. The existence of those conglomerates at such heights and
so far inland suggests at least a very considerable oscillation of the ice-sheet.
Moreover, we must not forget that the conglomerates in question are buried
underneath masses of various volcanic products. [While some of the old
gravel beds may well represent old river channels, in other places, as in
Hagafjall and Bringa, they had more the character of lacustrine deltas or
cones de aéjection. |

The next interval between two glaciations is that marked by the so-called
‘‘preglacial dolerites’’ which henceforward cannot claim to be more than
interglacial. ‘At the time these preglacial lava beds were laid down, the
country had pretty much the same essential contours that it has at present.” *
But when the uppermost of the “‘ palagonite-moraines”’ (as in Berghylsfjall
and Hagafjall) were laid down, the relief of the country, as we have seen,
differed greatly from that which now obtains. In the interval of time that
separates these morainic breccias from the eruption of the later lavas, the
most radical changes in the contours of the country had been effected, chiefly
perhaps by subsidence. The southern lowland of Iceland cannot date farther
back than this interglacial epoch.

It is not improbable, indeed, that the essential contour lines or surface
features of the whole island, so far as these are older than the later outflows
of dolerite, came into existence during this interglacial epoch. We cannot
tell at what particular stage the later dolerites were erupted, but we know

t Thoroddsen, Explorations etc., p. 55.

REVIEWS 283

that the changes of relief which were effected during the interglacial stage in
question were very much greater than those which have taken place since the
outflow of the doleritic lavas. And yet these lavas have been glaciated more
than once, and we do not know how long they had to wait for their first gla-
ciation.

We seem therefore justified in coming to the conclusion that the two gla-
ciations in question have not been the result of comparatively insignificant
oscillations of an ice-sheet, but were really separated by a protracted period.
The very occurrence indeed of the interglacial streams of lava over such
great areas suffices to show how extensively the ice-sheet melted away. It
seems to me highly probable that @// the so-called “ preglacial”’ lavas are in
reality interglacial.

Furthermore, the evidence leads to the inference that the time which has
elapsed since the last ice-sheet disappeared from the southern lowland of
Iceland is very short as compared to the interglacial epoch that intervened
between the first of the glaciations experienced by the dolerites and that next
preceding it.

Whether the supposed marine deposit which underlies the glaciated lava
on Tungufljot dates back to the closing stages of the interglacial epoch just
mentioned, or whether it ought rather to be ascribed to an interval separating
the two glaciations which are represented by the two systems of striae upon
the surfaces of the later dolerites, future investigations must be left to deter-
mine.

No doubt many additional conclusions are suggested by the observations
recorded in this paper, but I do not care to consider these at present. As
already stated, the chief object of this paper is to point out that there exists
in Iceland much hitherto unsuspected evidence of former glacial action. I
am indeed sanguine enough to think it not improbable that the records of the
glacial period have been more fully preserved here than elsewhere. For it is
obvious that the conditions for the protection and preservation of glacial
deposits have been with us somewhat exceptional. While in other lands,
free from volcanic activity, each succeeding ice-sheet has partly destroyed
and partly covered up the deposits of its predecessor, in Iceland the moraines
have been greatly sheltered by the products of volcanic eruptions which over-
lie them. Moreover, crustal movements have contributed directly toward the
same end by placing the old moraines beyond the reach, as it were, of suc-
ceeding glacial invasions. Not improbably, too, some rocks of the “‘tuff- and
breccia-formation”’ may be due to the direct interaction of volcanic and gla-
cial forces.

To this is added the discussion of some points of a more special
and local nature. It is gratifying to learn that the investigation is
likely to be continued. die (COGS

284 REVIEWS

Fossil Flora of the Lower Coal Measures of Missouri. By Davip
Wuite. U. S. Geological Survey, Monograph XXXVII,

468 pp., 1900.

The coal floras are always of great interest. The present contribu-
tion is the most important that the central-West has seen since the
appearance of Lesquereux’s classic work of a quarter of a century ago.
The title of the volume does not, however, express the real scope of
the work. Most of the forms come from a single locality, near
Clinton, in Henry county, Missouri, and from a single horizon— the
Jordan coal. ‘The latter is the lowest workable coal seam in the dis-

trict and is only about roo feet from the base of the Coal Measures. -

While the greater part of the monograph is taken up with the
minute descriptions of species, and discussions of the biological rela-
tionships of these, the chief interest to the stratigraphical geologist is
centered in the data furnished for broad correlations.

Regarding the probable stage of the lower coals of Clinton in east-
ern sections, Mr. White says: “If we take Henry county, from which
most of our evidence, both stratigraphic and paleontologic is drawn,
as the stratigraphic type of the base of the Coal Measures of the state,
and assume that the conditions are constant along the margin of the
coal field in other counties, the evidence of the fossil plants, so far as
they are now obtainable, appears to indicate the deposition of the low-
est coals in the state. at a time subsequent to the formation of the
lower coals of the Lower Coal Measures of the eastern regions, includ-
ing the Morris coal of Illinois, the Brookville and probably the
Clarion coal of Ohio and Pennsylvania, yet perhaps earlier than the
formation of the Darlington or upper Kittanning coals of the two
states last named.

“The study of the distribution of the Henry county flora in this
field shows its closest relations in coals D and E, locally known as the
‘Marcy’ and the ‘Big’ or Pittston coals. But in view of the fact
that the E coal of the Pittston and Wilkesbarre regions seems to carry
many types of a more modern cast, it is not likely that the Missouri
stage is so high in the series as that coal. In the plants of the D coal,
not only are a large part of the species identical with those from Mis-

souri, but the flora as a whole is of a similar type. Compared, how-

ever, with the somewhat equivocal combined flora reported from the
C coal, the material from the Mississippi valley appears on the whole
fully as recent, while lacking many of the older types found at several

REVIEWS 285

of the mines correlated by stratigraphy with that coal. Hence I am
inclined to regard the plants from Henry county, Missouri, as more
clearly contemporaneous with those in the roof of the D or ‘ Marcy’
coal in the northern anthracite field, though they are possibly as old
as the C coal.”

The reference to the unconformity at the base of the Missouri Coal
Measures is full of significance. “‘The transgression of the water level
during the early Mesocarboniferous time has already been discussed
by Broadhead, Winslow, and Keyes, the state geologists. The evidence
of the fossil plants not only corroborates their views in general, but it
also fixes the time of the encroachment of the sea on the old coast in
the region of Clinton. The paleobotanic criteria indicates that the
minimum time represented by the unconformity between Jordan or
Owen coal and the subjacent Eocarboniferous terrane is measured by
the period required for the deposition of the Pottsville and the Clarion
group of the Lower Productive Coal Measures, a series of rocks reach-
ing a thickness of over 1200 feet in portions of the anthracite regions,
and exceeding 2400 feet in southern West Virginia.”

The depositional equivalent of the unconformity at the base of the
Missouri Coal Measures is even more important than Mr. White has
indicated. As quite recently stated there is farther south in Arkansas,
a sequence of Coal Measures beneath the basal horizon of the Des
Moines and Missourian series combined. In reality the geological
position of the Lower Coal Measures (Des Moines series) of Missouri
appears to be well up in the median part of the Middle Carboniferous
instead of at the base, as generally considered. Only in Missouri,
about one half of the Middle Carboniferous is unrepresented by strata.
This lacking series may be represented in Arkansas by upwards of
12,000 feet of sediments!

Attention is called in the monograph to some of the obstacles to
accuracy in correlation and especially to the lack of standard paleo-
botanic sections. If ever there were opportunity of establishing a
standard section of this kind it is in the Trans-Mississippian coal field.
Plant remains occurs abundantly in many localities and at many hori-
zons extending from the very base of Des Moines, up through the
Missourian, into the so-called Permian. The monograph on the
Missouri fossil floras considers chiefly one locality and one horizon.
In Missouri alone there are no less than 150 known localities and 30
horizons for coal plants. In Iowa there are nearly as many more.

286 REVIEWS

Kansas likewise offers an equally inviting field. If a single location
yields up such prodigious possibilities as Mr. White has demonstrated
what may we not expect from the rest of the vast field!

(Co 1k. Ikons,

The Devonian ‘ Lamprey,’ Palaeospondylus Gunni, Traquair. By
BaSHFORD Dean (Mem. N. Y. Acad. Sci., Vol. II, Part I),
13899.

This elaborate memoir of thirty quarto pages and a plate drawn
and lithographed by the author himself represent a vast amount of
labor expended on minute, poorly preserved, and what would seem at
first sight insignificant objects, found in the Caithness flags of Scotland.
The fossil remains of Palacospondylus are very unsatisfactory for study,
and but for the peculiar interest attaching to them as supposed repre-
sentatives of Palaeozoic Lampreys, they would hardly command atten-
tion. But zodlogists have been eagerly awaiting whatever enlightenment
palaeontology might offer on the relations and descent of the Cyclo-
stomes, and when Dr. R. H. Traquair announced his discovery of
Palaeospondylus in 1890, it was hailed with delight as a definite clew to
Cyclostome genealogy.

Dr. Dean observes: ‘‘ Zodlogists were by no means unwilling to
accept Palacospondylus as a fossil lamprey; and they even found it a
difficult matter to avoid going out in the road to give it a charitable
reception. The fossil came, was seen, and was currently accepted.
But time has gone by and suspicion come, and the thought is by no
means comforting that the wrong prodigal may have been welcomed.
Is Palaeospondylus, then, a veritable Cyclostome, or is it at least a pro-
visional one?”’ Dr. Dean’s purpose in investigating this question is a
critical one, and he states that he has “‘attempted to analyze the results
of preceding writers, to contribute some further data to our knowledge
of the structure of this form, and to endeavor finally to determine what
conclusions are justified in assigning a place to this fossil. After
accomplishing all this in very satisfactory fashion, the author takes up
the classification of fishlike vertebrates in general and introduces some
novel changes, which will be referred to presently.

Dr. Dean’s conclusion as to the Marsipobranch nature of Pa/aeo-
spondylus takes the form of a more emphatic denial than ever (see his
previous paper in Proc. Zool. Soc., April 1898) that it can be regarded

REVIEWS 287

even provisionally as a fossil lamprey. Dr. Traquair’s objection that if
Palaeospondylus be not a Marsipobranch it is impossible to refer it to
any other existing group of vertebrates, Dr. Dean disposes of by boldly
placing it in a new class by itself, elevating the order Cycliae, which
Gill created for it, to that rank. Such a course may strike one as rather
startling, perhaps, but it is certainly effective. An alternative propo-
sition which Dr. Dean suggests may be more acceptable to some ich-
thyologists “is to place it with Coccosteus as doubtfully its larval form.”
Although there is considerable reason for regarding the variations in
this small form as the early stages of some larger chordate, yet there
is no direct proof that the adult form was an Arthrodire ; hence this
association would have to be at best only provisional, and, in the author’s
opinion, is inexpedient. As to the relations of newly exalted Cycliae
to other classes, we are left as much in the dark as ever. Some very
excellent figures of the fossil forms are given, together with a diagram-
matic restoration.

Very interesting, indeed, are the author’s views on the systematic
arrangement of the early forms of fishlike vertebrates and fishes proper,
with which the paper concludes. Amongst the latter the Chimaeroids
are reduced again to the rank of an order instead of a subclass, princi-
pally as the result of Dr. Dean’s recent embryological investigations,
and the Dipnoi are reduced from class rank (Parker) to that of a sub-
class. Acanthodes and Cladoselache are grouped together under the
primitive Elasmobranch order Pleuropterygii.

Turning now to the most primitive of all chordates, Dr. Dean ele-
vates the Ostracoderms and Arthrodires each to the rank of an inde-
pendent class, the former with its customary triple subdivision, but the
latter separated into two new divisions, Arthrodira proper and Anar-
throdira, which rank as subclasses. On the yround of their lacking a
mandibular arch and paired limbs, the Ostracoderms were denied by
Cope, and following him by Smith Woodward, and others, to be fishes
at all, but organisms far removed from the latter, called ‘‘ Agnatha.”
The origin and relations of the Ostracoderms are at present among the
most important and fascinating questions of palaeichthyology. Dr.
Traquair, in an extremely valuable memoir of last December" refuses
to believe that these forms are Agnatha, declaring Cope’s view to rest
entirely on negative evidence, and preferring to look upon the lowest

«Report on Silurian Fishes (Trans. Roy. Soc., Edinburgh, Vol. YORNOIDS, IPE IO),
1899.

288 REVIEWS

Ostracoderms “as having definitely split off from the Elasmobranchs,
from which they doubtless originally came.”” Dean believes in a wider
separation, however, from the groups represented by recent forms ; but
regarding the differences between Ostracoderms and Arthrodires, he
makes the following significant remark: ‘“‘A renewed examination of
the subject has caused me to incline strongly to the belief that Pterich-
thys and Coccosteans are not as widely separated in phylogeny as Smith
Woodward, for example, has maintained. But as far as present evi-
dence goes, they appear to me certainly as distinct as fishes are from
amphibia, or as reptiles are from birds or from mammals” (p. 24). The
reference to Smith Woodward bears, of course, on the recognition of
Arthrodires by that author as an order of Dipnoi.

Whatever may be thought of the class Cycliae, there is no question
but that Dr. Dean has scored an advance by elevating the Ostraco-
derms and Arthrodires to a higher rank and placing them in close
proximity to one another. A separation of the two classes is rendered
necessary of course, thus prohibiting the revival of McCoy’s “ Placo-
dermata,” by the absence of ‘‘jaws,”’ endoskeletal structures, and paired
limbs in the first-named group. Nevertheless the two classes have a
number of points in common, and should we be led to infer with Tra-
quair an Elasmobranch derivation of the Ostracoderms, it would be
natural to trace Arthrodires to the same source. Whether there were
really “‘Agnatha,” and how far the archaic fishlike vertebrates were
removed from the groups represented by living forms, must be left for
future study to decide. Or possibly we may never have the solution of
these perplexing problems.

In one minor point only the reviewer finds himself in disagreement
with Dr. Dean, and this relates to the subdivision of Arthrodires (or
“Arthrognaths,” to use his new term) into Arthrodira proper and
Anarthrodira. The latter includes Wacropetalichthys, Trachosteus, Mylos-
Zoma, and certain transitional forms which the author promises shortly
to describe. When the cranial and body armoring of Z7rachosteus and
Mylostoma are made known, their position may become evident. At
present we are acquainted only with the cranial osteology of Macropet-
alichthys,and this is so far different from that of typical Arthrodires
that in the reviewer’s opinion it cannot be retained in the same class.
As typical of an independent family, it had best be removed with the
Asterosteidae to a position amongst the Ostracoderms, as we certainly do
not wish to make of it an independent class. The comparisons between

REVIEWS 289

this form and the cranial and dorsal shields of Arthrodires indicated
by Cope and the’ reviewer a few years ago were based upon a miscon-
ception of the septum dividing off the so-called ‘nuchal plate;” but
in reality no homology exists between arrangement of cranial plates or
the sensory canal system of this form and those of Arthrodires. No
plates corresponding to the dorsal or ventral armoring of Coccosteus, etc.,
are known, nor is there any evidence of a lower jaw, of paired fins, neural
or haemal arches, nor any form of dental plates attached to the roof of
the mouth. Finally, the bone-structure is perceptibly different from
that of typical Arthrodires, and the under side of the head is unparal-
leled in the latter group. This form is certainly worthy of careful
reinvestigation.

The whole matter of Dr. Dean’s Anarthrodira, is, however, of sub-
ordinate importance as compared with his main theme, which is
admirably treated ; and palaeontologists will be sure to appreciate his
clear exposition of the same, supplemented as it is by a complete bibli-
ography and expertly drawn figures.

C. R. EASTMAN.

Some High Levels in the Postglacial Development of the Finger Lakes
of New York. By Tuomas L. Watson. With 30 figures
and 3 maps. The figures being mostly full page half-tones,
maps, and diagrams. Appendix B. Report of the Director
of the New York State Museum, 1899.

Dr. Watson presents in a very clear and interesting manner the
results of the earlier works of other investigators and of his own
extended observations on the high level terraces and water marks in
the Finger Lakes region. He finds that at the time of maximum
advance of the “‘ice of the second glacial period” (by which he prob-
ably means the early or late Wisconsin of some writers) the ice front
extended to and beyond the present divide which separates the waters
draining northward into the St. Lawrence and those of the Chemung-
Susquehanna draining to the southward. The preglacial valleys now
occupied by the Finger Lakes were entirely overridden by the ice but
were not completely filled with the glacial débris, so that as the ice
front began to retreat and had drawn back to a position north of the
divide there was formed, in the valleys, numerous local glacial lakes
which drained southward through several channel ways. These channel

290 REVIEWS

ways were at different levels for the different lakes and as the ice front
drew back to the northeast, the several local lakes coalesced into fewer
larger bodies of water and the higher outlets were abandoned in suc-
cession until finally there was but one body of water, Lake Newberry,
with a single outlet to the southward. This outlet was finally
abandoned when the waters of Lake Newberry fell to the level of and
coalesced with those of Lake Warren. At last the opening of the St.
Lawrence and the lowering of the Lake Iroquois left the waters of the
present Finger Lakes in the old valleys, held back by drift barriers.
The evidence for this sequence of events, which the author traces with
much detail, is found largely in the high level delta deposits made by
the tributary streams in the temporary glacial lakes at the levels of the
southern outlets which mark the successive stages of water levels. Dr.
Watson’s map of the temporary, local, glacial lakes of the Finger Lakes
region suggests that under similar relations of ice front to topographic
form, such as undoubtedly prevailed farther westward in New York and
through northern Ohio, the results of glacial action would be much
the same and that if we are to arrive at a correct interpretation of the
sequence of events during the Pleistocene it will be through the detailed
study of many limited areas in the careful painstaking manner shown
by the work of Dr. Watson. Such work cannot be too highly com-
mended. WaorGe I,

Twentieth Annual Report of the U.S. Geological Survey, Mineral
Resources of the United States, 1898. Washington, D. C.
616 and 804 pages.

The annual report on the mineral resources for 1898 like its pre-
decessors contains much valuable statistical and descriptive matter on
the different mineral products of the United States. The data in the
present report have been brought up to the close of 1898 and, as has been
customary since 1894, when this publication was first made a part of
the annual report, along with the statistical matter there is included
valuable information on the industrial uses, improvements on ore
reduction, new developments, distribution. of ores, chemical analyses,
and other data concerning the different products. The statistics on
some of the products are given in great detail, thus nearly one hundred
pages are devoted to a discussion of the iron ores and the American
and foreign iron trade, which is not an undue proportion of space

ea

REVIEWS 291

when we consider that the value of iron for 1898 was 116.5 millions of
dollars against 227 millions for all the other metallic products. Like-
wise 314 pages are given to the coal and coke industries but the value
of the coal alone is. 208 million dollars against 145 millions for all
other non-metallic products. The total value of all the mineral prod-
ducts for 1898 is $697,820,720 which is an increase over the preceding
year of $66,966,791 or 10.62 per cent.

Some of the more important special topics discussed are (1) the
history of gold mining and metallurgy in the southern states by H. B.
C. Nitze; (2) the characteristics, uses and domestic and foreign pro-
duction of manganese ores by John Birkinbine; (3) the slate belt of
Eastern New York and Western Vermont by T. Nelson Dale; (4)
more than roo pages of analyses and tests of building stones collected
from various sources by Wm. C. Day and classified and arranged by
states; (5) a brief reconnaissance of the Tennesse phosphate fields by
C. Willard Hayes; (6) the mica deposits in the United States by J. A.
Holmes; and (7) the mineral resources of Porto Rico by Robert T.
Hulls and’ A. B.C. Nitze:
Wo (Cs Isl.

Les Charbons Britanniques et Leur Epuisement. By Ep. Loz.
Two volumes. Paris, 1900.

This work is an exhaustive treatise on British coals, comprising a dis-
cussion of their history, exploitation, production, consumption, geologi-
cal occurrence, value, qualities, classification, utilities, and exportation.
The work as whole is divided into four parts. Part one presents a
general discussion of the geography and inhabitants of Great Britain
and Ireland; their social, political, and economic conditions; the
influence of the coal industry on economics, navigation, naval power,
and the national debt; the geology of the British Isles ; the history of
coal production and the statistics bearing on its production and con-
sumption. ;

Part two furnishes a description of the coal beds of the United
Kingdom and discusses their importance and productiveness. This
is followed by a series of chapters on the industrial and commercial
geography of the Islands, constituting the third part of the work.
The fourth part treats of the productiveness of the coal mines, and the
probable time of depletion.

292 REVIEWS

It is thought probable that coal was first used in Britain by the
early Bretons, but direct evidence of it is wanting. However, it is
known to have been used by the Roman invaders, as cinders and coal
ashes have been found in the ruins of the Roman houses. Not
much is known of the coal industry from the time of the Roman inva-
sion until the beginning of the thirteenth century when it is referred
to in certain land grants. ‘The first mines were located in the vicinity
of Newcastle. By the year 1379 coal had become of sufficient impor-
tance to make it an object of impost. By the beginning of the six-
teenth century the production had reached an average of a million
tons per year, and the total production from that date to 1866 is esti-
mated to be 850 million tons. .

The principal coal beds of the United Kingdom occur in the Coal
Measures or upper part of the Carboniferous series. According to
Hull the Lower Carboniferous has a threefold division: (1) the lower
schist group, (2) the Mountain limestone, and (3) the Yoredale group.
The Upper Carboniferous is divided into (1) the Millstone grit, (2) the
lower Coal Measures, (3) the middle Coal Measures, and (4) the upper
Coal Measures. The last three divisions contain the productive coal
beds. The work is accompanied by maps locating accurately the
known coal areas and giving the probable extent of the undetermined
ones.

The coals of Britain are classed under the heads of:

1. Lignites, containing 67 per cent. of carbon and 26 per cent. of
oxygen.

2. Bituminous coal, containing 75 to go per cent. of carbon and 6 to
Ig per cent. of oxygen.

3. Steam coal, a sort of semi-anthracite.

4. Cannel coal, containing 4o per cent. of volatile matter and being
rich in hydrogen.

5. Anthracite coal, containing 93 to 95 per cent. of carbon and 3 per
cent. of oxygen with 2 to 4 per cent. of hydrogen.

The total exportation of coal from the British Isles in 1898 was 35
million tons, which was a decrease over the preceding year of about
300,000 tons. The importation of coal for 1897 was only 9454 tons.
The amount of coal consumed per capita in 1898 was 3.867 tons.

The author discusses the estimate made by the Commission of
1870, that the coal resources of the United Kingdom are 80 billion
tons, and that at the present rate of depletion (2 million tons per year)

REVIEWS 293
the total exhaustion will take place in four hundred years ; and arrives
at the conclusion that the time may be even less than that given by
the Commission. That the day of complete depletion will come, the
author is assured, and when it does come ‘the historian of a powerful
empire will terminate, very probably, the narrative of a remarkable
epoch with these words, fnzs Britannae.” W. N. Locayn.

Cape Nome Gold Region. By FRANK C. SCHRADER and ALFRED
H. Brooxs. United States Geological Survey, Special
Report, 56 pp. Washington, 1900.

The Cape Nome gold field which has recently occasioned so much
excitement is of special interest geologically on account of being the
most noteworthy modern beach placers known. The type of ore
deposits to which these Alaskan beds belong has long been recognized,
but no bodies of this kind have ever proved so rich. Ancient deposits
of the same origin are not unknown. Such are the Witwatersrand
blanket of the Transvaal and the Napoleon Creek conglomeratein Alaska.

The Nome district is on the southern shore of the Seward peninsula
in a little known part of northwestern Alaska. ‘The beach rises gradu-
ally to a sharply cut bench, a hundred to two hundred yards from the
surf. From the edge of this terrace, which is about twenty feet high,
the moss-covered tundra extends inland, rising uniformly about two
hundred feet in four or five miles, when it merges into the highland belt.”

The bed-rock of the region is composed of limestones and phyllites
or mica schists interbedded, with some gneiss. Igneous rock is of rare
occurrence. Over this foundation lie the unconsolidated gravels with
gold-bearing zones. The authors emphasize the fact that during the
deposition of the gravels and sands the conditions were not materially
different from those of today, except that the land stood at a lower
elevation relatively to the sea. ‘There is no evidence whatever of
glacial action in the region, and the popular idea that the gravels were
brought to their present position by ice action is entirely erroneous.”

The gold-bearing deposits are grouped into gulch-placers, bar-
placers, beach-placers, tundra-placers, and bench-placers. The gulch
and beach placers are the most productive. During the past year
(1899) the production was three million dollars.

The gold is usually rounded and often smoothly polished. It is
not evenly distributed through the gravels but gathered in zones. In

204 REVIEWS

washing the pay-streaks the heavy minerals garnet and magnetite are
concentrated along with the gold. ‘The first forms ‘‘ruby sand” and
the latter “black sand.”’

Good prospects for gold occur in many other places in the Seaward
peninsula. ‘The geographic portions of some of the different local-
ities suggest that they may belong to the same gold belt. The facts
known to us, however, are not sufficient to prove this; and it must
simply be regarded as a working hypothesis. Should subsequent
development and investigation show that the gold of all of these districts
of Seward peninsula is derived from the same series of rocks, this gold-
mining region will embrace an area of at least 5000 to 6000 square
miles. If this proves to be the case, it does not by any means follow
that the entire belt will contain workable gold deposits. We should
rather expect to find the gold confined to certain zones within the belt.”

The report is accompanied by a number of excellent views of the
region. This preliminary report gives us a good idea of just what the
visitors and prospectors may expect when they reach the Cape Nome
region. Scientists will await the appearance of the final report with
interest. Ca Rev keewns:

Syllabus of Economic Geology. By JouN C. BRANNER, Ph.D., and
Joun F. Newsom, A.M., Second Edition, 1900, pp. 368.
Plates and Diagrams.

This volume is a syllabus of a course of lectures on economic
geology given by the authors at Leland Stanford Junior University.
It is intended primarily for the student, but will also be found a most
valuable guide to anyone interested in the various branches of economic
geology. It begins with a general list of the more important works on
economic geology, and of the periodicals relating to this subject. After
this are a few introductory remarks on geology in its relation to various
economic subjects, including mining, agriculture, forestry, manufac-
turing, industries, art, roads, railways, migration, etc., followed by a
brief synopsis of geological sections, maps, surveys, etc., from an
economic standpoint; a summary of economic geological products and
their various classifications as proposed by different authors; rock-
cavities ; the formation of ore bodies; and the features of ore deposits.
This general part of the subject takes up the first fifty pages, and most
of the rest of the volume treats of different kinds of ore deposits and

REVIEWS 295

other deposits of economic value, including iron, chromium, manganese,
copper, tin, cobalt and nickel, zinc, lead, silver, gold, platinum group,
tungsten, molybdenum, antimony, bismuth, cadmium, arsenic, mer-
cury, precious stones, coal, graphite, petroleum, natural gas, ozokerite,
asphalt, salt, soda, borax, niter, soda niter, barytes, sulphur, iron pyrites,
feldspar, fluorite, mineral pigments, abrasives, marble, limestones other
than marble, building stones in general, kaolin, clay, bauxite, aluminum,
glass sand, refractory materials, natural fertilizers, monazite, road
materials, soils and water. Under each of these headings is given a
brief account of the chemical and mineralogical character of the
material under discussion, its mode of occurrence, its distribution, and
other technical or commercial data of interest, together with a list of
the more important literature on the subject. The volume closes with
a few very pertinent remarks and suggestions on the subject of reports
on mining properties, and with a list of references to works on mining
law.

The lists of literature given in the volume contain the more impor-
tant publications on the different subjects treated, and though, as the
authors themselves say, they have not attempted to make the bibliog-
raphy complete, yet the references which they have given are all
useful and will be found to be a ready guide to those who wish to
follow up the subject further. For the student, this system is espe-
cially useful, as he gets in the syllabus only references to thé most
important literature, and is not encumbered with what is not immedi-
ately necessary for his purposes; at the same time he has the means of
finding any other literature that may exist on the subject. A very
useful feature of the volume are the blank pages which alternate with the
pages of printed matter, thus giving means of inserting further refer-
ences to literature or making short notes, etc.

The volume contains 141 illustrations including geological sections,
sections of ore bodies and of mines, statistical tables, etc., all of which
add greatly to the usefulness of the work as they make it possible in a
condensed form to understand clearly the various subjects discussed.

The volume relates mostly to the economic geology of the United
States, but that of foreign countries is occasionally mentioned. It
covers a wide field in a form which though condensed is sufficiently
full to answer all the purposes for which it is intended. It is a most
valuable work, and the thanks of all interested in economic geology
are due to the authors who have prepared it. OUR ovale! 18S dees Tis,

RECENT FUBLICATIONS

—American Museum of Natural History, Bulletin of. Vol. XII, 1899. New
York, February 1goo.

—Atti della Accademia Olimpica Di Vicenza, Primo e Secondo Semestre,
1896, Vol. XXX.

/otd., Annate, 1897-8, Vol. XXXI.

—BAIN, H. Foster. The Geology of the Wichita Mountains. Bull. Geol.
Soc. of America, Vol. II, pp. 127-144, Pls. 15-17. Rochester, March
1g0o.

—Bascom, Dr. F. Volcanics of Neponset Valley, Massachusetts. Bull.
Geol. Soc. Am., Vol. II, pp. 115-126. Rochester, March 1goo.

On Some Dikes in the Vicinity of Johns Bay, Maine. Am. Geologist
Vol. XXIII, May 1899.

—BEECHER, C. E. Conrad’s Types of Syrian Fossils. From the Am. Jour.
Sci., Vol. IX, March 1goo.

On a Large Slab of Uintacrinus from Kansas. Am. Jour. Sci., Vol. IX,
April 1900.

—BERTRAND, M. MARCEL. Les Grands Charriages et Le Déplacement du
Pole. Institut de France Academie des Sciences.

La Mappe de recouvrement des environs de Marseille. Lame de
Charriage et rapprochement Avec le Bassin houiller de Silésie. Extrait
du Bull. la Soc. Genl. de France, 1898.

I. Etude Géologique sur L’Isthme de Panama. II. Les Phenoménés
Volcaniques et les Tremblements de Terre de L’Amerique Centrale.
—BROGGER, W.C. Om de senglaciale og postglaciale nivaforandringer i
Kristianiafeltet. Norges Geologiske Under sélgelse No. 31a. Kristiania,

1900.

_—BrYANT, HENRY G. Drift Caska to Determine Arctic Currents. (Read
at the VII International Geographical Congress of Berlin 1899.)

—COLEMAN, ARTHUR P. Upper and Lower Huronian in Ontario. Bull.
Geol. Soc. of Am., Vol. II, pp. 107-114. Rochester, March Igoo.

—Davis, W.M. Glacial Erosion in the Valley of the Ticino. Extract
from Appalachia, IX, 2, March 1goo.

Balze per Faglia nei Monti Lepini. Traduzione de! Socio Fr. M. Passa-
nia. Societa Geografica Italiana. Roma, 1899.
Fault Scarp in the Lepini Mountains, Italy. Bull. Geol. Soc. Am.,
Vol. II, pp. 207-216, Pls. 18-19. Rochester, April Igoo.
296

RECENT PUBLICATIONS 207

—DEWALQUE, G. Mélanges Geologiques. Académie Royale de Belgique.
(Extrait des Bulletins, 2™° série, tome XXII, 1890-1897). Bruxelles et
Liége.

—DILt_ER, J.S. The Bohemia Mining Region of Western Oregon with
Notes on the Blue River Mining Region and on the Structure and Age
of the Cascade Range. Accompanied by a Report on the Fossil Plants
associated with the Lavas of the Cascade Range. By F.H. Knowlton.
Extract from the 20th Annual Report of the U. S. Geol. Survey, 1898-9.
Washington, Igoo.

—FAIRCHILD, HERMAN L. Glacial Geology in America. An Address
before Section of Geology and Geography of the American Association
for Advancement of Science, Boston Meeting, August 1898. Salem
Press Co., Salem, Mass.

—FARRINGTON, OLIVER C., PH.D. I. New Mineral Occurrences. II.
Crystal Forms of Calcite from Joplin, Missouri. Field Columbian
Museum Publication 44 Geological Series, Vol. I, No. 7, Chicago,
February 1900. ’

—Geological Society of America, Proceedings of the Eleventh Summer Meet-
ing held at Columbus, Ohio, August 22, 1899. Vol. XI, pp. I-14.
—Geological Survey of Canada, Summary of the Mineral Production of

Canada for 1899. Ottawa, February 1goo.

—GERHARDT, PAuL. Handbuch des Deutschen Diinenbaues Verlagsbuch-
handlung. Paul Parey in Berlin.

—GRANT, ULYSSES SHERMAN, PH.D. Preliminary Report on the Copper-
Bearing Rocks of Douglas County, Wis. Bulletin, No. VI, Economic
Series, No. 3, Geological and Natural History Survey, Madison, Wis.,
1goo.

—HAatTcHER, J. B. Sedimentary Rocks of Southern Patagonia. Am. Jour.
Sci., Vol. 1X, February 1goo.

—Hitrcucock. H. Geology of Oahu with Notes on the Tertiary Geology of
Oahu by W. H. Dall. Bulletin Geological Society of America, Vol.
XI, pp. 15-60, Pls. 1-8. Rochester, Igoo.

—HO.uuick, ARTHUR. Some Features of the Drift on Staten Island, N. Y.
Contributions from the Geological Department of Columbia University.
[Annals of the N. Y. Acad. Sci., Vol. XII, No. 4, pp. 91-102, Pl. 1.]

—Kemp, JAMES F. The Ore Deposits of the United States and Canada.
Third Edition. Entirely re-written and enlarged. New York and Wash-
ington. The Scientific Publishing Co., I1goo.

—KO6rto, B. Pu.D. Notes on the Geology of the Dependent Isles of Taiwan.
Reprinted from Journal College of Science. Imperial University, Tokyo,
Japan, Vol. XIII, Part 1, 1899.

298 RECENT PUBLICATIONS

—LeE ConreE, JOSEPH. A Century of Geology, Reprinted from Appleton’s
Popular Science Monthly for February and March 1goo.

—LozE, Ep.. Les Charbons Britanniques et Leur Epuisement. Tome
Premier and Deuxieme. Paris, 1goo.

—MarTEL, E. A. La Spéléologie ou Science des Cavernes. Scientia,
Mars, 1900. Biologie, No. 8. Georges Carré and C. Naud, Editeurs.
Paris, 1900.

—McGeEE, W J_ Cardinal Principles of Science. Proc. Washington Acad-
emy of Sciences, Vol. II, pp. 1-12, March rgoo.

—MERRIAM, C. Hart. Papers from the Harriman Alaska Expedition I,
and Descriptions of Twenty-six New Mammals from Alaska and British
North America. Proc. Washington Academy of the Sciences, Vol. II,
pp. 13-30, March tg00. Washington, D. C.

—MILLER, GERRIT S., Jk. The Bats of the Genus Monophyllus. A New
Shrew from Eastern Turkestan. Proceedings Washington Academy of
of Sciences, Vol. II, pp. 31-40, March 30, 1902.

—Noves, Wa. A., W. F. HILLEBRAND and C. B. DUDLEY. Report on
Coal Analysis. Reprinted from the Journal of the American Chemical
Society, December 1899.

—OLpDHAM, R. D. III. On the Propagation of Earthquake Motion to great
Distances, Phil. Transactions of the Royal Society of London. Series
A, Vol. 194, pp. 135-174. London, Igoo.

—ORDONEZ, M. EZEQUIEL, M.S.A. Note sur les Gisements D. Or Du
Mexique. Edicion de la Sociedad ‘‘ Antonio Alzate.” Mexico, 1898.

—PROSSER, CHARLES S. Gas-Well Sections in the Upper Mohawk Valley
and Central New York. From the American Geologist, Vol. XXV,
March 1goo.

—Rtres, HEtnricH. The Origin, Properties and Uses of Shale. Michigan
Miner, November 1, 1899.

—ROGERS, A. W. and E. H. L. SCHWARTz. Notes on the Recent Lime-
stones on Parts of the South and West Coasts of Cape Colony. Trans-
actions of the South African Philosophical Society.

—RoTHPLETZ, A. Ueber die eigenthiimliche Deformationen jurassischer
Ammoniten durch Drucksuturen und deren Beziehungen zu den Stylo-
lothen. Miinchen, 1goo.

Die Entstehung der Alpen. Sonder-Abdruck aus ‘‘ Bayer. Industrie u.
Gewerbeblatt.”’

—SALISBURY, ROLLIN D., and WALLACE, W. ATwoop. The Geography of
the Region about Devil’s Lake and the Dalles of the Wisconsin. With
Some Notes on Its: Surface Geology. Bulletin No. V, Educational

RE CENIMPOBELGCA TIONS. 299

Series, No. 1, Wisconsin Geological and Natural History Survey, Madi-
son, Wis.

—SEE, T. J. J. Onthe Temperature of the Sun and the Relative Ages of
the Stars and Nebulae. Transactions of the Academy of Science of St.
Louis, Vol. X, No. 1, February Igoo.

—SCHRADER, FRANK C., and ALFRED H. Brooks. Preliminary Report on
the Cape Nome Gold Region, Department of Interior U. S. Geological
Survey, Washington, D. C., Igoo.

—SCHUCHERT, CHARLES. On the Lower Silurian (Trenton) Fauna of Baffin
Land. From Proceedings of U. S. National Museum, Vol. XXII, pp.
143-147. Washington, Igoo.

Lower Devonic Aspect of the Lower Helderberg and Oriskany Forma-
tions. Bull. Geol. Soc. Am., Vol. lI, pp. 241-332. Rochester, goo.

—SMITH, GEORGE OTIS, and CARROLL CuRTIS. Camasland: A Valley

Remnant.

—SMITH, GEORGE OTIS, and WALTER C. MENDENHALL. Tertiary Granite
in the Northern Cascades. Bull. Geol. Soc. Am., Vol. II, pp. 217-230,
Pl. 20. Rochester, Igoo. :

—SpurR, J. E. Classification of Igneous Rocks according to Composition.
American Geologist, Vol. XXV, April Igoo.

—Topp, JAMES E. Vermillion, South Dakota. New Light on the Drift in
South Dakota. From the American Geologist, Vol. XXV, February
Tgoo. ‘

—TuRNER, H. W. The Esmeralda Formation. From the American Geol-
ogist, Vol. XXV, March Igoo.

—United States Geological Survey, Monograph of. Vol. XX1X, Department
of the Interior, Document No. 581. Washington, D. C.

—WALCOTT, CHARLES D. Random, a Pre-Cambrian Upper Algonkian Ter-
rane. From Bulletin of Geological Society of America, Vol. II, 1899.
Cambrian Fossils of the Yellowstone National Park. Extract from
“Geology of the Yellowstone National Park,’ Monograph XXXII of the
U.S. Geological Survey, Part II, Chap. XII, Section I. Washington,
1899.
—WakRD, LESTER F. Report on the Petrified Forests of Arizona. Depart-
ment of the Interior. Washington, Igoo.

—WaARD-CONLEY Collection of Meteorites. Catalogue. Henry A. Ward, 620
Division St., Chicago, Il.

—Washington Academy of Sciences, Proceedings of, Vol. I, 1899. Washing-
(ioim,, 1D), (C-

300 RECENT, PUBLICATIONS

—Wartson, THomAS L. Some High Levels in the Postglacial Development
of the Niagara Lakes of New York State. A Thesis presented to the
Faculty of Cornell University for the Degree of Doctor of Philosophy,
March 1808.

—WEBSTER, CLEMENT L. A Monograph on the Geology and Paleontology
of the Iowa Devonian Rocks. Charles City, Iowa, Igoo.

—WEED, WALTER HARVEY. Enrichment of Mineral Veins by Later Metallic
Sulphides. Bull. Geol. Soc. of Am., Vol. II, pp. 179-206. Rochester,
1900.

—WELLER, STUART. Kinderhook Faunal Studies, Il. The Fauna of the
Chonopectus Sandstones at Burlington, Iowa. Reprinted from the
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February 1goo. :

—WHITE, Davip. Relative Ages of the Kanawhaand Allegheny Series as
Indicated by the Fossil Plants. Bull. G. S. A., Vol. II, pp. 145-178.
Rochester, March !goo.

—WINCHELL, N. H. The Geological and Natural History Survey of Minne-
sota. The Twenty-fourth (and final) Annual Report for the Years 1895—
1898. Minneapolis, 1899.

—WoopmMaN, J. F. Shore Development in the Bras D’Or Lakes. American
Geologist, Vol. XXIV, December 1899.

Studies in the Gold-Bearing Slates of Nova Scotia; Proceedings of the
Boston Society of Natural History, March 1899.

Ore-Bearing Schists of Middle and Northern Cape Breton; Report of
Department of Mines, Nova Scotia, year ending September 1808.
—WoosTER, L. C., PH.D. The Geological Story of Kansas. Twentieth
Century Classics. Vol. II, No.1, March 1900. Crane & Co., Topeka,

Kas.

—WriecutT, A. A. The Topographic Survey of Ohio. Its Nature, Utility
and Cost.

—ZEILLER, R. Eléments de Paleobotanique. Georges Carré and C. Naud,
Editeurs 3, Rue Racine, 3, Paris, 1900.

(OUI Me Or GEOLOGY

MAY—FUNE, 1900

METHODS OF STUDYING EARTHQUAKES

I PROPOSE in this paper to consider the methods of studying
earthquakes of a moderate degree of intensity, z. ¢., those which
disturb areas of not more than a few thousands of square miles,
and which as a rule are too weak to cause any very serious
damage to property. Of such earthquakes, about ten or twelve
are felt every year in Great Britian; the majority are slight, but
once in four or five years a shock will occur that is noticed over
a district containing more than 50,000 square miles. The
methods of investigation do not, however, vary much in these
cases; but, as they can only be applied with success in rather
populous countries, it seems possible that they may be as useful
in certain parts of the United States as they have already proved
to be in the British Isles.
~The whole aim of an earthquake inquiry has been widened
during the last ten years. It is no longer merely a question of
determining the position of the epicenter, though this is still one
of the first problems to be solved. We have to ascertain not
only the place where a fault-slip occurred, but the direction of
the originating fault, its hade, and the nature of the movement
which gave rise to the shock; for the earthquake is but a pass-
ing incident in the growth of a fault. It is the transitory effect
on the surface.of a displacement, within the earth’s crust; and
Vol. VIII, No. 4. 301

302 CHATLES DAVISON:

the displacement, rather than its effect, is the more important
subject for investigation.

For determining the position of the epicenter, three methods
have been employed, depending respectively on observations of
the direction, time of occurrence, and intensity of the shock.

The first method was suggested by Mallet, and used by him
in studying the Neapolitan earthquake of 1857, and by a few
other seismologists who have followed in his steps., Later on, the
method fell into disrepute; and, so far as it depends on individual
observations of the projection or fall of bodies, etc., it must, I
think, be regarded as unreliable. But, if the number of observa-
tions be large, the average of all the records in one place may
give a close approximation to the true direction. This was first
shown by Professor Omori for the Tokio earthquake of 1894. In
that city, the earthquake, besides a number of minor vibrations,
consisted of a single great oscillation, the maximum displacement
in which wase73 42 inv therdixection Wa Zone S-sand Om Ne
Many columns and monuments were overthrown, and especially
a large number of ‘Ishidoro” or stone lamp-stands placed in
gardens. Professor Omori measured the directions in which 245
bodies fell in different parts of the city, 144 being ‘‘ Ishidoro”
with circular bases. The directions are extremely varied, and at
first sight appear to be subject to no law, but the mean direction
given by all the observations is W. lo}, Se and) 3 woeeNeoeelitnwe
take only the 144 ‘‘Ishidoro” with circular bases, and regard all
the determinations of the direction as of equal value, we find the
mean direction to agree exactly with that given by the seismo-
graphic record, and to have a probable error of less than two
de gneesiaas

The study of the Hereford earthquake of 1896 led to a some-
what similar result. In this case, observations of overturned
bodies were not available, and the estimates of the direction were
all made from personal impressions. They are extremely rough,
few of the observers referring to more than the eight principal
points of the compass. Moreover, as a general rule, the apparent

t Bull. della Soc. Sismol. Ital., Vol. II, 1896, pp. 180-188.

METHODS OF STUDYING EARTHQUAKES 303

direction of the movement was nearly perpendicular to one
of the principal walls of the house in which the estimate was
made. But this very fact, which seems to render the observa-
tions valueless, turns out to be of service; for the impression of
direction is most distinct in buildings whose walls are perpen-
dicular to the true direction of the shock. The majority of the
records naturally come from such houses, and thus the average
of all the estimates collected gives a nearly accurate result. The
mean directions for London and Birmingham, for instance, inter-
sect almost exactly in the epicenter, and those for several
counties pass within a short distance of this spot.* Thus the
method of directions, if we give a somewhat different meaning
to it from that intended by Mallet, may determine the position
of the epicenter with a close approach to accuracy.

It is doubtful whether the second method, depending on
time-observations, can ever lead to any but very rough results.
The chief reason for this is the difficulty of determining the time
accurately to within a few seconds. But, supposing this were
possible, there is also the uncertainty whether it is the same
phase of the motion which is timed by observers in different
places; for the vibrations which appear strongest to different
persons do not necessarily come from the same part of the focus,
and may come from parts which are separated by a distance that
is considerable when compared with the dimensions of the dis-
turbed area. While good time-observations may enable us to
determine the surface velocity of the earth-wave, they can hardly,
unless very numerous, afford information of much value with
regard to the position of the epicenter, and still less with regard
to the depth of the focus.

There remains the third, and by far the most fruitful, method
of inquiry —that which is founded on the intensity of the shock.

“The Hereford Earthquake of 1896” (Cornish Bros., Birmingham,) pp. 265-270.
I have applied this method to the Charleston earthquake of 1886, for which Captain
Dutton’s well-known memoir supplies the materials. Here it was necessary to group
together observations in separate states, the areas of which are to large to give good

results. But, in several cases, the mean direction so obtained differs only by a few
dezrees from the line joining the center of the state to the epicenter.

304 CHARLES DAVISON

By means of an arbitrary scale, for which we are indebted to the
joint labors of Professors M. S. de Rossi and F. A. Forel, the
intensity at any place may be expressed according to the
mechanical effects produced by the earthquake. A series of iso-
seismal lines may then be drawn, each surrounding the places
where the shock was of a given intensity and excluding those
where it was distinctly less; and if the series is complete, the
innermost isoseismal enables us to determine the position of the
epicenter, generally with a close approach to accuracy.

But the method of intensities does more than this. When the
isoseismal lines are carefully drawn—and this is only possible
roughly elliptical in form; their longer. axes are parallel or
nearly so, but they are not coincident. In my report on the
Hereford earthquake (pp. 216-218), it is shown that this must
be the case when the earthquake is due to the friction generated
by a fault-slip; for the focus is then a surface inclined to the
horizon. Moreover, the focus and relative positions of the iso-
seismal lines are indices of the direction and slope of the fault-
plane. The longer axes of the curves are parallel to the fault-line
or strike of the fault; and, on the side toward which the fault
slopes, the isoseismal lines are further apart than on the other
side of the fault-line, except at great distances in the case of a
strong earthquake, when the inequality is reversed.

I can give no better example of a slight earthquake than that
which occurred on April 1, 1898, in the south of Cornwall. The
positions of the principal places where it was felt are shown in
Fig. 1, but the coast-line is omitted in order to simplify the
diagram. The continuous curves represent the isoseismal lines
of intensities 4 and 3 of the Rossi-Forel scale; and their forms
and relative position show that the fault-line must run from
Be 23° Whe wo WW 38° Sy ancl Wmat wine tiault mmst Ince to tle
southeast.

The latter inference is corroborated by the study of the
sound-phenomena, to which the two dotted lines relate. The
outer of these lines represents the boundary of the sound-area,

* Quart. Jour. Geol. Soc., Vol. LX VI, 1900, pp. 1-7.

METHODS OF STUDYING EARTHQUAKES 305

while the inner one separates those places where the sound
was loud from those where it was distinctly fainter. As the
more prominent sound-vibrations appear to come from the upper
margin of the seismic focus’, the northwesterly shift of the
sound-curves with respect to the isoseismal lines implies that the
fault hades in the direction opposite to them.

One of the most interesting features of British earthquakes,
though it is by no means confined to them, is the double nature
of the shock. At
many places there
are two distinct
series of vibrations
separated by a brief
interval of absolute
rest and with a large
number of observa-
tions—they are asa
rule quiet. This was
the case during the
Hereford earth-
quake of 1896 near-

ly all over the dis-

Gor

iUGweG saneay | e-NS) a

rule, however, a weak tremor and a faint rumbling noise are
observed during the interval at places near the epicenter ; while
at considerable distances from the origin these become imper-
ceptible, and the shock appears to consist of two detached por-
tions. The double shock is chiefly characteristic of strong or
severe earthquakes but there are several slight ones in which it
has been observed. Attempts have been made to explain it by
the reflection or refraction of the earth-waves at the bounding
surfaces of strata, or by the existence of longitudinal and trans-
versal vibrations. But the wide distribution of the places where
the double shock is observed and the fact that the relative nature
of the two parts of the shock is not constant all over the

* Phil. Mag., Jan. 1900, pp. 66-70.

306 CHARLES DAVISON

disturbed area, are conclusive against any theory based on the
assumption of a single initial impulse. In the cases which have
been investigated, there can be no doubt, I think, that there were
two distinct foci, and that the impulses at them were nearly, but
not quite, simultaneous. In the Charleston earthquake of 1886,
Captain Dutton was able to locate the two foci; and this has
also been done in several British earthquakes.

There appear, however, to be two distinct classes of earth-
quakes in which a double shock is observed; of which the
Cornish earthquake of 1898 and the Hereford earthquake of
1896 may be regarded as respective types. The chief outward
difference consists in the length of the interval between the two
parts of the shock. In the first case, the interval was a quarter
of a minute or more in length; inthe second, it varied from a
few seconds to zero. The Cornish earthquake consisted in real-
_ ity of two successive earthquakes originating in nearly the same
region of the fault, and the foci were overlapping. The Here-
ford earthquake was a true fwzm earthquake, the foci were com-
pletely detached; but the impulses at the two foci were due
to the same initial stress, and the impulse at the second was
in no way a consequence of that at the first, for it took place
before the earth-wave from the first had time to reach the
other.

The two parts of a twin earthquake differ as a rule in intensity,
in duration, in the period of their vibrations, and possibly in other
ways. The distribution of the places where the first part was
stronger, etc., than the second, enable us to determine at which
focus the initial impulse was the more powerful and which was
first in action. In the Hereford earthquake, the region in which
the first part of the shock was stronger, of greater duration, and
consisted of slower vibrations, was separated from that in which
the same features characterized the second part, by a hyper-
bolic band, passing between the two foci. Within this band the

* The explanation of the double shock givenin the report on the Hereford Earth-

quake (p. 295) I believe to be generally true for twin earthquakes; but I propose to
consider the subject more fully in another paper.

‘

METHODS OF STUDYING EARTHQUAKES 307

two parts of the shock were superposed, showing that the
impulses were not simultaneous, and that the focus within the
concave part of the hyperbola was last inaction. In the Cornish
earthquake of 1898, the interval between the two parts of the
shock was so great that the first and weaker part was felt all
over its disturbed area before the second was felt at its epicenter.
Consequently, the broken line in Fig. 1, which surrounds all the
places where the double shock was observed, constitutes the
boundary of the disturbed area of the earlier portion.

In studying an earthquake, there will be found on almost every
point considerable conflict in the evidence collected. Much of it
is no doubt due to inaccurate observation, part to a misunder-
standing as to the information desired. It is in the records of the
sound phenomena that the greatest diversity exists, a diversity
which can hardly be ascribed to inattention or defective observa-
tion, and which can only be explained completely on the suppo-
sition that the sound is so deep that some persons are incapable
of hearing it. Near the epicenter, the strength of the sound-
vibrations is so great that they are audible to nearly every person,
but the percentage of observers who hear the sound decreases
rapidly towards the boundary of the sound-area. The variation
in audibility throughout the sound-area may be illustrated by
means of isacoustic lines. The percentage of auditors of the
sound among those observers within a given area who felt the
shock is taken to correspond to the center of the area in question,
the lines joining adjacent centers are divided so as to give points
where the perccntage would, on the hypothesis of uniform varia-
tion, have certain definite values, say 90, 80, 70, etc., and lines
are drawn through all points where the percentage marked is the
same. The isacoustic lines for the Hereford earthquake of 1896
are represented in Fig. 2. The axis of the isoseismal lines runs
almost exactly northwest and southeast, and the points of great-
est extension of the isacoustic lines lie on a curve (broken in the
figure) which coincides almost exactly with the hyperbolic
band referred to above. The explanation of the peculiar distor-
tions of the isacoustic lines is that, along this band, the

308 CHARLES DAVISON

sound-vibrations from both foci were heard simultaneously, and
the additional strength thus rendered them audible to an
increased percentage of observers.*

The variation of other phenomena may be similarly repre-
sented —such as the frequency of comparison of the sound to

WIE, BL

definite types, the audibility of the sound-vibrations before and
after the shock is felt, the audibility of the loud crashes heard
when the sound is loudest, etc. The method of course requires
a very large number of records for its employment ; but, in no
other way, can the influence of erroneous or defective observa-
tions be so successfully eliminated.

CHARLES DavISON.
Kinc EDWARDS HIGH SCHOOL.

tPhil. Mag., Jan. 1900, p. 43.

GEACIALE GROOVES AND ysSlRIAE IN SOUTHEAST -
ERN NEBRASKA’

NEBRASKA is so close upon the western as well as the south-
ern limit of the drift that evidences of glacial action which
might be commonplace elsewhere are rare and interesting here.
The mere fact that glacial grooves and striae have been found
seems worthy therefore of mention. Glacial drift, readily rec-
ognizable as such, does not extend far west of the 97th merid-
ian, and in but one place in the state, on the Dakota-Nebraska
boundary, does it reach the g8th meridian. East of the 97th
meridian it is distinct and unmistakable, and it may be offered
as a safe statement that probably in no other state is the glacial
drift so generally recognized as such by the mass of the people.
This is due to the presence of numerous bright red and purple
bowlders of Sioux quartzite. They are unmistakable, and it is
generally known that they have been transported from the
region of Sioux Falls in South Dakota, and scattered along the
eastern border of Nebraska, and south into Kansas. Bowlders of
Sioux quartzite twenty feet in diameter are to be found as far
south as the Nebraska-Kansas line. A heavy mantel of drift,
overlaid by a hundred feet or so of loess, so effectually con-
ceals the rocks that exposures are rare, and striations and simi-
lar evidence of glacial action, which may be common enough in
fact, are not seen. The first were found by the author in 1894
on a slab of Carboniferous limestone in the old Reed quarry one
mile northeast of Weeping Water.

Though not found exactly in place it was unmistakably
native rock. The ledge from which it came has just been found
by Mr. E. G. Woodruff (Univ. Nebr. 1900). It is a narrow
ledge perhaps 300 feet long by five to six feet wide, leveled,
smoothed, and striated throughout. The grooves and striae run
south eleven degrees east. One groove, the most conspicuous

tPaper read before the Nebraska Academy of Science, December 2, 1899.

309

310 ERWIN HINCKLEY BARBOUR

Fic. 1.—Glaciated surface, carboniferous limestone, Weeping Water, Nebraska,
badly shattered by a blast, yet plainly showing striae and grooves. ‘The -central
groove varies from three to four inches in width, and is about one and one quarter
inches deep, and runs south 29° west. From a photograph by the writer.

noted, being three inches across and one and a quarter deep, ran
south twenty-nine degrees west. There were numerous ragged
grooves varying from one quarter to one half inch in depth, and
innumerable closely crowded parallel striae. The whole surface
was reduced to a plane, portions of which were well polished.
Upon it rested a thin layer of drift consisting of a little clay,
numerous large pebbles and an occasional bowlder of Sioux

ee

GEACIAL GROOVES AND STRIAE IN NEBRASKA 311

Fic. 2.—Cabinet specimen (7 by 10 in.) in the State Museum of Nebraska, show-
ing planed surface and glacial striae on carboniferous limestone, Weeping Water,
Nebraska. Striae run south 11° east. Photograph of a specimen procured by the
writer in 1894. :

Fic. 3.—Cabinet specimen (7 by 10 in.) in the State Museum of Nebraska, show”
ing planed and polished surface, striae, and a small glaciai groove, carboniferous
limestone, \Weeping Water, Nebraska. Photograph from a specimen secured by Mr.
E. G. Woodruff, fall of 1899.

312 ERWIN HINCKLEY BARBOUR

quartzite, the largest noted being about three feet through. The
drift is thin here, nowhere exceeding a foot or two, as far as
observed. Upon this thin but unmistakable layer of drift lies
some twelve to fifteen feet of loess.

Two very tortuous miniature channels with polished and
scored sides were noted. The curves were so abrupt that the
striating and polishing must have resulted from the action of
streams of glacial mud and gravel being under stress and
driven with unusual force through the confined and winding
channel.

This seems to be the point farthest south in the state where
such grooves and striae have been noted. At La Platte light
grooves and striae have been reported in the Carboniferous
limestone. In the Dakota Cretaceous near South Bend, Mr.
Charles N. Gould has observed parallel grooves which may be
glacial, or as he thinks more likely artificial, being made by the
Indians in former times when sharpening implements in the
sandy rock of this formation. In the spring a considerable area
at Weeping Water will be stripped of the overlying drift and
loess, at which time it can be examined to much greater advan-

tage than now.
ERWIN HINCKLEY BARBOUR.

THE UNIVERSITY OF NEBRASKA.

NaNO GH Oh ee VEN N hE OF BEV ONVANT ROGKS
IN WISCONSIN

THERE is an outcrop of Devonian rock on the shore of Lake
Michigan in this state, ten miles north of Port Washington and
about a mile southeast of the little village of Lake Church,
which has hitherto escaped the notice of geologists. The dis-
covery of this exposure by the writer in the summer of 1896 was
somewhat of a surprise as all the nearest outcrops of rock, to the
north, south, and west, belong to the Niagara formation. In the
neighborhood of Lake Church the heavy drift deposits, which
form high bluffs on the very edge of the lake at Milwaukee and
at Port Washington, recede quite a distance from the shore and
take the form of a series of rolling ridges which increase in
height towards the west. Between the lowest of these ridges
and the lake there stretches a sort of terrace, elevated only five
or six feet above the lake level at its eastern margin and rising
very gradually as it recedes from the shore. The rock in ques-
tion forms the floor of this terrace and crops out in various
places in the neighborhood upon the beach and under the water.
It is also uncovered in the bed of a little watercourse which
traverses the terrace. The strata are nearly level but probably
dip slightly towards the east. The rock is an impure limestone,
somewhat earthy in composition and somewhat granular or
sandy to the touch. An inconsiderable excavation has been
made in it by the owners, disclosing a thickness of about six
feet of Devonian strata, beneath which is a transition layer of
bluish shaly rock, resting on a very hard, white, crystalline lime-
stone which probably belongs to the Niagara.

About sixty species of fossils have been obtained from the
upper layers, all of which, with the exception of a single frag-
mentary dental plate of Rhynchodus, are in the form of casts
and impressions, a fact which renders their determination a matter
of some difficulty. The fauna comprises about twenty-four

313

314 CHARLES E. MONROE

species of brachiopods, twelve or thirteen of gastropods, nine
corals and half a dozen pelecypods. Orthoceras, Rhynchodus,
and Proétus are each represented by a single species; there are
scattered crinoid joints and a few other species whose generic
relations, even, have not yet been satisfactorily determined.

Among the most abundant species are: Chonetes scitulus Hall,
Stropheodonata nacrea Hall, Atrypa reticularis L. and a species of
Spivifer with a marked depression in the fold of the brachial and
a remarkably broad and strongly impressed muscular area in the
pedicle valve. Iwo or three other species, both of Spzrifer and of
Stropheodonta, are apparently represented. Stropheodonta demissa
Conrad is probably one of the latter; another is a strongly
arcuate form, with a thick shell and an almost smooth surface.
Among other species which have been identified are Cyrtina
hamiltonensis Hall (rare), Orthis impressa Hall (a single speci-
men), Atrypa spinosa Hall, Productella spinulicosta Hall, and Cono-
cardium cuneus Conrad (the three last fairly common). There
is also a species of Afdyris; one of Weristella; a Cyclonema, near
C. multilira Hall; two species of Loxonema of ordinary form; a
tapering Zurritella-shaped shell, with both revolving and trans-
verse striae, resembling but not identical with certain forms
occurring in the Devonian of Manitoba and referred by Whit-
eaves to the genus Loxonema; a Murchisonia, near M. turbinata
Schlotheim; a Zvochonema-like shell with strongly angular and
nodose revolving ridges; a Lellerophon, near B. pelops Hall or B.
newberryt Meek; a Paracyclas and a Mytilarca. Among corals
are a species of Streptelasma,; one of Zaphrentis; one of Acervu-
faria and another of an allied genus; and a species of /avostites.

The rock in which this fauna has been discovered is thought
to constitute good material for road-making. A more extensive
development of the quarry, which it is hoped will take place
before long, will furnish opportunities for more satisfactory
investigation of the fossils.

CHARLES E. MONROE.

MILWAUKEE, WISs.,
April 25, 1900.

KINDERHOOK STRATIGRAPHY

ArT frequent intervals during the past decade, there have
appeared notes on certain beds, occurring in different parts of
the Mississippi valley, which have passed under the general name
of Kinderhook. For the most part these notes have dealt with
local phenomena. In the present connection attention is called
briefly to some problems of broader significance.

Along the upper Mississippi River the formations immediately
underlying the great Burlington limestones are exposed chiefly
in two localities. One is at Burlington, Iowa, and the other at
Louisiana and Hannibal, Missouri, and at Kinderhook, Il\linois,
which is only a few miles from the last named place. Between
the two localities the distance is 125 miles. In this distance a
shallow syncline carries down the Kinderhook beds 200 feet
below the level of the stream.

The early investigations of this Burlington- Louisiana section
were carried on simultaneously at the two ends, but by different
persons. When the time came to parallel in detail the vertical
sections at the extremes difficulties arose. The various beds
could not be traced from one point to another because, for most
of the distance, the strata were not open to inspection. The
method of correlation by visible continuity was inapplicable.
Comparison by similar lithologic sequence was likewise unsatis-
factory, because the sections were so very different, and it was
impossible to tell when or in what manner the changes took
place.

When the fossils of the two localities were compared, the
results were singularly futile, so far as throwing light upon the
problem of exact stratigraphic equivalency. The organic forms
were unequally distributed. A large part of both sections had
yielded no fossil remains at all. In the northern locality the
known animal remains had been found chiefly at the very top

315

316 CJalAIIl IFS, Wes KIO VGES

of the section; in the southern, at the very bottom. As to the
exact horizons of their occurrence the literature usually gave
small clew. With most of the forms no comparison-was possi-
ble, for the facies of the two faunas were of very different types.
After an elapse of 30 years the question of the geological age
of the various beds presented itself as formidably as when first
these rocks were brought into notice.

Of late years a number of deep wells have been drilled along
the upper Mississippi River. These have enabled various geolog-
ical sections exposed at points far removed from one another to
be connected with a degree of confidence never before attained. _
In the Louisiana-Burlington cross-section, wells at Hannibal, La
Grange, Keokuk, Burlington and other points have disclosed
important features. These purely stratigraphical features are of
particular interest at the present time because of their bearing
upon the lack of geological integrity of the typical Kinderhook.

On all of the problems mentioned, the data derived from the
deep-well sections have an important bearing. Furthermore, it
is pointed out just along what lines critical evidence is to be
sought.

A few years ago the geological sections at the type locali-
ties of the several parts making up the Mississippian series of
the Carboniferous, were personally studied in order to find out
from first hands just what each really meant.t. Among these
sections were those found in the vicinity of Kinderhook, Illinois,
which were the basis of what had been long considered the
lowermost member of the Carboniferous system, and had been
widely known as the Kinderhook formation. Hannibal and
Louisiana, Missouri, which are not far away, exhibited the same
rocks even to better advantage, and therefore were regarded in
all respects as essentially typical.

As is well known, the typical Kinderhook has been regarded
as consisting of three members: A basal Louisiana limestone, a
median Hannibal shale, and a capping Chouteau limestone.

‘Principal Mississippian Section; Bull. Geol. Soc. America, Vol. III, pp.
283-300, 1892.

KINDERHOOK STRATIGRAPHY BU)

These three members retain their lithological characteristics over
broad areas, the extent of which is surprising. The distances of
continuity are so great that ordinarily doubt would be cast upon
this assumption were it not for the fact that all observations are
easily checked by the overlying Burlington limestone. While
the lithological features of the several parts of the Kinderhook
are so persistent, the faunas contained appear to be remarkably
local in nature. The existence of a large number of restricted
faunas, in place of a general one is probably the chief cause for
past failures to correlate, by the biotic method, the various
sections of the Kinderhook.

The stratigraphical relationships of the Burlington and Loui-
Siana sections at last appear to be indicated by the aid of the
deep wells drilled between the two points. These relationships
are best expressed by the following diagrammatic cross-section,
in which, however, while drawn to a scale, no allowance is made

for the synclinal attitude of the strata. What has been regarded
as the typical Kinderhook formation is included between the
heavy lines.

Immediately beneath the Louisiana limestone, the basal
member of the Kinderhook at Louisiana and vicinity, is the
Black shale of the Devonian, according to Meek and Worthen.*
In the neighborhood of Louisiana it has been called the Grassy
Creek shale. While at the town itself it only has a thickness
of about six feet, and thins out completely to the south, it is 30
feet thick on Grassy Creek, a few miles to the west. Northward,

t American Jour. Sci. (II), Vol. XXXII, p. 228, 1861.

2 Proc. lowa Acad. Sci., Vol. V, p. 63, 1898.

318 UMAR Tree LID NAIEGS)

this shale bed grows rapidly in thickness, until at Keokuk it
reaches 195 feet.

The Louisiana limestone, which is over 50 feet thick at the
type locality, appears to get thinner northward. At Keokuk it
is only Io feet in thickness, and seemingly fails altogether before
Burlington is reached. Its southern extension is not known. It
is not believed to be as extensive as Missouri geologists have
generally supposed. The Lithographic limestone of southwest-
ern Missouri is not thought to be the same. The apparent
fading out towards the north is not an unusual phenomenon
among the limestones of the region. Similar cases are known
in the Missourian series, or Upper Coal Measures, farther west.*

At Louisiana and Hannibal, the shales bearing the latter
name have a thickness of about 70 feet. This thickness is
maintained northward at least as far as Keokuk, as deep wells
show. Beyond this point at Burlington a very similar shale,
appears in the base of the river bluffs, having a thickness,
including the upper sandy portion (Chonopectus sandstone of
Weller-), of 185) feet, above) the tiverm levely | Shale) isuknowa
to extend downward at least 150 feet more, making a total
measurement, from the top of the Chonopectus sandstone, of 235
eet

The question has arisen as to how much of the Burlington
section? can be regarded as representing the Hannibal shale.
On fancied lithologic grounds solely it was early suggested by
Worthen* and White’ that the earthy fragmentary limestone, 15
to 18 feet thick, overlying the lower ‘yellow sandstone” (the
Chonopectus bed ) was the northern extention of the litho-
graphic ( Louisiana ) limestone of Missouri. This view has been
recently again alluded to by Weller.® If this were the case all

tProc. lowa Acad. Sci., Vol. VII, 1900.

2Trans. Acad. Sci., St.Louis, Vol. X, p. 57, 1900.

3Full detailed descriptions of the various sections here referred to will be found
in the lately issued volumes of the lowa and Missouri geological surveys.

4Geology Iowa, Vol. I, p. 206, 1858.

5 Boston Jour. Nat. Hist., Vol. VII, p. 212, 1860.

Trans. Acad. Sci., St. Louis, Vol. X, p. 123 1900.

KINDERHOOK STRATIGRAPHY 319

of the Burlington section below the top of the Chonopectus
sandstone would be beneath the horizon of the Louisiana lime-
stone.*

In the recent Iowa? and Missouri3 reports the basal shale as
exposed above river level at Burlington was considered as about
the equivalent of the Hannibal shale. At the same time it was
surmised that this part of the section at Burlington probably
rested directly upon certain shales found farther north, and
which were commonly regarded as belonging to the Devonian.
This, however, was merely a working hypothesis; and opportu-
nity did not present itself to carry out very far the necessary
field investigation to either prove or disprove it.

On this supposition the 235 feet of shale, of which about
one third is above the river level at Burlington, would represent
not only the Hannibal shale, but in its lower unexposed part, a
so-called Devonian shale as well. The recent discovery of a
rich fauna? considered as composed of typical Devonian types
gives strength to this idea. Still later Weller’ gives expression
to something of the same conception when he states regarding
the occurrence of the Hannibal shales in Iowa, that it is ‘‘ proba-
ble that the section at Burlington is equivalent, or more than
equivalent, to the whole of the section as known in Missouri.”
If we take into consideration the 150 feet of shales below water
level the stratigraphic evidence now presented goes far towards
proving the statement.

The deep-well sections give no indication that the Hannibal
shales, as they are known at the type locality, change materially
either stratigraphically or lithologically from Louisiana to Keo-
kuk. There is yet no reason whatever for imagining that they
should abruptly thin out entirely between Keokuk and Bur-
lington.

*Iowa Geol. Sur., Vol. X, p. 79, 1900.

2 Towa Geol. Surv., Vol. I, p. 55, 1893.

3 Missouri Geol. Surv., Vol. LV, p. 56, 1894.

4Proc. lowa Acad. Sci., Vol. IV, p. 39. 1897.

5 Trans. Acad. Sci., St. Louis, Vol. X, p. 123, 1900.

320 GQVENIMILIDS, 1s KIB VATS,

One the other hand, all evidence goes to show that the
Louisiana limestone gradually becomes thinner as the distance
increases from the type locality northward, until at Keokuk it is
less than one fifth of its original thickness. Everything indi-
cates that it has faded out completely long before the city of
Burlington is reached. If the Hannibal shales have retained any-
thing of their normal thickness, as they have in the long distance
from Louisiana to Keokuk, the horizon of the Louisiana lime-
. stone would be expected to be not far above the river level at
Burlington. No bed at or near this horizon has been found that
would correspond in lithological or any other of the characters
of the Louisiana formation. The only layer of the whole Bur-
lington section below the base of the Burlington limestone, that
at all resembles the Louisiana is the Productal limestone ( No.
3 of Keyes, No. 4 of Weller ), with a coralline zone at the base
( No. 3 of Weller ), and overlying the Chonopectus sandstone.
The lithologial characters of the two are only remotedly related.
There are strong stratigraphic reasons, however, for connecting
this stratum, as well as those above it, up to the Burlington
limestone, with the Kinderhook limestones still farther north at
LeGrand, in Marshall county, lowa. Still other grounds exist
for believing the Productal zone at Burlington to be the atten-
uated margin of LeGrand beds.*

All the stratigraphic evidence, as disclosed by the Missis-
sippi River cross-section, the deep wells along the course, and the
general geological features of the region appear to indicate,
beyond much doubt, that the Louisiana limestone actually does
become attenuated northward from the type locality, and that
the underlying Grassy Creek shales and the overlying Hannibal
shales merge north of Keokuk. If this be the correct interpre-
tation, the section at Burlington, below the top of the Chono-
pectus sandstone, including over 100 feet of shales beneath the
river level, represents considerably more than the Hannibal
shales of Missouri.

™There is, therefore, apparently little possibility of the Productal limestone
representing anything other than the Chouteau beds as exposed farther south.

KINDERHOOK STRATIGRAPHY a2

The Chouteau limestone, which finds its typical development
in central Missouri, appears to be well represented, in the north-
eastern part of the state where the typical Kinderhook is shown,
by 10 feet or more of massive earthy limestone, that is fine
grained and contains comparatively few fossils. It is sufficiently
distinctive in lithological characters to be readily recognizable
in deep-well drillings. At Keokuk, it is over 20 feet thick, and
at Burlington, if we consider the interval between the Chono-
pectus sandstone and the Burlington limestone as representing
it, about 30 feet thick. In central Iowa it is believed to be
represented by the LeGrand limestone, and is over 100 feet thick,
there being about the same development as in central Missouri.

The lithologic features at Burlington, while differing from
those farther south and at the type locality in central Missouri,
correspond very closely with the characters presented northward.
At Burlington, also, it is still chiefly limestone. Here it consists
of a thin basal coralline zone, the Productal limestone, the Spirifer
sandstone, the Gyroceras oolite and the brown Rhodocrinus
limestone. These, however, are local collectors’ names, and it is
not known how far these distinctions should be really recognized,

Independent of the purely stratigraphical characters of the
Kinderhook, as exposed along the Mississippi River, there are
certain faunal features of the formation that are not without
interest. Until now, all correlations of the Kinderhook beds
have had to be inferred from imperfect fossil data. Moreover,
the information has been so inexact for present requirements,
that the fossils have to be studied largely anew in order to find
out in just what layers the various forms occur. Only in this
way can useful and exact comparisons of the faunas be made.

Already Weller has begun, along the lines indicated, a series
of ‘Kinderhook Faunal Studies.’’ Judging from the two install-
ments already issued it is expected that there will soon be avail-
able much of the long desired information concerning the exact
stratigraphic range of the fossils, and the relationships of the
various biotic groups.

CHARLES R. KEYES.

ON WSIS TAROWABIEIS, QCOQUIRINIZING’ Ole 2 LARGE
AREA OF NEPHELINE-BEARING ROCKS ON WEEE
INQURIN SSNS IE (COVMS I (OG ILS, SUIS IMO

In a recent paper in this JouRNAL,’ Dr. Coleman has described,
under the name of Hevonite, an interesting analcite-bearing rock
from near Heron Bay, on the northeast shore of Lake Superior,
and states that although the occurrence of a dike rock of this
composition would indicate the presence of nepheline syenite in
the vicinity, no area of this rock had as yet been discovered
in that district. Many years ago, while looking over some of
- the rock collections in the museum of the Canadian Geological
Survey, at Ottawa, my attention was attracted by two specimens
of a rather coarse-grained, red rock from Peninsula Harbor,
Lake Superior, on account of the fact that their appearance sug-
gested that they might belong to the class of nepheline syenites.
Sections were made and examined at the time, but no nepheline
was found, and the investigation was not carried further owing
to lack of material and absence of information as to the exact
mode of occurrence of the rock in question.

In connection with Dr. Coleman’s paper, however, it may be
well at this time to present a few notes concerning these rocks,
as they indicate that the district in question affords a field of
much interest for petrographical study.

The first of the rocks in question was collected by Dr. Selwyn
in 1882, and is labeled ‘‘ Peninsula Harbor,’ while the second
was collected by Mr. Peter McKellar in 1870, and is labeled
‘Mount Point, S.E. side, Peninsula Harbor.” They both come,
therefore, from the same neighborhood, and probably from the
same mass. Unfortunately, the specimens cannot at present be
found, so that it is necessary to base the descriptions on the
four thin sections in my collection.

tJour. GEOL., Vol. VII, No. 5.

322

AREA OF NEPHELINE-BEARING ROCKS 323

The first of these rocks belongs to the class of the augite-
syenites, but is of a peculiar type. The augite is represented by
two varieties which pass into one another. One is a purplish-
brown augite, which frequently constitutes the inner portion of
large individuals, and shades away into an outer border of green
augite of the second variety. This green augite also occurs in
separate individuals. Both varieties have high extinction angles,
and the green variety is probably an aegerine-augite. In addi-
tion to the augite, a small amount of deep bluish-green and
highly pleochroic hornblende is present. The single sec-
tion of this rock also contains a considerable amount of a
mineral which has the high index of refraction and high double
refraction of olivine, and which is destroyed by acid with
gelatinization.

The feldspars, which with the augites make up most of the
rock, consist in part of orthoclase and in part of microperthite,
and possibly anorthoclase, and usually possess a zonal structure,
an outer border or rim of microperthite often surrounding an
individual of orthoclase nearly free from intergrowths. Small
quantities of pyrite and magnetite are also present, as also of a
deep brown, almost opaque, non-metallic mineral, which is unat-
tacked, even by prolonged treatment, with concentrated hydro-
chloric acid, and which is probably one of the rarer rock-making
minerals.

The structure of the rock is remarkable, and entirely different
from that of the ordinary augite-syenites. The feldspars are
idiomorphic, and impress their form on the dark constituents,
with the exception of the olivine. These latter occupy the inter-
sticial spaces, and are penetrated by the feldspar laths in a
manner suggestive of an ophitic structure. The character of the
augite and hornblende, as well as the abundance of the feldspar,
suggest a magma rich in alkalis.

The second specimen strongly resembles the first, but in it
the hornblende replaces the augite, and is present in large amount.
This hornblende is so intensely colored that in many cases it is
nearly or quite opaque, but when transparent has a deep

324 FRANK D. ADAMS

bluish-green color and a marked pleochroism. It has a small
axial angle, and resembles in general character the variety rich in
ferrous iron and alkalis described from the nepheline syenites
of Dungannon, Ontario, under the name of Hlastingsite.

The feldspars resemble those of the other specimen, but
there is proportionally more microperthite and a considerable
amount of an acid plagioclase. Fluor spar is also present, in
not inconsiderable amount, in the form of large, colorless grains.

The structure is the same as that of the former specimen,
the feldspars being idiomorphic, and the dark constituents
occupying the spaces between the feldspar laths.

The specimens, therefore, while not actually containing any
nepheline, have the character of certain differentiation products
of alkali-rich magmas, which are found associated with nepheline
- syenites and other nepheline-bearing rocks in other parts of the
world. .

In the Report of the Geological Survey of Canada for 1846-7,
Sir William Logan, after describing certain ‘‘traps”’ of this same
district, refers to what is apparently the same occurrence, as

follows:
“The rock above and below is composed of brownish feld-
spar and black hornblende... . it is large-grained, and the

general mass of the country constituting the Old Pic Point and
Island appears to be composed of it. Fluor spar occurs as a
disseminated mineral in some of the beds. Judging from frag-
ments on the shore, there are some beds composed of white
feldspar and occasional groups of orange red grains of elaeolite,
the whole studded with brilliant black crystals of hornblende,
forming a very beautiful rock. The general mass of these vol-
canic overflows weathers to a red, and from a distance may be
readily mistaken for the gneiss which underlies the chloritic
shales.”

Although the rocks in question are here classed as belong-
ing to the traps of the district, in the Geology of Canada pub-
lished by the Geological Survey of Canada in 1863, they are, in
a reproduction of the passage quoted above, referred to simply

AREA OF NEPHELINE-BEARING ROCKS 325

as “igneous rocks” and nothing is said about their supposed vol-
canic affinities. In the same publication also, p. 467, the occur-
rence is referred to as follows:

“On the main shore of Lake Superior, nearly north of the
western extremity of Pic Island, is a mass of syenitic rock, com-
posed of red feldspar and hornblende, with zircons which resemble
the zircon syenite of Norway.” As is well known, this latter
rock is an augite-syenite, which in Norway is intimately related
to nepheline-syenite.

As all the localities mentioned in this note are near one
another on the same stretch of coast, and in the vicinity of
Heron Bay, it seems certain that there is in this district a large
intrusion of an alkali-rich magma, differentiated into various
rock facies, among which there are some containing nepheline
and some free from that mineral, and that Dr. Coleman’s Heron-
ite is connected with the intrusion in question.

FRANK D. ADAMS.

PETROGRAPHICAL LABORATORY,
McGILuL UNIVERSITY.

PRONOUNS, OW AWE INS SIVANGIS, Ole Wels, ICis, AVG ISIN
CENTRAL S CAIN DIN ay ADA

In the Dovre region which lies to the north of Christiania the .

main divide runs in an east-westerly direction.

On the moun-

tain plateaus of this region the parent rock of much of the drift

63°n. Ll.

Fic. 1.—The Dovre region in Norway.
The arrows mark the movement of the ice.
The shaded part is the last remnant of the
great ice according to Dr.Andre M.Hansen.

is found on the southern side of
the divide;
ice had its movement upstream,

consequently the

at least during part of the ice
age.
Dr. Andre M. Hansen has
given a reasonable explanation
of this fact which may be illus-
trated by the following diagram,
L1G, Bo

The country is steeper on
the north side of the divide
(am) than on the south side
(23s).

cover, on the other hand, formed

The contour of the ice-

a rather regular curve, and the

* movement in it took place from

the thickest and highest part
(0) outward to both
Consequently on the stretch

sides.

(ca) the movement was against
the slope of the surface as indi-
cated by the largest arrow of
the diagram.

Now let us leave for a moment this question of the ice

movement and turn to another phenomenon. -

In the supper

parts of the valleys to the south of the divide, strand-lines
occur of the same kind as the much discussed “parallel roads”

326

LAST STAGE OF ICE AGE IN SCANDINAVIA 327

of the Scottish Highlands. The explanation is the same in
Norway as in Scotland; they are the beaches of lakes which
were dammed in by ice during the late glacial time. Dr. Hansen
has tried to give an elaborate account of the manner in which
this came about. He thinks that the ice melted latest where
the thickness was greatest, and that the last remnants came to

d

lie as a narrow strip of ice, a sort of “‘ice sausage,” on the slope
of the south of the divide and somewhat parallel to it (see
Fig. 1). On the diagram the shaded part shows the ice in the
last stage, and the lakes were dammed in between it and the

divide. The readers of this JouRNAL may remember that this

i
uv

Q

a0 Titties»

HiiGs 2:

explanation was hinted at in a paper by Dr. Hansen, entitled
“Glacial Succession in Norway,” Vol. IH, 1894, p. 137, conclu-
sions, by the way, to which most Norwegian geologists assent
only to a limited extent.

By his explanation Dr. Hansen has made urgent the question
at what place the last remnants of the inland ice were located.
Mr. Schiétz, professor of physics at the University of Christiania,
has criticised Mr. Hansen’s views from the physical standpoint
in a paper entitled ‘‘How will the ice divide act during the
melting of the inland ice?” printed (in Norwegian) in Myt
Magazin for Naturvidenskaberne, Vol. 34, Chr., 1895, pp. 102-111.

He demonstrates that any “‘ice sausage”’ on the slope below the
divide can come into existence only in the case that the melting
takes place so suddenly and quickly that the snow line during
the period of melting is at a greater height than the crest of
the country. If the snow line rises gradually as the tempera-
ture rises, the diminishing glaciers will concentrate at the divide.
He thinks this the most probable case, and points to the great

local glaciers which undoubtedly have descended from the

328 HANS REUSCH

divide, and to the fact that small local glaciers still exist in
the region described. If Mr. Hansen is right, the snow line
was first very much elevated, then descended below its present
limit, and more recently has ascended again to produce the
present conditions.

It seems) toy themoresent
writer that a study of the
now existing Scandinavian
glaciers makes another ex-
planationof theice-dammed
lakes more probable than
that set forth by Dr. Han-
sen. It may be remembered
that the region in question
is to be regarded as a high
plateau intersected by val-
leys.' Our ‘chief existing;
glaciers are also found in
country of the same kind,
and in accordance therewith
they present themselves as
gently-domed or shield-like
snow-fields, intersected by

1: ¥00000 valleys free of snow. This
has long been known of the

Fic. 3.—The Folgefonn glacier-field.

two great snow-fields of
southern Norway, ‘The Folgefonn”’ and ‘‘The Justedalsbrae.”
The Folgefonn, for instance, is dissected by valleys into three
parts, as seen on the accompanying map. In size the Folgefonn
is the second among the Scandinavian glaciers. The greatest is
the Justedalsbrae. Next to this comes ‘The Svartisen” (Svart
= swarthy, blackish; isen= ice ) situated under the polar circle.
Even on our latest maps this glacier has been delineated as an
unbroken elliptical snow-field with its greatest dimensions from
south to north, although Mr. Rekstad of the Norwegian Geo-
logical Survey had shown in 1891 that the snow-field is divided

LAST STAGE OF ICE AGE IN SCANDINAVIA 329

— /
a eMaMALILUULa Mn
Ghai UR =
en ™ BAIiy 5 i
ee | Be
Cayo )

sal nines’
AA / af
Ak
RY
AY
23.
yy j 4 :
J i SS
SLEW 2 Ss
ax

¥
Zt A

SSS
Sa Za
J )) x i

Fic. 5.—Glaciers descending from the Svartisen to the Glomdal valley.

330 HANS REUSCH

into two by a desert valley, the Glomdal (dal=valley). He
was the first Norwegian known to have entered the inner part of
that valley formerly known only to a few Laps, an incident which
indicates that geographical discoveries may yet be made within
Europe itself. He has described and photographed the principal

"Fic. 6.—The region in the vicinity of the main Scandinavian divide to the north
of Christiania. The line of 100 meters above the sea is shown.
glaciers descending into the Glomdal. The greatest is presented
herewith. The Norwegian Topographical Survey has of late
made a more detailed map of the region. With the aid of their
material, which has not as yet been published, the present sketch
map was made, Fig. 4.

If we now turn to the region of the old ice-dammed lakes,
we find a country well fitted for similar extensive fields of ice
and snow, with empty valleys between. The map (Fig. 6)

LASS RAGE ORMCE AGE LN. SCANDINAVIA 331

shows how the line of 100 meters encompasses narrow branching
valleys. We may easily imagine that during a certain stage of
the melting this line was the snow line and determined the
extension of the snow-fields. Some glacier descending from
one of the greater side-valleys may have stopped back the
water of the main valley and formed a lake. Mr. Rekstad says
that the river that issues from the Glomdal valley sometimes

Fic. 7.—The Daemmevand (dammed lake) in Hardanger.

rises enormously, and that the flood is probably due to the fact
that the water is temporarily obstructed by the chief glacier that
intrudes upon the valley. Norway has its Marjelen See cor-
responding to the famous Swiss lake as is well known among
geologists through Lyell’s Principles. The Norwegian glacier-
dammed lake is the Daemmevand (the blocked-up lake) in the
province of Hardanger, in the high region to the east of the
town of Bergen. From an extensive snow-field, the ‘‘ Hardanger
jokul” (jdkul = glacier) descends to a lake. On its way it
blocks up the ‘‘Daemmevand.” This lake has of late attracted
some attention, as the water sometimes breaks through the
glacier and causes sudden and destructive floods. To prevent
this the government has made a tunnel about 300 meters long

332 HANS REUSCH

through a spur of the mountain called Turumeten. This tunnel
has had the effect desired in preventing the lake rising above
a fixed level. Mr. A. Holmsen, who had the supervision of the
work, has had the kindness to communicate a sketch-map
(Fig. 7) of the surroundings of the lake, and a photograph of
the blockading glacier with a part of the lake in the foreground,

Sena
Lo pn See

- eee pe SS SSS
Wee Se 5 tl MCA Hides
hy ee ty OS a! MELTS ie yi lye
i! Hl till Nie eS in a F
LU CU Seerrny sy cua st “ay Va
= TM ltt 2, Ms
ARMM yh, Uta

Ki \ a ni th
il jj (a3 NDAs

Ayn on PP : AMV)

Pe AU) zs Dewy yea

i ne Ne
aN iy
y

Fic. 8.—The ice barrier in front of the lake Daemme, sketched from a photograph.

From a dam like this we may mentally reconstruct a barrier
capable of accounting for the lakes dammed back in olden
time in the Dovre region.

There are two English accounts of this lake, viz., that of
Mockler-Ferrymann (‘‘The Daemmevand of Rembesdals Glacier
Lake, Geogr. Jour., 1V, Dec. 1894, London, pp. 524-528) and
that of Munro (‘‘Ona Remarkable Glacier Lake formed by a
branch of the Hardanger-Jokul, near Eidjford, Norway, Proc. of
the Roy. Soc. of Edinburgh, Session 1892-3, Vol. XX, pp. 53-82).
The two Norwegian scientists, Bing and Oyen have also made

reports on the lake.
Hans REUSCH.

STRIDES TIOIR, Sy Tay DINIES

Pitta Ors whl SOL GS UMeEDING SLONES AND
VEO DS tO rh DE ViTNUNG ae Wks VATU ES 1,

In selecting a stone for building or other economic purposes,
one should be familiar with the
i Color
( Mineralogical,
) Chemical.

Tl, Suenedn, | Semone
| Transverse.

II. Composition,

IV. Hardness.
V. Elasticity.
VI. Porosity (including fissile planes).
VII. Specific gravity.
VIII. Weight per cubic foot.
IX. Effect of temperature changes.
(a) Freezing and thawing of interstitial water.
(0) Effect of extreme heat.
X. Effect of gases, | ee

XI. Quarry conditions.

There are three important methods of obtaining these facts:
(1) observations at the quarry and adjacent natural exposures ;
(2) examination of buildings, monuments, or other construc-
tions built out of the stone; (3) laboratory examination. If a
geologist were obliged to choose between the three, he would
probably consider the first method most satisfactory. The archi-
tect and builder, on the other hand, would undoubtedly choose
to examine buildings already constructed out of the stone.
However, the value of opinions based solely upon quarry obser-
vations or the inspection of buildings depend largely upon the

333

334 SIGIUES, SHOU SIL CIDIEIN HSS

judgment and experience of the observer. They lack a definite-
ness and certainty which can only be supplied by the laboratory
tests. No one of these should be considered sufficient in itself,
but each should be used in conjunction with the other two.

QUARRY OBSERVATIONS

Several important conclusions may result from quarry obser-
vations which cannot be reached through an examination of
buildings or selected samples in the laboratory. Chief among
these may be mentioned: (1) the probable injury to the stone
from quarrying, handling, and dressing; (2) the capacity of the
quarry to furnish as needed the required quantity of stone of the
desired quality; (3) the uniformity in color and mineralogical
composition, and the apparent uniformity in strength, hardness, —
elasticity, and porosity.

Stone is often more or less injured through improper methods
of quarrying and dressing or careless handling, as explained in
the previous paper.t*. One can become familiar with the methods
employed in quarrying the stone only by visiting the quarry
where the work is being carried on.

The knowledge that a quarry has the capacity to furnish as
needed the required quantity of stone of the desired quality is
an important matter. A quarry is sometimes poorly equipped
with machinery; men may be scarce; orders for stone may be
plentiful; and as a consequence inferior stone is placed upon the
market for the better grade. The situation of the quarry in
these respects can be best determined by an examination of the
quarry and its equipment.

The uniformity in the color of the stone can be quickly
determined by an examination of the quarry. If the stone dif-
fers in color at different horizons, or in different parts of the
quarry, precautions can be taken in the specifications to insure
the receipt of stone of a uniform color by-designating that it be
taken from a definite part of the quarry.

tJour. GEOL., Vol. III, No. 2, pp. 181-184.

TEE ROPER IES OF RULEDING SLONES- ELG. 335

Stone from different parts of the same quarry may differ
widely in mineralogical composition, strength, hardness, elas-
ticity, and porosity. Differences in these respects, when of
importance, may be detected through quarry observations. How-
ever, in order to ascertain these differences, one needs to be
thoroughly familiar with the conditions controlling these prop-
erties. Differences in mineralogical composition may be recog-
nized by one who is familiar with the common rock-forming
minerals.

Differences in the strength of stone result from differences
in mineralogical composition, and in size, shape, and manner of
contact of the individual grains, all of which can be made out by
an experienced observer.

Not only can an experienced person detect differences in
the qualities of stone from various parts of the same quarry, but
he can also make comparisons with stone from other known
localities.

At the quarry the unweathered stone can be compared with
that of the natural outcrop which has been exposed to the
atmosphere for many years. Comparisons based upon such
observations furnish very fair estimates of the permanence of
color and the degree of hardness, strength, and durability of the
stone. Such estimates, however, must necessarily be very gen-
eral, because of the uncertain length of time that the weathered
stone has been exposed to the atmosphere. It may have been
uncovered for centuries, or perhaps for only a few years.

In the outcrop the stone may be found bleached, stained with
brown, or discolored with white efflorescent patches. Bleaching
ordinarily proceeds very slowly and extends to no great depth,
and is therefore of little importance. Brown staining usually
indicates the presence of iron, and the white efflorescent patches
give evidence of magnesium or calcium salts.

In glaciated regions the hardness of a rock is frequently esti-
mated by the depth and extent to which the surface has been
grooved or striated. However, this is a very uncertain evidence
of hardness, being controlled largely by the condition of the

330 STUDIES FOR STUDENTS

glaciers as they passed over the region in question, and the
length of time that the surfaces have been exposed to the atmos-
phere since glaciation.

The durability of a stone is occasionally estimated from the
depth to which disintegration has extended. The extent of dis-
integration, however, has the uncertain time element in it, which
may vitiate the conclusions.

Observations on stone in the natural exposure, where disinte-
gration has not gone too far, reveal inequalities in hardness
caused by concretions, nodules, pebbles, clay seams or pockets,
and fossils. Weathering also emphasizes sedimentary and joint-
ing planes, which are obscure in the freshly quarried rock. It is
often contended by quarrymen that joints die out with depth,
but this cannot be laid down as a general rule. Some joints are
probably superficial, but others certainly penetrate to very con-
siderable depths. The farther the joints extend laterally, the
greater is the probability that they will continue to a considera-
ble depth.

A luxuriant growth of lichens on a natural exposure of rock
is frequently taken as evidence of durability. Unfortunately this
criterion of durability, when taken alone, has little significance.
An abundant growth of lichens has often been observed on the
surface of sandstone which was inherently soft. Such occur-
rences simply indicated that a crust had been formed on the
exposed surface of the stone.

If one is desirous of obtaining a considerable quantity of stone
perfectly uniform in color and texture, it is important that he
should visit the quarry to assure himself that the amount of
stone of the desired quality is obtainable. It is possible for a
quarry to be exhausted of its good stone, and for this reason, an
inspection is often a valuable precaution. On the other hand,
the stone from a certain quarry, which has a large percentage of
number one stone, may have been condemned by the public,
because quarrymen and contractor have permitted the use ofa
few interior blocks, “tor the sakesotteconomy a) inondenite
know when the best stone that a quarry produces is being

THE PROPERTIES OF BUILDING STONES, ETC. Sod

received, one should be personally acquainted with the possibili-
ties of the quarry.

OBSERVATIONS ON BUILDINGS

The inspection of constructions of long standing is generally
recognized as an important means of estimating the strength and
durability of stone. The value of such observations, however,
is often overestimated and it frequently happens that strong and
durable stone is condemned on account of careless methods of
handling and laying.

An estimate of the strength and durability of a stone from its
condition in a building should only be made after one has con-
sidered, (1) the age of the building; (a) ts sivee (g)) wae
climatic or atmospheric conditions; (4) its position ; (Ss) Wane
grade of stone used, and (6) the manner in which the stone
was quarried, handled, dressed, and laid.

The age of a building is especially important, it being worse
than folly to pass judgment on the stone in a building, unless
this is known. A stone may not exhibit any material deteriora-
tion during the first twenty-five years in a wall, although the
next ten years may show marked decay. As a rule the actual
disintegration of the stone in buildings in the United States is
comparatively little. Many that are fifty or more years old do
not exhibit the first signs of decay. The actual disintegration
is frequently so little that the observer must content himself
with searching for the beginnings of decay.

The height of a building usually increases the weight of ‘the
superstructure and hastens the rate of decay. The atmospheric
or climatic conditions, temperate, torrid, frigid, InehaainGl, Ofr
arid, will affect the permanence of a rock. A stone which
would remain unchanged for centuries in an arid region might
crumble and decay in a few years in a moist, temperate
climate.

The position of a building, in the business or residence part
of a city, protected or exposed to the storms and prevailing
winds, will affect more or less the life of the stone.

338 SINYDIUDS IROIR SINGUDIEINIES

The grade of stone that has been used in the construction of
the building under inspection should be known. Nearly every
quarry contains more than one grade of stone. However, it is
not an uncommon occurrence for the stone from an entire dis-
trict to be condemned because second or third grade stone has
not proved as satisfactory as number one stone from another
district. The poorer grades of stone are sometimes used in the
fronts of buildings or even carved for the finer parts of the
architectural work.

After the stone once becomes a part of a building people do
not stop to distinguish different grades, but charge all weaknesses
or imperfections against the quarry as a whole. Sometimes an
entire area including several quarries suffers in consequence.

It is also important to know the manner in which the stone is
quarried, handled, dressed, and laid. Much stone is still being
laid on edge, especially in veneer work. Where the bedding
planes are prominent and the stone is only of moderate strength,
this practice is dangerous. An observer should ascertain if pos-
sible whether the flaking and scaling is due to improper methods
of laying or to inherent weaknesses in the stone.

Stone used for ornamental and monumental purposes will
show deterioration in proportion to its age, position, etc., the
same as stone in the walls of buildings. For these reasons, the
same care should be exercised in passing judgment on its dura-
bility.

The oldest monuments are built out of marble, it being only
within a comparatively few years that granite has come into very
general use. Nevertheless, some of the important granite monu-
ments, in spite of the comparatively recent data of their erec-
tion, are gradually losing their polish and even now have finely
pitted surfaces. Monuments that are exposed for years to dust
laden winds frequently have their polished surfaces dulled and
the lettering obscured. The sides exposed to the direct
rays of the sun often deteriorate most rapidly owing to
the diurnal expansion and contraction caused by heating and

cooling.

TT PROPER SOB GLEDING SL ONES, 2 LG, 339

The degree of polish which a stone will take and the con-
trast of the hammered and polished surfaces can be best esti-
mated from the finished work. One should be mindful, however,
at all times, in making comparisons, not to allow the elaborateness
or excellence of the workmanship to influence the judg-
ment. Dealers sometimes oil the polished surfaces of the
monuments, which gives a brilliancy and luster not inherent
in the stone itself. For this reason a monument should
only be examined after it has been erected for six months ora
year.

In the case of stone used for highways and sidewalks much
can be learned of its strength and durability by inspecting
previously constructed walks and roadways. In these cases,
however, a just comparison can only be made when the manner
in which the highway or walk has been constructed, the amount
of traffic to which it has been subject, the character of the sub-
soil, the climate conditions, and the data of construction are
known. The rapidity and manner in which a stone pavement
wears are the important factors to be determined. An examina-
tion of pavements built out of the stone will indicate whether it
wears unevenly, is slippery, or is easily abraded.

LABORATORY TESTS

One who is fully acquainted with the mineralogical and
chemical composition, the physical characteristics of a stone,
and the climatic and other conditions to which it will be subject
when in use, can predict with a remarkable degree of accuracy,
without inspecting the quarry or examining buildings of long
standing, the results of exposure to the atmosphere. It is not
always possible to have a laboratory examination made, and fre-
quently it is unsought for by quarrymen, who often prefer to
rely upon their own statements to sell their stone.

The important laboratory tests are included under three
general classes, viz., (1) chemical; (2) microscopical; and (3)
physical.

340 SI GLDIUES INOUE (SIG OMAIN TICS,

CHEMICAL

The chemical analysis is the only exact method of determin-
ing the composition of a rock in terms of the elements that
compose it. It is also the best method of determining the rela-
tive proportions of the mineral constituents. The presence of
deleterious constituents, such as ferrous iron, bitumen, etc., and
the proportion that they bear to the total mass of the rock may
also be determined in this way.

MICROSCOPICAL

Much may be learned of the mineralogical composition and
physical characteristics of most rocks by a careful examination
of the hand specimen, especially with the aid of a magnifying
glass. Many rocks, however, are so fine grained that the min-
eralogical composition and texture can only be accurately deter-
mined by an examination of thin sections under a compound
microscope.

It is thought that the microscopical examination is of much
greater practical importance and less expensive than the chem-
ical analysis. By use of the microscope and thin sections both
the mineralogical composition and texture of a rock can be
determined with a high degree of accuracy. The relative
abundance of the different minerals and even the chemical
composition can be approximately estimated. Minerals that
are easily decomposed and liable to cause discoloration can be
identified, and the presence of cracks, strains, and gas bubbles
can be detected. A single caution should be observed in this
connection. Cracks and strains are thought to be frequently
due to stresses resulting from cutting and grinding the thin sec-
tion, on account of which care should be exercised in drawing
conclusions therefrom. The size and abundance of the pore
spaces can be estimated from the texture, closeness, and manner
of contact of the grains. All the characteristics of a rock which
contribute to its strength, hardness, elasticity, capacity to resist
alternating and extreme temperatures, and immunity from the

PAE PROPE RIMES ORB ULE DING SRONES, LTC: 341

effects of carbonated or acidulated waters, can be determined by
the microscopic examination of thin sections.

It is thought that the use of the microscope, with an intel-
ligent interpretation of the facts revealed thereby, might eventu-
ally render unnecessary the performance of the physical tests
and the determination of the chemical composition. However,
at the present time, this method is only available to the scientist
who can interpret the facts thus observed. The accuracy of
his conclusions will depend upon his judgment and experience
as a petrographer. With the public it may never supplant the
physical tests, because it lacks the quantitative element.

PHYSICAL TESTS

The purpose of the physical tests is to determine by artificial
methods the strength of a stone and its capacity to resist the
destructive agents encountered in actual use. As stated on a
previous page, the signs of decay in buildings, on account of the
improper methods of quarrying, handling, dressing, and laying
are not always evidence of inherent weakness in the stone. For
this reason the physical tests, performed in the laboratory, often
provide a more reliable basis on which to estimate strength and
durability.

It is a comparatively simple matter to determine the strength
and elasticity of a stone, both of which can be measured directly
by machinery. It is a more difficult problem, however, to
express quantitatively the durability, on account of the impos-
sibility of measuring in a few weeks or months in the laboratory
any deterioration that might take place under ordinary climatic
conditions. Further than this the conditions in nature change
from day to day, both in intensity and kind, and as a rule, there
are several instead of one agent of destruction operating at the
same time. In order to measure the effect of these agents in
the laboratory it is necessary to consider them separately, and
on such a grossly exaggerated scale that there will be accom-
plished in a brief period, what in nature would require many
years.

342 SIMGIDMES JAM: SIMOIQIEIN IES,

Estimates of the strength and durability of a stone from
physical tests are usually based upon the following determina-
tions:

1. Strength,

a. Compressive,
6. Transverse.
2. Elasticity, modulus of.

Flardness — coefficient of wear.
Specific gravity.
Porosity.

Weight per cubic foot.

Effect of Temperature changes,

a. Freezing and thawing of included water,
b. Effect of extreme heat.

8. Effect of gases,

a. Carbonic acid,

N Ow Hw

6. Sulphurous acid.

Attempts have been made to classify these tests under
“strength tests” and ‘durability tests,’ but the classifications
thus made are not logical because some of the tests have a
double significance.

STRENGTH

A knowledge of the strength of a stone implies a familiarity
with its capacity to withstand both compressive and tensile
stresses. For this reason both the crushing strength and mod-
ulus of rupture should be determined.

Crushing strength — Up to within a few years the compressive
strength test, by means of which the crushing or ultimate
strength is determined, has been used for estimating both the
durability and strength of a stone. However, a stone with a
low crushing strength may be more durable than one in which
the crushing strength is high. For this reason the crushing
strength, alone, is insufficient for estimating the durability of a
stone. In the absence of other tests the importance of the
crushing strength has been frequently overestimated.

THE PROPERTIES OF BUILDING STONES, ETC. 343

At the present time, however, it is argued by some that it is
folly to determine the crushing strength, except in cases where
the strength of the stone is very doubtful. Nevertheless, I do
not believe that it is wise to encourage the abandonment of the
crushing strength test.

Architects using stone with which they are not familiar, are
glad to avail themselves of all crushing strength data. In fact,
the only intelligible method of expressing the strength of a
stone to one not thoroughly familiar with the interpretation of
the mineralogical composition and texture, is in pounds per
square inch.

Other than this the crushing strength determinations have an
important scientific bearing upon problems in dynamic geology,
and for this reason if no other the test should be continued.

It is not uncommon for a stone to be so situated in a build-
ing that it must sustain a heavy load. In very large buildings
single columns and blocks are often required to carry huge
masses of superstructure. Bridge trusses are often supported on
blocks of stone which sustain the combined weight of the super-
structure. Before using a stone for any of these purposes it is
well to know with a fair degree of accuracy its crushing
strength.

The pressure exerted on the stone in the lower courses of a
building of ordinary dimensions is not very great. It has been
computed that the stone at the base of Washington monument
sustains a maximum pressure of 22.658 tons per square foot, or
314.6 pounds per square inch. Most architects require a stone
to withstand twenty times the pressure to which it will be sub-
jected in the wall. This factor of safety, however, would only
require a crushing strength of 6292 pounds per square inch for
stone at the base of the Washington monument. The pressure
at the base of the tallest buildings yet constructed in this coun-
try can scarcely exceed one half that at the base of this monu-
ment, or 157.3 pounds per square inch. With a factor of safety
of twenty the stone used in such positions must have a crushing
strength of 3146 pounds per square inch. There are very few

344 SAW OES ID ON SIYLOIGIN TiS)

building stones in the country that do not have a higher crush-
ing strength. It may happen, however, that owing to an unequal
distribution of the load certain stones in the wall or columns,
will be called upon to sustain twenty, or even fifty times the
natural load, in which case the crushing strength should be much
greater. All things considered, however, a crushing strength of
5000 pounds per square inch is considered sufficient for all ordi-
nary building constructions.

The crushing strength of a stone can be obtained quickly
and accurately in any laboratory which is provided with appli-
ances for cutting and dressing stone cubes and a testing machine,
for determining the compressive strength. The cubes to be
tested should measure uniformly 2 X 2 X 2 inches, this being
generally conceded to be the standard size. Smaller or larger
cubes may be used, but some authors, following the early experi-
ments of General Gilmore, still maintain that the crushing
strength per unit of area varies with the size of the cube tested.
Believing this, General Gilmore constructed an empirical formula
for the purpose of reducing all tests to pounds per square inch
on two-inch cubes. However, it has been shown to the satisfac-
tion of most persons, that this formula is neither theoretically
nor practically true. It is now believed quite generally that the
crushing strength per square inch is the same whether the cubes
tested be large or small; cubical or prismatic in shape. Until
this question is settled to the satisfaction of all it is best that all
tests be made upon two-inch cubes.

The cubes should be very carefully sawed from stone which
has not been injured by rough handling or hammer dressing.
The faces should be rubbed smooth, and the opposite sides
should be made parallel. Before the cubes are placed in the
testing machine they should be thoroughly dried and the average
area of the bearing faces determined. Thin strips of blotting
paper, wood, or lead, are often placed between the steel plates
of the machine and the bearing faces of the stone cubes, to
assist in distributing the load. It is claimed by some, however,
that this has a tendency to lower the crushing strength. The

GET ROPERIVES OR BULEDING SLONES, LTC. 345

author believes, that for the sake of uniformity, at least, it would
be best to apply the bearing faces directly to the steel plates of
the machine, a spherical compression block being used in mak-
ing the test. Record should be kept of the direction in which
the pressure is applied with respect to bedding.

The load at which the cubes are first cracked, the ultimate
strength, the perfection of the resulting pyramids, and the explo-
sive manner in which the cubes break should be carefully noted.
The crushing strength per square inch is computed by dividing
the ultimate strength by the average area of the bearing surfaces
in square inches.

Transverse strength.—The transverse strength is measured in
terms of the modulus of rupture. This is the force required to
break a bar of any material one inch square, when resting on sup-
ports one inch apart, the load being applied inthe middle. The
determination of the modulus of rupture is of far greater impor-
tance in masonry construction than would be supposed from the
very meager data available. The broken lintels, caps, and sills
which are so conspicuous in many of the larger buildings in this
country, testify to the need of a more general appreciation of
the value of this test. Many building stones that are perfectly
suited to withstand the compressive stresses in the body of
the wall, have such a low modulus of rupture as to be
unfit for use in a position where a high transverse strength
is required.

The necessary thickness of a lintel, cap, or sill depends mainly
upon the transverse strength of the stone. In order to avoid
possible danger from weak stone or unequal stresses, the doors
and windows of the heavier buildings are often arched.

For the purpose of obtaining the modulus of rupture, pieces
should be prepared by sawing, and should have a cross section
of one square inch and a length of from six to eight inches.
The sides should be smooth and the opposite faces parallel.
The pieces thus prepared should be placed in a testing machine,
in which both ends are supported and the pressure applied in the
middle. The weight required to break the sample and the

346 SILI S WHOM SINGS OLIN IES

position of the rupture should be carefully recorded. The
modulus of rupture is then computed from the following formula:

a
ee ame
31
jeaass
2bhd Me

W— concentrated load at center in pounds.
6 =breadth in inches.

a@ —depth in inches.

Z —length.

# —=modulus of rupture in lbs. per sq. in.

Modulus of elasticity—Vhe modulus of elasticity is synonymous
with coefficient of elasticity, and is sometimes defined as the
weight that would be required to stretch a rod one square inch
in section to double its length. The result is generally expressed
in pounds per square inch. It is ‘‘valuable in determining the
effect of combining masonry and metal, of joining different
kinds of masonry, or of joining new masonry to old; in calcu-
lating the effect of loading a masonry arch; in proportioning
abutments and piers of railroad bridges subject to shock,” etc.

Baker. )

One method of measuring the modulus of elasticity is by
recording the amount of compression which a two-inch cube of
stone undergoes for each increment of 500 to 1000 pounds up
to the limit of elasticity. From the data thus obtained the
modulus of elasticity is computed by use of an empirical
formula.

The value of such determinations from a commercial stand-
point are somewhat doubtful, owing to the fact they are seldom
reterreds tom by architects) ihe sparcitymomsthemcetenmina.
tions in this country is undoubtedly one reason for their
uselessness.

FHlardness—The hardness of a stone may be determined
quantitatively by the use of an abrading machine, and the results
expressed as the coefficient of wear. .The abrasion test is used
mainly for determining the wearing qualities of crushed rock for

THE PROPERTIES OF BUILDING STONES, ETC. 347

macadam but it is thought that such tests will prove valuable
and important for determining the suitability of stone for steps,
sidewalks, and flooring.

The abrading machine that is considered best suited for
determining the coefficient of wear is that used by the Wis-
consin Geological Survey, and patterned after the machine used
by the Massachusetts Highway Commission."

Specific gravity—The determinations of the specific gravity
of building stones that have come under my observation have
been based upon two very different conceptions. According to
one of these conceptions the specific gravity depends entirely
upon the mineralogical composition, and is independent of the
porosity of the stone. According to the other conception the
pores are considered a part of the stone and the specific gravity
is computed for the exterior volume. These two methods give
different results for the same stone, and have been designated
by Regis Chauvenet as ‘Specific Gravity Proper” and ‘Apparent
Specific Gravity.” Where the porosity of a stone is less than
I per cent. the two specific gravities are almost the same.
But where the porosity is 10 or 25 per cent., they are very
different.

In most discussions of building stone tests the principle laid
down by Professor J. C. Smock? that, the specific gravity of the
particles or mineral species composing the rock mass, determines
that of the stone has been followed.

The practical engineer, however, objects to this method,
because he cannot compute the weight of the stone per cubic
foot directly by multiplying by 62.5, the weight of an equal
volume of water. Several contemporary writers on building
stones, however, have unfortunately made the mistake of deter-
mining the ‘specific gravity proper” and then computing the
weight per cubic foot by,multiplying this directly by 62.5. For

* For description of this machine see the Report of the Massachusetts Highway
Commission for 1899, pp. 59, 60.

? Bulletin of New York State Museum, Vol. II, No. 10, p. 374, PROFESSOR J. C.
SMOCK.

348 SOMES VO RS SAUD ENTS:

example one author gives the following as the results of his
experiments on three different stones."

“| ait Weight in lbs. Per cent. of
umber SPEC Cer awaty per cubic foot water absorbed
COOMA earrenatraratoneteceveletel see orornae 2.6236 163.50 18.07
CPOE GBM Aebateere ats rric ps ote nero nae 2.6166 163.07 32.62
CRAB Ola oes aicree Bee eethe eyes 2.5380 158.17 8.71

It will be observed as a result of these experiments that the
stone which absorbed 18.07 per cent. of water weighed more than
the one that absorbed only 3.62 per cent., although the differ-
ence in specific gravity is only .007.

Another author says: ‘If we find that a stone has a specific
gravity of 2.65 .... we get its weight by simply multiplying
255. Dy 2:05) which eaves USP 05.02...) 4) sinetiMssstavemlenme
reference is made to the “specific gravity proper’’ and not the
‘apparent specific gravity.”’ Results obtained in this way would
obviously be incorrect. Similar inaccuracies in the determina-
tion of the specific gravity and weight per cubic foot, occur in
other published reports, but those above quoted suffice as illus-
trations.

I believe that the specific gravity should be determined on
the principle laid down by Professor J. C. Smock3 and that the
“apparent” specific gravity should only be used in computing
the weight of ithe stone per cubic foot, ) Phere is mo; incon
sistency in this, in so much as the commercial weight considers
only the external volume and does not consider the stone as a
geometric solid. At least there should be a recognized uniform
method of computing the specific gravity of stone.

The specific gravity proper of a rock can only be obtained
by weighing the samples in air, at a definite temperature, after
all interstitial water has been expelled; then weighing them,

t Bulletin of New York State Museum, Vol. II, No. 10, Table, p. 358, by FRANCIS
A. WILBER.

2 The Building and Decorative Stones of Maryland. Maryland Geological Sur-
vey, Vol. II, p. 119, GEo. P. MERRILL.

3 Joi.

WIEN PROPE RIES OF BULEDING STONE SLE. 349

completely saturated with water, in water; and finally dividing
the weight in air by the difference. These ideal conditions of
absolute freedom from interstitial water in the one case, and
complete saturation in the other, are difficult to obtain. Never-
theless, if accurate methods are employed and care is exercised
in manipulation it is thought that a high degree of accuracy. can
be attained.

As previously stated, it is advisable to perform all tests on
two-inch cubes. In obtaining the specific gravity, the samples
should be cleaned by carefully washing, and dried for twenty-
four hours in a hot air bath at a temperature of 110° C. The
samples should then be weighed and the weights recorded in
grams to the second decimal place. The samples should then
be transferred to a large bottle or other glass receptacle, corked
tightly, and sealed. This bottle should then be transferred to a
water bath having a temperature of 100°C. Three glass tubes,
one leading to an air pump, another to a manometer, and a third
to a basin of boiling water are passed into the bottle through
holes in the cork. By means of the air pump, the air in the
bottle should be exhausted until the pressure, as indicated by the
manometer attachment, is lowered to at least one twelfth of an
atmosphere. The pressure should be maintained at this point
while distilled water at a temperature of 100° C is drawn into
the bottle through the third tube. This tube which conveys the
water should be partly rubber and should extend to the bottom
of the bottle. A stop cock is used to regulate it. By starting
the air pump and operating the stop cock at the same time it 1s
possible to keep the pressure nearly constant and at the same
time draw any desired amount of water into the bottle. By this .
process, the air in the pores is gradually replaced by the water
which fills the vessel from below. After the cubes are com-
pletely covered with water, they should be allowed to remain in
the bottle twenty-four hours maintaining a pressure of one
twelfth of an atmosphere.

The saturated samples should then be quickly transferred to
a basin of distilled water and removed to the weighing room.

350 STUDIES FOR STUDENTS

After removing the samples from the basin, the water adhering
to the surface should be deftly removed by the use of bibulous
paper, the samples transferred to the scale pan, and quickly
weighed.. Through the transference of the samples from the
basin to the scale pan there are two sources of error, one is
through the use of bibulous paper, and the other through
evaporation. No plan has yet been devised to avoid these
SOunees of efron, wheretore theyslall and, Vudementyormrnc
operator must be depended upon.

After these weights are recorded the samples should be
suspended by a silk thread in distilled water and again weighed.
After this weight is recorded the samples should be transferred
to a hot air bath and dried at a temperature of 110° C. until the
interstitial water has been entirely expelled. The samples are
again weighed and the results recorded. From the weights
thus obtained the specific gravity is determined by dividing the
average of the two dry weights by the difference between the
average dry weight and the weight of the cube suspended in water.

The apparent specific gravity can be readily obtained by
subtracting the weight of the sample suspended in water from
the weight of the sample saturated with water and dividing the
average dry weight by this difference.

Porosity and ratio of absorption.—These terms have been used
interchangeably as applying to the percentage of the weight of
the absorbed water to the average weight of the dry sample.
This ratio, however, is not the percentage of actual pore space,
but simply the relation between the weight of the rock and the
weight of the water absorbed. The term porosity should only
be applied to the percentage of actual pore space in the rock
while the ratio of absorption should be restricted to the percent-
age of the weight of the absorbed water to the average weight
of the dry sample. The former gives the volume relation and
the latter the weight relation. To my knowledge no American
writer has computed the actual pore space or porosity of
building stones. However, I believe that this determination is
more important than the ratio of absorption.

THE PROPERTIES OF BUIEDING STONES, ETC. By 5)

The method of obtaining the porosity which is ordinarily
employed is as follows: The sample to be tested is heated at a
temperature of 100° C, to drive off the moisture. After cooling,
the sample is weighed, and then slowly immersed in distilled
water. After bubbles cease to be given off, the sample is
removed from the water and the surface quickly dried with
bibulous paper, after which the specimen is again weighed.
The difference in weight gives the increase due to the absorp-
tion of water. This difference divided by the weight of the dry
stone is taken as the ratio of absorption or porosity.

Several errors are apparent in this method. The interstitial
water is not easily expelled at a temperature of 100° C. To
expel the moisture in a moderate length of time, the stone
should be dried at a temperature of 110° C. Further, the samples
cannot be completely saturated “by immersing in distilled
water until bubbles cease to be given off.” Finally the method
of computation gives the ratio of absorption and not the percen-
tage of actual pore space or porosity.

The porosity of a stone should be obtained in the following
manner, using the determinations made in performing the
specific gravity tests. The average weight of the dry sample
should be subtracted from the weight of the saturated sample, to
obtain the weight of the water absorbed. This, multiplied by
the specific gravity of the stone, will give the weight of a
quantity of stone equal in volume to the pore space and of the
same specific gravity as the stone tested. This weight divided
by the weight of the dry stone will be the porosity or actual
percentage of pore space.

The ratio of absorption can be obtained by dividing the
weight of the absorbed water by the weight of the dry stone.

In another part of this paper I have shown that neither the
porosity or ratio of absorption, alone, indicates the value of a
stone for building purposes. It was pointed out that the size of
the pores is by far the more important consideration. This can
be estimated roughly, when the size and shape of the grains and
percentage of pore space are known. If only the. ratio of

252 STUDIES FOR STUDENTS

absorption is available the calculations of the size of the pores
are liable to be less accurate.

For scientific purposes, other than determining the quality of
a stone for building, the porosity, and not the ratio of absorption
is the factor sought after. The porosity test will result in a
higher percentage than the ratio of absorption, and may there-
fore meet with disfavor among quarrymen. However, when it
becomes known that the value of a stone cannot be estimated
from its porosity except when the size of the pore spaces is known,
objections will cease. In all cases it is thought that the porosity
should be determined in preference to the ratio of absorption.

Weight per cubic foot of stone —The weight of stone when it is
first quarried, depends upon its specific gravity, the amount of
pore space, and the water content. For a given stone, the only
fluctuating element is the water content. In the more porous
rocks this will vary at different seasons of the year and will
depend upon the thoroughness with which the rock has been
seasoned. Any determination of the weight per cubic foot of
a stone which includes an indefinite quantity of interstitial water
is unscientific and unsatisfactory. Determinations thus made
depend upon a number of conditions, changes in any one of
which will give a different result. The only constant weight is
that of the dry stone.

The commercial weight of a stone may be obtained in two
ways. First, by weighing directly a known volume of the stone
which has been thoroughly dried at a temperature of in@ Cos
second, by computation from the data obtained in determining
the porosity. By the second method, the weight of a cubic foot
of stone can be obtained by multiplying the weight of a cubic
foot of water by the specific gravity proper of the stone and sub-
tracting therefrom the weight of a mass of stone, equal in vol-
ume to the pore space of the given rock and of the same specific
gravity.

A simpler method would be to compute the apparent specific
gravity as directed above and multiply by 62.5, which should
give the same result.

TIER EROPERILE SIO BUILDING STONES, ETC 353

Effect of temperature changes.— The durability of a stone
depends very largely upon its capacity to withstand temperature
changes. Such changes may affect the mineral constituents of
rock through expansion and contraction, or they may cause the
interstitial water to freeze and thaw, on account of which the
strength of the stone may be materially lessened.

Very few tests have thus far been made to determine the
effect on building stone, of the alternate freezing and thawing of
interstitial water. The importance of such experiments has never
been questioned, but the difficulty of manipulation and the many
conditions which need consideration before conclusions can be
drawn from the quantitative results, have had the effect of almost
excluding these tests from the experiments on building stone.

The effect of alternate freezing and thawing may manifest
itself in three ways: first, cracks may form ; second, small par-
ticles or grains may be thrown off from the surface occasioning
a loss in weight; third, the strength of the sample may be
lessened. The first result is very seldom observed in testing
samples in the laboratory, owing to the careful selection of the
pieces tested. The other two, however, usually occur and can
be measured quantitatively.

Two methods, known as the natural and the artificial, have
been employed to determine the effect of alternate freezing and
thawing of the interstitial water. The natural method is to soak
the samples with water and alternately freeze and thaw them, a
- few or many times, at the convenience of the operator. The
artificial method is to saturate the stone in a boiling solution of
soluble salt, such as sodium sulphate, and then allow it to dry.
As the water evaporates the salt crystallizes and expands, produc-
ing stresses similar to those which result from freezing water.
It appears to me that the only instance in which it is excusable
to use this method is when there is no opportunity to freeze the
samples under conditions which more nearly accord with those
which occur in nature.

For the purpose of testing stone according to the natural
method, the operator should use two-inch cubes as in the

354 SLITS, IROVE SIMPMNIIN TES

previous experiments. If the tests are made during the winter
months when the temperature is below the freezing point, the
samples can be saturated with water, cooled to nearly the freez-
ing point, and then placed out of doors. If freezing tempera-
tures do not prevail in the climate where the experiments are
being performed, access may be had to a cold storage build-
ing where the necessary temperature may be obtained. Freez-
ing mixtures may also be used to produce the desired tempera-
ture.

The samples to be tested should first be thoroughly cleaned
and dried in a hot air bath at a temperature of 110° C. and
weighed. After the samples are thoroughly saturated with dis-
tilled water, after the manner outlined in the specific gravity
test, they should be cooled almost to the freezing point, taken
from the water and removed tothe place of freezing and allowed
to remain for twenty-four hours. The samples should be thawed,
saturated, and frozen alternately each day for a period of thirty
or forty days, after which they should be placed ina hot air
bath and dried at a temperature of 110° C. They should then
be removed to the weighing room and weighed. This final
weight subtracted from the first gives the loss in weight. The
samples should be examined to discover any cracks that may
have formed as a result of the freezing.

Finally the frozen cubes should be crushed in a testing
machine to determine their compressive strength. The results
thus obtained should be compared with the strength tests made
on unfrozen cubes of the same stone.

The loss in weight during a period of thirty-five days has
been found to be due mainly to the removal from the surface of
small particles which were previously loosened, in the process of
cutting the sample. Many of the grains at the surface of sand-
stone samples which have been sawed or hammer-dressed are
partly loosened. Such grains fall away from the mass of the
stone very easily. The pressure which is supplied by the freez-
ing water, which fills the cracks and pores near the surface, is
abundantly able to accomplish this.

TENE IAAOV MIE IMIRS (OND Se UPI WONE PS IMO rs\) PING. 355)

Naturally, sedimentary rocks, such as sandstone, have more
loose grains at the surface than the igneous rocks or finely crys-
talline limestone. However, in any case, alternate freezing and
thawing for a period of thirty-five days will scarcely result in
anything further than the removal of the loose particles from
the surface. If the process is continued for another thirty-five
days it is prqbable that in the case of sandstone the loss during
this period will be far less than that of the first period. Even
though the loss should be as great, the results could not be
justly compared, except between the same kinds of stone.

To my knowledge, the loss in crushing strength due to freez-
ing has not received the least consideration by any previous
writer on building stones. As inferred above, I believe that the
tests heretofore made to determine the loss in weight are of
comparative little value in estimating the effect of freezing and
thawing on the durability of a stone. The determination of the
loss in crushing strength is obviously more important. It is evi-
dent that if a stone is saturated with water and frozen while a
portion of the pores are still filled with water and the process is
repeated a score or more of times, the adhesion of the particles
will be weakened. It is not reasonable to suppose that the
strains produced can be measured by the immediate loss in
weight. It is plausible to suppose that the deterioration can be
better measured by the loss in strength.

Experiments performed in the preparation of the report on
the ‘ Building Stones of Wisconsin”’ confirm my impression
regarding the value of the crushing strength test applied in this
manner. I feel quite confident that this test is more important
than the determination of the loss in weight, and should, I
believe, eventually take precedence in the testing of building
stones.

Extreme heat—Very few tests have been performed to ascer-
tain the effect of heat or cold when applied directly to stone,
yet it is known from observation that rapid and extreme changes
in temperature weaken a rock and often cause disintegration.
In large cities, the capacity to withstand extreme heat is one of

356 STUDIES FOR STUDENTS

the essential qualities of a good building stone. In the conflagra-
tions which have occurred in many cities, brick, stone, and
wooden structures have suffered alike. Granite and brick walls
have crumbled into shapeless masses, while iron beams and
girders have been melted and twisted into all conceivable shapes.

A comparatively low temperature destroys some materials,
while others are barely affected at a temperature above the melt-
ing point of copper. Most building materials, however, are
destroyed when subjected to a very high heat.

It is known that rocks are poor conductors of heat, and for
this reason the outer shell of a block may be very highly heated
while the interior is comparatively cold. If a block is quickly
cooled after heating, contraction of the outer shell takes place,
and the differential stresses occasioned thereby rupture the rock.

The destruction caused by a conflagration is largely increased
by streams of water which are thrown onto the burning buildings
in an attempt to extinguish the flames. If the fire occurs in
winter the effect is still further intensified by the freezing of the
water.

Few experiments have thus far been performed to determine
the temperature which the different kinds of stone will stand
without injury. It has, however, been demonstrated that stone
will withstand a much higher temperature when heated and cooled
slowly than when heated and cooled rapidly.

The easiest method to test the capacity of a stone to with-
stand heat is to place two-inch cubes in a muffle furnace and
gradually heat them from a low to a high temperature. By
using a standard pyrometer the temperature can be gauged and
the visible effect of any increase in heat can be noted. Samples —
should be tested not only to ascertain the effect of gradual heat-
ing and cooling, but they should also be removed from the
furnace and suddenly cooled by plunging into cold water.

Limestone and dolomite are injured mainly through calcina-
tion, although when suddenly cooled they flake at the corners.
Coarse grained granite is often shattered throughout its mass.
Medium grained granite flakes at the corners, while the compact,

| To be inserted between pp. 356 and 357, May-June number, 1899. |

LIMESTONE QUARRY ABOVE FLORENCE FLINT. BLUE SPRINGS, NEB.

EXPOSURE OF FLOKENCE FLINT IN A QUARRY EAST OF WyYMORE, NEB.

GEOLOGICAL MAP |
OF |
SOUTH-EASTERN |
NEBRASKA |
TM COAL MEASURES,

PERMIAN

E = =] pakora GRour

A GEOLOGICAL SECTION OF THE NEBRASKA PERMIAN FROM BEATRICE SOUTH
AND EAST TO THE KANSAS LINE.

RTE VEROPEP RITES OF BULEDING STONES, ETC. 357

fine grained varieties are often traversed by sharply defined
cracks. In contrast with the limestone and granite, sandstone
has all outward appearance of being very little injured by extreme
heat. However, it is often so soft after being subjected to
extreme heat that one can crumble it between the fingers. The
extent to which a coarse grained sandstone has been injured by
extreme heat cannot be determined until the strength of the
stone has been actually tested. All the stone that has been
heated to a high temperature emits the characteristic ring, and
scratch of brick. The cause for this may be found in the loss
of the water of composition by the minerals of the rock.

Experiments seem to indicate that there are few, if any, stones,
whether they be granite, limestone, or sandstone, that will effect-
ually withstand a temperature of 1500° F. A rock with a uniform
texture and a simple mineralogical composition apparently
suffers the least injury when subjected to high temperatures.

It would be interesting to know the loss of strength occasioned
by each increase in temperature of 100 or 200° for the different
kinds of building stones. This can only be determined by a
careful series of experiments, and it is hoped that in the future
some one will undertake this task.

The effect of sulphurous acid gas—Limestone, dolomite, and
marble are the only kinds of stone which are to any extent
injured by sulphurous acid gas. To determine the effect of this
gas upon dolomite or limestone, two-inch cubes are dried at a
temperature of 110° C. and carefully weighed. They are then
placed in a wide mouthed bottle, in the bottom of which is placed
a beaker of water to keep the air moist. The bottle is sealed
and each day sufficient sulphur dioxide is transferred into the
bottle to keep the atmosphere saturated. The samples should
be allowed to remain forty-four days in this atmosphere saturated
with sulphur dioxide. After being removed from the bottle the
samples should be washed and thoroughly dried at a temperature
of 110°C. They should finally be weighed and the loss in
weight determined. The percentage of loss in weight is taken
as the result. The loss in this case is due mainly to the

358 SAGES, SHOVE SLA GLOIBIN TES

magnesium and calcium salts which collect at the surface and
are dissolved by the water when the samples are washed.

Effect of carbonic acid gas—TVhe effect of carbonic acid gas
on limestone is determined in the same manner as that of
sulphurous acid gas. The samples are dried at a temperature of
110° C. and weighed. They are then placed in a wide mouthed
bottle which is filled with carbonic acid gas. A beaker of water
is placed in) the bottle to keep thevatmosphere, moist ken
being treated for forty-four days the samples are removed,
washed, and weighed. The percentage of loss in weight is
taken as the result.

Sulphur dioxide and carbon dioxide probably do not at any
time exist alone in the atmosphere. The effect of these gases
acting together or in conjunction with the many less abundant
gases of the atmosphere may produce very different results than

when acting separately.
Bok BUCKEYE
GEOLOGICAL AND NATURAL History SURVEY.
Madison, Wis.

[ID IAOIRIAIE

AN unsigned article in Sczence (June 22) entitled “Sigma X1
at the American Association for the Advancement of Science,”
calls attention approvingly to a movement to associate meetings
of this Greek-letter society with those of the Association. The
rapid rise of the Sigma Xi in American universities is cited, and
it is affirmed that ‘‘as an honor society it promises to take a
leading part in our universities in which science holds a promi-
nent place.” It is urged that ‘it has become a representative
honor society for the ablest students of science in the institutions
where it is established.” Respecting its intent, the following
authoritative quotation is made: ‘In establishing a new chapter

_. in each case we should make sure that we entrust the
power of distributing the honor of membership only to such per-
sons and institutions as are capable of giving the education and
training necessary to the carrying on of scientific investigation.”

It is scarcely necessary to make these quotations to show
that the fundamental feature of the society is the promotion of a
class distinction based on academic preparation. However laud-
able this may be, in itself considered, it would seem to be inhar-
monious with the fundamental purpose of the Association, which
is the development and dissemination of science among all people
without regard to race, age, sex, or previous condition of intel-
lectual servitude. From professional relations the writer should
not be inappreciative of the value of university training aya! Olt”
academic achievement. Nevertheless, it seems to him that the
purposes of the Association are unqualifiedly democratic and
that the spirit of science is equally so, and that therefore the
only distinctions which the Association should foster or sanction,
if it fosters or sanctions distinctions at all, are those which are .
based solely upon scientific productiveness. And this produc-
tiveness should be honored quite irrespective of its connection

359

360 EDITORIAL

with the fortunate conditions of academic appointments and
opportunities, or with the adverse or even hostile conditions
under which much good science has been developed. The move-
ment therefore to connect the meetings of the Sigma Xi with
those of the Association seems incongruous.

As set forth in another article in the same number of Sczence,
some fifteen special scientific societies have already become cor-
related with the Associationand have much increased the complex-
ity of the proceedings. This movement seems to bean inevitable
consequence of the differentiation of scientific work, and is scarcely
less than necessary to the continued success of the Associa-
tion, but it has already brought some inevitable conflict of inter-
ests and not a little congestion of programs and appointments.
Between these and the increased number of social functions, it
_has already come to pass that there is little time left for that
personal conference and that informal sociability whose basis is
‘‘shop talk,’’ which formed so large a factor in the attractiveness
of the earlier meetings of the Association. If now in addition
to these laudable complications, the attention of a considerable
number of the members of the Association is to be diverted in the
interest of an academic honor society and a precedent established
for the meeting of other societies whose basis is not strictly con-
genial to that of the Association, it is not clear where the limit
of congestion will be found.

Between the lines of the article referred to, the imagination
is tempted to read a hint of a desire for that rank and dominance
in the Association which the members of Sigma Xi attained in
university circles, and it is not unnatural to anticipate that the
fraternity might unconsciously play a part in Association politics
not unlike that for which Greek-letter societies are famous
throughout the university world. To those who pride them-
selves upon rank and band themselves together because of rank
it is not unnatural that official expressions of rank should be
sought through the unconscious influence of fraternization.

It is not altogether foreign to the subject of this discussion
to note the increasing encroachments of formal social functions

EDITORIAL 361

upon the meetings of the Association and not less perhaps upon
the meetings of the Geological Society of America. Without
doubt a certain measure of formal contact with general society
is helpful to the ends sought by the Association. At the same
time it must be recognized that formal social functions are
largely the province of the leisure class and that from the very
nature of the case they must remain so, for leisure and the
means of leisure are prerequisites to their effective cultivation.
Equally from the nature of the case, the devotees of science do
not usually belong to the leisure class because real success in
science involves strenuous endeavor and an almost unlimited
devotion of time. The diversion of time to social functions
during the meetings of the Association should, therefore, be
zealously watched and restrained within limits which are com-
patible with the efficient conduct of the primary purposes of the
Association. Particularly is this true of the Geological Society
which has no organic relation to general society. The move-
ment in the direction of social formality has already crowded
hard upon the point where the first requisite preparation for a
meeting of the Association or of the Geological Society ts the
packing of a dress suit, and the second is the preparation of an
after-dinner speech, preparations that are none too congenial to
the great mass of hard workers in science.

ae sic:

VENUES:

The Illinois Glacial Lobe. By FRank LEvEeRETT, Monograph
XXXVIII, U. S. Geological Survey, pp. 817. Plates XXIV,
9g figures. Washington, 1899.

This is one of a series of monographs in course of preparation by
the Glacial Division of the United States Geological Survey, whose
purpose is to set forth the salient features of the glacial formations
preparatory to more detailed mapping by quadrangles, which the sur-
vey is undertaking, and by counties and other appropriate divisions,
which many of thestates are prosecuting. In a sense it may be said to
be the first monograph of the systematic series. “Two other monographs
_ have been published, namely, that on Lake Agassiz, by Mr. Warren
Upham, and that on the Glacial Gravels of Maine, by Professor George
H. Stone, but these are special treatises on phenomena of exceptional
interest and only indirectly form a part of the systematic series intended
to cover the glacial area. The plan of the Survey departs somewhat
widely from that prevalent in Europe where glacial work proceeds
largely by minute studies of small areas without previous determination
of the great features and broader classifications which can only be
worked out by connected studies over large areas. The method of
the United States Geological Survey has been to determine first these
grand features and leading classifications and then descend in natural
order to local details and more refined studies. Local mapping pro-
ceeds at great disadvantage without such preliminary determinations,
for such is the nature of the glacial formations that these larger
expressions of the phenomena of the period are very imperfectly
expressed within any restricted area, and are quite beyond satisfactory
interpretation unless the studies are extended beyond them.

The general reconnaissance work of the survey was essentially
completed some years ago by the geologist in charge and the work of
preparation of the monographs, as the second step of the plan, is now
well under way. Besides the monograph under consideration, the
manuscript of an additional one has been submitted and work upon a
third is in progress.

362

REVIEWS 363

The products of the Illinois glacial lobe constitute a natural mono-
graphic theme, for the differentiation of the border tract of the ice by
the topographic influences of the trough of Lake Michigan gave the
lobe a quite distinct individuality. In the monograph, however, for
convenience the field is rather arbitrarily limited on the north where
the products of the Illinois lobe become complicated on the east side
with those of the Huron-Erie and the Saginaw lobes and on the west
side with those of the Green Bay lobe. This limitation, however,
does not seriously affect the unity of the theme. This lobe was given
precedence because its field embraces the most southerly reach of the
great ice mantle and because its products are unusually well deployed.

The author’s abstract of the monograph which follows, sets forth its
contents better than could be done by another.

Chapter I. Introduction.— The Illinois glacial lobe formed the south-
western part of the great ice field that extended from the high lands east and
south of Hudson Bay southwestward over the basins of the Great Lakes and
the north-central states as far as the Mississippi valley. It overlapped a
previously glaciated region on the southwest, whose drift was derived from an
ice field that moved southward from the central portion of the Dominion of
Canada as far as the vicinity of the Missouri River. This southwestern part
of the eastern ice field, being mainly within the limits of the State of Illinois,
has received the name Illinois Glacial Lobe.

The results of earlier studies by Chamberlin, Salisbury, and others are
noted, and the plan of investigation is set-forth. A brief explanation of the
method of numbering townships 1s presented.

Chapter IIT. Physical features The variations in altitude are set forth
in a topographic map and also in tables, and the marked increase in altitude
of certain parts of the region because of drift accumulations is considered.
The conspicuous reliefs of the rock surface are briefly touched upon, and the
preglacial valleys receive passing notice. Profiles and maps are extended
across the bed of Lake Michigan as well as border districts, and the inequali-
ties of the lake basin are briefly discussed.

Chapter IIT. Outline of time relations or glacial succession.—A sketch
of the major and minor divisions of the drift sheets and of the intervals
between them is accompanied by a brief explanation of the basis for the
classification adopted.

Chapter IV. The Illinoian drift sheet and its relations.— The Illinoian
is the most extensive drift sheet formed by the Illinois glacial lobe and
receives its name because of its wide exposure in the State of Illinois. The
evidence that the Illinoian drift sheet should be separated from the outlying
and underlying drift is briefly set forth. The aspects of the Illinoian drift

364 REVIEWS

sheet are then discussed, its topography as well as its structure being con-
sidered. In connection with this drift sheet a very adhesive clay known as
“ gumbo,”’ which caps it, is described and the questions of its relation to this
drift sheet and to the overlying loess are considered. A detailed description
of the border of the Illinoian drift sheet is then given, which is followed by a
description of the moraines and other drift aggregations back from the
border.

Remarkable instances of the transportation of rock ledges are noted.
The striz pertaining to this invasion are discussed in some detail. The
effect of this ice invasion and its drift deposits upon the outer-border
drainage is touched upon, but the detailed discussion of the influence of the
drift upon drainage is deferred to a later chapter. The chapter closes with a
discussion of the deposits which underlie the Illinoian drift sheet.

Chapter V. The Varmouth sotl and weathered zone—— A well-defined
soil and weathered zone which appear between the Kansan and Illinoian
drift sheets in the overlap of the latter upon the former are described, and
sections are represented which show clearly the relations to these drift sheets.
The amount of erosion effected during the interglacial stage is also considered.
The name Yarmouth is taken from a village in southeastern Iowa, where the
interglacial features were first recognized by the writer.

Chapter VI. The Sangamon soil and weathered zone.— Another well-
defined soil and accompanying weathered zone which appear between the
Illinoian drift and the overlying loess are described. The name Sangamon
is applied because these features are exceptionally well developed in the
Sangamon River basin in Illinois and were there first noted by Worthen in the
early reports of the Illinois Geological Survey.

Chapter VIL. The lowan drift sheet and associated depostts— The
name Iowan was applied by Chamberlin to a sheet which is well displayed in
eastern Iowa and which had been brought to notice by McGee. The chapter
opens with the discussion of a drift sheet of a similar age which was formed
by the Illinois lobe, its extent, topographic expression, and structure being
considered. The relation of this ice lobe to the Iowa ice lobe, and the rela-
tion of each to the great loess deposit of the Mississippi basin are then con-
sidered, after which the loess is discussed. The problem of the mode of
deposition of the loess forms the closing topic.

Chapter VIII, The Peorian soil and weathered zone (Toronto formation).
The name Toronto formation, suggested by Chamberlin, for interglacial
deposits exposed in the vicinity of Toronto, Canada, may prove to be applica-
ble to a soil and weathered zone which appear between the Iowan drift sheet
or its associated loess and the Shelbyville or earliest Wisconsin drift sheet
which overlies the Iowan. Exceptionally good exposures of a soil and
weathered zone at this horizon in the vicinity of Peoria, Ill., make it seem

REVIEWS 365

advisable to apply the name Peorian, while the relations of the Toronto
formation remain uncertain, Other exposures as well as those near Peoria
are discussed. A marked interglacial interval between the Iowan and Wis-
consin stages of glaciation may also be inferred by a comparison of the
outline of the ice sheet at the Iowan stage of glaciation with that of the out-
line at the culmination of the Wisconsin stage. It may also be inferred by
a change in the attitude of the land, by which better drainage conditions were
prevalent in the Wisconsin than in the lowan stage.

Chapter IX. The early Wisconsin drift sheets. —The Wisconsin drift,
named by Chamberlin from the state in which it was first recognized as a dis-
tinct drift, is characterized by large morainic ridges and comparatively smooth
intervening till plains which have been thrown into two groups, known as the
early Wisconsin and late Wisconsin. In the first group the moraines form a
rudely concentric series, which are well displayed in the northeastern part of
Illinois, but are largely overridden by the moraines and drift sheets of the
later group in districts farther east. The outer border of the second, or late,
Wisconsin group is so discordant with the moraines of the first group that
there seems in this feature alone sufficient reason for separation.

The several morainic systems of the early Wisconsin group are taken up
in succession from earlier to later, the distribution, relief, range in altitude,
surface contours, thickness and structure of the drift, and the character of the
outwash being considered. In connection with each morainic system the
associated till plains are discussed, attention being given to the surface
features and to the structure and thickness of the drift. In northern I[]linois
the several morainic systems are merged into a composite belt so complex
that it is difficult to trace the individual members.

The several moraines and their associated sheets of till do not appear to be
separated by intervals so wide as are found between the I]linoian and Iowan
or the Iowan and Wisconsin drift sheets. Indeed, instances of the occurrence
of a soil or a weathered zone between Wisconsin sheets are very rare.
There may, however, have been considerable oscillation of the ice margin.

Chapter X. The late Wisconsin drift sheets.— The basis for separation
from the early Wisconsin is first considered, after which the several morainic
systems and their associated till plains are taken up in order as in the dis-
cussion of the early Wisconsin drift. An interpretation of the Kankakee
sand area is attempted, though several questions connected with it still remain
open. The chapter closes with a discussion of the striz found within the
limits both of the early and of the late Wisconsin drift.

Chapter XT. The Chicago outlet and beaches of Lake Chicago.— That a
body of water once extended over the low districts bordering the southern end
of Lake Michigan and discharged southwestward to the Des Plaines and
thence into the Illinois River has been recognized since the early days of

366 REVIEWS

settlement, and several papers discussing the beaches and the outlet have
appeared. ‘The latter has long been known as the Chicago outlet, because it
led away from the site of that city. The lake has recently been given a
name in harmony with that of the outlet (Lake Chicago).

After reviewing the previous reports and papers, the Chicago outlet is
described in some detail. The several beaches of Lake Chicago are then
taken up in order from highest to lowest. The chapter ends with a discus-
sion of the present beach of Lake Michigan.

Chapter XII, Influence of the adrift on drainage systems and drainage con-
ditions.— It is shown that many drainage systems are entirely independent of
the preglacial lines, while others are independent only in part, a considerable
part of their courses being along the lines of old valleys. The development
of drainage systems is shown to be much farther advanced en the Iowan and
Illinoian drift sheets than on the Wisconsin. This is found to be due to dif-
ferences in age, and not to natural advantages for discharge. The Wisconsin
is, on the whole, more favored by uneven surface for the rapid development
of drainage lines than the Illinoian. The several drainage systems are dis-
cussed in considerable detail.

Chapter XIII, Average thickness of the drift in [linots.— inois affords
an especially good opportunity for the estimate of the thickness of the drift,
because of the large number of well sections obtained, and because of the
comparative smoothness of the region. The inequalities of the rock surface
beneath drift plains may be estimated by the study of neighboring driftless
tracts, as well as by borings and outcrops within the drift-covered area.
There are thus two quite different methods by which the average thickness
of the drift may be ascertained.

The first method here used is that of averaging the results of borings and
outcrops. These are averaged in each township in which the distance to
rock is known, and the results are then combined for the average of all the
explored townships. Consideration is then given to the distribution of the
explored townships in reference to drift plains and moraines and to preglacial
uplands and valleys, and necessary corrections are made. By this method
the thickness of the drift is found to be not less than roo feet, and it may be
120 feet or even more.

The second method, based upon a comparison of the Illinois drift area
with the neighboring driftless tracts, gives 129.3 feet as the average thickness,
or slightly more than the highest results obtained by the first method. Com-
bining the two methods, the average thickness of the drift of Illinois can be
placed at not more than 130 feet and not less than 1oo feet.

An attempt is made to estimate the part contributed by each ice invasion,
but the data prove to be scarcely complete enough for a good estimate. It
is found that the general thickness within the limits of the Wisconsin drift is
40 to 45 feet greater than in the portion of the state outside.

REVIEWS 367

Chapter XIV. The wells of Illinois —This chapter aims to present all
the reliable well records obtained within the state which throw light upon
the deposits penetrated, as well as upon the character of the water supplies.
In addition to the wells which terminate in the drift, there are included many
which extend deeply into the underlying rock formations. This necessitates
a classification of the underground waters and a description of the several
rock formations penetrated, including a discussion of the attitude of the
strata. The essential conditions for obtaining artesian wells are considered,
and also the relation of the drift to the ordinary wells. There is a brief
discussion of gas wells, confined mainly to those obtained in the drift. A
tabulation of sources for city water supply is then presented, after which there
appears a detailed discussion of wells, taken up by counties.

Chapter XV. Soils——The sources of soil material are first discussed.

_An attempt is then made to classify the soils according to their origin. Eight
classes are recognized as follows: Residuary soils, bowlder clays, soils, grav-
elly soils, sandy soils, bluff-loess soils, silts slowly pervious to water, fine silts
nearly impervious, peaty or organic soils.

The matters of chief general interest will doubtless be found in the
classification of the glacial series, in the changing configuration of the
ice at its successive stages, in the differences of the deposits at the
different stages, and in the estimate of the average thickness of the
drift.

In the matter of classification, the monograph presents the latest
and fullest expression of the conclusions toward which investigations
in the interior have been steadily tending for the past decade. The
classification offered is not regarded as final, either in the sense of
including all the possible great divisions, or in the complete charac-
terization of those recognized, but it clearly lies in the line of a true
and ultimate classification. Fifteen stages are recognized, six of which
are based upon notable glacial advances, five represent notable inter-
vals of deglaciation, and four are based upon lacustrine stages after
the beginning of the abandonment of the region by the last ice-sheet.
The age of the oldest glacial formation is regarded as many times
that of the latest ; and the oldest interglacial intervals are also believed
to be many times longer than the later ones. In a word, the oscilla-
tions appear to have been large in the earlier stages and to have
grown less and less during the progress of the period. This newer
view of the relative ages of the successive epochs, sustained as it
appears to be by the progress of research in Europe, must be looked
upon as one ofthe most important advances of recent years, for

368 REVIEWS

it affects profoundly nearly all of the larger questions of glacial
history.

The distinction between the ages of the several glacial sheets
is founded upon careful estimates of the amounts of erosion they
have respectively suffered, upon the depths and extent of the weather-
ing process as exhibited alike in the clays and in the pebbles and
bowlders, upon the degree of constructive mineralization in the form of
segregates and general induration of the deposits, upon the extent of
interglacial accumulations of soil, peat and similar deposits, and upon
the nature of the life which occupied the region between the glacial
stages, together with incidental criteria of more special nature and
limited application. When it is considered that the broad sheet of
Kansan till, which shows indubitable evidence of having been spread
out as an approximately plane sheet, has been so thoroughly eroded
over very large areas that only remnants of the original plane remain
_ here and there, it is impossible for the candid mind to resist the con-
viction that it is very widely separated in age from the later drift-
sheets which have been merely ditched by the water courses, leaving
scattered over the broad, scarcely modified surfaces, multitudes
of shallow basins which a few feet of cutting would completely
drain.

While not new, the monograph brings out into sharp definition the
lobate character of the ice margin at all of its stages. At the same
time it shows that there was a change in the configuration of these
lobes at different stages. It is perfectly clear from the general nature
of these configurations that they are fundamentally dependent upon
the topography of the region they occupy and of that which lies back-
ward along the line of glacial invasion. At the same time there are
some anomalies which, while not defiant of topography, do not clearly
show their dependence upon it and indicate that other factors than
topography were involved in determining the development of the ice
lobes. These other agencies are very likely climatic, but they have
not yet been deciphered. The most notable of these anomalies are
the peculiar forms assumed by the Iowan drift and the shifting in
the contours of the lobes between the earlier and later Wisconsin
stages.

Closely allied to this variation in configuration is a remarkable
variation in the mode of action of the ice at different stages to which
the monograph contributes a large mass of data. The earlier drift-sheets

REVIEWS 369

are spread widely over the country without evidences of pro-
found abrasive action upon the pre-existing surface, not that such
action was absent, but it was far less vigorous than in the later stages.
In harmony with this milder action upon the face of the country
invaded, the drift-sheet itself was spread much more uniformly than
in later times and pronounced morainic ridges are much more rare,
and when present are much feebler and less characteristic. At the
same time, the glacial drainage appears to have been much less vigor-
ous and in some instances surprisingly lacking in vigor. These phe-
nomena are among the most suggestive that yet await causal explana-
tion.

By far the most careful and trustworthy estimate of the average
thickness of the drift which has heretofore been made in this country
is embraced in chapter x1ll of this monograph. Not only are the
data much more ample and better distributed than those that have
heretofore been at command, but they have been analytically classified
and discussed by more critical methods. The most difficult element
of the problem is the drift embraced in the preglacial valleys, the
depth and configuration of which it is difficult to estimate. This has
been attempted, however, along two different lines which give essen-
tial concordant results, and it is a fair presumption that the total esti-
mate of the mass of the drift of the region investigated is a not
distant approximation to the real facts. How far the territory of the
Illinois glacial lobe is representative of the average thickness of the
drift throughout the glaciated region cannot now be determined, for
if the great Canadian tract be embraced, as it should, our knowledge
is best defined by emphasizing its limitatations ; but the average thick-
ness in Illinois may rudely represent the average thickness for areas
similarly situated near the border of the glaciated area, but even this
cannot be confidently affirmed.

The work of Mr. Leverett is conspicuous for the judicial attitude
of mind which eminently controls it. The emotional factor is held in
marked abeyance and the intellectual factor suffers little trammeling
from predilections. At the same time the large area covered by
critical study testifies to an industry which could not have been greatly
enhanced by emotional enthusiasm. The monograph will be best
appreciated by those who are most familiar with the ground.—T. C. C.

370 REVIEWS

Preliminary Report on the Copper-bearing Rocks of Douglas County,
Wisconsin. By ULyssks SHERMAN Grant, Ph.D. Wisconsin
Geological and Natural History Survey, Bulletin No. VI.
Economic Series No. 3, pp. 55. 1900.

The report is the result of field work during the summer of 1899,
and deals in a preliminary way with the St. Croix and Douglas copper
ranges of Douglas county, Wisconsin. It contains four geological
maps and several illustrative plates. Chapter 1 outlines the geology
of the county and contains a sketch of the three rock series repre-
sented; namely, the Cambrian, the Upper Keweenawan, and the
Lower Keweenawan. The Lower Keweenawan consists of igneous
rocks, largely basic lava flows with a few interbedded conglomerates.
The copper deposits are usually at or near the contacts of the flows,
and the author has given some of the characteristics by which the con-
tacts may be known. The Upper Keweenawan consists of conglomer-
ates, sandstones and shales, lying apparently conformably upon the
igneous beds and dipping southeast at low angles. The Lake Superior
sandstone underlies the northern part of the county, and consists
essentially of quartz sand, but in some places becomes conglomeratic,
and in others clayey. or shaly. Its junction with the Lower Kewee-
nawan is marked by a fault of considerable displacement along which
the traps are shattered. Chapter 11 describes some of the more impor-
tant outcrops of the St. Croix range and chapter 111 treats the Doug-
las range in a similar manner.

The last chapter is a “brief discussion concerning the mode of
occurrence of the copper, where to search for copper, and the value of

the deposits.” ‘This chapter is of special value to the prospector and
the investor. On pages 53 and 54 are given several analyses of copper-
bearing rocks from the two ranges. R. D. GEORGE.

Upper and Lower Huronian in Ontario. By ARTHUR P. COLEMAN.
Bulletin of the Geological Society of America, Vol. XI,
pp. 107-114. 1900.

In his work as geologist for the Ontario Bureau of Mines the author
has gathered much material bearing on the problem of the Huronian
in Ontario. In tracing the Michipicoten iron range it was found that
the band of siliceous rock associated with it, and generally resembling

REVIEWS 371

sandstone, passes at times into cherty and jaspery and quartzitic facies.
The same association of siliceous rock and iron ore is found near Pic
River, near Rainy Lake and on Rainy River, and near Rat Portage.
Jaspery material like that of Michipicoten is found interbedded with
iron ores near Lakes Wahnapitae and Temagami, between Sudbury
and the Ottawa River. ‘‘If, as seems probable, these jaspers are the
equivalents of the western Huronian sandstones, we have a definite
horizon, traceable from point to point across the whole northern end
of the province” which will be ‘fa most valuable thread with which to
unravel the much disturbed and complicated series of Huronian in
Ontario.” The conglomerates frequently found near the iron-bearing
series and containing sandstone, chert, or jasper, identical with those
of the iron-bearing series, have a similar range from east to west across
the province and are thought to mark the greatest break in the Huro-
nian series, or, in other words, to form the basal conglomerate of the
Upper Huronian.

The author shows that if these conclusions are well founded we
have ‘‘a means of correlating the widely separated and very different
looking rocks mapped as Huronian in Ontario. Applying these con-
clusions to the Shoal Lake district, a part of Lawson’s Keewatin is
of Huronian age. They may also lead to a more certain correlation
of the pre-Cambrian rocks of Ontario and the Wisconsin- Minnesota
region.” R. D. GEORGE.

Mesozoic Fossils of the Yellowstone National Park. By YT. W.
Stanton. An extract from ‘Geology of the Yellowstone
National Park,’ Monograph XXXII of the U. S. Geological
Survey, Part II, Chapter XIII. Washington, 1899.

This chapter forms a valuable contribution to our knowledge of
the Mesozoic faunas. The collection of invertebrate fossils described
in it consists of seventy-eight species, having a distribution as follows:
thirty-one are Cretaceous, forty-six are Jurassic, and one is possibly of
Triassic age. The last specimen, a species of Lzvguda resembling Z.
brevirostris of Jurassic age, occurs in the Teton formation which occu-
pies the stratigraphic position between the known Carboniferous and
the undoubted Jurassic. This paleontologic evidence is considered
too slight to form the basis of a correlation of the Teton with the Tri-
assic of other areas.

372 REVIEWS

The Jurassic assemblage forms the most important element of the
collection. The two chief fossiliferous areas are: the one in the north-
west corner of the Park, on the head waters of the Gardiner and Gal-
latin Rivers; and the other on the slopes of Sheridan Peak and
farther southwest of Snake River. Two zones, characterized more by
lithological than faunal peculiarities, are to be recognized, but the fos-
sils belong to a single fauna.

The upper zone is marked by an arenaceous limestone yielding an
abundance of Rhynconella gnathophora, R. myrina, Ostrea strigilecula,
Camptonectes bellistriatus, and C. pertenuistriatus. The lower zone is
characterized by calcareous clays and marls containing the majority of
the above forms associated with Pleuromya subcompressa, Pholadomya
Aingt, and Gryphea calceola var. nebrascensts.

I found very similar zones in the Freeze-Out Hills of Wyoming,
but they were characterized by slightly different assemblages of fossils.
The upper zone consisted of clays and arenaceous limestones contain-
ing Pentacrinus astertcus in abundance, and Asterias dubium, Camptonec-
tes bellistriatus, C. (extenuatus) pertenuistratus, and Ostrea strigtlecula.
In the lower zone occurred clays and marls with calcareous nodules
yielding Astarte packardt, Pinna kingi, Pleuromya subcompressa, Phola-
domya kingt, and other forms. Gelemnites densus and Pentacrinus astert-
cus is common to both zones.

As these zones are both extremely narrow, are composed largely of
clastic material, and contain an assemblage of fossils in many instances
common to both, I think the conclusion that but a single fauna is rep-
resented is the correct one. This conclusion in regard to the Yellow-
stone region Dr. Stanton extends to the entire Jurassic formation of
the Rocky Mountain region, and concludes as follows: ‘The strati-
graphic relations and the geographic distribution of the marine Juras-
sic of the Rocky Mountain region are in favor of the idea that all of
these deposits were made contemporaneously in a single sea.”

A thin stratum of limestone in a position above the Jurassic beds
and not far below the base of the Cretaceous section contains fresh
water gastropods and Unios. ‘The formation which contains this lime-
stone is referred with considerable doubt to the Dakota. It is thought
that it may be the equivalent of the Kootenai or Como. A similar
limestone stratum occupying approximately the same stratigraphic
position is found in the Como of Wind River, of the Black Hills, and
the writer found it also in the Freeze-Out Hills. In all these localities

REVIEWS Be

it contains a fresh water fauna consisting of gastropods and Unios, and
in some instances species common to two or more localities.

The Colorado formation is represented by a characteristic fauna,
consisting for the most part of Inocerami. The Montana formation
is recognized, but its divisions are not easily differentiated. It seems
probable that only the lower part of the Montana is represented.

In all, thirteen new species are figured and described. The major-

ity of these belong to the Jurassic.
W. N. Locan.

The Glacial Gravels of Maine and their Associated Deposits. By
GEORGE H. Stone. Monograph XXXIV, U. S. Geological
Survey, 499 pp., 52 plates, 36 figures. Washington, 1899.

The enthusiastic pursuit of kames and eskers through the forests of
Maine without official aid, in the later seventies, by Professor Stone,
led to his engagement for a monographic study of all the glacial
gravels of that phenomenally rich region by the U. S. Geological
Survey. The results appear in this monograph. It would be an
error, however, to overlook the second half of the title, for much
attention is given to the formations associated with the glacial gravels,
and tributary to their formation, so that the volume falls little short of
being a monograph on the Pleistocene deposits of Maine.

So far as present knowledge extends, two regions surpass all others
in the richness of their esker or osar phenomena— Maine on this con-
tinent, and Sweden on the eastern. This singular distribution is per-
haps due to a critical relation between the general slope of the land
surface in these regions and the minimum gradient at which glacier
ice flows effectively, so that a condition of approximate stagnation was
assumed in the closing stages of glaciation and the internal drainage
lines of the ice sheet were permitted to develop with exceptional facil-
ity. However that may be, Maine is certain to be the classic field for
esker studies in this country.

The plan of the volume embraces a preliminary discussion in which
the fundamental facts of surface geology as illustrated in Maine are set
forth with considerable fullness (chapters 1, 11, and 111). The opera-
tive agencies are discussed in close connection with the phenomena
described. This is followed by a general description of the systems of
glacial gravels (chapters 1v, and v). By systems is to be understood

374 REVIEWS

those connected series of gravel ridges that are interpreted as the
products of individual drainage systems of the ice sheet, the products
of each river system being a gravel system. Some forty odd systems
of this kind are recognized besides several less defined series and
numerous branches and individual eskers, making on the whole a most
phenomenal record of glacial drainage. The description of these
occupies 170 pages.

The classification of the gravels and associated deposits and a dis-
cussion of their genesis follows and constitutes essentially the remain-
der of the volume (chapters v and vi, 224 pages). The discussion
of the genetic element is elaborate and detailed. Something of the
range of special subjects may be gathered from the following special
themes: Quantity of englacial débris; distinction between englacial
and subglacial tills; the origin of drumlins; the relations of the
marine gravels; bowlder fields and bowlder trains; single or multiple
glaciation in Maine; the relation of the glacial waters to the glacial
sediments ; the sizes of the glacial rivers of Maine; the zones of the
Maine ice sheet ; englacial streams; the directions of subglacial and
englacial streams under existing glaciers ; the internal temperatures
of ice sheets; the basal waters of ice sheets; basal furrows as stream
tunnels; the genesis and maintenance of subglacial and englacial
channels ; the forms of glacial channels ; extraordinary enlargements
of glacial river channels; the directions of glacial rivers compared
with the flow of ice; the relations of glacial rivers to the relief forms
of the land ; sedimentation in places favorable or unfavorable to the
formation of crevasses; glacial potholes; the formation of kames
and osars; the bowlders of the glacial gravels; comparative studies.
on the glaciation of the Rocky Mountains and on the glaciers of
Alaska; the modification of the glacial gravels by the sea; the short
isolated osars or eskers; the hillside osars or eskers; the isolated
kames or eskers ending in marine deltas; isolated osar-mounds not
ending in marine deltas; the disconnected osars; the relations of
glacial gravels to the fossiliferous marine beds; retreatal phenomena
of the ice; causes of non-continuous sedimentation within the ice
channels ; the continuous osars and their comparison with discontin-
uous Osars ; were osars formed by subglacial or superglacial streams ?
tests of subglacial and superglacial depositions; special features and
their explanation.

REVIEWS Alls

The illustrations are numerous and add greatly to the value of the
text, and the large list of maps set forth the remarkable distribution of
the gravel systems.

The work is characterized by enthusiasm and a pervasive desire
to explain in fullness and detail all of the phenomena presented. The
observational and the rational go hand in hand and each lends interest

to the other.
Te eae:

Lower Cambrian Terrane in the Atlantic Province. By C. D. Wat-
corT, Proceedings of the Washington Academy of Sciences.
Vol. I, pp. 301-339.. February 14, 1900.

The object of the paper, as stated by the author, is to show the
stratigraphic relations and successions of the Cambrian faunas of the
Atlantic province. In the author’s correlation paper on the Cam-
brian (Bull. 81, U. S. Geol. Surv. 1891), reference is made to unsolved
problems of the Cambrian of this province. Mr. G. F. Matthew’s
study of these problems has led him to conclusions not in accord with
those tentatively set forward by Mr. Walcott. He finds the Etchemin-
ian beds at Hanford Brook unconformably below the Protolenus zone
and regards them as a pre-Cambrian Paleozoic terrane, and makes a
twofold division of the Cambrian of the Atlantic province as follows :

Dictyonema fauna.
Upper Cambrian, - - - Peltura fauna.
Olenus fauna.

Paradoxides fauna.

Lower Cambrian, - - - , Newfoundland species described.
| Protolenus fauna.

Mr. Walcott, having made a careful study of the Hanford Brook and
other localities cited by Mr. Matthew in support of his position, notes
the absence of Etcheminian débris in the overlying St. John quartzite,
the absence of an irregularly eroded surface on the Etcheminian beds,
and the evidence of overlap of these beds on the subjacent Algonkian,
and holds that the patchiness and variation in thickness of the Etche-
minian may be the result of deposition of sediments upon a very irreg-
ular sea-bottom, and not of erosion as held by Mr. Matthew. Mr.
Walcott believes the distinctive features of the Etcheminian fauna
pointed out by Mr. Matthew do not necessarily separate it from the

376 REVIEWS

Lower Cambrian. The paper closes with the following conclusions :

“‘(a) The ‘ Etcheminian’ terrane of Matthew is of Lower Cam-
brian age.

““(6) The Olenellus fauna is older than the Paradoxides and Pro-
telenus fauna of the Middle Cambrian.

““(c) The Cambrian section of the Atlantic Province of North
America includes the Lower, Middle, and Upper Cambrian divisions as

defined by me in 1891.”
R. D. GrorceE.

Forest Reserves. Part V of the Nineteenth Annual Report of the
United States Geological Survey. HEnry Gannett, Chief of
Division, Washington, D. C., 1899.

This report consists of the following parts: The forests of the
United States, by Henry Gannett; Black Hills Forest Reserve, by H.
S. Graves ; Big Horn Forest Reserve, by F. E. Town; Teton Forest
Reserve, from notes by F. S. Brandegee; Yellowstone Park Forest
Reserve, from notes by F. S. Brandegee; Priest River Forest Reserve,
by J. B. Leiberg ; Bitterroot Forest Reserve, by J. B. Leiberg; Wash-
ington Forest Reserve, by H. B. Ayers; Eastern Part of Washington
Forest Reserve, by M. W. Gorman; San Jacinto Forest Reserve, by
J. B. Leiberg ; San Bernardino Forest Reserve, by J. B. Leiberg ; San
Gabriel Forest Reserve, by J. B. Leiberg: Forest conditions of
Northern Idaho, by J. B. Leiberg; Pine Ridge Timber, Nebraska,
by N. H. Darton.

According to the report there are in the United States, exclusive of
Alaska, 1,094,496 sq. miles of wooded land, or in other words 37 per.
cent of the total area is wooded. The total value of the forest product
of the country for 1890 was 800 million dollars which is an amount
slightly in excess of its mineral production. The total amount of
sawed lumber consumed was 23,500 million feet B. M., and the amount
used for fuel was 180,000 million feet B. M.

The sources of injury to forests are classed under the categories
of fires, winds, lightning, insects, and wasteful methods of lumber-
ing. The necessity for better forest management is urged in order
to prevent waste, and to establish forests in the place of those being
depleted for legitimate purposes. It is urged that the object of forest
management should be to produce forest products in as short a time

REVIEWS 377.

as possible, to establish if possible a system of forestry which will pro-
duce lumber timber in less than 150 years, and mine timber in less
than roo years.

The principal subjects discussed in the several divisions of the
report embrace the topography, the limits, the agricultural lands, the
mining and the forests of the reserves. Other topics include the water
supply, parks species of timber, classification of timber, amount of
available timber, and means of transportation of lumber.

The report is furnished with an excellent set of illustrations and
maps. It is a valuable contribution, well calculated to accomplish the
purposes for which it was written, z. ¢., to furnish as full data as possi-
ble concerning our forests, and to waken a desire for their preservation.

W. N. Locan.

Geology of Narragansett Basin. By N. S. SHacer, J. B. Woop-
WORTH and A. F. ForrsteE. Monograph XXXIII, U. S.
Geological Survey, pp. xx + 394. 1900.

The Monograph is divided into: Part I, General Geology of the
Narragansett Basin, by N. S. Shaler; Part II, Geology of the Northern
and Eastern Portions of the Narragansett Basin, by J. B. Woodworth,
and Part III, Geology of the Carboniferous Strata of the Southwestern
Portion of the Narragansett Basin, with an account of the Cambrian
deposits, by Aug. F. Foerste.

The stratified rocks of the basin range from Cambrian to Carbon-
iferous. The structure of the basin makes it appear probable that it
originally contained an extensive development of pre-Cambrian rocks.
Upon these were laid down the lowest Cambrian beds. The Middle
Cambrian is not represented in the region south of Braintree. ‘The
Upper Cambrian is represented only by pebbles of quartzite in the con-
glomerates. While only the Lower Cambrian is found in situ, pebbles
of Middle and especially of Upper Cambrian are so abundant as to lead
to the statement that “there appears to have been nearly continuous
deposition in this field throughout the Cambrian period.” The
Silurian and Devonian do not appear to be represented in the Narra-
gansett Basin. Upon the Cambrian strata and the eruptive granites
come the Carboniferous strata which occupy the greater part of the
_ basin. It is probable that the earliest Carboniferous rocks of the basin
are the upper part of the Coal Measures, and it is possible that the upper
conglomerates of the basin may be Permian. The basin was probably

378 REVIEWS

partly formed before Carboniferous time. Professor Shaler believes
that east of the Appalachians there were developed during Carbonifer-
ous times a great series of erosion troughs which by sedimentation and
subsidence became centers of quaquaversal orogenic movement, result-
ing in foldings with axes variously inclined to one another within the
same trough. The truncated remains of the folds so produced are to
be seen at various points along the Atlantic seaboard. That these
erosion troughs were river valleys and estuaries is suggested by their
lack of parallel or other definite arrangement such as is seen in the
Appalachians, as well as by the character of the deposits they contain.
The Narragansett basin is one of these ancient erosion troughs in which
the folds were of the anticlinal and synclinal type. The present aver-
age structural depth of the basin is' placed at 7000 feet, but it is assumed
that this depth is due mainly to folding resulting from accumulation of
deposits. [he source of the bulk of the sediments of the basin was
the immediately surrounding granitic, trappean, schistose and other
rocks. ‘There are also many quartzitic pebbles of Cambrian age in the
conglomerates but the source of the similar pebbles of the drift is con-
sidered unsettled. In discussing the glacial history of the region Pro-
fessor Shaler expresses the view that this district was one of extensive
and long continued glaciation during the Carboniferous period and
that the important features of the upper stratified rocks are due to
glacial action.

In the economic section the soils, coals, and iron ores are discussed
at considerable length. Recent subsidence in the immediate vicinity
of the basin has caused flooding of old valleys. This and the thick
covering of drift have rendered geological work difficult, and the
delimitation of formations uncertain. The volume represents much
detailed work accomplished in a region presenting more than ordinary
difficulties. There are many well placed plates and figures to illustrate

ithestext: R. D. GEORGE.

On the Lower Silurian (Trenton) Fauna of Baffin Land. By
CHARLES SCHUCHERT. Proceedings of the U.S. National
Museum. Vol. XXII, pp. 143-177, with plates XII to XIV.

At the request of the author, Mr. J. N. Carpender and others (who

accompanied the Seventh Peary Arctic Expedition as far as Baffin Land
in 1897,) made collections of fossils from Silliman’s Fossil Mount at

REVIEWS 379

the head of Frobisher Bay. The fossils are well preserved and many
of them are now in the U. S. National Museum. The paper gives a
brief summary of the geology of the region as gathered from reports
by those who have either visited it or have examined collections from
it. The Lower Silurian fossils so far collected are of Trenton and
Utica age, and strata containing these faunas are widespread in eastern
Arctic America. So far as known they rest upon the pre-Cambrian
rocks and are overlain by beds of Niagara age. Of the 72 species
known from the locality of Silliman’s Fossil Mount 28 are restricted
to it. Of the remaining 54 species, 41 are found in the Manitoba-
Minnesota-Wisconsin region and 17 in the New York-Ottawa region.
A comparison of the 54 species found elsewhere with those from
definite stages in Minnesqta shows that 1o are found in the Birds-eye
(Lowville), 17 in the Black River, 38 in the Galena, and 11 in the
Cincinnatian.

The close resemblance of the Minnesota Galena to the Silliman’s
Fossil Mount formation may in large part explain the close identity of
the faunas. In the summary, page 175, the author says: ‘‘ The Baffin
Land fauna had an early introduction of Upper Silurian genera in the
corals Halysites, Lyella and Plasmopora. In Manitoba similar con-
ditions occur in the presence of Halysites, Favosites, and Diphy-
phyllum. The Trenton fauna of Baffin Land shows that corals,
brachiopods, gastropods, and trilobites have wide distribution and are
therefore less sensitive to differing habitats apt to occur in widely
separated regions. On the other hand the cephalopods and particu-
larly the pelecypods, indicate a shorter geographical range. The
almost complete absence of Bryozoa in the Baffin Land Trenton con-
trasts strongly with the great development of these animals in Minne-
sota and elsewhere in the United States.”

The paper is a valuable addition to our knowledge of the Ordo-

vician faunas of eastern Arctic America.
R. D. GEORGE.

The Freshwater Tertiary Formations of the Rocky Mountain Region.
By W. M. Davis. Proceedings of the American Academy
of Arts and Sciences, Vol. XXXV, No. 17, March, 1900.

In this very timely paper Professor Davis gives voice to a growing
change of opinion regarding the specific mode of origin of the most

380 REVIEWS

characteristic class of formations of the Rocky Mountain Tertiaries.
During recent years not a few geologists, here and there, have
expressed a disposition to regard some of the deposits usually assigned
to lakes as the products of stream action or “sheet wash,” or of a
combination of these with lake deposition. To the reviewer, who is
among these dissenters, the favorite illustration of such modes of
deposition is the present and recent accumulation in the Great Valley
of California where several forms of subaérial aggradation are con-
joined with lacustrine and marine deposition. This newer mode of
interpretation has been applied to a notable series of formations dis-
tributed at intervals from the Medina, and even the Keweenawan, to
the Lafayette and the recent deposits of the great basins of all the
continents, particularly the arid basins. The great red terranes, with
their associated products of desiccation and saline concentration,
especially, have seemed to the reviewer attributable to such combined
action, since a basin of saline concentration carries in its very terms
the idea of a basin of detrital lodgment whose central part may be an
area of subaqueous deposition but whose border is almost inevitably a
zone of subaérial accumulation. The doctrine of non-lacustrine basin-
aggradation, as it lies in the mind of the reviewer, has its most dis-
tinctive application to tracts of relative aridity, for it is in these,
chiefly, that the conditions of subaérial lodgment preponderate over the
conditions of subaqueous deposition, except in the case of aggrading
river bottoms near base level which are undergoing a depression of
gradient by deformation. In an arid basin-tract the precipitation is
likely to be greatest on the elevated rim, and there it is often spas-
modic, taking the form of cloudbursts and similar intensified forms.
The gradient is also highest, as a rule, in the rim zone. These form a
combination of agencies which result in an exceptional transportation
of detritus down the slopes of the basin rim followed by a marked
reduction of power of transportation as the flatter part of the basin is
reached; for there the flood loses its power by lowered gradient, by
spreading, by absorption, and by evaporation. Deposition is the
usual consequence. In a humid region, the conditions are largely
reversed; the streams augment in volume as they flow over the basin-
plain and the power of transportation is more or less fully maintained.
If the basin be a closed one the accumulated waters arising from the
excess of precipitation over evaporation soon cover the basin floor with
a lake which occupies the territory that in an arid region would be

REVIEWS 381

covered in large part with subaérial detritus. In a humid region with
free drainage no great thickness of detritus can usually be built up on
the floor of a basin without increasing the gradient so as to suspend
the process of aggradation, unless movements of deformation or
changes of sea-relationship intervene to renew and perpetuate the
conditions of aggradation. This of course may happen, but it is
rather to be classed as an accidental intervention than as a systematic
process.

The presumptions therefore seem to lie on the side of lacustrine
deposition, with incidental fluvial aggradation, in humid regions, while
in arid regions they lie on the side of fluvial aggradation, with inciden-
tal lacustrine deposition. ‘To the reviewer, therefore, the question has
a specific climatic relationship and this relationship seems much the
most important phase of the subject. Given the same humidity, and
the ratio of lacustrine to fluvial deposition is dependent on surface
adjustments of a local nature. Given the same surface adjustments,
and the ratio of lacustrine to fluvial deposition is dependent on states of
humidity or aridity. But the humidity or the aridity of an area large
enough to have geological importance, implies atmospheric states that
are a function of the whole atmosphere, and of its modes of circulation,
and hence has far-reaching significance.

If these considerations have any validity, the question which
Professor Davis pointedly raises regarding the Rocky Mountain Terti-
aries, as a specific example of the class under question, deserves the
most critical attention. The value of an academic discussion, which is
often unwisely underrated by the working field geologist, lies chiefly
in deploying the problem and laying the groundwork for discrimi-
native observations. Professor Davis seems to be altogether correct
in pointing out a lack of critical observation and interpretation in
most previous studies of the Tertiaries in question, and his discussion
can hardly fail to call forth incisive studies upon these formations.
Obviously their true character can only be determined by such critical
field studies. A first step is the establishment of criteria of discrimi-
nation between lacustrine and fluvial deposits; by no means an easy
task where the products of relatively shallow lakes are to be distin-
guished from those of rivers, which is really the critical case. It is
not clear that the criteria given in the paper will always hold good,
but there are several additional ones that may be brought into service,
such as the distribution of the remains of land animals in the midst of

382 REVIEWS

the basin, the occurrence of marsh-formed or land-formed lignites in
similar situations, the interstratification of beds of gypsum or other
desiccation products, and analogous criteria that imply aérial con-
ditions. Trere

The Crystal Falls Iron- Bearing District of Michigan. By J. Morcan
CLEMENTS and Henry Lioyp Smyru, with a chapter on the
Sturgeon River Tongue by William Shirley Bayley and an
Introduction by Charles Richard Van Hise. U.S. Geolog-
ical Survey. Monograph XXXVI. Washington, 1899.

This report is the third in a series of four monographs on the iron-
bearing district of the Lake Superior Region. Two having been
published previously: one on the Penokee district (Monograph XIX).
The other on the Marquette district (Monograph XXVIII). The
fourth, on the Menominee district, is to follow.

The Crystal Falls district was divided areally, the western half being
studied by Mr. Clements and the eastern half by Mr. Smyth, and the
Sturgeon River Tongue by Mr. Bayley. The investigation was con-
ducted under the charge of Mr. Van Hise, who sums up the general
results in an introductory chapter. ‘The district embraces 840 square
miles. As pointed out in the introduction the rocks belong to the
Archean and Algonkian. The latter consisting of a Lower Huronian
and an Upper Huronian separated by unconformity. The Archean is
believed to be wholly igneous in origin, it occupies a broad area in the
eastern part of the district and has not been closely investigated.
Several smaller areas occur within parts of the region carefully studied.
Owing to the readily decomposable nature of the rocks in places and
to the drift mantle the detail character of the formations is unknown
for part of the area described by Clements, and in the belt worked by
Smyth the rock surface is almost wholly concealed by glacial deposits
and vegetation. It will be seen under what adverse circumstances the
field work was carried forward, and how much credit is due the geol-
ogists who have brought to light so much valuable information from
so unpromising a region.

The Lower Huronian consists of quartzite, dolomite, slate, a volcanic
formation, and some schists. ‘The series has a minimum thickness of
2200, and a possible maximum thickness of 16000 feet. The sediments
probably nowhere exceed 5000 feet in thickness. ‘The Upper Huronian

REVIEWS 383

is a great slate and schist series, not separable into individual forma-
tions, and whose thickness cannot be approximately estimated. All of
these formations have been cut by igneous rocks of various kinds and
at different epochs.

Metamorphism has greatly altered the character of the Algonkian
rocks. In the Lower Huronian the quartzite is the altered form of a
sandstone and: conglomerate in which the pebbles have been nearly
destroyed. It is in places schistose. The dolomite is a nonclastic sedi-
ment. ‘The slate or schist isan altered mudstone. The volcanic forma-
tion is perhaps the most characteristic feature of the Crystal Falls
district. It occupies a larger area than the other Lower Huronian
formations and consists of basic and acid rocks, lavas and tuffs, with
subordinate interbedded sedimentary rocks. The iron-bearing forma-
tion, cailed the Groveland, consists of sideritic rocks, cherts, jaspillites,
iron ores, and other varieties characteristic of the iron-bearing forma-
tions of the Lake Superior region.

After elevation and unequal erosion of the Lower Huronian, con-
ditions of deposition covered these formations with sandstone and
slate conglomerate, passing upwards into shales and grits, subse-
quently altered to mica-slates and mica-schists. These were followed
by combined clastic and non-clastic sediments, the latter including
iron-bearing carbonates. Above these is a great thickness of mica-
slates and mica-schists.

After a long period of deposition a profound physical revolution
occurred, raising the region and folding it in a most complex manner.
The folds have steep pitches indicating great compressive stresses in
all directions tangential to the surface of the earth. Subsequent to or
during the late stage of this time of folding there was a period of great
igneous activity, probably contemporaneous with the Keweenawan,
intruding within the rocks vast bosses and numerous dikes of peridotites,
gabbros, dolerites and granites. These intrusives, while altered by
metasomatic changes, do not show marked evidence of dynamic meta-
morphism.

Subsequently the region was subjected to great denudation and
reduced approximately to its present configuration. In late Cambrian
time Upper Cambrian sediments were deposited upon it. Whatever
may have been deposited upon the Cambrian has been removed by
erosion together with most of the Cambrian. If the region was again
submerged in Cretaceous times no evidence of the fact remains. ,

384 REVIEWS

During the Pleistocene period a thick mantle of glacial deposits was
spread over the entire area, which has been eroded far enough to
uncover the rocks here and there.

Clements’s description of the western part of the district treats of
the surface features, the economic resources and the petrographical
character of the various formations, especial attention being paid to the
volcanic rocks. ‘The great abundance of volcanic breccias and tuffs
indicates the probable existence in Huronian time of a volcanic cone
in this region, but the possible lucation of its vent has not been dis-
covered. A small part of the igneous rocks are acid, their area being
too small to map on the scale of publication. They include rhyolite-
porphyries and aporhyolite-porphyries and breccia of the latter. The
great part of the volcanics are metabasalts and breccias of the same.
An interesting development of ellipsoidal structure is noted. The
pre-Cambrian intrusive rocks include granites and rhyolite-poryhyry,
metadolerite, meta-basalt and picrite-porphvry, besides a series con-
sidered to be closely connected genetically ranging from granite,
tonalite and quartz-mica-diorite through diorite, gabbro, and norite to
peridotite. The diorite is closely related to monzonite.

In the second part of the monograph Smyth discusses at length the
effect of buried magnetic ores on the magnetic dip needle, describes
its use and the results of careful observations in locating the iron-bear-
ing deposits. He also describes the different formations structurally
and petrographically. The same is done by Bayley for the Sturgeon
River Tongue. J: 3P ae

The Geography of Chicago and its Environs. By Roun D.
SALISBURY and WiLLIamM C. ALDEN. Bulletin No. 1 of the
Geographic Society of Chicago, published by the Society.
Chicago, 1899. 64 pp.

This pamphlet is a model essay on local geography written in an
interesting style and illustrated in an attractive and instructive manner.
From the maps and descriptions it is learned that Chicago is situated
on a plain which stretches from Winnetka, sixteen miles north, to
Dyer, about twenty-eight miles south of Chicago, and sweeps eastward
around the southern end of Lake Michigan. This plain is narrower at
its extremities and has a maximum width of fifteen miles in about the
latitude of Chicago; it is imited on the east and northeast by Lake

REVIEWS 385

Michigan, on the west and southwest generally by the Valparaiso
moraine which loops around the southern end of Lake Michigan,
through northern Indiana into Michigan. The plain topography is
varied by three prominent “islands:” Stony Island, a drift-covered,
dome-shaped hill of Niagara limestone with quaquaversal dip; Blue
Island, a single morainic ridge about six miles long and fifty feet above
its surroundings; and Mt. Forest Island, a portion of the Valparaiso
moraine about 120 feet higher than the plain, separated from the rest of
this moraine by the Chicago outlet. The plain is continued through the
Valparaiso moraine southwest of Chicago by the Chicago outlet, which
is divided by Mt. Forest Island into the Sag outlet and the Des Plaines
outlet. The Des Plaines outlet is now followed by the Chicago Drain-
age Canal. Several less conspicuous gravel and sand beach ridges
converging toward the Chicago outlet from the northeast and south-
east help to break the monotony of the plain. On these ridges are
oak groves, which have apparently suggested the names for the towns
Oak Park, Oak Lawn, Englewood and others. The eastern third of
the plain is largely made of gravel and sand. With the exception of
the beach ridges, the western two thirds is largely of till. These deposits
vary in depth from o to 130 feet. The country rock is Niagara lime-
stone which has an elevation varying from 124 feet below the lake level
to about 20 feet above it in Stony Island, and roo to rro feet above it
under the Valparaiso moraine. The southeastern edge of the plain is
occupied by a series of small lakes, the basins of which are in large
part made by enclosing beach ridges. At the south end of Lake
Michigan there are sand dunes with a maximum height of 100 to 200
feet. Other smaller dune areas exist nearer the city.

The main recorded events in the geographical history of the region
since Devonian times are: (1) Withdrawal of the sea and destruction
of formations younger than the Niagara with the exception of some
fossiliferous Devonian material preserved in joints of the Niagara
formation; (2) invasion of the ice in the glacial period, rounding off
the angularities of the rock surface and probably diminishing the relief
of the region by deposits of drift. At a late stage of the ice invasion the
Valparaiso moraine was made. (3) As the ice edge retreated from the
Valparaiso moraine a lake accumulated in the depression between the
ice front and the moraine until the water stood at an elevation sixty feet
above the present Lake Michigan when it overflowed to the west through
the valley of the Des Plaines River and through the Sag outlet. To

386 REVIEWS

this lake Mr. Leverett has given the name Lake Chicago. The stages
in the history of this lake are as follows: f

(az) Glenwood stage, the highest stage, when the level was sixty
feet higher than Lake Michigan is now. During this stage the outlet
was cut down twenty feet.

(4) A stage of recession, when discharge through the Chicago out-
let ceased and the water withdrew from the Chicago plain in part or
entirely. During this stage deposits of peat accumulated.

(c) Calumet stage, in which the water again discharged through the
Chicago outlet at a level forty feet higher than the present level of
Lake Michigan. During this stage the Calumet beach was formed over
the peat deposits of the preceding stage.

(z) The lowering of the outlet gradually reduced the level of the
lake twenty feet when the Tolleston beach was formed. —

(ec) A lower outlet was opened to the north and the lake fell below
the level of the Chicago outlet. This closed the history of Lake
Chicago and inaugurated that of Lake Michigan. Between the
Tolleston beach and the shore of Lake Michigan there is an extensive
series of sand and gravel ridges among which lie the small lakes
mentioned above.

Abundant evidence of fresh water life has been found in the
deposits of the Tolleston stage of the lake, but not in the deposits of
earlier stages. On the surface of the Calumet beach, however,.marine
shells of southern species have been found, which may have been:
introduced artificially.

The bulletin is essentially a popularized version of the work of the
United States Geological Survey and is a tribute to the value of its
investigations. It is to be hoped that this bulletin will stimulate the
publication of similar essays on local geography elsewhere. Interest
ip geography is certainly increased by such publications.

CHARLES EMERSON PEET.

RECENT FUBLICATIONS

—Alabama, Geological Survey of. Report on the Warrior Coal Basin.
With fifty figures in text, seven plates and one map. By Henry
McCalley, Assistant State Geologist.

—AGASSIZ, ALEXANDER. Explorations of the “Albatross”’ in the Pacific.
Reprinted from the American Journal of Science, Vol. IX, January,
February, March, and.May numbers.

—Agriculture, Department of. Yearbook for 1899. Washington, D. C.

—BENNETT, C. W. Coldwater, Mich. The Ice Age and What Caused It.
Published serially in the Michigan Miner, May-June Igoo.

—DarTOoN, NELSON H. Preliminary Report on Artesian Waters of a Por-
tion of the Dakotas. Extract from Seventeenth Annual Report of the
U. S. Geological Survey, 1895-6, Part II, Economic Geology and
Hydrography. Washington, 1896.

—EMERSON, BENJAMIN K. The Tetrahedral Earth and the Zone of the
Intercontinental Seas. Annual Presidential Address. With an Appen-
dix. The Asymmetry of the Northern Hemisphere. Bulletin Geologi-
cal Society of America, Vol. II, pp. 61-106. Pls. 9-14. Rochester,
March 1goo.

—GraABAU, AMADEUS W._ Siluro-Devonic Aspect in Erie County, New
York. Bulletin Geol. Soc. of Amer., Vol. XI, pp. 347-376. Pls. 21-22.
Rochester, May Igoo.

—GULLIVER, F. P. Vienna asa Type City. Reprinted from the Journal of
School Geography, Vol. IV, No. 5, May 1900. Thames River Terraces
in Connecticut. Bull. Geol. Soc. Am., Vol. X, No. 808.

—Hay,O. P. Descriptions of Some Vertebrates of the Carboniferous Age.
Reprinted from Proc. Amer. Philos. Soc., Vol. XX XIX, No. 161.

—HAYFORD, JOHN F. Inspector of Geodetic Work, U.S. Coast and Geodetic
Survey. The Transcontinental Triangulation under the 39th Parallel.
Bull. University of Wisconsin, No. 38, Engineering Series, Vol. II, No. 5,
pp. 173-194. Pls. 1-5. Madison, June Igoo.

—-HAworTH, Erasmus. Relations between the Ozark Uplift and Ore
Deposits. Bull. Geol. Soc. Amer., Vol. XI, pp. 231-240.

—Indiana, Department of Geology and Natural Resources, 24th Annual
Report, 1899. Indianapolis.

387

388 RECENT PUBLICATIONS

—Knicut, WiLtpur C. The Jurassic Rocks of Southeastern Wyoming.
Bull. Geol. Soc. Amer., Vol. XI, pp. 377-388. Pls. 23. Rochester, May
1900.

—Louisiana, Geological Survey of. A Preliminary Report on the Geology
of Louisiana. Geology and Agriculture, Part V. By Gilbert D. Harris,
Geologist in Charge, and A. C. Veatch, Assistant Geologist. Report for
1899. State Experiment Station, Baton Rouge, La.

—PACKARD, ALPHEUS S. View of the Carboniferous Fauna of the Narra-
gansett Basin. Proc. of the Am. Acad. of Arts and Sciences, Vol.
XXXV, No. 20, April Igoo.

—United States Geological Survey :

Nineteenth Annual Report, 1897-8, Part II]. Papers chiefly of a Theo-
retic Nature. Part III, Economic Geology. Part V, Forest Reserves,
Atlas accompanying.

Twentieth Annual Report, 1898-9, Part ‘I, Director’s Report, Triangu-
ation and Spirit Leveling. Part VI, Mineral Resources of the United
States, 1898. Metallic Products and Coke. Part VI continued,
Mineral Resources of the United States, 1898, Non-Metallic Pro-
ducts except Coal and Coke.

Monograph XXXII, Part II, Geology of the Yellowstone National Park.
Descriptive Geology, Petrography, and Paleontology, ~ Hague,
Iddings, Walcott, Stanton, Weed, Girty, Knowlton.

Monograph XXXIII, Geology of the Narragansett Basin. Shaler,
Woodworth, Foerste.

Monograph XXXIV, Glacial Gravels of Maine and other Associated
Pleistocene Deposits. Stone.

Monograph XXXVI, The Crystal Falls Iron-Bearing District of Michi-
gan, with chapter on the Sturgeon River Tongue. Clements, Smyth,
Bayley, Van Hise.

Monograph XXXVII, Fossil Flora of the Lower Coal Measures of
Missouri. White.

Monograph XXXVIII, The Illinois Glacial Lobe. Leverett.

—Yaue, H. The Brachiopod Lyttonia from Rikuzen Province. Reprinted
from the Journal of the Geological Society, Tokyo, Vol. VII, No. 79,
Japan, April 1goo.

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